Stability of armour layer over sand bed in waves/currents: A case study

Stability and suction removal of the sand bed under the rock-armoring layer were exposed under the wave and discharge generated steady flow and coexisting flow investigated at apron area of the open channel discharge system. Determination of the stability of the armoring layer was achieved bymicro and macro scale tests focused just sample stone(s) and all armoring area in 1/25 scale laboratory physical model. In micro scale tests, small underwater camera was recorded the motion of the stones and flow properties measured at the same location by Acoustic Doppler (ADV) just over the stones at critical points. Shields parameter and Shields initiation of the motion criteria were applied of the measurements results. The variation range of the Shields parameter were determined (?) as; 0.003-0.007 for steady current case (only discharge condition), 0.008-0.04 for wave only (no discharge) and 0.01-0.03 in coexisting flow case. Photogrammetric method was applied at macro scale tests by 3D photographs of the armoring area before and at the end of the experiments. Instability was not determined for whole armoring layer by photogrammetric approach.