中文摘要：

对不同密实度砂土中的群桩进行室内模型试验，分析了桩土的一些宏观特性，并为进一步进行颗粒流细观模拟提供了必要的参数和宏观依据。在群桩室内模型试验的基础上，建立群桩的颗粒流分析模型，验证了群桩室内模型试验的一些宏观现象，然后进一步从细观角度分析了桩间距以及承台刚度等因素的改变对群桩工作性状的影响，此外还分析了不同位置基桩荷载分布。颗粒流模拟得到的一些结论可以为按沉降控制桩基设计及其工程应用提供理论依据。

英文摘要：

Lab model tests on pile groups in sands with different density are performed, which could provide necessary parameters and macro according for PFC modeling. Then some macro properties of pile-soil are analyzed. On such a basis, the particle flow code analysis models of pile groups are established. Some macro phenomena of lab model tests are verified. The influence of behaviors of pile groups with different pile intervals and cap stiffnesses from the micro level is analyzed. At last, the distribution of load on piles is analyzed. The particle flow code simulation results and the previous conclusions can provide the theoretical references for the design and construction of the settlement-control composite pile.