浅埋偏压隧道洞口段超前大管棚支护效果分析  

Analysis on the Support Effect of Advance Large Pipe Umbrella at Portal Section of Shallow Tunnel under Unsymmetrical Load

作　　者：宋战平[1,2,3] 裴佳锋 潘红伟 孙泽 丁立波 SONG Zhanping;PEI Jiafeng;PAN Hongwei;SUN Ze;DING Libo(School of Civil Engineering of Xi′an University of Architecture and Technology,Xi′an 710055;Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering,Xi′an 710055;Tunnel and Underground Structure Engineering Research Institute of Xi′an University of Architecture and Technology,Xi′an 710055;The First Engineering Co.,Ltd.of China Railway Beijing Engineering Group,Xi′an 710100;China Road&Bridge Corporation,Beijing 100011)

机构地区：[1]西安建筑科技大学土木工程学院,西安710055 [2]陕西省岩土与地下空间工程重点实验室,西安710055 [3]西安建筑科技大学隧道与地下结构工程研究所,西安710055 [4]中铁北京工程局集团第一工程有限公司,西安710100 [5]中国路桥工程有限责任公司,北京100011

出　　处：《现代隧道技术》2022年第6期86-96,共11页Modern Tunnelling Technology

基　　金：陕西省创新能力支撑计划-创新团队(2020TD-005);陕西省住房城乡建设科技计划(2019-K39).

摘　　要：浅埋偏压隧道洞口段的合理支护措施是实现隧道洞口安全施工的关键,洞口段往往会遇到浅埋偏压、山体表层岩石强风化以及围岩软弱破碎等不良地质,需采用超前支护措施来控制围岩变形。以在建的格鲁吉亚E60高速公路F3标段4号隧道第比利斯端洞口工程为背景,采用数值试验方法,对比分析了洞口新意法开挖时有无超前管棚支护对隧道洞口段的地表沉降、掌子面挤出变形、预收敛变形、收敛变形、围岩应力分布及塑性区的发展的影响。基于数值试验结果的分析表明:采用新意法施工,隧道洞口段的超前管棚支护可以促进应力拱的形成,改善了超前核心土的受力,减小了掌子面的挤出变形和核心土的塑性区范围;在掌子面前后约1倍洞径的范围内,隧道拱顶沉降的速率最大,变形量达到总变形量的85%;同时,超前管棚支护将极大地减小围岩的塑性区范围,避免了浅埋洞口段围岩塑性区发展至地表而导致的洞口整体坍塌。The reasonable support measures for the portal section of shallow tunnel under asymmetric load are the key to achieving the safe construction of the tunnel portal. The portal section often encounters unfavorable geology such as shallow asymmetric load, strong weathering of mountain surface rock, and soft and broken surrounding rock,so it is necessary to use advance support measures to control the deformation of surrounding rock. The Tbilisi portal project of No. 4 tunnel of Lot F3 of E60 expressway in Georgia under construction is taken as the case to analyze the influence of the ADECO-RS excavation method with or without advance pipe-umbrella support on the ground settlement, extrusion deformation of tunnel face, pre-convergence deformation, convergence deformation, stress distribution of surrounding rock and the development of plastic zone of tunnel portal section by means of the numerical test method. The analysis based on the numerical test results shows that the advance pipe-umbrella support at the tunnel portal section can promote the formation of stress arch, improve the stress of the advance core soil, reduce the extrusion deformation of the tunnel face and the plastic zone range of core soil when the ADECO-RS method is used for construction. In the range of about one time tunnel diameter in front of and behind the tunnel face, the tunnel crown settlement rate is the largest, and the deformation amount reaches 85% of the total amount. At the same time,the advance pipe-umbrella support will greatly reduce the plastic zone range of surrounding rock and avoid the overall collapse of the tunnel portal caused by the plastic zone of surrounding rock in the shallow tunnel portal section developing to the surface.

关 键 词：隧道工程 超前大管棚 新意法 数值模拟 稳定特性 

分 类 号：U455.7[建筑科学—桥梁与隧道工程]