交通荷载引起主应力轴旋转下软黏土特性试验

Influence of Traffic-loading Induced Principal Stress Rotation on the Characteristics of Soft Clay

为探讨交通荷载引起的主应力轴旋转(即剪应力反转现象)对软黏土动力特性的影响,通过空心圆柱仪(HCA)试验系统,模拟交通荷载作用下土单元的真实应力路径,并对不同轴向偏应力、扭剪应力组合下,软黏土的累积孔隙水压力和累积应变特性进行了试验研究,分析了应力组合模式和幅值对软黏土动力学行为的影响规律。研究表明:施加扭剪应力(模拟主应力轴旋转)会增大软黏土的累积应变和累积孔压,且对孔压的增大影响比对应变更加显著;扭剪应力越大,这种增大效应显著加快,此时在研究交通荷载下软黏土长期变形时,需进行考虑主应力轴旋转的动力试验。

To investigate the effect of traffic-loading induced principal stress rotation（ i.e. shear stress reversal）on the dynamic behaviors of soft clay,through the hollow cylinder apparatus（ HCA） test system,the actual stress path experienced by soil elements under traffic loading was simulated,and the cumulative pore water pressure and cumulative axial strain of soft clay under different combinations of axial deviator stress and torsional shear stress were tested. Based on the testing results,the effects of stress combination mode and stress amplitude on the mechanical behavior of soft clay were investigated. The results shows that the cumulative pore water pressure and cumulative axial strain of soft clay increased when torsional shear stress was applied,and the torsional shear stress had more significant influence on pore water pressure; the higher torsional shear stress,the greater influence on the pore water pressure and cumulative axial strain,and consequently,the dynamic tests including principal stress rotation should be conducted when the long-term settlement of soft clay is studied.