【摘要】 针对混凝土重力拱坝的特点,基于混凝土弥散裂缝模型,采用三维非线性有限元法,以坝体位移响应突变、坝基塑性区贯通、坝体开裂破坏以及计算收敛性作为重力拱坝体系整体失稳的判断准则,探讨了重力拱坝整体安全度评价的方法。以国内某重力拱坝为例,从上游水压超载、坝基强储、地震灾变等方面对其整体安全度做出评价,揭示重力拱坝的薄弱部位,为其优化设计及抗震安全评价提供依据。研究表明:不同破坏模式下,该重力拱坝因水压力超载引起系统失效的整体安全度为5.0;坝基岩体抗剪强度降低使系统失效的整体安全度为3.5;地震灾变引起系统失效的整体安全度为1.7;重力拱坝的破坏模式区别于拱坝,水压力超载破坏主要表现为坝肩中下部开裂破坏和坝基岩体屈服破坏导致整体失稳;基岩强度折减破坏主要表现为坝体沿坝基面的滑动失稳破坏;地震灾变破坏主要表现为坝踵、溢流道闸墩底部的开裂破坏,其中,溢流道闸墩是坝体相对薄弱的高地震响应区。更多还原

【Abstract】 According to the structural characteristics of gravity arch dams,a 3D nonlinear finite element method based on smeared-crack model is used in this paper to evaluate the global safety degree(GSD) of a gravity arch dam.The displacement mutation,plastic zone connectivity,dam failure modes and calculation convergence are suggested as criteria to estimate the safety of the concrete gravity arch dam system.Taking a domestic concrete gravity arch dam as an example,its global safety degree is evaluated by the overload of upstream water pressure method,shear strength reduction of rock method and overload of seismic intensity method.Based on the results of comprehensive evaluation we point out the weak part of the dam,and provide a theoretical basis for optimization design.The results indicate that GSD under upstream overloading water pressure is about 5.0;GSD under shear strength reduction of rock in dam foundation is about 3.5;GSD under earthquake is about 1.7.The failure modes of concrete gravity arch dam are different from the general arch dam.It may fail because of the lower dam abutment damage and the base rock yield caused by upstream overloading water pressure.With the reducing of the shear strength of rock,sliding may occur because of the base rock failure.Cracking damage,causes the failure of the dam-rock system under earthquake.It is mainly located at the dam heel and the base of the spillway pier which are considered to be the relatively weak parts under earthquake.更多还原