- 摘 要
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（1 東南大學土木工程學院， 南京 210096； 2中交公路規(guī)劃設計院有限公司， 北京 100088）
［摘要］為了研究剛性樁復合地基墊層土拱效應的作用機理，通過可視化模型箱對不同樁間距及墊層厚度的剛性樁復合地基進行了室內模型試驗，利用數字圖像無標點量測技術研究土體顆粒的變形場，對樁頂墊層土體形成土拱的變化過程進行全面觀測與分析，研究復合地基墊層土拱效應。利用離散元顆粒流方法，研究了復合地基樁間距、樁徑、墊層土體厚度、土體內摩擦角和密實度等宏細觀因素對土拱效應的影響規(guī)律。對離散元顆粒流模擬結果與室內模型試驗結果進行對比分析，結果表明：墊層厚度越大、樁間距越小，墊層形成的土拱效應就越明顯；土體摩擦系數、孔隙率對土拱效應影響較大，而樁徑對土拱效應影響較小。剛性樁復合地基墊層土拱效應機理的研究對于提高墊層設計水平具有重要的參考價值。
［關鍵詞］復合地基; 墊層; 土拱效應; 顆粒流
中圖分類號：TU473 文獻標識碼：A 文章編號：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”國家支撐計劃資助項目（2011BAG07B01），國家重點研究基礎發(fā)展計劃（973計劃）資助項目（2013CB036304），國家自然科學基金資助項目（51079030）。
作者簡介：朱小軍, 博士研究生，Email：crazygray@163.com。
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