The Q values shown in Figure 51 and elsewhere in this report were 

 calculated assuming that the skirts penetrate evenly and vertically. A 

 canted or inclined deadweight would produce uneven penetration and would 

 result in higher embedment force. Thus, development of means to ensure 

 uniform penetration of the large plan area deadweights required of OTEC 

 may be necessary if uneven penetration is in fact a problem. 



The R c curve represents the submerged weight of a block of prestressed 

 concrete of dimensions B by B square and 0.1B high, the dimensions assumed 

 for the OTEC deadweight anchors. The potential submerged weight, R c , 

 of a block of these dimensions is 200 percent greater than the weight 

 required to embed the cutting edges, Q e . Thus, considerable "excess" 

 vertical load carrying potential is available should a non-zero mooring 

 line angle be necessary or should additional weight be required to account 

 for uneven penetration. 



On a category C soil (cohesive and strong) the relationship of 

 bearing capacity to the loads being applied is much the same, that is, 

 the applied vertical loads will be considerably lower than the soil bearing 

 capacity (Figure 52). However, the relationship of the loads Rl, Q ?s and 

 R c shifts somewhat. The required submerged weight on the seafloor is 

 again given by Equation 24. As before, the assumed volume of the anchor 

 block, B by B by 0.1B high, provides ample space for weighting material 

 with density equivalent to prestressed concrete. 



2. Non-Cohesive . On non-cohesive sediments, Category D soil, the 

 lateral load capacity is influenced much more drastically by load inclina- 

 tion as compared to the inclined load capacity of cohesive soils. Figure 

 50 shows that for a load inclination of 0.79 rad (45 deg), the inclination 

 factors i Y and i q in the bearing capacity equation, (23), are equal to 

 zero. Since the undrained shear strength, s, is also zero for non-cohesive 

 soils, the bearing capacity is exceeded. Figure 50 illustrates that the 

 vertical load component, R v , must be increased for any given lateral load, 

 PH, in order to increase the magnitudes of the inclination factors i Y and 

 iq' Figure 53 describes the interdependence of R v > the applied vertical 

 load, and Q, the resulting realizable bearing capacity. As the applied 

 load R v is increased, the bearing capacity, Q, is increased, but at a much 

 greater rate. At some point the applied load and the bearing capacity 

 will balance each other. For the case in question, balance occurs at a 

 load component ratio, P H /Ry, of 0.65 corresponding to an applied vertical 

 load, R Y , of 280 HN (62x10b lbs) for an applied lateral load, Ph, of 

 180 MN (40x106 lbs). „ ., , . 



The authors note that a bearing capacity type failure on sand may not 

 be a serious problem. As discussed in the first report, the major result of 

 a bearing capacity type failure is line abrasion on the high side of the 

 block as the load direction shifts. In a uni-directional loading environ- 

 ment (Gulf Stream) this line abrasion should not occur. Model testing to 

 be carried out in the next phase of the OTEC effort should c arify the ser- 

 iousness of a bearing capacity type failure. The extremely large weights 

 Indicated by the analysis above may in fact be unnecessary if a bearing 

 capacity type failure is found to be of minor consequence. 



104 



