Abstract: The retrogressive landslide occupies a considerable proportion among expressway landslides in the mountain area. The reinforcement projects often cost enormously and the environment around is usually damaged severely. Taking a certain expressway retrogressive landslide for example, through approaches of geological survey, deformation investigation, stress-strain behavior analysis and numerical modeling, the failure mechanism is confirmed as follows: (1) the loss of resisting key block is caused by slope foot excavation, shear strain softening is induced by stress concentration; (2) physico-mechanical properties alternation of the rock and soil mass are remolded by the surface rainfall and groundwater; (3) tensile cracks are fromed deformation incompatibility and its expanding backward. The monitoring results show that the applied combined reinforcement measures work well. The geological characteristics of excavation-induced retrogressive landslides are discussed. A principle that “the safety factor should be calculated by section should use to evaluate retrogressive landslide; the reinforcement of the whole landslide should be controlled by the predetermined safety factor; while the reinforcement of landslide rear should be controlled by displacement.

Key words: retrogressive landslide, landslide boundary, reinforcement measures, displacement control