Trends in Phreatic Surface Motion in Rubble‐Mound Breakwaters

Experimental studies were undertaken to investigate phreatic surface motion in rubble-mound breakwater models. This motion was assessed as a function of a number of governing variables, including armor unit type, geometry of the armor layer, breakwater slope, and core permeability. Tests were conducted in a two-dimensional wave flume using regular waves. Both the maximum and average phreatic surface elevations were found to increase with increasing wave height, increasing wave period, and steeper slopes. The setup within the core was also significantly higher for tests with spheres in the armor layer, due to the increased permeability normal to the slope. Increasing core permeability resulted in sharp rises in the maximum and average phreatic surface elevations.