2005 Fiscal Year Final Research Report Summary
Underground prospecting by artificial seismic wave using discrete Huygens'(TLM) modeling
| Project/Area Number |
16560433
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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 | Akita Prefectural University |
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Principal Investigator |
KAGAWA Yukio Akita Prefectural University, Systems, Science and Technology, Professor, システム科学技術学部, 教授 (10019200)
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| Co-Investigator(Kenkyū-buntansha) |
WAKATSUKI Naoto Akita Prefectural University, Systems, Science and Technology, Assistant professor, システム科学技術学部, 講師 (40294433)
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| Project Period (FY) |
2004 – 2005
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| Keywords | TLM / Discrete Huygens'model / Underground prospecting / Inverse problem / Seismic wave / Visualization / Reconstructed image |
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| Research Abstract |
This work was subject to direct visualization of underground structure by using the back propagation algorithm in the discrete Huygens' (TLM) model.
The wave propagation process was reversely traced by inducing the time reversed reflected impulses observed on the points along the boundaries surrounding the domain, and the back propagation algorithm was easily implemented. The algorithm for underground visualization is that the measured data, which should be collected in real situation, are compared with the simulated data, which is calculated for homogeneous field. However, since the data are only available on the ground surface and on the bore holes of the sides of the field, the data were limited to match the condition in the numerical examinations.
In the result, the upper boundary were only visualized in the case that the data were only available on the ground surface. The addition of the data measured on the bore holes, the boundary of the object was almost completely visualized.
The back propagation algorithm for elastic wave was also considered. If the numbering of the branches in TLM elements were suitable, the scattering matrix for back propagation became identical to the forward scattering matrix. This shows that the same algorithm as that for scalar wave is available for elastic wave.
Those were all examined by numerical simulations for two-dimensional case. The extension into three-dimensional model and the experimental examinations remain for the future tasks.
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