饱和软黏土动力学特性循环扭剪试验研究

Cyclic torsional shear experimental studies on dynamic characters for saturated soft clay

以饱和软黏土的循环扭剪试验研究为基础,阐明不固结不排水条件下饱和软黏土的动力学特性。在循环扭剪和循环三轴两种不同试验应力状态下,通过研究不同围压和不同静、动应力组合下饱和软黏土的应力等效破坏关系和应变等效破坏关系,提出在循环荷载作用下饱和软黏土的循环破坏同样遵循Mises屈服准则,且在Mises屈服准则下,饱和软黏土的循环强度趋于不变量。循环破坏的过程可以等效为一种拟静力弹塑性循环蠕变,建立了饱和软黏土循环累积变形随静荷载、循环荷载以及循环破坏振次之间的关系式。上述结论分别从应力和变形两个方面阐述饱和软黏土的动力学特性,与试验应力状态和围压无关,可以推广到一般应力状态下。

Dynamic characters of saturated soft clay strata have been studied under unconsolidated undrained condition based on the cyclic torsional shear test results. Stress equivalent failure relationship and strain equivalent failure relationship have been studied under different confining pressures and different stress combinations through cyclic torsional shear tests and cyclic triaxial tests. Analyzing the tests results of different test stress states, it is surprising finding that saturated soft clay followed Mises criterion under static combined cyclic loads as same as under static loads. And the cyclic strength is an invariable on certain static loads and certain number of circles to failure. Further, the pseudo-static elastoplastic cyclic creep relation, that is, the changing law of cyclic accumulate strain with static loads and cyclic loads as well as number of circles to failure is built through cyclic triaxial tests results. And this relation is in harmony with cyclic torsional shear test results. Then we can draw a conclusion that cyclic stress followed Mises criterion and cyclic failure course met pseudo-static elastoplastic cyclic creep for saturated soft clay under unconsolidated undrained condition. These conclusions not related to the testing stress states and confining pressures, it can be popularized in general stress states. It is the basis for research cyclic failure mechanism of saturated soft clay.