摘要
为有效控制软散围岩隧道变形,结合软散围岩特性和施工工艺,分析了软散围岩隧道荷载来源,确定了软散围岩隧道大变形控制原则,提出了“加强初期支护拱脚约束,同时增设拱部额外约束”的隧道变形控制思路;建立了考虑局部约束补强的初期支护结构力学分析模型,结合算例分析了增设拱部额外约束对改善初期支护结构内力的作用效应,探讨了不同荷载模式下拱部额外约束的最佳布设位置;依托典型工程,研究了采用初期支护局部约束补强控制软散围岩隧道变形的施工工艺及支护效果。结果表明:隧道分部开挖施工中初期支护难以做到及时密贴围岩并提供足够的支护刚度,这是诱发离散型大变形的重要原因;在初期支护拱部增设额外约束,可以有效减小初期支护危险截面弯矩和轴力,同时有利于减小拱脚地基的应力集中和竖向位移;围岩压力以垂直荷载为主时,拱部额外约束宜设在拱顶附近,以拱顶两侧10°范围内为最佳;围岩压力以水平荷载为主时,拱部额外约束宜靠近上台阶两侧拱脚(偏离拱顶40°以外)或中台阶两侧边墙位置;采用增设“拱部小孔径锚索+拱脚大管径注浆锁脚锚管”的成套施工方法及工艺,能够有效控制软散围岩隧道变形;研究成果对抑制软散围岩隧道离散变形具有重要指导意义。
In order to effectively control the deformation of tunnels with soft and loose surrounding rock,combined with the characteristics and construction technology of soft and loose surrounding rock,the load sources of tunnels with soft and loose surrounding rock were analyzed,and the control principles for large deformation of tunnels with soft and loose surrounding rock were determined.The tunnel deformation control idea of“strengthening the initial support arch foot constraint and adding additional arch constraints”was proposed.A mechanical analysis model for the initial support structure incorporating local constraint reinforcement was established.Using a case study,the effect of adding arch constraints on improving the internal forces of the initial support structure was analyzed,and the optimal installation positions for these additional arch constraints under different load patterns were investigated.Based on a typical project,the construction techniques and support effectiveness of using locally reinforced constraints in the initial support to control deformation of soft and loose rock tunnels were studied.The results indicate that the inability of the initial support to be timely installed,achieve tight contact with the surrounding rock,and provide sufficient support stiffness during partial tunnel excavation is a significant cause of discrete deformation.Adding additional constraints to the arch of the initial support can effectively reduce the bending moments and axial forces at critical sections,while also mitigate stress concentration and vertical displacement at the foot foundations.When the surrounding rock pressure is predominantly vertical,the additional arch constraints should be installed near the arch crown,optimally within 10°on both sides of the crown.When horizontal pressure dominates,the constraints should be installed near the arch feet on both sides of the upper bench(beyond 40°from the crown)or on the sidewalls of the middle bench.The integrated construction method and technique involving“small-diameter anchor cables in the arch+large-diameter grouted feet-lock pipes”effectively controls the deformation of soft and loose rock tunnels.The study results have important guiding significance for suppressing the discrete deformation of soft and loose rock tunnels.
作者
陈丽俊
陈建勋
翟阳
王智佼
张立鑫
罗彦斌
CHEN Lijun;CHEN Jianxun;ZHAI Yang;WANG Zhijiao;ZHANG Lixin;LUO Yanbin(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;Gansu Changda Highway Co.,Ltd.,Lanzhou 730030,Gansu,China)
出处
《建筑科学与工程学报》
北大核心
2025年第5期155-170,共16页
Journal of Architecture and Civil Engineering
基金
国家重点研发计划项目(2024YFB2606100)
国家自然科学基金重点项目(41831286)。
关键词
隧道工程
软散围岩
初期支护
变形控制
小孔径锚索
tunnel engineering
soft and loose rock
initial support
deformation control
small-diameter anchor cable
作者简介
陈丽俊(1986-),男,工学博士,副教授,E-mail:chenlijun2004@126.com;通信作者:陈建勋(1969-),男,工学博士,教授,博士生导师,E-mail:chenjx1969@chd.edu.cn。
