考虑砂土内在各向异性的地基承载能力的动力分析与研究

项目名称： 考虑砂土内在各向异性的地基承载能力的动力分析与研究

项目编号： No.51278307

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 建筑科学

项目作者： 明海燕

作者单位： 深圳大学

项目金额： 80万元

中文摘要： 砂土在不排水三轴拉伸条件下的临界状态强度远低于在三轴压缩条件下的临界状态强度。除受剪切模式的显著影响，砂土的不排水剪切特性特别是趋近于临界状态破坏的应力路径，还明显地受主应力方向的影响。宏观力学实验和微观结构分析都将砂土在不同加载条件下强度的显著差异归因于土骨架结构的各向异性。在地震作用下砂土地基承载能力与地基土的临界状态强度密切相关。在研究地基承载能力时考虑砂土内在各向异性的影响，对理解地震作用下砂土地基承载能力的变化具有重要意义。在一个场地的主动和被动破坏区中，主应力方向的变化非常显著，不同区域的相同土的不排水临界状态强度差别显著。本项目结合材料实验、计算机数值分析和离心机物理模拟等方法，研究在不同沉积条件下沉积的砂土地基在地震作用下变形和破坏的机理，研究砂土内在各向异性对地基抗震性能的影响，揭示在地震作用下地基承载能力的变化与土的基本性之间的关系。

中文关键词： 离心机模拟；地基承载力；各向异性；液化；地震响应

英文摘要： Recent laboratory investigations indicate that the stress-strain-strength responses of granular soils are appreciably affected by the fabric orientation of the soil relative to the frame of principal stresses. Especially, a sand specimen exhibiting a dilative response during triaxial compression may show a contractive response during triaxial extension under otherwise identical conditions. The results of experimental and microstructural investigations attribute the significant difference in strength under various loading conditions to inherently anisotropy of soil skeleton, i.e., fabric anisotropy. This observation is of practical importance for applications concerning essentially undrained loading conditions, because the effective mean normal stress at failure, and consequently, the shear strength, associated with an undrained contractive path are considerably lower than those following a dilative path. Subjected to earthquake loading, the bearing capacity of a sand ground is closely related to the undrained critical state strength of the soil. It is important to consider the influence of fabric anisotropy of the soil on seismic performance of the ground in order to understand the evolution of its bearing capacity during earthquake shaking. For a ground, the variation of the direction of principal stress in the

英文关键词： Centrifuge modelling；Bearing capacity；Fabric anisotropy；Liquefaction；Seismic response