Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

The objective of this study was to identify the locations of deep-seated gravitational slope deformations (DGSDs) and define the numerical characteristics of these deformations to contribute to the sustainable management of social infrastructure in the event of an increased disaster. The topographic features of the DGSDs were quantitatively characterized based on their surface morphologies. Topographic features indicative of gravitational deformation in pre-slide topographic maps, such as terminal cliff failures, irregular undulations, and gullies, suggest that progressive deformation occurred over a prolonged period. To track the gravitational deformation over time, we interpreted aerial photographs of DGSDs from 1948 and 2012 associated with deep-seated landslides on the Kii Peninsula induced by Typhoon Talas on 2-5 August 2011. Corresponding numerical analysis of the gravitational deformations using 1 m digital elevation models reveals that landslide areas exhibit eight characteristic influencing factors, demonstrating that characteristic morphologies exist in areas that eventually experience landslides. One such morphological feature is the existence of a gently sloping area in the upper section of the deep-seated landslide mass, which comprises a catchment basin without a corresponding valley or gully. These findings suggest that rainwater penetrates the ground, and degrades and deforms the rock within the landslide mass, causing the slope to fail after torrential rainfall. This study holds great significance for advancing sustainable infrastructure development and management and mitigating environmental changes.

DOI： 10.3390/su16135328

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DOI： 10.11532/jsceiii.5.1_230

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

Wavelet analysis is a method for producing microtopographic maps from aerial laser scanning data. In this study, we investigated the setting of the scale factor (s) and a visualization method for the wavelet coefficients to extract geological features (exposed rocks, boulders, and small cliffs) that may function as a source of falling rocks. Grid data with a grid size of 0.5 m were used for the study, which were generated from aerial laser survey data and the results of the survey. A correlation between the specific height difference in the range of 1.0–3.0 m and the positive wavelet coefficient was determined. Consequently, based on these results and those of a study on simulated terrain, a visualization method for the wavelet coefficients was proposed. Herein, setting s = 1.0 and 0.5, it was shown that s = 0.5 was appropriate for identifying geological features that may be considered as sources of rockfall.

DOI： 10.3208/jgs.19.69

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejj.23-00046

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejj.23-16161

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG SINGAPORE PTE LTD  

The objective of this study was to identify the locations of deep-seated gravitational slope deformations (DGSDs), which are precursors of future deep-seated landslides, and to characterize the numerical characteristics of these deformations in order to theoretically elucidate observed phenomena. To this end, we attempted to characterize quantitatively the topographic features of DGSDs, focusing on surface morphology. Signs of gravitational deformation that are frequently observed in pre-slide topographic maps include terminal cliff failures, irregular undulations, and gullies. The presence of these topographic features suggest that progressive deformation has occurred over a prolonged period of time. In order to track gravitational deformation over time, in this study, we interpreted aerial photographs of DGSDs that were associated with deep-seated landslides (DLs) on the Kii Peninsula that had been induced by Typhoon Talas, which occurred from 2 to 5 August 2011. We were able to observe the deformations that are considered to be caused by gravitational deformation over time. Numerical analysis using 1-m digital elevation models (DEM) revealed that the landslide areas exhibited characteristic eigenvalue ratios, slope angles, topographic wetness indices, and underground openness, demonstrating that characteristic morphologies exist in the areas that eventually experience landslides. One such morphological feature is the existence of a gentle sloping area in the upper section of the mass comprising a catchment basin, but without the corresponding valley and gully. The findings suggest that rainwater penetrates into the ground, degrading and deforming the rock within the landslide mass, and ultimately causes the slope to fail after torrential rainfall.

DOI： 10.1007/978-981-99-9061-0_20

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.rineng.2023.101415

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DOI： 10.11532/jsceiiai.4.2_35

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Publishing type：Research paper (scientific journal)   Publisher：International Journal of Geomate  

DOI： 10.21660/2023.110.3941

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Publishing type：Research paper (scientific journal)  

There has been an increasing demand for detailed and accurate landslide maps and inventories in disaster-prone areas of subtropical and temperate zones, particularly in Asia as they can mitigate the impacts of landslides on social infrastructure and economic losses. Hence, in this study, models using automatically constructed high-performing convolutional neural network (CNN) architectures for landslide detection were applied and their outcomes were compared for landslide susceptibility mapping at the Kii peninsula, Japan. First, a total of 38 landslide and 63 non-landslide points were identified and divided into 70% and 30% of training and validation datasets, respectively. Eight landslide influence factors were used: slope angle, eigenvalue ratio, curvature, underground openness, overground openness, topographic witness index, wavelet, and elevation. These factors were selected using a 1-m DEM, which is easy to acquire and process data. Experimental results of model evaluation using receiver operating characteristics (ROC), area under the curve (AUC), and accuracy showed that the optimal models (ROC = 96.0%, accuracy = 88.7%) were more accurate than initial models (ROC = 91.1%, accuracy = 80.7%) in predicting landslides spatially. Furthermore, the landslide susceptibility mapping is consistent with the trends in the distribution of gentle slopes and knick lines unique to the study area and can be used as a powerful method for predicting landslides in future.

DOI： 10.1007/s11069-023-05862-w

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Publisher：CRC Press  

DOI： 10.1201/9781003359159

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Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/00221686.2022.2106596

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

To rationally design rockfall countermeasures, detailed rockfall behavior must be predicted using numerical simulations based on the conditions of slopes and rockfalls. In this study, we perform a rockfall simulation using discontinuous deformation analysis. This method is used to analyze the motion between blocks composed of polygons of arbitrary elastic bodies; furthermore, the energy conservation law and the uniqueness/convergence of the solution are guaranteed for the entire analysis target. Additionally, the rockfall shape is reproduced in detail. Both the rockfall shape and a parameter known as the velocity energy ratio, which indicates the decay of energy at the collision time of the rockfall, significantly affect the rockfall behavior. In this study, we model the actual slope shape from data measured via airborne laser and quantitatively evaluate the effect via simulations by changing the rockfall shape and velocity energy ratio. In this paper, we consider how to use the simulation for the design of rockfall countermeasures based on the results such as the change in the amount of jumping due to the difference in slope shape, geology, and rockfall shape.

DOI： 10.1088/1755-1315/1124/1/012092

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Other Link： https://iopscience.iop.org/article/10.1088/1755-1315/1124/1/012092/pdf

Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejj.22-22014

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Microtopographic and topographic maps produced from aerial laser survey data are increasingly used for commercial purposes. Unlike slope gradient maps, wavelet analysis maps can extract terrain steps without being affected by slope inclinations. First of all, we created a simulated terrain with varying slopes and specific height differences to examine those height differences that can be represented by wavelet analysis and slope gradient maps. Then we examined the height differences that can be extracted from the wavelet analysis and slope gradient maps for an average slope of approximately 40°, including the rockfall source, using the results of the field survey. The height difference that could be extracted from the wavelet analysis maps was approximately 2 m, whereas the difference that could be extracted from the slope gradient maps was 4 m or more. Therefore, wavelet analysis maps are better in extracting small height differences compared to slope gradient maps.

DOI： 10.2208/jscejj.22-22052

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejhe.78.2_i_133

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Publishing type：Research paper (scientific journal)  

Recent advancements in remotely sensed techniques have markedly expanded data acquisition potential in riverine studies, but the techniques' applicability must be validated and improved because of uncertainties associated with diverse field conditions. This study is the first experimental evidence of using a newly designed unmanned aerial vehicle (UAV)-borne green lidar system (GLS) and deep learning-automated space–time image velocimetry (STIV) for remote investigation of hydraulic and vegetation quantities of the gravel-bed Asahi River in Okayama Prefecture, Japan. In addition to identifying bed deformation in waters shallower than 2 m, the GLS point clouds characterized the submerged infrastructure with block detailing patterns, thereby identifying positional displacement and severely damaged parts. This paper also presents a noncontact method of estimating incremental river discharge. Compared to benchmarked flow model estimates, remotely sensed discharges for three transects covering shallower, deeper, and partially submerged woody vegetation areas were overestimated by 1–11%, with 4% underestimation for another cross-section. The STIV analysis also showed complicated flow patterns that were reasonably confirmed by flow vectors from depth-averaged modeling. Ultimately, depth-averaged flow model estimates validated hydraulic parameters derived remotely from GLS and STIV, and vice versa. In addition to approximating vegetation growth rates, the study using GLS attributes accurately identified riparian vegetation types as herbaceous (70%), woody (86%), and bamboo groves (65%). Finally, our findings provide insight into the management of shallow clear-flowing vegetated rivers and remote sensing of streamflow to validate hydrodynamic-numerical methods.

DOI： 10.1002/rra.4042

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Publishing type：Research paper (scientific journal)   Publisher：The Japanese Geotechnical Society  

DOI： 10.3208/jgs.17.135

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

This study presents an identification method for rockfall sources, using remote sensing and machine learning technology, to reduce overlooking during the inspection cycle and improve slope management efficiency. In road disaster prevention inspections, rockfall damage from overlooked points has been reported, and improvements are essential to ensure that road disaster prevention inspections are carried out. In such cases, the use of remote sensing technology is an effective measure. In particular, effective inspection can be expected by utilizing the terrain analysis map created from the measurement data. In this research, we propose a system that applies machine learning to object detection to a terrain analysis map and detects the source of rockfall on the desk. Based on the wavelet analysis map, which is a type of terrain map, object detection by a support vector machine was applied. As a result, the proposed method succeeded in detecting all existing inspection points. We showed its effectiveness as a tool for improving the efficiency of road disaster prevention inspections.

DOI： 10.3208/jgs.17.147

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Publishing type：Research paper (scientific journal)  

Investigations using maps that reflect slope conditions have been conducted for slope inspection. However, oversight at the time of inspection has become a problem owing to unsatisfactory map performance. This paper presents a microtopography highlight map created using a high-density aerial laser survey as a new inspection tool and evaluates the influence of survey conditions on a desk study of rockfall sources using the map to develop an efficient slope inspection method. The microtomography highlight map is created by the combination of a slope map, which displays the slope angles, and a wavelet analysis map, which displays the unevenness of the slope. The slope and wavelet analysis maps are created via terrain analysis based on the digital elevation model, which is created using aerial laser survey results. In this study, we demonstrated slope inspection using a map of grid size 50 cm on two slopes where there was a risk of falling rocks. A comparison of the desk study and field research showed that using the map was effective in extracting the source of the rockfall (>2 m height). In addition, the verification results showed that the measurement conditions affect the representation of the map, and that the measurement should be conducted in winter to produce a more detailed map, which leads to effective inspection.

