根键桩承载机理和沉降特性数值分析  

Numerical Analysis on Bearing Capacity and Settlement Characteristics of Root Piles

作　　者：刘刚[1] 夏理巧 余竹 祝凤金 刘红岩[4] LIU Gang;XIA Li-qiao;YU Zhu;ZHU Feng-jin;LIU Hong-yan(Research Institute of Highway,Ministry of Transport,Beijing 100088,China;Wenzhou Expressway Investment Co.,Ltd.,Wenzhou Zhejiang 325000,China;Anhui Transportation Holding Group Co.,Ltd.,Hefei Anhui 230088,China;School of Engineering&Technology,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]交通运输部公路科学研究院,北京100088 [2]温州市高速公路投资有限公司,浙江温州325000 [3]安徽省交通控股集团有限公司,安徽合肥230088 [4]中国地质大学(北京),工程技术学院,北京100083

出　　处：《公路交通科技》2022年第7期84-89,105,共7页Journal of Highway and Transportation Research and Development

基　　金：国家重点研发计划项目(2017YFE0103000);中央级公益性科研院所基本科研业务费项目(2021-9052a)。

摘　　要：根键作为根式基础的重要组成部分,在提高根式基础竖向承载力和沉降控制能力中发挥着重要作用。在根式基础中将根键的作用单独考虑,针对根键的破坏形式和根键对桩周土体的作用进行了深入研究。结合试桩的现场试验验证了数值模拟的结果与现场试验的结果规律一致,可采用数值模拟手段研究根键桩和根键的作用机理。利用数值模拟手段分析了根键在不同长度、中心层间距和不同布置位置时的受力和变形特性,以此来反映根键与土体的作用效果和根键的破坏模式,揭示根键对桩周土体的作用。将根键视作受弯弹性地基梁,给出了Winkler模型下根键受力理论解。结果表明:根键桩的承载性能和沉降控制性能远优于普通桩,更适用于滨海深厚软土地区的工程实践;根键在桩顶竖向荷载作用下,其变形和受力分布形式类似于受弯Winkler弹性地基梁模型;当桩顶承受较大荷载时,根键与桩身连接处易发生剪切破坏,故根键桩施工过程中,要保证根键的强度,避免根键失效;根键层间距越小,根键与根键层间土体的耦合作用越强,同时根键层间土体向下位移量也越大;根键影响范围内的土体主要发生剪切破坏,根键能充分调动桩周土体共同发挥承载作用。As an important part of root foundation, root key plays an important role in improving the vertical bearing capacity and settlement control ability of root foundation. Considering the action of root studs separately in the root foundation, the failure mode of root studs and the effect of root studs on soil around piles are studied in depth. According to the field test of test piles, it is verified that the numerical simulation result is consistent with the field test result, so the mechanism of root pile and root stud can be studied by numerical simulation. The stress and deformation characteristics of root studs with different lengths, different spacings between central layers and at different positions are analyzed by means of numerical simulation to reflect the effect between root stud and soil as well as the failure mode of root studs, and reveal the action of root studs on soil around piles. Regarding the root studs as a flexural elastic foundation beam, the theoretical solution of the stress on root studs in the Winkler model is given. The result shows that(1) the load-bearing and settlement control performance of root piles are much better than those of ordinary piles, and root piles are more suitable for engineering practice in coastal deep soft soil areas;(2) the deformation and stress distribution of root studs under the vertical load of pile top are similar to those of the flexural Winkler elastic foundation beam model;(3) when the pile top bears large load, shear failure is easy to occur at the connection between root stud and pile body, so the strength of root stud should be guaranteed to avoid root stud failure in the process of root pile construction;(4) the smaller the interlayer soil distance between root stud layers, the stronger the coupling between root studs and the interlayer soil, and the greater the downward displacement of the interlayer soil;(5) the soil within the influence range of the root studs mainly suffers shear failure, and the root studs can fully mobilize the soil around the pi

关 键 词：桥梁工程 承载机理 数值模拟 根键 沉降特性 

分 类 号：TU473[建筑科学—结构工程]