粒间胶结尺寸对圆形颗粒法向接触响应的影响

Effects of Bond Size on the Normal Contact Behavior of Two Bonded Particles

粒间胶结物的存在改变土体颗粒间接触力的传递方式,因此,显著影响天然结构性土体的宏观力学响应和强度。为了研究粒间胶结的几何尺寸对理想圆形颗粒法向接触力学行为的影响,采用有限元方法模拟了圆形胶结颗粒微观抗压试验,分析了粒间胶结厚度和宽度对粒间法向接触应力分布和抗压强度的影响,并将模拟结果与模型试验进行了对比。结果表明,数值试验所得到的峰前荷载-位移曲线与室内试验结果吻合较好。粒间法向接触应力分布不均,中心大,外缘小。塑性区分布与高应力区不重合,塑性区在胶结物中心和外缘之间产生,逐渐向中心和边缘方向扩展。胶结抗压强度随厚宽比增加而降低,相同厚宽比下抗压强度基本一致。

The presence of interparticle bonds alters the transmitting way of the interparticle forces,and therefore significantly affects the macroscopic mechanical behavior and bulk strength of natural structural soils. In order to investigate the effects of bond size on the normal contact behavior of two idealized circular particles,the finite element method was used for simulating the micro compression test of two granules with a cementation in between. The special focus was placed on the effect of bonding thickness and bonding width on the distribution of the contact stress and the compressive contact strength. The simulation results were compared to available experimental data. The results indicate that pre-peak behavior of load-displacement response depicted in the experiments can be well captured by the numerical simulations. A non-uniform distribution is seen in the contact stresses which reach the maximum value at the center of the bond and decay to the edges. The plastic zone does not coincide with the region of high contact stress. It initiates between the center and the edge of the bond,and grows towards the center and the edge. The compressive contact strength decays with the increase of the bond thickness-to-width ratio,while it insignificantly varies with the bonding thickness and width as long as this ratio remains identical.