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针对设计地震动的变异性,提出了地下隧道抗震安全性分析的蒙特卡罗方法。1建立地下隧道非线性地震响应分析模型。采用粘弹性边界方法和地震动输入等效节点力方法模拟半无限场地的地震激励,结合通用有限元软件ANSYS,建立地下隧道地震响应分析模型,模型采用等效线性化方法模拟土体非线性,采用瑞利阻尼和材料阻尼相结合方法模拟土体阻尼,分别考虑衬砌中混凝土和钢筋的非线性,并考虑衬砌和土体之间的接触问题。2确定设计地震动,然后利用模拟产生目标谱符合某一设计地震动时变功率谱的非平稳地震动模拟方法,产生若干条与设计地震动具有同一统计特征的非平稳地震动。3进行样本地震动激励下的地下隧道非线性地震响应分析,求得地下隧道地震响应的变异性。该研究为地下隧道抗震安全性分析提供了一种简单实用的方法,对地下隧道抗震设计有一定的参考价值。
Aimed at the variability of design ground motions, a Monte Carlo method for seismic safety analysis of underground tunnels is proposed. 1 Establish a nonlinear seismic response analysis model of underground tunnel. The viscoelastic boundary method and the equivalent nodal method of ground motion input are used to simulate the seismic excitation in the semi-infinite field. Combined with the general finite element software ANSYS, the seismic response analysis model of the underground tunnel is established. The equivalent linearization method is used to simulate the soil nonlinearity, The damping of soil is modeled by a combination of Rayleigh damping and material damping. The nonlinearities of concrete and steel in the lining are considered respectively, and the contact between lining and soil is considered. Secondly, the non-stationary ground motions with the same statistical characteristics as design ground motions are generated by simulating the non-stationary ground motions simulated by simulating that the target spectrum meets the time-varying power spectrum of a designed ground motions. 3 Nonlinear seismic response analysis of underground tunnel under earthquake excitation of samples is carried out to obtain the variability of underground tunnel seismic response. The study provides a simple and practical method for seismic safety analysis of underground tunnels and has certain reference value for the seismic design of underground tunnels.