DOI： 10.21660/2022.94.j2392

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Publishing type：Research paper (scientific journal)   Publisher：IWA Publishing  

<title>Abstract</title>
In response to challenges in land cover classification (LCC), many researchers have experimented recently with classification methods based on artificial intelligence techniques. For LCC mapping of the vegetated Asahi River in Japan, the current study uses deep learning (DL)-based DeepLabV3+ module for image segmentation of aerial photographs. We modified the existing model by concatenating data on its resultant output port to access the airborne laser bathymetry (ALB) dataset, including voxel-based laser points and vegetation height (i.e. digital surface model data minus digital terrain model data). Findings revealed that the modified approach improved the accuracy of LCC greatly compared to our earlier unsupervised ALB-based method, with 25 and 35% improvement, respectively, in overall accuracy and the macro F1-score for November 2017 dataset (no–leaf condition). Finally, by estimating flow-resistance parameters in flood modelling using LCC mapping-derived data, we conclude that the upgraded DL methodology produces better fit between numerically analyzed and observed peak water levels.

DOI： 10.2166/hydro.2022.134

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/rra.3875

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/rra.3875

Language：English   Publisher：Japan Society of Civil Engineers  

This study uses an unmanned aircraft mounted green Light Detection and Ranging (LiDAR) system to verify the learnability associated with deep learning regarding land cover classification (i.e., evaluated by the average and the absolute difference value of label-based F1, overall accuracy or Macro F1 under the premise of cross-seasonal mutual-prediction). Image fusion method in this study mainly attempts to superimpose the visualized LiDAR data with the aerial photographs to provide new features. LiDAR data are visualized using high contrast color scale (default), average high contrast color scale (same color, different split points as default), and high contrast gray color scale (different color, same split points as default). The reason of setting these methods is to compare the impact of split points and point-associated color in the color scale on learnability of cross-seasonal data. It is worth noting, however from the view of the results, that relying solely on aerial photographs is not sufficient, comparing with image fusion method, especially when training and predicting using cross-seasonal data. From the comparison of the label-based F1, this study has proved the necessary impact of LiDAR on vegetation label-based land cover classification.

DOI： 10.11532/jsceiii.3.3_15

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejhe.78.2_i_1153

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Publishing type：Research paper (international conference proceedings)   Publisher：International Association for Hydro-Environment Engineering and Research (IAHR)  

DOI： 10.3850/iahr-39wc252171192022989

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

This paper describes application of airborne LiDAR bathymetry (ALB) with near-infrared and green pulsed lasers for gathering distributed vegetation conditions and topo-bathymetric data for rivers. For the lower Asahi River of Okayama Prefecture in Japan, the ALB data validity was verified using field observation data. This study also examined the applicability of ALB data for numerical simulations of the lower Asahi River flooding in early July 2018 in Japan, comparing simulated and observed data. Results demonstrated that the methodology for this study works well for parameterization of distributed vegetation on a reach scale. This study also applied numerical tests to investigate the effects of vegetation establishment on flood control plans for the lower Asahi River using parameters validated for flood flow simulations. Results demonstrate that the predicted water level markedly exceeds the high water level because of thick vegetation presently established along few-kilometerlong upstream sections of the targeted river reach. Therefore, we conclude that the present findings can support cost-effective management tasks for vegetated rivers.

DOI： 10.1016/j.jher.2021.06.005

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1755-1315/861/4/042048

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Other Link： https://iopscience.iop.org/article/10.1088/1755-1315/861/4/042048/pdf

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

<p> During the construction work of mountain tunnels, monitoring the tunnel face is required all the time to prevent labor accidents. Small rock falls can be a sign of a large scale collapse, despite the time lag between them. However, it is difficult for the supervisor to detect small rock falls by visual monitoring. Therefore, in this research, a monitoring system was developed for detecting falling objects based on the background substraction. In order to monitor small rock falls, we limited the analysis scope of detecting falling objects process to the tunnel face which was detected by semantic segmentation and removed minute objects such as tunnel dust and video noise. Next, we conducted an image analysis by the developed system using footages which simulate falling rocks, the sign of a large scale collapse. The result showed that small rock falls could be detected, which implies the mitigation of labor accidents.</p>

DOI： 10.2208/jscejcei.77.2_I_77

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.11532/river.27.0_51

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

<p> Flooding with a discharge of approximately 4200 m³/s occurred in the lower Asahi River during the Heavy Rain Event of July 2018. The flood flow over the historic diversion weir was the first time ever observed after its renewal work. For flood control tasks, hydraulic engineers have examined the diversion discharge by laboratorial experiments and two-dimensional (2-D) numerical simulations. However, the flood impacts on the subsequent changes of both vegetation and riverbed conditions have not been fully investigated yet in the earlier works. Furthermore, the 2-D flow model commonly cannot allow for reproducibility of flows around the actual river section with a complicated bed geometry and heavily vegetated conditions. Therefore, a new 3-D numerical model has been proposed herein for flood flow simulation based on a porous model considering distributed vegetation establishment using airborne laser bathymetry (ALB) data before and after the rainfall event. Simulated results demonstrated that the proposed model performed well, compared with the existing 2-D model and field observations.</p>

DOI： 10.2208/jscejhe.76.2_I_985

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Language：Japanese  

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Language：Japanese   Publisher：Japan Society of Geoinformatics  

<p>This study investigates the three-dimensional point cloud density necessary to quantify topography for prediction purposes. Index parameters have been collected for main scarps, flanks, scarplets, open cracks, and gravitational deformations, all of which are elements relevant to topographic interpretation. However, no comparison has been made between point density and qualitative terrain interpretation using aeronautical laser measurement methods and equipment. The study compares the point cloud acquisition efficiency of two different laser scanning systems, ALS and UAV, using seven different point cloud densities. In this paper, we examine the equipment, measurement accuracy, and topographically interpretable fine topography by applying the scanning systems at a rock fall site where measurements were taken 4 times. We found that a small cliff, 0.3 m tall, on a gentle slope can be detected at a point density of 1.0 point/m², and that detection of a 0.45 meter tall cliff on a steep slope is possible with a point density of 59 points/m².</p>

DOI： 10.6010/geoinformatics.31.2_37

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejhe.76.2_i_529

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Language：Japanese  

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Language：Japanese   Publisher：Japan Society of Geoinformatics  

<p>In recent years, due to climate change, heavy rainfall has occurred frequently, and the damage caused by inundation has increased. However, the soundness of the levee is done by the visual inspection while experts walk. Therefore, it is evaluated depending on the skills and experience of the experts. There has been a need for a method that can monitor the outer shape of the levee in detail in normal times and after flooding, and to conduct quantitative evaluation for taking measures immediately if abnormalities such as deformation are found. Mobile Mapping System (MMS), which is equipped with a laser scanner on a vehicle, has attracted attention as a method that can quickly carry out high-precision surveying. When the survey is conducted by using MMS that travels on the levee crown, a dead angle of laser irradiation occurs. It is possible to detect the subsidence of the levee crown with high accuracy, but it is not possible to detect where it is necessary to take measures in the whole levee including the slope surface by using MMS survey. In this paper, we clarified what kind of problem the dead angle of the laser light leads to, and discussed the advantages of acquiring 3D data for grasping the topography of the levee by irradiating the laser from a high position. We showed the relation between the laser irradiation angle and the traveling speed of the vehicle and the surveying accuracy, and considered the position to install the laser scanner device to acquire the 3D data up to the slope toe area. We also verified the effectiveness of the laser surveying which irradiates from the 5.5m height. In comparison with the conventional laser surveying by vehicle travel, it was demonstrated that the method we considered was efficient as a surveying work and detected a detailed deformation on the slope surface because it provided high density laser point clouds. Since the heavy rainfall of short duration will increase in the future, it is expected that the results of this study are considered to be useful as a method for efficiently grasping the topographical features of the levee.</p>

DOI： 10.6010/geoinformatics.30.3_101

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Language：Japanese   Publisher：The Japan Landslide Society  

<p>  The 2011 Typhoon Talus caused slope damage in the Kii Peninsula. This study reviews the landslide indicators and determines the microtopography of 38 areas affected by landslides caused by the typhoon along with 63 unaffected areas. Results indicate that the areas associated with collapse have gravitationaldeformation, exhibiting end collapses with high probabilities. These topographic combinations are characterized by gravitational creep, such as the appearance of the main scarp on the earth's surface in areas characterized by surface ruptures. In the landslide development stage, these microtopographies relate to a transitional stage recognized as a change in gravity prior to initial fluctuation and can be classified into two periods depending on their frequency. Although these factors are limited to specific meteorological conditions, topography, and geological structures, they can be used to effectively forecast slope damage in areas with existing high-precision DEM data.</p>

DOI： 10.3313/jls.56.141

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J-GLOBAL

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Language：Japanese   Publisher：The Japan Landslide Society  

&lt;p&gt;  In slope disasters which increase recently, falling rocks from steep slopes occur even checked-location by preliminary survey. It is important to confirm the existence of falling rock and its origin corresponding to the preliminary survey in the steep slope maintenance, but it has problems of visibility as vegetation and steep slope safety. The efficiently preliminary survey has important to take acquire detailed topographical data. Airborne Laser Scanning and Terrestrial Laser Scanning with remarkable improvement in performance has been widely known as a surveying technique for acquiring topographic data with a high accuracy. &lt;/p&gt;&lt;p&gt;  In this study, Three-dimension point cloud by aircraft and terrestrial laser Scanning were used in combination with objects on steep slopes facing river. Scanning were made at multiple times. We have evaluated the landslide variation amount with a high accuracy by discriminating characteristic land features from digital elevation model, which is Substratum Digital Elevation Model （S-DEM）and ICP analysis. We also describe the result that it is possible to predict the movement of steep slope occurred in the area. These methods are effective of the preliminary survey for steep slope maintenance.&lt;/p&gt;

DOI： 10.3313/jls.55.65

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Developing technologies of Airborne Laser Bathymetry (ALB) have recently enabled us to obtain topographical data on river channels including underwater area. The reproducibility of river channel topography is estimated to effect on numerical analysis for river. However, there are few studies using ALB data, so the effect of it on analysis results has not been considered in particular.<br>In this study, the topography data obtained by ALB measurement is examined the accuracy. Furthermore, we studied the effect of the topography data on analysis by comparing results of river-bed variation analysis and the difference data of ALB measurement.<br>The topography data obtained ALB measurement showed the same topographical shape as cross-sectional survey result. In addition, by comparing analysis results and the difference data of ALB measurement, analysis using ALB data showed a trend similar to measured value than using conventional data.

DOI： 10.2208/jscejam.74.I_465

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;This article examined efficient method for falling rock investigation using tablet type GIS and microtopography highlight map. In the experiment field, it was possible to extract a steep cliff with a height difference of about 1.5m or more and an inclination angle of 60&deg; or more from microtopography highlight map, but it was also confirmed the necessity of field investigation including risk judgment. In the field investigation, we verified the relationship between the microtopography highlight map and the self position indicated by the tablet terminal at the slope of the mountain, and it was effective for approaches to falling rock source. Moreover accumulation of investigation data using tablet type GIS not only contributes to the efficiency improvement of disaster prevention record update but also it is effective for future maintenance because it also has position repeatability of falling rock source.

