Effect of material particle size on the permeability characteristics and sediment retention performance of cascade permeable dam

Abstract

The permeable dam is a dam constructed with gravel or other material to control the sediment in rivers or channels. Experiments were conducted to study the effects of the flow rate, sediment concentration, and dam material size D on the sediment retention and permeability characteristics of the cascade permeable dams. The results show that when the water level H1t before the first dam reaches the specified failure height, the total water volume for D = 1–2 mm is inversely proportional to the sediment concentration and basically increases as the flow rate increases. The sediment mass retained by the first dam accounts for 44–56% (D = 1–2 mm) and 26–35% (D = 3–5 mm) of the total sediment mass retained by the cascade dams, and the former mainly realizes the sediment retention through the retention of the first dam, while the latter through the material retention and sediment deposition between two adjacent dams. The average permeability coefficient k of the first dam was observed to decrease by 39–62% (D = 3–5 mm) and 46–64 (D = 1–2 mm) due to the sediment clogging. The decrease rate of k (D = 1–2 mm) or decrease amplitude of k (D = 3–5 mm) are positively correlated with the sediment concentration. Under all working conditions, H1t rises rapidly and then steadily, and the rising rate for D = 1–2 mm is proportional to the sediment concentration, and increases first and then decreases as the flow rate increases. The prediction formula of H1t is proposed based on the experimental data. The research results are of reference value for the design and study of permeable dams in the future.