Patent GB-770612-A (GB)
Title: Improvements in or relating to piles
IPC: E02D5/36
Filed: 1955-06-27
Abstract: 770,612. Piles. MUELLER, L. June 27, 1955 [July 17, 1954 ; Jan. 8, 1955 ; March 16, 1955], No. 18454/55. Class 68 (2). A pile for a building foundation comprises a hollow steel shaft 1 having a hollow wedgeshaped foot 3 and a projecting shoe 2 secured thereto, the foot 3, comprised either of steel plates welded together as shown, or of a casting of steel, having the upper edges of its inclined sides projecting laterally beyond the width of the shaft 1 to form outlets Q<SP>1</SP>, Q<SP>2</SP>. Holes X are provided in the inclined sides of the shoe, further holes Z<SP>1</SP>, Z<SP>2</SP>, spaced and offset longitudinally, being formed in the shaft 1, and in corresponding distance pieces 4 which are welded at spaced intervals within the shaft. A head 6, welded to the top of the shaft 1, has an opening to receive an inlet pipe 5 for compressed concrete, a packing ring 8 being interposed between the head 6 of the shaft and a head 7 for the pipe 5. A sealing gland 9 is welded around the upper end of the shaft. In operation the steel pile, without the concrete supply pipe 5, is driven into the ground so that the foot 3 compresses the soil around the shaft to form an irregular hollow space, Fig. 1, the last downward stroke of the pile causing the gland 9 to plug the soil in the uppermost section of the hole. The inlet pipe 5 for the compressed concrete is then introduced into the shaft 1, and concrete is forced therein to flow out through the openings Q<SP>1</SP>, Q<SP>2</SP> and X, and into the hollow space surrounding the foot 3. When the lower hollow space has been filled with concrete, the inlet pipe 5 is turned through an angle of 60 degrees so that the lower outlet openings in the pipe 5 coincide with the openings Z<SP>1</SP> in the shaft 1, thus allowing concrete to enter the space around the lower end of the shaft 1. The pipe 5 is subsequently turned through another angle so that concrete can emerge through the openings in the pipe 5, now corresponding with the openings Z<SP>2</SP>, and rise into the space around the shaft, up to the sealing gland 9. With the supply pressure of the concrete now at a low value, the pipe is gradually withdrawn from the pile which is thus slowly filled with concrete. When driving a pile into sticky soil, such as clay, smaller wedge-shaped displacing shoes are also fixed on to the narrow faces of the pile foot 3. Only one inlet pipe 5 is required for a number of piles of identical section. In a modificacation, Fig. 16, the shaft is formed of four steel angle bars 1 interconnected by spacers 24, the upper spacer, having a head ring 6, being made longer than the others to receive a longitudinally adjustable sealing gland, not shown, which is in the form of a collar formed in two halves which are secured together around the shaft 1. The lowermost spacer 24, which extends into the foot 3, has welded therein a thrust member 17 on which can be mounted a hollow ramming shaft 18 which has been inserted into the shaft for driving the pile. To prevent the entry of soil into the internal space of the pile wedge-shaped clearing lugs such as 12 are located over the openings Z<SP>1</SP> and Z<SP>2</SP>, and lugs 19 are arranged over the openings in the foot 3. The foot 3 is also covered at the top by two steel angle members 20 to prevent entry of soil from above. The spacers 24 may be replaced by a single spiral reinforcement. A tensioning device may be fitted to the upper projecting end of the ramming shaft 18 to pre-stress, after the driving operations have been completed, a pile shaft made of light steel round sections. Thin steel wires may also be employed to form the pile shaft. The ramming shaft may be produced from solid section in which case one, or more, concrete supply pipes are connected to it to supply concrete under pressure to the pile foot and the pile shaft.