DOI： 10.2208/jscejcei.74.I_121

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&nbsp;While slope failures due to torrential rain occurs frequently in all over the country, it is used two-dimensional saturated-unsaturated flow analysis by finite element method and limit equilibrium method in many of the design practices and various research. In addition, osmosis water pressure of the unsaturated zone obtained by flow analysis is not considered to slope stability evaluation. Therefore, in this study, the coupling was carried out analysis of the seepage and stress by the shear strength reduction method using a simple model of masa soil. In addition, osmotic pressure and torrential rains of the unsaturated zone was carried out the impact study on the stability of the slope. And it was further applicability verification of the design practices of the limit equilibrium method by comparison with the sliding safety factor by comparison with the conventional method. It showed that conventional method is not applicable cases.

DOI： 10.2208/jscejhe.74.I_13

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Language：Japanese   Publisher：土木学会  

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J-GLOBAL

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Language：Japanese   Publisher：日本測量協会  

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J-GLOBAL

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&nbsp;In recent years, falling rock accidents have occurred frequently, and the momentum to tackle the rock fall prevention measures is increasing. However, in lots of the falling rock prevention measures, low resolution drawings are used. Therefore, the investigating falling rocks in the field and the accuracy of the position of the falling rock generation source are poor. There is a problem of missing a place where there is a danger of falling rocks.<br>&nbsp;In this paper, we utilize high density laser point cloud data using aircraft and create a map that emphasizes micro topography. This map is a transparent composition of the inclination amount map, the wavelet analysis diagram and the contour map together. We propose a method for extracting the falling rock origin with a high accuracy by using it. As a result of verifying the laser point cloud data in summer and winter, we could extract the falling rock generation source &ldquo;cliff&rdquo; by using measurement data of the longitudinal direction of the road in winter. This clarified that the proposed method is useful.

DOI： 10.2208/jscejcei.73.I_92

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DOI： 10.2208/jscejcei.73.I_53

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&nbsp;This paper describes the applicability assessment of height measurement of river bank crown by Mobile Mapping System (MMS). The aim of this study is to establish MMS measurement method and extract height of river bank crown methodology from MMS point cloud. Our proposed methodology is the approach based on flatness and continuousness form of river bank crown. In order to examine our methodology, we had been carried out an actual MMS observation and MMS point cloud generation. Through our practical experiments and an actual evaluation, we confirmed that our proposed methodology can evaluate less than 10cm accuracy and continuousness height of river bank crown. It was also concluded that the MMS is the most appropriate method in terms of the efficient and effective river bank height management.

DOI： 10.2208/jscejcei.73.I_53

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&nbsp;In the construction work of the mountain tunnel, it is a problem that workers are injured due to disaster caused by fall of rock. In ordet to prevent labour accidents , it is important to monitor deformation of tunnel face during work constantly. However, it has been difficult to detect the deformation by visual monitoring of the supervisor. Therefore, we have been developing tunnel face deformation monitoring system using background subtraction which is a method of image processing to detect moving objects. In this study, in order to make it possible to monitor the deformation by image analysis, we examined the applicability to the site from analysis results of videos moving rock and that excavating tunnel face. As a result, it was found that it is expected to detect the deformation that is difficult by visual monitoring, and to detect only the deformation by removing moving objects other than deformation. Finally, we indicated possibility that the risk of accidents is reduced.

DOI： 10.2208/jscejcei.73.I_226

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&amp;nbsp;Because road tunnel inspection manual was revised in June, 2014, the periodic inspection once in five years was required. There are many road tunnels of 11,000 in Japan, development of inspection technology, and securing of talented person becomes important. As an inspection robot technology, MIMM (Mobile Imaging Technology System &amp; Mobile Mapping System) attracts attention now. In this research, we weighed MIMM measurement result against a proximity viewing result in a real tunnel and carried out the quality inspection of the crack.

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&amp;nbsp;The lack of resources and the talented person concerned with maintenance becomes the serious problem. Active introduction of ICRT is expected as one of the solutions. In late years it is in condition to be able to utilize a profit by measurement data because MMS (Mobile Mapping System) is utilized in various scenes. We think that it becomes the most effective data use to utilize data of MMS versatilely. Therefore, it is necessary to acquire data in a general viewpoint of the road management. We calculated IRI from the road surface profile that I made by data of standard MMS and inspected the usefulness of acquisition data. As a result, we demonstrated that IRI calculation was possible by the road surface profile that we made from laser and POS/LV of standard MMS.

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&amp;nbsp;In the &quot;Periodic inspection rocedures&quot; of various road structures formulated in June, 2014, it is mandatory to make the regular inspection for existing road structures once every five years. For this reason, technological development for an efficient maintenance management was pointed out as an urgent task. &amp;ldquo;Mobile Imaging System&amp;rdquo;, which was developed few year ago, measures road structures by using digital video camera and laser scanner mounted on a specialized vehicle. In addition, the measuring precision is high. However, in many cases the operation cost is expensive. Therefore, it is difficult for local government with budget limitation to apply it to the regular inspection. Authors has developed a reasonable &amp;ldquo;Mobile Imaging System&amp;rdquo;, that is an mountd on a maintenace patrol car, measurement accuracy same as a specialized vehicle, decomposable and has developed an image stiching program for panoramic images.

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&nbsp;The objective of the study is to measure the displacement of the crack by using a digital camera image. In this measurement technique proposed here, the reflective targets are installed at the measurement point around the crack as gauges and the digital image of reflective targets is subjected to process which consists of image processing and photogrammetry, and the two dimensional displacement of the crack is calculated based on the coordinates of reflective targets. In this paper, experiments were performed to verify the accuracy and precision of the measurement. This paper also showed the actual tunnel measurement results to demonstrate that the cracks on the tunnel wall by using this method.

DOI： 10.2208/jscejte.72.I_87

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&nbsp;To effectively mitigate the rockfalls from the slopes neighboring railway lines, the risk of individual rock should be quantified with consideration of its stability and damage cost, and then the risk-based counter action should be done. However, assessing all the rocks in all the slopes along with the lines is quite difficult due to the restriction of budget and human resources. Therefore, in this study, two-step risk assessment was proposed: first, the target lines to be assessed were preliminarily selected according to the expected number of rockfalls which can be calculated by previous data. Then the risk of individual rockfall in the target lines was calculated by multiplying the damage cost and the collision probability between the rock and train. Finally, optimum counter action was determined according to the risk reducing effect or its benefit by cost.

DOI： 10.2208/jscejcm.72.31

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&nbsp;This paper presents a study on monitoring method of crack width on concrete structures using digital photogrammetry. In this measurement procedure, the reflective targets are installed at measurement points around the crack as the gauges, and the deformation of crack width is calculated from one image taken from arbitrary camera positions. In this paper, we verify the relation between the accuracy/precision and the distance/angle of photographic positions from the targets in experiments, and the results showed that it was possible to measure the displacement of crack about 0.1mm at 100m and 30 degree photographic angle. Moreover, application of this method to measuring crack changes on actual concrete structures showed that it was possible to monitoring of the structures easily by using this method.

DOI： 10.2208/jscejcei.72.I_103

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Inspections to evaluate the safety, durability, and service life of aging infrastructure play an important role in determining the countermeasures that need to be taken, such as reinforcement, repair, and reconstruction. In infrastructure containing concrete, such as bridges and tunnels, crack widths and patterns on surfaces are two of the most important signs used to estimate durability. Current conventional techniques used for this purpose suffer from challenges such as tediousness, subjectivity, and high cost. Consequently, a new measurement technique that overcomes these challenges while measuring crack displacement with high accuracy and precision in aging civil engineering structures is needed. In this paper, we proposed a technique for measuring crack displacement using a digital camera image. In the proposed technique, reflective targets are established around both sides of a crack as gauges, and subsequent digital camera images of the targets are subjected to image processing to determine the displacements of the targets. These displacements can be measured using images captured from any arbitrary camera position. The results of experiments conducted to verify the efficacy of the proposed method show that crack displacements of less than 0.10 mm can be measured with high accuracy and precision using digital images captured at a distance of 10.0 m from the target, while less than 0.20 mm changes in the tensile displacement of the crack can be measured from an image captured at 25.0 m from the crack. Measurement results obtained from a tunnel are also presented to show that cracks in the walls of an actual tunnel can be identified through simple measurements. These measurements, taken over a period of one year, indicate that the tendency of crack displacement and slide movements are in close agreement.

DOI： 10.1016/j.aei.2015.05.005

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DOI： 10.4287/jsprs.54.166

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&nbsp;A catastrophic accident involving road users occurred at Sasago tunnel built in Yamanashi prefecture in December 2012. In Japan, many infrastructures have been constructed have contributed to economic growth, but recently one of the most challenging issues is to know whether these old infrastructures are safe or not, and the inspection to evaluate their soundness will play an important role. Considering these situations, this study proposes a new mobile inspection method using a vehicle with laser scanners and image photographing units as a robot technique introduced to the inspection work. In this paper, the authors discuss the latest management criteria and problems about maintenance for road tunnel, and consider the feasibility of our proposed inspection method. We present the importance of maintenance work by utilizing the robot technique to make maintenance work more efficient, more accurate and safer.

DOI： 10.2208/jscejusr.71.20

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DOI： 10.1016/j.aei.2015.05.005

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Recently it has become important to develop a new monitoring system for structures. This is because the ageing infrastructure and an increase in abnormal weathers caused by the climate change have resulted in hazard assessments becoming more difficult. Therefore, there is a need to be able to monitor vulnerable structures more carefully and to assess their safety in real time. For this purpose, we require a new monitoring system that can monitor a structure more closely, easily, and efficiently than the existing methods. We developed a new monitoringsystem using a Micro Electro Mechanical System and wireless communication. We applied this system to a retaining wall with a deep-seated slope failure, in order to assess the serviceability of this method in general, and the safety of this retaining wall in particular.

DOI： 10.1109/ICSENS.2014.6985285

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With regard to crystalline rock that constitutes deep geology, attempts have been made to explore its hydraulic characteristics by focusing on the network of numerous fractures within. As the hydraulic characteristics of a rock are the accumulation of hydraulic characteristics of each fracture, it is necessary to develop the hydraulic model of a single fracture to predict the large-scale hydraulic behavior. To this end, a simultaneous permeability and shear test device is developed, and shear-flow coupling tests are conducted on specimens having fractures with varied levels of surface roughness in the constant normal stiffness conditions. The results show that the permeability characteristics in the relation between shear displacement and transmissivity change greatly at the point where the stress path reaches the Mohr-Coulomb failure curve. It is also found that there exists a range in which transmissivity is not proportional to the cube of mechanical aperture width, which seems to be because of the occurrence of channeling phenomenon at small mechanical aperture widths. This channeling flow disappears with increasing shear and is transformed into a uniform flow. We develop a simulation technique to evaluate the macroscopic permeability characteristics by the lattice gas cellular automaton method, considering the microstructure of fracture, namely the fracture surface roughness. With this technique, it is shown that the formation of the Hagen-Poiseuille flow is affected by the fracture microstructure under shear, which as a result determines the relationship between the mechanical aperture width and transmissivity.

