自钻式旁压试验中邻近腔壁土的应力路径分析

 采用剑桥自钻式旁压仪对邻近膨胀腔壁土的应力–应变进行研究。根据自钻式旁压试验的特点和腔室膨胀理论，假设试验过程中土只发生小变形，土为弹性–完全塑性材料。基于以上假设，对试验过程的应力路径进行理论推导，并与试验得到的应力路径对比分析，结果表明：两者在弹性阶段差异较大，塑性阶段较为一致；非线性和线性两种理论分析方法相比，前者推导的应力路径理论曲线与试验确定的应力路径更为接近。此外，根据试验确定的应力路径曲线，可以分析土的应力变化，判定土的应力历史，推导土性参数。

ANALYSIS OF STRESS PATHS IN CLAYS ADJACENT TO CAVITY WALL DURING SELF-BORING PRESSUREMETER TESTS

Cambridge self-boring pressuremeter(SBPM) is used in this test to study the stress and strain of the clay adjacent to the expanded cavity wall. Self-boring pressuremeter is a cylindrical device designed to apply uniform pressure to the wall of a borehole by means of a flexible membrane. Both pressure and deformation at the cavity expansion are under the assumptions that the probe is expanded in plain strain，undrained，axially symmetric about the pressuremeter and in elastic-perfectly plastic material. Based on the hypothesis，theoretical stress path is deduced；and comparison between the theoretical stress path and experimental one has been made. The results show that in the plastic phase，the theoretical stress path corresponds well with the experimental one，while in the elastic phase，the correspondence is less satisfactory. Comparison between the theoretical curves deduced by nonlinear and linear analysis with the experimental ones indicates that nonlinear analysis fits well with the actual behaviour of clay. Besides，according to the curve of stress path，variety of stress in the clay is analyzed；stress history of the clay is determined；and some parameters of the clay are deduced.