循环作用下粘土应变软化研究

CLAY STRAIN-SOFTENING RESEARCH

循环荷载作用下,饱和软粘土将发生应变软化现象。通过对杭州饱和软黏土进行应力控制的循环三轴试验,研究循环次数、循环应力比、固结比、频率、超固结比对土体应变软化的影响。试验结果表明,循环次数的增加,循环应力比的提高,都将加快土体软化;循环荷载作用下,软黏土存在临界循环应力比,当循环应力比较小或较大时,软化指数与lgN近似为线性关系,而当循环应力比在临界循环应力比左右时,两者表现为明显的曲线关系。

Degradations of stiffness and strength will occur in soft clay under cyclic loading because of the generation of pore pressure.The strain degradation characteristics of saturated soft clay subjected to undrained cyclic triaxial loading is investigated at different cyclic numbers,cyclic stress ratios,consolidation ratios,overconsolidation ratios and frequencies of cyclic loading.It is observed that the degradation index reduces with the progressive cyclic numbers and the increase of cyclic stress ratio.There is a critical cyclic stress ratio in clay subjected to cyclic loading.When the cyclic stress ratio is much higher or lower than the critical cyclic stress ratio,the relationship between degradation index and lg Nis linear.However,when the cyclic stress ratio is around critical cyclic stress ratio,a nonlinear relationship is observed.