Induced Soil Liquefaction for the Freeing of Grounded Ships
Aggour, Mohamed S.
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The objective of this study is to determine the feasibility of freeing a grounded ship by liquefying the surrounding soils. Ships either moored or traveling in near-shore waters and subjected to storm events, will experience waves energetic enough to direct the ship toward the shore. The ship can then become embedded in the soils (grounded) close to the shore. The study included two phases. Phase one was an experimental study where models of three ship sections representing standard classes of ships were constructed. These models were embedded in a saturated sand in an especially constructed tank. Pull tests were done initially to establish benchmark freeing forces and then air blasts were used to produce the dynamic force needed to liquefy the surrounding soils. The models subsequently regained buoyancy. The second phase of the study utilized the data obtained from the testing program to extrapolate those data to a response of an actual-size ship. The conclusion showed that ships grounded can be freed by liquefaction of the surrounding soils. This novel technique of restoring a ship’s buoyancy and thus refloating it was demonstrated experimentally on model ships and analytically by determining the air pressure needed to free an actual ship in a grounding event. This new technique will have an economical value for the shipping industry and could provide an environmentally safe approach in dealing with grounded ships.