预制混凝土支撑对地铁竖井施工稳定性的影响
黄安平1李华龙1王招兵1任建喜2谢易2邹翔宇2
Influence of Precast Concrete Support on Metro Shaft Construction Stability
HUANG AnpingLI HualongWANG ZhaobingREN JianxiXIE YiZOU Xiangyu
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作者信息:1.中建三局集团有限公司， 430070， 武汉
2.西安科技大学建筑与土木工程学院， 710054，西安
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Affiliation:China Construction Third Engineering Bureau Co., Ltd., 430070, Wuhan, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.08.018
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中图分类号/CLCN:TU94+2;U231.3
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栏目/Col:研究报告
摘要:
目的：为了验证预制混凝土支撑的安全稳定性与优越性，需分析预制混凝土支撑对竖井施工稳定性的影响。方法：以现浇支撑支护方式为对比，针对采用预制混凝土支撑的地铁竖井，对其施工过程开展平面分析和三维数值模拟，通过分析支撑轴力，计算围护桩的沉降和水平位移变化情况，来分析预制混凝土支撑对地铁竖井施工稳定性的影响，并通过现场实测数据进行验证。结果及结论：该竖井的空间效应明显，三维模拟值与实测值更吻合。与现浇式支撑相比，采用预制混凝土支撑时的支撑轴力、围护桩水平位移更小，说明预制混凝土支撑能更好地保证竖井施工的稳定性。两种支护方式下围护桩的沉降基本一致，桩顶累计沉降值自竖井开挖后呈“台阶式”下降，平面模拟值于后期加速下降。现浇支撑一开始即受到压力的作用,预制混凝土支撑因预应力抵消作用在施工开始阶段受拉。在施工过程中，现浇式支撑的轴力大于预制混凝土支撑的轴力。根据平面模型计算结果，围护桩桩体上下端水平位移偏大。根据三维模拟结果，竖井的两侧壁能够抑制北侧桩所受的土压力及其水平位移，一至七道支撑的约束作用降低了各道支撑标高处的桩身变形。
Abstracts:
Objective: To verify the safety, stability, and advantages of precast concrete support, it is necessary to analyze its impact on shaft construction stability in metro project. Method: Compared with castinplace support mode, the metro shaft adopting precast concrete support is targeted for analysis. The construction process is analyzed in 2D and is numerical simulated in 3D. By analyzing the support axial forces and calculating the retaining pile settlement and horizontal displacement, the impact of precast concrete support on metro shaft construction stability is analyzed and verified through field measured data. Result & Conclusion: The spatial effect of the shaft is evident, and the 3D simulation results are more consistent with fieldmeasured ones. Compared to castinplace support, the precast concrete support exhibits smaller axial forces and less horizontal displacement of the retaining piles, indicating that precast concrete support can provide better stability during shaft construction. The settlement of the retaining piles is consistent for both support modes, showing a ′steplike′ decrease in cumulative settlement at pile top after excavation, with accelerated descent of the 2D simulation results in later stages. The castinplace support experiences pressure from the initial stage, while the precast concrete support is subjected to tension due to the counterprestressing action during the early stages of construction. Throughout the construction process, the axial forces in the castinplace support are greater than those in the precast concrete support. According to the 2D model simulation results, the horizontal displacement at the upper and lower ends of the retaining piles is relatively large. The 3D simulation results show that shaft walls on both sides can restrain the soil pressure and horizontal displacement on the north side piles, and the constraint action of supports 1 to 7 reduces pile deformation at different elevations.
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