重力坝层间抗滑稳定体系的动力可靠度分析方法

受明显的层状结构影响，加之材料参数和动荷载的双重随机性，动力条件下碾压混凝土重力坝的层间抗滑稳定可靠度问题值得关注。考虑地震波频谱特性、峰值加速度、坝体材料参数的随机性，统计概化出地震作用下坝体的潜在滑动失效路径；在特定地震动作用下，基于随机有限元分析结果，采用刚体极限状态判断准则和响应面法构建失效路径的动力抗滑稳定功能函数，进而求得其抗滑稳定可靠指标；接着考虑不同失效路径的相关性，用Ditlevsen窄界限公式估算体系的可靠度；最后，考虑地震动荷载的随机性，采用基于全概率公式的数值拟合积分方法求解大坝抗滑稳定体系的动力可靠度。研究结果表明，动力条件下，当水平地震系数大于0.2时，重力坝层间抗滑体系可靠度不再由建基面失效路径决定，而是由下游折坡处层面的失效路径决定。该方法数学意义明确，实用性强。

Dynamic reliability analysis method of anti-sliding stability between layers of gravity dams

Due to the randomness of dynamic loads and structural parameters,dynamic reliability of stability between layers of RCC gravity dam deserves the attention.Considering the randomness of spectrum characteristics and peak acceleration of seismic waves as well as material parameters of the dam,potential sliding paths of the dam subjected to earthquake can be identified by generalized statistics;based on stochastic finite element method(SFEM) results,the limit state function of dynamic sliding is built according to rigid limit state criteria and response surface method(RSM) under a certain seismic loading;the reliability index is got as well;then,considering the relativity between different failure paths,the reliability index of the system can be estimated by Ditlevsen narrow-bound method.Finally,the randomness of seismic load is taken into account,the numerical integration method based on complete probability formula is used to get the dynamic system reliability.The results indicate that the system reliability between layers of gravity dam no longer depends on the failure path of the foundation plane,but is closely related to the failure paths at the downstream fold slope when the horizontal earthquake coefficient is greater than 0.2.This method is mathematically clear and practical.