黄土地基H-U组合荷载作用下扩底桩承载特性研究  

Study on the Bearing Characteristics of Belled Pile Under Combined H-U Load in Loess Soil

作　　者：陈阳[1] 吴武强 訾凡 耿芳杰 王伟伟 赵宇飞[4] CHEN Yang;WU Wuqiang;ZI Fan;GENG Fangjie;WANG Weiwei;ZHAO Yufei(Institute of Geotechnical Engineering,Xi'an University of Science and Technology,Xi'an 710048,China;China Nonferrous Metals Industry Xi'an Survey,Design and Research Institute Co.,Ltd.,Xi'an 710061,China;China Railway 14th Bureau Group Construction Engineering Co.,Ltd.,Jinan 250101,China;China Institute of Water Resources and Hydropower Research,Beijing 100038,China)

机构地区：[1]西安理工大学岩土工程所,陕西西安710048 [2]中国有色金属工业西安勘察设计研究院有限公司,陕西西安710061 [3]中铁十四局集团建筑工程有限公司,山东济南250101 [4]中国水利水电科学研究院,北京100038

出　　处：《应用基础与工程科学学报》2024年第4期972-983,共12页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(52008338);中国水利水电科学研究院水利部水工程建设与安全重点实验室开放基金项目(IWHR-ENGI-202305);陕西省博士后科研项目(2023BSHYDZZ138)。

摘　　要：为研究水平-上拔(H-U)组合荷载作用下荷载倾角和扩径比对扩底桩抗拔承载特性的影响,开展了黄土地基中4组荷载倾角θ(0°、15°、30°、60°)和2组扩径比λ(1.5、2.0)下的抗拔承载特性试验.对比分析了不同工况下的荷载位移曲线、桩身应变和桩侧土压力分布规律,探讨了扩底桩抗拔承载性能与荷载角度、扩径比之间的关系.进一步探究了荷载顺序、长径比和抗剪强度等因素对H-U组合荷载下破坏包络线的影响.研究结果表明:当θ=0°时,λ由1.5提高至2.0时,扩底桩的极限承载力T_(λ=2)较T_(λ=1.5)提高了126%;随着荷载倾角的增加,当θ>30°时,λ增大对扩底桩的极限承载力提高效果降低.H-U联合荷载作用下桩体承载力随着长径比(L/d)和土体抗剪强度的增加而增大,扩底桩主要通过扩大端克服桩周土体抗力,从而提高单桩抗拔承载性能.To study the influence of inclination angle and expanded diameter ratio of inclined uplift load(H-U)on the pull-out bearing characteristics of belled piles in loess area,pullout tests of 4 load anglesθ(0°,15°,30°,60°)and 2 expanded diameter ratiosλ(1.5,2.0)were performed.The load displacement curves,strain variation,and distribution of earth pressure under different engineering scenarios were compared according to the tests results.In addition,the relationship between the pull-out bearing performance of belled pile with respect to the load inclination and expanded diameter ratio were explored.Further,the influential factors such as load sequence,length to diameter ratio,and shear strength on the failure envelope under H-U combined loads were investigated.Results indicate that the ultimate bearing capacity T of the belled pile increased by 126%withλincreases from 1.5 to 2.0 whenθ=0°.With the increase ofλ,increment of the ultimate bearing capacity of belled pile decreased.The ultimate bearing capacity under H-U combined load increases with the length to diameter ratio L/d and the shear strength of the soil.Soil resistance around the enlarged part contributes to the uplift bearing capacity of the pile.

关 键 词：黄土 扩底桩 组合荷载 承载特性 包络线 

分 类 号：TU473[建筑科学—结构工程]