Study On A ?(?) Rheology-based Numerical Simulation Method For High-speed And Long-distance Landslides

The high-speed and long-distance landslide is a kind of natural disasters that often occurs in mountainous areas.With strong destructive power,the high-speed and long-distance landslide has a wide influence area and it endangers humans' lives.Thus an efficient and accurate simulation method is needed to help us not only to predict the influence areas for an avalanche,but also to evaluate its risk rating.In the dissertation,an avalanche dynamic model based on the continuum theory and the ?(?)rheology is proposed,and a computation program based on the TVD-MacCormack scheme is developed,thus the flow process of an avalanche can be simulated by using the program.The main innovations of this research are:1.By introducing the ?(?)rheology into the governing equations of the avalanche dynamic model,the MIC avalanche dynamic model is proposed.The model can well reflect the constitutive relationship of an avalanche: it can not only demonstrate the properties of the viscoplastic fluid,but also reflect the frictional properties between particles.By comparing the MIC model,hydraulic model,S-H model and DAN model,it is indicated that these models can be actually put in a nutshell with distinctive coefficients of earth pressure.2.By introducing the Von Mises criterion,Drucker-Prager criterion,Mohr-Coulomb criterion and Matsuoka-Nakai criterion,a method for the determination of the generalized frictional coefficient is suggested.By adopting this method,the physical parameters that are hard to be measured in the ?(?)rheology convert to intensive parameters that are easy to obtain.Thus the applicability of the MIC model are expanded.3.Another form of the MIC model established in a rectangular Cartesian coordinate system is proposed.We can then take advantage of the widely used topographical data,i.e.,digital elevation models(DEM),as a topographical parameter,which helps to overcome the difficulty of measuring the angle of inclination as a topographical parameter,and enables the simulation of avalanches flowing over natural irregular terrain.4.By taking the interactions between particles and water into account,a mixtureavalanche dynamic model is proposed to simulate the flow process of avalanches with high water content.This model can well reflect the influence of liquid concentration by volume on the flow process of the mixture.5.A numerical simulation scheme,i.e.,the TVD–MacCormack scheme,is introduced to solve the governing equations of the MIC model.A program based on this finite-difference method is written,and the flow process of an avalanche can be simulated using this program with high accuracy.The simulation results of laboratory avalanche experiemts and natural avalanche cases verify the validity and the practicability of the MIC model and the developed program.