颗粒形态对砂土抗剪强度影响的试验和离散元数值模拟

为研究颗粒形态对砂土抗剪强度的影响,制备了5组不同粒径的球形石英砂和颗粒形态不规则的实验室标准砂,并进行一系列的直剪试验;离散元法能有效地模拟砂土的离散性和不均匀性,基于高性能离散元分析软件MatDEM,通过二次开发,建立直剪试验三维模拟器,对直剪试验过程进行了数值模拟,并对比分析了试验和数值模拟结果。数据表明:(1)石英砂试样的自然休止角与其抗剪强度有着正相关性;(2)球形石英砂较实验室标准砂能更快达到峰值强度,但其值相对较低;标准砂存在着一定的黏聚力;(3)在直剪过程中,直剪盒中部颗粒的位移较周围颗粒不同,形成了明显的剪切带,并且球形石英砂试样的剪切带内颗粒的位移更小;(4)砂土直剪试验中配位数与剪应力有着良好的正相关性。本文结果表明,在相同的荷载条件下不规则颗粒形态的石英砂的抗剪强度要明显大于球形石英砂。

EXPERIMENT AND DISCRETE ELEMENT NUMERICAL SIMULATION FOR INFLUENCE OF PARTICLE MORPHOLOGY ON SHEAR STRENGTH OF SAND

This paper investigates the effect of particle morphology on the shear strength of sand. We prepared five sets of spherical quartz sand and laboratory standard sand with different particle sizes. Based on the high-performance DEM analysis software MatDEM, we established a three-dimensional direct shear test simulator through deeper development. We compared test data with simulated data. The results are summarized as follows. (1)The natural repose angle of quartz sand has a good positive correlation with its shear strength. (2)Spherical quartz sand can reach the peak strength faster than the laboratory standard sand, but its value is relatively low. Standard sand has a certain cohesion. (3)In the direct shearing process, the displacement of the particles in the middle of the shear box is different from that of the surrounding particles, forming a distinct shear band. The displacement of the particles in the shear band of the spherical quartz sand sample is smaller. (4)The coordination number and shear stress have a good positive correlation. The results of this paper show that under the same conditions, the shear strength of quartz sand with irregular particle morphology is significantly greater than that of spherical quartz sand.