（1 东南大学土木工程学院， 南京 210096； 2中交公路规划设计院有限公司， 北京 100088）

［摘要］为了研究刚性桩复合地基垫层土拱效应的作用机理，通过可视化模型箱对不同桩间距及垫层厚度的刚性桩复合地基进行了室内模型试验，利用数字图像无标点量测技术研究土体颗粒的变形场，对桩顶垫层土体形成土拱的变化过程进行全面观测与分析，研究复合地基垫层土拱效应。利用离散元颗粒流方法，研究了复合地基桩间距、桩径、垫层土体厚度、土体内摩擦角和密实度等宏细观因素对土拱效应的影响规律。对离散元颗粒流模拟结果与室内模型试验结果进行对比分析，结果表明：垫层厚度越大、桩间距越小，垫层形成的土拱效应就越明显；土体摩擦系数、孔隙率对土拱效应影响较大，而桩径对土拱效应影响较小。刚性桩复合地基垫层土拱效应机理的研究对于提高垫层设计水平具有重要的参考价值。

［关键词］复合地基; 垫层; 土拱效应; 颗粒流

中图分类号：TU473      文献标识码：A      文章编号：1002-848X(2014)01-0082-06

Macro and micro-mechanism analysis of soil arching effect in the cushion of rigid pile composite foundation

Zhu Xiaojun1, Zhao Xueliang1, Gong Weiming1, Xu Guoping2

(1 School of Civil Engineering, Southeast University, Nanjing 210096, China; 2 CCCC Highway Consultants Co., Ltd., Beijing 100088, China)

Abstract: In order to investigate the mechanism of the soil arching effect in the cushion of the rigid pile composite foundation, laboratory experiments of rigid pile composite foundation with different pile spacing and cushion thickness were carried out in a tempered glass box. Particle image velocimetry (PIV) and digital speckle correlation technique were used to investigate the deformation fields of soil in the cushion of composite foundation. The development of soil arching in the cushion was observed and analyzed globally to study the soil arching effect in the cushion of composite foundation. Particle flow code (PFC) of discrete element method was used to study the effects of factors including the pile spacing, pile diameter, cushion thickness, internal friction angle and compactness of soil on the soil arching effect. The results of particle flow code numerical simulation and model tests were compared. The results show that the soil arching is easier to form with smaller pile spacing, thicker cushion. Influence of friction coefficient and porosity of soil particles on the soil arching effect is great, but influence of pile diameter on it is small. The study on mechanism of the soil arching effect in the cushion of rigid pile composite foundation can raise the cushion design level.

Keywords: composite foundation; cushion; soil arching effect; particle flow code

*“十二五”国家支撑计划资助项目（2011BAG07B01），国家重点研究基础发展计划（973计划）资助项目（2013CB036304），国家自然科学基金资助项目（51079030）。

作者简介：朱小军, 博士研究生，Email：crazygray@163.com。

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