A Treatise On The Principles And Practice Of Dock Engineering

COMMERCIAL GRAVING DOCK AT BARRY. 50I radiated granite stones to carry the cast steel roller paths, 9 inches wide, for the gates. The outer division is filled by two culverts, 7 feet 4 inches high by 4 feet wide, one of them passing round the caisson chainber. The inner division is filled from the outer division by two similar culverts. A loop culvert, 6 feet by 3 feet 6 inches, is also provided, leading from the main discharge culvert into a sump to increase the rapidity of filling. For emptying the dock, a sump or well, 61 feet long by 12 feet broad by 11 feet deep, is constructed under the engine-house, and the water is discharged therefrom into Princes Dock through a main discharge culvert, 11 feet 6 inches high by 8 feet wide. The pumping installation consists of two 60-inch centrifugal pumps, each driven by a pair of vertical direct- acting engines, with cylinders 28 inches diameter and 24 inches stroke, the steam pressure being 110 Ibs. per square inch. An auxiliary 15-inch pump deals with leakage water. Steam is supplied from four boilers of the return tubular marine type, with assisted draught, each 12 feet 6 inches diameter and 10 feet long, giving a working pressure of 130 Ibs. per square inch. The capacity of the dock when no vessels are in, is about 2,202,000 cubic feet or 13,762,500 gallons at high water. This quantity can be discharged in 1 hour 40 minutes. The equipment consists of a 25-ton steam travelling crane on the north side, with sweep to centre of dock ; five 5-ton direct-acting hydraulic capstans and 12 hand capstans, together with 31 mooring posts. The sets of portable keel-blocks, 620 in nuniber, are laid down in three lines. Their general sizes are 5 feet long, 16 inches broad, and 30 inches high. The Portland cement concrete was of the following proportions : —For the foundation cylinders, 5 to 1 ; for floor and sides of dock, 6 to 1 ; for pockets in brickwork of entrance and end walls, 9 to 1; for moulded granolithic-faced ashlar, 6 to 1 ; and the granolithic facing, 3 to 1. Commercial Graving Dock at Barry.* The genera] dimensions of this dock, completed in 1893, are as follows ^vide figs 503 and 504):— Ft. Ins. Extreme length,................................................. 747 6 Outer compartment................................................384 6 Inner compartment,...............................................363 0 Width of outer entrance at coping level, .... 60 3 Width of inner entrance at coping level, .... 59 41 Depth of water on outer sill at H.W.O.S.T., ... 26 8| Depth of water on inner sill at H.W.O.S.T., ... 27 2J Width of dock chambers at coping.................................113 6 Widtli of dock chambers at floor.................................100 0 The earthwork consisted chiefly of red marl. Magnesian limestone was :also found, and was used in the dry rubble drains behind the walls and for * Robinson on “The Barry Graving Docks,” Min. Proc. Inst. C. E., vol. cxvi.