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| | Abstract | | The purpose of this study is to develop the data acquisition system to explore accurately the fracture, water pass way, in hard rocks. We make hard rock model, L2.5m, D0.6m, H2.5m, including horizontal fracture. The aperture is 0.5 mm by stacking two blocks of granite. Two boreholes are drilled trough the fracture, which is located 1 m from the top of the model. The distilled water or the high viscosity fluid is saturated in the fracture. The acoustic tomography method was conducted using the rock model. The interval of measurement points is 10cm, and the frequency of the transmitter ranges from 10kHz to 50kHz. P-wave velocity section and attenuation section were analyzed by 2D inversion. As the result, the fracture position was explored clearly in the attenuation section, however it was very difficult to locate the fracture in the velocity section. And fracture saturated by high viscosity fluid is detected more clearly than the case of distilled water. It is indicated that the acoustic tomography is more available to explore the fracture in hard rocks than conventional geophysical exploration methods. |
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