A Finite Difference Method Based Numerical Model For The Rapid Long Run-out Landslide Of Flow-type

The rapid long run-out landslide of flow-type is a catastrophic natural hazard,which has a huge destructive power can damage all infrastructures and lives in its region of influence.The formational mechanism of the landslide is rather complex,and since that it catches much of focus from researchers all over the world.To give a reliable assessment for the susceptibility,information such as covering area,velocity,and thicknessare necessary.Numerical simulation is the most efficient tool to obtain these indexes,and plenty of numerical models have been developed currently.There are two types of numerical models for the simulation of the landslide based on the medium of sliding mass,one is the Continuous Medium Model(CMM),and the other one is the Discrete Medium Model(DMM).The CMM is suitable for the simulation of the propagation process of the rapid long run-out landslide of flow-type.The Finite Difference Method(FDM)is a numerical method widely applied in the computational fluid mechanics,which have been implemented in the simulation of the landslide for a long history.As a classic numerical method,many experiences on the method have been accumulated these years.The most significant merit of the FDM is embodies by the time-saving and simple properties of it,so in this paper it is chosen as the basic numerical method to be used.Mathematic model and difference model for landslide of 3 dimensional are deduced carefully,and the reasons for the implements of particular items are discussed.In the model,centrifugal effect is taken into account to reflect the influence of irregular topography.A VB program is then made based on the difference model.To test the numerical stability and property of the model,the Dam Break test is simulated to compare with the theoretical solution.The result shows that the model used in this paper can reflects the flow-type motion properly,and shows a good agreement with the theoretical solution.Another numerical test of landslide slides over a surface of waving shape is conducted.The result shows that landslide without centrifugal effect moves much further,while landslide with centrifugal effect is bound by the waving surface like the real case.Two real cases of the landslide are studied in the end.One is the Dabaozi landslide in Shaanxi Province,at the north edge of the loess tableland of Jingyang County.The other one is Dagou landslide in Gansu Province,a landslide induced debris flow in Dagou valley.The characters of the two cases are quite different,but both reveal flow-type characters.The model proposed in the paper can catch most details of the landslides,and the simulation results show good agreements with the measurement.The model proposed in the paper has good numerical stability and properties,and can be used in the prediction of the susceptibility for the rapid long run-out landslide of flow-type.