深厚软土场地道路隧道结构横向地震响应分析

Analysis of Lateral Seismic Response of Road Tunnel Structure in Deep Soft Soil Area

确定场地范围和地震输入方式是道路隧道地震响应分析的前提。以上海深厚多层软土场地的自由场解析为基础,验证2D有限元模型的场地基岩和侧向边界假定的合理性;进而选取典型盾构法和明挖法隧道为研究对象,建立有限元2D地层-隧道地震动力响应分析模型,分析评价合理的基岩面深度与侧向边界宽度。结果表明:深厚软土场地的隧道地震响应分析应采用黏弹性人工边界以合理实现自由场边界;侧向边界的选取范围对隧道的动力响应影响较小,计算模型的底部边界深度对响应影响较大;取70 m深度为基岩面得到隧道结构地震动力响应是偏于安全的,但场地的基频有所变化。

The determination of site scope&seismic input mode is the premise of seismic response analysis of road tunnel.Based on the free field analysis of Shanghai deep multi-layer soft soil site,the rationality of the site bedrock&lateral boundary assumption of 2D finite element model is verified;then,the typical shield method&opencut tunnel are selected as the research objects,and the finite element 2D stratum tunnel seismic dynamic response analysis model is established to analyze&evaluate the reasonable bedrock surface depth&lateral boundary width.The results show that the viscoelastic artificial boundary should be used to reasonably realize the free field boundary in the seismic response analysis of deep soft soil site;the selection range of lateral boundary has little influence on the dynamic response of the tunnel,and the depth of the bottom boundary of the calculation model has a greater influence on the response;taking the depth of 70 m as the bedrock surface to obtain the seismic dynamic response of the tunnel structure is safe,but the fundamental frequency of the site changes.