可流失充填型岩溶铁路隧道基底加固效应及处置方案

REINFORCEMENT EFFECT AND DISPOSAL SCHEME OF THE BASE OF THE RUNNABLE FILLING KARST RAILWAY TUNNEL

以陆家寨隧道为工程依托,采用FLAC3D建立三维数值计算模型,结合陆家寨隧道穿越暗河段隧周的岩溶地层特点,考虑岩溶充填物的可流失性,分别采用基底旋喷咬合桩加固,帷幕注浆加固和帷幕注浆+旋喷咬合桩加固3种加固措施,分析岩溶充填砂层流失前后对围岩位移、衬砌受力的影响,检验基底加固方案的可行性与基底加固的效果。研究结果表明:采用对基底进行旋喷咬合桩加固和帷幕注浆双重加固处理方案较好,受力方面大、小主应力数值减少较为明显,二次衬砌受力相对较小;位移方面,双重加固措施下隧道的位移变化较小,同时隧道开挖进程中,变化幅度也相对较小,综合来说,帷幕注浆+旋喷咬合桩加固方案对隧道施工影响更小,可为类似岩溶隧道地基加固工程提供借鉴。

Relying on the Lujiazhai tunnel,a three-dimensional numerical calculation model is established by using FLAC3D.Considering the characteristics of karst strata around the tunnel where the Lujiazhai tunnel passes through the underground river,and considering the loss of karst fillings,three reinforcement measures are taken,namely,base rotary jet grouting occlusive pile reinforcement,curtain grouting reinforcement and curtain grouting+rotary jet grouting occlusive pile reinforcement,to analyze the impact on surrounding rock displacement and lining stress before and after the loss of karst filled sand layer.Check the feasibility of the base reinforcement scheme and the effect of the base reinforcement.The results show that it is better to reinforce the basement with rotary jet grouting occlusive pile and curtain grouting,the values of large and small principal stresses decrease obviously,and the stress of the secondary lining is relatively small.In terms of displacement,the displacement of the tunnel under the dual reinforcement measures has a small change.At the same time,the range of change is relatively small during the tunnel excavation process.In general,the curtain grouting+jet grouting occluded pile reinforcement scheme has less impact on the tunnel construction,which can provide reference for similar karst tunnel foundation reinforcement projects.