| 摘要 |
PURPOSE:To support stably the substructure of an offshore working platform on the bottom of a dock without burdening partial load on the dock bottom by providing a load dispersion layer between the substructure and the dock bottom in the construction of the offshore working platform for oil-well drilling. CONSTITUTION:A wall 7 is provided on the dock bottom 5, and a load dispersion layer 6 consisting of a granular substance (e.g., sugar) is provided in the area surrounded by the wall 7. The total weight of a landing and elevating type offshore working platform is transmitted to a substructure 3 provided at the lower ends of struts 2, and the force acting on the lower slope 3a of the substructure 3 is dispersed into a wider area than a projected area A1 from the layer 6 to the dock bottom 5 of the substructure 3. Even when a projection 3b is provided at the lower center of the substructure 3, no stress is concentrated on the substructure 3 because the layer 6 naturally follows the shape of the projection 3b. Unit struts 2a and 2b are built up on the substructure 3, and then the working platform 1 is lifted by operating a drive mechanism 4. Then, another unit strut 2b' is lifted up by a crane 8 and joined with the upper end of the unit strut 2b. Thus, a given length of the strut 2 is built up. |
