研究者詳細 - 西村　伸一

論文 - 西村　伸一

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A study of the measurement of fracture toughness in cohesive soil - relationship between the size of initial crack and diameter of specimen 査読

Shin-ichi Nishimura, Hideyoshi Shimizu

PADDY AND WATER ENVIRONMENT 2 ( 1 ) 27 - 32 2004年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER HEIDELBERG

The phenomenon of hydraulic fracturing is considered to be one of the causes of leakage in fill-type dams. In recent years, it has been found that an estimate of the fracture toughness of a given type of soil could be used as an indicator of the soil's resistance to hydraulic fracturing. One of the problems encountered in its estimation is the assumption that fracture toughness has been theoretically defined for samples of infinite sizes. In this study, laboratory tests were conducted to determine the fracture toughness of samples (of the same size) prepared with initial cracks of various lengths. The main objective was to investigate the relationship of the initial crack length to fracture toughness. The stress distribution around the crack tip for each laboratory test sample was estimated by FEM analysis and by a theoretical equation. These analytical results corresponded reasonably well to results from laboratory tests to determine the appropriate length of the initial crack for the test specimens.

DOI： 10.1007/s10333-004-0036-5

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コスト最小化理論に基づく液状化対策工最適設計

西村伸一, 清水英良

農業土木学会誌 72 ( 5 ) 17 - 20 2004年

クリープ現象の数理モデル査読

西村伸一, 堀俊男, 藤井弘章

日本地すべり学会誌 41 ( 2 ) 105 - 109 2004年

分割型圧密試験による粘性土の時間依存性挙動に関する考察

西村伸一, 日高健寿, 村山八洲雄

地盤工学研究発表会発表講演集 39 205 - 206 2004年

出版者・発行元：公益社団法人地盤工学会

分割型圧密試験機は,圧密試料内部のひずみや間隙水圧を知ることができ,特に,二次圧密を含む時間依存性挙動の考察のためにしばしば採用される.本研究においても,時間依存性挙動を念頭に置き,上記試験機を用いた圧密試験を実施している.圧密試験は,厚さ2cmの試料を3連結して実施している.実験試料としては,カオリンおよび海成粘土を用いている.一般に,間隙水圧の消散と沈下の進行を比較した場合,水圧の消散の方が速くなる傾向がある.この現象を数値解析を用いてを検証した.ついで,二次圧密現象に対して,弾性モデルに粘性項を付加したモデルを利用し,二次圧密に関するパラメータを同定する方法を示した.

DOI： 10.11512/jiban.JGS39.0.205.0

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地すべり解析における有限要素法の利用第9回:2. FEMによる地すべり解析の基礎理論

西村伸一, 堀俊男, 藤井弘章

日本地すべり学会誌 41 ( 2 ) 193 - 197 2004年

Considerations on multidimensional consolidation inverse analysis 査読

S. Nishimura, A. Murakami, Y. Murayama

Inverse Problems in Engineering Mechanics IV 333 - 342 2003年

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：Elsevier Ltd.

This chapter focuses on a multidimensional consolidation inverse analysis. The effects of the measured pore water pressure and the assumption of anisotropy are investigated. An elastoplastic hypothetical ground is analyzed to check the proposed analytical method. The hypothetical observation data are obtained based on the Sekiguchi-Ohtaelasto-plastic model. The effectiveness of the observed pore water pressure is proved
vertical and lateral displacements and pore water pressure are predicted well with the observed pore water pressure. The laboratory anisotropic consolidation tests are also analyzed, because accurate measurements are necessary for the development of the method. The measured deformation and pore pressure obtained in the tests are used for the inverse analysis. According to the results of this analysis
it is shown that the measured pore water pressure and assumption of anisotropy work well, to predict the future consolidation behavior. © 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/B978-008044268-6/50039-9

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浚渫ヘドロ脱水ケーキの変形特性

西村伸一, 井上隆司, 藤井弘章, 脇谷芳招

農業土木学会論文集 226 559 - 560 2003年

練返しおよび不撹乱粘土の鉛直・水平方向圧密係数の比較

西村伸一, 北川佳弘, 西山竜朗, 村上章, 村山八洲雄

農業土木学会論文集 228 ( 6 ) 815 - 822 2003年

練返しおよび不撹乱試料の鉛直・水平方向圧密係数の比較

西村伸一, 北川佳弘, 村山八洲雄, 村上章

地盤工学研究発表会発表講演集 38 277 - 278 2003年

出版者・発行元：公益社団法人地盤工学会

自然堆積地盤には,通常,異方性が存在すると考えられている.本研究は,粘性土地盤の透水性の異方性を考察しようとするものである.ここでは,鉛直排水および放射排水圧密試験を実施し,鉛直方向および水平方向透水係数の比較を行っている.今回は,練返し試料と不撹乱試料を実験に使用し,その比較も行っている.排水方向の違う圧密試験結果を比較する場合,それぞれ一次圧密に要する時間が違うので,実験から求まる圧密定数を比較するのが難しい.そこで,本研究では,二次圧密を考慮した逆解析を実施し,パラメータの同定を行った.結果,提案法によると,鉛直・水平方向の透水係数の相違が鮮明に評価できることが明らかとなった.