DOI： 10.1186/1880-5981-66-108

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This paper deals with the development of a three-dimensional slope behavior monitoring method using digital photogrammetry with only simple measurement work. We report its feasibility based on the results of experimental application of the proposed system to actual slope monitoring. In the paper, an appropriate measurement system for slope behavior monitoring was established by applying the following two techniques to the existing photogrammetric technique : one technique for simply obtaining the two-dimensional distribution of displacements with accuracy of 5mm without having to set fiducial points on the slope; and the other technique for obtaining the three-dimensional distribution of coordinate values of measurement points from the geometric constraint conditions of the geodetic network. This paper presents the theoretical development of this new measurement system and actual extensive slope measurement results. The theoretical development shows that slope behavior can be identified through simple measurements. The measurement results demonstrate that the measurements conducted by the proposed system are consistent with the measurement results using conventional extensometers and survey instruments.

DOI： 10.5110/jjseg.54.264

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DOI： 10.5026/jgeography.122.170

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This paper presents some results of studies on application of a monitoring system using Micro Electro Mechanical System (MEMS) sensors in order to measure deformations of a retaining wall. The MEMS sensors have three advantages which are compact, lightweight, and inexpensive. In this paper, the authors propose that using the supports system, the precision of the sensor network system gets higher than before. Using wireless communication between the transmitter and receiver in this system, the data observed by the MEMS sensor is transmitted to the base station directly, and the distance is approximately 500m with good visibility and about 300m with vegetation. The authors applied this system to monitoring an actual retaining wall under construction. It is concluded from the result that the MEMS sensor could measure very small deformations of the retaining wall and the small change of an inclination had been affected by a series of external factors such as rainfalls and an earth pressure from the back of the wall. © SGEM2013 All Rights Reserved by the International Multidisciplinary Scientific GeoConference SGEM.

DOI： 10.5593/SGEM2013/BA1.V2/S02.058

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DOI： 10.1007/s10346-012-0321-0

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Japan is located in Circum-Pacific earthquake zone, which is one of the most seismologically active areas in the world. As a result, landslides have occurred frequently and often cause serious damage not only to human lives but also to the various important structures such as national roads, railway, electric power plans etc. From the engineering point of view, to investigate the mechanism of landslide due to earthquakes and estimate the damage caused by landslides are important issues. In this study, as the first step, to check the validity of DDA simulation for the seismic problems, a series of shaking table tests were carried out in the laboratory and simulated by DDA. Then, one of the largest landslides occurred in Aratozawa Area, Miyagi, Japan in 2008 caused by Iwate-Miyagi Nairiku Earthquake was simulated using DDA and discussed the mechanisms of the landslide. The 2-D DDA model for one of the survey lines was created based on the geological survey, and physical properties were determined from the laboratory tests using rock/soil samples obtained from the landslide site. In this study, to discuss the mechanism of the landslide, a series of parametric study in terms of shear resistance along the fractures was conducted. © 2012 Copyright Taylor and Francis Group, LLC.

DOI： 10.1080/17486025.2011.578672

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

&amp;nbsp;The rainfall storage and infiltration facility of permeable pavement have been attracted attention as a control measure of flood and an environmental improvement measure in urban areas. However, rainfall infiltration of permeable pavement is unsteady flow and strongly dependent on the behavior of unsaturated zones in the pavement. Moreover, the wet condition of subbase course also has a great influence on the rainfall infiltration of the pavement. That&#039;s why previous studies have not made clear the precise the facility of permeable pavement as a flood control. In this paper, experimental studies and simulated analyses were performed to measure the overflow from the pavement under various conditions of rainfall intensities and estimate the rainfall infiltration of the pavement using the measurement data and unsaturated infiltration characteristics of porous asphalt materials. It is clear that this study shows the methods to have a quantitative estimation of the rainfall storage and infiltration facility of permeable pavement.

DOI： 10.2208/jscejpe.68.32

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Survey methods using elastic wave velocity have been performed in order to estimate the pore fluid properties in rock mass, but the viscosity and density of pore fluid have not been estimated quantitatively by the values of velocity or the velocity changes. We describe in this paper whether pore fluid properties can be estimated by using the dispersion of longitudinal elastic waves. We measured the frequency-dependent velocity data of longitudinal elastic waves in porous specimens and the dependence of the velocity dispersion on the kinematic viscosity of pore fluid. Moreover, we try to explain the velocity dispersion shown by the measurement data using the Biot theory. The Biot theory explains that the dispersion phenomenon is caused by the elastic property change in the media with the interaction between the solid phase and liquid phase, so the dispersion is dependent on the properties of liquid phase. The measurement data showed the phase velocities of longitudinal waves increased with an increase of frequencies and the characteristic frequencies which indicate the points of inflection moved to higher frequencies with an increase of kinematic viscosities of pore fluid. We report that we can estimate the kinematic viscosity of pore fluid in rock mass by using the dispersion curves which graphed the relation between the phase velocities and frequencies. © 2012 The Society of Materials Science, Japan.

DOI： 10.2472/jsms.61.222

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Language：Japanese   Publisher：The Society of Materials Science, Japan  

Survey methods using elastic wave velocity have been performed in order to estimate the pore fluid properties in rock mass, but the viscosity and density of pore fluid have not been estimated quantitatively by the values of velocity or the velocity changes. We describe in this paper whether pore fluid properties can be estimated by using the dispersion of longitudinal elastic waves. We measured the frequency-dependent velocity data of longitudinal elastic waves in porous specimens and the dependence of the velocity dispersion on the kinematic viscosity of pore fluid. Moreover, we try to explain the velocity dispersion shown by the measurement data using the Biot theory. The Biot theory explains that the dispersion phenomenon is caused by the elastic property change in the media with the interaction between the solid phase and liquid phase, so the dispersion is dependent on the properties of liquid phase. The measurement data showed the phase velocities of longitudinal waves increased with an increase of frequencies and the characteristic frequencies which indicate the points of inflection moved to higher frequencies with an increase of kinematic viscosities of pore fluid. We report that we can estimate the kinematic viscosity of pore fluid in rock mass by using the dispersion curves which graphed the relation between the phase velocities and frequencies.

DOI： 10.2472/jsms.61.222

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In this study, a series of large-scale slope failure experiments with torrential rainfall was carried out and simulated using Discontinuous Deformation Analysis (DDA). Since DDA have not been coupled with flow calculation at present, the rainwater infiltration and rising groundwater level inside the slope was simulated separately using saturated-unsaturated flow analysis by Finite Element Method (FEM). The flow simulation results by FEM were incorporated in the DDA mechanical simulation as reduction of the shear strength and increase of the self weight. In the 2-D DDA model, octagonal blocks of 11.8 cm on average were used and rainfall boundary condition (steady rainfall of 100 mm/hour) was applied to the ground surface. The DDA simulation results were compared with the ones obtained from the rainfall experiments and the applicability of DDA to the slope failure/ collapse caused by torrential rainfall was also discussed. The simulation results also show that groundwater plays important roles for the failure process of soil mass, especially rainwater infiltration mechanism was significantly affected by unsaturated soil properties. © 2012 Taylor & Francis Group, London.

DOI： 10.1201/b11600-15

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

In this paper, the stability including stress distribution of two ancient masonry structures, the pyramid of the Pharaoh Khufu, Egypt and the Pont of Gard, were analyzed using discontinuous deformation analysis (DDA) and numerical manifold method (NMM). For the simulation using NMM, the newly developed four-node isoparametric element was used. The stress distributions/concentration were calculated and compared between the two methods. The calculated results show qualitative agreement with observations. DDA and NMM are applicable to simulate the physical phenomena of masonry structures.

DOI： 10.1142/S0219876211002575

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The multi-tank model is a helpful tool for rainfall-groundwater-runoff analysis since it can represent a nonlinear transport behavior and give predictions very quickly. On one hand, because of its simple and quick calculation, the tank model is useful in water table or stream flow prediction; on the other hand, by reason of its simplicity, its model error is relatively big, the model adjustment through the time variation is necessary. A new data assimilation methodology for online tuning of model parameters and states in the multi-tank model by taking into account new observations was developed, and important model parameters and states are retrieved simultaneously based on dual ensemble Kalman filter. A description of applying multi-tank model to simulate rainfall infiltration process in the slope is presented, and also the implementation of the dual ensemble Kalman filter approach for slope water table forecasting is demonstrated. Based on the observation data, the performance of the new method is studied. Finally, the factor of slope stability could be predicted based on filtered water tables. In this way, an early warning system of slope stability during rainfall could be built, which is helpful for disaster prevention.

DOI： 10.1007/s10346-010-0223-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Coupled hydro-mechanical processes in granular media represent the interaction between solid particles movement and fluid flow during external and/or internal loading. The processes attract attention in geotechnical engineering since they cause many disasters such as landslide, slope collapse, boiling/quicksand and soil liquefaction, etc. This study presents a numerical method combining discontinuous deformation analysis (DDA) for mechanical calculation and finite element method for fluid flow simulation to model the interaction between solid particles' movement and fluid flow from microscopic point of view. The term of hydraulic pressure was newly formulated and introduced to the original DDA. The simplified examples are given to verify the new method, and the computational results correlate well with the theoretical calculations, further development is also considered. Copyright (C) 2010 John Wiley & Sons, Ltd.

DOI： 10.1002/nag.890

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Publisher：Japan Society of Civil Engineers  

&nbsp;In order to evaluate the rainwate r storage and infiltration properties of the permeable pavement by unsaturated seepage analysis or gas-liquid two-phase flow analysis, it is important to know the unsaturated hydraulic properties of materials wh ich constitute the pavement. For this reason, we showed the unsaturated hydraulic properties of porous asphalt material s but we have not clarified the relation between the performance of the permeable pavement and the properties of all constituti on materials. In this paper, we try to determine the unsaturated hydraulic properties of subbase course and subgrade materials that greatly affect the rainwater storage and infiltration properties of the permeable pavement. We show from experiments that water retention characteristic and the un saturated hydraulic properties of subbase course and subgrade materials well match the van Genuchten model and the Irmay model.

DOI： 10.2208/jscejpe.67.120

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&nbsp;In order to estimate the permeable properties and pore fluid properties in the ground, survey methods using dispersion and attenuation of elastic waves have been developed. The Biot theory have been applied to the frequency-dependent dispersion data, but the influence of geological properties on velocity dispersion and the relation between the permeable properties and velocity dispersion in rock specimens have not become clear. Sedimentary rock and granite specimens were tested using longitudinal waves for the difference of velocity dispersion phenomena observed in each specimen, and we examine whether the Biot theory can be applied to observed experimental data. Moreover, we tried to estimate the permeability of the rock specimen based on the theory and show that the Biot-squirt theory can be applied to estimating rock permeability using the seismic wave dispersion characteristics.

