2. Non-Cohesive Soil . The analysis of the passive wedge component 

 for a non-cohesive soil (category D, sand) utilized the relationship 



Rp 1 = 1/2 y l\ (14) 



where K = coefficient of passive lateral earth pressure on the 

 cutting edge 



Table 14 Dresents values for the coefficient of passive lateral earth 

 pressure on the wall of the leading cutting edge, along with a list of 

 assumptions inherent in the use of these K values. The sand of 

 cateaory D was assumed to have an angle o? internal friction, <f> of 

 0.52 rad (30 deg), a conservative value. From Table 14 the K value for 

 a (J) = 0.52 rad soil is 4.78. Conservatism has been interjected in the 

 selection of <J> = 0.52 rad because of the unknown cutting edge Derformance 

 in hiahly calcareous cateaory D soils. The values of the effective 

 friction angle of a calcareous soil on a cutting edge wall, 6, may be 

 considerably reduced due to the soft nature of the carbonate grains 

 relative to steel. -.The buoyant unit weight of the sediment, y, was 

 assumed as 5.5 kN/m (35 pcf ) . The conservative value was used for two 

 reasons: (1) soil in the oassive wedge will be less dense- than soil under 

 the anchor, and (2) soil in the passive wedge might be removed by scour. 

 Lateral load capacities derived from the passive wedge are presented in 

 Fiaure 36. 



Analysis of Base Shear Component . 



1. Cohesive Soil. The deadweight anchor is assumed to slide on 

 a soil failure plane passing through the tips of the cuttina edge as 

 shown in Figure 33. The resistance to lateral load developed alona this 

 plane in a cohesive soil is in its simplest form: 



R b = s x A ' (15) 



o 

 where A = bearing area of the deadweight (m ). 



Lateral load resistances calculated using (15) may prove somewhat uncon- 

 servative in some more-sensitive seafloor sediments because the failure 

 zone will probably develop in a proaressive fashion with the realizable, 

 averaae shear strength on the base shearing plane being somewhat lower 

 than the measurable undrained shear strength of the sediment, s. No 

 allowance for the progressive failure effect has been made in this pre- 

 liminary effort. Undrained shear strengths used in the anlysis were 

 obtained from the strength profiles of Figure 1 at soil depths eoual to 

 the cutting edge length. 



Lateral load capacities arisinq from base shear in category A and 

 C soils have been plotted as a function of anchor width in Figures 34 and 

 35 respectively. Note that in these figures the ratio of cuttinq edae 

 lenath to anchor width, Z/B, has been fixed at 0.1. 



73 



