Author(s): Motohiko Hakuno
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Abstract: Landslides and rock avalanches frequently occur after strong earthquakes in mountainous regions. The landslide of the earthquake flows as a rock avalanche that has little moisture during the initial stage of collapse but obtains water content from outside downstream and in many cases becomes a debris flow with much water. It is difficult to analyze those behaviors by procedures such as the Finite Element Method (FEM) in which 1 a medium is assumed to be continuous. Consequently, numerical methods in which the objective medium is considered an assembly of many independent small elements have been developed to deal with that problem1,5>. The Distinct Element Method (DEM) originated by Cundal l1> is one such method that is based on the assumptions that each individual element satisfies the equations of motion and that the transmission of force between elements follows the law of action and reaction. The equations of motion for each element solved by step-by-step numerical integration in the time domain. The DEM allows us to analyze numerically problems in which the contact between elements changes at any moment and compensates for the weak points of continuous analysis methods. Because this method will be realistic only with major improvements to computer systems, there are many problems still to be solved. A medium consisting of independent discontinuous elements has some continuity due to the bonding effect of the pore material. Iwashita and Hakuno3,. Proposed an additional nonlinear spring (Fig.1) which represents the effect of clay between gravels and made a DEM analysis of the dynamic behavior of ground.
Year: 1993