| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly accurate ground structure estimating method capable of easily performing measurement even at a narrow site and acquiring highly reliable results. SOLUTION: A vibration generator 11 and detectors 12a-12c are installed on the surface of the ground 5. While changing its oscillation frequency, the vibration generator 11 adds vibration to the ground 5 to detect elastic waves at the detectors 12a-12c. On the basis of this, phase velocity characteristics and the dominant frequency of the ground 5 are computed. Then a hypothetical ground model is created to determine the S-wave velocity of a layer in the vicinity of the surface of the hypothetical ground model on the basis of a phase velocity in a frequency region between a phase velocity peak in the vicinity of the dominant frequency and a phase velocity in a region having a frequency higher than this in the phase velocity characteristics. This computation is repeated as altering parameters of the hypothetical ground model until a dominant frequency and phase velocity characteristics computed on the basis of the hypothetical ground model is approximately matched with those of the object ground 5. In the case of approximate matching, the hypothetical ground model is outputted as an estimated result ground model. COPYRIGHT: (C)2009,JPO&INPIT
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