不同路堤高度下X形桩-筏复合地基动力响应模型试验

孙广超; 孔纲强; 李建林; 罗雅

doi:10.11779/CJGE2021S2011

不同路堤高度下X形桩-筏复合地基动力响应模型试验 English Version

孙广超^{1, 2, 3,},
孔纲强^{1, 2, ,},
李建林¹,
罗雅³

1.
三峡大学三峡库区地质灾害教育部重点实验室,湖北　宜昌　443002
2.
河海大学岩土力学与堤坝工程教育部重点实验室,江苏　南京　210098
3.
深圳市龙岗区建筑工务署,广东　深圳　518100

基金项目:

国家自然科学基金重点国际（地区）合作研究项目 51420105013

高速铁路基础研究联合基金项目 U2034203

国家自然科学基金青年基金项目 51809151

详细信息

作者简介:
孙广超(1986— ),男,河南开封人,博士,主要从事桩-土相互作用方面的研究。E-mail: sgcgeo@163.com

通讯作者:
孔纲强, E-mail: gqkong1@163.com

中图分类号: U416.1;TU473
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- 文章访问数: 187
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- PDF下载量: 84
出版历程
- 收稿日期: 2021-08-15
- 网络出版日期: 2022-12-05
- 刊出日期: 2021-10-31

Model tests on dynamic response of XCC pile-raft composite foundation under different embankment heights

SUN Guang-chao^{1, 2, 3,},
KONG Gang-qiang^{1, 2, ,},
LI Jian-lin¹,
LUO Ya³

1.
Key Laboratory of Geological Hazards on Three Gorges Reservoir Area, China Three Gorges University, Yichang 443002, China
2.
Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University, Nanjing 210098, China
3.
Bureau Public Works of Longgang District, Shenzhen 518100, China

摘要

摘要: 为了明确路堤高度对桩-筏复合地基动力响应的影响,在砂土中展开了X形桩筏复合地基大比尺模型试验。在尺寸为5 m ×4 m×7 m的模型槽里,通过将4种不同的路堤高度换算成对应的恒载然后预先施加于筏板上,再在筏板上施加循环的轮轴荷载,从而得出动力响应随恒载（即路堤高度）的变化规律。试验结果表明：由于碎石垫层的存在,速度响应从筏板顶部到地基深度0 m的0.36 m范围内速度响应锐减了34%～40%。随着恒载的增加,轮轴荷载引起的筏板振动情况逐渐减弱,筏板的速度响应v'与恒载x之间的关系曲线为v'=12.648-0.519x+0.007x²；地基表层动土压力与桩顶动应力随恒载的增加均呈线性减小,其中地基表层的动土压力σ_sd与恒载x之间的关系曲线为σ_sd=7.629-0.085x,桩顶动应力σ_pd与恒载x之间的关系曲线为σ_pd=284.978-3.660x。
- 桩-筏复合地基 /
- 模型试验 /
- X形桩 /
- 路堤高度 /
- 动力响应
Abstract: In order to investigate the influences of embankment height on the dynamic response of pile-raft composite foundation, a large-scale model test on the cast-in-situ X-shaped concrete (referred to as XCC) pile-raft composite foundation is carried out in a model box of 5 m× 4 m×7 m. Four different embankment heights are modeled as the dead loads, and the cyclic wheel axle load is applied to the raft so as to obtain the dynamic response with the dead loads (i.e., embankment height). The results show that the velocity response decreases by 34% ~ 40% from the top of the raft to 0.36 m depth of foundation due to the existence of a gravel cushion. The vibration of the raft caused by the axle load decreases gradually with the increasing dead loads. The relationship between the velocity response of the raft v' and the dead load x is defined by the equation, v' = 12.648-0.519x+0.007x². Both the dynamic soil stress on the surface of the foundation σ_sd and the dynamic stress at the top of the pile σ_pd decrease linearly with the increasing dead loads x. The former is defined by the equation σ_sd= 7.629-0.085x, whereas the latter is defined by σ_pd= 284.978-3.660x.
- pile-raft foundation /
- model test /
- XCC pile /
- embankment height /
- dynamic response

HTML全文

图 1 不同路堤高度下X形桩-筏复合地基

Figure 1. XCC pile−raft composite foundation under different embankment heights

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图 2 试验加载示意图

Figure 2. Schematic diagram of test loading

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图 3 X形桩及布置示意图

Figure 3. Arrangement of XCC piles

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图 4 试验仪器布置示意图

Figure 4. Layout of instruments for model tests

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图 5 施加的正弦波荷载

Figure 5. Dine wave loads

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图 6 速度响应时程曲线

Figure 6. Time-history curves of velocity response

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图 7 速度响应与深度的关系

Figure 7. Vibration velocities recorded at different layers

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图 8 筏板速度响应与恒载的关系曲线

Figure 8. Relationship between velocity response of raft and dead load

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图 9 动土压力时程曲线

Figure 9. Time-history curves of dynamic soil pressure

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图 10 地基表层动土压力与恒载的关系曲线

Figure 10. Relationship between dynamic soil pressure of foundation surface and dead load

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图 11 桩顶动应力与恒载关系曲线

Figure 11. Dynamic stress of pile top versus dead load

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表 1 模型相似比

Table 1 Similarity ratios for model

参数	相似比	参数	相似比
长度/m	1/5	体积/m³	1/125
密度/(kg·m^-3)	1	弹性模量/MPa	1
加速度/(m·s^-2)	1	力/kN	1/5
应力/kPa	5	速度/(m·s^-1)	$1 / \sqrt{5}$ $1 / \sqrt{5}$
时间/s	$1 / \sqrt{5}$ $1 / \sqrt{5}$	频率/kPa	$\sqrt{5}$ $\sqrt{5}$

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表 2 砂土基本物理指标

Table 2 Physical indices of sand

天然密度/(g·cm^-3)	天然含水率/%	G_s	不均匀系数C_u	曲率系数C_c
1.478	4.08	2.67	2.42	0.93

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表 3 试验加载工况

Table 3 Load cases of tests

荷载Q(t)/kN	恒载x/kN	振幅A/kN	频率f/Hz	循环次数/次
Q(t)	20	5	10	25000
Q(t)	25	5	10	25000
Q(t)	30	5	10	25000
Q(t)	35	5	10	25000

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不同路堤高度下X形桩-筏复合地基动力响应模型试验 English Version

作者简介: 孙广超(1986— ),男,河南开封人,博士,主要从事桩-土相互作用方面的研究。E-mail: sgcgeo@163.com

通讯作者: 孔纲强, E-mail: gqkong1@163.com

计量

出版历程

Model tests on dynamic response of XCC pile-raft composite foundation under different embankment heights

计量

出版历程

目录

作者简介:
孙广超(1986— ),男,河南开封人,博士,主要从事桩-土相互作用方面的研究。E-mail: sgcgeo@163.com

通讯作者:
孔纲强, E-mail: gqkong1@163.com