不良地质条件特大断面隧道支护特性研究及工程应用  

Study on Support Characteristics of Super-large Section Tunnels in Unfavorable Geological Condition and Related Engineering Application

作　　者：姚志雄 周岐窗 郑国文 吴波 范兰欣 秦浩渝 YAO Zhixiong;ZHOU Qichuang;ZHENG Guowen;WU Bo;FAN Lanxin;QIN Haoyu(Key Laboratory of Fujian Universities for Underground Engineering,Fujian University of Technology,Fuzhou 350118;Fujian Provincial Key Laboratory of Advanced Technology and Informatization in Civil Engineering,Fuzhou 350118;China Railway 24th Bureau Group Fujian Railway Construction Co.Ltd.,Fuzhou 351111;School of Civil&Architectural Engineering,East China University of Technology,Nanchang 330013)

机构地区：[1]福建理工大学地下工程福建省高校重点实验室,福州350118 [2]福建省土木工程新技术与信息化重点实验室,福州350118 [3]中铁二十四局集团福建铁路建设有限公司,福州351111 [4]东华理工大学土木与建筑工程学院,南昌330013

出　　处：《现代隧道技术》2023年第5期88-98,共11页Modern Tunnelling Technology

基　　金：国家自然科学基金(51504070);福建省自然科学基金(2021J011061);中铁二十四局集团有限公司科技项目(GY-H-22251)。

摘　　要：在软弱破碎围岩条件下施工特大断面隧道时支护不当极易造成坍塌、失稳,因此深入了解支护特性并选择合理支护参数是确保隧道稳定的关键。结合福建某典型特大断面公路隧道实际地质及环境特点,设计4种支护方案,通过数值模拟、现场试验相结合的方式深入分析单一超前支护、双层超前支护、仅双层初期支护情况下围岩、掌子面及支护结构的力学特性,探讨超前支护的作用机理,在此基础上提出合理的支护方案。结果表明,单一超前支护下(小导管或管棚)下围岩变形可减少13%~28%;双层超前支护(管棚+小导管或双层小导管)下围岩变形可减少51%~58%,支护应力状态也得到明显改善。随着超前支护强度加大,围岩变形明显降低,减小率甚至超过50%,实现“一加一大于二”的支护效果,且管棚支护效果总体略优于小导管,该结论与现场试验结果基本一致,验证了计算方法及支护方案的合理性。结合分析结果,提出了下穿高速公路段及其他围岩段的支护方案,实践证明方案是可行的,兼顾了隧道安全、支护经济性及刚度匹配性。Improper support for the construction of super-large section tunnels in weak and fractured ground is very likely to cause collapse and instability.Therefore,a thorough understanding of support characteristics and the selec⁃tion of reasonable support parameters is the key to ensuring tunnel stability.In this study,based on the actual geo⁃logical and environmental characteristics of a typical super-large section highway tunnel in Fujian province,four support schemes are designed.Through numerical simulation and on-site test,the mechanical characteristics of the surrounding rock,tunnel face and support structure under single advance support,double-layer advance support and only double-layer initial support are analyzed in depth,and the action mechanism of advance support is dis⁃cussed,and furthermore a reasonable support scheme is proposed on this basis.The results show that under a single advance support(small pipes or pipe umbrella),the deformation of the surrounding rock can be reduced by 13%to 28%.Under double-layer advance support(pipe umbrella+small pipes or double layers of small pipes),the defor⁃mation of surrounding rock can be reduced by 51%~58%,and the stress state of the support can also be significantly improved.With the increasing strength of advance support,the deformation of surrounding rock significantly de⁃creases,the reduction rate even exceeds 50%and a support effect of"1+1>2"is achieved,and the overall support effect of the pipe umbrella is slightly better than that of the small pipes.This conclusion is basically consistent with the on-site test result,verifying the rationality of the calculation method and the support plan.Based on the analysis results,a support plan for the tunnel section under-crossing the highway and other surrounding rock sections has been proposed.Practice has proven that the plan is feasible and has taken into account tunnel safety,economy of the support and rigidity matching.

关 键 词：软弱破碎围岩 特大断面隧道 双层超前支护 作用机理 刚度匹配 

分 类 号：U451[建筑科学—桥梁与隧道工程] U456[交通运输工程—道路与铁道工程]