An experimental study and its consideration on the depressions of granular layers under vibrating load : comparison with verical and horizontal vibrations

We have been making a study of vibrating depressions of granular layers (sand and gravel) under vibrating loads. In this paper we measured permanent surface depressions and internal accelerations when the vertical or horizontal vibrations acted on the granular layers, and studied the comparison with both vibrations on the basis of some theoretical conceptions. We obtained several conclusions as follows : (1) In both vibrations conditions of vibrating depressions were almost similar, and in the first term of vibration both compressive and flowing depressions were recognized, after the time passing compressive depressions were completed and only flowing depressions were reserved. (2) Compared with both vibrations, depressiors by the horizontal were more remarkable in low frequency (800～1300rpm) and on the other hand depressions by the vertical were more remarkable in high frequecy (1800～2300rpm). (3) The tendency above described is clearly recognezed by comparing characteristic constants A, B and tanα on the vibrating depressions we proposed here.