含水率对粉质黏土隧道稳定性的影响机制  

Influence mechanism of water content on tunnel stability in silty clay layer

作　　者：马凯蒙 张俊儒[1] 徐剑 陈雪锋[2] 任兆丹[2] 冯冀蒙[1] MA Kaimeng;ZHANG Junru;XU Jian;CHEN Xuefeng;REN Zhaodan;FENG Jimeng(School of Civil Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China;China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan,Hubei 430063,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]中铁第四勘察设计院集团有限公司,湖北武汉430063

出　　处：《岩石力学与工程学报》2023年第3期768-779,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：高铁联合基金资助项目(U1934213)。

摘　　要：粉质黏土地层含水率变化范围大、力学性能受含水率影响大,在该地层中修建隧道含水率对隧道稳定性影响极大。基于以上背景,依托杨(柳)宣(威)高速公路大营坡隧道,开展含水率变化对粉质黏土隧道稳定性的影响研究。首先分析大营坡隧道失稳段的变形特征及其变形机制,通过三轴压缩试验得到不同含水率粉质黏土的力学参数;其次基于试验数据应用数值计算方法,研究考虑隧道周边不同区域粉质黏土含水率变化对隧道稳定性的影响机制;最终提出粉质黏土隧道失稳判别基准。研究结果表明:(1)该地区粉质黏土具有较强的水敏性,力学性能随含水率升高显著下降,含水率达到40%时,其抗剪强度与弹性模量仅为含水率15%时的10%~20%,含水率的上升造成隧道的整体沉降,大营坡隧道最大沉降量76.7 cm;(2)粉质黏土隧道稳定性随含水率变化可分为4个阶段:稳定阶段(15%~25%)、预警阶段(25%~27.5%)、报警阶段(27.5%~wcr)及失稳阶段(>wcr);(3)拱脚区域围岩含水率升高导致地基承载力不足而无法提供足够的支护抗力,是造成初期支护整体下沉、错台及严重侵限的主要原因。The water content of silty clay stratum varies widely and greatly affects the mechanical properties.The water content of silty clay stratum has great influence on tunnel stability.Thus,based on Dayingpo tunnel of YangliuXuanwei expressway,the influence of water content change on the stability of tunnels in silty clay stratum was studied.Firstly,the deformation characteristics and deformation mechanism of the unstable section of Dayingpo tunnel were analyzed.The mechanical parameters of silty clay with different water content were obtained by triaxial compression test.Secondly,based on the experimental data,the influence mechanism of silty clay water content change on tunnel stability was studied by numerical calculation method.Finally,the criterion for determining the instability of silty clay tunnel was proposed.The results show that:(1)the silty clay in this area has strong water sensitivity,and its mechanical properties deteriorate significantly with the increase of water content.When the water content reaches 40%,its shear strength and elastic modulus are only 10%–20%of that when water content is 15%.The increase of water content causes the overall settlement of the tunnel,and the maximum settlement of dayingpo tunnel is 76.7 cm.(2)According to the water content,the stability of silty clay tunnel can be divided into four stages:stable stage(15%–25%),early warning stage(25%–27.5%),alarm stage(27.5%–wcr)and unstable stage(>wcr).(3)The increase of water content of surrounding earth in the arch foot area leads to insufficient foundation bearing capacity and insufficient support resistance,which is the main reason for overall subsidence,misplacement and serious intrusion of initial support.

关 键 词：隧道工程 公路隧道 失稳机制 三轴压缩试验 粉质黏土 含水率 

分 类 号：U45[建筑科学—桥梁与隧道工程]