Design of triple-row pile foundation pit support combined with CFG piles under shallow to deep process
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摘要: 北京地区某建筑项目高层住宅楼与纯地下车库毗邻,二者基础高差7.6 m,根据施工进度安排,位于浅部的住宅楼需先于车库施工,毗邻段车库基坑支护设计需考虑最不利工况,即住宅结构封顶时车库基坑肥槽尚未回填。为有效控制深部基坑与浅部住宅楼变形,对深部基坑采用结合浅部住宅楼CFG桩的三排桩支护方案。数值模拟和基坑变形监测表明,深部基坑变形和浅部住宅沉降及倾斜均处于可控范围,浅部住宅楼荷载绝大部分通过CFG桩传递至深部地层中,对深部基坑影响较小。本方案中CFG桩兼作竖向承载和水平承载构件,可采用扩径和配筋相结合的措施增加其侧向刚度,同时需要注意控制复合地基承载力和刚度的均匀性。Abstract: In a construction project in Beijing, a high-rise residential building is adjacent to an underground garage, with a foundation height difference of 7.6 m. According to the construction schedule, the shallow residential building must be completed before the garage excavation. The design of the garage’s foundation pit support must consider the most critical scenario: the residential structure is topped out while the backfill space of the garage pit remains unfilled. To effectively control deformation in the deep foundation pit and the shallow residential building, a triple-row pile support system is adopted, integrating the adjacent CFG piles of the residential building. Numerical simulations and field monitoring demonstrate that deformations in the deep pit, settlement, and inclination of the residential building are within controllable limits. The load from the residential building is primarily transferred to deeper strata via the CFG piles, exerting minimal impact on the deep excavation. In this scheme, CFG piles serve dual functions: vertical load-bearing and lateral resistance. Their lateral stiffness is enhanced through a combination of diameter expansion and reinforcement. Additionally, uniformity in the bearing capacity and stiffness of the composite foundation must be rigorously controlled.
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Key words:
- shallow to deep /
- CFG pile /
- triple-row pile /
- prediction of deformation /
- deformation monitoring
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表 1 各土层主要物理力学参数
Table 1. Main physical and mechanical parameters of each soil layer
地层岩性 γ/(kN·m−3) Es1-2/MPa c/kPa φ/(°) ②黏质粉土–砂质粉土 19.9 11.4 20 26.7 ③粉质黏土–黏质粉土 19.5 6.1 25 10.4 ④粉质黏土–黏质粉土 19.9 6.9 22 16.7 ⑤粉质黏土–黏质粉土 19.8 8.5 25 20 ⑤2细砂 20 30 0 25 ⑥全风化–强风化泥岩 21 7.2 35 30 ⑦强风化–中等风化泥岩 22 50 40 35 ⑧中等风化泥岩 23.7 80 70 60 表 2 结构单元参数
Table 2. Structural element parameters
构件类别 材料 弹性模量
E/MPa重度γ
/(kN·m−3)外径
D/m厚度
h/m截面尺寸
B×H
/(m×m)钢筋桩 C25钢筋混凝土 28 000 25.0 0.6 CFG桩 C25素混凝土 28 000 23.0 0.4 挡土板 C20钢筋混凝土 21 500 24.0 0.1 冠梁及连梁 C25钢筋混凝土 28 000 25.0 0.7×0.5 -
[1] 刘国斌, 王卫东. 基坑工程手册[M]. 2版. 北京: 中国建筑工业出版社, 2009. (LIU G B, WANG W D. Excavation engineering manual[M]. 2nd ed. Beijing: China Architecture & Building Press, 2009. (in Chinese)LIU G B, WANG W D. Excavation engineering manual[M]. 2nd ed. Beijing: China Architecture & Building Press, 2009. (in Chinese) [2] 赵升峰, 黄广龙, 范钦建, 等. 先浅后深深基坑围护设计与分析[J]. 建筑结构, 2013, 43(11): 88-91. (ZHAO S F, HUANG G L, FAN Q J, et al. Design and analysis on deep foundation pit support with shallow to deep construction[J]. Building Structure, 2013, 43(11): 88-91. (in Chinese)ZHAO S F, HUANG G L, FAN Q J, et al. Design and analysis on deep foundation pit support with shallow to deep construction[J]. Building Structure, 2013, 43(11): 88-91. (in Chinese) [3] 周亚丽, 金雪莲, 竺明星. 先浅后深深基坑工程的设计与分析[J]. 建筑结构, 2020, 50(23): 123-127,17. (ZHOU Y L, JIN X L, ZHU M X. Design and analysis of the deep foundation pit project constructed from shallow to deep[J]. Building Structure, 2020, 50(23): 123-127,17. (in Chinese)ZHOU Y L, JIN X L, ZHU M X. Design and analysis of the deep foundation pit project constructed from shallow to deep[J]. Building Structure, 2020, 50(23): 123-127,17. (in Chinese) [4] 陈 娟, 唐德康. 软土区域先浅后深基坑工程围护设计与应用[J]. 