Abstract：Considering the phase-change and influence of the global temperature rising，the computed simulation of the temperature field of the L-typed retaining wall only in Qinghai—Tibet Railway has been carried out using numerical calculation method. Through establishing finite element model of subgrade temperature field，the suitable boundary condition，the initial condition and the heat computation parameter are selected；and the variation situations of ground temperature during the future 10 years in Beilu River test section are analyzed and they are compared with monitored two-year actual ground temperature. The calculated thawing depth and the measured data are basically consistent. The result shows that the characteristics of ground temperature response lagging to the temperature change. It also displays that the proposed model is reliable. The computed result can be adopted by other engineering practices. Future 10-year computed results indicate that the maximum thawing depth(or permafrost table) is not developed. It is explained that the frozen soil has already formed to a new balance；and permafrost table is stable. This result can be considered for Qinghai—Tibet Railway. It is forecast that the ground will finally be of stable thermal equilibrium condition. It indicates that the kind of flexible L-typed retaining wall applied to permafrost region is acceptable.
