Study And Program Development Of Displacement Control Discrete Element Method And Its Application In Dynamic Simulation Of Landslide

This study is funded by the Natural Science Foundation of Hunan, China, on"Full-course numerical study on landslide using discrete element method"(Grant No.05JJ30075). According to the purpose and scope of the study, the research work is carried out on the fields of numerical algorithm of discrete element method, corresponding computer program development and applications of dynamic numerical simulation of landslide.Landslide is a kind of geological disaster which is difficult to forecast but has a high frequency. By means of discrete element method and computer simulation, inherent mechanism of landslide is studied. The simulation results will be presented in graphics instead of traditional statistics by using visualization technology. With the dynamic representation of the full course of landslide, the dynamic mechanism of landslide is further studied.In this paper, in view of some current problems of discrete element method, such as judging the range of calculating parameters, displacement control solution is proposed. The displacement control solution is based on dynamic relaxation of discrete element method, and it successfully solved the problem of unstable result caused by unreasonable time-step interval during calculating. Time-step interval is obtained by calculating the displacement of the element. The results show that the judging of time-step interval is comparative easy than before, and this method also improves the calculating precision and efficiency and, to some extent, settles the problem of too much overlap between blocks caused by the unreasonable parameters. Meanwhile, by some examples studied, the reasonable range of stiffness coefficient has been obtained during the discrete element calculating.The computer program is developed for landslide blocks stability analysis based on the discrete element method, including the pre- and post processors for results presentation in graphics mode. The pre-processor consists of drawing and showing model, inputting parameters and applying constraints. The post processor shows the final results such as the contacting information between blocks, stress field ,displacement field and dynamic displaying images of the destructing process of landslide. The program route and algorithm is introduced by attaching some flow charts.There is a large number of Visual C + + functions and variables in the computer code. In this paper, some key codes are explained in detail from the perspective of programmer and data structure.A practical slope, which is 220m in height from V-132 to V84, located in A zone of east side of Lion mountain of Wuhan Daye Iron mine, is simulated and analyzed by the program. The results obtained from the discrete element method of displacement control analysis coincide well with the actual monitoring. The example results prove that the presented method has a broader application range both in landslide simulation and some similar nonlinear and large deformation geological problems.