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饱和软黏土的小应变剪切模量Gmax是其基本力学参数。在进行饱和软黏土的有效应力动力分析时,往往认为小应变剪切模量Gmax只随着有效应力的降低而衰减,而不受动荷载应力历史的影响,因此基本采用静力状态下得到的小应变剪切模量代替相同有效应力时动力状态下的小应变剪切模量。但是,对于饱和软黏土,目前并没有足够多的试验数据证明这一假设。基于这一考虑,通过GDS动三轴及弯曲元测试系统,研究了循环应力历史对饱和软黏土小应变剪切模量的影响,试验结果表明循环应力历史对Gmax的影响较大,采用静力状态下得到的Gmax代替动力状态下的Gmax并不可取。同时,发现可以使用小应变剪切模量的突变来表征饱和软黏土的结构破坏。
The small strain shear modulus Gmax of saturated soft clay is its basic mechanical parameter. In the process of effective stress-dynamic analysis of saturated soft clay, it is often considered that the small strain shear modulus Gmax decays only with the decrease of effective stress and is not influenced by the history of dynamic load stress. Therefore, The small strain shear modulus replaces the small effective shear stress in the dynamic state at the same effective stress. However, there is not enough experimental data to prove this assumption for saturated soft clay. Based on this consideration, the influence of cyclic stress history on the small strain shear modulus of saturated soft clay was studied by GDS moving triaxial and bending element test system. The experimental results show that the history of cyclic stress has greater influence on Gmax, It is not advisable to obtain Gmax instead of Gmax under dynamic conditions. At the same time, it is found that the structural failure of saturated soft clay can be characterized by using the mutation of the small strain shear modulus.