交通荷载作用下饱和软粘土孔压-应变分析模型

针对交通荷载的作用特点设计了循环三轴试验,进而对交通荷载作用下饱和软粘土的动力特件进行厂研究.结果表明:循环荷载作用下,饱和软粘土存在临界循环应力比,采用孔压曲线所得到的临界循环应力比要小于采用应变曲线所得到的临界循环应力比.当土样不存在初始剪应力时,随着循环次数的增加,土样的应力-应变关系曲线近似原点对称,但随着初始剪应力的增大,应力-应变关系曲线逐渐表现为一系列平行曲线,峰值孔压与循环孔压幅值均逐渐减少;同时,轴应变的发展加快,但循环应变幅值逐渐减小.当循环应力比小于临界循环应力比时,对于同一初始剪应力,不同循环应力比下的孔压比-动应变曲线近似集中在同一条曲线上.通过对试验数据进行回归分析,得到了交通荷载作用下饱和软粘土残余孔压-累积塑性应变关系模型.

Pore water pressure-residual strain model of soft clay under traffic loading

According to characters of traffic loading,cyclic triaxial tests were designed to study the dynamic behavior of saturated soft clay under traffic loading.Results show that there is critical cyclic stress ratio of soft clay under cyclic loading.The value of critical cyclic stress ratio obtained by pore water pressure curves is lower than that obrained by dynamic strain curves.The stress-strain curves is approximately symmetrical around origin when there is no initial shear stress.At a higher initial shear stress,the stress-strain curves are nearly parallel to each other with the progressive number of cycles.With the increase of initial shear stress,peak pore water pressure and cyclic pore water pressure amplitude decrease.The axial strain increases significantly,and the cyclic strain amplitude decreases as the increase of initial shear stress.When the cyclic stress ratio iS lower than the critical cyclic stress rati-o,the pore water pressure ratio and dynamic strain data are concentrated on one curve for the same initial shear stress.The residual pore water pressure-accumulative plastic strain model of soft clay under traffic loading is obmined by regression.