重力坝的塑性极限分析法

Plastic limit analysis method for gravity dam

应用结构塑性极限分析的上、下限定理及相应的有限元法分析重力坝的极限承载能力,以判断大坝的稳定性。在上限法中,考虑变形相容条件、外荷载做正功和内功功率与外功功率相等,求得了重力坝超载系数和强度储备系数的上限值及相应的机动容许位移(增量)场。在下限法中,考虑平衡条件、应力边界条件、屈服条件以及应力间断条件,求得了超载系数和强度储备系数的下限值及相应的静力容许应力场。文末给出的算例说明,本文在重力坝的抗滑稳定分析时提出的塑性极限分析法比弹塑性有限元法、摩擦公式和抗剪断强度公式更准确。

The upper bound and lower bound theorem of classical plasticity theory and corresponding FEM is applied to analyze the bearing capacity of gravity dam for judging the stability of the dam.In the approach of determining the upper bound,the deformation compatibility is considered,the work done by external load is prescribed on position and the power of the external forces is equal to the power of external forces.Consequently,the overload factor and strength safety coefficient of the gravity dam as well as the corresponding kinematically permissble velocity field can be obtained.In the approach of determining the lower bound,the conditions of equilibrium,stress boundary,yielding and stress discontinuity are considered,and the overload factor and strength safety coefficient of the gravity dam as well as the corresponding statistical permissible stress field also can be obtained.The comparison of this method with elastoplastic FEM and slide resistance analysis for a gravity dam is presented.It shows that this method gives the most reasonable result.