Table 2. Comparison 



summary of stone overlay 



stability. 



Comparison 



Tank 



No. of tests 



Avg. N| 



Results 



Boulders, 











100-pct coverage 

 to 



small 



4 



1.72 



A 10-pct reduction in 

 NJ for 67-pct overlay. 



67-pct coverage 



small 



2 



1.55 





Boulders and quarrystone. 











100-pct boulders 



to 

 100-pct quarrystone 



small 

 small 



4 

 2 



1.72 

 1.70 



Boulders and quarrystone 

 100-pct overlays have 

 equal stability. 



Quarrystone, 











100-pct quarrystone 



to 

 100-pct quarrystone 



large 



2 



2.38 



Small-scale N| must be 

 increased by 40 pet to 



small 



2 



1.70 



correspond to prototype 

 tests results. 



Table 3. Comparison of stone gradations. 



Comparison 



^'^max 



^min 



Ahrens, 1975 



This study (prototype tests) 



4W50 

 3.IW50 



O.125W50 

 O.4W50 



18 



