公路隧道穿越急倾斜采空区的治理技术

Treatment Technology of Highway Tunnel through Steep Inclined Goaf

针对目前公路隧道穿越采空区的研究热点,以成渝高速公路(复线)巴岳山隧道为研究对象,介绍了急倾斜采空区治理技术现状,对公路隧道穿越急倾斜采空区治理的原则进行了总结,计算了巴岳山隧道急倾斜采空区对隧道稳定性的影响,并结合急倾斜采空区治理实践,对隧道穿越急倾斜采空区治理技术进行了分析。研究表明,急倾斜采空区治理应首先对隧道上部采空区进行超前支护,然后对围岩塑性变形区进行加固。实践证明,利用注浆加固技术强化采空区围岩结构,并配合双层小导管超前支护措施在公路隧道急倾斜采空区治理中具有重要推广价值。巴岳山隧道采空区影响段现场监控量测结果显示,治理技术方案实施40 d后,格栅拱架应力基本稳定在1.2～1.8MPa,各监测断面水平收敛和拱顶沉降总变形量均未超过40 mm。

Focusing on the research hotspot of highway tunnel passing through goaf and taking Chongqing Bayueshan tunnel in Chengdu-Chongqing expressway as the research object, the current status of treatment technology of steep inclined goaf was introduced, the treatment principle of highway tunnel passing through steep inclined goaf was summarized, the effect of steep inclined goaf on the stability of Bayueshan tunnel was calculated. Combining with the treatment practice of steep inclined goaf, the treatment technology of tunnel passing through steep inclined goaf was analysed. The results show that the first step of treatment work is to carry out advanced support, mainly support the goaf in the upper of tunnel, then to strengthen the plastic deformation area of surrounding rocks. The practice shows that using grouting reinforcement technology to strengthen the rock structure around goaf meanwhile combined with advanced support of two-layer ductules have important popularization value in treatment of tunnel passing through steep inclined goaf. The site monitoring result of goaf influenced parts of Bayueshan tunnel shows that the stress of lattice girder is basically steady in the range of 1.2 - 1.8 MPa, both the total deformation of horizontal convergence and the vault sedimentation of each monitoring cross-section do not exceed 40 mm.