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沙牌RCC拱坝是少数经受了大地震考验的百米级高坝实例之一,其动力稳定性再研究意义重大。为研究其经受同等或更高强度地震作用下的坝肩动力稳定性,综合有限元法与刚体极限平衡法的优势,提出一套基于多重网格法的有限元刚体极限平衡法(FEM_LEM)的坝肩稳定分析方法,同时提出极限累积位移公式作为滑块失稳判据,开展了2种地震波作用下的沙牌坝肩动力稳定分析,并对“5·12”地震反演的人工波开展了拱坝坝肩稳定性超载分析。结果表明:在反映“5·12”地震的人工波(ah=2.05 m/s2)作用下,沙牌左右坝肩稳定,与实际地震效应一致。在设计波(ah=5.31 m/s2)作用下,沙牌左岸坝肩将失稳,而右岸仍稳定。进行人工波超载分析时,左岸坝肩滑块L1、L2分别经受3.2、3.6倍人工超载波时会发生滑移失稳;右岸坝肩滑块则在4.2倍超载波作用下滑移失稳。此次沙牌坝肩动力稳定再分析考虑了滑块滑移方向及安全系数瞬态变化对滑块累积位移的影响,更真实地反映了沙牌拱坝坝肩滑块滑移规律,为工程实际中的坝肩动力稳定分析提供了一个新思路。
Shapai RCC arch dam is one of the few examples of a hundred-meter-high dam that has undergone a great earthquake test. The dynamic stability study is of great significance. In order to study the dynamic stability of the abutment under the same or higher seismicity and to combine the advantages of the finite element method with the rigid body limit equilibrium method, a finite element rigid body limit equilibrium method (FEM_LEM) based on multi-grid method Stability analysis method of abutment and abutment, and presents the limit cumulative displacement formula as the criterion of sliding block instability. The dynamic stability analysis of Shaba abutment under two kinds of seismic waves is carried out. Wave carried out the arch dam abutment stability overload analysis. The results show that under the action of artificial wave (ah = 2.05 m / s2) reflecting the “5.12” earthquake, the abutments of Shapai are stable, which is consistent with the actual seismic effect. Under the design wave (ah = 5.31 m / s2), the abutment on the left bank of Shapai will be unstable, while the right bank is still stable. In artificial wave overload analysis, the slip instability occurs when the left bank abutment sliders L1 and L2 are subjected to 3.2 and 3.6 times of artificial overloading respectively. The right bank abutment and shoulder sliders slip instability under the effect of 4.2 times overloading. The re-analysis of the dynamic stability of the sand abutment shoulder takes into account the influence of the slip direction of the slider and the transient change of the safety factor on the cumulative displacement of the slider, and more truly reflects the slip rule of the abutment slider of the Shapai arch dam. The actual dam dynamic stability analysis provides a new idea.