Table 6. Summary of maximum runup for different conditions, 



Table 



Wave condition 



Maximum R 



O) 



3 



Constant period; T = 7.0 seconds 



7.05 





4 



Constant period; T = 13.0 seconds 



12.45 





5 



Constant steepness: 

 H^/gT 2 = 0.0104; 

 T max = 7 -° seconds 



6.75 





************************************ 



2. Rubble Slopes . 



Runup data for rubble slopes have traditionally been separated 

 according to structure type, whether for rubble-mound structures or for 

 riprap revetments. There is no essential difference between the two 

 types of structures with respect to stone sizes. "Riprap" is commonly 

 used for rubble protection of an embankment slope that is high relative 

 to expected waves. "Rubble mound" is usually applied to structures 

 such as breakwaters and jetties in which the top of a relatively imper- 

 meable core is at or near the SWL, and the part of the structure above 

 the core is relatively permeable. The rubble-mound structure would be 

 expected to absorb and transmit an appreciable amount of energy through 

 the upper, permeable part of the structure. 



Of the numerous tests conducted on rubble slopes, most have been 

 principally studies of armor unit stability rather than wave runup. 

 Most tests where runup data were obtained have been for rather limited 

 wave conditions or structure geometry, and usually model specific con- 

 ditions for a prototype installation. 



Available runup data for rubble slopes may be divided between studies 

 with quarrystone and studies with concrete armor units. Quarrystone 

 dimensions used in this study are the median sieve size for small-scale 

 laboratory tests (if" given) , or the calculated diameter of a sphere of 

 weight equal to the median quarrystone weight; i.e., the nominal diam- 

 eter. No evaluation of grading (or sorting) of the armor stone sizes 

 is attempted. However, most quarrystone layers would be well sorted 

 (poorly graded) but the degree of sorting is only a relative term-- 

 relative to another assortment of stones. A poorly sorted (well-graded) 

 armor layer would have a large fraction of smaller rocks which could fit 

 in the void spaces between larger stones and, therefore, reduce the cover 

 layer permeability and roughness. 



Concrete armor units are represented by a characteristic length dis- 

 cussed later in this section. 



a. Quarrystone Armor Units . Most of the available rubble-slope 

 data apply to quarrystone armor units. Other types of armor units 



60 



