复合地基与临近基坑支护结构之间距离影响规律

doi:10.6040/j.issn.1672-3961.0.2018.345

摘要/Abstract

摘要：

基于复合地基与支护结构紧邻情况的离心试验,使用PLAXIS软件,建立复合地基与支护结构之间有一定距离的基坑工程数值模型,研究土条宽度对复合地基与支护结构内力位移的影响规律。结果表明:距离规律可分三个区间:当土条宽度从0增加至6 m, CFG桩轴力与桩土应力比增大,遮拦效应明显,宜建立考虑侧向刚度和遮拦效应的侧压力计算方法主动控制位移;当土条宽度从6 m增加至至18 m, CFG桩轴力、桩土应力比稳定减少,可沿用现有设计算法;土条宽度增加至18 m及以上,新建基坑对既有复合地基不再产生影响。研究结果明确了不同土条宽度下基坑设计方向,以及同类基坑工程中安全防护重点,为进一步建立此类基坑的设计理论奠定了基础。

关键词: 复合地基, 支护结构, 间距

Abstract:

Based on the centrifugal test of the close relationship between the composite foundation and the supporting structure, the PLAXIS software was used to establish a numerical model of the foundation pit with a certain distance between the composite foundation and the supporting structure. This model was used to study the influence of the width of the strip on internal force and displacement of the composite foundation and retaining structure. The results showed that the distance law could be divided into three sections: when the width of the soil strip increased from 0 to 6 m, the axial force of the CFG pile and the pile-soil stress ratio increased, and the obstruction effect was obvious. It was advisable to establish a lateral pressure calculation method that considered the lateral stiffness and the obstruction effect to actively control the displacement. When the width of the soil strip was 6 m to 18 m, the axial force of the CFG pile and the pile-soil stress ratio were steadily reduced. When the width of the soil strip was increased to 18 m or more, there was no longer any influence between the new foundation pit and the existing composite foundation. The research results clarified the design direction of foundation pits under different widths of soil and the safety protection focus of similar foundation pit engineering, which laid a foundation for further establishing the design theory of such foundation pits.

Key words: composite foundation, support structure, strip width

中图分类号:

TU43

李连祥, 白璐, 陈天宇, 季相凯. 复合地基与临近基坑支护结构之间距离影响规律[J]. 山东大学学报 (工学版), 2019, 49(3): 63-72.

Lianxiang LI, Lu BAI, Tianyu CHEN, Xiangkai JI. Influence rule of foundation pit supporting structure and its adjacent composite foundation distance[J]. Journal of Shandong University(Engineering Science), 2019, 49(3): 63-72.

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桩参数	置换率	尺寸/mm×mm(×mm)	桩间距/mm
模型	0.031 3	20×0.5×350	100
原型	0.031 3	400×14 000	2 000
数值模型	0.031 3	800×14 000	3 200

项目	D_r	干密度γ_d (/kN·m^-3)	粘聚力 c/kPa	平均粒径 d₅₀/mm	项目	天然孔隙比e	e_min	e_max	内摩擦角 φ/°
福建砂	85%	15.9	0	0.17	取值	0.663	0.6 117	0.957	33

部件	密度/(kg·m^-3)	弹性模量/MPa	泊松比
支护板	2.7	68.9×10³	0.33
CFG桩	2.7	68.9×10³	0.33
褥垫层	2.5	45	0.33

编号	组别	土条宽度/m	上覆荷载/kPa	CFG桩
1	有桩有载	0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24	180	有
2	无桩有载	0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24	180	无
3	无桩无载			无

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