GB282820A - Improvements relating to caissons - Google Patents

Abstract

282,820. Rotinoff, A. G. Dec. 29, 1926, [Convention date]. Sinking caissons by jetting.-Caissons are sunk by excavating the soil inside the bottom of the caisson by compressed air jets and blowing out the excavated material through the caisson. The air supply pipes may have quick-acting valves whereby the air acts intermittently and explosively instead of continuously. Water jets and cutting means may assist the air jets, and additional upwardly-directed air jets may assist the removal. The jetting apparatus is removable. In Fig. 1, a caisson 1 with a cutting shoe 3 removably supports a platform 6 carrying a discharge tube 7 flared at its lower end where it is welded &c. to a sleeve 8; air supply tubes 10, with curved lower ends, are held to the tube 7 bv brackets 29 and blocks 29<1>, or by rings, and connected to an annular supply pipe 19 while water supply pipes 11 extend through the tubes 10 and annular pipe 19 to supply pipes 20. In use, the tubes 10 are rotated as desired by a crank 18, gear 15, internally toothed sleeve 14 and gears 12, An inflatable tube 8<1> is provided between the sleeve 8 and the caisson, and is connected by a tube 22 to the pipe 19, whereby the tube 8 is inflated during operations to provide a seal. Pipes 27 also lead from the pipe 19 and their upwardlyturned lower ends extend through the wall of the discharge tube 7 to supply air to assist in removing spoil. Cutters 44 assist in breaking up the material and are so placed as to form openings into which the pipes 10 may direct air &c. In a modification, the water supply pipes are also connected to an annular supply pipe and the lower ends of the supply pipes are outwardllyturned and arranged to give a whirling motion to the fluid; while in a further modification the fluid supply pipes pass through vertical grooves on the exterior of the caisson, their lower ends being detachably connected to nozzles. In Figs. 10 and 11, steel caissons are employed, the sinking being assisted by steam hammers 91. In Fig. 10, the discharge pipe 93 is supported by a frame 94 and its foot is surrounded by a casing 98 containing annular air and water supply pipes 99, 103, respectively, the space between the casing and caisson being sealed by an inflatable tube 110; in Fig. 11, two discharge pipes 114, 115, terminate below in helical ducts 117, 118, surrounding a casing 119 within which a cylinder 124 is rotatably arranged, the cylinder being connected to the air supply pipe 121 and carrying delivery nozzles 126 arranged so that the air tends to rotate the cylinder 124, water being supplied through an axial pipe 123. In ground such as quicksands, the lower part of the caisson may be enlarged as in Fig. 17 to extend the supporting surface; such caisson may have a stream-line inner surface 134, water being supplied through an axial pipe 143 and air through a pipe 141 with a stream-line end 142, the pipe 141 also having upwardly-turned nozzles 145, 146, delivering air to assist in removing spoil. The air pressure may be such as to force soil from below to fill the space round the upper part 130 of the caisson, or such space may be filled by spoil discharged above. Large caissons may be divided below by transverse partitions into separate chambers each provided with its own excavating apparatus; several such caissons may be sunk adjacent each other to form a wall, guiding means being provided on the caissons while semi-circular grooves in the meeting faces are afterwards filled with concrete to give a tight joint.