复杂应力路径下影响黏土孔压开展的因素研究  

Influencing factors about pore pressure generated for clay under complex stress path

作　　者：温晓贵[1] 张勋[1] 周建[1] 

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,浙江杭州310058

出　　处：《岩土工程学报》2010年第11期1709-1716,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(50778162);"十一五"国家科技支撑计划项目(2008BAJ06B01-4);浙江省留学回国基金项目(J20090026)

摘　　要：采用空心圆柱扭剪仪,针对杭州原状软黏土,设计轴对称和三维应力状态下的复杂应力路径,进行固结不排水条件下的主应力轴旋转试验,以此从试验上验证主应力轴转幅、中主应力系数、初始剪应力对剪切过程中孔压开展特征影响的理论分析结论。理论分析和试验结果均表明:在主应力轴旋转过程中,主应力轴转幅分别为0°～45°和45°～90°间的值时,试样的变形不同,产生的孔压增量不同,以主应力轴转幅等于45°为界;当中主应力系数在0～1间变化时,随着中主应力系数的增大,产生的孔压增量先减小后增大,以中主应力系数等于0.5为界,并且,中主应力系数对剪切过程中孔压开展的影响受剪应力水平的控制;初始剪应力水平越高,上升初始剪应力阶段产生的孔压增量越大,剪切过程中总的孔压水平越高。在包含主应力轴旋转和剪应力增大的剪切应力路径初始阶段,以大主应力方向角作为控制条件比以初始剪应力作为控制条件产生的孔压增量大,对剪切过程中孔压的开展影响更大。A hollow cylinder apparatus is used to carry out tests on the principal stress axis rotation for Hangzhou intact soft clay under consolidated undrained conditions,and complex stress path under axisymmetric and three-dimensional stress state is designed.The theoretical results about the impact of rotation rate of the principal stress axis,coefficient of the intermediate principal stress and the initial shear stress on the pore pressure characteristic is validated in tests.The theoretical analyses and test results reveal that the deformation of specimens and the increment of pore pressure generated in the rotation rate of the principal stress axis between 0 and 45 degrees are different from those in the rotation rate of the principal stress axis between 45 and 90 degrees during the rotation of the principal stress axis,and the rotation rate of 45 degrees is the cut-off point.When the coefficient of the intermediate principal stress changes between 0 and 1,the increment of the pore pressure generated decreases first and then increases with the increase of the coefficient of the intermediate principal stress,and the coefficient of 0.5 is the cut-off point,and the impact of the coefficient of the intermediate principal stress on the pore pressure generated is controlled by the level of shear stress in the shearing process.The higher the initial shear stress,the greater the increment of the pore pressure generated in the increasing stage of the initial shear stress and the higher the overall level of the pore pressure in the shearing process.The angle of the major principal stress direction as the control conditions will generate more increment of pore pressure than the initial shear stress as the control conditions in the initial stage of shear stress path including the rotation of the principal stress axis and the increase of the shear stress,and it has a greater impact on the pore pressure generated in the shearing process.

关 键 词：空心圆柱扭剪仪 孔压 主应力轴转幅 中主应力系数 初始剪应力 

分 类 号：TU411[建筑科学—岩土工程]