地铁工程先盾后扩穿越西安地裂缝设防段隧道扩挖方案研究  

Tunnel Expansion Excavation Scheme for Metro Engineering with STFE through Xi’an Ground Fissure Control Section

作　　者：杨万精 高强 YANG Wanjing;GAO Qiang(Xi’an Construction Engineering Quality and Safety Supervision Station,710061,Xi’an,China;不详)

机构地区：[1]西安市建设工程质量安全监督站,西安710061 [2]广州地铁设计研究院股份有限公司,广州510010

出　　处：《城市轨道交通研究》2023年第9期138-142,共5页Urban Mass Transit

基　　金：西安市轨道交通集团有限公司科技项目(D15-YJ-152021006);广州地铁设计研究院股份有限公司科技项目(KY-2020-003)。

摘　　要：目的:为优化地铁工程穿越西安地裂缝段常规“竖井暗挖+盾构空推”施工方法,开展基于“先盾后扩”新型建造技术的扩挖方案研究。方法:依托西安地铁15号线府君庙村站—祝村站区间隧道穿越F9和F′9两条地裂缝带设防工程,进行新型建造技术试点应用。介绍了“先盾后扩”法的施工基本流程和设计要点,提出了6种设防段盾构扩挖方案,重点讨论了各方案可行性及优缺点,并综合施工便利性、地面沉降控制和结构受力特性给出了推荐方案。结果及结论:“先盾后扩”法省去了竖井和洞内端头土体加固工程量,确保了盾构作业连续性,解决了设防段地面作业条件受限的问题,不考虑盾构空推的扩挖断面也可大幅减小,进而降低了工程造价;设防段盾构扩挖时,横向及竖向支撑能改善扩挖隧道支护结构变形,但临时仰拱或横撑发挥的作用较为有限,在地层降水措施有保障的条件下设置的必要性不强;竖撑能明显改善扩挖隧道支护结构受力,应予以保留;综合横向及竖向支撑切割断面引起的施工干扰问题,推荐“全断面+双竖撑法扩挖”为依托工程扩挖方案。Objective:To optimize the conventional construction method of′vertical shaft underground excavation+shield tunneling with forward thrust′for metro engineering crossing ground fissure sections in Xi’an,an excavation scheme based on the new construction technique of′shield tunneling followed by expansion′(abbreviated as STFE)is studied.Method:Based on the protection and control project of Xi’an Metro Line 15 Fujunmiaocun Sta.to Zhucun Sta.(Fu-Zhu)interval tunnel that crosses F9 and F′9 two ground fissure belts,a pilot application of the new construction technique is conducted.The basic process and design principles of the STFE method are introduced.Six shield tunnel expansion excavation schemes for the control section are proposed by focusing on the feasibility,advantages and disadvantages of each scheme.Taking into account construction convenience,land subsidence control,and structural stress behavior,a recommended scheme is presented.Result&Conclusion:The STFE method eliminates the amount of vertical shafts and the reinforcement soil mass at tunnel ends,ensuring continuous shield tunneling operation,and solving the problem of limited ground operation conditions in control sections.Thus,the expansion excavation cross-section can be significantly reduced without considering forward thrust,thereby reducing engineering costs.During shield tunnel expansion excavation in the control sections,lateral and vertical supports can improve tunnel support structure deformation.However,the role of temporary invert arches or horizontal struts is relatively limited,and it is not substantial for setting under the conditions of guaranteed ground dewatering measures.Vertical struts can significantly improve the stress conditions of the expansion excavated tunnel supporting structure and should be retained.Considering the construction disturbance problems caused by cutting sections with lateral and vertical support,the′full-section+double vertical struts expansion excavation′is recommended for the project.

关 键 词：地铁隧道 西安地裂缝 先盾后扩 扩挖方案 

分 类 号：U455.4[建筑科学—桥梁与隧道工程]