改进复合单元渗透矩阵调整法求解自由面三维渗流场

Improved adjustment method of compound element conductivity matrix for calculating 3D seepage field with free surface

针对现有复合单元渗透矩阵调整法解决无压渗流问题的不足,提出了改进复合单元渗透矩阵调整法。将自由面单元分为干、湿单元以及过渡单元,对于自由面穿越的过渡单元,采用双参数罚函数法,按流量等效将渗流实区渗透系数进行调整,以便更准确地考虑单元的部分饱和和非饱和情况。该方法克服了高斯点附近积分值的不稳定问题,提高了计算精度和收敛速度。同时对有自由面渗流的自由面边界积分问题,提出了一种新的算法。经实例和工程验证,该方法有效可行。

In the light of the inherent drawbacks in the existing adjusting compound element conductivity matrix to calculate unconfined seepage, an improved method of adjusting compound element conductivity matrix is proposed. The free surface elements are divided into the dry elements and the wet elements and the transitional elements, and the penalty function method with double parameters is applied to the transitional elements intersected by free surface. Based on the groundwater flow quantity equivalent effect, the permeability coefficient of the actual seepage field is adjusted so as to precisely consider partial saturation and unsaturation. The unstability integration number near the Gauss point is overcome, and the calculating precision and the convergence speed are improved. Meanwhile, a new method for computing the boundary integration is proposed in free surface seepage field. The method was proven to be effective and feasible by examples and projects.