粗砂直剪试验与离散元细观机理分析

为了研究了粗砂的临界状态及临界状态下颗粒的运动规律,利用室内大型单剪试验设备以及颗粒流软件PFC2D,对粗砂进行了等体积条件下的单剪试验与数值模拟。室内试验结果表明,粗砂的临界状态摩擦角为36.4°~37.4°,在本次试验条件下,初始正应力、初始相对密实度对临界状态摩擦角基本无影响；数值模拟结果显示,发生较大速度、位移、旋转量的颗粒均位于剪切带范围内,剪切过程接近临界状态时,剪切带内的颗粒累计旋转量分布趋于稳定即在临界状态下,剪切带内颗粒的旋转量非常小；剪切带的宽度约为45倍的平均粒径。

Critical state test and meso mechanism of sand

In order to study the critical state and the movement of particlesof Coarse grained sand, Simple shear tests and numerical simulations were used to investigate the critical state and the movement of particles under the condition of equal volume by using large-scale direct shear test equipment and particle flow software PFC2D.The results show that,there is a critical state in the shearing process. The critical state friction angle of coarse sand is 36.4 ~37.4 and the initial normal stress and initial relative density have little effect on the critical state friction angle under certain condition..The numerical simulation results show that the particles with large velocity, displacement and rotation are all located in the shear band. When the shear process is close to the critical state, the cumulative rotation of particles in the shear band tends to be stable, that is, the rotation of particles in the shear band is very small under the critical state; the width of shear band and the initial normal stress are very small. Size is independent, about 45 average particle size.