叠合拱-墙法大跨暗挖地铁隧道建造关键技术研究
胡奇凡1朱占国1郭家兴1孙宇1赵斌1熊春林2陈晓斌2
Key Technologies for Large-span Mined Metro Tunnel Construction Using Superimposed Arch-wall Method
HU Qifan1ZHU Zhanguo1GUO Jiaxing1SUN Yu1ZHAO Bin1XIONG Chunlin2CHEN Xiaobin2
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作者信息:1.中国铁路设计集团有限公司， 300251， 天津
2.中南大学土木工程学院， 410075， 长沙
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Affiliation:1.China Railway Design Corporation, 300251, Tianjin, China
2.School of Civil Engineering, Central South University, 410075, Changsha, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.20241154
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中图分类号/CLCN:U455.7
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栏目/Col:土建工程
摘要:
［目的］采用中隔壁、双侧壁导坑等分部开挖工法开挖大跨暗挖地铁隧道时，受临时支撑影响，大型机械化作业难以有效实施。为适应环境敏感场地微振机械化施工要求，需研发SAWS（叠合拱-墙）法大跨暗挖隧道开挖支护方法，并对其关键技术进行研究。［方法］在简述了SAWS（叠合拱-墙）法技术之后,以重庆某软岩地层单拱大跨暗挖地铁车站为例，采用FLAC 三维软件建立数值模型，对车站开挖全过程中地层、结构力学行为进行了模拟仿真，对比分析了工法1（常规双侧壁导坑法）和工法2（SAWS）法在地面沉降、围岩塑性区分布、初支结构变形、初支结构应力、锚杆轴力等方面的差异，验证了SAWS法的适用性及可靠性。［结果及结论］对比双侧壁导坑法，采用SAWS法后，地面最大沉降增加约12.4%，拱顶最大沉降增加约8.5%，洞内沿垂直隧道线路方向的最大水平位移增加约26.0%，且各项变形均具有足够的安全冗余度；初支拱脚内力减小约42.9%，侧墙中下部系统锚杆轴力降低约20.0%~30.0%。2种工法的拱底隆起及围岩塑性区分布基本一致。SAWS法具有足够的安全性，初支及锚杆结构受力合理。SAWS法可以满足大型机械化施工需要，具备可实施性。
Abstracts:
［Objective］ When using sequential excavation methods such as central diaphragm walls and double-side heading techniques to construct large-span mined metro tunnels, temporary supports often hinder the effective use of large-scale mechanized operations. To meet the requirements of low-vibration mechanized construction in environmentally sensitive areas, it is necessary to develop the SAWS (superimposed arch wall system) method for large-span mined tunnel excavation and support, and to study its key technologies. ［Method］ After a brief introduction of SAWS (superimposed arch-wall support) method, taking a large-span single-arch mined metro station in Chongqing soft rock formation as an example, a numerical model is established using FLAC 3D software to simulate and analyze the geotechnical and structural mechanical behaviors during the entire station excavation process. A comparative analysis is conducted between Method 1 (conventional double-side heading method) and Method 2 (SAWS method) in terms of land subsidence, distribution of plastic zones in surrounding rock, deformation of initial support structure, stress in initial support structure, and axial force in system anchors, in order to verify the applicability and reliability of SAWS method. ［Result & Conclusion］ Compared to the double-side heading method, the SAWS method results in a maximum land subsidence increase of approximately 12.4%, in a maximum arch vault settlement of 8.5%, and 26.0% in maximum horizontal convergence within the tunnel along the direction perpendicular to tunnel line, all of which remain within safe margins. The internal force at the arch foot of the initial support is reduced by about 42.9%, and the axial force of system anchors in side wall middle and lower parts decreases by approximately 20.0% to 30.0%. The arch invert heave and the distribution of plastic zones in surrounding rock are essentially the same for both methods. SAWS method demonstrates sufficient safety and reasonable stress distribution in the initial support and anchoring structures. It can meet the requirements for large-scale mechanized construction and is feasible for implementation.
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