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|Title:||High-explosives cratering in frozen and unfrozen soils in Alaska|
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||CRREL report ; 80-9.|
Abstract: Explosive cratering tests were conducted in seasonally frozen and thawed gravel at Fort Richardson near Anchorage, Alaska, and in seasonally frozen and thawed silt overlying permafrost and in silt permafrost at Fort Wainwright near Fairbanks, Alaska. Explosive charge weights ranged from 26 to 3120 lb and charge burial depths ranged from about 3 to 40 ft. The cube root of the charge weight scaling was used to determine maximum scaled crater dimensions and optimum scaled depth of burial of the charge. Test results for frozen and thawed gravel were essenlially the same because of the low moisture content and the relatively shallow depth of freezing (5 to 6 ft). The optimum depth of burial of the charge for maximizing the apparent radius and depth and the true radius was about 1.8 times the cube root of the charge weight for both the frozen and thawed conditions. In seasonally frozen silt overlying a talik and silt permafrost the maximum scaled crater dimensions and optimum scaled burial depths of the charge were smaller than for the thawed condition except for the true crater dimensions. The channeling of energy in the talik produces maximum crater dimensions and an optimum burial depth for the true crater that is larger than for the thawed condition. The results for the homogeneous silt permafrost were very similar to the frozen gravel results with much smaller maximum crater dimensions and smaller optimum charge burial depths than for the thawed silt overlying permafrost. The required charge weight to produce a crater with a given apparent depth is nearly three times greater for silt permafrost than for thawed silt and nearly two times greater for a given apparent crater radius. Mobility tests were conducted with an armored personnel carrier (M·113) in the craters in thawed silt. Two types of craters were effective barriers to normal vehicle travel. One type had a larger diameter than the other and had a fallback mound because of a deeper burial depth. The other had a smaller diameter but had very steep side slopes with the crater blown clear of ejecta.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||CRREL Report|