| 摘要 |
Method of and apparatus for forming (casting) closed-ended hollow tanks of preferably circular or modified circular section and of diameter and height (length) ranging from small up to one hundred feet in diameter, a thousand feet in length and weighing one hundred million pounds, such as are suitable for under polar-ice transport and thereafter storage of petroleum, and for other uses as well. Forming and casting of such tanks is achieved preferably by slip-forming walls of concrete tanks (although conventional concrete forming and casting procedures and apparatus may also be employed), in ocean-depth water in which the tank is progressively submerged as forming and casting proceeds. The apparatus for carrying out the aforesaid method comprises a floating barge assembly comprising two spaced-apart trussed-together barges and a submersible casting barge disposed in the space between said spaced-apart barges on which latter a slab of desired configuration providing the closed bottom end of the tank is first cast. Towers of substantial height are provided on the mutually facing edges of said spaced-apart barges, atop each of which are mounted sheaves over which steel cables are trained, by which the casting barge and the tank as it is progressively formed and cast are suspended in such manner that both casting barge and the progressively formed and cast tank are free to swing with a pendulum action, it being explained however that the suspending cables support but a small yet sufficient amount of the total weight involved to maintain the pendulum action. The bulk of the weight of the concrete tank is supported first by the buoyancy of the casting barge and later by the buoyancy of the tank itself as it is progressively cast and lowered into the water. As forming of the tank proceeds, the steel cables are alternately released and reset to lower the tank and casting barge into the water while maintaining the upper end of the tank at a relatively constant elevation above water level, as by admitting water or other suitable ballast to the tank interior in amount counteracting the buoyancy of the tank upon the latter becoming greater than its weight and that of the casting barge, etc. . . Upon the tank being formed and cast to a particular length (depth), the submerged casting barge may be floated away from same, such without in any way interfering with further forming and casting of the tank should such be desired. |
