基于颗粒离散元的桩侧摩阻力增强效应研究  

Strengthen Effect of Pile Side Friction Based on Particle Discrete Element Method

作　　者：付茹[1] 周博[1] 李小青[1] 

机构地区：[1]华中科技大学土木工程与力学学院,湖北武汉430074

出　　处：《水电能源科学》2015年第5期127-131,共5页Water Resources and Power

基　　金：国家自然科学基金项目(51278391)

摘　　要：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。The mechanism of strengthening interaction between the pile side resistance around pile tip and the pile-end resistance in micro-mechanics level was analyzed based on the theory of discrete element method （DEM） and simulated numerically by using the particle flow code program （PFCZB）. The velocity, displacement and stress distribution of soil particles around pile tip during pile loading were described in detail. Meanwhile, the soil sample porosity variation under different loading stages was monitored, which demonstrates the compaction and arching effect of pile-end soil. Addition- ally, the influence of the pile diameter and the stiffness of the soil on the strengthen effect were considered. The results show that the pile-end resistance and pile side resistance are interactional, and the compaction and arching effect of pile tip soil are expected to influence the generation of strengthen effect. The soil arching region in the range of pile length is not existed singly, but serially distributed and it is the most obvious and intense around the pile tip. Along with the increase of pile diameter and the stiffness of the soil particles around pile tip, the pile side friction strengthen effect is getting higher.

关 键 词：颗粒离散元 桩侧摩阻力 增强效应 挤密作用 成拱作用 

分 类 号：TU473.1[建筑科学—结构工程]