| Project/Area Number |
16360281
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | TOKYO UNIVERSITY OF SCIENCE |
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Principal Investigator |
SHINOZAKI YUZO TOKYO UNIVERSITY OF SCIENCE, FACULTY OF ENGINEERING, PROFESSOR, 工学部, 教授 (80026236)
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| Co-Investigator(Kenkyū-buntansha) |
TADA TAKU TOKYO UNIVERSITY OF SCIENCE, FACULTY OF ENGINEERING, RESEARCH ASSOCIATE, 工学部, 助手 (40349840)
HORIKE MASANORI OSAKA INSTITUTE OF TECHNOLOGY, FACULTY OF ENGINEERING, PROFESSOR, 工学部, 教授 (80221571)
CHO IKUO NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY, INSTITUTE OF GEOLOGY AND GEOINFORMATION, RESEARCH SCIENTIST, 地質情報研究部門, 研究員 (10328560)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥9,400,000 (Direct Cost: ¥9,400,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2005: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2004: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | MICROTREMORS / GEOPHYSICAL EXPLORATION / STRONG-MOTION PREDICTION / SEISMIC ARRAY / SURFACE WAVES / RAYLEIGH WAVES / LOVE WAVES / 強振動予測 / 微動 / 地震波位相速度分散曲線 / 交通振動 / 地下地盤構造 |
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| Research Abstract |
In order to realize strong-motion prediction of fine resolution in urban areas, it is desirable to establish simple, economical techniques to explore subsurface soil structures on local scales. The SPAC method is one of such techniques that are considered most promising in recent years. This method consists in measuring microtremors (ambient vibrations) with a circular array of seismic sensors, and in evaluating phase velocity dispersion curves of surface waves by analyzing the records. Once the dispersion curves are known, it becomes possible to indirectly evaluate subsurface soil structures and vibration characteristics of soil.
We have found out that, by shedding a new light on the basic theory of the SPAC method, it was possible to devise a number of new circular-array methods of microtremor exploration, and in fiscal 2004 and 2005, we concentrated our efforts on elaborating their theory and making them viable methods for practical use. Among others, two new techniques, which we have named the "Two-Radius method" and the "Centerless Circular Array (CCA) method," respectively, deserve special attention, the former because of its methodological originality that consists in cancelling out all information on Rayleigh waves and extracting information on Love waves alone, and the latter because of its validity over an extremely wide range of wavelengths.
In fiscal 2006, we acquired field microtremor records using "miniature" seismic arrays, with radii on the order of 1 meter, and examined whether the different analysis methods could be validly applied to them. It was shown that, by using the CCA method, phase velocities of Rayleigh waves could be inferred with sufficient accuracy up to wavelengths worth about 100 times the seismic array radius. This finding points to the new possibility of inferring deep subsurface soil structures with relative ease, even in urbanized areas with a dense population of artificial obstacles.
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