铁路隧道疑难工程地质问题分析——以30多座典型隧道工程为例

Analysis of Geological Problems of Railway Tunnels:Case Study of Typical Tunnels

以30多座在施工中发生与地质因素有关的工程事件为例,归纳为15类疑难工程地质问题:高压富水岩溶、软弱围岩大变形、太古界硬质变质岩大变形、侵入岩脉蚀变风化破碎岩体塌方和突泥、富水逆掩断层破碎带大规模突泥、层状地层大规模顺层塌方、中更新统老黄土崩塌、新第三系地层突泥涌砂、泥岩页岩可燃气体燃烧和爆炸、白云岩剪涨裂缝突砂涌砂、岩溶地面沉降、含石膏地层围岩变形、断层破碎带与软岩层面组合围岩变形、新第三系粉质黏土岩(土)垂直节理坍塌变形及石英砂岩断层破碎带突水涌砂。分析各类疑难工程地质问题发生的原因,总结其工程地质特征。针对高压富水岩溶的分类、断层破碎带突水涌砂和大变形问题、高压地下水的防治、高位选线、大变形及大变形分级标准、挤压大变形和卸荷大变形、隧道顺层偏压构造的危害、5种围岩变形失稳类型的特征对比、隧道围岩压力现场实测、岩溶地面塌陷、Q2老黄土和N2黏土层垂直节理渗水崩塌、N2弱胶结地层"流变"、石膏地层隧道衬砌开裂以及非煤系地层的可燃气等14类问题进行讨论,并从依法合规性、地质不确定性、专项地质工作、工程劣质岩、修订围岩分级和纳入规范等方面提出6条建议。

Fifteen kinds of engineering geological problems,i. e. high-pressure water-rich karst,large deformation of soft rock,large deformation of archaean metamorphic hard rock,collapse and mud burst of alteration and weathered broken rock,large scale mud burst from fracture zone,large scale collapse of layered strata,collapse of mid-pleistocene series old loess,mud and sand inrush from neogene system strata,combustion and explosion of combustible gas in mud rock and shale,sand gushing of shear cracks in dolomite,ground settlement of karst,surrounding rock deformation of anhydrite strata,surrounding rock deformation induced by the interaction of fault fracture zone and soft rock,deformation and collapse induced by vertical joints of neogene system silty clay,and water and sand gushing from fault fracture zone in quartz sandstone,are analyzed by taking more than 30 typical tunnels for examples. The causes and characteristics of the mentioned geological problems are analyzed. Discussion are made on 14 kinds of problems,i. e. classification of high-pressure water-rich karst,water and sand inrush and large deformation of fault fracture zone,countermeasures for high pressure groundwater,line selection,code for large deformation and its classification,squeezing and unloading large deformation,unsymmetrically loaded tunnel,comparison among 5 kinds of surrounding rock instability,field measurement of tunnel surrounding rock pressure,ground collapse of karst,collapse induced by seepage from vertical joint of Q2 old loess and N2 clay,rheology of weakly consolidated N2 strata,lining cracks of tunnel in anhydrite strata and combustible gas from non-coal strata. Six suggestions have been given in terms of construction legality,geological uncertainty,special geology work,bad rocks,revision of surrounding rock classification and code collection.