基于侧向卸荷的软粘土蠕变试验参数分析

Analysis on creep test regularities of soft clay based on lateral unloading

本文结合K;固结对偏应力水平进行重新定义,通过K;固结室内试验对上海软粘土进行了侧向卸载条件下的分级蠕变试验,以模拟基坑开挖等卸荷条件下土体的工程行为。通过试验发现,Singh-Mitchell方程能很好地拟合软粘土在卸荷条件下的不排水蠕变行为,并通过对试验结果的拟合得到上海软粘土在侧向卸荷条件下的Singh-Mitchell方程参数。与常规加荷试验所得到的参数相比,侧向卸荷条件下的参数m值和α值分别比常规加荷条件下偏小约20%和30%,两者差距主要与试验应力路径和偏应力水平定义不同有关。

In this paper, the deviatoric stress level is redefined based on K;consolidation, and the graded creep tests for Shanghai soft clay under lateral unloading are carried out through K;consolidation laboratory tests to simulate engineering behavior of the soft clay under unloading condition such as excavation. It is found that Singh-Mitchell Equation can well fit the undrained creep behavior of the soft clay under unloading condition, and the parameters of Singh-Mitchell Equation for Shanghai soft clay are obtained by fitting the test results. Compared with the parameters obtained from the conventional loading tests, the values of m and α under lateral unloading are about 20% and 30% smaller than those under conventional loading respectively. The difference is mainly related to the different stress path and definitions of deviator stress level.