The Optimal Design Principles and Method of Crushed-Rock Based Embankment in Cold Regions

Crushed-rock based embankment (CRBE) is widely adopted in road construction in cold regions for its active cooling effect. The factors influencing the cooling effect of CRBE mainly include environmental temperatures, the thickness of crushed-rock layer, the thickness of upper refilled layer, the crushed-rock diameter, and the ratio of crushed-rock layer width to height. The optimal CRBE design represents an embankment structure that has the most efficient cooling effect on the roadbed and that protects the frozen soil. This paper discusses five principles in optimal CRBE design and the restrictions to individual factors related to each principle. According to these restrictions and the relationships among the factors, we propose an optimal design method using the air-convection Rayleigh number, Ra, in crushed rocks. Taking CRBE of Qinghai-Tibet railway in Beiluhe area as an example, we calculate the optimal embankment structure using the design method. The results show that the optimal structure is similar to the construction embankment structure designed in light of experiments, which indicates the feasibility of the optimal design method.