中文摘要：

利用离散元法数值模拟了5组试件的双轴试验，得到了粒径对弹性模量、泊松比、强度和裂缝初始应力的影响，分析了20MPa围压条件下粒径与弹性模量、泊松比、强度和裂缝初始应力的关系，以及6种围压与裂缝初始应力的关系，给出了5组试件荷栽作用后颗粒间的接触力和颗粒位移矢量，从细观角度阐释了荷载作用下颗粒的运动模式。模拟结果表明，随着粒径的增大，弹性模量、强度和裂缝初始应力均呈减小的趋势；随着围压的增大，各粒径范围试件的裂缝初始应力呈增加的趋势，并且粒径越大的试件最大接触力和最大位移越大。

英文摘要：

Numerical simulation of biaxial tests were carried out for the five kinds of specimens using discrete element method. The influences of particle diameters on elastic modulus, Poisson＇s ratio, strength and crack-initiation stress were obtained, and the relationships between particle diameters and elastic modulus, Poisson＇s ratio, strength and crack-initiation stress were analyzed under the confining pressure of 20MPa. Besides, the relationships between six confining pressures and crack-initiation stress were analyzed, the contact forces and displacement vectors under loading in five kinds of specimens were given which showed the patterns of particle movement from the microscopic viewpoint under loading. The simulated results indicate that elastic modulus, strength and crack-initiation stress decrease, the crack-initiation Stresses increase with the increase of confining pressures, and the maximum contact force and maximum displacement are larger as the specimens with larger particle diameters.