METHOD AND APPARATUS FOR FORMING A REINFORCED CONCRETE PILE IN AN EARTH SITUS

Abstract: The invention relates to a method and apparatus for forming a reinforced concrete pile in an earth situs by means of a hollow-shafted auger which is screwed into the earth situs and after having reached the required depth is withdrawn without rotation whilst concrete is fed into the bored hole through the hollow shaft of the auger during said withdrawal said auger (3, 4) being provided with openings (11) or indents (10) through which rods, such as reinforcing rods or pipes (7) extend parallel to the axis of the auger such that in case pipes (7) are used rein­ forcing rods (9) are placed into said pipes (7) before the withdrawal of the auger and left in the hole during with­ drawal of the auger and left in the hole during with­ drawal of the auger (3, 4) whilst the case of rods extending through indents (10) or openings (11) said rods are left in the hole during the withdrawal of the auger when said rods are reinforcing rods or reinforcing rods are substituted for the said rods before the said withdrawal and left in the hole during withdrawal.

Description: Method and apparatus for forming a reinforced concrete pile in an earth situs This invention relates to a method for forming a reinforced concrete pile in an earth situs, in which a hollow-shafted auger is screwed into an earth situs and as the auger is withdrawn from the hole, concrete is fed into the hole through the hollow core of the auger and reinforcing rods are provided in the concrete. Such a method is generally known; according to this known method an auger with a comparatively large diameter is used, which is driven into the ground like a corkscrew and which, after it has reached the requisite depth, is withdrawn again by rotating same at the same time. As the auger is withdrawn from the hole, concrete or the like is supplied through the hollow core of the auger, so that the borehole is being filled up beneath the withdrawing auger. Often, serious problems-¯are involved whenYa concrete pile of this kind is provided with a reinforcement. It is only after withdrawal of the auger that the reinforcement can be inserted into the concrete still fresh. In doing so, considerable resistance is experienced, so that only comparatively short lengths can be positioned and it is not quite certain in which direction the reinforcing rods will project. It is the object of this invention to provide an improved method and apparatus. In accordance with this invention, said object is achieved in that during drilling an auger is used, the helical blades of said auger being provided with a series of openings or indents in line with each other and that during the drilling operation a bar or pipe projects through each series of openings or indents, whereby during the non-rotatably withdrawal of the auger and the introduction of the concrete t,nt rods, which hal been provided in the path of the bars, i.e. through the pile before the withdrawal of the auger, will remain behind in the hole. This means that during the drilling operation an auger is used, the blades of which being coupled to each other in longitudinal direction of the auger by bars or pipes which have to cooperate with the rotating auger and which, therefore, have to move with respect to the earth entering between the auger blades. Surprisingly, it was found that this happens and that the auger is properly being filled with earth, whereby only the earth which is substantially outside the rods or pipes but within the circumference of the auger is slighty stirred. When the auger has thus been installed at its proper depth the bars could be replaced by the reinforcing rods desired. This could be considered when there is a risk that during the drilling operation a comparatively thin reinforcing rod might bend. Therefore, during drilling, thick bars will be used, which are withdrawn when drilling has been completed and which are then replaced by the reinforcing rods. Naturally, the bars are preferably the reinforcing rods, which remain in the hole when the auger is being withdrawn. When through-pipes are used, the reinforcing rods are passed therethrough before the auger is withdrawn. It is thus achieved that the concrete supplied through the hollow core surrounds the rods already positioned in the hole. Bor the first time, it is thus possible to install reinforcing rods the full length, i.e. height of the pile. The invention will now be elucidated more in detail with reference to the accompanying drawing, wherein: Fig. 1 illustrates one embodiment of the method with an apparatus in accordance with the invention; and Fig. 2 illustrates a variant. In Fig. 1, a diagrammatic representation of part of a framework is indicated by reference numeral 1 and the G ar case 2 of the auger is movable in vertical direction along said framework. The auger 3 comprises hollow core 4 and communicates with a hose 5 through casing 2; concrete is fed through said hose. The hollow core is surrounded by helical blades 6 which, preferably, constitute a continuous helical line. Pipes 7 and 8 pass through a series of openings running parallel to the centre line of the auger and a reinforcing rod 9 may be inserted into said pipes. When the borehole has its requisite depth, as shown in Fig. 1, rods 9 are positioned within pipes 7 and 8 and in other pipes, if required, whereupon the auger is nonrotatably withdrawn while leaving the rods behind in the hole; simultaneously, said hole is being filled by feeding concrete into the bottom of the hole through hose 5 and hollow core 4. Instead of pipes, it is also possible to provide the helical blades with indents 10 or openings 11. During the drilling operation there are bars in said openings or in dents azd., preferably, they are reinforcing rods which remain behind in the hole when the auger is withdrawn. At their lower ends, the pipes may be closed, e.g. by a plug, said plug being removed by the rods. It is now possible to install clean rods, e.e. which are not fouled by earth, and thus the adhesion between rods and concrete will be improved. It is also possible to carry out sounding tests through the pipes in order to check the assumed bearing capacity of the floor of the borehole.

Claims: f r CLAIMS 1. Method for forming a reinforced concrete pile in an earth situs, in which a hollow-shafted auger is screwed into an earth situ and as the auger is withdrawn from the hole, concrete is fed into the hole through the hollow core of the auger, and reinforcing rods are provided in the concrete, characterized in that during drilling an auger is used, the helical blades (3) of said auger being provided with a series of openings (11) or indents (10) incline with each other and that during the drilling operation a bar or pipe (7) projects through each series of openings or indents, whereby during the non-rotatably withdrawal of the auger and the introduction of the concrete the rods (9), which had been provided in the path of the bars, i.e. through the pipes (7) before the withdrawal of the auger, will remain behind in the hole. 2. Method according to claim 1, characterized in that the bars consist of reinforcing rods. 3. Auger for applying the method according to claim 1 or 2, characterized in that the blades are provided with aligned openings (11) or indents (10). 4. Auger according to claim 3, characterized in that pipes (7) are secured in aligned openings or indents provided in the blades, said pipes running parallel to the centre line of the auger.

Inventors: BRONS, KAREL FREDERIK
Applicants: HOLLANDSCHE BETON GROEP N.V.
Application year: 1979
Main classification: E02D5
IPC codes: E02D5