南京复杂地层中盾构掘进地表沉降实测数据分析

Measurement and Analysis on Surface Subsidence Induced by Shield Tunneling in Complex Stratum of Nanjing

通过现场实测数据,分析了南京至高淳城际快速轨道工程TA04标段3号盾构井—胜太路站区间隧道不同埋深、地质及施工参数条件下,盾构施工对地表沉降的影响规律。实测结果表明:盾构在上软下硬复合地层施工时地表沉降值显著大于在全断面硬岩地层施工工况,土舱压力对上软下硬复合地层开挖面稳定影响较大;全断面硬岩地层盾构施工引起的地表沉降值几乎不受埋深、土舱压力及同步注浆等变化的影响。结合施工过程中刀具磨损、开挖面结泥饼等施工难点,提出了根据硬岩与上软下硬复合地质条件盾构施工分别采取欠压推进和保压推进等技术措施,取得了良好效果。

The site monitoring data of tunnel between No. 3 working shaft to Shengtai Road which is part of the TA04 tenders of inter-city rapid rail project from Nanjing to Gaochun were analyzed. The data shows that the surface subsidence is much larger when the shield excavate in the composite stratum than in the rock stratum. In addition, the cabin pressure has great influence on stability of excavation face. The data also shows that the surface subsidence is almost unaffected by different depth, cabin pressure and synchronous grouting quantity when the shield excavate in the rock stratum. Finally, in consideration of the construction difficulties like tool wear, excavation face incrusted with mud and so on, technical measures were given. That is, low cabin pressure were set and in the rock stratum and high cabin pressure were set in the composite stratum when the shield passed through. The measures achieved good results.