剪力键支护体系的构想及模型试验研究
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摘要
针对深大基坑支护工程中存在的问题提出了一种新型的支护形式-剪力键支护体系,由竖直桩和斜向支撑的剪力键构成。通过模型试验,对剪力键组和单排悬臂桩组分别量测了不同开挖深度时的桩顶水平位移及桩身内力,同时进行了有限元的数值模拟。结果表明剪力键组的桩顶最大水平位移约为悬臂组的1/10,桩身最大弯矩值约为悬臂组的一半左右。剪力键支护体系具有更大的刚度,能够有效减小桩顶位移及桩身最大弯矩,且耗材相对较少,支护深度较大,占据空间较少,不影响主体地下室施工,可节约工期和成本,为深大基坑的支护提供了新的型式。
In this paper, a new type of support form-shear bond supporting system, which is composed of vertical and oblique piles, is put forward for deep and large foundation pit construction. Through model test, the horizontal displacement of pile top and internal force of pile body are measured at different excavation depths for shear bond group and single row cantilever pile group, respectively. Finite element numerical simulation is carried out at the same time. The results show that the maximum horizontal displacement of the pile top in shear bond group is about 1/10 of that in cantilever group, and the maximum bending moment of the pile in shear bond group is about half of that in cantilever group. Shear bond supporting system has greater stiffness, and it can effectively reduce the displacement of pile top and the maximum bending moment of pile body. It consumes less material, is able to support deeper excavation, and occupies less space, which will not hinder the construction of the main basement. Therefore, it can save time and cost, and provide a new idea for deep foundation pit supporting.
In this paper, a new type of support form-shear bond supporting system, which is composed of vertical and oblique piles, is put forward for deep and large foundation pit construction. Through model test, the horizontal displacement of pile top and internal force of pile body are measured at different excavation depths for shear bond group and single row cantilever pile group, respectively. Finite element numerical simulation is carried out at the same time. The results show that the maximum horizontal displacement of the pile top in shear bond group is about 1/10 of that in cantilever group, and the maximum bending moment of the pile in shear bond group is about half of that in cantilever group. Shear bond supporting system has greater stiffness, and it can effectively reduce the displacement of pile top and the maximum bending moment of pile body. It consumes less material, is able to support deeper excavation, and occupies less space, which will not hinder the construction of the main basement. Therefore, it can save time and cost, and provide a new idea for deep foundation pit supporting.
引文
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[2]丁杰明,巢丝,吴宏磊,等.上海中心大厦绿色结构设计关键技术[J].建筑结构学报,2017,38(3):134-40.DING Jie-min,CHAO Si,WU Hong-lei,et al.Key technology of green building in the Shanghai Tower structural design[J].Journal of Building Structures,2017,38(3):134-140.
[3]夏彪.h型双排桩在基坑工程中的变形特性研究[D].衡阳:南华大学,2016.XIA Biao.The deformation characteristics research of h-type double-row piles in foundation engineering[D].Hengyang:University of South China,2016.
[4]李启明,何满潮,唐业清.挤扩支盘支护桩试验研究[J].岩土力学,2005,26(10):1667-1670.LI Qi-ming,HE Man-chao,TANG Ye-qing.Experimental study on squeezed branch piles as retaining and protecting of foundation excavation[J].Rock and Soil Mechanics,2005,26(10):1667-1670.
[5]徐源,郑刚,路平.前排桩倾斜的双排桩在水平荷载下的性状研究[J].岩土工程学报,2010,32(增刊1):93-98.XU Yuan,ZHENG Gang,LU Ping.Behaviors of double-row contiguous retaining piles with raking front-row piles under horizontal loads[J].Chinese Journal of Geotechnical Engineering,2010,32(Suppl.1):93-98.
[6]郑刚,聂东清,程雪松,等.基坑分级支护的模型试验研究[J].岩土工程学报,2017,39(5):784-794.ZHENG Gang,NIE Dong-qing,CHENG Xue-song,et al.Experimental study on multi-bench retaining foundation pits[J].Chinese Journal of Geotechnical Engineering,2017,39(5):784-794.
[7]郑刚,聂东清,刁钰,等.基坑多级支护破坏模式研究[J].岩土力学,2017,38(增刊1):313-322.ZHENG Gang,NIE Dong-qing,DIAO Yu,et al.Failure mechanism of multi-bench retained foundation pit[J].Rock and Soil Mechanics,2017,38(Suppl.1):313-322.
[8]马郧.武汉长江I级阶地超深基坑支护结构设计参数选取与变形关系研究-以中海国际大厦超深基坑工程为例[D].武汉:中国地质大学,2014.MA Yun.Research on the relationship between deformation and design parameters for ultra deep foundation pit retaining structure in Wuhan Yangtze River I terrace-take ultra deep foundation pit of Zhonghai International Building as example[D].Wuhan:China University of Geosciences,2014.
[9]马郧,魏志云,徐光黎,等.基坑双排桩支护结构设计计算软件开发及应用[J].岩土力学,2014,35(3):862-870.MA Yun,WEI Zhi-yun,XU Guang-li,et al.Development of design software of double-row piles for foundation pits and its application[J].Rock and Soil Mechanics,2014,35(3):862-870.
[10]俞晓.深基坑开挖与支护的模型试验与ANSYS分析研究[D].武汉:武汉理工大学,2005.YU Xiao.Research on model test of deep excavation bracing and numerical simulation with ANSYS[D].Wuhan:Wuhan University of Technology,2005.
[11]中华人民共和国住房和城乡建设部.JGJ 120-2012建筑基坑支护技术规程[S].北京:中国建筑工业出版社,2012.Ministry of Housing and Urban-Rural Construction of the People’s Republic of China.JGJ 120-2012 Technical specification for retaining and protection of building foundation excavations[S].Beijing:China Architecture and Building Press,2012.