细砂路基碾压密实的颗粒流模拟与试验验证

Discrete Element Method Simulation and Experimental Verification on Roller Compaction of Fine Sand

利用PFC2D软件建立了模拟细砂路基密实过程的颗粒流模型,研究了碾压方式、静碾作用力大小、振动碾压遍数对细砂密实情况的影响,并通过现场试验进行了验证.结果表明,细砂的碾压机理主要包括颗粒挤密和长轴定向;静碾作用下,细砂孔隙率减小值沿深度方向无明显差异,且颗粒长轴的方向性改变不显著;振动碾压时,细砂上部孔隙率的减小较静碾更为明显,且颗粒长轴与水平方向夹角小于30°的颗粒数量增加了33.3%;增加振动碾压遍数可使细砂上部的孔隙率进一步减小,但5遍后增加振碾次数对密实度的提升效果不再明显;模拟结果与现场试验结果较为吻合,颗粒流模拟结果可供实践参考.

The discrete element method(DEM)models were established by using two-dimensional particle flow code(PFC2D)to simulate the fine sand compaction process,and the influencing factors,including compaction method,static force and vibrating compaction number,were investigated by using DEM and validated by field experiments.It is shown that the compaction of fine sand can result in the densification of particles and the horizontal orientation of long axis.For static compactions,the difference of densification effect in depth and the rotation of long axis are comparatively insignificant.For vibrating compactions,the decreases of porosity in the upper sands are more pronounced,and the number of particles with horizontal angle of deviation less than 30°increases by33%.The increase in the number of vibration compaction can lead to the decrease in the porosity of the upper sands,however,it is not effective after fifth vibrating compaction.The simulation results are in good agreement with the experimental results, which verifies the feasibility and effectiveness of PFC.