混凝土坝地震动力损伤分析  

DYNAMIC DAMAGE OF CONCRETE GRAVITY DAMS UNDER EARTHQUAKE EXCITATION

作　　者：杜成斌[1] 苏擎柱[1] 

机构地区：[1]河海大学土木工程学院,南京210098

出　　处：《工程力学》2003年第5期170-173,共4页Engineering Mechanics

摘　　要：基于塑性损伤本构理论,将损伤变量作为内变量,在Drucker-Prager本构模型中引入损伤变量,考虑材料损伤引起的材料劲度的退化,基于非关联流动法则计算材料的塑性应变,根据材料的有效塑性应变计算损伤量,考虑到张开裂缝闭合时材料弹性劲度的恢复,推导了考虑塑性损伤的混凝土动态本构关系,并给出了内变量的计算步骤和动力方程的迭代格式。最后利用建立的动态本构模型对Koyna重力坝进行了非线性地震响应时程分析,并给出了关键时刻坝体最大受拉损伤分布,结果表明在坝颈和坝基处出现了较大的损伤,坝颈处的损伤最终形成由下游向上游的开裂破坏,这与该坝的实际震害较为一致。A new plastic-damage constitutive model for cyclic loading of concrete has been developed for the seismic analysis of concrete dams based on plastic-damage theory. Damage variable is used as an internal variable, which is included in the Drucker-Prager yield function. Stiffness degradation induced by material damage is considered in the model. The plastic strain rate is obtained according to the nonassociative flow rule. Damage evolution is determined by effective plastic strain. The crack opening/closing behavior is modeled as elastic stiffness recovery during elastic unloading from a tensile state to a compressive state. The main steps of the algorithm for the internal variable and nonlinear dynamic equation are presented in the paper. The plastic-damage model is used to evaluate the response of Koyna dam, and maximum damage distributions at different time are given in the analysis. The analysis shows that there occur two localized large tensile damages, one is at the change of downstream slope, and the other is at upper region of the bottom. Crack failure is formed from the downstream at the change of slope to upper of the dam at last. The evolution of damage is consistent with the observed cracking in the dam.

关 键 词：塑性损伤 混凝土重力坝 本构模型 非线性 地震分析 

分 类 号：TV642.3[水利工程—水利水电工程] TV312