兰州地铁1号线桥梁桩基托换技术模型试验研究
朱金涌
Model Test Research on Underpinning Technology of Bridge Pile Foundation of Lanzhou Metro Line 1
ZHU Jinyong
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作者信息:兰州铁道设计院有限公司，730000，兰州
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Affiliation:Lanzhou Railway Survey and Design Institute Co., Ltd., 730000, Lanzhou, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2022.01.017
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中图分类号/CLCN:U443.16+3
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栏目/Col:研究报告
摘要:
以兰州地铁1号线穿越鱼儿沟桥工程案例为研究背景，依据桩基托换设计方案填筑室内模型，研究托换前后既有桩和托换桩的桩基竖向位移、桩身轴力和侧摩阻力的变化规律。结果表明：截断3号、4号和5号桩至沉降稳定时，群桩基础的沉降值为0.34 mm，模拟隧道开挖并施作衬砌至沉降稳定时，群桩基础下沉了0.53 mm，表明桩基托换过程中隧道开挖对群桩基础变形的影响大于截桩；截桩后，1号、2号、5号、6号和7号桩的桩顶轴力分别增加了35.88%、54.00%、36.00%、43.67%和26.23%；5号和6号桩的桩身轴力均呈倒梯形分布，且随上部荷载增大桩身轴力和桩侧摩阻力逐渐增大。截桩后，5号和6号桩的上半部分侧摩阻力显著增大，承担上部荷载。上部荷载分别为50 kN和76 kN时，5号和6号桩桩身侧摩阻力急剧减小，桩土界面发生剪切破坏。
Abstracts:
Based on the case study of Lanzhou Metro Line 1 crossing the Yu′ergou Bridge, the indoor model is built according to the pile foundation underpinning design plan, and the variation law of vertical displacement, pile axial force and side friction resistance of piles before and after replacement is studied. The results show that the settlement value of the pile group foundation is 0.34 mm when the No.3, No.4, and No.5 piles are cut until stable settlement. When the tunnel excavation is simulated and the lining is constructed until the settlement is stable, the pile group foundation sinks 0.53 mm, indicating that during underpinning process, the influence of tunnel excavation is greater than pile cutting on pile group foundation deformation; after pile cutting, the pile top axial forces of No.1, No.2, No.5, No.6, and No.7 piles increase by 35.88% and 54.00%, 36.00%, 43.67% and 26.23% respectively; the axial forces of No.5 and No.6 piles are distributed in an inverted trapezoid shape, and the axial force and side friction resistance of the pile gradually increase with the increase of the upper load. After pile cutting, the side friction resistance of upper part of No.5 and No.6 piles increases significantly while bearing the upper load. When the upper load is 50 kN and 76 kN respectively, the side friction resistance of No.5 and No.6 piles decreases drastically, and shear failure occurs at the pile-soil interface.
引文 / Ref:
朱金涌.兰州地铁1号线桥梁桩基托换技术模型试验研究[J].城市轨道交通研究，2022，25（1）：86.
ZHU Jinyong.Model Test Research on Underpinning Technology of Bridge Pile Foundation of Lanzhou Metro Line 1[J].Urban mass transit，2022，25（1）：86
ZHU Jinyong.Model Test Research on Underpinning Technology of Bridge Pile Foundation of Lanzhou Metro Line 1[J].Urban mass transit，2022，25（1）：86
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