库水压缩性及分缝布置对拱坝非线性地震响应的影响

Influence of Reservoir Water Compressibility and Joint Layout on the Nonlinear Seismic Responses of an Arch Dam

构建了一种较为综合全面的高拱坝-库水-地基动力相互作用模型,该模型通过采用声学单元模拟库水,以考虑库水与坝体及地基的耦合;采用动接触-联结混合模型中能够实现接触面间法向光滑过渡的指数型动接触力模型模拟横缝接触非线性;在混凝土受拉(压)本构模型中引入动力放大系数实现混凝土损伤塑性模型的率型化.对锦屏Ⅰ级高拱坝-库水-地基系统模型进行了地震响应分析.结果表明:在横缝模型中考虑库水的压缩性,会使坝踵处动水压力峰值减少32.20%,对拉应力影响较大,使横缝开度最值减少且可能出现在左、右岸坝肩区域内;考虑库水可压性时,不设横缝模型的坝踵及左岸坝肩处出现了受拉损伤因子大于0.7的集中区域,对比而言设置横缝模型的坝体损伤程度有明显改善,表明横缝的存在使得拱向应力向梁向应力转化,改善了坝肩的受力状况.

In this paper,a comprehensive three-dimensional model of the high arch dam-reservoir-foundation dynamic interaction was established.The acoustic elements were employed to simulate the reservoir water,and the coupling between reservoir water and dam body,reservoir water and foundation was considered in this model.An exponential dynamic contact force model which can realize the transition from normal to smooth contact surface was used to simulate the nonlinearity contact of transverse joints.The dynamic amplification factor was introduced into the constitutive model of concrete under tension(compression)to realize the rate effect modeling in the concrete damage plasticity model.The seismic response analysis of the JinpingⅠarch dam-foundation-reservoir system was performed.The results show that the hydrodynamic pressure was reduced by 32.20%,and the tensile stress was greatly affected when the compressibility of reservoir water was considered in the transverse joint model.The maximum value of with the transverse crack opening was reduced,and it may occur in the left and right abutment area.A concentrated area with a tensile damage factor greater than 0.7 appears at the heel and left abutment of the arch dam without transverse joints model when the compressibility of reservoir water was considered.By contrast,the damage degree of the dam body was significantly improved by the model with transverse joints,which indicates that the existence of transverse joints can transform the arch stress to beam stress and improve the stress state of the dam abutment.