GB2356647A

GB2356647A - Capping a pile wall

Info

Publication number: GB2356647A
Application number: GB9927947A
Authority: GB
Inventors: Iain Barr; Cliff Scott
Original assignee: Cementation Foundations Skanska Ltd; Kvaerner Cementation Foundations Ltd
Current assignee: Cementation Skanska Ltd
Priority date: 1999-11-27
Filing date: 1999-11-27
Publication date: 2001-05-30
Anticipated expiration: 2019-11-27
Also published as: EP1103663A1; ATE350539T1; DE60032717D1; GB2356647B; GB9927947D0; EP1103663B1

Abstract

A precast capping beam element comprises a parallel pair of concrete retaining panels connected together by reinforcing rods cast into both panels and projecting into the space therebetween. One panel may be larger than the other. A method is also disclosed for forming a capping beam of a pile wall by placing the capping beam element over a line of piles so that the reinforcing rods of the piles project into the space, and filling the space with concrete. <IMAGE>

Description

2356647 Pile Wall Capping The present invention relates to the formation

of capping beams for pile walls.

A pile can either be a pre-formed shaft which is hammered into the ground or formed by drilling a hole in the ground and pumping concrete into the hole. The latter technique may involve using an auger with a hollow shaft, and pumping concrete through the shaft to form the pile as auger is being withdrawn. Reinforcing rods are usually introduced into the concrete before it sets, with their top ends left projecting from the top of the concrete.

A pile wall consists of a row of piles, which may be either spaced apart or packed closely together (even to the point of intersecting each other in what is termed a secant wall). With a secant wall, the piles are necessarily all parallel, and are normally vertical. With nonintersecting piles, some (or even all) may be raked (sloping).

A pile wall is frequently completed by forming a horizontal capping beam along its top edge. The capping beam is normally formed by levelling the tops of the piles (and any ground in between them), placing shuttering to define the sides of the beam, and pouring concrete to form the beam.

Reinforcing rods will normally be introduced into the concrete of the beam.

The poured concrete will also surround the reinforcing rods projecting from the top ends of the piles, so firmly linking the piles with the beam.

The general object of the present invention is to provide an improved way of forming a capping beam of a pile wall.

2 According to one aspect there is provided a method of forming a pile wall comprising forming a line of piles with projecting reinforcing rods, placing thereover a capping beam element comprising a parallel pair of concrete retaining panels connected together and each having transverse reinforcing rods projecting therefrom towards the other panel, and pouring concrete into the space between the two panels. Preferably one panel has a larger cross-section than the other, and the smaller panel is preferably slightly shorter than the larger. The panels are preferably tongued and grooved at their ends. The panels may have lifting eyes or the like formed in their upper edges. One or both panels may also have fixing holed for a railing formed in their upper edges.

According to another aspect there is provided a pre-cast capping beam element comprising a pair of panels as just defined and connected together by transverse reinforcing rods each cast into both panels.

By means of the invention the need for fabrication of form-work on-site is avoided. This results in decreasing costs, particularly the on-site labour costs, and a quicker installation as well as an increase in quality of the resulting capping beam.

The present panels will normally be manufactured in a factory, which allows considerably better control of quality than operations on site, and gives an improved finish to the sides of the capping beam. The amount of operations on site is substantially reduced, so that the time, labour, and expense on site is reduced, and adverse weather conditions have reduced effect.

Further features of the invention will become apparent from the following description of a pile wall capping beam element and a method of

3 forming a pile wall both in accordance with the invention, given by way of example and with reference to the drawings, in which:

Fig. I is a diagrammatic perspective view of the capping beam element; Figs. 2 to 6 show successive stages in forming a pile wall using the capping beam element; and Figs. 7 to 13 show successive stages in forming a pile wall using a modified beam panel.

Referring to Fig. 1, the capping beam element consists of two concrete retaining panels 10 and I I linked to each other by transverse reinforcing rods 12. Panel 10 is generally higher and thicker than panel 11, and is intended for the outer side of the pile wall, as described later. Panel 10 has a short projecting tongue 16 at one end and a groove or recess 15 at the other end, so that a series of capping beam elements placed end to end will engage with each other and so avoid misalignment. Panel I I is similarly tongued and grooved at its ends.

The connected panels 10 and I I are formed in a steel mould with a core which is withdrawn once the concrete has reached its initial set. The core shutters have slots to allow the reinforcing rods to pass through them.

