In the process of applying construction waste to subgrade,the bearing capacity of the material has an important impact on the service performance of roads.In order to evaluate the meso-mechanical properties of construction waste used as subgrade filler,the bearing ratio test of waste lime-fly ash macadam and soil mixture with different stone contents was carried out by using discrete element software.The strength formation mechanism was revealed by using the discrete element method.The results show that the bearing ratio of the mixture increases with the increase in the stone content and reaches the maximum value when the stone content is 80%.In the bearing ratio test by discrete element simulation,the porosity first decreases and then increases with the increase in the stone content of lime-fly ash macadam soil.When the stone content is 80%,the porosity of the mixture is the smallest,and the best bearing effect can be achieved.As the stone content rises,the particles between the waste lime-fly ash macadam are embedded with each other to form a skeleton structure so that it can effectively bear the load from the penetration rod.