6. The model seawall was constructed to reproduce the geometric shape 

 of the prototype structure. Allowances were made for modifications in the 

 geometric shape of the seawall face to accommodate proposed alternatives, 

 i.e., vertical and recurved seawalls. The midsection of the seawall was 

 equipped with features allowing installation of transducers for measuring wave 

 pressures. Aluminum was chosen for construction of this 1-ft-wide section due 

 to its availability, workability, and thermal conductivity. 



Test Facilities and Equipment 



7. A concrete wave flume 5 ft wide, 4 ft deep, and 119 ft long was used 

 for all tests. The flume is equipped with a vertical displacement wave gener- 

 ator capable of producing monochromatic waves of various periods and heights. 

 Test waves of the required characteristics were generated by varying the fre- 

 quency and amplitude of the plunger motion. Test sections were installed in 

 the flume approximately 89 ft from the wave generator. As shown in Figure 2, 

 postulated local prototype bathymetry seaward of the test sections was rep- 

 resented by a compound slope of 1V:22H and 1V:60H for simulated prototype 

 distances of 110 and 1,200 ft (4.4 and 48.0 ft in the model), respectively. 



8. Wave pressures were measured using miniature semiconductor pressure 

 transducers, each equipped with a silicon diaphragm and a 4-arm strain gage 

 bridge. Pressure measurements were calibrated and recorded using a micro- 

 computer. Data were stored on 8-in. floppy discs. Wave pressures were also 

 recorded by an oscillograph capable of accurately recording the high-frequency 

 pressure variations. Simultaneous pressure measurements were made at up to 12 

 different locations along the face of the seawall. Figures 3-5 show these 

 locations for each seawall alternative. 



Test Procedures 



Calibration of the test facility 



9. At the US Army Engineer Waterways Experiment Station (WES), calibra- 

 tion of the wave facility is normally performed without the test section in 

 place; therefore, conditions are analogous to the prototype conditions for 

 which the measured and/or hindcasted wave data were determined. Electrical- 

 resistance type wave gages were positioned in the flume at a point that would 



