bearing surface. For the most part, on the predominantly soft 

 cohesive seafloor sediments, typical values are 0.1 to 0.2. 



One purpose of deadweight anchor design is to increase the lateral 

 holding capacity by providing roughened surfaces or teeth to better 

 engage the seafloor surface. Cutting edqes, often referred to as skirts 

 in the case of cutting edges around the perimeter of a deadweiaht, are 

 a common solution (Figure 32). When the cutting edges have been embedded 

 vertically in the seafloor, lateral sliding of the deadweiaht occurs on 

 shearing zones (possibly Dlanes) emanating from the tip of the cutting 

 edges. Thus the cutting edges serve to force the shear zone into a 

 typically stronger soil. In addition, for the deadweight to move hori- 

 zontally, the wedge of soil in front of the leading skirt must be pushed 

 up and out of the way providing another component of lateral load resistance. 



Vertical Load Resistance. Increasinq the moorinq line angle at the 

 anchor from zero causes a vertical component of load to be applied to 

 the anchor. This vertical load component must be resisted by a portion 

 of the submerged weight of the deadweight anchor. (Figure 33). 



Overturning Resistance . The deadweight anchor must have sufficient 

 resistance to overturning arising from its shape, distribution of mass, 

 and location of mooring line attachment to remain stable under any load- 

 inq condition. The deadweight must be very flat or sauat, that is, it 

 must have a large width, B.'as compared to its heiqht, H. The center of 

 mass must be located as low as possible. Lastly, the mooring line attach- 

 ment point on the deadweight must be positioned as low on the anchor as 

 oossible so as to minimize the lever arm of the horizontal load component, 

 P To minimize overturning potential, much of this study assumes the 

 deadweight anchor height to be one-tenth of the width or 



H =0.1B 



11 



The cutting edge length Z, also influences the overturning potential. 

 Deadweights with low ratios of cutting edge penetration to anchor width, 

 i e , Z/B, will have a lesser potential for overturning. 



Deadweight anchors reouired to resist equal loads from any direction 

 offer little flexibility in varying the point of mooring line attachment. 

 The attachment point must be centrally located allowing only movement to 

 a point lower on the anchor profile. However, deadweight anchors which 

 must resist their heavier loadings from one general direction offer 

 potential for optimizing the attachment point location. Rather than 

 elaborate here, the reader is referred to the Pearl Harbor concrete anchor 

 illustrated in Figure 10(d) of CEL TM-42-76-1 (Valent et al . , 1976). This 

 report is limited to consideration of centrally loaded, souare-plan 

 deadweight anchors. 



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