应变软化土体扩孔问题的大变形解析  

Large-deformation Analysis for Cavity Expansion in Strain-softening Soil

作　　者：邹金锋[1,2] 罗恒[1] 彭建国[2] 安爱军[1] 张进华[2] 

机构地区：[1]中南大学土木建筑学院,湖南长沙410075 [2]湖南省交通规划勘察设计院,湖南长沙410008

出　　处：《中国公路学报》2009年第4期20-27,共8页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(50408020);铁道部科技重点项目(2008G032-3)

摘　　要：将圆孔周围土体变形区分为弹性区、软化区和流动区,在弹性区中采用小变形理论,在软化区和流动区中采用大变形理论和非相关联流动准则,假定土体服从统一强度准则,根据应力平衡方程、应力和应变连续的边界条件,推导出考虑土体剪胀和中主应力等影响因素的应力和应变场分布规律、区域半径和极限扩孔压力的理论解答;并将极限扩孔压力理论的计算结果与传统Vesic扩孔理论计算结果进行对比。结果表明:扩孔压力和软化区半径受土体剪胀的影响比受参数b的影响大,而且球孔比柱孔更加显著;极限扩孔压力理论计算结果与Vesic结果非常接近。The strain distribution due to the cavity expansion in soil was considered as three regions, namely elastic region, softening region and flowing region. Little deformation theory was used in elastic region. Large-deformation nonassociation flow rule was used in softening region and flowing region. Unified strength criterions were taken into consideration in soil deformation. According to stress equilibrium equation and continuous boundary condition of stress and strain, considering influence of soil dilation and middle major stress, the rule of stress and strain distribution field in three zones, the region radius and limited cavity expansion pressure were obtained. The results calculated by limited cavity expansion pressure and traditional Vesic cavity expansion theory respectively were compared. Results show that the influence of soil dilation on cavity expansion pressure and the radius of softening region is stronger than the influence of b on those, and the influence of expansion pressure of spherical cavity is stronger than that of cylindrical cavity. The result calculated by limited cavity expansion pressure is very near to that calculated by Vesic cavity expansion theory.

关 键 词：道路工程 应变软化土体 理论分析 大变形 剪胀 中主应力 扩孔半径 

分 类 号：U416.1[交通运输工程—道路与铁道工程]