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为了得到隧道围岩结构的地震动安全系数,借助通用有限元软件ANSYS,首先对水平地震作用下的模型进行模态分析,得到质量阻尼系数和刚度阻尼系数;其次由静力分析模型得到竖向边界上的水平向支座反力,然后将结构自重转化为温度边界条件,通过热分析得到模型各节点的温度,从而实现在动力分析中考虑重力的影响;最后采用悬臂梁动力分析模型,导入热分析获得的模型各节点的温度,并在竖向边界上施加水平向支座反力,通过不断折减围岩塑性区的凝聚力c和内摩擦角Φ,直到计算不收敛为止,从而得到隧道围岩结构的地震动安全系数。数值算例结果表明:采用的方法是可行的,将围岩结构自重转化为节点温度的措施解决了以往动力分析不能考虑结构自重的难点,进而为以后地震作用下隧道动力安全系数的计算及其工程应用提供了理论依据。
In order to get the seismic safety factor of the tunnel surrounding rock structure, the model of the horizontal seismic action is modeled by the general finite element software ANSYS to get the mass damping coefficient and the stiffness damping coefficient. Secondly, the vertical And then the self-weight of the structure is transformed into the temperature boundary condition. The temperature of each node in the model is obtained through thermal analysis so that the influence of gravity can be considered in the dynamic analysis. At last, the cantilever beam dynamic analysis model is adopted to import The temperature of each node in the model obtained by thermal analysis was analyzed by thermal analysis, and the horizontal bearing reaction force was imposed on the vertical boundary. By continuously reducing the cohesion c and the internal friction angle φ in the plastic zone of the surrounding rock, the tunnel was obtained until the calculation did not converge Earthquake safety factor of surrounding rock structure. Numerical examples show that the method is feasible, and the measures of converting dead weight of surrounding rock mass into node temperature can solve the difficulty that dynamic analysis can not consider the weight of the structure, and then calculate the dynamic safety coefficient of tunnel under earthquake Engineering provides a theoretical basis.