渗透压力对重力坝有限元分析的影响研究

Research on action of seepage pressure on gravity dam in FEM

针对有限元分析重力坝的应力和抗滑稳定性时,如何正确模拟作用在建基面上的扬压力的问题,通过对有限元法中不同扬压力施加方式对计算结果影响的分析比较,探讨了各自的适用性。采用平面渗流理论,分析了渗透压力对坝体变形、应力分布及抗滑稳定的影响。数值计算结果表明:坝体内渗流场形成后,将扬压力以面力的形式施加在建基面上的方法是不可取的;采用浮重度的方式模拟扬压力的作用,得出结果的可以近似地满足工程精度要求。计算结果还表明,防渗帷幕和排水孔对重力坝的应力、抗滑稳定具有较大的影响。

Aiming at how to simulate the uplift pressure of the interface between dam and foundation in the stress and stability analysis of dam with finite element method(FEM),different numerical simulation methods of imposing uplift pressure are analyzed. By comparing the influence on the deformation,stress distribution and stability of dam foundation rock,their applied range and limitation are indicated respectively for specific application purpose. At the same time,the influence of dam seepage fields on the dam deformation is discussed based on spatial seepage flow theory. The research shows that irrational results might be obtained when uplift pressure is used to act on one side of element of the interface between dam and foundation as face loads,and the numerical result calculated by using the buoyancy unit weight of concrete under the saturated surface can agree well with that calculated by the seepage-body-force. The research also indicates that the curtain and drainage hole have a considerable influence on the stress distribution and stability of concrete gravity dam.