基于固液两相耦合物质点法的饱和地基液化数值计算方法

Numerical calculation method of saturated ground liquefaction based on solid-liquid two-phase coupling material point method

为研究动力荷载作用下饱和地基液化问题,编制了可用于分析固液两相介质相互作用的三维显式物质点法程序MapleLeaf。首先,基于多孔介质理论,采用单点格式同时描述固液两相介质,推导u-p格式下固液两相耦合物质点算式;然后,通过静水压力柱三维模型及太沙基一维固结理论模型的数值解与理论解的对比分析,验证程序在固液两相静力条件下物质点法数值计算的可靠性;接着,增加动力算法模块,引入可用于分析动力条件下饱和土体液化问题的Cyclic Mobility本构模型;最后,分别基于现有文献及现场制备的振动台饱和地基模型,建立物质点数值模型,通过物质点法模型数值解与试验结果的对比分析,验证程序在动力条件下饱和地基液化问题分析的准确性。结果表明:基于物质点法的固液两相耦合数值计算方法能够较好反应动力条件下饱和地基液化前后超孔隙水压值的增长和消散的基本规律。编制的物质点法程序能够准确分析动力荷载作用下饱和地基液化问题。

In order to study the liquefaction of saturated foundation under dynamic conditions,a three-dimensional explicit material point method program MapleLeaf is developed by the interaction for the solid-liquid two-phase medium in this paper.Firstly,based on porous media theory,a single-point scheme is used to describe the solid-liquid two-phase medium.The formula of solid-liquid two-phase in the u-p scheme is derived.Secondly,the reliability of the numerical calculation under the solid-liquid two-phase static condition is verified by comparing the numerical results of the three-dimensional model of hydrostatic pressure column and the theoretical model of Terzaghi′s one-dimensional consolidation.Then,a dynamic algorithm module is added.And the Cyclic Mobility constitutive model for analyzing dynamic liquefaction is introduced into the program.Finally,based on saturated foundation model prepared from the existing literature and the shaking table system in the field,the three-dimensional numerical model is established.By comparing the numerical solution of the material point numerical model with the experimental results,the accuracy of the program in analyzing the liquefaction problem of saturated foundations under dynamic conditions is verified.The results show that the solid-liquid two-phase coupling numerical calculation method based on the material point method can better reflect the basic law of the growth and dissipation of excess pore water pressure before and after liquefaction of saturated foundation under dynamic conditions.The material point method program developed in this paper can accurately analyze the liquefaction of saturated foundation under dynamic conditions.