深埋隧洞分步支护合理支护时机的力学研究  

MECHANICAL STUDY ON STEP-BY-STEP TIMELY SUPPORTING FOR DEEP-BURIED TUNNELS

作　　者：周建 胡坚 王浩[1] 杨新安[1] ZHOU Jian;HU Jian;WANG Hao;YANG Xin-an(The Key Laboratory of Road and Traffic Engineering,Ministry of Education,Tongji University,Shanghai 201804,China;Zhejiang Wenzhou Shenhai Express Way Co.Ltd.,Wenzhou,Zhejiang 325000,China)

机构地区：[1]同济大学道路与交通工程教育部重点实验室,上海201804 [2]浙江温州沈海高速公路有限公司,浙江温州325000

出　　处：《工程力学》2019年第12期145-152,共8页Engineering Mechanics

基　　金：国家自然科学基金项目(51178336);浙江省交通运输厅科研计划项目(2017038)

摘　　要：针对深埋隧洞分步支护时机缺乏可靠的理论研究,借助支护形式为“初衬+锚杆+钢拱架+二衬”的复合式衬砌结构,建立隧洞力学模型,基于Mohr-Coulomb准则,考虑开挖“空间效应”、衬砌时效特性以及支护结构分步施加的时机,推导了隧洞开挖与支护过程中塑性区应力、洞壁位移以及支护压力解析解。通过算例将该文理论成果与数值方法对比分析,验证了该方法的可行性,另外,分析了隧洞支护过程中塑性区应力、洞壁位移、支护压力的变化情况并提出隧洞分步支护的合理支护时机。研究表明:支护结构施加过程中,围岩塑性区的径向应力逐渐加强,切向应力峰区向洞壁转移,塑性区厚度大幅降低,其中,锚杆和钢拱架作用明显;优化初支施加时机后,洞壁最大位移、二衬荷载分担比较算例分别减少27.4%、13.2%,并根据优化结果给出支护结构施加时刻的建议值。研究成果对长期困扰隧道工程界支护结构如何分步支护提供了理论借鉴。Due to the lack of theoretical studies of step-by-step supporting time for deep-buried tunnels,a mechanical model was established using the composite lining structure of‘initial lining+bolt+steel arch frame+second lining’.Based on the Mohr-Coulomb criterion,the‘space effect’of excavation,the time-effect characteristics of lining and the time of step-by-step application of supporting structure were considered.The analytical expressions of the stress and deformation in the plastic zone,and the supporting pressure in the process of excavation and supporting were derived.Results from the derivation and numerical modelling were compared and the credibility of the proposed model was verified.The variation of stress in the plastic zone,displacement of the tunnel wall,supporting pressure and the supporting time were studied.Moreover,the optimal time of step-by-step supporting for tunnels were suggested.Results show that the radial stress in the plastic zone in the surrounding rocks gradually strengthened.The tangential stress of the peak area transferred to the tunnel wall and the thickness of the plastic zone decreased greatly during the installation time.Bolts and steel arches played important roles.After optimizing the time of application of the initial support,the maximum displacement of the tunnel wall and the load sharing of the secondary lining were reduced by 27.4%and 12.2%respectively.Furthermore,the optimal time for the application of supporting structures was recommended.This study is expected to provide a theoretical guidance for step-by-step supporting in tunnel engineering.

关 键 词：分步支护时机 复合式衬砌 塑性区 洞壁位移 支护压力 

分 类 号：TU457[建筑科学—岩土工程]