Experimental Investigation of Local Scour Around Artificial Reefs in Steady Currents

Artificial reef is a man-made object that is deployed purposefully on the seafloor to restore the offshore fishery resources and the ecological environment. To secure its ecological effects, it is important to study the possible instability of artificial reefs, like drifting and reversing caused by burial and scour in different seafloor conditions. In the present study, experiments of local scour around an artificial reef are carried out in steady currents. The effect of the open-area ratios and the open-hole heights of the cubic reefs, and the bottom angles of the triangular reefs on the time-scale of the scour process and the equilibrium scour depth are investigated. The results indicate that for the cubic artificial reef, the scour depth decreases with the increasing open-area ratios, and increases with the increasing open-hole heights. In the present study, the optimal prototype of the cubic reef with an open-area ratio of 0.49 and open-height of 0.7m produces the minimum scour depth. For the triangular reef, the scour depth increases when the bottom angle increases. Moreover, based on the experimental results, empirical equations of the effects of the cut-opening and the bottom angle on the maximum equilibrium scour depth are proposed. The formulas will provide theoretical support and practical guidance for the optimized design and construction of artificial reefs.