摘要
黄土地区的地层结构大多具有上部黄土、下部泥岩的二元结构特点。隧道穿越泥岩和黄土−泥岩复合地层时,地下水重分布并易于富集于仰拱底部,泥岩遇水膨胀则会产生仰拱底鼓,而不同的地层组合及其差异性对衬砌变形及受力特性影响显著。尝试采用在仰拱底部施加位移的方式模拟泥岩膨胀作用,依托甘肃天水某隧道,开展了纯泥岩地层与交界面位于拱腰处的黄土−泥岩复合地层隧道基底均匀膨胀作用下的底鼓模型试验。分析了两种工况下衬砌内力、变形及破坏特征的差异性,并将模型试验与数值模拟结果进行了对比。结果表明:(1)模型底部加载强制位移引起的膨胀变形可分为基底土体压密阶段和基底位移等效传递阶段两个阶段。(2)由于泥岩与黄土弹性模量比值约为2:1,相较之下,交界地层中上覆黄土刚度较小,对衬砌变形约束效果弱,仰拱隆起位移更大;交界面处拱腰更易向外扩张,扩张变形达9.2 mm,约为纯泥岩地层的3倍;交界面附近衬砌截面处易产生应力集中现象。(3)在两种地层中,仰拱及拱脚位置均表现出易于产生裂缝和损坏的特性。此外,在交界地层中,衬砌拱肩部位同样显示出较高的开裂风险,并且拱脚处的裂缝有向拱腰部位扩展的趋势。(4)相较于纯泥岩地层,交界地层中交界面附近黄土对仰拱底鼓作用具有荷载释放效应,交界面处黄土压缩吸收部分底鼓作用力,因此,上覆黄土地层可延后填充层发生受拉临界破坏的时间。其研究结果可为类似交界地层隧道的理论分析、设计与施工提供参考。
Strata structure of loess area mostly features a dualistic structure of loess and mudstone.When tunnels traverse mudstone and loess-mudstone composite strata,groundwater tends to redistribute and accumulate at the base of the inverted arch.The interaction between mudstone and water causes tunnel heave,and the lithological differences between the strata significantly affect the deformation and stress characteristics of the tunnel lining.Based on a tunnel project in Tianshui City,Gansu Province,model tests were conducted on tunnel in pure mudstone and loess-mudstone composite strata with the interface at the arch waist.Displacement was applied beneath the inverted arch to simulate the swelling effect of mudstone-water interaction.Differences in internal force,deformation,and failure characteristics of the lining under two loading conditions were investigated,and numerical simulations were conducted for comparison and verification.The differences in internal force,the deformation and failure characteristics of lining under two loading conditions were investigated,and the corresponding conditions numerical simulation was conducted for comparison and verification.The results show that:(1)Expansion deformation due to forced displacement at the model’s base can be divided into two stages:the base soil compaction stage and the equivalent transfer stage of base displacement.(2)With the elastic modulus ratio of mudstone to loess approximately 2:1,the loess stratum exhibits smaller overall stiffness,resulting in larger lining deformation and even larger heave displacement in inverted arch.The arch waist at the interface is more prone to outward expansion,with an expansion deformation of 9.2 mm,about three times that of the pure mudstone stratum.Stress concentration tends to occur at the lining section near the interface.(3)In both strata,the inverted arch and arch foot positions are prone to cracking and damage.Additionally,in the composite strata,the lining arch shoulder shows a high risk of cracking,with cracks at the arch foot tending to expand towards the arch waist.(4)Compared to pure mudstone stratum,the loess near the interface in loess-mudstone strata exerts a load release effect on the heave of inverted arch.The loess at the interface compresses and absorbs some of the heave force,thereby delaying the critical tensile failure time of the filling layer.The results can provide valuable references for theoretical analysis,design and construction of tunnels in similar composite strata.
作者
梁庆国
李景
张崇辉
刘彤彤
孙志涛
LIANG Qing-guo;LI Jing;ZHANG Chong-hui;LIU Tong-tong;SUN Zhi-tao(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China;China Jikan Research Institute of Engineering Investigations and Design,Co.,Ltd.,Xi’an,Shaanxi 710000,China;China Railway First Survey and Design Institute Group Co.,Ltd.,Xi’an,Shaanxi 710043,China)
出处
《岩土力学》
北大核心
2025年第6期1811-1824,共14页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51968041)
甘肃省重点研发计划项目(No.25YFGA052)
兰州交通大学青年科学基金(No.2024032)
甘肃省优秀研究生“创新之星”(No.2025CXZX-658)
中铁一院科技项目(No.2022KY32YB-02)。
关键词
仰拱底鼓
交界地层
模型试验
数值模拟
inverted arch floor heave
interface strata
model experiment
numerical simulation