DOI： 10.2208/jscejge.67.288

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

This paper describes the method that measures displacements from the three dimensional coordinate of the radio wave transmitter attached on the slope by the phase differences of received signals that were received by the receivers in the slope surroundings. Concretely, the special low power radio wave emitted by the transmitter on the slope was received by four or more receivers, and then the transmitter coordinates were calculated by an intersection of iso-phase-difference surfaces of each received signal. In the study, we consider the calculation method of the transmitters&rsquo; coordinate values and prove by the experiments that we can in real time measure the slope displacement with a high degree of accuracy by using devices with the radio wave of the frequency of 2.4GHz. We show that we can estimate the precision using GDOP that is determined by geometrical arrangement of the transmitters and receivers and verify the applicability of the proposed method in a real slope.

DOI： 10.3208/jgs.6.503

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&nbsp;In order to evaluate runoff control proper ties of three types of permeable pavements, namely, porous asphalt pavement, permeable interlocking concrete pavement and water-holding interlocking concrete pavement, experimentally obtaining permeability and water retentivity of each pavement material, this study conducted rainfall-runoff simulation of the three pavements using UNSA-2D, an numerical analysis program of saturated-unsaturated seepage flow. The input parameters of the numerical simulation were determined by fitting van Genuchten (VG) model or Irmay model into the experimental results. The simulation was performed under constant rainfall condition of three rainfall intensities and varying rainfall condition of center-peaked pattern. The results of numerical simulation revealed runoff characteristics of the three pavements, such as the temporal change in storage and infiltration with time, the runoff beginning time depending on the rainfall intensity and so on.

DOI： 10.2208/jscejpe.67.I_155

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We have studied the slope monitoring method using digital vision metrology. This study developed a technique for measuring the deformation of a slope without setting any fiducial points. The method of simply obtaining initial approximations of coordinate values from the images is applied to the new measurement technique. This measurement method has the advantage of obtaining the three coordinates of many measurement points at cheap cost. In this paper, the precision of the measurement values obtained by the proposed technology is verified in the actual rock slope. The feasibility based on the experimental results to the design of countermeasure construction is discussed.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Materials Science, Japan  

This paper introduces a new measurement system using digital images for tunnel construction management This measurement technique that utilizes digital images brings the following benefits compared with conventional techniques. The 3-dimensional deformations and the area-wide distributions of many measurement points can be obtained through simple measurement work. As the image data are all in digital format, real-time monitoring is possible. Measurement involves photographing from a distance only, eliminating the need for sophisticated techniques to improve accuracy as in conventional measurement The necessary measurement hardware consists of a digital camera and a PC only, which brings down measurement cost This study first attempts to establish the theoretical framework for using images photographed from any position with a digital camera for measuring any object for which is difficult to set fiducial points, such as a tunnel and reproduce the 3-dimensional displacement of a tunnel with considerable decision. It then goes on to clarify the relation between various measurement parameters and measurement decision and includes experiments to evaluate the performance of the technique that is applied to deformation measurement system of jointed rock masses. As a result the establishment of a new measurement system featuring simple measurement work and a high degree of decision was found to be possible. © 2010 The Society of Materials Science, Japan.

DOI： 10.2472/jsms.59.186

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Discontinuous Deformation Analysis (DDA) and Numerical Manifold Method (NMM) have been widely used for the analyses of discontinuous rock masses. Recently, these discontinuum-based numerical methods have been applied to the simulations for slope failure due to earthquakes, where one of the key issues is the estimation of traveling velocities and distances for the collapsed rock blocks. For the dynamic response analysis of rock slopes, it is necessary to consider the local variation of seismic forces, especially when the slope size is large and/or the slope geometry becomes complicated. In DDA, there is difficulty to consider the local displacements and stress condition of the single block for the basement because of mathematical principle (in DDA, the displacement function is defined at the gravity center of the blocks and the strain in the block is uniform). On the other hand, NMM can simulate both continuous and discontinuous deformation of the block systems. However, the rigid body rotation of blocks cannot be treated properly because NMM does not deal with the rigid body rotation in explicit form. According to the above-mentioned features and drawbacks, it is reasonable to combine DDA and NMM from practical point of view. In this paper, the formulation for the coupled NMM and DDA (NMM-DDA) was presented. For the formulation, NMM and DDA can be easily combined by choosing displacements of the DDA blocks and NMM cover nodes as unknowns, because the processes to establish the equilibrium equations (minimizing total potential energy) and kinematics for block system are same between DDA and NMM. In this paper, some applications of the NMM-DDA to both dynamic and static problems were also presented and the validity and applicability of newly developed DDA-MM were discussed. © 2010 World Scientific Publishing Company.

DOI： 10.1142/S021987621000209X

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&amp;nbsp;&amp;nbsp;In the DDA, the contact spring are introduced between the blocks contacting each other to prevent the penetration of the blocks but the dashpots are not usually introduced unlike DEM. However, it is well known that the numerical damping caused by numerical integration occurs during the simulations. In this study, the characteristics of numerical damping caused by Newmark &amp;beta; method in DDA was investigated using simple 1-D free oscillation problem. The 1-D collision problem was analysied using DDA with 3-D rigid sphere block and sensitivity analysis for the parameters related to Newmark &amp;beta; method was carried out. The effect of these parameters on the numerical stability and accuracy was also discussed. From the analytical results, in DDA, the calculation time step, &amp;Delta;&lt;i&gt;t&lt;/i&gt; and natural frequency, &lt;i&gt;T&lt;/i&gt; should satisfy the condition of &amp;Delta;&lt;i&gt;t/T&lt;/i&gt;&lt;0.05 to obtain the results with good accuracy. To evaluate the energy loss correctly when the two blocks collide each other, the effect of numerical damping and velocity ratio should be considered separately.

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&amp;nbsp;&amp;nbsp;A permeable pavement, which is one of pavements with various advanced functions, has been expected to improve the urban environments by the pervious surface structures. Because we need to determine the water retention and permeability characteristics of pavement materials in order to evaluate the rainfall storage and infiltration facilities of the permeable pavement, we conducted a series of laboratory tests using porous asphalt mixture specimens having a diameter of 150mm which consist of several different kinds of maximum grain size, void ratio and specimen length. The experimental results show that the Van Genuchten model predicts the water retention curves and the Irmay model predicts the unsaturated permeability coefficients of such materials very well, respectively.

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&nbsp;&nbsp;A permeable pavement, which is one of pavements with various advanced functions, has been expected to improve the urban environments by the pervious surface structures. Because we need to determine the water retention and permeability characteristics of pavement materials in order to evaluate the rainfall storage and infiltration facilities of the permeable pavement, we conducted a series of laboratory tests using porous asphalt mixture specimens having a diameter of 150mm which consist of several different kinds of maximum grain size, void ratio and specimen length. The experimental results show that the Van Genuchten model predicts the water retention curves and the Irmay model predicts the unsaturated permeability coefficients of such materials very well, respectively.

DOI： 10.2208/jsceje.66.452

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;&nbsp;In the DDA, the contact spring are introduced between the blocks contacting each other to prevent the penetration of the blocks but the dashpots are not usually introduced unlike DEM. However, it is well known that the numerical damping caused by numerical integration occurs during the simulations. In this study, the characteristics of numerical damping caused by Newmark &beta; method in DDA was investigated using simple 1-D free oscillation problem. The 1-D collision problem was analysied using DDA with 3-D rigid sphere block and sensitivity analysis for the parameters related to Newmark &beta; method was carried out. The effect of these parameters on the numerical stability and accuracy was also discussed. From the analytical results, in DDA, the calculation time step, &Delta;t and natural frequency, T should satisfy the condition of &Delta;t/T<0.05 to obtain the results with good accuracy. To evaluate the energy loss correctly when the two blocks collide each other, the effect of numerical damping and velocity ratio should be considered separately.

DOI： 10.2208/jscejc.66.299

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Language：Japanese   Publisher：The Society of Exploration Geophysicists of Japan  

&amp;emsp;The objective of this study is to establish a technique to obtain hydraulic conductivity distribution in granite rock masses. This technique is based on the characteristic that elastic wave velocity disperses in fully saturated porous media on frequency. Velocity dispersion is governed by fluid/solid interaction which corresponds to the hydraulic conductivity such as described by Biot and BISQ theory.&lt;br&gt; &amp;emsp;In order to verify the validity of these theories in granite rock, laboratory tests were performed. The results of experiments show that the elastic wave velocity dispersion for granite rock can be well described by BISQ theory. To test the applicability of this approach in real rock masses, we performed in-situ experiments at the Grimsel test site in Switzerland. Dispersion phenomena were detected in the frequency range from 0.8 kHz to 80 kHz, in the borehole distance range from 1.5m to 70m. Cross-hole tomography measurements, with frequency at 20 kHz and 40 kHz in a distance between boreholes of 1.5 meter, were carried out.&lt;br&gt; &amp;emsp;To obtain the hydraulic conductivity image, geostatistical technique was tried. A limited number of hydraulic test data were used to find the correlation between the velocity difference and hydraulic conductivity. With this correlation, a hydraulic conductivity image was constructed. The location of the high hydraulic conductivity zone from the result agrees with that estimated using geological information. Additional hydraulic tests were conducted in a borehole located in the middle of the tomography plane. These hydraulic tests show a good agreement between the measured hydraulic conductivity and the hydraulic conductivities predicted from the cross-hole tomography.&lt;br&gt; &amp;emsp;These result of experimental studies show that the possibility as a practical method to determine the hydraulic conductivity image in granite rock.&lt;br&gt;

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Language：Japanese   Publisher：The Society of Exploration Geophysicists of Japan  

&emsp;The objective of this study is to establish a technique to obtain hydraulic conductivity distribution in granite rock masses. This technique is based on the characteristic that elastic wave velocity disperses in fully saturated porous media on frequency. Velocity dispersion is governed by fluid/solid interaction which corresponds to the hydraulic conductivity such as described by Biot and BISQ theory.<br> &emsp;In order to verify the validity of these theories in granite rock, laboratory tests were performed. The results of experiments show that the elastic wave velocity dispersion for granite rock can be well described by BISQ theory. To test the applicability of this approach in real rock masses, we performed in-situ experiments at the Grimsel test site in Switzerland. Dispersion phenomena were detected in the frequency range from 0.8 kHz to 80 kHz, in the borehole distance range from 1.5m to 70m. Cross-hole tomography measurements, with frequency at 20 kHz and 40 kHz in a distance between boreholes of 1.5 meter, were carried out.<br> &emsp;To obtain the hydraulic conductivity image, geostatistical technique was tried. A limited number of hydraulic test data were used to find the correlation between the velocity difference and hydraulic conductivity. With this correlation, a hydraulic conductivity image was constructed. The location of the high hydraulic conductivity zone from the result agrees with that estimated using geological information. Additional hydraulic tests were conducted in a borehole located in the middle of the tomography plane. These hydraulic tests show a good agreement between the measured hydraulic conductivity and the hydraulic conductivities predicted from the cross-hole tomography.<br> &emsp;These result of experimental studies show that the possibility as a practical method to determine the hydraulic conductivity image in granite rock.<br>

DOI： 10.3124/segj.62.307

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Other Link： http://hdl.handle.net/2433/153401

Language：Japanese   Publisher：Japan Society of Civil Engineers  

&amp;nbsp;&amp;nbsp;To investigate the discontinuous behaviors of rock slopes/masses after collapse of the rock slope caused by the earthquake, the discontinuum based approach is necessary. In this study, the earthquake response analysis for discontinuous blocks was performed by Discontinuous Deformation Analysis (DDA) with a single block and multilayer block models. The results obtained from the simulations by DDA were compared with the analytical solutions and results from the laboratory shaking table tests. We investigated the applicability of DDA to seismic problems. It was found that DDA is powerful tool to analyze seismic response for both simple block and multilayer block models.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In the DDA (Discontinuous Deformation Analysis), the ratio of velocity energies (squared velocity ratio) is used for the energy loss during collision. The velocity ratio is investigated in detail with the experiments. It was clear that the velocity ratio is dependent on the incident velocity of the normal direction. Therefore, velocity ratio is not appropriate to consider the property as a direct input value of the simulation. However, we have clarified that it is possible to perform a rockfall simulation by considering the velocity-dependence of the velocity ratio in the application of DDA by using the &amp;ldquo;Scale Factor&amp;rdquo; as proposed by Pfeiffer et al. (1989).

