土体液化动力分析数值模型

基于有效应力原理,采用满足Masing准则的修正双曲线模型描述土的本构关系,建立了一种土体液化动力分析的数值模型,该模型反映出地震引起孔压增长及伴随的土体软化效应且特别考虑了围压对场地液化的影响.孔压增长模型选用Ishibashi和Sherif等提出的等效循环孔压模式.为了验证模型在模拟地震触发场地液化分析的可靠性,直接针对自由液化场地振动台试验,建立了自由液化场地地震反应的二维分析模型和计算方法;土箱-地基边界采用并联弹簧-阻尼器模拟,体系的动力方程采用Wilson-θ逐步积分法求解.通过试验值与计算值的对比分析,评估了数值建模途径和计算方法的可靠性;总体来看,试验结果与计算结果吻合较好,一定程度上验证了模型良好的模拟能力和正确性,可有效地用于场地液化动力分析.

Numerical model for dynamic analysis of soil liquefaction

This paper presents an effective stress-based numerical model for dynamic analysis of soil liquefaction considering the effect of confining pressure on of dynamic properties soil,which can be used to describe the pore pressure increment and the consequent loss of soil strength due to earthquake-induced shaking.The emendatory hyperbolic model which meets Masing rule is adopted for nonlinear analysis of soils in numerical model.The pore pressure generation is calculated using the equivalent cycle pore pressure model developed by Ishibashi and Sherif et al.To demonstrate the relability of the new method for dynamic soil liquefaction analysis,a two-dimensional numerical model is directly established to simulate shaking table test for seismic response of liquefiable ground,the parallel spring-damper connection is used to simulate the artificial boundary of computational domain and the Wilson-θ integral method is selected to solve dynamic equations of seismic response.The results obtained from the new analysis agree well with recorded accelerations and pore pressure ratio in the shaking table test,which shows the reliability and validity of the numerical model.