走滑断层位错作用下城市地铁隧道损伤分析

为了能够较快速、较准确地估计出穿越活断层城市地铁隧道的抗震薄弱部位，基于拟静力弹塑性有限元方法，以北京地铁7号线工程的区间隧道作为研究对象，采用数值模拟的方法研究了在走滑断层位错作用下地铁隧道的非线性反应。通过在数值计算模型中嵌入合理的损伤塑性本构模型，利用损伤指标研究了走滑断层下衬砌结构的破坏形式，重点分析了结构损伤的开始部位、发展过程以及最终的损伤程度，并建立了能够估计结构损伤范围及破坏最严重位置的统计关系式。结果表明，在走滑断层作用下衬砌结构出现损伤的区域主要发生在活断层附近一定范围内，拱腰部位的损伤最为严重；增加基岩上覆土层厚度能够减轻衬砌结构的破坏程度，当基岩上覆土层厚度大于等于临界覆盖土层厚度时可以不考虑走滑断层断裂对于浅埋隧道的影响。衬砌结构损伤区域长度与震级的大小和土层厚度有关，损伤最严重的位置随土层厚度的变化而改变。研究成果为穿越活断层地铁隧道的抗震设计和安全性评价提供了参考依据。

Damage analysis of urban metro tunnel under strike-slip fault

In order to estimate the seismic weak parts of a crossing-active fault urban metro tunnel more fastly and accurately, the finite element method of pseudo-static elastoplasticity is used for numerical simulation to nonlinear reaction of metro tunnel by strike-slip fault, taking the range of Beijing metro line 7 as an study object. Based on the established reasonable damage plastic constitutive model, damage index is adopted to research the failure mode of lining structure, especially the first position, process and final degree of damage. The statistic formulas estimating structural damage region and the most severely location are developed. The results show that: the damage range of lining structure is located in active fault under the effect of strike-slip fault; the destruction is the most serious at the hance. The degree of lining destruction can reduce with the increase of the ground thickness. It does not need to worry about the effect of strike-slip fault rupture on the shallow tunnel when the soil thickness is greater than or equal to the critical value of soil thickness. The damaged range of liner is related to magnitude and soil thickness, and the location of the most serious damage changes along with soil thickness. The obtained results play an important role in seismic design and safety evaluation.