Decompression system for offshore gravity structure - controlling pore water pressures in permeable foundation and actuated by sea swell

摘要

The decompression system is for use on offshore gravity structures, e.g. exploiting maritime oilfields, it is esp. for use on permeable foundations e.g. of sandy soil, and prevents the build-up of excessive pore-water pressures. Pressure differentials created by the sea-swell are used to control the system. The structure has cellular storage chambers above the foundation and superimposed by a hollow vertical column. A network of drain-pipes communicates with the sea at a level somewhat below that of the lowest wave-trough, and is controlled by a slave -valve. The valve opens when the sea pressure differ from a datum pressure by a specified valve, thus, maintaining foundation pressures below normal hydrostatic pressures. The drainage system inc decompression tubes which are installed beneath the foundation slab. A collector pipe leads from decompression tubes to the sea outlet.