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991.
This paper addresses various issues concerning the modelling of solid–liquid–air coupling in multiphase porous media with an application to unsaturated soils. General considerations based on thermodynamics permit the derivation and discussion of the general form of field equations; two cases are considered: a three phase porous material with solid, liquid and gas, and a two phase porous material with solid, liquid and empty space. Emphasis is placed on the presentation of differences in the formulation and on the role of the gas phase. The finite element method is used for the discrete approximation of the partial differential equations governing the problem. The two formulations are then analysed with respect to a documented drainage experiment carried out by the authors. The merits and shortcomings of the two approaches are shown. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
992.
Development of shear bands in saturated soils is a multi-stage process based on the theoretical and numerical investigations in this paper. The soil is initially in homogenous shear strain state, and the instability can be characterized by a dimensionless number D. The inhomogenous distribution of shear strains appears when D>1, and the shear band will initiate and develop gradually. Numerical solutions show that only single shear band that is finally formed in the central region of the specimen even several disturbances (distributed along the specimen) appear in the beginning. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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994.
Shear induced collapse settlement of arid soils 总被引:1,自引:0,他引:1
H. A. Alawaji 《Geotechnical and Geological Engineering》2001,19(1):1-19
This paper presents the results of studies of deformation, strength and collapsibility of loess soils. Samples were taken from Al Dalam in central Saudi Arabia, which resembles an arid region. These samples were subjected to various laboratory tests to determine their physical and engineering properties. Sets of oedometer and direct shear tests were carried out in which the initial dry density and the normal pressure at wetting and shearing were each varied in turn. Oedometer results indicate that collapse potential decreases with density and increases logarithmically with normal pressure. Shear induces further collapse potential which increase with density due to further destruction of soil fabric. A unique shear stress–shear strain relationship was obtained for specimens prepared at different initial fabrics. Dry and soaked failure envelopes were both non-linear in the low-pressure range. Wetting induced a reduction in the shear strength parameters. The results of the tests are reported, and the significance of each variable is assessed. 相似文献
995.
大同--运城高速公路某软基复合地基检测结果分析 总被引:2,自引:2,他引:0
毛新虎 《地球科学与环境学报》2004,26(1):33-37
以山西大运高速公路某段软基处理为例,从挤密碎石桩的加固机理和破坏方式入手,通过对软基复合地基的原位测试结果分析,得出碎石桩不但提高了地基的承载力,增加了桩间土的强度,减少了地基沉降,而且消除或减轻了地基的液化,使复合地基承载力达到了设计要求,特别是为以后在高速公路修筑中的软基处理提供了参考资料. 相似文献
996.
LIFang LIUZhi-ming 《中国地理科学(英文版)》2004,14(1):57-62
By establishing the interpreting elements, and applying supervised classification, the sandy desertification was interpreted and the desertified land areas of the counties in the western Jilin Province in 1986 and in 2000 were obtained. Taking Tongyu and Qian‘an as examples, the natural driving forces and man-made driving forces were analyzed. The paper comes the conclusions that the material sources and the warming and dry climate are the internal causes of potential land descrtification: the irrational human activities, such as destroying forest and reclaiming the grassland, are the external causes of potential land desertification; while more rational human activities, such as planting trees and restoring grassland can reverse the land desertification. Furthermore, the countermeasures and suggestions for the development of agriculture and animal husbandry in the western Jilin Province are put forward. 相似文献
997.
Lin Li 《中国地质大学学报(英文版)》2011,(5)
Partial least squares(PLS) regression was applied to the Lunar Soil Characterization Consortium(LSCC) dataset for spectral estimation of TiO2.The LSCC dataset was split into a number of subsets including the low-Ti,high-Ti,total mare soils,total highland,Apollo 16,and Apollo 14 soils to investigate the effects of interfering minerals and nonlinearity on the PLS performance.The PLS weight loading vectors were analyzed through stepwise multiple regression analysis(SMRA) to identify mineral species driving and... 相似文献
998.
999.
1000.
研究了横观各向同性饱和土地基在地表动力荷载作用下的三维瞬态响应。基于饱和多孔介质的三维Biot波动理论,利用Laplace变换,建立圆柱坐标系下横观各向同性饱和土的波动方程;解耦波动方程后,根据算子理论,并借助Fourier展开和Hankel变换技术,得到瞬态荷载作用下,饱和土介质的土骨架位移和应力、孔隙水相对位移和孔隙水压力的一般解;利用一般解,给出横观各向同性饱和地基在地表集中荷载激励下的瞬态Lamb问题的解答。数值算例结果表明,采用各向同性饱和介质的动力学模型,不能准确描述具有明显各向异性特性的饱和土地基的瞬态动力特性。 相似文献