DOI： 10.2208/jscejc.65.53

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

We study the numerical index of rock shape in order to improve the procedure for the determination of geometric parameters in the rock fall simulation using discontinuous deformation analysis. Aspect ratio, roundness and shape entropy are examined as the index of rock shape characteristics through the simulation of simple-bouncing case, multiple-bouncing case and actual rock fall failure case. Results of these simulations indicate that roundness and shape entropy of curvature are the practical index corresponding to the behavior of falling block in the simulation, i.e., variation of exit angle in single-bouncing process and energy loss in multiple-bouncing process. It is thought that applying these indexes to the rock fall simulation is effective for reducing subjective error in recognizing characteristics of rock shape and improving accuracy of the rock fall simulation.

DOI： 10.3208/jgs.4.357

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;&nbsp;This paper describes the simulation method to explain the mechanism of the permeability characteristics of specimens with single discontinuties under shear through shear-flow coupling tests, showing that on the shear stress-displacement curve obtained by the constant normal load testing, the water flowing through the discontinuties have different transmissibility-aperture width relation before or after the yield range. As a technique to serve this purpose, the lattice gas automaton method, which is to substitute the fluid with particles and repeat letting them collide. With this technique, the factors of surface structure of discontinuties that determine the shear/permeability characteristics are identified.

DOI： 10.2208/jscejc.65.776

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;&nbsp;To investigate the discontinuous behaviors of rock slopes/masses after collapse of the rock slope caused by the earthquake, the discontinuum based approach is necessary. In this study, the earthquake response analysis for discontinuous blocks was performed by Discontinuous Deformation Analysis (DDA) with a single block and multilayer block models. The results obtained from the simulations by DDA were compared with the analytical solutions and results from the laboratory shaking table tests. We investigated the applicability of DDA to seismic problems. It was found that DDA is powerful tool to analyze seismic response for both simple block and multilayer block models.

DOI： 10.2208/jscejc.65.644

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&amp;nbsp;&amp;nbsp;This paper describes the simulation method to explain the mechanism of the permeability characteristics of specimens with single discontinuties under shear through shear-flow coupling tests, showing that on the shear stress-displacement curve obtained by the constant normal load testing, the water flowing through the discontinuties have different transmissibility-aperture width relation before or after the yield range. As a technique to serve this purpose, the lattice gas automaton method, which is to substitute the fluid with particles and repeat letting them collide. With this technique, the factors of surface structure of discontinuties that determine the shear/permeability characteristics are identified.

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

We study the numerical index of rock shape in order to improve the procedure for the determination of geometric parameters in the rock fall simulation using discontinuous deformation analysis. Aspect ratio, roundness and shape entropy are examined as the index of rock shape characteristics through the simulation of simple-bouncing case, multiple-bouncing case and actual rock fall failure case. Results of these simulations indicate that roundness and shape entropy of curvature are the practical index corresponding to the behavior of falling block in the simulation, i.e., variation of exit angle in single-bouncing process and energy loss in multiple-bouncing process. It is thought that applying these indexes to the rock fall simulation is effective for reducing subjective error in recognizing characteristics of rock shape and improving accuracy of the rock fall simulation.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The permeable pavement was attracted as a method of a city environmental improvement. It was introduced to subsidence occurred by pumping ground water. Application on a heavy traffic road is also considered now in connection with a recent law about control runoff in urban area. However, problems which should be solved, such as the durability, remain to apply permeable pavements on the heavy traffic road. This paper is discussed about the durability of a permeable pavement etc. from the results of the follow-up survey over about 13 years of the national highway by which test construction of the permeable pavement was carried out in Japan on the heavy traffic road in 1993.

DOI： 10.2208/jsceje.64.276

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Publisher：Japan Society of Civil Engineers  

This paper presents a tunnel deformation measurement technique by using digital images taken from a moving car. Because the three-dimensional coordinate of each target installed on tunnel wall can be calculated through photogrametric analysis, it is possible to obtain the positions of the pairs of targets whose distances represent the crown settlement and convergence. This paper summarized the results of experiments performed to verify measurement precision. As a result, the coordinate values of targets with a high degree of precison can be obtained from the geometric constraint conditions of the geodetic network without having to set any fiducial points. Based on this study, this paper argues the practicability of the proposed technique in the tunnel maintenance phase.

DOI： 10.2208/jscejc.64.598

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Publisher：Japan Society of Civil Engineers  

The permeability design in the design method of a permeable pavement makes the trial calculation of the road metal and pavement thickness to be used so that the permeavility capability demanded according to an application part may be satisfied. It is determined as compared with the structure required in a structural design. Saturated hydraulic conductivity is estimating the permeable ability in that case. However, the rainfall initial permeates in the state where a inside of pavement is unsaturated. Then, this research measured the water retention characteristics of a permeable pavement.

DOI： 10.2208/journalpe.13.63

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Language：Japanese   Publisher：日本ヒートアイランド学会事務局  

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Publisher：Japan Society of Civil Engineers  

The permeability design in the design method of a permeable pavement makes the trial calculation of the road metal and pavement thickness to be used so that the permeavility capability demanded according to an application part may be satisfied. It is determined as compared with the structure required in a structural design. Saturated hydraulic conductivity is estimating the permeable ability in that case. However, the rainfall initial permeates in the state where a inside of pavement is unsaturated. Then, this research measured the water retention characteristics of a permeable pavement.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The permeable pavement was attracted as a method of a city environmental improvement. It was introduced to subsidence occurred by pumping ground water. Application on a heavy traffic road is also considered now in connection with a recent law about control runoff in urban area. However, problems which should be solved, such as the durability, remain to apply permeable pavements on the heavy traffic road. This paper is discussed about the durability of a permeable pavement etc. from the results of the follow-up survey over about 13 years of the national highway by which test construction of the permeable pavement was carried out in Japan on the heavy traffic road in 1993.

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

We have been studying the slope monitoring method using digital vision metrology. This study developed a technique for measuring the deformation of a slope using this measurement without setting any fiducial points and with the method of simply obtaining initial approximations of coordinate values from the images taken. This measurement method has the advantage of obtaining the three coordinates of many measurement points at cheap cost. In this paper, the precision of the measurement values obtained by the proposed technology is verified in the actual rock slope and we discuss its feasibility based on the experimental results of application of the measurement values to the design of countermeasure construction.

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Language：Japanese  

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Language：Japanese   Publisher：The Japanese Geotechnical Society  

We have been studying the slope monitoring method using digital vision metrology. This study developed a technique for measuring the deformation of a slope using this measurement without setting any fiducial points and with the method of simply obtaining initial approximations of coordinate values from the images taken. This measurement method has the advantage of obtaining the three coordinates of many measurement points at cheap cost. In this paper, the precision of the measurement values obtained by the proposed technology is verified in the actual rock slope and we discuss its feasibility based on the experimental results of application of the measurement values to the design of countermeasure construction.

DOI： 10.3208/jgs.3.109

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Publisher：Japan Society of Civil Engineers  

This paper presents a tunnel deformation measurement technique by using digital images taken from a moving car. Because the three-dimensional coordinate of each target installed on tunnel wall can be calculated through photogrametric analysis, it is possible to obtain the positions of the pairs of targets whose distances represent the crown settlement and convergence. This paper summarized the results of experiments performed to verify measurement precision. As a result, the coordinate values of targets with a high degree of precison can be obtained from the geometric constraint conditions of the geodetic network without having to set any fiducial points. Based on this study, this paper argues the practicability of the proposed technique in the tunnel maintenance phase.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：COAL INDUSTRY PUBL HOUSE  

This paper deals with the relevance of numerical modeling with respect to mechanical properties of rock proposed, and discusses the applicability of rock fall simulation by using discontinuous deformation analysis (DDA). In order to foresee collapse of rock slope, numerical method will be extremely useful. However, it will be difficult to simulate collapsed, considering difficulties of rock parameter, such as geology, fracture, fault and laboratory testing into numerical calculation. We present the way to modeling the jointed rock mass to evaluate the rock slope instability, and a simulated result for an actual rock mass collapse are shown. Furthermore, it was discussed that the applicability of rock fall simulation by using DDA for numerical experiments and the investigation of rock fall in the northern part of Japan. In order to predict the behavior of rock fall, the energy loss model considering collision has been built in the original DDA. The energy loss caused by slope absorbability can be clarified in this model. The improved DDA is supposed to be very useful for rock fall analysis and measures design.

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Language：Japanese   Publisher：電力土木技術協会  

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Language：Japanese   Publisher：日本写真測量学会  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This paper developed a rock fall simulation by using discontinuous deformation analysis (DDA). In the simulation, the energy loss of rock fall was expressed respectively in response to every movement feature of rock fall by using absolute parameter. The energy losses of the rock fall were categorized to three forms of the energy loss in friction, the energy loss considering collision and the energy loss by vegetation. The energy loss model by using absolute parameter have been built in the DDA method. Additionally, using the improved DDA, the simulation of field rock fall experiments was performed. The results of the movement feature, velocity and the jump height of the rock fall were in good agreement with the field experiment. Herewith, the new technique considering the slope absorbability, vegetation condition and shapes of the falling rock block has been established a new methodology for design of road disaster prevention of rock falls.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Hazard maps support effective disaster management of rock mass failure. In this study we compiled reliability prediction charts of hazard areas caused by rock mass failure debris, which are the basis of hazard maps. In addition to the predicted debris hazard areas, we took into account other factors such as rock slope stability and the effects of countermeasures obtained from published data to prepare hazard maps for risk assessment. Applying map-based risk assessment to rock mass failure allowed us to visually identify risks by size, location, and section, consequently enabling reasonable logical judgment from a broad perspective in setting priorities for countermeasures and inspections against rock mass failure.