DOI： 10.11512/jiban.JGS38.0.277.0

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Consolidation inverse analysis considering spatial variability and non-linearity of soil parameters

S Nishimura, K Shimada, H Fujii

SOILS AND FOUNDATIONS 42 ( 3 ) 45 - 61 2002年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE GEOTECHNICAL SOC

One-dimensional consolidation inverse analysis based on the stochastic nonlinear consolidation model (SNCM) is discussed in this study. The model is determined from the standard consolidation test results, and represents the non-linearity and spatial variability of the coefficient of volume compressibility and the coefficient of permeability simultaneously. Furthermore, the inverse analysis method is proposed on the basis of the SNCM and the finite element method mixed with the Monte Carlo simulation. Measured settlement and pore water pressure are used as observation data in the inverse analysis. The method is applied to the consolidation test results of kaolin clay, and its applicability is confirmed firstly. Then the inverse analysis of an actual soft ground is performed. Future consolidation behavior of the ground is predicted, and the spatial variability and the non-linearity of the consolidation parameters are identified. It is clarified in this study that complicated spatial variability and non-linearity of the consolidation parameters could be considered appropriately in the proposed inverse analysis method, and the method gives accurate prediction of consolidation behavior.

DOI： 10.3208/sandf.42.3_45

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メッシュフリー解法による飽和土の局所化解析

有本慎一, 村上章, 西村伸一

地盤工学研究発表会発表講演集 37 337 - 338 2002年

鉛直方向および水平方向圧密係数の比較

北川佳弘, 西村伸一, 藤井弘章

地盤工学研究発表会発表講演集 37 311 - 312 2002年

双曲線モデルを用いた実測値に基づく軟弱地盤の変形予測

西村伸一, 藤井弘章, 村上章, 松本寛展

地盤工学研究発表会発表講演集 37 965 - 966 2002年

浚渫ヘドロ脱水ケーキの圧縮特性

脇谷芳招, 藤井弘章, 西村伸一, 井上隆司

農業土木学会論文集 214 423 - 430 2001年

間隙水圧の観測結果を利用した粘性土地盤の変形予測

西村伸一, 島田清, 藤井弘章

土と基礎 49 ( 11 ) 10 - 12 2001年

実測値に基づく二次圧密を考慮した圧密沈下予測

西村伸一, 藤井弘章

農業土木学会論文集 216 71 - 79 2001年

逆解析による同定地盤定数の補正法と軟弱地盤の沈下予測

西村伸一, 池内審嗣, 藤井弘章, 島田清

農業土木学会論文集 210 763 - 770 2000年

Damage factors for small embankment dams due to the Hyogoken-Nanbu Earthquake - Case Study on Hokudan Town

藤井弘章, 国政華菜, 難波明代, 横溝隆之, 西村伸一, 島田清, 堀俊男, 西山竜朗

Soils and Foundations 40 ( 6 ) 117 - 131 2000年

記述言語：英語出版者・発行元：地盤工学会

This study was performed to clarify which factors affected damage to tame-ike (small embankment dams for irrigation) in Hokudan Town as a result of the January 17,1995 Hyogoken-Nambu earthquake. Factors were assumed to be : Location (e.g., Distance to Epicenter, etc.), Structure (e.g., Angle to Nearest Fault, Embankment Volume, etc.), Soil Properties of Embankment, Geology of Dam Site and History (Era of Construction, Repaired, etc.). Multivariate statistical analyses were performed for documentary data (damaged : 181,undamaged : 328). Ordinary statistical analyses were conducted for the data investigated in situ for soil properties of the embankment. The results show that the factors causing damage to dam are : (1) Nearest Fault (Nojima, Mizukoshi and D2), (2) Distance to Nearest Fault (less than 500 m), (3) Distance to Epicenter (approximately 8 to 14 km, which almost agrees with the location of seismic intensity 7 JMA), (4) Elevation of Dam Site (higher than 100 m), (5) Embankment Volume (the greater the volume the more damage was caused), (6) Direction of Dam Axis (normal or diagonal to the epicenter or to nearest the fault), (7) Plan View of Dam Axis (3 or 4 axes), (8) Surface Geology of Dam Site (non-cohesive soil type ground), (9) Era of Construction (prior to 1891) and (10) Soil Properties of Embankment (sand, not silty sand or gravel, penetration resistance that is 10% smaller than the undamaged dams).

DOI： 10.3208/sandf.40.6_117

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10423683

Change of shear strength due to surface tension and matric suction of pore water in unsaturated sandy soils 査読

K Shimada, H Fujii, S Nishimura, T Nishiyama, T Morii

UNSATURATED SOILS FOR ASIA 147 - 152 2000年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：A A BALKEMA PUBLISHERS

This paper discusses the change of the normal stress due to the surface tension and the matric suction of the pore water in unsaturated assemblies of spheres, and also discusses the change of the shear strength of sandy soils with the matric suction. Theoretically derived are the relationships between the change of the normal stress and the matric suction in unsaturated assemblies of regularly/randomly packed equal-sized/non equal-sized spheres. Shear tests with poorly- and well-graded sandy soils were also carried out. Experimental results show the same tendency of the relationships between the change of the normal stress and the matric suction as that from theoretical considerations.

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Application of FEM on the basis of elasto-viscoplastic model to landslide problems 査読

H Fujii, S Nishimura, K Shimada, T Hori

SLOPE STABILITY ENGINEERING, VOLS 1 & 2 219 - 224 1999年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：A A BALKEMA PUBLISHERS

This paper discusses the applications of FEM on the basis of the elasto-viscoplastic model to landslide problems. Fluidity parameter gamma which governs the time dependent behavior of landslide, is determined from the comparison of the calculated displacement of landslide with the measured in the Site. Concluding remarks are as follows: 1)The fluidity parameter identified from five typical landslide Sites is within the range of 1*10(-5)similar to 7*10(-4)(day(-1)); 2)The effect of dewatering method was proved by the proposed method; 3)Using this model, it may be possible to make predictions on the future trend of deformation.

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