砂土振冲密实的细观颗粒流模拟

对二维颗粒流程序PFC-2D进行二次开发，采用其内置的Fishtank函数库和FISH语言，定义了模拟砂粒和振冲棒的颗粒块，建立了模拟砂土地基振冲加固过程的细观颗粒流模型以及相应的边界条件，研究了振动频率和振冲方向等对加固效果的影响，并对振冲密实前后砂样的孔隙率、颗粒排列等细观结构特征进行了研究。与室内细观模型试验对比结果表明，颗粒流理论能够较好地揭示砂土振冲密实的宏细观变化，振冲后砂土的孔隙率、颗粒排列定向性和有序性等细观特性变化与其宏观密实程度具有一定的对应关系。验证了采用颗粒流理论探索砂土振冲加固的可行性和有效性。

Meso mechanics simulation on vibrocompaction of sand with two dimensional Particle Flow Code

The two dimensional Particle Flow Code (PFC-2D) was introduced to develop a model for simulating the vibrocompaction process in reinforcing the sandy foundation from the view point of meso mechanics. The Fishtank function and FISH language in the Code were used to define the grain of sand, namely clump, and simulate the action of vibratory probe. The boundary conditions were defined correspondingly. The model was applied to study the effects of vibration frequency and direction on the result of reinforcement. The changes of the meso structure characteristics of sand, such as the porosity of sand and arrangement of gains, after vibratory compaction were also studied and verified by the result of physical model qualitatively. It is found that after the vibrocompaction the specific corresponding relationships between the macroscopic compactness of sand and the microscopic characteristics of sand such as porosity and grain orientation etc. exist.