WO1988009849A1

WO1988009849A1 - Reinforcement for continuously-cast concrete walls

Info

Publication number: WO1988009849A1
Application number: PCT/AU1988/000189
Authority: WO
Inventors: Donald Innes
Original assignee: Foundation Technology Pty. Ltd.
Priority date: 1987-06-12
Filing date: 1988-06-14
Publication date: 1988-12-15
Also published as: EP0393032A4; JPH04500544A; EP0393032A1

Abstract

A reinforcing frame (10) is disclosed for providing continuous reinforcement for a concrete wall (18) cast in longitudinal sections within a trench (17). The frame (10) comprises vertical bars (11) and horizontal bars (12) to form a rectangular cage (14) to one end of which a blocking plate (13) is attached for blocking the flow of wet concrete along the trench (17). The vertical edges of the blocking plate (13) are formed as channel-shaped formations (9) which engage with vertical bars (15) attached to the end of an adjacent further reinforcing frame (16). After the clearances between the formations (9) and the bars (15) have been filled with concrete which has set, continuous longitudinal reinforcement of the concrete wall (18) is achieved. Methods of forming a reinforced concrete wall and producing a multi-tiered concrete retaining wall are also disclosed.

Description

"REINFORCEMENT FOR CONTINUOUSLY-CAST CONCRETE WALLS" -- BACKGROUND OF THE INVENTION --

This invention relates to concrete reinforcement apparatus.

This invention has particular but not exclusive application to the reinforcement of continuously-cast concrete walls, and for illustrative purposes reference will be made to such application. However, it is to be understood that this invention could be used in other applications, such as the reinforcement of walls cast by an intermittent process. Excavations for building sites and tunnels frequently require the forming of retaining walls within the ground before material can be excavated away from one side of the walls to leave a stable excavation. Such walls may also be formed as foundation walls to carry loads down to suitable bearing material, and in this case, no subsequent excavation is carried out. Walls of this type may also be constructed to cut off ground water movement. Such walls have in the past been constructed by boring a line of holes and casting reinforced piles in a closely-spaced row. If this process is used for retaining walls, it is necessary to add substantial horizontal strengthening to the row of piles to maintain their alignment. There is also great difficulty in forming such a wall which is watertight, and thus this process is unsuitable for the production of cut-off walls.

-- DESCRIPTION OF THE PRIOR ART --

Techniques for the continuous excavation of trenches of cross section suitable for retaining walls are available, and a suitable machine is the subject of Australian Patent Application No. PH 6409. While the machine can excavate a trench continuously, reinforcing steel must be placed in the excavation prior to the pouring of concrete, and concrete must be poured around it. Ideally, it is desirable to cast a monolithic wall incorporating continuous reinforcement. However, it is not usually practical to excavate an elongate trench the full length of a desired wall and then install continuous reinforcing steel, as in many soil types, a long open trench will suffer from collapse of parts of the wall. It is thus most desirable that the excavated trench be filled with reinforcing steel and concrete as close as is practicable behind the excavator. Thus, after the trencher has advanced a distance of several metres from its start, an assembly of reinforcing steel known as a "cage" is loweredinto the excavation and conorete is pouted around and through the cage. Since the front of the trench is occupied by the excavating arm on the trencher, blanking means must be provided to prevent concrete clogging the excavating arm.

This procedure results in the formation of a reinforced concrete wall having reinforced segments, and this is unacceptable, as the wall does not provide the necessary strength in bending, shear and tension to perform a retaining function.

-- SUMMARY OF THE PRESENT INVENTION --

The present invention aims to alleviate the above disadvantages and to provide concrete reinforcement means and methods of forming continuous inground reinforced concrete walls which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.

With the foregoing and other objects in view, this invention in one aspect resides broadly in a reinforcing frame for reinforcing a concrete wall cast within a trench, said reinforcing frame including:- reinforcing means for the internal reinforcement of said concrete wall; blocking means co-operable with the opposed side walls of the trench for blocking flow of wet concrete cast about said reinforcing frame at one side of said blocking means; and connector means for connecting said reinforcing frame to an adjacent reinforcing frame.

