基于挡墙变位诱发的地表沉陷分析开挖安全状态

Analysis of Excavation Safety State Using Ground Settlement Induced by Retaining Wall Movement

本文以杭州紫金港隧道开挖工程为背景,采用位移有限元方法模拟挡墙变位所诱发的地表沉陷,进而评估开挖施工期的安全状态。数值模拟得到了挡墙变位诱发地表沉陷的基本规律,并以最大地表沉陷(wm)与最大挡墙变位(um)的比值(wm/um)来评估基坑的安全状态。研究表明,伴随基坑开挖的进行,墙后土体塑性区逐渐得以发展,比值wm/um也随之呈现逐渐增大的发展趋势,并最终趋于某一临界拐点值。在给定的挡墙位移模式下,wm/um值的大小与基坑安全度之间存在特定相关性。

This study focuses on the excavation work in Zijingang Tunnel project. The displacement-FEM technique has been employed to model the ground settlement induced by the movement of retaining wall and then assess the potential safety state of excavation. The numerical analysis has demonstrated the basic relationship between movement of retaining wall and its induced ground settlement. The ratio wm/ umof the maximum surface settlement( wm) to the maximum retaining wall movement( um) is then used to assess the safety state of excavation. This analysis has found that during the excavation construction,the ratio of wm/ umwas increasing with the development of plastic strain of soil behind the retaining wall,and eventually approaching certain critical value. With respect to a given wall movement mode,there will be a specific relationship between wm/ umand safety factor.