DOI： 10.2208/jscejc.63.901

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Publisher：Japan Society of Civil Engineers  

Photogrammetry is the technique to measure the form of 3-dimensional objects by analyze the pictures of reflective targets on the objests. Conventional measures need three divices to measure the 3-D deformations, however Photogrammetry can measure the deformations by one device. We tried to apply this technique for measuring 3-D deformation of a concrete structure under the cyclic load. The expected failure mode is due to buckling of enclosed reinforcements. 3-D deformations are necessary to clarify the behavior of specimen. As the results, it was possible that this technique has an accuracy and can visualize the process of deformation.

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Language：Japanese   Publisher：The Society of Materials Science, Japan  

In order to understand and model relations between microstructure of rocks and their physical properties, uniaxial tension tests were conducted on specimens of nine granitic rocks included a granite, four granodiorites and four tonalities, and two gabbros which were taken from eastern Japan. The axial and transversal deformability of these rocks was determined based on strain measurements using wire strain gauges. The experimental test results revealed that deformational properties of the rocks investigated varied depending on their petrographic features. However, the axial strain and the lateral strain characteristics showed a similar trend for all the rocks, i.e. the stress-strain curves were non-linear throughout the whole stress range from the initial point of loading to the point of ultimate failure. Moreover, the tangent Young&#039;s modulus and the ratio of the lateral strain to the axial strain decreased monotonously with the increasing of the axial stress. Still, the deformational properties were different for individual rocks in a quantitative sense. In particular, the difference in the lateral strains among different rocks was more distinct than that in the axial strains. For example, the Poisson&#039;s ratio at a stress level equal to 50% of the ultimate strength of a granodiorite was very low, close to zero. Furthermore, the Poisson&#039;s ratio of a tonalite was lower than that of a granodiorite, and assumed a negative value. This effect occurred because the lateral strain became positive as it changed from contraction at the initial stage of loading to extension at higher stress levels. There is no ready explanation for this phenomenon; it is believed, however, that it occurs due to microcracks pre-existing in rock materials and/or weak bonds between the adjacent mineral grains.

DOI： 10.2472/jsms.56.654

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Publisher：Japan Society of Civil Engineers  

The rainfall storage and infiltration facilities of permeable pavements have been attracted attention as an improvement measure of urban environment. In this paper, experimental study makes clear that rainfall infiltration facilities of permeable pavements are strongly dependant on rainfall intensity and unsaturated zones prevent rainfall from infiltrate into the pavement. We develop the simulation method that analyze the air and seepage flow simultaneously and we demonstrate that the dependence of rainfall infiltration facilities on rainfall intensity is mainly caused by the behavior of air flow in the pavement. It is shown that the effects of permeable pavements on flood control can be evaluated accurately by using this simulation method.

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Publisher：Japan Society of Civil Engineers  

The permeable pavements are mainly constructed for the purpose of cultivating ground water and mainly applied on the sidewalk. It was admitted that permeability was effective for flood which increases rapidly in the city. And application on a heavy traffic road is also considered now in regarding to a recent law about control runoff. Therefore, test constructions are tried in various places. However, it is necessary to solve problems, such as durability, to apply permeable pavements to the roadway. Especially, aggregates of granular materials moves by infiltration of rain water and the quality have been changed. This paper verified the quality change of granular materials by the infiltration of rain water.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In order to understand the mechanical and permeable properties of rock masses for construction of underground structures, shear-flow coupling tests of specimens having a single rock joint were performed under constant normal stiffness conditions. In the tests, how the permeable properties depend on various physical parameters, such as normal stress, joint surface roughness and hydraulic gradient, were examined. The results show the relationship between the mechanical and permeable properties of rock joints in relation to pore structures created by surface roughness under shear process.

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Publisher：Japan Society of Civil Engineers  

Photogrammetry is the technique to measure the form of 3-dimensional objects by analyze the pictures of reflective targets on the objests. Conventional measures need three divices to measure the 3-D deformations, however Photogrammetry can measure the deformations by one device. We tried to apply this technique for measuring 3-D deformation of a concrete structure under the cyclic load. The expected failure mode is due to buckling of enclosed reinforcements. 3-D deformations are necessary to clarify the behavior of specimen. As the results, it was possible that this technique has an accuracy and can visualize the process of deformation.

DOI： 10.2208/journalac2003.16.0_149

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Language：Japanese  

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Language：Japanese   Publisher：The Society of Materials Science, Japan  

Various kinds of measurements were carried out during excavation of two large underground caverns to estimate rock behavior as a discontinuous material. As a result, rock behavior as a discontinuous material was estimated in detail, such as characteristics of crack propagation, displacement and stress redistribution. In particular, it was found that characteristics of displacement and stress redistribution were very remarkable in some areas and that crack propagation was also remarkable in the area. Through the measurements, it was suggested that the sliding of discontinuities were related to the discontinuous behavior. So with a simulation in which the discontinuities were modeled, the influence of the sliding of the discontinuity to crack propagation, displacement and stress redistribution is discussed.

DOI： 10.2472/jsms.55.501

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Publisher：Japan Society of Civil Engineers  

In these days, some attempts have been made at the improvement of heat environment in urban area by constructing permeable pavements in carriageway area. We have tried to establish the measuring method of evaporation from permeable pavements. And also, we have conducted experiments and have measured evaporation, temperature and volumetric water content on the permeable pavement model, which structure is the same as that of Route 163, in order to examine the effectiveness of permeable pavements. The results show that the proposed method can be useful and evaporation contributes to lower surface temperature of permeable pavements.

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Language：Japanese   Publisher：Japan Society of Geoinformatics  

We report the study on the evaluation method of ground classification ahead of tunnel face using drilling data such as drilling speed, specific drilling energy and damping pressure and discuss the applicability of the drilling survey system to the tunnel construction field. Moreover, the neural network system on the basis of a learning data has been introduced to analyze the drilling data automatically and objectively. We demonstrate the advantage of the drilling survey system making a precise decision of ground classification without human experiences from the experimental results.

DOI： 10.6010/geoinformatics.16.191

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Language：Japanese   Publisher：土木学会  

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Language：Japanese   Publisher：Japan Society of Engineering Geology  

For the purpose of understanding the hydraulic behaviours of rock joints undergoing shear deformations, the shear-flow coupling experiments were performed. The results indicated that the macrosopic permeable characteristics are greatly affected by the microscopic structures of joint surface, and the cubic law, which is popularly used for permeability characteristics evaluation, cannot be applied where the mechanical aperture width is small in the early stage of shearing. In order to evaluate the relationship between fluid flow phenomena and aperture distribution in a rock joint, the numerical analysis based on Lattice Gas Automaton (LGA) was applied to simulate complicated microscopic flows produced by the complex boundary conditions. It was possible by the simulation method to explain the hydraulic behaviours in shear-flow coupling experiments by fluid-wall boundary interaction when water flows through a rock joint.

DOI： 10.5110/jjseg.45.291

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASCE - American Society of Civil Engineers  

A three-dimensional (3D) rock slope toppling occurred in a discontinuous rock mass. To simulate the failure process and study the mechanism of this rock failure with contact and large displacement in 3D, a new discrete numerical method has been developed called the 3D discontinuous deformation analysis (DDA). This article first introduces the basic principles and then derives the formulas in detail. Finally, the slope failure simulation is applied as an example to investigate the applicability of this new method to rock slope failure research. The simulation results indicate the advantages of using this new method to study the mechanism of a rock slope failure with 3D behavior. International Journal of Geomechanics © ASCE.

DOI： 10.1061/(ASCE)1532-3641(2005)5:3(179)

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Language：Japanese   Publisher：土木学会  

The paper presents a photogrammetric system with a digital camera as a precise measuring tool for the monitoring of slope stabilities. The least squares solution with a pseudoinverse method, which has the advantage of the flexibility of measurement, is introduced by both of mathematic and geometric concepts to transform two dimensional digital image coordinates into three dimensional object space coordinates without the incorporation of control data. In the paper, experiments have been also conducted to quantitatively examine the accuracies and precision of this solution, and the results show that this measurement system has high potential applicability in deformation monitoring of a slope.

DOI： 10.2208/jscej.2004.771_187

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Language：Japanese   Publisher：Japan Society of Engineering Geology  

In each country of Southeast Asia, there has been lots of slope hazard including a landslide and a slope collapse caused by the geological feature condition and climate condition, and rapid city development will increases the disaster in the future. However, the technology about city protection against disasters in these countries has been undeveloped technically. Authors have been developing a monitoring method of slope behaviors by using digital photogrammetry. Photogrammetry is defined as a measuring technique constructing the modeling of a three-dimensional (3D) space using two-dimensional (2D) images. Photogrammetry has the advantage of measuring deformation of an object by some photos with excellent cost performance. This paper proposes that many engineers are able to carry out photogrammeric work without reliance on photogrammeric technicians and shows that photogrammetry has the advantage of measuring deformation of a slope by some photos with easy measurements. When measurements are performed without control points, the normal-equation matrix has a rank deficiency of 7 depending on the three translations, three rotations and the scale in the network of observations. In order to eliminate the rank deficiency of the normal-equation matrix we must find seven additional equations. We present the geometrical analysis for the problem to measure the three-dimensional coordinates of measurement points without control points. This paper also shows a numerical method for calculating sufficiently good initial approximate values. This performance is suitable for a monitoring tool used for a protection against slope hazard in Southeast Asia. This digital photogrammetric system can remove human skills in measurement tasks, so it is possible to use it immediately when necessary. The applicability of digital photogrammetry is discussed with its accuracies in Taiwan. Recently there are a lot of constructed roads passing through the soft rock areas in Taiwan. The main formation of soft rock in this country includes sandstones, shale, and mudstone. Due to the poor engineering properties of soft rock, there are many slope hazards along the road. The digital photogrammetry demonstrates that our method has a high potential to prevent the slope hazards in Southern Asia.

DOI： 10.5110/jjseg.44.331

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Language：Japanese   Publisher：土木学会  

In this paper, the effect of the uncertainties associated with the spatial distribution of rock fractures on the evaluation of loss due to slope failure was discussed. In detail, in order to model the spatial distribution of rock fractures based on stochastic approach, the methodology related to fracture network model was adopted. Finally, the conclusion made it obvious that the results associated with the evaluation of loss are more seriously affected by the spatial distribution of rock fractures, comparing with the effect of other parameters on the results.

