中文摘要：

采用基于离散单元法的颗粒流数值技术对砂土中（无黏聚力）设置就位后单桩在使用阶段的承载特性进行了数值模拟。对应工程中的挤土桩与非挤土桩，按照桩设置的不同方式研究并对比了静压沉桩方式与预埋式两种不同单桩在就位后的工作特性，对两种成桩方式下桩-土-筏板的共同作用特性也略作了比较。分析中，克服传统的连续介质力学模型的宏观连续性假设，研究加载过程中桩体力学行为表现与桩周土体的细观结构参数反应的联系，增进了对桩基工程承载特性与土体渐进破坏演变过程的深入理解。此外，将模型试验与数值模拟结果作了对比分析，桩端荷载-位移曲线特征有较好的一致性。

英文摘要：

Numerical simulation based on DEM was used on bearing characteristics of single pile setup in sand by different methods. With respect to the displacement and non-displacement piles, research and comparison were done for pile setup by methods of static jacking and pre-burying respectively. In addition, pile-soil-raft interaction of abovementioned two types of piles was briefly compared. In the analysis, hypothesis of macro continuity in traditional mechanics of continuum medium was avoided. It was intended to establish the relationship between pile-soil macroscopical response and changes of soil mesomechanical parameters, which would enhance the deeper understanding of characteristics of piled raft foundation and the process of gradual failure of soil. Good consistency of the relationship between pile tip resistance and normalized penetration displacement was obtained from the comparison of results between model tests and numerical simulation.