摘要
模型槽试验可用于分析打入桩沉桩过程中土体应力、位移和应变场的演化规律,对准确分析打入桩的承载特性至关重要。采用GPU加速三维离散元软件,通过轴对称模型及粒径细化方法,模拟了60°圆心角断面模型槽内砂土中的闭口桩打入过程,着重分析了桩端阻力、土体位移场与应变场的演化趋势,与文献中的试验和有限元模拟结果进行了定性与定量对比,验证了该离散元模型的有效性。主要结论如下:(1)对沉桩过程的离散元模拟,模型尺寸需满足最小槽径-桩径比和桩径-粒径比等尺寸要求,经单元试验参数标定后,可定量分析打桩过程中的土体变形模式;(2)根据沉桩过程中的位移场形态,近桩处土体可分为竖向压缩区、过渡区、径向压缩区,土体最大位移发生在过渡区;(3)桩下方土体主要受到竖向压缩且在桩端处存在应变集中,桩侧土体主要受径向压缩且在桩肩处存在应变集中。模拟结果可结合打桩过程中的土体应力场分布,为打入桩设计方法的改进和承载力计算提供依据。
Calibration chamber tests could be used to analyze the stress,displacement,and strain fields in the soil mass during pile installation,which are crucial for accurately assessing the bearing characteristics of driven pile.The study employed a GPU powered 3D discrete element method(DEM) code to model a 60° fan-shaped calibration chamber test of a closed-end pile penetrated into sand by adopting the axisymmetric assumption and particle refinement method.The tip resistance,displacement and strain fields in sand were analyzed and compared with the experimental and the finite element modeling results from the literature,verifying the effectiveness of the discrete element model.The main conclusions include:(1) The DEM model can quantitatively reflect the deformation pattern and its evolution in sand during pile installation,provided that the requirements on minimum size ratios of chamber-to-pile and pile-to-particle are satisfied.(2) Based on the morphology of the displacement fields during the pile installation,the soil around the pile can be divided into vertical compression zone,transition zone,and radial compression zone,with the largest displacement occurring in the transition zone.(3) The sand beneath the pile tip is mainly under vertical compression,with strain concentration at the tip,while the soil close to the pile shaft is mainly under radial compression,with strain concentration at the shoulder.The numerical results in conjunction with the stress fields around the driven pile provide valuable bases for improving the design methods and bearing capacity calculations of driven piles.
作者
刘晗帆
郭宁
杨仲轩
LIU Hanfan;GUO Ning;YANG Zhongxuan(Computing Center for Geotechnical Engineering,Zhejiang University,Hangzhou 310058,Zhejiang,China;Zhejiang Provincial Engineering Research Center for Digital and Smart Maintenance of Highway,Hangzhou 310058,Zhejiang,China)
出处
《地基处理》
2024年第4期357-367,共11页
Journal of Ground Improvement
基金
国家自然科学基金项目(52078456,52020105003)
浙江省自然科学基金项目(LR23E080001)
浙江大学-浙江交工协同创新联合研究中心项目(ZDJG2021001)
浙江省建设厅项目(2022K073)。
关键词
打桩过程
离散元法
粒径细化方法
位移场
应变场
pile installation
discrete element method
particle refinement method
displacement field
strain field
