INTRODUCTION 



Purpose 



Tnis second progress report presents performance characteristics 

 of possible anchors for the Ocean Thermal -Energy Conversion power plant 

 (OTEC). The first report (Valent et al, 1976) gave a general descrip- 

 tion of possible OTEC anchor concepts. 



Procedure 



Each anchor type presented in the first OTEC anchor report was 

 evaluated using available data and standard analysis techniques. All 

 calculations were made assuming that load was statically applied. The 

 advantages and limitations of combining several anchors of the same 

 type to achieve desired capacity were discussed. 



Anchor holding capacities for OTEC were calculated for the soil 

 categories described in the first report. A summary of these soil 

 categories and assumed anchor loading is given in the next section. 



ENVIRONMENT 

 Site Categories 



The sediment strength profiles described in the first report were 

 grouped into three site categories. One shear strength profile was 

 developed to represent each category (Figure 1). These three site 

 categories, plus two additional categories for sands and for outcropping 

 and near-surface seafloor rock respectively, were used as representa- 

 tive OTEC seafloor environments. The selection, sizing, and comparing 

 of anchor types and combinations refers back to these baseline categories. 



Table 1 is a summary listing of site category characteristics. Note 

 that eacn category has been assigned a descriptive word title in Table 1; 

 for example, the sediments of site category A can be descriptively 

 referred to as clays and clayey silts. 



For site category D, sands, a predominantly quartz grain material 

 is assumed having^a friction angle of 0.52 rad (30 deg) and a submerged unit 

 weight of 6.8kN/m (43 pcf). Such material under repeated loading may be 

 susceptible to liquefaction. If the median grain size (DV Q ) is found to 

 lie between 0.02 and 0.2 mm, then the mooring system shouia be designed 

 to reduce the effects of repeated loading or high factors of safety 

 (greater than 10) should be used. 



The material characteristics of site category E, that for exposed 

 or shallowly buried rock, are not resolved at this point. The quantified 



