Research purposes: To study the prestress loss of the anchor cables for super deep foundation pits in soft rock formations and propose corresponding tensioning plans, based on the deep foundation pit project of Huanghua Airport underground station on the Changsha-Ganzhou high-speed railway, comparative experimental research on traditional monitoring of anchor cable axial force and distributed grating fiber optic monitoring was carried out, a numerical model was established for the entire process of anchor cable tensioning in deep foundation pits in soft rock formations, and the prestress loss during the tensioning process of each anchor cable and the deformations of the side wall of the foundation pit were analyzed.
Research conclusions: (1) The prestress losses of the anchor cables in deep foundation pits in soft rock formations are relatively serious, and the prestress losses of some anchor cables can reach over 30%. (2) The prestress losses in the anchor cable are mainly due to anchoring which mainly occurs within 120 minutes after anchoring, and the greater the initial tensioning force of the anchor cable, the more prestress losses after anchoring. (3) For the prestressed anchor cables of the super deep foundation pits in soft rock formations, a step-by-step over tensioning scheme can more effectively decrease the prestress losses caused by the anchoring and tensioning process of the anchor cables, reduce the side wall deformations of the foundation pit, reduce the impact of excavation on the surrounding environment, and then guide the construction of prestressed anchor cables effectively.
Key words
super deep foundation pit /
grating fiber /
tensioning scheme /
numerical simulation /
prestressed anchor cables /
prestress loss /
cast-in-place piles
{{custom_keyword}} /
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] 张广超,侯强松,吉兆腾,等.咬合桩-旋喷锚索基坑支护体系分析[J].铁道工程学报,2022(5):14-19.
Zhang Guangchao,Hou Qiangsong,Ji Zhaoteng,etc. Analysis of Retaining System of Secant Pile-rotary Anchor Cable for Foundation Pit Excavation[J].Journal of Railway Engineering Society,2022(5):14-19.
[2] 成潇博,姚华彦,汪明武,等.树根桩与预应力桩联合加固边坡稳定性与敏感性分析[J].水利水运工程学报, 2024(1): 129-137.
Cheng Xiaobo,Yao Huayan,Wang Mingwu,etc. Analysis of the Stability and Sensitivity of Slope Reinforcement Using Combined Root Piles and Prestressed Piles[J].Hydro-Science and Engineering, 2024(1): 129-137.
[3] 余瑜,刘新荣,刘永权.基坑锚索预应力损失规律现场试验研究[J].岩土力学,2019(5):1932-1939.
Yu Yu, Liu Xinrong, Liu Yongquan.Field Experimental Investigation on Prestress Loss Law of Anchor Cable in Foundation Pits[J].Rock and Soil Mechanics, 2019(5): 1932-1939.
[4] Yang Zhongping, Li Shiqi, Yu Yu,etc. Study on the Variation Characteristics of the Anchor Cable Prestress Based on Field Monitoring in a Foundation Pit[J].Arabian Journal of Geosciences, 2020(13):1-10.
[5] 刘新荣,刘永权,康景文,等.基坑锚索预应力损失规律及分步张拉控制措施研究[J].岩土工程学报,2015(10):1794-1801.
Liu Xinrong,Liu Yongquan,Kang Jingwen,etc.Prestress Loss Laws of Anchor Cables in Foundation Pits and Control Measures of Tension by Steps[J].Chinese Journal of Geotechnical Engineering,2015(10):1794-1801.
[6] 毛佳艳,高晓辉.地铁基坑锚索支护应力损失原因及应对措施探讨[J].国防交通工程与技术,2017(4):52-55.
Mao Jiayan,Gao Xiaohui.An Exploration into the Causes for the Loss of the Supporting Stress of the Anchoring Cables for the Foundation Pit of the Subway and the Countermeasures[J].Traffic Engineering and Technology for National Defence,2017(4):52-55.
[7] 任志亮. 复杂环境下地铁车站超深基坑锚索应力损失控制研究[J].铁道科学与工程学报,2020(12):3157-3165.
Ren Zhiliang.Study on Stress Loss Control of Anchor Cable in Super Deep Foundation Pit of Metro Station in Complex Environment[J].Journal of Railway Science and Engineering,2020(12):3157-3165.
[8] 刘学,郭廷科,沈龙,等.土岩复合地层不同锚固长度预应力锚索锚固机制及现场测试[J].隧道建设(中英文),2023(S1):154-162.
Liu Xue,Guo Tingke,Shen Long,etc.Anchorage Mechanism and Field Tests of Prestressed Anchor Cables with Different Anchorage Lengths in Soil-rock Composite Strata[J].Tunnel Construction,2023(S1):154-162.
{{custom_fnGroup.title_en}}
Footnotes
{{custom_fn.content}}
PDF(1085 KB)
