考虑时间效应的高回填场地不同桩顶荷载基桩受力特性分析  

Foundation Piles with Different Pile Tops Load Considering Time Effect in High Backfill Site Analysis of Mechanical Characteristics

作　　者：白元光 李盛[2] 马莉[2] 何川[3] 王起才[2] 余云燕[2] BAI Yuan-guang;LI Sheng;MA Li;HE Chuan;WANG Qi-cai;YU Yun-yan(Zhengzhou Design Institute of China Railway Engineering Design Consulting Group Co. Ltd., Zhengzhou 450000, China;College of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China;College of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China)

机构地区：[1]中铁工程设计咨询集团有限公司郑州设计院,郑州450000 [2]兰州交通大学土木工程学院,兰州730070 [3]西南交通大学土木工程学院,成都610031

出　　处：《科学技术与工程》2022年第12期4970-4976,共7页Science Technology and Engineering

基　　金：国家自然科学基金(51868041,51668036);甘肃省基础研究创新群体项目(21JR7RA347);甘肃省科技计划(21YF5GA050);甘肃省教育厅产业支撑计划(2021CYZC-28)。

摘　　要：由于基桩在高回填场地的应用不可或缺,考虑在其使用过程中高回填土的蠕变特性对基桩力学特性的影响,利用有限差分软件FLAC3D,并考虑时间效应,对填土厚度为10 m,桩径为1 m,嵌岩深度为3 m的基桩进行桩顶荷载分别为0、0.5、1、2、3、5 MPa的数值模拟分析,得到不同桩顶荷载作用下基桩的受力和变形特征。结果表明:桩周填土沉降随时间呈现先加速增加后逐渐趋于平衡的趋势,不同桩顶荷载作用下桩顶位移随时间的变化速率滞后于桩周填土的沉降变形速率;在桩周填土蠕变初期,桩身最大内力加速发展,而桩端阻力在此段时期的增长并没有出现加速增长;随着填土蠕变进入中后期,桩端阻力加速发展,桩侧摩阻力向桩端阻力转移;待桩周填土蠕变稳定后,桩身最大轴力与桩顶荷载呈现正相关,但是桩身轴力附加值随桩顶荷载的增加而减小;增加桩顶荷载桩,桩端阻力及其附加值也随之增大。该研究可为高填土场地桩基的设计施工提供参考。Due to the indispensable application of foundation pile in high backfill site,considering the influence of creep characteristics of high backfill soil on the mechanical properties of foundation pile during its use process,the finite difference software FLAC3D and the time effect were used to calculate the filling thickness of 10 m and pile diameter of 1 m.The foundation pile with rock-socketed depth of 3 m was subjected to numerical simulation analysis with pile top loads of 0,0.5,1,2,3,5 MPa respectively,and the stress and deformation characteristics of foundation pile under different pile top loads were obtained.The results show that the settlement increases at first and then tends to balance with time,and the rate of pile top displacement changes with time under different pile top loads lags behind the settlement and deformation rate of pile top filling.At the initial stage of creep,the maximum internal force of pile accelerates,but the resistance of pile tip does not increase at this stage.As the creep of fill enters the middle and later stage,the pile tip resistance develops rapidly,and the lateral friction resistance transfers to the pile tip resistance.After the creep stability of the surrounding fill,the maximum axial force of pile is positively correlated with pile top load,but the added value of axial force of pile decreases with the increase of pile top load.Pile tip resistance and its added value also increase with the increase of pile tip load.The study can provide reference for the design and construction of pile foundation in high fill site.

关 键 词：高回填土 蠕变 桩基 桩顶荷载 受力特性 

分 类 号：TU473[建筑科学—结构工程]