复杂应力条件下饱和松砂单调与循环剪切特性的比较研究  

A comparative study on monotonic and cyclic shear behavior of saturated loose sand under complex stress condition

作　　者：栾茂田[1] 许成顺[1] 何杨[1] 郭莹[1] 张振东[1] 

机构地区：[1]大连理工大学海岸和近海工程国家重点实验室

出　　处：《地震工程与工程振动》2006年第1期181-187,共7页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(50179006);国家自然科学基金重点基金项目(50439010);教育部跨世纪优秀人才培养计划研究基金项目;中国科学院武汉岩土力学研究所领域前沿基础研究基金项目(Q110305)

摘　　要：本文利用大连理工大学新引进与开发的“土工静力-动力液压-三轴扭转多功能剪切仪”,针对福建标准砂,在不排水条件下同时进行了单调剪切试验与循环剪切试验,进而对其进行了对比分析。通过比较表明,应力-应变关系的应变软化和硬化特性与流滑变形和循环流动特性密切相关,当循环剪切应力水平高于单调剪切过程中应变软化阶段最小强度时将会发生流滑变形。无论在单调剪切中,还是在循环剪切中,稳定状态时的有效偏应力比随着大主应力方向与竖向之间夹角的增大而减小,在中主应力系数相同的条件下,循环剪切中呈现显著剪胀时的有效偏应力比和最终稳定状态时的有效偏应力比峰值分别与单调剪切中达到相变状态时的有效偏应力比和最终稳定有效偏应力比基本上一致。然而不排水条件下单调与循环剪切过程中孔隙水压力的增长特性却并不相同,循环剪切中的最大孔隙水压力随着初始主应力方向角的增大而减小,单调剪切中的最大孔隙水压力却随着主应力方向角的增大而增大。In this paper, a comparative study on undrained monotonic and cyclic shear behavior of saturated loose sand under complex stress condition is made on the basis of experimental test by using the soil static and dynamic universal triaxial and torsional shear apparatus established in Dalian University of Technology. The different combinations of initial consolidation stress condition and monotonic or cyclic shear stress patterns are considered in the soil tests, h is shown through comparison that the strain-softening or hardening characteristics are closely associated with the deformation features of flow-slide deformation and the cyclic mobility of loose sands. Once the cyclic stress enters the strain-softening region given by monotonic shear loading, the flow-slide deformation will occur. In both monotonic and cyclic shear loading, the effective deviator stress ratio attained at the steady state reduces gradually with the increase of the orientation angle of major principal stress with respect to the vertical direction. Under the condition with the same coefficient of initial intermediate principal stress, the effective deviatoric stress ratio at which a remarkable shear dilation occurs and the effective deviatoric stress ratio peak at which a final steady state is formed in cyclic shear loading are respectively almost same as the effective deviatoric stress ratio at the arrival of phase transformation state and the finally attained steady effective deviatoric stress ratio. However, the behavior of generation and build-up of pore-water pressure is completely different in monotonic and cyclic shear loading. With the increase of the direction angle of initial principal stress, the maximum pore water pressure generated in the cyclic shear reduces gradually while the maximum pore water pressure caused by monotonic shear loading test increases gradually.

关 键 词：单调剪切 循环剪切 复杂应力条件 孔隙水压力 流滑变形 循环流动 

分 类 号：TU141.8[建筑科学—建筑理论] TU411