that practical deadweight anchors for OTEC in most deep ocean environments 

 win not tail ina bearing capacity mode. However, deadweight anchors on 

 non-cohesive sediments (sands) are susceptible to bearing capacity failure, 

 inis section will delve into the reasons for this low bearing capacity on 

 sand, will indicate the magnitude of the capacity reductions, and will 

 delineate steps necessary to make the anchors adequate. 



Analysis. The vertical load capacity of a very large, shallow, 

 horizontal bearing surface is calculated using the following relationships; 



Q = B'L'(0.5y B'N s d i k + Y Z(N - 1) s d i k + (23) 



Y Y Y Y Y ' v q ' q q q q v ; 



sN s d i k ) 

 c c c c c' 



where B'= B - 2e, 



e^ eccentricity of the load resultant parallel to the 

 B dimension (B is the short dimension) 



L'= L - 2e 2 



e 2 = eccentricity of the load resultant parallel to the 

 L dimension (L is the long dimension) 



s , s , s = factors tc account for anchor plane shape 



M Y c 



d , d , d = factors to account for the shearing resistance of soil 

 4 above the bearing plane of the anchor 



factors to account for inclination of 



k , k , k = factors to account for compressibility of the supporting 

 q Y c soil 



These factors are all dis'cussed and relationships for evaluating them are 

 presented in CEL TM 42-76-1 (Valent et al . , 1976). The values assigned to 

 these factors for the bearing capacity analysis of square deadweight anchors 

 are presented in Table 17. 



Some uncertainty surrounds the selection of the inclination and the 

 compressibility factors. Both sets of factors deserve further experimental 

 verification. The inclination factors i and i are developed from the 

 expressions presented in TM 42-76-1 for a non-cohesive soil as a function 

 °f Ph^v (Figure 50). The authors note that the expressions developed are 

 simplified and may not be totally valid for values of P^/R.,, approaching 1 .0. 



i , i , i = factors to account for inclination of the resistant load 



99 



