某新近系富水砂岩铁路隧道涌砂灾害成因及处理措施分析  

Analysis on the Cause and Treatment of Sand Gushing Disaster in a Neogene Water-rich Sandstone Railway Tunnel

作　　者：马彦军 吴红刚 赵彦君 丁鸿程 杨学虎 MA Yanjun;WU Honggang;ZHAO Yanjun;DING Hongcheng;YANG Xuehu(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Northwest Research Institute Co.,Ltd.of CREC,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070 [2]中铁西北科学研究院有限公司,兰州730070

出　　处：《铁道标准设计》2025年第2期136-143,175,共9页Railway Standard Design

基　　金：国家重点研发计划项目(2018YFC1504901);中国中铁科学研究院有限公司科研项目((科研)字2017-KJ008-Z008-XB);中铁北京工程局集团有限公司中兰铁路项目(ZLZQ-2-QT-(2021)-026)。

摘　　要：新近系砂岩主要为粉细粒结构,泥质弱胶结,在干燥状态下较坚硬,但浸水极易软化崩解,软化系数小,成岩性差,在该类地层中开挖隧道易发生涌砂灾害。为探究新近系富水砂岩地层中隧道建设出现涌砂灾害的原因并制定处理措施,以中兰铁路香山隧道为依托,通过现场施工监测,对涌砂土体取样,从粒径组成、含水率以及力学等方面进行分析。多次调整支护措施依旧未能解决涌砂问题后,隧道被确定为VI级围岩,最终采用地表降水结合帷幕注浆进行围岩加固。研究发现,涌砂灾害的发生以高细砂含量为基础,0.5 mm以下颗粒占比为92%,在流固耦合作用下,地下水渗透作用加强,导致围岩软化,土体抗剪强度降低,最终出现涌砂灾害;隧道砂岩含水率为9%时将出现涌砂现象,含水率达到17%时产生较大规模涌砂涌水灾害;洞内真空降水未能达到预期,采用地表降水结合帷幕注浆进行围岩加固后,含水率从26%降低到12%左右,施工速度提升4倍;监测发现,隧道变形在27d左右趋于稳定,拱顶沉降52 mm,收敛值为62.5 mm。建议在新近系富水砂岩中开挖隧道时,采用地表降水措施结合帷幕注浆进行加固,降低岩层含水率到9%以下,同时通过超前地质勘探动态调整帷幕注浆施工参数。Neogene sandstone is mainly a fine-grained structure,argillaceous weak cementation and relatively hard in the dry state,but it tends to get soften and collapse when submerged in water with small softening coefficient and poor lithology.When tunneling in this kind of stratum,sand burst is likely to occur.To explore the causes of sand bursting disaster in Neogene water-rich sandstone formation and develop treatment measures,the Xiangshan Tunnel of the Yinchuan-Lanzhou High-speed Railway is taken as an example.Through site construction monitoring,the sand body was sampled and analyzed from the aspects of particle size composition,moisture content,and mechanics.After several adjustments to support measures,it was failed to solve the sand bursting problem,the tunnel was identified as Grade VI surrounding rock,and finally,the surface precipitation combined with curtain grouting was used for surrounding rock reinforcement.It is found that the occurrence of sand bursting disasters is based on the content of the fine sand composition,and the proportion of particles below 0.5 mm is 92%.Under the interaction of fluid-structure,the permeability of groundwater is strengthened,which leads to the softening of surrounding rock and the decrease of shear strength of soil,and the sand bursting disaster finally occurs.Sand gushing occurs when the moisture content of sandstone is 9%,and large-scale sand gushing occurs when the moisture content reaches 17%.Vacuum precipitation in the cave failed to meet expectations.After surface precipitation combined with curtain grouting for surrounding rock reinforcement,the moisture content decreased from 26%to about 12%,and the construction speed increased by 4 times.The monitoring results showed that the tunnel deformation tended to be stable at about 27 days,the arch settlement was 52 mm,and the convergence value was 62.5 mm.It is suggested that while excavating tunnels in Neogene water-rich sandstone,surface precipitation measures should be adopted in combination with curtain grouting method

关 键 词：铁路隧道 新近系砂岩 涌砂机理 地表降水 帷幕注浆 

分 类 号：U25[交通运输工程—道路与铁道工程] U459.1[建筑科学—桥梁与隧道工程]