Purpose and Approach 



4. The purpose of this study was to develop suitable design guidance 

 for the sizing of toe berm and toe buttressing stone using experimental 

 results from laboratory physical models. A series of two-dimensional (2-D) 

 and three-dimensional (3-D) stability tests was developed and conducted in 

 physical models to address the sizing of toe berm and toe buttressing stone in 

 breaking wave environments. The 2-D tests focussed on toe stone sizing on 

 rubble-mound structure trunks exposed to 90-deg wave attack, i.e., wave 

 orthogonals perpendicular to structure crest. Toe berm armor stone sizing for 

 oblique wave attack on rubble -mound structure heads and trunks was examined in 

 the 3-D model tests. Guidance for sizing toe berm armor stone was developed 

 for a range of wave and swl conditions. Guidance for sizing of toe buttress- 

 ing stone was developed for a limited set of incident wave conditions on 

 structure trunks. 



