This condition could be expected in most seafloor areas; however, in many 

 category D and some category C environments scour could be a problem. 

 Deadweight anchor design should seek to minimize the ootential for scour 

 bv streamlinina the deadweight and by providing scour protection about 

 the anchor DeriDhery. 



In order to minimize the potential for overturning, initial consid- 

 erations of lateral load capacity assumed a ratio of cutting edqe lenqth, 

 Z, to deadweiaht width, B, of 0.1. Later evaluation of the lateral load 

 developed as a f unci ton of the anchor deadweight reauired to embed the 

 skirts showed the ratio of Z/B of 0.1 to also be very desirable from the 

 standpoint of design efficiency. 



Analysis of Passive Wedge Comnonent. 



1. Cohesive Soil . The analysis of the passive wedqe component 

 for a cohesive soil (categories A, B, and C) utilized the relationship 



R ] = 1/2 Y Z 2 + 2sZ (12) 



where R = lateral load resistance per unit width of passive wedge (N/m) 

 P 



y = buoyand unit weioht of soil (N/m ) 



Z = length of cutting edge (m) 



s = undrained shear strength of soil (Pa) 



Values of undrained shear strength of the seafloor sediment, s, and of 

 the buoyant unit weight of the sediment, y, used in the analysis are as 

 presented in Fiaure 1 and Table 1. The total lateral resistance arising 

 from the passive wedae is found by multiplying the lateral load resistance 

 per unit width, Rp 1 , by the width of the passive wedge. For the square 

 plan deadweight anchors treated herein, the width of the passive wedge 

 would be the block width, B. The passive wedqe component of the lateral 

 load resistance is then: 



R = R ] B (13) 



p p 



This value of the passive wedge lateral load resistance is believed real- 

 izable at all moorina line directions, i.e., the same value can be realized 

 even when the moorinq line is actinq alonq a diagonal of the souare dead- 

 weiaht anchor block." When evaluating the lateral load capacity of circular 

 plan deadweight anchors, it would appear reasonable to reduce the average 

 passive pressure acting on a diameter as is done when evaluating the 

 lateral load capacity of cylindrical piles (Czerniak, 1957). Lateral load 

 capacities derived from the passive wedge are presented as a function of 

 anchor side dimension for Soil Cateaories A and C in Fiqures 34 and 35 

 respectively. 



70 



