Abstract: In order to solve the problem of cutting slope instability caused by reactivation of old landslides,taking a instable cutting slope along with expressway as an example, the cutting excavation and the effect of advance support was studied with the help of numerical analysis. The main conclusions and suggestions are as follows:1) The overall stability of the slope can be improved by the wide platform excavation mode. However, the wide platform excavation mode is not conducive to the stability of the old traction landslide with the existence of weak structural plane, weak interlayer and sliding zone with expansion properties. Advance support must be adopted, such as anchor rope, anti-slide pile and so on, and unloading measures also should be taken urgently when necessary. 2) Anchor cable pre support can effectively restrain the cutting deformation, so effective measures should be taken to improve the tensile strength of anchor, which is arranged at slope toe or to apply pre-stressing force. 3) In advance anti-slide pile supporting, attention should be paid to the design optimization of pile position, pile length and pile spacing. Anti-slide pile should be anchored by bolts, and the sliding zone in front of the pile should be used for pre grouting; and it is necessary to arrange multi row anti-slide piles along the main sliding direction of the old landslide, or to adopt the h-type pile design.

Key words: old landslide, cutting slope, excavation, anchor cable support, anti slide pile support