下穿运营线路的黄土塬盾构隧道的施工风险与对策

Construction Risks of the Shield Tunnel Undercrossing the Operating Line in Loess Platea Area and Its Countermeasures

以位于黄土塬区的引汉济渭二期工程南干线引水隧洞为依托,探讨分析了黄土塬地区盾构引水隧洞下穿高速公路路基段和运营线路造成的地层扰动影响,在此基础上提出加强注浆、地层预加固、控制盾构土仓压力及出土量等措施以减少地层不均匀沉降的施工风险;针对盾构掘进穿越黄土塬区地层时,由于地下水位高,砂土渗透性强导致掘进困难,每环掘进漏泥多,清理时间长,盾尾涌水及螺旋出土机喷涌现象频繁发生的问题,研究了盾构喷涌的形成机理,据此制定了渣土改良、盾构掘进参数优化等防喷涌的施工对策;形成了针对黄土塬区盾构法引水隧洞下穿运营线路的施工风险分析与对策,为现场作业和相似工程提供施工指导。

Based on the diversion tunnel of the south main line in PhaseⅡof Hanjiang-to-Weihe River Water Diversion Project in the loess platea area,this paper discusses and analyzes the influence of formation disturbance caused by the shield diversion tunnel under the subgrade section of the expressway and operating line in the loess platea area.On this basis,measures such as strengthening grouting,pre-strengthening of strata,controlling shield soil bin pressure and excavation amount are proposed to mitigate construction risks associated with uneven formation settlement.The study also investigates on the gushing formation mechanism of shield tunneling through loess platea areas to address challenges related to high groundwater levels,strong sand permeability,significant mud leakage per ring,prolonged cleaning time,water gushing at shield tail,and frequent spouting of screw excavators.Consequently,anti-spouting construction countermeasures including slag improvement and optimization of shield tunneling parameters are formulated.Construction risk analysis is conducted for underpass operation lines in loess platea areas along with corresponding countermeasures to provide guidance for field operations and similar projects.