Patent GB-1084022-A (GB)
Title: Improvements relating to underwater anchorages
IPC: B63B21/50
Filed: 1965-02-22
Abstract: 1,084,022. Anchoring buoyant bodies. W. KOHRING. Feb. 22, 1966 [Feb. 22, 1965; Feb. 26, 1965], Nos. 7487/65 and 8423/65. Heading B7S. [Also in Division E1] An anchoring device or anchorage for, e.g., an underwater oil-storage tank, comprises a pointed tubular body 1A and a mooring block 4A connected thereto by a plurality of flexible strips or reeds 1, each of which strips has a rectangular profile in crosssection, so that it is capable of flexing only in a direction normal to its breadth, and is twisted to render it helical whereby said direction varies from one end of the strip to the other. The body 1A is driven into subaqueous ground by a pile-driving method, a rigid tube 13A being temporarily placed in abutment with a ring 6A, which is fixed to said body, to facilitate this procedure. The ends of the strips are secured to the peripheries of plates 7A, 9A attached to the body 1A and the block 4A, respectively, most of the plates being of circular shape, Fig. 8 (not shown), and of differing diameters, the smallest plate being square. A flexible oil-filled sleeve 10A is attached to the block 4A to provide protection for the strips. The block 4A may be rendered buoyant so as to keep the strips in a vertical attitude. The plates 7A, 9A may be replaced by parallel bars (14), Fig. 9 (not shown). Each strip may be fabricated from a plurality of short strips connected together by intermediate blocks, adjacent plates being angularly displaced relative to one another to from a helix. Each strip, or each of the short strips therein, may be constituted by a plurality of strands or laminµ. When the anchoring device is to be lodged in soft ground, it may engage with a tapered tube (16), Fig. 10 (not shown), which is attached to hollow rings (15, 22) by radial plates (17), said rings being supported by oblique tubes (24) engaged by piles (25). Each of the piles (25) carries a helical strip (29), Fig. 11 (not shown), and a head (30), which abuts the top of the associated tube (24). Further tubes (23) connect the interiors of the rings to each other and apertures (27) are provided in the tubes (24) in register with the rings, whereby concrete can be injected through a tube (26) in the lower ring (22) to add weight to the structure and lock the piles relative to the tubes (24). A plurality of such structures (36), Fig. 13 (not shown), may be used to anchor an underwater oil-storage tank (34), a pair of cables or hawsers (35) being fixed to each structure and a rotatable ring (37), Fig. 15 (not shown), on the tank. The ring comprises a plurality of box-section segments with gaps therebetween filled by wedge-shaped rubber blocks (44), Fig. 14 (not shown), which are bonded to the segments and tubes (45), said tubes being fixed by pins (49), Fig. 16 (not shown), engaging with radial supports (46) secured to the tank. The ring (37) is supported by bearing pads (40) and the blocks (44) permit limited movement of each segment relative to the pins (49). A plurality of strips or reeds 1 may be used to anchor the buoyant roof (52), Figs. 17 and 18 (not shown), of an underwater oil-storage tank to a concrete base or caisson (54). The roof has a skirt portion (53), which overlaps perforated walls (51) fixed to the base. The lower ends of the strips are secured to radial walls (56) on the base, the latter being either placed directly in contact with subaqueous ground (60), Fig. 19 (not shown), or attached to such ground (65) by anchoring devices (67) of the kind shown, Fig. 7. Alternatively, the base has a plurality of rectilinear walls (63), Fig. 20 (not shown), which intersect one another at right-angles, the strips (3) being attached to the point of intersection. The strips may be enclosed in oil-filled sleeves.