Study On The Design Method Of Spherical Lightweight Materials Subgrade Based On Packing Theory

Subgrade is not only the structural support but also the main bearing body of a road. Besides the weight of pavement and itself, it has to bear traffic loads transferred from pavement. So the strength and stability of subgrade is the basic condit ions to ensure the long term service of a road. However, many common problems in project, such as differential settlement and soft foundation, seriously impact roads performances. Therefore, it’s very important and necessary to search for an efficient and stable technology of subgrade reclamation. Spherical lightweight materials subgrade filling technology is a new type of technology of subgrade reclamation which is fast, stable, light weight, and environmental protection. And the preliminary application of this technology in the fast repair work of urban roads has gained a good effect. However, so far there is no application case in subgrade reclamation and very systematic theoretical research on the application of spherical lightweight materials. Therefore, this art icle research on design method of the spherical light materials subgrade,but also study the stress transfer and mechanical response when spherical lightweight materials piled up, and analyzed its stabilit y so as to put forward a suitable slope form for spherical light subgrade. Major research contents are summarized as follows :First of all, based on the production princip les of foamed cement banking, researching on the mixture ratio of ingredients is using orthogonal experiment design method. O n the basis of previous research, this article performs a series of tests by mixing a certain amount of fly ash and mineral powders into the basic ingredients of foam and cement. And then, this article analyzes the influences of the mount of ingredients on strength of foamed cement banking using orthogonal experiment design method. At last, the best mixture ratio is gained as follows, ratio of water 45%, fly ash 20%, mineral powders 10% and foaming agent 4%.Then, studying contact constitut ive models in Distinct Element method(DEM)- Particle Flow Code(PFC), and the relationship between the micro and macro parameters according to the characteristics of the spherical light materials and the way of contact. And then, combining spherical light materials mechanics performance test results, we identified the contact model and all kinds of parameters required in discrete element simulation.Then, The article performs numerical simulations on different forms of permutation and combination of spherical light materials based on packing theory, and analyzes the stress distribution in different depths of spherical lightweight materials subgrade. Besides, this research analyzed the stress transfer path in the structure from the side of force chain distribution and the contact forces. The contact force of spherical lightweight materials with regular arrangement was measured, and the experimental results are reasonable agreement with simulation results.Finally, simulated by the discrete element method, the analys is of the lateral force distribution of spherical light materials subgrade and different width slope, and determine the slope width which constraints spherical lightweight materials subgrade, and check calculation of the slope stability. According to the slope stability safety factor of the different subgrade height, determining the critical value for setting soil slope suitably. When the subgrade height more than the critical value, the spherical lightweight materials subgrade set reinforced soil retaining wall, and check calculation of reinforced soil retaining wal.