Appendix A 



SOIL-ANCHOR INTERACTION STUDY TO DETERMINE 



REQUIRED SIZES OF ANCHOR FLUKES 



The deep water anchor was designed by first selecting the fluke (s) 

 that would satisfy the criterion of 20,000 pounds long-term holding 

 capacity In any seafloor. Second, the gun system capable of developing 

 the energy to propel the fluke (s) Into the seafloor was chosen. This 

 appendix outlines the procedures used to optimize fluke design in 

 sediments. The state-of-the-art does not permit this level of analysis 

 for rock. 



The step-by-step approach that was used to determine the required 

 fluke(s) is as follows: 



1. Establish Soil Types . Five soil types cover the realm of 

 anticipated seafloor soils; they are listed in tabular form below. 



Soil Type Soil Properties 



I. Medium density, non-plastic silt y, = 40 pcf; i= 30^ 



II. Medium density silty sand y, = 50 pcf; (() = 35 

 III. Dense sand Y. = 70 pcf; ()) = 40 



IV. Deep water clayey silt y, = 26 pcf; shear strength £,= .3 



effective pressure p 

 V. Carbonate bonded silty clay y, = 30 pcf; c = 300 psf + 1.3p 



2. Develop Curves of Holding Capacity Versus Embedment Depth . 

 Curves of holding capacity versus depth were plotted for each soil 

 type using fluke widths from B = 1 to 5 feet, and ratios of fluke 

 length, L, to fluke width, B, of L/B = 1, 1.5, and 2. Techniques used 

 to develop these curves can be found in Taylor and Lee, 1972. A typical 

 curve at L/B = 1.5 for type IV soil is shown in Figure A-1. Holding 

 capacities below a ratio of depth of embedment to fluke width (D/B) 

 equal to 2 were not calculated. It would not be good construction 

 practice to establish such shallow anchors. 



3. Limit Fluke Sizes and Shapes for Further Analysis . Curves of 

 fluke width versus fluke embedment depth before keying (depth to fluke 

 tip) can be analyzed to eliminate many fluke sizes and shapes from 

 further consideration. Required data were obtained by taking depths 

 for each fluke width from holding capacity-depth curves at a short-term 

 holding capacity of 30 kips, and increasing the depths by values equal 

 to fluke keying distance, assumed equal to 1 3/4 times fluke length, L. 

 The short-term capacity of 30 kips is assumed equivalent to a long-term 

 holding capacity of 20 kips (design requirement) to account for the 

 possible effects of creep or repetitive loading. These curves were 

 separated according to L/B, illustrated in Figure A-2 , and soil type. 



A qualitative evaluation of this type curve enabled a choice of flukes 



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