长群桩基础沉降性状的大比例尺模型试验研究  

Large scale model tests on settlement characteristics of long pile group foundation

作　　者：秋仁东[1] 刘金砺[1] 高文生[1] 邱明兵[1] 

机构地区：[1]中国建筑科学研究院,北京100013

出　　处：《土木工程学报》2015年第3期85-95,共11页China Civil Engineering Journal

基　　金："十二五"国家科技支撑计划(2012BAJ07B01)

摘　　要：随着高层超高层建筑的兴建和快速发展,长桩超长桩的使用随之增多,设计中长桩、超长桩桩基的沉降计算成为一个新的关注焦点。工程单桩静力试桩结果表明,桩身压缩占桩基沉降的比率较大。目前有关长桩基础沉降机理的分析大都基于工程试验的单桩获得,有关长群桩基础的沉降变形性状的机理研究较少,亟需深入研究。为此,以长群桩基础为对象,对其沉降性状进行较为系统的研究。研究表明:1单桩基础在小荷载水平下,桩顶的沉降大都由桩身压缩量所引起;2工作荷载条件下,群桩基础中基桩的桩身压缩比例要小于单桩基础的试验结果,这是由群桩效应导致桩端下土体压缩量比例较大引起;3桩距小、桩数多,土的压缩层厚度大,压缩变形量大,但桩间土的压缩量相对较小;4桩距大、桩数相同情况下,桩端以下的压缩层深度和压缩量将相应减小。研究的相关结果对今后长桩的理论研究和工程设计应用具有一定的借鉴价值。The high-rise and super high-rise buildings have been constructed rapidly with the development of economy and society in China. As the applications of pile-group foundation with long and super-long piles in the buildings are becoming popular,attention has been focused on the calculation of the settlement of such types of pile-group foundations during design. The results of single pile static loading test show that,the compression of pile shaft constitutes a large proportion of pile-group foundation settlement. At present,most research achievements on settlement characteristics of long pile-group foundation were attained based on the single pile static loading test,and there have been few studies carried out on the mechanism of settlement deformation of long pile-group foundation,thus posing the necessity of intensive study. In this work,a brief summary of the large scale model tests is provided,and the main conclusions are summarized as follows: First,for a single pile foundation under a small load level,the settlement of pile top is almost attributed to the compression of pile shaft. Second,under the working load conditions,the compression ratio of pile shaft in the pile-group foundation is less than that of a single pile. Third,when the spacing of piles is small,the number of piles is large and the thickness of soil compression layer is large,the compression deformation of the pile-group foundation shall be large,but the compression of inter-pile soil is relatively small. Fourth,for larger pile spacing with the number of pile remained constant,the depth and deformation of compression layer below the pile tip will be reduced.The relevant results obtained in this study may provide a reference for future research and engineering design of long pilegroup foundation.

关 键 词：长桩 群桩基础 大比例尺模型 沉降性状 试验 

分 类 号：TU473.1[建筑科学—结构工程]