WO1990011412A1

WO1990011412A1 - A procedure for the forming of consolidation and foundation piles with embedded reinforcements

Info

Publication number: WO1990011412A1
Application number: PCT/IT1989/000020
Authority: WO
Inventors: Dino Canepari; Cesare Melegari
Original assignee: Iniectojet S.P.A.
Priority date: 1989-03-22
Filing date: 1989-03-22
Publication date: 1990-10-04
Also published as: EP0417111A1

Abstract

The art field is that of casting consolidation and foundation piles in-situ using ultra-high pressure liquid concrete injection casting methods; in the procedure disclosed, a metal reinforcement (7) is positioned prior to effecting the cast.

Description

A procedure for the forming of consolidation and foundation piles with embedded reinforcements

The invention relates to a procedure for in-situ casting of consolidation and foundation piles with embedded reinforcements. The prior art embraces methods of consolidating the soil that consist essentially in preparing a liquid mix of concrete and binders and injecting it into the ground at ultra-high pressure.

The mix is injected by sinking a rod into the earth to the envisaged consolidation depth. Such a rod is provided with a special boring head, and with a injection valve carrying one or more nozzles disposed at right angles to the rod axis, substantially within the same transverse plane. The rod is mounted to a device by which it is rotated and traversed along its own axis.

Ultra-high pressure injection of the mix occurs as the rod is withdrawn, rotating about its axis. The conventional method thus outlined is beset by certain drawbacks in given applications such as those, for example, where a reinforcement has to be embedded axially in the concrete. This is achieved, conventionally, by casting the consolidation pile and then positioning tubular or other reinforcing members in a separate operation: such a procedure involves a considerable waste of time, and cannot ensure coaxial alignment between the reinforcement and the cast; the reinforcement can in fact become deflected uncontrollably during the positioning step, occasioning a subsequent loss of performance in terms of strength specifications. In a procedure set forth by the same applicant, use is made of a pipe, perforated with a plurality of uniformly distributed radial holes extending down to the envisaged consolidation depth. The pipe is planted in the ground, and the liquid concrete mix injected at high pressure, in such a way that the pipe remains embedded in a column of concrete and soil created by the turbulence- of the injection. The in-situ casting of consolidation piles with embedded reinforcements is simplified considerably by adoption of such a system; on the other hand, the pipe is costly, by reason of the need for a uniform perforation, and cannot be recovered. Accordingly, the object of the invention is to set forth a procedure that will permit of positioning any given reinforcement of tubular or cage type embodiment in a consolidation pile cast in-situ using high pressure injection techniques, ensuring coaxial alignment between the reinforcement and the cast, and of accomplishing such operations swiftly and inexpensively.

The stated object is achieved by adoption of a procedure as characterized in the appended claims. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: figs 1...4 illustrate four steps of the casting procedure disclosed; figs 5 and 6 are sectional illustrations of the consolidation pile showing two different types of reinforcement; figs 7 and 8 are sectional illustrations of the consolidation pile showing two different types of pipe, seen during the withdrawal step. With reference to fig 1 of the drawings, the first step of the procedure is that of sinking a bore in the ground 1 down to a prescribed consolidation depth 2, using conventional mechanical equipment 3 by means of which a pipe 5 is driven straight into the soil, traversing along its own axis. 6 denotes a rotatable rod inserted into the pipe 5, the end of which carries a drill head. With the spoil removed and the pipe 5 firmly in position, the rod 6 is withdrawn (fig 2) , and the pipe left

05 in place.

The side wall of the pipe 5 is perforated to enable the passage of liquid concrete from inside to ^' outside, as will occur in a subsequent step of the procedure. _lυ The third step of the procedure (fig 3) consists in positioning a reinforcement 7 in the bore; such a reinforcement might be tubular, as illustrated in fig 5, or composed of single bars or wires arranged to coincide with the generators of an imaginary

*L5 cylinder (fig 6) .

The final step of the procedure is one of pumping liquid concrete into the bore at high pressure and withdrawing the perforated pipe 5 at one and the same time, thereby consolidating the soil around a

20 pile 9 in which the reinforcement 7 remains firmly embedded.

Fig 7 illustrates a pipe 5a affording an annular cavity, whereas the pipe 5b illustrated in fig 8 affords a set of channels arranged to coincide with

25 generators of the pipe. It will be clear that the procedure as described above admits of embedding any type of reinforcement in a cast-in-situ pile, in contrast to conventional procedures, which permit of embedding bars or wires only, and to relatively shallow depths.

The reinforcement might be embodied as a cage, or tubular, or as a rod, or indeed as a simple pole, without any difficulty as regards its embedding in and alignment with the cast. Casting pressure may vary between 300 and 800 bar, according to requirements, without affecting the position of the reinforcement inside the pipe 5. The cavity of a pipe 5 as in fig 7 can be used to pump in back-fill material or to pump out spoil: materials pumped in could be concrete, mortar or any filling considered suitable for the purpose; in the case of materials pumped out, control will be provided over any excess pressure occasioned by the high injection pressure and disposal of the spoil.

Claims

1) A procedure for the forming of consolidation and foundation piles with embedded reinforcements, characterized in that it comprises the steps of:

- simultaneously sinking a pilot bore in the ground to a prescribed consolidation depth by means of conventional implements, and driving an ultra-high pressure liquid concrete injection pipe (5) down the bore to the same depth;

- withdrawing the implements used to sink the bore, and leaving the pipe (5) driven into the ground;

- positioning a reinforcement (7) internally of the pipe (5) , down to a prescribed, depth;

- simultaneously injecting a liquid concrete mix through the pipe (5) into the bore at ultra-high pressure, and withdrawing the pipe from the ground.

2) A procedure as in claim 1, wherein the final step of injecting liquid concrete mix is effected at ultra-high pressure of between 200 and 800 bar. 3) A procedure as in claim 1, wherein the internally positioned reinforcement (7) is of tubular type embodiment.

4) A procedure as in claim 1, wherein the internally positioned reinforcement (7) is of sectional type embodiment.

5) A procedure as in claim 1, wherein the internally positioned reinforcement (7) is of mesh type embodiment.

6) A procedure as in claim 1, wherein the internally positioned reinforcement (7) is of lattice type embodiment.

7) A procedure as in claim 1, wherein the internally positioned reinforcement (7) is of cage type embodiment.