摘要
开口管桩贯入过程中会产生复杂的土塞效应,显著影响管桩的沉桩过程与承载特性。考虑到试验方法成本高、周期长、且难以直观反映土塞与管桩的相互作用特性,基于离散元方法开展砂土地基中静压开口管桩沉桩与承载全过程模拟分析。基于室内试验数据对离散元模型参数进行标定,并采用周期性单元复制法生成均质且应力沿深度线性分布的地基模型。基于土体变形特征,揭示管桩中土塞的主动拱与被动拱分布特征。进一步地,结合土塞参数的演化规律,得出土塞增长率(IFR)对土塞状态变化更为敏感,且土塞阻力的发挥趋势与IFR值变化趋势有较高的相似性。基于管桩静载试验模拟,得出静载下开口管桩呈完全闭塞状态,土塞的荷载-位移响应呈弹塑性,并最终建立考虑CPT锥尖阻力、土塞效应、管桩尺寸的静压开口管桩桩端阻力经验计算公式。本文研究成果揭示了土塞的形成演化过程与承载机制,对于考虑土塞效应的开口管桩沉桩阻力预测与承载力计算具有一定参考价值。
The penetration process of open-ended piles will cause complex plugging effects,which further influence the installation and bearing characteristics of piles.Considering the high cost,long period and limitations in reflecting the interaction between piles and soil plugs of the traditional experimental approach,the jacking installation and subsequent loading process of open-ended piles in sand are simulated based on the discrete element method(DEM).The periodic cell replication method is used to generate a homogeneous foundation sample with linear stress distribution.Based on the analysis of the soil deformation characteristics,the characteristics of the active arch and passive arch distribution of the soil plugs are revealed.Based on the analysis of the evolution of soil plugging parameters and plug bearing characteristics,it is found that the incremental filling ratio(IFR)is more sensitive to the plug behavior,and the development of plug resistance shows good consistency with the trend of the IFR value.Also,the open-ended piles are in the fully plugged mode under the static loads,and the load-displacement response of soil plugs is elastic-plastic.Finally,the method for calculating the end bearing capacity of open-ended jacked piles is established by considering the CPT cone resistances,plugging effects and pile size effects.The above results reveal the evolution process and bearing mechanism of soil plugs and can provide reference value for the prediction of installation resistance and calculation of bearing capacity of open-ended piles considering soil plugging effects.
作者
李立辰
刘卓
刘浩
吴文兵
罗仑博
蒋国盛
梅国雄
LI Lichen;LIU Zhuo;LIU Hao;WU Wenbing;LUO Lunbo;JIANG Guosheng;MEI Guoxiong(Faculty of Engineering,Engineering Research Centre of Rock-Soil Drilling&Excavation and Protection,Ministry of Education,China University of Geosciences,Wuhan 430074,China;Institute of Science and Technology,China Three Gorges Corporation,Beijing 101100,China;Ocean College,Zhejiang University,Zhoushan 316021,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2024年第7期1471-1480,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(52178371,52308383)
湖北省自然科学基金青年项目(2023AFB008)
中国博士后科学基金面上项目(2022M712964)。
关键词
开口管桩
土塞效应
离散元法
桩端阻力
open-ended pile
plugging effect
discrete element method
end bearing capacity
