盾构近距离上穿越对已运营隧道的影响分析

Influence Analysis on Shield Tunnel Up-crossing Nearby Built Tunnel

上海市轨道交通8号线穿越2号线区间采用6 340mm土压平衡式盾构推进。基于现有的理论性成果,根据现场实测数据,对盾构穿越(上穿越)时,已运营隧道变形情况进行分析。证明盾构上穿越对下部隧道产生以隆起变形为主的影响,隆起变形呈抛物线,二次穿越中隧道变形具有叠合效应的规律,运营隧道变形在盾构脱离影响线前无明显变化,之后明显增大,且盾构脱离后变形仍继续发展,通过钢砂加荷使得已运营隧道变形趋于稳定。

Shanghai Metro No.8 Line tunnel is excavated by Ф6 340mm earth pressure balanced shield machine when it crosses No.2 Line. Based on theoretical results, combining with monitored field data, this paper analyzes deformation of No.2 line at up-crossing area. It proves that parabolashaped uplift mainly happens when shield machine up-crossing built tunnel, and it has adding effects when it crossing for second time. The deformation of built tunnel has no evidence change when shield machine is in influence lines, but it increases distinctly and develops when shield machine deviates from the line. The deformation can be controlled by loading the built tunnel with steel sands.