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http://dx.doi.org/10.9720/kseg.2017.1.51

Evaluation of the State of Rocks in Load Steps by Low-frequency Ultrasonic Flaw Detection  

Kang, Seong-Seung (Department of Energy and Resources Engineering, Chosun University)
Kim, Jongheuck (Department of Energy and Resources Engineering, Chosun University)
Noh, Jeongdu (The Research Institute of Advanced Engineering Technology, Chosun University)
Na, Tae-Yoo (The Research Institute of Advanced Engineering Technology, Chosun University)
Jang, Hyongdoo (Western Australian School of Mines, Curtin University)
Ko, Chin-Surk (Department of Energy and Resources Engineering, Chosun University)
Publication Information
The Journal of Engineering Geology / v.27, no.1, 2017 , pp. 51-58 More about this Journal
Abstract
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.
Keywords
Low-frequency ultrasonic flaw detection; CND; Silver Schmidt hammer; Vp-velocity; Load step;
Citations & Related Records
Times Cited By KSCI : 3  (Citation Analysis)
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