利用饱和-非饱和渗流模型计算坝体自由面渗流

Computation of seepage flow of dam′s free surface by using saturated-unsaturated model

建立了一种饱和-非饱和渗流模型求解坝体自由面渗流.该模型将坝体渗流场的饱和区、毛细区、壤水区表述成统一的非线性抛物型方程形式,通过计算近似间断的饱和度函数自动捕获渗流自由面(浸润面).采用空间有限元离散、隐式时间方法求解描述饱和-非饱和渗流场非线性抛物型方程,对复杂坝体自由面渗流的求解精度高、计算方便.利用该方法对辽宁清河发电厂曹家沟灰场灰坝进行了三维数值计算,计算结果与实测及水-电比拟实验结果比较表明,计算结果是可靠的.

A mathematical model is proposed to study the dam′s free surface′s seepage flow by using saturated-unsaturated model. The governing equation can be written as a time-dependant parabolic type, which is fit for all the seepage zones of the saturated region, capillary region and soil water region. Free surface can be automatically captured by computation of saturation function, which is a nearly discontinuous function in thin capillary region. An implicit scheme is used for time step marching of the parabolic type differential equation, with finite element method for space discretization. Numerical experiment for Caojiagou Ash Dam shows that the present method is very convenient and stable for complex seepage flow, and agrees well with the results of the field measurement and electric-hydraulic analogy experiment.