中国市政工程, 2021(3): 80-83. (CHEN J, TANG D K. Design & application of shallow first & deep foundation pit support in soft soil area[J]. China Municipal Engineering, 2021(3): 80-83. (in Chinese) doi: 10.3969/j.issn.1004-4655.2021.03.022CHEN J, TANG D K. Design & application of shallow first & deep foundation pit support in soft soil area[J]. China Municipal Engineering, 2021(3): 80-83. (in Chinese) doi: 10.3969/j.issn.1004-4655.2021.03.022 [5] 张学伟, 夏志锋, 李学虎, 等. 紧邻地铁隧道群基坑先浅后深施工技术[J]. 施工技术, 2014, 43(21): 63-66. (ZHANG X W, XIA Z F, LI X H, et al. Construction technology of shallow to deep foundation excavation close to the subway tunnel[J]. Construction Technology, 2014, 43(21): 63-66. (in Chinese)ZHANG X W, XIA Z F, LI X H, et al. Construction technology of shallow to deep foundation excavation close to the subway tunnel[J]. Construction Technology, 2014, 43(21): 63-66. (in Chinese) [6] 潘伟强. 共用围护相邻基坑“先浅后深”施工技术[J]. 地下工程与隧道, 2013(4): 27-31,59-60. (PAN W Q. Construction technology of “The shallow first and then deep” for adjacent excavation pits Sharing retaining wall[J]. Underground Engineering and Tunnels, 2013(4): 27-31,59-60. (in Chinese)PAN W Q. Construction technology of “The shallow first and then deep” for adjacent excavation pits Sharing retaining wall[J]. Underground Engineering and Tunnels, 2013(4): 27-31,59-60. (in Chinese) [7] 杨文平, 张少青, 蒋永丰. 共用基坑围护体系先浅后深施工技术[J]. 施工技术(中英文), 2023, 52(7): 81-85. (YANG W P, ZHANG S Q, JIANG Y F. Shallow first and then deep construction technology of shared foundation excavation enclosure system[J]. Construction Technology, 2023, 52(7): 81-85. (in Chinese)YANG W P, ZHANG S Q, JIANG Y F. Shallow first and then deep construction technology of shared foundation excavation enclosure system[J]. Construction Technology, 2023, 52(7): 81-85. (in Chinese) [8] 张 欢. 三排桩支护体系在深基坑开挖中的变形与内力研究[D]. 宜昌: 三峡大学, 2019. (ZHANG H. Study on deformation and internal force of three-row piles supporting system in deep foundation pit excavation[D]. Yichang: China Three Gorges University, 2019. (in Chinese)ZHANG H. Study on deformation and internal force of three-row piles supporting system in deep foundation pit excavation[D]. Yichang: China Three Gorges University, 2019. (in Chinese) [9] 董必昌, 王雅新, 陈世龙, 等. 深基坑三排桩支护结构被动区力学特性研究[J]. 武汉理工大学学报(交通科学与工程版), 2024, 48(2): 347-352. (DONG B C, WANG Y X, CHEN S L, et al. Research on mechanical properties of passive earth pressure of treble-row-piles wall retaining and protection structure for deep excavations[J]. Journal of Wuhan University of Technology (Transportation Science & Engineering), 2024, 48(2): 347-352. (in Chinese)DONG B C, WANG Y X, CHEN S L, et al. Research on mechanical properties of passive earth pressure of treble-row-piles wall retaining and protection structure for deep excavations[J]. Journal of Wuhan University of Technology (Transportation Science & Engineering), 2024, 48(2): 347-352. (in Chinese) [10] 黄伟达. 高边坡三排桩的工作性状及简化算法[J]. 工程勘察, 2017, 45(12): 9-14. (HUANG W D. Performance and simplified calculation of three-row pile of high slope stability retaining structure[J]. Geotechnical Investigation & Surveying, 2017, 45(12): 9-14. (in Chinese)HUANG W D. Performance and simplified calculation of three-row pile of high slope stability retaining structure[J]. Geotechnical Investigation & Surveying, 2017, 45(12): 9-14. (in Chinese) [11] 曹新刚, 丁 飞. 不同工况下三排桩基坑支护特性分析[J]. 安徽建筑, 2020, 27(7): 85-87. (CAO X G, DING F. Analysis of the characteristics of three-row pile foundation pit support under different working conditions[J]. Anhui Architecture, 2020, 27(7): 85-87. (in Chinese)CAO X G, DING F. Analysis of the characteristics of three-row pile foundation pit support under different working conditions[J]. Anhui Architecture, 2020, 27(7): 85-87. (in Chinese) -
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