Both seismic velocity tomography and seismic attenuation tomography are applied to in-situ rock testing. Seismic velocity tomography reconstructs a two-dimensional distribution of seismic velocity by using travel time. Seismic attenuation tomography reconstructs a two-dimensional distribution of seismic attenuation characteristics by using first peak amplitude or amplitude spectrum. The seismic data for in-situ rock testing were obtained by the field measurement at the Kamioka mine, Japan. By using the data, distributions of seismic velocity, seismic attenuation characteristics am Q-value are reconstructed. An interpretation of these results shows good agreement with the result of geological observations.


Tomographie de vitesse sismique et tomographie d"attenuation sismique ont ete simultanement appliquees lors d"un test sur roches in situ. La tomographie de vitesse sismique permet de reccnstituer une distribution bi-dimensionnelle de vitesse sismique par la duree de course. La tomographie d"attenuation sismique permet de reconstituer une distribution bi-dirnensionnelle des caracteistiques d"attenuation sismique au moyen de l"amplitude du premier pic ou du spectre d"amplitude. Les donnees seismiques de test sur roches in situ ont pu être obtenues par mesure sur le terrain dans la mine de Kamioka (Japon). Sur la base de ces donnees, nous avons pu reconstituer les distributions de vitesse sismique, les caracteristiques d"attenuatien sismique ainsi que la valeur Q. L"interpretation des resultats des analyses tomographiques montre clairement que ceux-ci recoupent les resultats des observations geologiques.


Sowohl Tomografie von seismischer Geschwindigkeit als auch Tomografie von seismischer, Dampfung werden auf in-situ Felsuntersuchung angewandt. Tomografie von seismischer Geschwindigkeit baut eine zweidimensionale Verteilung von seismischer Geschwindigkeit durch Laufzeit wieder auf. Tomografie von seismischer Dampfung baut eine zwei-dimensionale Verteilung von seismischer Dampfungscharakteristik durch Wellenamplitude Vom ersten Gipfel oder Spektrum der Wellenamplitude wieder auf. Die seismischen Daten fuer Felsuntersuchung wurden durch Felanessung im Kamioka-Bergwerk in Japan gewonnen. Durch die Daten werden Verteilungen von seismischer Geschwindigkeit, seismischer Dampfungscharakteristik und Q-Wert wiederaufgebaut. Eine Auswertung dieser Befurde zeigt eine gute uebereinstimmung mit dem Befund der geologischen Beobachtungen.


Seismic wave is commonly used for obtaining a stratigraphic map and information on the geological character and mechanical properties of the ground. Weak rock, fractured zone, fault, relaxation zone around an excavation and weathered zone near the ground surface can be detected by using seismic velocity, because they often have low seismic velocity compared with surrounding intact rocks. Therefore seismic velocity is used as a major index of rock classification to evaluate in-situ rock mass.

Seismic attenuation characteristics supply also useful information, though they are not used so often as seismic velocity. Seismic attenuation characteristics are represented by attenuation coefficient or quality factor (Q-value). "Weathered and fractured rocks have high seismic attenuation characteristics compared with surrounding intact rocks, therefore they can also be detected by using this characteristics.

Recent advance in computer technology makes tomographic analysis possible. It reconstructs an image of the internal structure of an object from a large number of observation data obtained from the combination of sources and receivers which are arranged to surround the object. Though tomography was originally developed for medical use as X-ray CT, it is applied to underground explorations. Especially, seismic velocity tomography is now available (ISRM 1988).

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