It is sometimes desirable or necessary for a pile wall to be slightly c-urved. Such curvature is normally convex towards the outside of the wall.

Panel I I is therefore made very slightly shorter than panel 12, so that when a series of panel elements are fully engaged, they form a slight curve rather than a straight line. The size of the tongues and grooves is sufficient to ensure interlocking of both panels even with a straight line, but the slight length 4 difference permits a greater curvature to be achieved before full interlocking of the outer panels 10 is lost.

The panels 10 and I I contain internal reinforcing rods (not shown), and the rods 12 are in the form of rectangular loops in the vertical plane, as indicated at the near end of the panels. Further reinforcing rods 13 are attached to the rods 12 in the space between the panels and parallel to the panels.

The panels 10 and I I have eyes 17 set in them as shown to allow the capping beam element to be lifted. Panel 10 also has a series of pairs of railing fixing holes 18 formed in it.

Figs. 2 to 6 show end views of various stages in the formation of a pile wall and its capping beam. Fig. 2 shows the ground 25 with vertical piles 26 and raked piles 27. The piles may typically be of around 275 mm diameter, with a spacing of I m, alternately vertical and raked. As shown, the piles 26 and 27 have reinforcing rods 28 and 29 respectively projecting from them. The area is then leveled as shown in Fig. 3, with the ground 25 being leveled and the tops of the piles being broken down if necessary. The reinforcing rods 29 of the raked piles 27 are bent to the vertical and their ends are bent over as shown.

The capping beam element is then placed over the tops of the piles, as shown in Fig. 4, with the larger panel 10 on the outside of the pile wall, and with the tops of the piles approximately centrally located between the panels 10 and 11. Concrete 30 is then poured into the region between the two panels, as shown in Fig. 5.

Fig. 5 also shows further details of the reinforcing rods of the capping beam element. The loops 12 of rods connecting the two panels together are shown; also shown are longitudinal reinforcing rods 19 and 20 in the panels 10 and I I respectively and vertical rod loops 21 in panel 10.

The wall is finally finished by back-filling the region behind it with earth 31 to the level of the outer panel 10, re-grading the earth in front of the wall as shown at 32, and attaching a handrail 33, as shown in Fig. 6.

The technique described above is suitable for piles which have reinforcing rods which can be bent manually, i.e. rods with diameters up to about 16 mm. With such rods, the capping beam can be placed over the projecting reinforcing rods and the positions of the rods can readily be adjusted if they clash with the rods connecting the two panels of the capping beam.

If the pile reinforcing rods are of substantially larger diameter, then the technique is preferably modified to the one shown in figs. 7 to 13. The parts corresponding to those in the above embodiment are shown by the same identifying, number followed by a prime ('). Instead of a capping beam consisting of two panels interconnected by reinforcing rods 12, two separate panels are used. Panel I V is formed, as shown in Fig. 7, with rods 12' projecting from the inner face; panel 10' is similar. The rods 12' are of a length slightly less than the intended distance between the panels, so that when the panels are placed in position, their projecting rods overlap. Each panel also has dovetail grooves 35, so that the spacing between the panels can be set by connecting them, e.g. by halfen connecting rods. In fig. 10 the rake pile reinforcing bar 29' is terminated in an end plate 36 rather than being bent over as in the previous embodiment.

Claims

1 A method of forming a pile wall comprising forming a line of piles with projecting reinforcing rods, placing thereover a capping beam element comprising a substantially parallel pair of concrete retaining panels connected together and each having transverse reinforcing rods projecting therefrom towards the other panel, and pouring concrete or grout into the space between the two panels.

2 A method according to claim I wherein one panel has a larger crosssection than the other.

3 A method according to claim 2 wherein the smaller panel is slightly shorter than the larger.

4 A method according to any previous claim wherein the panels are tongued and grooved at their ends.

A method according. to any previous claim wherein the panels have lifting eyes or the like formed in their upper edges.

6 A method according to any previous claim wherein at least one panel has fixing holes for a railing formed in its upper edge.

7 A method of forming a pile wall substantially as herein described with reference to Figs. 2 to 6.

7

8 A pre-cast capping beam element comprising a pair of panels as defined in any previous claim and connected together by transverse reinforcing rods each cast into both panels.

9 A pre-cast capping beam element substantially as herein described with reference to Fig. 1.

Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International 10 Convention (Paris Convention).