接触面单元计算土石坝渗流逸出点的效果分析

为研究利用接触面单元方法计算渗流逸出点的处理技巧及其效果,针对2个渗流算例进行计算,其中对浸润线穿越的单元用蒙特卡罗积分方法计算其复合渗透系数。在渗透系数相差较大的材料之间设置2层接触面单元,利用接触面的渗流矩阵建立材料间的水力联系,通过迭代得到浸润线位置。选择较薄的接触面单元厚度(比如相邻单元厚度的1/4),把计算误差控制在局部范围内,而对整体没有太大影响。分析结果表明,选择合适的接触面渗透系数或透水率,能够得到接近于常规方法的计算结果。

Effect of interface elements on calculating the release point of earth-rock dam

In the calculation of seepage or consolidation, if there is a large difference in seepage coefficient of two adjacent materials, the release point, as well as the phreatic line, should be determined by iterations. However, if we set interface elements between two materials, reasonable results of release point can be captured without iterations. In this paper, two seepage cases are investigated, and the composite seepage coefficient of the elements, which are intersected by the phreatic line, is calculated with the Monte Carlo integration method. Two interface elements are set between two materials with great difference in seepage coefficient. The hydraulic relationship between two materials is built based on the seepage matrices of the interface elements, while the location of the phreatic line is then calculated by iterations. Choosing a thin thickness for the interface element(e. g. , 1/4 of the thickness of the adjacent element)could localize the error of calculation, which has little impact to the whole area at the same time. By choosing an appropriate seepage coefficient or permeability rate of the interface element, results close to those obtained through the traditional methods can be acquired, which shows the applicability of the proposed method.