基于坝—岩基—水耦合解析的坝肩动力稳定分析

为了模拟三维状态下坝、岩基、库水的动力相互作用机理,研究提出了基于坝—岩基—水耦合的三维有限元分析方法。通过分析坝—岩基—水耦合动力相互作用理论,给出了坝—库水体的耦合条件、坝—岩基—库水的边界条件以及地震时粘性边界的分析方法。以某拱坝工程为实例,应用耦合三维有限元方法计算了拱坝及滑裂面应力分布,采用有限单元法和刚体极限平衡法,计算了坝肩各处的抗滑稳定安全系数。结果表明:最大拱向应力、梁向应力均出现在下游面,分别为1.43 MPa、1.50 MPa,在材料可承受的范围内。通过有限元法计算得到的拱坝坝肩岩体抗滑稳定安全系数为2.78~3.23,通过刚体极限平衡法计算的抗滑稳定安全系数为2.89~3.43,两者相差很小,说明该计算方法是有效的。研究成果可为拱坝坝肩抗滑稳定分析提供参考。

Dam rock foundation water coupling analysis based study on abutment dynamic stability analysis

In order to study the dynamic interaction mechanism among dam，rock foundation and reservoir water under the simulated 3-D status，a dam，rock foundation and reservoir water coupling based 3-D finite element analysis method is studied and proposed herein. Through the analysis on the theory of the dynamic interaction coupling among the dam，the rock foundation and reservoir water，the coupling condition for dam reservoir water，the dam rock foundation water boundary condition and the analysis for the viscous boundary under the condition of earthquake are given out. By taking the construction of an arch dam as the study case，the stress distributions of the arch dam and the slip fracture plane are calculated with the coupling 3-D finite element method，and then the anti slide safety factors all over the abutment are calculated with the finite element method and the rigid limit equilibrium method. The result shows that both the maximum arch stress and the hoop stress occur at the downstream face and are 1.43 MPa and 1.50 MPa respectively，and then both are within the affordable range of the materials. The anti slide safety factor of the rock mass at the abutment of the arch dam obtained through the finite element calculation is 2.78～3.23，while the anti slide safety factor calculated through the rigid limit equilibrium method is 2.89～3.43. Thus，the difference between both of them is very small and it is indicated that the calculation method is effective. The study result can provide a reference for the anti sliding stability analysis on the abutment of arch dam.