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为从细观层面探讨桩端附近桩侧摩阻力及桩端承力相互增强效应的力学机理,基于颗粒离散元理论,以PFC2D软件为计算平台,对砂土中单桩的整个加载过程进行了数值模拟分析,直观地描述了在桩基加载过程中桩端附近土体颗粒的速度场、位移场、应力场分布,同时记录了不同加载阶段整个桩长范围内土体的孔隙率变化情况,并对桩端土体的挤密作用和成拱作用进行了系统论证;此外,通过分析桩身侧摩阻力分布情况,着重分析了桩径及土体颗粒刚度对侧摩阻力增强效应的影响。结果表明,在加载过程中,桩端承力和桩侧摩阻力的发挥是相互影响、相互关联的;桩端土体的挤密和成拱作用同时影响桩侧摩阻力增强效应的产生;桩长范围内的土拱增强区并不单一存在,而是呈串联状分布,但以桩端附近土拱作用最明显;随着桩径的增大及桩周土颗粒刚度的增大,桩侧摩阻力增强效应也随之增大。
In order to study the mechanics mechanism of pile-side friction resistance and pile-side bearing reinforcement near pile tip from the microscopic level, based on the particle discrete element theory and PFC2D software, the whole loading process of single pile in sand was carried out Numerical simulation analysis directly describes the velocity field, displacement field and stress field distribution of soil particles near the pile tip during the pile loading process, and records the changes of the porosity of the soil in the whole pile length at different loading stages. In addition, by analyzing the distribution of side friction of pile body, the effect of pile diameter and soil particle stiffness on lateral friction resistance enhancement is analyzed emphatically. The results show that during the loading process, the bearing capacity of the pile end and the frictional resistance of the pile side are mutually influencing and interrelated. The compaction and arching of the soil at the pile end also affect the frictional reinforcement effect of the pile side. The pile Soil arching in a long area does not exist in a single area, but in series. However, the effect of soil arching near the pile tip is the most obvious. With the increase of pile diameter and the increase of soil particle stiffness, Frictional enhancement effect also increases.