Study On The Stability Of BaDu Landslide After LongTan Reservoir Impoundment

Badu landslide located at the end part of Longtan reservoir. The impounded water level of reservoir will reach primary stage in july 2007 and the secondary stage by the end of 2009. By the time, the water level of the Badu area will rise 24m and 39m. BaDu station located at the middle part of the landslide. The rise of water level will affect the stability of Badu landslide and threat the safety of Nankun railway, Thereby, it is not only a complicated theory problem but also an important application of engineering that to study the stability effect to the Badu landslide after Longtan reservoir impoundment.Based on the study of environmental and geological condition in landslide area, the paper analysed the geological structure character, deformation or damage mechanism and reactive controlling factors of Badu landslide. Moreover used 3D-Modflow to analysis the groundwater seepage character of the landslide under the rainfall and reservoir impoundment condition, and established the landslide's 3D numerical model (FLAC3D) unified with internal action mechanism and exterior performance which be able to reflect the comprehensive geological - mechanical mechanism - deformation coupling. Then adjust the model by fitting the deformation character of landslide after the Nakun railroad constructed and during storm rainfall condition. Then, the paper simulated the stress field and displacement field of Badu landslide under the reservoir's primary and secondary impounding stage. At last, the paper predicted the deformation and stability of Badu landslide after Longtan reservoir impoundment combine with the results of limit equilibrium method. The study shows:While the impounded water level reaches primary stage, the deformation and damage occur at the forehead of landslide, the pattern represents as slip-uplift, and it is in understable status. The deformation of railroad and sub landslide is little and it is stable in generalWhile the impounded water level reaches secondary stage, the forehead of landslide will be in unstable status. With the impounded water level rising, the deformation range and damage area become bigger and wider and moving to the upper part of landslide. The railroad and sub landslide will be in understable status. The deformation pattern represents as Longitudinal slip. To ensure the safety of Nankun railway, we should take reinforcement measure.