Explosive Embedment Anchors 



History . Some means other than or in addition to free-fall impetus 

 is essential to embed anchors deep enough to gain greater holding 

 capabilities than can be expected of free-fall anchors. Accordingly, 

 the program to develop a better deep sea anchoring capability has 

 included investigation of anchors with power features to achieve 

 embedment. One such type is referred to as explosive anchors. 



Explosive anchors utilize a propellant charge to impart high 

 velocity to the anchor which by virtue of its kinetic energy then 

 penetrates into the seafloor. Initial development work on explosive 

 anchors began about 1959. Two private industrial concerns provided the 

 initiative to conduct the early work. Shortly thereafter, the U. S. 

 Army Mobility Equipment Research and Development Center (MERDC) formerly 

 U. S. Army Engineering Research and Development Laboratory (ERDL) at 

 Fort Belvoir, Virginia sponsored the development of one of the two 

 concepts to meet requirements for special offshore mooring capability 

 for anchors in amphibious operations. The Naval Civil Engineering 

 Laboratory (NCEL) provided support facilities for some of the early 

 testing sponsored by MERDC. 



The investigation of explosive anchors for deep ocean application 

 was undertaken at NCEL in 1965. At that time, two commercial anchors 

 emanating from the efforts of the two private concerns were being 

 marketed as off-the-shelf items. Also, work on the anchor design 

 MERDC was sponsoring under contract had been taken in-house and an 

 anchor similar to one of the commercial items had been achieved. NCEL's 

 investigation with explosive anchors has included tests of the two 

 commercial anchors followed by tests of the MERDC anchor. Results of 

 tests of the commercial anchors were reported by Smith (1966b) . 

 Development work on explosive anchors of MERDC was reported by Christians 

 (1967). Pertinent facts about the commercial and MERDC anchors are 

 described here to place the explosive anchor developments in perspective 

 relative to the total ongoing deep ocean anchoring program. 



Description . The explosive anchor designs tested at the Laboratory 

 are shown in Figures 7, 8, and 9. Though they differ in shape and/or 

 size, each is comprised of two major components; an anchor-projectile 

 and a gun-reactor. The anchor-projectile is that portion of the 

 assembly that is propelled into the seafloor. One style of anchor- 

 projectile is a shield shape that penetrates the seafloor edgewise, 

 then "keys" over to a position that presents a maximum area to resist 

 pullout when load is applied. This style is evident in Figures 8 and 

 9. The second style of anchor-projectile consists of a shank that 

 contains two flukes. This anchor-projectile enters the seafloor 

 endwise. When loads are applied, the flukes extend outward to acquire 

 increased resistance to extraction. This style of anchor-projectile 

 is shown in Figure 7. Both styles of anchor-projectile have a separate 

 portion called a piston that inserts into the gun- reactor and is expelled 

 when the propellant is ignited. 



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