Abstract: The aim of this research is to investigate in landslide’s seepage field, slope deformation and stability affected by tunnel excavation. On the basis of analysing the physical and mechanical and water physical properties of a landslide slope, we simulated the variation of groundwater level and seepage field before and after tunnel excavation using 3D finite difference software Modflow. Furthermore, by employing Geo-Studio, we analyzed the stability and deformation of landslide after water level changed in natural and excavation conditions. Results reveal that the groundwater seepage field changed after tunnel excavation, and obvious water inflow was found at the excavation area. As a result, the groundwater level decreased about 20m and apparent “sinkholes” appeared in the excavation area. The change of groundwater level was mainly reflected in the front edge of landslide. The deformation of 2^# secondary sliding body, which caused the deformation of 1^# secondary sliding body, exacerbated under the combined actions of weakened sliding resistance and increased effective stress. The maximum slope deformation of secondary landslide above the tunnel reached 12.42 cm, but the stability changed slightly.

Key words: landslide, deformation, stability, tunnel excavation, seepage field