Abstract:The parameters of slip surface prove to be crucial and difficult in the study of landslides,especially for many landslides in loose deposit on the Sichuan—Tibet highway. Based on various field investigations,the mechanisms of landslides in these deposits are similar. Hence,a typical study is given in this paper on the mechanical parameters of the slip surface of the102 Landslide on the Sichuan—Tibet highway,and the procedure to obtain these parameters is described. The original sample from the slip surface of the 102 Landslide was obtained and its mechanical parameters were given by triaxial compression tests and back analysis method. By comparision of the results of two procedures,it is shown that back analysis method can determine more accurately the mechanical parameters of the whole slip surface. It is indicated that back analysis is a feasible and effective approach to examine the parameters of the slip surface.