瘦西湖超大直径盾构隧道施工对周边环境影响分析

大直径曲线盾构隧道中,盾构掘进时盾构对其两侧和拱顶上方的土体作用不同,不同位置土体表现出不同的变形规律。为了保证曲线盾构隧道施工安全进行,并针对变形的差异性提出相应的解决方案,采用现场监测和FLAC 3D数值模拟相结合的方法,对超大直径曲线盾构隧道施工中周边土体变形进行分析,监测项目包括地表沉降、分层沉降、土体深层水平位移。研究结果表明:1)随着隧道掘进,地表沉降呈现反"S"形变形趋势,与3个变形阶段对应,即盾构切口到达时缓慢隆沉,盾构通过时沉降较快,盾尾脱出时沉降趋于稳定;2)横向沉降槽曲线中,掘进时隧道掘进方向曲线内侧沉降量比外侧对称位置沉降更大;3)土体水平位移在隧道掘进方向曲线内侧变形量小于外侧变形量。

Influence of Super-large Diameter Shield Tunneling on Surrounding Environment:Case Study on Slender West Lake Crossing Tunnel in Yangzhou,China

The surrounding ground will be disturbed when a large diameter shield bores in curved section. In the paper, analysis is made on the influence of a super large diameter shield tunneling on the surrounding environment by means of site monitoring and FLAC 3D numerical simulation, so as to guarantee the safety of the construction and to provide a solution for the deformation difference. The monitoring items include ground surface settlement, layered settlement and deep horizontal displacement of soil. The study results show that: 1) The ground surface settlement takes place in 3 stages, i.e., when the cutting ring of the shield reaches, the rate of the ground surface settlement is low; when the shield passes, the rate of the ground surface settlement is high; when the shield tail passes, the rate of the ground surface settlement becomes stable; 2) The ground surface settlement on the inner side of the curved tunnel section is larger than that on the outer side of the curved tunnel section; 3) The horizontal displacement of ground on the inner side of the curved tunnel section is smaller than that on the outer side of the curved tunnel section.