After having used the above relationships, (20), and (21) in development 

 of the forces required for penetration, questions have arisen regardinq 

 the appropriateness of the magnitudes used for many of the terms. As 

 will be shown later, it is not appropriate to spend a great deal of OTEC 

 effort in resolving uncertainties regarding embedment of cutting edqes 

 in sand, at least at this stage of the effort. Later presentations will 

 show that the most efficient deadweiaht desiqn on sand will use only very 

 shallow cutting edges. 



3. Results, Force Required to Embed. Steel cuttinq edqes were 

 given the greater attention because they are only one-half the thickness 

 of concrete cutting edges and thus reauire significantly less force to 

 embed. The forces required for embedment, O e , were calculated for various 

 sizes of square blocks (widths = B) and for Z/B ratios of 0.1, 0.2, 0.3, 

 and 0.4 on cohesive soils and 0.05, 0.10, 0.15, and 0.20 on non-cohesive 

 soils. Intermediate cutting edges were placed beneath the anchor blocks 

 to ensure develoDment of a planar failure Diane beneath the anchor. The 

 ratio of cutting edge spacing to length, b/Z, varied with the soil type: 

 ratios of b/Z = 2, 3, 5, and 6 were used in Soil Cateaories A, R, C, and 

 D resDectively. The bearing areas and wall areas of all cutting edqes 

 were summed to yield the A and A areas respectively. 



Figures 46, 47, 48, and 49 present the forces reauired to embed 

 cutting edges in Soil Cateqories A, B, C, and D resDectively. The forces 

 for embedment are represented as solid lines. The dashed curve on these 

 Dlots will be exolained in the subseauent seciton. 



Optimum Cutting Edge Ratios. 



1. Approach . After the development of data above showina the 

 submerged weiqhts necessary to embed cutting edges for deadweiqht anchors 

 for varying B, Z/B, b/Z, and soil strength profiles, it was then of interest 

 to look for optimum cuttinq edqe characteristics. First, optimum cuttina 

 edqe characteristics were defined as those that would provide the reauired 

 lateral load capacity for the minimum reauired embedment load, e . Given _ 

 this definition, it was then necessary to develop a curve of loci of cuttinq 

 edqe characteristics capable of resistina the reauired lateral load, i.e., 

 18 MN or 180 Mn (4xl0 6 lbs or 40x10° lbs) depending on the environment. The 

 curve of loci is a function of Z/B and B and is represented as a dashed line 

 on Fiqures 46 - 49. 



The method for develooina this curve of loci was to first enter 

 Figures 38, 39, and 40 (and one other unpublished curve for category B soil) 

 and pick out B and Z/B parameters capable of resistinq the reauired loadina. 

 With these values for the respective soil category, Fiaures 46 throuqh 49 

 were entered from the B axis until the anpronriate Z/B curve was encountered 

 Thus the loci of cutting edge characteristics capable of resisting the 

 lateral loadina were defined. . 



2 Results Figure 46 indicates for .a cateqory A soil there is not 

 much difference in performance for different anchor-block/cuttmg-edqe 

 associations. Please note this evaluation does not touch on the subject 

 of overturninq potential which becomes worse with increased Z/B ratio. 



92 



