刚性桩复合地基与临近基坑支护结构相互影响的离心模型试验

doi:10.13722/j.cnki.jrme.2017.0157

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摘要

目前缺乏复合地基与临近基坑支护结构相互影响的相关研究。为了研究复合地基及其支护结构受侧向开挖的影响，通过两组相同荷载相同支护结构、不同置换率的复合地基侧向开挖离心模型试验，分析了桩轴力及侧摩阻力、桩土应力比、桩间土竖向应力、桩弯矩和支护结构弯矩随开挖的变化规律，及其受置换率变化的影响。结果表明：桩轴力、桩土应力比、桩弯矩及支护结构弯矩随开挖递增，桩侧摩阻力及桩间土竖向应力受开挖影响较小，桩身上部摩阻力方向向下，桩身下部向上，支护结构弯矩最大值位置随开挖逐级下移；距基坑的距离决定桩弯矩的大小和变化形式，在距基坑较近处因桩土不均匀沉降明显，桩顶上刺入褥垫层，褥垫层对桩顶有水平约束，引起桩上部负弯矩；除置换率对桩间土竖向应力影响较小外，上述各项力学性状均因置换率的增大而减小，其中支护结构弯矩减小程度最大，表明复合地基置换率增大能够有效改善复合地基和支护结构受力性状，增强其侧向基坑开挖安全性。

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	李连祥1
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	黄佳佳1
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	成晓阳1
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	胡峰1
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	符庆宏1
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关键词 ：桩基工程, 置换率, 开挖内力, 离心模型试验, 复合地基, 支护结构

Abstract：

There is a lack of research on the interaction between composite foundation and its retaining structure at present. To study the interaction between rigid-pile composite foundation in the vicinity of a deep excavation and its retaining structure affected by lateral excavation，two centrifuge model tests of composite foundation with lateral excavation which had the same load，same supporting structure and different replacement rates were carried out. It is analysis to the change laws with excavation of the pile axial force，the lateral frictional resistance，the pile-soil stress ratio，the vertical stress of the soil between piles，the moments of piles and the retaining structure，and their response to changes in replacement rate. The result shows that the pile axial force，pile-soil stress ratio，moments of piles and retaining structure increase with excavation，while the lateral frictional resistance and the vertical stress are less affected by excavation. The frictional resistance direction in the upper part of pile body is downward，and upward in the lower part. The position with the maximum value of retaining structure moment moves down step by step with excavation. The distance from the foundation pit determines the magnitude and the change form of pile bending moment. The pile top near foundation pit embeds cushion due to uneven settlement of piles and soil，and is constrained horizontally by cushion，which causes the negative moment in the upper part of the pile. Except that the replacement rate has little influence on the vertical stress of the soil between piles，all the above mechanical properties are decreased as the result of the increase of replacement rate，especially for the retaining structure moment，which indicates that the replacement rate of composite foundation can be increased to improve the mechanical properties of composite foundation and its support structure，and enhance the safety of lateral excavation.

Key words： pile foundations replacement rate internal force of excavation centrifugal model test composite foundation retaining structure

引用本文:

李连祥1，2，黄佳佳1，2，成晓阳1，2，胡峰1，2，符庆宏1，2. 刚性桩复合地基与临近基坑支护结构相互影响的离心模型试验[J]. 岩石力学与工程学报, 2017, 36(S2): 4142-4150.
LI Lianxiang1，2，HUANG Jiajia1，2，CHENG Xiaoyang1，2，HU Feng1，2，FU Qinghong1，2. Centrifuge model tests on the interaction between rigid-pile composite foundation in the vicinity of a deep excavation and its retaining structure. , 2017, 36(S2): 4142-4150.

链接本文:

https://rockmech.whrsm.ac.cn/CN/10.13722/j.cnki.jrme.2017.0157 或 https://rockmech.whrsm.ac.cn/CN/Y2017/V36/IS2/4142

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