基于有限元盾构开仓开挖面稳定性及施工技术研究

以广州地铁4号线塘—大区间盾构隧道为依托,针对盾构开仓开挖面稳定及施工技术展开研究。采用有限元分析方法,对盾构开仓开挖面破坏形式、开挖面变形和开挖面前方地表沉降三方面进行稳定性分析,得到相应规律;从盾构开仓刀盘后止水措施、开挖面泥膜质量控制和盾构开仓期间监测措施三方面对盾构开仓开挖面稳定施工技术进行研究,并提出主要相关参数。盾构开仓期间,利用盾构外壳预留孔采用高压注浆方式向盾构周边注入1.10~1.15 g/cm;的高粘度浆液,以免浆液流失;工程遵循"高稠度、高密闭、低比重、易成膜"措施,调整泥浆参数,同时对所选泥浆材料进行优化;采取加密监测频率方式,周边地表监测频率为8次/d。最后给出开挖面异常工况处理措施,并将该方案应用于实际,取得良好效果,为大湾区盾构开仓开挖面稳定提供工程参考。

Study on Stability and Construction Technology of Shield Cabin Opening Excavation Face Based on Finite Element Method

Based on the shield tunnel in Tangkeng-Dayong section of Guangzhou Metro Line 4,the stability of shield opening excavation surface and construction technology are studied.Using the finite element analysis method,firstly,the failure form of the shield opening excavation surface,the deformation of the excavation surface and the surface settlement in front of the excavation surface are analyzed,and the corresponding laws are obtained;secondly,the stable construction technology of shield opening excavation face is studied from three aspects:water stop measures behind shield opening cutter head,mud film quality control of excavation face and monitoring measures during shield opening,and the corresponding parameters are put forward.The results show that:(1)during the opening of the shield,the reserved hole of the shield shell is used to inject 1.10~1.15 g/cm;high viscosity slurry into the periphery of the shield by means of high-pressure grouting to avoid slurry loss;(2)the measures of“high consistency,high sealing,low specific gravity and easy film formation”are followed in the project,the mud parameters are adjusted,and the selected mud materials are optimized;(3)adopting the method of densifying the monitoring frequency,and the surrounding surface monitoring frequency is 8 times/day.Finally,the measures to deal with the abnormal working conditions of the stratum on the excavation surface are given,and the scheme is applied to practice,which has achieved good results,so as to provide engineering reference for the stability of the shield opening excavation surface in Dawan district.