摘要
采用人工制备湿陷性黄土作为模型试验相似材料,进行2×2群桩基础浸水模型试验,对桩周土体湿陷变形规律和桩基础荷载传递特征进行分析。结果表明:土层浸水后,随浸水时间的持续,湿陷变形量-浸水时间关系曲线可划分为:初期平缓段、浸水陡降段、中期平缓段和停水后平缓段。随湿陷深度的增大,桩侧负摩阻力自上而下发展,中性点深度逐渐下移。停水稳定后,中性点深度比为0.7。在大厚度湿陷性黄土地基中,当湿陷性黄土层下限深度采用室内试验确定时,同时考虑桩顶承受工作荷载,浸水后负摩阻力的中性点深度比可参考建筑桩基技术规范取值。当土层湿陷变形处于浸水陡降期时,桩侧负摩阻力迅速发展,下拉荷载和桩端荷载增大,导致群桩基础沉降也逐渐增大,土层的湿陷与桩侧负摩阻力、群桩基础沉降的发展呈现出同步趋势。
The artificially prepared collapsible loess is used as the similar material to carry out 2×2 pile group model tests under water immersion.The change law of collapsibility deformation and the load transfer mechanism are analyzed.The results show that with the increase of soaking time,the relationship between the cumulative collapse settlement and the time mainly includes the initial gentle section,immersion steep drop section,medium gentle section and gentle section after water cut.With the increase of collapse depth,the negative frictional resistance develops from top to bottom,and the depth of neutral point moves down gradually.When the settlement achieves stability,the neutral point depth ratio is 0.7.In large-thickness collapsible loess,when the depth of collapsible loess is determined by the laboratory experiments,and considering the working load on pile top,the neutral depth ratio of negative friction resistance can be determined by the recommended value of technical specification for building pile foundation.In the steep drop period of water immersion for collapsible deformation of soil layer,the negative friction resistance acting on the pile increases rapidly,which leads to the increase of downward load and pile end load and gradual increase of the settlement of pile foundation.Collapse of soil layer presents a synchronous trend with the negative friction of pile side and the occurrence and development of pile foundation settlement.
作者
张延杰
王旭
梁庆国
蒋代军
李建东
ZHANG Yan-jie;WANG Xu;LIANG Qing-guo;JIANG Dai-jun;LI Jian-dong(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Key Laboratory of Road&Bridge and Underground Engineering of Gansu Province,Lanzhou 730070,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2021年第S01期219-223,共5页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51868038,41662017)
兰州交通大学“天佑青年托举人才计划”基金项目
关键词
桩基工程
湿陷性黄土
群桩
负摩阻力
模型试验
pile foundation engineering
collapsible loess
pile group
negative skin friction
model test
作者简介
张延杰(1985—),男,博士,副教授,主要从事土工理论及桩基础方面的教学和科研。E-mail:shuizhongdelantian@163.com
