PART IV: SEAWALL GEOMETRY 

 Precast Wall Technology 



18. Prior to model studies, precast seawall technology was reviewed to 

 determine if any particular device complying with such a construction method- 

 ology could be employed in the Virginia Beach seawall design. A literature 

 review, along with establishment of several industry contacts with companies 

 involved in constructing precast coastal structures and discussions with sev- 

 eral researchers in other nations, was conducted. A few patented precast de- 

 vices (such as stresswall by Stresswall International and Neptune Caisson by 

 Mitsubishi Corp.) were identified as possibly applicable and pursued through 

 more detailed discussions. Reinforced Earth, a recent seawall installation at 

 Pacifica, California, was inspected. However, none of the patented devices 

 could be both constructed in the stepped-wall configuration required for 

 Virginia Beach and demonstrated to be stable in a high wave energy coastal 

 environment . 



19. Although it could be feasible to develop a precast unit or plan 

 which could be used to construct the Virginia Beach seawall components off 

 site, such a plan would need careful structural and hydrodynamic assessment 

 better conducted as an independent detailed structural design. The scope of 

 this task and time constraints associated with the overall study did not allow 

 for development of the specific structural component. The proposed seawall 

 configuration was therefore not adjusted to incorporate any existing precast 

 system. Development of a precast system tailored for use at Virginia Beach 

 may be a subject for consideration during later phases of the design or as a 

 value engineering activity. 



Physical Model Tests 



20. The physical model tests were run in two phases. Phase I was an 

 initial effort consisting of observations of the seawall and wave response and 

 the stability of the stone toe in addition to wave gage data and overtopping 

 measurements. Phase II of the model tests incorporated changes to the seawall 

 design based on the Phase I results. A summary of the model tests is provided 

 below. Heimbaugh et al. (1988) contains a detailed report on these tests. 



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