含节理黄土渗流数值模型研究

本文建立了在考虑黄土中有节理存在时,水分场数值计算的有限元方法。采用质量守恒的观点推导了质点元中饱和度的变化与流速的关系。进而利用达西定律得到以水头为变量的渗流基本方程。针对黄土垂直节理的渗流特点,确定了节理渗流基本方程中的参数。采用四边形等参元,利用Galerkin加权余量法建立考虑节理影响的黄土非饱和渗流的有限元形式。对局部水头边界条件下的黄土节理二维水分入渗问题进行了数值分析。结果表明,节理对黄土场地湿润峰的迁移有很大影响。

FINITE ELEMENT SEEPAGE FLOW MODEL FOR UNSATURATED LOESS WITH JOINTS

A finite element method is established for calculating the seepage flow in loess with consideration of its joints' influence. The basic seepage flow equation in unsaturated media is worked out with the view of conservation of mass. It is about the velocity and the saturation's expression. Appling the Darcy law, the variable can be changed from velocity to hydraulic head in the equation. The parameter in the basic flow equation of loess joints is determined according to the characteristic of loess vertical joints. Using the quadrilateral isoparametric element, the finite element form of the equation is given with the Galerkin weighted residual method. Under local Dirichlet boundary condition, the loess 2-D seepage problem is numerically studied considering the influence of loess joint. The results show that joint has a huge influence on the migration of wetting front.