地震动下考虑各向异性土体-盾构隧道数值模拟

针对层状土体-盾构隧道地震反应分析，引入了横观各向同性弹塑性模型，建立了横观各向同性介质的双渐近-多向透射边界条件。针对盾构隧道抗震设计的特点，基于横观各向同性弹塑性模型，研制了考虑层状土体各向异性和施工开挖效应，适合于地下结构动力计算的弹塑性动力有限元程序。在程序中对不同的材料采用了不同的本构关系和单元形式，并采用了关联流动法则和多种屈服准则，可同时进行横观各向同性土体与地下结构的平面应力、平面应变和轴对称问题的静动力有限元分析。最后，利用所研制的程序对上海地铁二号线石门一路站附近区间隧道在不同超越概率地震波输入下的地震反应进行了计算。结果表明，在层状土体-地铁盾构隧道的抗震分析中考虑土体各向异性的影响是必要的，所提出的计算模型是合理易行的。

Numerical simulation of shield tunnel dynamic response to earth motions taking account of anisotropy of layered soil

The anisotropic elastoplastic model of layered soil is established to solve seismic response analysis of shield tunnel systems in layered soil. The doubly asymptotic multi-directional transmitting boundary for transversely isotropic medium is formed. Based on anisotropic elastoplastic model of layered soil, the dynamic finite element program of layered, transversely isotropic soil-structure dynamic interaction is developed according to the characteristics of aseismic design for shield tunnel. To simulate shield tunnel with finite element, various stress-strain models and element models are adopted in the program. The seismic response analysis of the district tunnel of Metro Line No.2 in Shanghai is carried out using the developed finite element program. The calculation results show that the dynamic finite element model of layered, transversely isotropic soil-structure is feasible and applicable. And the results show that it is necessary to take account of anisotropy of layered soil effect in the seismic analysis of shield tunnel system in layered soil.