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김영화,장보안,김재동,이찬구,문병관,Kim, Yeong Hwa,Jang, Bo-An,Kim, Jae Dong,Rhee, Chan Goo,Moon, Byeung Kwan 대한자원환경지질학회 1997 자원환경지질 Vol.30 No.3
The behavior of rocks and microcrack development due to fatigue stresses are investigated using cyclic loading tests and ultrasonic velocity measurements. Twenty six medium-grained granite samples from the Pochon area are selected for measurements. Ultrasonic velocities are measured for samples before fatigue test to characterize the pre-existing microcracks. Then, thirteen different cycles of loadings with 70% and 80% dynamic strength are applied to the samples. The ultrasonic velocities are measured again to compare velocities after applications of fatigue stress with those before applications of fatigue stress. The results show that most microcracks are developed along the direction parallel to the axis of loading and that the amount of microcracks increases, as loading levels and numbers of cycle increase.