Preferably, the blocking means comprises a blocking plate of width and height sufficient to substantially block the flow of concrete between the section of trench containing the reinforcing frames and the advancing excavation. Preferably, the blocking plate is attached to one side of the blocking frame, but of course it could be intermediate to thesides of the blocking frame if desired. If the blocking plate is attached to one end of the blocking frame, it is preferred that the connecter means be in the form of slides such as vertical slides formed integrally with the blocking plate and engaging with complementary slides attached to the adjacent end of a second reinforcing frame. In such a case, each reinforcing frame may be a blocking frame.

Preferably, the slides are formed by shaping or fabricating the closure plate to provide one or more guides which may engage slidably with the engagement means on the next reinforcing frame to provide a joint which limits relative movement between the two reinforcing frames in a horizontal plane and which, when the clearances in the joint are filled with a material of high compressive strength such as concrete, locks the two adjacent frames together. If desired, reinforcing frames may incorporate disposable inserts formed of material such as foamed plastics so that voids may be formed in the poured concrete for the location of tension members and blocks associated with anchoring of the panels.

If desired, the blocking plates may be placed intermediate to the opposed sides of respective the reinforcing frames. In such case, the connection between the reinforcing frames may be made by engaging bar-like members or the like through overlapping loops projecting from adjacent reinforcing frames.

The connection means may be constituted by the provision of complementary engagable means which may take the form of a pair of metal plates formed with matching re-entrant profiles and attached to respective opposite sides of the reinforcing frames, which may be in the form of cages.

The edges of the blocking plate which are exposed in the finished wall may be covered with a plastics material or other non-corrosive material to retard corrosion in the blocking plate. Alternatively they may terminate inwardly ofthe trench wall to enable concrete to substantially cover the plates.

In another aspect, this invention resides broadly in a method of forming a reinforced concrete wall including:-

(a) forming a trench by excavating a elongate trench;

(b) providing a reinforcement frame including blocking means and connector means as defined above;

(c) inserting said reinforcing frame into the start of said trench;

(d) placing concrete in and around said reinforcing frame on the side of said blocking means remote from the advancing face of said trench; (e) connecting another said reinforcing frame to said inserted reinforcing frame;

(f) placing concrete in and around said another said reinforcing frame on the side of the blocking means thereon remote from said advancing face of said trench; and (g) repeating the steps (e) and (f) as often as is required to complete said reinforced concrete wall.

Preferably, the elongate trench is excavated by a continuous process such as the use of a trenching machine as described in Australian Patent Application No. PH 6409. Preferably the concrete is placed behind trenching apparatus which is advanced to enable the next reinforcing frame to be inserted into the trench.

In another aspect this invention resides broadly in a reinforced concrete wall including, interconnected reinforcing extending the length of the wall and concrete sections substantially divided by blocking means associated with the reinforcing.

In yet a further aspect of this invention, sealing apparatus may be provided to temporarily seal any gaps which are present between the blocking plates and the side or base walls of the excavation due to irregularities in the walls. The sealing apparatus may consist of a frame engagableslidably along the vertical slides and carrying at its sides or base flexible seals adapted to provide an effective barrier to the passage of concrete therebeyond. Preferably. the seals may be in the form of inflatable seals which are depressurised while the sealing apparatus is placed in the trench and which are inflated or filled after placement. The seals may be removable when the concrete adjacent the advancing face is partly set. In another aspect of this invention, intermediate sealing apparatus is provided to furnish a full-area barrier across the trench at a location remote from the vertical slides. The intermediate sealing apparatus may take the form of a frame with flexible seals along its sides or base. The flexible seals may be of the inflatable type or may be forced against the sides or base of the trench by actuators. The intermediate sealing apparatus may comprise a flexible tube which may be lowered vertically into the trench in the uninflated state, then inflated with pressurised fluid to block the cross-section of the trench.

