2006 Fiscal Year Final Research Report Summary
Development of six-dimensional numerical testing simulator of granular specimen and its applications
| Project/Area Number |
16560428
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geotechnical engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
KISHINO Yuji Tohoku University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (00005448)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Granular Media / Granular Element Method / Sliding Contact Tensor / Dissipative Stress Tensor / Plastic Flow Rule / Newmark b Method / Dynamic Simple Shear / Reynolds Stress |
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| Research Abstract |
In this research, the granular element method proposed by the author was developed as static and dynamic simulators to perform numerical element tests of granular specimen. As the granular element method uses iteration procedure to get the static or dynamic equilibrium condition, it secures high accurate results compared with the DEM code. With the developed simulators, the author studied the plastic flow rule and the dynamic simple shear characteristics of granular media.
By applying the static simulator, the author proposed the statistical representation of slippages in granular specimen and derived the plastic flow theory. The distribution characteristics of sliding planes in a granular specimen were represented by the average of fourth order tensor products of unit outward normal vectors of sliding planes. The new statistical quantity will be called the sliding contact tensor. On the other hand, the dissipative energy at sliding contact point is statistically expressed by a linear c
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ombination of the incremental strain components with a coefficient tensor called the dissipative stress tensor. The dissipative stress tensor includes the sliding contact tensor in natural manner. Alternatively, the dissipative energy is expressed by a double inner product of stress and plastic strain. By equating these two expressions of dissipative energy, we obtain a constraint condition. Under this constraint condition, by maximizing the dissipative energy, we can determine the direction of plastic incremental strain, which is in good agreement with the direct simulation results.
By applying the dynamic simulator, the parametric study of dynamic simple shearing under the wide range densities and sharing velocities show the behaviors as the cohesive flow and the collisional flow, depending upon the granular density. To investigate the dynamic activity, the author derived the Reynolds stress from the microscopic point of view. The amount of Reynolds stress increased rapidly with the decrease of density, and the magnitude of Reynolds stress for high granular density had the tendency that it is equal to the shear stress observed at the boundary. Less
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