AN EXPERIMENTAL STUDY ON THE WAVE FORCE ON THE SLOPE OF SMOOTHED MOUND BREAKWATER WITH AND WITHOUT CROWN WALL UNDER MEDIUM-LONG PERIOD WAVES

A Mound breakwater is a common coastal defence against waves. The wave force has greatly related to the stability of the armour blocks. Medium-long period waves have greatly impact on coastal structures and are attracting more and more attention. In this work, the wave force and pressure distribution on the slope of smoothed mound breakwater were studied by experiments. Total of 140 tests were carried out, in which 70 sets are breakwaters with crown wall, and the other 70 sets are breakwaters without crown wall. In the scope of medium-long period waves, the wave force on slope of the breakwater with crown wall is similar to that without crown wall. Neelamani method is more suitable for the breakwater without crown wall and its top submerged. Under short period waves, the maximum pressure on the slope is different. The pressure on the slope with and without crown wall is similar. Pressure at berm with crown wall is greater than that without crown wall. The maximum ratio of the horizontal velocity in front of breakwater with and without crown wall is about 2. A formula was proposed to predict the difference of pressure at the berm with and without crown wall through the difference of reflection coefficient Cr.