GB870497A - Methods and apparatus for making concrete pile shells and piles - Google Patents

Abstract

870,497. Piles. RAYMOND INTERNATIONAL Inc. Nov. 16, 1959, No. 38690/59. Class 68(2). A method of constructing a hollow concrete pile shell comprises seating a casing 23 on a driving shoe 22, driving it partly into the ground and then positioning therein a hollow mandrel 25 which has centring lugs 26. A hopper 28 is fastened to the top of the casing and concrete is fed into the annulus 27. The complete unit is then driven to its final depth and the casing 23 pulled up. The initial heavy pull may be applied by an apparatus as shown in Fig. 2a or 2b so that a corresponding reactive force will act on the shoe 22 via the mandrel 25. Fig. 2a shows a mast 200 which has a T-head 201 from which are suspended pulley blocks 206 and 207. The cables 204 and 205 are taken to winding drums (not shown). The reaction of the upward force applied to the casing is transferred to the mandrel 25 by a shoulder 203 on the mast. Fig. 2b shows an hydraulic piston 211 and cylinder 212 wherein the piston is attached to a crosshead 214 which is secured by links to the casing, and the cylinder 212 is positioned within the mandrel 25 and has a shoulder 215 which bears on the top of the mandrel. In order to cause the concrete to fill the void left as the casing is withdrawn a vibrator may be provided inside the mandrel, or vibrators may be attached to the casing and drawn up through the concrete with the casing. Setting of the concrete may be hastened by heating the interior of the mandrel by steam, and a water pipe may be provided to subsequently cool the mandrel and assist extraction. In a modification a thin metal liner 40 (not shown, see Fig. 6) is positioned either immediately inside or outside the casing and remains in the ground when the casing is withdrawn. In a second modification a thin corrugated metal liner 87 (Fig. 14), which makes a watertight joint with the driving shoe, is positioned so as to closely surround the mandrel, and remains inside the pile shell when the mandrel is withdrawn. In a third modification the method is used to construct a composite pile comprising lower metal sections 82 and 83 (Fig. 14) and an upper part 81 constructed as described above. In this case the driving shoe is replaced by a driving ring 86 and a conventional taper mandrel 84 is used. So that this mandrel may be withdrawn before the concrete has set, the thin liner 87 is supported against ground pressures until the concrete sets by an auxiliary stiffener shell 91 which is subsequently withdrawn. In a fourth modification a composite pile is formed in which the lower section comprises a parallel tubular element 108, closed by a plate 110 and attached to a driving shoe 107. The assembly is stiffened during driving by a mandrel 103 which partly enters the lower section. When the mandrel has been removed the pile is completed by filling the upper and lower sections with concrete.