Abstract: Slope cracking is an important stage in the entire process of a landslide formation failure. The soil strength reduction at the slope due to the precipitation and/or the disturbance of the construction was numerically simulated with the commercial software ABAQUS by using strength reduction method. In the analysis, a plastic yielding zone in the slope was obtained and the factors that might induing the slope cracking at the tunnel portal were investigated. The results show that: the distribution characteristics of the plastic strain zone in the soil mass after the finite element strength reduction are in good agreement with the soil cracking characteristics in the slope, and the plastic strain zone of the slope soil can be used to analyze the cracking problem of the slope; with the tunnel portal advancing forward, the plastic strain zone of the slope soil will change, especially when the tunnel face passes through the plastic strain zone; the plastic strain zone of the slope soil will change. The plastic zone of slope soil has not developed to the vault area of the tunnel, which indicates that the influence of tunnel construction on the soil cracking area of the slope far away from the tunnel face is limited; the left side slope will be in an unstable state with high landslide risk, so it is necessary to monitor its deformation, but the sliding surface will not affect the tunnel vault area.

Key words: slope cracking, strength reduction, plastic strain zone, landslide, stability