| Project/Area Number |
03650413
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
KISHINO Yuji Tohoku Univ., Dept. of Civil Eng., Associate Professor, 工学部, 助教授 (00005448)
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| Co-Investigator(Kenkyū-buntansha) |
NIISEKI Shigeru Tohoku Univ., Dept. of Civil Eng., Research Associate, 工学部, 助手 (30005524)
NAKAGAWA Masami Tohoku Univ., Dept. of Civil Eng., Research Associate, 工学部, 助手 (80198043)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1992: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Micromechanics / Debris Flow / Flowing Mechanism / Simulation / Granular Element Method / Pore Pressure / Two Phase Behavior / Eigen-Value Analysis / シミュレ-ション |
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| Research Abstract |
The debris flow is a mechanical phenomenon which is very hard to analyze, because it exhibits the solid-like behavior as well as the fluid-like behavior. In this research project, an investigation with GEM (granular element method) was attempted as a micromechanical approach to the debris flows. The main characteristic of GEM is that it utilizes the stiffness matrix unlike other distinct element methods. Although this research has not yet reached the quantitative evaluation of real phenomena, it presents a contemplative model to clarify the complicated mechanism of debris flows.
The first part of this research is the presentation of eigenvalue analysis for granular assemblies. The eigenvalue analysis, which is usually applied to the strain-localization analysis in solid continua, was developed so as to be able to handle discrete media. A new idea called the eigen-mode expansion was also presented. A simple example applied for a shearing test of granular model shows the effectiveness of this approach.
The second part of this research is directed to the modeling of pore-water pressure which is inevitable in analyses of debris flows. A stability analysis of granular slope with pore water gives an important hint for the flow-initiation mechanism of debris flows. Considerations through the calculation of coordination tensor and the eigenvalue analysis were also presented. From observation of the results obtained by the eigenvalue analysis, it was found that the flow-initiation mechanism which reflects fluid-like behavior of debris flow is quite different from the strain-localization mechanism in granular assemblies.
The last part of this research is the presentation of a new simulation model to analyze the transitional phenomena of granular assemblies which behave as solids and as fluids. The method will be called Dynamical Granular Element Method. The application to a dynamical behavior of granular slope demonstrates the effectiveness of this new method.
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