地震作用下地下厂房混凝土衬砌结构稳定分析

Stability analysis of concrete lining structure in underground powerhouse with seismic action

针对混凝土循环荷载作用下的率相关性和疲劳损伤特性,提出考虑拉、剪损伤各向异性的混凝土动力本构模型,并推导出损伤变量动态演化方程;针对围岩与衬砌动力相互作用特点,提出考虑围岩与衬砌非连续变形的显式动力有限元积分方法;由此,构建地下厂房混凝土衬砌结构动力响应分析方法,并将该方法应用于映秀湾水电站地下厂房抗震稳定计算。衬砌结构各部位在地震下处于同步震动状态,其中衬砌顶拱应力和位移波动幅度较大;主厂房衬砌顶拱与边墙最大相对位移达到1.6 cm,说明主厂房发生了较为明显的结构变形;衬砌结构损伤区主要分布在顶拱处,其中拉裂损伤造成的损伤破坏较为严重;围岩对衬砌结构的约束作用有助于衬砌结构的抗震稳定性。应用上述方法所得的计算结果较为合理地反映了衬砌结构动力响应特征,可为地下厂房混凝土衬砌结构抗震设计提供参考。

Based on rate-dependant and fatigue damage characteristics of concrete under cyclic loading, a dynamic constitutive model that considers tension and shear damage anisotropic was proposed, and the evolution equations of damage variables were derived. According to dynamic interaction characteristics of surrounding rock and lining, a explicit dynamic finite element analysis method that considers the discontinuous deformation between surrounding rock and lining was presented. Thus, a dynamic response analysis method of concrete lining structure in underground powerhouse was constructed and then applied to calculate seismic stability of Yingxiuwan Hydropower Station. The results show that various positions of lining structure are in a synchronous vibration state, but the stress and displacement response of the top arch are larger than that of other positions. The maximum relative displacement of the top arch and side wall of the main powerhouse reaches 1.6 cm, indicating that the main building has a obvious structural deformation. Damage zone of lining structure is mainly distributed in its top arch, and the damage caused by tension is more serious.The confinement effects of the surrounding rock to the lining structure is helpful for seismic stability of the lining structure.Calculation results from the proposed method reflect seismic response characteristics of concrete lining reasonably,and thus provide references for seismic design of concrete lining in underground powerhouse.