Vibration of Piled Rocks—Which Rock Can Be Removed?

To identify rocks which can be taken from rock-mound without disturbing stability of other rocks, vibration characteristics of rocks in mound were investigated by measuring vibration of each rock in an artificial mound. A mound of sand stone rocks of randomly-shaped, length 30–40 cm was constructed on the ground and was subjected by artificial vibration. The vibration of rock on the top (“free rock”) and that of a rock supporting the top rock (“supporting rock”) were measured. Their characteristics showed that the dominant frequency was different; 40–50 Hz for the free rock and 50–60 Hz for the supporting rock. After changing the free rock to a supporting rock by means of leaning another rock on it, the dominant frequency became to 50 and 60 Hz. It is considered that waves of frequency range of 40–50 were amplified in the free rock in test conditions of this paper. According to these findings, the authors discussed about possibility of identify free rocks from supporting rocks by vibration characteristics.