Experimental Investigations on the Response of Bedload Sediment to Vibration

Abstract

Research results on sediment vibration characteristics are scarce, and knowledge on the effect of the particle size on the sediment vibration response is still limited. In this study, natural pebbles of different heights—A, B and C—were selected (hA < hB < hC). Miniature acceleration sensors were installed inside the pebble. Experimental methods were used to measure the vibration process of pebbles on the rough bed surface and to measure the near-bed velocities simultaneously. The test results show that the sequence of pebble vibration and entrainment is A-C-B as the flow rate increases. The vibration intensity of pebbles A and B tended to increase before approaching the entrainment threshold but weakened when approaching the entrainment threshold; the vibration frequency, on the contrary, first decreased and then increased. The vibration intensity of pebble C decreased first and then increased, and when approaching the entrainment threshold, it rolled directly. The vibration frequency first increased and then decreased, and near the entrainment threshold, there was no vibration. Thus, it was demonstrated that with the increase in pebble height, the average vibration intensity increases, and the average vibration frequency decreases. The results of this research provide a reference for exploring the dynamic mechanism of the bed load in mountain rivers.