分阶段循环加载条件下温州饱和软黏土孔压和应变发展规律

Pore pressure and strain development of Wenzhou saturated soft soil under cyclic loading by stages

土体在经过一定次数的循环荷载作用后,其动力特性会发生改变,对后续振动的响应会变得大不相同。通过对温州原状饱和软黏土分别在不排水和排水条件下进行连续循环加载和5个阶段的分阶段循环加载试验,分析了循环荷载作用及一定时间的停振对土体动力特性的影响。试验结果表明,一定时间的振动和停振后,由于土体动力特性发生了改变,后续阶段的残余应变将变小;不排水条件下,停振期孔压稳定在循环加载产生的残余孔压值附近,而振动期产生的变形一部分得到恢复;排水条件下,在振动期孔压呈现出先增大后减小的趋势,在停振期残余应变基本保持不变。这些结论对于深入分析交通荷载下土体动力响应和沉降发展具有一定的指导意义。

After a certain number of traffic loads, soil dynamic characteristics are changed, which makes the response of the next cyclic loading different. Through the successive cyclic loading and 5-stage loading tests on Wenzhou saturated soft soil under undrained and drained conditions separately, the effects of post-cyclic loading with no vibration for a certain time on the soil dynamic characteristics are analyzed. The experimental results show that after a certain time of cyclic loading with no vibration, the cumulative strain is reduced because of the change of soil dynamic behaviors; under undrained conditions, the pore pressure is stable at the value of cumulative pore pressure generated by cyclic loading and part of strain generated by cyclic loading resumes; under drained conditions, the pore pressure firstly increases and then decreases at the stage of cyclic loading while the cumulative strain keeps mostly unchangeable. The conclusions should be helpful for in-depth analysis of the dynamic response and settlement development of soil under traffic loading.