深厚覆盖层上高土石坝防渗墙裂缝渗流分析模型及应用研究

Research on Crack Seepage Analysis Model of High Earth-rock Dam on Deep Overburden and Its Application

深厚覆盖层上修建混凝土防渗墙在其施工和运行期由于多种原因而容易发生裂缝,可能影响覆盖层地基的渗透稳定性,对工程安全造成难以估量的影响。为有效地求解深厚覆盖层上高土石坝防渗墙裂缝渗流问题,在改进节点虚流量法的基础上引入无厚度的缝单元来模拟防渗墙裂缝渗流行为。以瀑布沟深厚覆盖层工程渗控为例,计算了混凝土防渗墙裂缝未充填和充填下的三维渗流场,得到不同裂缝条件下渗流场的水头分布、浸润线以及渗漏量,系统分析了深厚覆盖层地基中混凝土防渗墙垂直裂缝条件下的稳定渗流场规律和特点。结果表明,该方法能对渗流逸出点和浸润线能准确定位,并能很好地模拟混凝土防渗墙裂缝对坝区渗流场的影响,可以为该类问题的分析提供参考。

The concrete anti-seepage wall built on deep overburden may appear lots of cracks during construction and operating period for various reasons, which would affect the seepage stability of deep overburden and the safety of project. In order to solve the seepage problem of high earth-rock dam on deep overburden with cracks in concrete anti-seepage wall, a crack model with no thickness is introduced based on improved node virtual method. The deep overburden project in Pubugou Hydropower Station is chosen as an example and related three-dimensional seepage field under cracks in concrete wall both un-filled and filled by overburden soil are calculated. The water-head distribution, free surface and seepage under different cracks are obtained. The law and characteristic of steady seepage field of deep overburden with vertical cracks in concrete anti-seepage wall are systematically analyzed. The calculation results show that this crack model can accurately locate seepage escape point and free surface, and can well simulate the influence of cracks in anti-seepage wall to whole seepage field.