水工隧洞衬砌结构非线性地震响应分析

Analysis on non-linear seismic response of lining structure of hydraulic tunnel

为了合理描述水工隧洞衬砌混凝土的非线性力学特性,采用塑性损伤模型模拟了混凝土材料在地震荷载作用下的本构关系。在此基础上,通过将混凝土刚度与钢筋材料刚度叠加来考虑衬砌中钢筋结构对衬砌刚度的强化作用,并基于此建立了衬砌结构非线性有限元分析模型。结合动力时程法模拟衬砌结构地震响应全过程,建立了完整的衬砌结构地震响应分析模型。通过将该模型应用于某水工隧洞地震响应数值计算中,分析了衬砌结构非线性地震响应特征。结果显示:地震过程中衬砌结构腰部的位移响应较大,衬砌结构整体产生了较为明显的结构变形,导致衬砌腰部最大拉应力达到了1.3MPa左右并超过了混凝土抗拉强度;震后衬砌结构内侧受到附加动水压力的影响,导致其损伤程度较大,损伤最为严重的区域主要分布在衬砌腰部,最大损伤系数达到了0.7左右。

In order to reasonably describe the non-linear mechanical properties of lining concrete,a plastic damage model is adopted to simulate its constitutive relation under seismic loading. On this basis,the reinforcing effect from the reinforcement structure in lining on the stiffness of lining is considered through superposing the stiffness of concrete with that of reinforcement material,from which a non-linear finite element analysis model for lining structure is established. Combining with dynamic timehistory method to simulate the whole process of seismic response of lining structure,a complete seismic response analysis model of lining structure is built up. Through applying this model to the numerical calculation of the seismic response of a hydraulic tunnel,the nonlinear seismic response characteristics of its lining structure are analyzed. The result shows that the displacement response of the waist of the lining structure during earthquake is larger and more obvious structural deformation occurs on the integral lining structure,which makes the maximum tensile stress at the waist of the lining reach to about 1. 3 MPa,thus surpass the tensile strength of the concrete. Due to the impact from the additional hydrodynamic pressure,the damage of the internal structure of the lining is larger after earthquake,of which the zones with the most serious damages are mainly distributed in the area of the waist of the lining with the maximum damage coefficient of about 0. 7.