高速铁路隧道含水砂层段帷幕注浆方案设计

Design of Curtain Grouting Scheme for Water-bearing Sand Section for High-speed Railway Tunnel

为了解决新近系未成岩含水砂层段隧道施工中出现的流砂难题,提出一种采取帷幕注浆加固结合地表降水措施的治理方案,依据理论结合实际工程经验,确定银兰高铁某隧道105 m段内第一至第五循环帷幕注浆合理的注浆范围等参数,并针对注浆中出现的问题及时调整设计参数。对于第二、五循环出现的溜塌及塌腔问题,分析病害原因后给出了相应的解决方案。研究结果表明:(1)注浆方案中,止浆岩盘厚5 m,止浆墙厚1.5 m,每循环注浆长25 m,注浆压力为3~5 MPa;(2)帷幕注浆孔数过少会弱化固结效果,进而引发塌方等异常情况;(3)围岩中的孔隙水排出不及时会使砂岩和固结体软化,注浆回填时浆液未充满塌腔或固结效果不佳会加大管棚及套拱的荷载;(4)采用ϕ108 mm管棚结合ϕ42 mm小导管超前支护可有效解决第五循环内的塌腔问题。

In order to solve the problem of quicksand in the tunnel construction of Neogene undiagenetic waterbearing sand section,according to the problems in the first seven reinforcement schemes,the treatment scheme of curtain grouting combined with surface dewatering measures was presented.According to theory and practical engineering experience,the reasonable grouting range of the first to fifth circulation curtain grouting in the 105 m section of a tunnel of Yinchuan-Lanzhou High-speed Railway was determined.The design parameters were adjusted in time according to the problems in grouting.For the problems of collapse and cavity collapse occurred in the second and fifth cycles after the completion of grouting,the corresponding solutions were given after inve stigating and analyzing the causes of the disease.The results show that:(1)The thickness of stopping rock plate is 5 m,the thickness of grouting wall is 1.5 m,the length of grouting per cycle is 25 m,and the grouting pressure is 3 to 5 MPa.(2)Too few curtain grouting holes will weaken the consolidation effect,which will lead to abnormal conditions such as landslides.(3)If the pore water in the surrounding rock is not discharged in time,the sandstone and consolidation will be softened,and the load on the pipe shed and arch will be increased if the slurry is not filled with the collapse cavity or the consolidation effect is not good;(4)The use ofϕ108 pipe shed combined withϕ42 small conduit advance support effectively solves the problem of cavity collapse in the fifth cycle.