天津Z2线工程软土场地震陷分析

Seismic Settlement Analysis of Soft Soils of Tianjin Z2 Line

天津Z2线轨道交通工程地处滨海软土地区。基于《软土地区岩土工程勘察规程》中简化的分层总和法,采用一维土层非线性地震响应分析程序EERA替代Seed经验公式计算土层的动应力,同时采用修正的软土残余应变势简化计算公式,开展了天津Z2线全部98个钻孔的软土震陷计算。结果表明,地表震陷主要源自较浅土层,地表深度20 m以下的震陷可不考虑;隧道由地下线过渡到高架线的上升段震陷较大,应考虑采取防控措施;场地震陷主要由淤泥质土层产生,占地表震陷的70%~80%以上。研究对于类似工程具有一定参考价值。

The Tianjin Z2 line project is located in the soft soil area,with large risk of seismic settlement.Based on the simplified layer-wise summation method by specification for geotechnical investigation in soft clay area(JGJ 83-2011),this paper calculated seismic settlement of 98 boreholes along the Tianjin Z2 line.During calculation the one-dimensional soil layer nonlinear seismic response analysis program EERA was utilized to calculate the dynamic stress of soil,instead of the empirical formula proposed by vSeed,and the recently modified simplified formula of residual strain potential in soft soil was employed.The results showed that,the seismic settlement can be ignored in small earthquakes;seismic settlement below the surface depth of 15 m may not be considered in the moderate and major earthquakes.The seismic settlement is large in the rising section of the tunnel from the underground line to the elevated line,and prevention and control measures should therefore be taken.The seismic settlement is mainly caused by the mucky soil layer.The research is valuable for the seismic design of similar projects.