Three-dimensional Aseismic Stability Analysis Of High Concrete Face Rockfill Dam Based On Finite Element Sliding-surface Stress Method

As more and more high earth-rock dams in China are planned and constructed in areas with complex geological conditions and frequent seismic activities in the Midwest,the aseismic stability design and safety evaluation of high earth-rock dams have received more attention.Especially for 300 m grade super high dams,the previous two-dimensional and pseudo-static stability analysis methods can no longer meet the actual engineering evaluation requirements.Therefore,it is of great significance to study the three-dimensional dynamic stability of high earth-rock dams.In this paper,based on the finite element sliding surface stress method,the twodimensional finite element dynamic stability analysis thought is extended to three-dimensional.From the theory of limit equilibrium method and the realization of the finite element method,the safety factor and slip amount are comprehensively considered as the evaluation criteria.The stability characteristics of high concrete face rockfill dams under continuous earthquake are studied in detail,and a three-dimensional aseismic stability evaluation method for high earthrock dams is preliminarily established.The main work of this paper is as follows:(1)The main methods for slope stability in recent years have been compared and analyzed.Although traditional limit equilibrium method has many advantages and engineering experience,it is not suitable for high earth-rock dam projects that can be efficiently calculated on a large scale.The finite element strength reduction method is suitable for the complicated slope calculation of soil materials,but it is difficult to realize the whole continuous dynamic calculation due to the complexity of the evaluation criteria.Finite element sliding surface stress method can be better combined with mature three-dimensional nonlinear dynamic analysis,and has a high engineering reference value.(2)Based on the finite element sliding surface stress method and the block rotationsliding method,a three-dimensional earth-rock dam aseismic stability analysis program is compiled using C++ programming language.The reliability and accuracy of the program are verified by comparison of examples.(3)In view of the three-dimensional characteristics of high face rockfill dams,the effects of dam height,bank slope and valley width on the dynamic stability of the downstream slope are compared and analyzed.The results show that the increase in dam height result in a decrease in the minimum safety factor.The asymmetry of the bank slope makes the most dangerous sliding move towards to the side of the gentle slope.The narrow valley has great fluctuation on the stability,and the valley tends to be stable when it is very wide.(4)The above method is applied to the dynamic stability analysis of "Houziyan Face Rockfill Dam".The three-dimensional stability of the downstream slope is analyzed from the aspects of dynamic response,safety factor time-course,slip amount,and location of the slip surface.Meanwhile,the reinforcement range advice is given.