DOI： 10.2208/jscej.2003.736_231

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Language：Chinese   Publishing type：Research paper (scientific journal)  

Numerical simulations are very important to the disaster preventions in rock slope engineering, and many researchers pay attention to the developments and applications of numerical analysis methods in this field recently, because of the developments of computer science. In order to simulate the behaviors of rock slopes with discontinuities more precisely, the numerical method is required to consider the effects of distributions of discontinuities, terrains, contacts among blocks and the large displacements in three dimensions. In this paper, both the theory of three dimensional discontinuous deformation analysis(3D DDA) and its application to simulate rock slope failure problems are discussed. DDA belongs to the discrete numerical analysis methods, and the contact judgment and contact force computation should be concerned. The contact forces are produced when blocks contact to each other. Usually, normal contact spring is employed to calculate the normal contact forces to prevent blocks from penetrating to each other during contacts, and the normal contact spring is deleted when blocks are leaving. In addition, the failure along discontinuous surfaces can be simulated easily by applying the Mohr-Coulomb failure criterion. The appropriate contact spring arrangement in 3D DDA follows the criterion of no-penetration and no-tension to obtain correct contact forces during contacts. The new approach has been successfully applied to simulate a rock slope toppling at Amatoribashi-nishi site in Japan. The simulation results are quite good in agreement with the video pictures obtained from the field. It is believed that the simulation is very helpful on investigation of the failure mechanism and process, and can provide useful knowledge to study the similar events in future.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Materials Science Japan  

Because deformations are important indicators of the degree of stability during construction of rock structures, monitoring of deformation is a key element of observational method in tunnels. Monitoring can also help determine the depth of the loosened zone, movements on discontinuities, in-situ modulus, and other items that may be dealt with in design. We have studied the applicability of digital photogrammetry for monitoring of surface displacements in civil engineering. Digital Photogrammetry is the technique obtaining three dimensional coordinates of an object by means of digital photography. This photogrammetry has the advantage of measuring deformation of an object by some photos with easy measurements and excellent cost performance. Because the linearized equation to analyze the coordinates of object points has some rank defects due to no control points in tunnel, we present constrained least square estimation to measure the displacements without the incorporation of control point configuration. The results of experiments demonstrated that this measurement system could yield high accurate three dimensional coordinates of target points situated on an object. It is also shown that this digital photogrammetry can monitor the displacements of the tunnel accurately along with a capability of real-time measurement because of removal of human skills in measurement tasks.

DOI： 10.2472/jsms.52.1006

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this paper, a shearing test was carried out under constant normal stiffness condition to understand the mechanical characteristics of discontinuities. By using the result of this test, we propose an efficient methodology to estimate the strength parameters &lt;i&gt;c&lt;/i&gt; and &amp;phi;, in case we assume the strength characteristics of discontinuities follow the Mohr-Coulomb&#039;s failure criterion. In addition, we discuss the effect of parameters such as roughness, initial normal stress and normal stiffness on the shearing behavior of discontinuities by comparing the results between the shearing test under constant normal stiffness condition and constant normal stress condition.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Materials Science Japan  

In this paper, both the theory of Three-Dimensional Discontinuous Deformation Analysis (3D DDA), and its application to simulate rock slope failure problems are discussed. DDA belongs to one of the discontinuous numerical analysis methods, and the contact judgment and contact force computation should be concerned to produce contact forces when blocks contact to each other. It is shown that a normal contact spring is employed to calculate the normal contact forces to prevent blocks from penetrating to each other during contacts. However, the normal contact spring is deleted when blocks are leaving. In addition, the failure along discontinuous surfaces can be simulated easily by applying the Mohr-Coulomb failure criterion. The appropriate contact spring arrangement in 3D DDA follows the criterion of "No-penetration and No-Tension" to obtain correct contact forces during contacts. The new approach has been successfully applied to simulate a rock slope toppling at Amatoribashi-nishi site in Japan. The simulation results are quite in agreement with the video pictures obtained from the field. We believe that the simulation is very helpful on investigation of the failure mechanism and process, which can provide useful knowledge for study such events in future.

DOI： 10.2472/jsms.52.488

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Language：Japanese   Publisher：Society of Materials Science Japan  

In tunnel constructions, heterogeneity of rock bodies such as faults and related fracture zones can be serious problem for safety management, construction planning and excavation costs. Thus, the estimate of geological conditions and rock properties ahead of the tunnel faces is strongly required and several methods of such fore survey have been proposed by many researchers. For this purpose, we have developed "DRISS", the Drilling Survey System, for fore surveys at tunnel faces with higher accuracy, and report here the application of this system to tunnel construction sites. In this paper, we outline our fore survey system, and show the successful fore survey results including the improvement in drilling techniques at the tunnel construction site with soft rocks.

DOI： 10.2472/jsms.52.494

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Society for Rock Mechanics  

The behaviors and stress distributions of the inclined jointed rock masses with different dip angles obtained from DDA are compared to the results of laboratory tests. By calculating the block stress distributions, it is confirmed that DDA can reproduce the arching around the trap door when lowering the trap door. The shapes of arching change with the angles of inclined layers. In addition, the earth pressures acting on the trap door shows non-symmetrical distributions when the layers are not horizontal. The stress concentration occurs in one side of the rock masses close to the trap door. Furthermore, the surface settlements are also related to the inclined angle, and the loosening zone in rock masses can be different from Terzghi's theory [1]. Since, simulations have good agreements with the laboratory test, it demonstrates the applicability of DDA to explain the mechanical behaviors of tunnel, such as arching phenomenon, non-symmetrical earth pressure distributions acting on the trap door, and the surface settlement profile in the jointed rock masses.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

It has been known that the mechanical behavior of rock mass strongly depends on these of discontinuities such as faults, fractures and joints. In the rock mechanics literature, several constitutive models to predict joint shear strength have been proposed focusing on effect of geometrical properties of the joint surface roughness. It is shown, however, that some of existing models have problems that these do not quantitatively reflect on geometrical properties. In our study, the statistical parameter related to the strength properties obtained from the results of the direct shear experiments is introduced and a new constitutive model to predict shear strength of rock joint is proposed.

DOI： 10.2208/jscej.2002.722_59

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Language：Japanese   Publisher：土木学会  

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The separation of rigid body rotation term, r&lt;SUB&gt;0&lt;/SUB&gt;, from the other displacement variables is a breakthrough idea in original discontinuous deformation analysis (DDA) formula. Although the original linear displacement function is a fast and efficient method in computation, it loses accuracy when blocks undergo large rigid body rotations. It can be a significant problem especially when solving the problem with high speed rigid body rotation, such as rock fall problem, or the larger time interval is introduced to the problem with rigid body rotation to obtain the results within less computation steps. Up to date, it is only known that the large rigid body rotation can cause free expansion and change the weight of block in the analysis. However, the authors consider that the problem can also affect the contact judgments in open-close iterations and cause wrong contact forces in the computation. In this paper, this problem will be discussed, and a new method named &amp;ldquo;post contact adjustment&amp;rdquo; is developed and applied to the contact computation terms of DDA. After the improvements, the simulation results show better contact computations and block area preservations even when the large rigid body rotation is carried out.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

We examined the azimuthal distributions of circumferential strain, radial deformation, and &lt;i&gt;V&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt;, &lt;i&gt;V&lt;sub&gt;s&lt;/sub&gt;&lt;/i&gt;&amp;para;, and &lt;i&gt;V&lt;sub&gt;s&lt;/sub&gt;&lt;/i&gt;&amp;perp; of seismic waves traveling through a specimen of granite as it was deformed to faulting under the uniaxial conditions. All measurements were made within the plane perpendicular to the loading axis. It is concluded that anisotropy in physical properties of granite arises from the inherent microcrack fabric and anisotropic ordered alignment of microcracks extended or produced during loading (dilatancy-induced-fabric). Dilatancy anisotropy is much higher than anisotropy due to the natural fabric. The symmetry of physical properties can be characterized by the symmetry of dilatancy-induced-fabric. Based on the Neumann&#039;s principle in crystallography, we can simulate the mechanical behavior of granite with dilatancy-induced-fabric as an orthorhombic crystal.

DOI： 10.2208/jscej.1987.382_63

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Language：Japanese   Publisher：土木学会  

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Language：Japanese   Publisher：総合土木研究所  

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Language：Japanese   Publisher：土木学会  

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Recent years have seen reports of rock collapses and rock-falls from steep slopes, even if such points have not been extracted as those requiring inspection. In the maintenance of steep slopes, it is important to confirm the presence of rock-falls and source rocks corresponding to the outlined survey; however, it can be difficult to investigate from the target structure to the vicinity of the ridge because of cost concerns and vegetation overgrowth. It is important to obtain detailed geographical information for an efficient overview survey; therefore, laser measurement technologies with significant performance improvements have been used in the field of slope disasters including public surveys and the study of landslides, and it is expected that the utility of these technologies will further increase. Herein, multiple combinations of airborne and ground-based laser measurement technologies were used to study steep slopes facing a river. Fluctuation analysis was performed using three-dimensional (3D) point cloud data obtained via laser measurements. As a result, airborne laser measurements deciphered 1.5-m high scarplets. Furthermore, by conducting displacement vector analysis, we grasped the tendency of fluctuation that gradually increased from the mountain to the river. In addition, for the overhanging blocks closest to the river, we detected an average variation of 141 mm via displacement vector analysis using a terrestrial laser scanner (TLS) with a 2-m mesh. We report the evaluated behavior of steep slopes depending on the type of topography and geology and the effectiveness of the technology as a periodic measurement method for maintenance purposes.

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Language：Japanese   Publisher：日本測量協会  

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Language：Japanese   Publisher：National Committee for IUTAM  

<p>Soft and heterogeneous ground is widely distributed in Japan. When embankment is built on soft ground, it is necessary to conduct ground survey and set ground improvement range. The ground improvement range is determined by analysis simulation, and various parameters are necessary for analysis. In this research, we discuss the difference of results by analysis parameters set from the ground survey results.</p>

DOI： 10.11345/japannctam.64.0_OS6-05

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Language：Japanese   Publisher：National Committee for IUTAM  

&lt;p&gt;Soft and heterogeneous ground is widely distributed in Japan. When embankment is built on soft ground, it is necessary to conduct ground survey and set ground improvement range. The ground improvement range is determined by analysis simulation, and various parameters are necessary for analysis. In this research, we discuss the difference of results by analysis parameters set from the ground survey results.&lt;/p&gt;

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Language：Japanese   Publisher：Japan Society of Engineering Geology  

&lt;p&gt;Airborne laser measurement has been widely known as a surveying technique for acquiring topographic data with a high accuracy, and it has been lately utilized as a differential analysis for evaluating the amount of the sediment caused by a large-scale landslide. However, it is impossible to detect landslide behavior at speed of a few centimeters using aerial laser measurement. In this study, we have developed the analytic method to evaluate landslide variation amount with a high accuracy by discriminating characteristic land features from digital elevation model, which is called S-DEM or Substratum Digital Elevation Model, using laser point clouds at the position shifted from the ground with an arbitrary distance. We also describe the result that it is possible to predict the movement of debris slide occurred in the area of landslide using the method we developed.&lt;/p&gt;

DOI： 10.5110/jjseg.57.277

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Language：Japanese   Publisher：高速道路調査会  

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