Abstract：Based on the engineering geological exploration and site investigation of a landslide site induced by roadbed excavation on an expressway，the engineering geological conditions and the deformation characteristics of the landslide are described. It is concluded that the landslide is caused by excavation of the roadbed to decrease sliding resistance and to form a sliding air-face，resulting in the slope sliding along the weak interlayer between the overlying completely and intensely weathered siliceous sandy slate of the Jiangkou Group belonging to the Sinian System and the underlying intensely weathered siliceous sandstone of the Banxi Group. The numerical modeling results of stability indicate that the landslide is caused by low shear strength of the sliding plane and toe excavation，and that the resisting force should be applied to the toe of the slope by backfilling，and that stabilization measures should then be taken before continuing excavation of the roadbed. The shear strength reduction method is employed to compute the variations of the factors of safety with the depth of excavation before and after the slope is supported by anti-slide piles. It is indicated that the factor of safety of slope after stabilization is 1.33 when it is excavated to the designing roadbed；and it can meet the safe demand of the engineering.
