• The Journal of Engineering Geology
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• v.23 no.3
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• pp.235-246
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• 2013

P-wave velocity was measured by the low frequency flaw detector in order to analyze the weathered state of a halo stone Buddha, Unju temple, Hwasun, Korea. By the results of laboratory tests on a fresh acidic tuff with the same rock of a halo stone Buddha, average absorption, average P-wave velocity, and average uniaxial compressive strength were 5.38%, 4,008 m/s, and 70.1 MPa, respectively. The results correspond to moderately strong rock. Average P-wave velocity of a halo stone Buddha measured by the low frequency flaw detector was 2,257 m/s in the left zone, 3,437 m/s in the right zone, and 2,802 m/s overall. Weathering index of a halo stone Buddha was 0.45 in the left zone, 0.21 in the right zone, and 0.33 overall. Comparing the results of a halo stone Buddha with them of laboratory tests, weathered state of a halo stone Buddha was analyzed highly weathered state in the left zone and moderately weathered state in the right zone. Furthermore, it suggests that the left zone of a halo stone Buddha was affected weathering more than the right one. Overall a halo stone Buddha corresponds to moderately weathered state of weathering degrees. In conclusion, it is considered that low frequency flaw detector may be applicable as a valuable method on analyzing the P-wave velocity of the stone cultural heritage with an irregular surface.

• The Journal of Engineering Geology
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• v.27 no.1
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• pp.51-58
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• 2017

The purpose of this study was to quantitatively evaluate the state of rocks in load steps by using the low-frequency ultrasonic flaw detection method. The initial Vp-velocities measured with a CND tester were in the order of Z-axis < X-axis < Y-axis, with 1687.5 m/s along the X-axis, 1690.7 m/s along the Y-axis, 1548.3 m/s along the Z-axis, and an average of 1642.2 m/s. The overall average of the Q vlaues, measured with a Silver Schmidt hammer, was 62.6, which corresponds to a uniaxial compressive strength of ~105 MPa. The Vp-velocity, measured with a low-frequency ultrasonic flaw detector at load steps of 50%, 60%, 70%, and 80%, typically decreases in the order of X-axis < Y-axis < Z-axis with increasing load steps. This oder contrasts with that of the initial Vp-velocities. As the load step increases the factors that reduce the Vp-velocity in the X-axis direction are more influential than those in the Y-axis or Z-axis directions. This indicates that the initial state of rocks can vary and is dependent on the stress state.