In a further aspect, this invention resides in a method of producing a multi-tiered concrete retaining wall including:- (a) forming a concrete wall by the method described above; (b) excavating on one side of said wall to a depth equal to a selected fraction of the depth of the wall;

(c) placing ground anchors to anchor the top section of said wall to the ground on the unexcavated side of said wall; (d) subsequently excavating the partly-excavated side of said wall to a depth near the base of said wall;

(e) placing a trenching machine on the base of said excavation and excavating for a lower inground wall; (f) forming said lower wall by the method described above so that the top of said lower wall overlaps the bottom of said wall, and

(g) repeating steps (b) to (d) to form a tiered wall.

If further tiers of retaining wall are desired, they may be formed by repeating steps (b) to (e) as many times as is necessary. If required, the excavation of the depth of a wall may proceed in a number of stages, with the excavation proceeding to intermediate levels while the wall extending above these levels is retained by ground anchors.

-- BRIEF DESCRIPTION OF THE DRAWINGS --

In order that this invention may be more easily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention, wherein:-

FIG. 1 is a side view of a reinforcement frame;

FIG. 2 is a top view of the reinforcement frame in an excavation;

FIG. 3 is a front view of a sealing apparatus;

FIG. 4 is a sectional top view of the sealing apparatus;

FIG. 5 is a front view of an intermediate sealing apparatus; FIG. 6 is a top view of the intermediate sealing apparatus, and

FIG. 7 is a cross-sectional view of the construction of a two-tiered wall. -- DESCRIPTION OF THE PREFERRED EMBODIMENT --

As illustrated in FIG. 1, a cage-like reinforcing frame assembly 10 is fabricated by welding together vertical steel bars 11 and horizontal steel bars 12. A blocking plate 13 having channel-shaped formations 9 along its opposed vertical edges is welded to the ends of the horizontal steel bars 12 on one end of the reinforcing frame assembly, and spaced engagement bars 14 are welded to the other end of the reinforcing frame assembly such that they are in substantial alignment with the formations 9.

In FIG. 2, the blocking plate 13 on the reinforcing frame assembly 10 is shown in engagement with the engagement bars 15 attached to an adjacent reinforcing frame assembly 16 with the reinforcing frame assembly 10 within the trench 17 and encased in concrete 18.

FIGS. 3 and 4 illustrate front and top views of one form of sealing apparatus 30 for blocking the passage of concrete around the sides of a blocking plate. It comprises a frame

31 to which an inflatable edge seal 32 is attached by bolts 33. The sealing apparatus 30 is adapted for placement in a trench 34 in a deflated condition. The inflatable edge seal

32 is connected when required to a pressurised fluid supply by a connector 35 and a manifold 36 so as to expand the inflatable edge seal 32 and force it into operative sealing engagement with the walls of a trench whereby the flow of concrete around the sides of the blocking plate is prevented. The sealing apparatus 30 may be attached to the blocking plate 40 of a reinforcing frame 41 by means of engagement flanges 42 which slide into the returns 43 on the blocking plate 40. When so engaged, the apparatus 30 may be inflated and the trench 34 filled with concrete 44 around the reinforcing frame 41. The concrete is restrained from entering the open section of trench 45 by the inflatable edge seal 32 and the body of the sealing apparatus 30. The inflatable edge seal 32 is attached to the frame 31 by bolts 33 which engage threadably with tapping plates 46 within the inflatable edge seal 32.

The intermediate sealing apparatus assembly 50 shown in FIGS. 5 and 6 has a frame 51 comprising an end plate 52 and side plates 53. The side plates 53 may be hinged to the end plate 52 at their joints, or they may flex to accommodate the necessary movement of the side plates. A series of actuators 54 are attached to the side plates 53 by means of brackets 55 and pivot pins 56. Fluid is supplied to and withdrawn from the actuators 54 through flexible pipes 57 joining to commonsupply pipes 58 which are connected to suitable fluid pressurising apparatus. Extension of the actuators forces the free edges 59 of the side plates 53 into contact with the trench wall 60.

