关键词: 坝基, 防渗墙, 二维稳态渗流, 渗透各向异性, 显式解析解, 扬压力, 渗流量, 出口梯度

Abstract: Since two or more anti-seepage walls are usually required in the present design of dam foundation, the anisotropic steady-state seepage of dam foundation with anti-seepage walls at both ends is analytically studied in this paper. The soil is divided into four regular regions, the anisotropic soil layer is converted into the equivalent isotropic soil layer by coordinate transformation, and the water head distribution in the four regions is expressed as a series solution by using the separation variable method. The explicit analytical solution of the anisotropic seepage field of the dam foundation with anti-seepage walls at both ends is obtained by combining the continuity conditions between regions. The analytical solution in this paper is reduced to the seepage flow under isotropic conditions, the uplift pressure at the dam bottom, the analytical solution and numerical results of conformal transformation are compared. The head value under anisotropic conditions is compared with the calculation results of the finite element software. The results are in good agreement, which verifies the correctness of the analytical solution in this paper, and the analytic solution has a higher accuracy than the analytical solution of conformal transformation. Finally, a parametric analysis of the seepage field at the base of the dam shows that soil anisotropy has a non-negligible effect on seepage at the base of the dam, and that, all other things being equal, the seepage volume and outlet hydraulic gradient of a soil with a larger ratio of vertical to horizontal permeability coefficient will be smaller than those of a soil with a smaller ratio of vertical to horizontal permeability coefficient; the maximum lift pressure of a soil with a larger ratio of vertical to horizontal permeability coefficient will be larger than that of a soil with a smaller ratio of vertical to horizontal permeability coefficient.

Key words: dam base, anti-seepage wall, two-dimensional steady seepage, permeability anisotropy, explicit analytical solution, uplift pressure, seepage flow, outlet hydraulic gradient