浅埋顺层偏压洞口边坡失稳机制及防治研究  

Study on Mechanism and Prevention of Slope Instability at Shallow-buried,Bedding and Unsymmetrically Loaded Tunnel Portal

作　　者：赵海松 魏安辉 邵江 向波 邬凯 李世琦 周仁强 柳松 ZHAO Haisong;WEI Anhui;SHAO Jiang;XIANG Bo;WU Kai;LI Shiqi;ZHOU Renqiang;LIU Song(Sichuan Highway Planning,Survey,Design and Research Institute Co.,Ltd.,Chengdu 610041)

机构地区：[1]四川省公路规划勘察设计研究院有限公司,成都610041

出　　处：《现代隧道技术》2024年第3期253-265,289,共14页Modern Tunnelling Technology

基　　金：四川省交通运输科技项目(No.2021-A-12、No.2021-A-02);四川省公路规划勘察设计研究院有限公司自立项目(2022-YL-02)。

摘　　要：充分认识顺层偏压洞口边坡失稳演化机制,研究边坡支挡结构受力和隧道埋深的关系,是洞口边坡防护的关键。石梁子隧道施工期间,浅埋顺层偏压洞口发生边坡失稳破坏,采用地质调绘及钻孔、地表位移监测、数值模拟等方法,在查明坡体结构、物理力学参数及变形特征的基础上,分析洞口边坡失稳机制,对顺层偏压洞口边坡防护方法及措施进行研究。结果表明,浅埋顺层偏压洞口边坡失稳演化经历4个阶段,依次为层间抗剪强度降低阶段→顺层偏压形成阶段→下部局部破坏,牵引后方坡体蠕滑拉裂阶段→变形加剧,洞口边坡发生推移式破坏阶段;设置抗滑桩+靠山侧隧道埋深16 m情况下坡体稳定,此时对滑坡体变形及桩身剪力的控制效果显著,当埋深大于16 m后效果增幅明显变差。Understanding the evolution mechanism of slope instability at the bedding and unsymmetrically loaded tunnel portal and studying the relationship between slope retaining structure stress and tunnel burial depth is crucial for slope protection.During the construction of the Shiliangzi Tunnel,the slope instability and failure occurred at the shallow-buried,bedding and unsymmetrically loaded tunnel portal.Geological mapping,borehole drilling,surface displacement monitoring,numerical simulation,and other methods were used to clarify the slope structure,physical-mechanical parameters,and deformation characteristics.Based on this,the instability mechanism of the slope at the tunnel portal was analyzed,the protection methods and measures for the slope at the bedding and unsymmetrically loaded tunnel portal were studied.Results show that the instability evolution of the slope at the shallow buried,bedding and unsymmetrically loaded tunnel portal goes through four stages:1)reduction of interlayer shear strength,2)formation of bedding and unsymmetrical loading,3)local failure of lower slope body leading to retrogressive creep and cracking of back slope,4)exacerbation of deformation leading to thrust load-caused failure of the slope at the tunnel portal.With the installation of anti-slide piles and a tunnel burial depth of 16 m on the mountain side,the slope stability is achieved.At this depth,control over landslide deformation and pile shear force is significant.However,the effectiveness decreases significantly when the burial depth exceeds 16 m.

关 键 词：顺层偏压 洞口边坡 变形特征 失稳机制 数值模拟 防治 

分 类 号：U452[建筑科学—桥梁与隧道工程]