两侧深基坑开挖对近邻地铁车站及隧道变形影响的优化分析

基坑周围环境的保护要求日趋严格,基坑工程近邻地铁车站和隧道的情况亦日益常见。为此,优化基坑开挖方案以控制车站和隧道的变形则至关重要。以天津市某与地铁车站贴建的深基坑工程为背景,采用考虑土体小应变硬化特性的有限元方法,结合3种不同开挖顺序的施工方案,分析两侧基坑开挖对既有车站和隧道变形的影响。计算结果表明,在控制车站和隧道变形方面,对称开挖的施工方案最优,合理制定两侧基坑开挖的顺序能有效控制车站和隧道的水平位移,但对隧道沉降的控制效果不明显;非对称开挖时,先施工小基坑优于先施工大基坑。

Optimal Analysis of Influences on Deformation of Adjacent Metro Station and Tunnel Due to Deep Pit Bilateral Excavations

The protection of the environment around pit excavation is becoming more stringent and common for adjacent metro stations and tunnels. And in order to control the deformation of the stations and the tunnels,it is of the most importance to optimize the excavation program. According to the practice of deep excavation adjacent to a metro station and a tunnel in Tianjin,three construction schemes are designed to analyze the interactive impact on the adjacent metro station and tunnel caused by bilateral deep excavations with finite element method addressing small strain hardening soil. The results show that symmetric excavation method is most optimal to control the deformation of the station and tunnel,and reasonable excavation sequence is effective to control the horizontal deformation,but not effective to control the settlement of the tunnel. For the asymmetric excavation,it is advisable to conduct small pit excavation before large one.