| 盾构切削桩引起的桩基承载特性变化及可行性研究* |
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| 引用本文： | 李景茂,王旭,王博林,牛亚强.盾构切削桩引起的桩基承载特性变化及可行性研究*[J].中国安全生产科学技术,2021,17(5):26-32. |
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| 作者姓名： | 李景茂 王旭 王博林 牛亚强 |
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| 作者单位： | （1.兰州交通大学 土木工程学院，甘肃 兰州 730070；2.兰州交通大学 道桥工程灾害防治技术国家地方联合工程实验室，甘肃 兰州 730070） |
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| 基金项目： | * 基金项目: 国家自然科学基金项目（41662017） |
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| 摘 要： | 为分析兰州地铁盾构隧道穿越既有桥梁工程方案的可行性，采用有限元数值模拟，研究盾构施工切削桩引起的桩基承载特性变化，分析盾构切削桩基前后桩体轴力、侧摩阻力和弯矩变化，探讨地表及桩基的位移变化。结果表明:直接切削桩将导致桩顶荷载重分布，隧道两侧1，4号桩桩顶荷载增大且增大19.3%~26.7%，而切断桩荷载减小且减小25.5%~29.2%；桩土相对位移随着盾构掘进而增大，促使基桩侧摩阻力的发挥整体呈增强趋势；各基桩弯矩均增大，致使桩基在桩顶以下4 m及隧道中心平面附近存在2个不利截面，各基桩最大弯矩增大2.0~5.2倍；直接切削桩将导致地表、基桩沉降激增，从而导致水平位移增大，致使承台由初始受力状态时的整体沉降变为挠曲变形为主，最大相对沉降达到5.01 mm，超过控制限值。可见，直接切削桩对既有桥梁桩基的承载特性影响显著，此方案不可行，应在盾构施工前采取加固措施。该研究结果可为类似工程提供参考。
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| 关 键 词： | 地铁 承载特性 数值计算 桩基础 可行性 |
Research on change of pile foundation bearing characteristics caused by shield cutting piles and its feasibility |
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| LI Jingmao,WANG Xu,WANG Bolin,NIU Yaqiang.Research on change of pile foundation bearing characteristics caused by shield cutting piles and its feasibility[J].Journal of Safety Science and Technology,2021,17(5):26-32. |
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| Authors: | LI Jingmao WANG Xu WANG Bolin NIU Yaqiang |
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| Affiliation: | (1.School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou Gansu 730070,China;2.National and Provincial Joint Engineering Laboratory of Road & Bridge Disaster Prevention and Control,Lanzhou Jiaotong University,Lanzhou Gansu 730070,China) |
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| Abstract: | In order to analyze the feasibility of engineering scheme for the shield tunnel crossing the existing bridge in Lanzhou subway,the finite element numerical simulation was used to study the bearing characteristics variation of pile foundation caused by cutting piles in shield construction.The change of axial force,side friction resistance and bending moment of the pile body before and after the shield cutting pile foundation were analyzed,and the displacement change of the ground surface and the pile foundation were discussed.The results showed that the direct cutting piles would lead to the load redistribution on the pile top.The load at pile top of the pile No.1 and pile No.4 on both sides of the tunnel increased by 19.3%~26.7%,while the load of cut-off pile decreased by 25.5%~29.2%.The relative displacement of pile and soil increased due to the shield excavation,which made the lateral friction resistance of foundation pile increase as a whole.The bending moment of each pile increased,resulting in two unfavorable sections of pile foundation at 4 m below the pile top and near the central plane of the tunnel,and the maximum bending moment of each foundation pile increased by 2.0~5.2 times.The direct cutting piles would lead to the sharp increase in the settlement of ground surface and foundation pile,thus cause the increase of horizontal displacement,resulting in the change from the overall settlement of the pile cap in the initial stress state to the dominated flexural deformation,and the maximum relative settlement reached 5.01 mm,exceeding the control limit.It could be seen that the direct cutting piles had significant influence on the bearing characteristics of the existing bridge pile foundation,so this scheme was not feasible,and the reinforcement measures should be taken before the shield construction.The research results can provide reference for similar projects. |
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| Keywords: | subway bearing characteristic numerical calculation pile foundation feasibility |
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