土层非线性动力有限元分析中孔压计算及液化判别

Computation of pore-water pressure and liquefaction predicating for non-linear dynamic finite element analysis of soil

本文基于有效应力路径和损伤指数概念 ,提出了一个能实时计算孔压和分析液化问题的二维有限元程序。本程序考虑了随机地震作用对土的损伤 ,并讨论了损伤指数与振次比的关系。在此基础之上 ,提出了随机地震作用下孔压计算的简化方法。本文提出的孔压增长方程形式简洁 ,变量物理意义明显 ,能够计算任一时刻土体单元的累积孔压。本法具有以下特点 :(1)孔压的实时计算并能反映峰值应力对孔压的影响 ;(2 )考虑了土体的循环软化 ;(3 )孔压和液化判别更为清晰、简洁。

A two-deimension FEM program is presented which can calculates pore-water pressure and predicateds liquefaction of soils based on the concepts of effective and cumulating damage. In program, the damage of soils caused by random earthquake load is considered and the relationship between damage index and ratio of vibration number is discussed. Then, the simplified method for the computation of pore-water pressure at earthquake is presented. Damage index(DI) as the parameter of pore-water pressure equation reflectes the nature, that is, pore-water pressure damages the structure. The method doesn't add any other parameters and is very simple. The features of the program are as follows: (1) calculation of pore-water pressure in real time and reflecting the influence of stress magnitude on pore-water pressure; (2) the cyclic softening of soils is considered; (3) the computation of pore-water pressure and prediction of liquefaction are simple.