双洞单轨地铁区间隧道非线性地震反应分析

Analysis of nonlinear earthquake response of metro double-tunnels

本文采用大型商业有限元软件ABAQUS对南京地区双洞单轨地铁区间隧道的非线性地震反应特性进行了数值模拟。采用作者提出并在ABAQUS软件上开发实现的土的动粘弹性模型模拟土的动力非线性,采用Jeeho Lee.提出的混凝土动力塑性损伤模型模拟隧道管片混凝土在循环荷载下的非线性特性。数值分析表明:隧道最大动应力反应的位置将发生在与洞顶约成45°角的位置,在100年超越概率63%的地震作用下区间隧道结构是基本安全的,但在100年超越概率10%和3%的地震作用下,南京地铁区间隧道可能会发生很大的拉应力和剪应力反应,有可能在与洞顶约成45°角的位置产生地震裂缝。因此建议隧道管片接缝应避开该位置,同时对该位置的管片应加强其抗拉和抗剪强度。

The nonlinear earthquake response of metro double-tunnels built in Nanjing is analyzed by ABAQUS finite-element software. In this numerical analysis, the nonlinear characteristics of soil under cyclic loading are modeled by a dynamic elastoplastic constitutive model founded by the authors which is implemented in ABAQUS software. The nonlinear characteristics of concrete under cyclic loading are modeled by plastic-damage constitutive model founded by Jeeho Lee. The analysis results indicate that the maximal earthquake stress response of tunnels is located in an angle of 45° to the top of tunnels. The tunnels subjected to earthquake for probability of exceedance 63% in 100 years are secure. However, the tensile and the shear stress responses of tunnels subjected to earthquake for probability of exceedance 10% or 3% in 100 years are large and close to the limit stress values of concrete. The cracks will develop possibly in the locations of 45 ° to the top of tunnels. For shield tunnels, the joint of duct pieces should be away from these worst locations. At the same time, the duct pieces of shield tunnels these locations should be strengthened.