GB712674A - Improvements in prestressed concrete piles - Google Patents

Abstract

712,674. Concrete piles. STENT PRECAST CONCRETE, Ltd. Sept. 24, 1953 [Sept. 25, 1952], No. 24041/52. Class 68(2) A pre-stressed one-piece concrete pile is formed by threading one end of a high tensile steel wire cable c through a thin-walled metal tube b and distending the other end to form a cage-like structure d round a metal loop e, concrete then being cast around the cage d, the tube b, and other reinforcements including four longitudinal steel bars k surrounded by mild steel links l, m, and steel rod mats n close to the end of the pile. A sleeve i is also placed around the lower end of the tube band the neck of the cage d, hooks j being bent round the tube b for carrying purposes. A pointed cast iron shoe may be fitted to the toe of the pile. After the concrete has set and the cage d is anchored in the toe of the pile, the cable c is tensioned, e.g. by a hydraulic jack, and is held in tension by a wedge, or clamp f, the ends of the cable c<SP>1</SP> being cut and spread within a recess at the head of the pile. Grouting is then injected into the tube b until it emerges from an outlet g in the toe of the pile. In an alternative arrangement a tubular passage is formed by casting concrete round a collapsible rubber hose which is withdrawn when the concrete has set, the cable being threaded through the tubular passage, and further concrete being cast round the cage d and on the main portion of the pile. Should the pile be driven short the projecting portion of the head can be broken away and the bars k can be bent at right angles to link with a pile of a superstructure cast thereon; alternatively, should the pile require to be driven further, the bars k can be exposed and more bars can be spliced thereto, the head of the pile being extended by casting more concrete. In a modification the links m are at wider intervals, the concrete being further reinforced by a helically bent mild steel rod surrounding the tube c.