挤压型软岩隧道大变形机理与支护参数优化研究  

Study on the Mechanism of Large Deformation and Optimization of Support Parameters in Squeezed Soft Rock Tunnels

作　　者：贺思悦 HE Siyue(China Railway First Survey and Design Institute Group Co.,Ltd.,Xi'an 710043,China)

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043

出　　处：《铁道标准设计》2024年第10期119-128,共10页Railway Standard Design

基　　金：中国国家铁路集团有限公司科技研发计划重大课题(K2020G034);中铁第一勘察设计院集团有限公司科研开发课题(16-20,17-15)。

摘　　要：地应力水平是隧道挤压型软岩大变形主导因素之一,深部地应力与岩体力学特性对隧道设计具有较强参考价值。以西成铁路甘青隧道地应力测试与岩体力学试验为基础,深入分析测试数据,采用数值模拟方法进行不同地应力水平的计算,对比现场实测数据,结果发现,测区地应力以水平地应力为主导,三向地应力关系为S_(H)>S_(h)>S_(V),具有较强的水平构造作用,地应力比值在1.5~4.5之间,随着埋深增加逐渐减小;岩体荷载-变形(P-W)曲线外包络线形态大体上呈现为“下凹形”,以塑性变形为主;仅有少量弹性变形,岩体抗剪断应力-应变(τ-ε)曲线基本呈抛物线形,屈服值不明显,以塑性破坏为主。随着地应力比值增加,隧道水平变形越来越大,竖直变形先减小后增加,二者比值介于0.70~2.45之间,均小于地应力比值,最大变形由拱顶向拱腰转移,围岩主应力差值逐渐增加,挤压形变压力越来越大。在此基础上,针对甘青隧道进口的水平挤压大变形特征,提出增大拱架刚度、加强锁脚、加强拱架纵向连接、增大隧道预留变形量等支护优化措施,现场实测表明,这些措施有效控制了隧道变形。The level of in-situ stress is one of the dominant factors in large deformation of tunnels in squeezed soft rock.Deep in-situ stress and mechanical properties of rock mass provide a valuable reference for tunnel design.Based on in-situ stress tests and rock mass mechanical experiments in the Ganqing Tunnel of the Xining-Chengdu Railway,a detailed analysis of the test data was conducted.Numerical simulation methods were employed to calculate different levels of in-situ stress,and the results were compared with field measurements.The results showed that the in-situ stress in the study area was primarily dominated by horizontal stress,with the three-dimensional in-situ stress relationship being S_(H)>S_(h)>S_(V),indicating strong horizontal tectonic forces.The in-situ stress ratio ranged between 1.5 and 4.5,decreasing gradually with increasing tunnel depth.The outer envelope of rock mass load-deformation curve(P-W)generally exhibited a“concave”shape,mainly characterized by plastic deformation with only a small amount of elastic deformation.The rock shear stress-strain curve(τ-ε)primarily exhibited a“parabolic”shape with no distinct yield point,mainly reflecting plastic failure.As the ratio of in-situ stress increased,the horizontal deformation of the tunnel grew,while the vertical deformation decreased initially and then increased,with the ratio of the two falling between 0.70 and 2.45,both of which were smaller than the in-situ stress ratio.The maximum deformation shifted from the vault to the arch waist,while the principal stress difference in the surrounding rock gradually increased,resulting in greater squeezing deformation pressure.Based on these findings,support optimization measures were proposed for the large horizontal squeezing deformation at the entrance of the Ganqing Tunnel,including increasing the stiffness of the arch frame,strengthening the foot locking,enhancing the longitudinal connection of the arch frame,and increasing the reserved tunnel deformation.Field measurements indicated that th

关 键 词：铁路隧道 挤压型软岩大变形 地应力测试 岩体力学特性 变形控制 参数优化 

分 类 号：U25[交通运输工程—道路与铁道工程]