混合集料中颗粒间接触应力的离散元法分析

摘要

采用离散元程序 PFC2D ,对骨架空隙结构型混合集料 PA-13和悬浮密实型混合集料 AC-13的数字试件中的内部应力状态进行了分析,以研究具有不同内部结构组成的混合集料中颗粒间接触应力状态的差异。提出了根据混合集料级配生成二维数字试件的方法。选用 PA-13和 AC-13级配中值的混合集料进行逐级加载的压缩试验,并应用 PFC2D 对生成的对应数字试件进行相同加载条件的虚拟压缩试验,通过调整混合集料数字试件的微观参数,使模拟得到的荷载-位移关系与实测结果间的误差满足要求,从而得到这2种级配混合集料数字试件的微观参数。将已获得的混合集料微观参数进行虚拟的压碎值试验。研究结果表明：在压碎值试验荷载下,PA-13型级配混合集料中颗粒间的法向平均接触力和最大接触力分别是 AC-13型级配混合集料的1.71倍和1.28倍。为保证骨架空隙型混合集料内部结构的稳定性,提出了提高该种混合集料中所用粗骨料的压碎值标准。%The discrete element code,PFC2D,was used to study the contact stresses a-mong aggregates in asphalt mixtures with different internal structural skeleton.Firstly, the method to generate a 2-D digital specimen according to the mixture gradation was put forward.Two gradation mixtures with different internal structural skeleton,PA -13,with skeleton-gap structure,and AC-13,with suspension-dense structure,were de-signed.The compression tests loading step by step were tested on two mixtures.The cor-responding virtual compression tests were conducted using PFC2D.The microscopic pa-rameters of the mixtures were obtained by adjusting their values to make the error be-tween the simulated load-displacement and that of the measured.The virtual crushing value tests were conducted using PFC2D with the obtained microscopic parameters.It was shown that the average normal contact force and the maximum contact force in PA-13 is 1.71 times and 1.28 times higher than those in AC-13.Therefore,the crush-ing value of the coarse aggregate used in skeleton-gap type asphalt mixture should be higher than that used in the suspension-dense type of the asphalt mixture.