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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Influence of the penetration of adjacent X-section cast-in-place concrete (XCC) pile on the existing XCC pile in sand

Abstract: A series of small-scale 1g X-section cast-in-place concrete (XCC) pile-penetration model tests were conducted to study the effects of soil density and pile geometry on the lateral responses of an existing pile and the variations in surrounding soil stress. The results showed that the bending patterns of existing XCC piles varied with penetration depth. The lateral response of the existing pile was sensitive to the change in relative density and pile geometry. For example, the bending moment of the existing pile increased along with these parameters. The development of the radial stress σ'r/σ'v0 of the soil around an existing pile showed different trends at various depths during the penetration of the adjacent pile. Moreover, the change in radial stress during the penetration of the XCC pile did not exhibit the “h/R effect” that was observed in the free-field soil, due to the shielding effect of the existing piles. The peak value of radial stress σ'r_max/σ'v0 decreased exponentially as the radial distance r/R increased. The attenuation of σ'r_max/σ'v0 with r/R in the loose sand was faster than in the medium-dense or dense sands. The σ'r_max/σ'v0 at the same soil location increased with the cross-section geometry parameter.

Key words: X-section cast-in-place concrete (XCC) pile; Test; Penetration; Sand; Lateral response; Radial stress

Chinese Summary  <12> 砂土中相邻现浇X形混凝土(XCC)桩贯入对既有XCC桩的影响研究

作者:周鹏1,2,3,徐建辉1,徐长节1,曹光伟4,崔杰2,丁选明3
机构:1华东交通大学,土木建筑学院,轨道交通基础设施性能监测与保障国家重点实验室,中国南昌,330013;2广州大学,工程抗震研究中心,广东省地震工程与应用技术重点实验室,中国广州,510006;3重庆大学,土木工程学院,中国重庆,400045;4福州大学,紫金地质与矿业学院,中国福州,350116
目的:在实际工程施工过程中,由于XCC桩属于挤土桩,其安装或沉桩过程将使桩周土体产生变形,而这种挤土荷载(尤其是侧向挤土位移)会对既有桩施加附加的桩身响应,从而导致桩基破坏。本文旨在探讨砂土中相邻XCC桩贯入对既有XCC桩的影响,研究贯入过程中不同土体相对密实度和既有桩截面几何形状的情形下既有桩侧向响应及桩周土体应力的发展规律。
创新点:1.探讨了相对密实度和截面几何形状对既有桩侧向响应的影响;2.揭示了贯入过程中既有桩桩周土体应力变化规律。
方法:1.基于沉桩加载模型试验系统,开展一系列砂土中相邻XCC桩贯入对既有XCC桩影响的1g模型试验;2.考虑土体相对密实度和既有桩截面几何效应的影响,获得砂土中相邻XCC桩贯入过程中既有XCC桩的侧向响应以及桩周土体应力变化的趋势。
结论:1.既有XCC桩侧向响应对相对密实度和截面几何效应的变化很敏感,主要表现为既有XCC桩的弯矩随着它们的增加而增大;2.既有XCC桩周围不同深度的土体径向应力随贯入深度的变化呈现出不同的发展趋势,而且由于既有桩的遮挡效应,土体的径向应力的变化不再表现出"h/R效应";3.径向应力峰值σ’r_max/σ’v0随着径向距离r/R的增加而以指数函数的形式减小,松砂中σ’r_max/σ’v0r/R的衰减指数要大于中密砂和密砂中的衰减指数。

关键词组:XCC桩;贯入;模型试验;侧向响应;径向应力


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DOI:

10.1631/jzus.A2300384

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On-line Access:

2024-08-27

Received:

2023-10-17

Revision Accepted:

2024-05-08

Crosschecked:

2024-07-24

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