三维整体模型对大型隧洞工程抗震性能的影响分析

Effects of global 3D model on aseismic performance analysis of large-span tunnels

三维整体模型和三维局部模型对大型隧洞的抗震动力分析具有一定的差别。本文以南水北调中线穿黄隧洞为例,利用显式有限元方法,考虑了材料非线性和接触非线性,以黏弹性人工边界来考虑对散射波能量的吸收和模拟半无限地基的弹性恢复力,研究三维整体模型对大型隧洞工程抗震性能的影响。计算结果表明:采用三维整体模型仿真分析,竖井、引水管道、盾构片等关键结构在沿管轴线方向的位移响应均大于局部模型的相应结果;整体计算模型能够反映局部模型所不能反映的内、外衬等大跨度结构的整体动力响应。由此可见,以三维整体模型为研究对象,能够更全面、更准确地研究大跨度地下结构的动力特性。

Global model and local model show different results in analysis of aseismic performance of large-span tunnels.This paper adopts a global 3D model and a local 3D model considering material nonlinearity and contact nonlinearity to simulate the Yellow River crossing tunnel with explicit finite element method,and uses artificial boundary conditions of viscoelastic type to absorb scatting wave energy in simulation of elastic restoring force of the semi-infinite foundation.Results show that the global model produces larger axial displacements of key structures than the local one,such as shafts,inner tunnels and external shields,and it can capture the global response of the long-span such as inner tunnels or external shields that the local model cannot.Thus,a global 3D model is necessary in a thorough and accurate study of large-span underground structures.