Abstract: To evaluate the impact of landslide on residential areas and the operational safety of the Lanzhou-Chongqing railway, we carried out field investigation, borehole teleview, mathematical formula calculation and numerical simulation to analyze the formation mechanism of large-scale translational landslide at tunnel exit. According to the result of landslide stability evaluation, sliding distance calculation and numerical modeling, we obtained the risk zoning and put forward some economic and reasonable countermeasures. The results demonstrate that: 1) hydrostatic-pressure and uplift pressure generated by rainfall infiltration in landslide’s back edge induced the landslide instability; 2) the annual probability of landslide sliding over 0.89 m is small than 4.1%, and 2.15 m 0.17%. After the landslide slides over 2.15 m, the landslide will be stable but poses high risk to the residential area in landslide’s front edge and medium risk to the tunnel exit. We suggest taking engineering measures integrating cut off drainage and anti-slide pile. The results are applicable to the prediction and early-warning of translational landslide.

Key words: translational landslide, hazard evaluation, sliding distance, red bed landslide, Lanzhou-Chongqing railway