Mechanism Analysis And Dynamic Behavior Prediction For The Xieliupo Landslide In Zhouqu County Of Gansu Province

Located in the Zhouqu county,the Xieliupo landslide is a giant long-term creeping landslide which resumes its activity many times.Based on the regional geological background,this thesis analyses the active mechanism by discusssing the forming conditions and influencing factors of the landslide.According to its activity charateristics,the slide mass and the slipzone are regarded as visco-elastoplastic meterials.Three-dimensional finite difference software FLAC3D is used to simulate the landslide deformation with different geological forces such as gravity,fault activity and lateral erosion by Bailongjiang river,to verify their impacts and primary and secondary relations on the landslide activity,and finally to predict the deformation and failure trends of the landslide when intensive rainstorm and earthquake strike.Results are showed as follows:(1)The regional tectonic activities is the key factor which controls the formation of the local topography and the structure of rocks and soils.Irregular gentle slope,weak slipzone and loose slide mass are the special basic accounts for the landslide.Its creep movement are the results of those basic conditions with the fault activity and lateral erosion by the Bailongjiang river.(2)The active mode of the landslide is a compound one where the deposit body slide and crack along the highly weathered zone of the bedrock,the upper part of the slide mass pushes the middle part,and retrogressive failure happens in the front part due to the lateral erosion.(3)The active fault accelerats the creep movement of the landslide.Compared to its activity in the condition of its own weight,the average velocity is increased by 30%with the consideration of the fault activity,which,on the other hand,indicates that the huge volume of the slide mass and the gravitational potential energy carried in the steep topography are the main forces that make the landslide creep.(4)Lateral erosion of the river affects the landslide about 50-70m in the frontal zone,and apparently is not the main factor that causes the creep movement of the landslide.(5)The forecast reseach shows that the second tableland may encountering superficial sliding and local failure in the front when rainstorm as heavy as 100mm in 24 hours hits,and the second tableland will probablely enter the accelaration creep stage and failure in large scale will happen under the strike of great earthquake.