前坪水库大坝坝体及坝基渗透稳定研究

Study on Seepage Stability for Dam and Dam Foundation of Qianping Reservoir

前坪水库大坝为黏土心墙砂卵砾石坝,属高坝,心墙土料与坝壳砂卵砾石料、堆石料渗透系数差别较大,坝基存在深厚透水性较强覆盖层,因此研究其坝体、坝基渗透稳定性,分析易发生渗透破坏的部位及其特性十分必要。通过建立渗流场水文地质模型,采用二维数值模拟和三维有限元两种分析方法分别进行了坝体、坝基平面和立体有限元渗流分析,通过定性分析与定量计算进行了坝体、坝基渗透稳定性评价和渗流量估算。计算结果表明:心墙出逸点处、防渗墙伸入心墙部分容易出现渗透破坏,均需采取相应保护措施;三维有限元计算是对二维数值计算的扩展和延伸,对于高坝、边界条件复杂的大坝,更能模拟其实际渗流特性,以便有针对性地提出防治措施。

The high dam of Qianping Reservoir belongs to clay core wall sand gravel dam. The permeability coefficient of core wall soil isquite different from shell sandy gravel and rockfill. Since there is strong water-permeable covering layer in the foundation, it is very necessaryto study the seepage stability of dam and dam foundation and analyze the location and characteristics of seepage damage. In this paper, themethods of two-dimensional numerical simulation and three-dimensional finite element were used to analyze the seepage of dam, foundationplane and three-dimensional finite element by establishing the hydrogeological model of seepage field. The results show that the seepage dam-age is easy to occur at the outlet point of the core wall and the impervious wall penetrated into the core wall. Thus, corresponding protectivemeasures should be taken into consideration for these areas. In addition, as an extension for two-dimensional numerical calculation, three-di-mensional finite element method is better at simulating the actual seepage characteristics for high dams and dams with complex boundary con-ditions, which can help to put forward corresponding prevention measures.