During construction of an inground reinforced concrete wall according to this invention, the trench 17 is excavated ahead of a reinforcing frame assembly 10 placed previously with its blocking plate 13 towards the advancing face of the trench. When a length of trench greater than the length of a reinforcing frame is excavated, a new reinforcing frame assembly 16 is hoisted above the open section of trench and the lower ends of the engagement bars 15 are slid into the upper ends of the slots on the blocking plate 13 so that the two reinforcing frame assemblies 10 and 16 are joined for their full length when the new reinforcing frame assembly 16 is lowered into the trench. Concrete is then poured into and around the new reinforcing frame assembly 16 at one side of the blocking plate 13 to extend the continuously reinforced wall.

If the trench walls or base are irregular, the sealing apparatus assembly 30 may be slid into engagement with the returns 43 on the blocking plate 40 of the new reinforcing frame 41, and the inflatable seals 32 pressurised to block the gaps before concrete is poured. If it is necessary to cast a section of wall which is shorter than available reinforcing frames, the intermediate sealing apparatus 50 may be utilised. The excess length of the reinforcing frame is cut off, leaving a short reinforcing frame 49 without a blocking plate. This short reinforcing frame 49 is slidable engaged with the previous reinforcing frame, and the intermediate sealing apparatus 50 is placed in the trench 60 at the forward end of the short reinforcing frame 49. The actuator 54 are extended to force the free edges 59 of the side plates 53 into contact with the sides of the trench 60. This contact provides a seal to restrict themovement of concrete along the trench, and also to prevent movement of the intermediate sealing apparatus 50 along the trench when it is subjected to the pressure of wet concrete on its end plate 52. Concrete may now be poured into and around the short reinforcing frame 49 to complete this panel. When the concrete has set, the intermediate sealing apparatus 50 may be removed from the trench after the actuators 54 have been retracted to withdraw the side plates 53 from contact with the sides of the trench 60.

If an excavation must be dug to a depth greater than the maximum depth capability of the trenching machine, a two- tiered wall may be constructed, as shown in FIG. 7. The trenching apparatus commences operation on the surface level 71 and excavates a trench in which a reinforced concrete wall 72 is formed. The material in the excavation is excavated to a second level 73 at a depth of less than half of the wall height, and ground anchors 74 are installed to retain the top part of the wall 72. Excavation then proceeds to a third level 75 near the bottom of the wall 72, and a second row of ground anchors 76 is installed to retain the lower part of the wall 72. The trenching machine than commences operation on the third level 75, excavating a trench in which a second reinforced concrete wall 77 is formed. Excavation proceeds to a fourth level 78, and a third row of ground anchors 79 is installed to retain the top portion of the second wall 77. A further cycle of excavation to a fifth level 80 and installation of ground anchors 81 completes the two-tiered wall. The procedure may be repeated to form further tiers of retaining wall if a deeper excavation is desired.

It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.

Claims

-- CLAIMS --

1. A reinforcing frame for reinforcing a concrete wall cast within a trench, said reinforcing frame including:- reinforcing (neans for the internal reinforcement of said concrete wall; blocking means co-operable with the opposed side walls of the trench for blocking flow of wet concrete cast about said reinforcing frame at one side of said blocking means, and connector means for connecting said reinforcing frame to an adjacent reinforcing frame.

2. A reinforcing frame as defined in Claim 1, wherein said blocking means comprises a blocking plate of width and height sufficient to substantially block said flow of wet concrete.

3. A reinforcing frame as defined in Claim 2, wherein the edges of said blocking plate terminate inwardly of the trench wall.

4. A reinforcing frame as defined in Claim 2, wherein the edges of said blocking plates abut said sidewalls whereby they are exposed in the finished wall.

5. A reinforcing frame as defined in Claim 2, wherein said blocking plates are placed intermediate to the opposed sides of respective said reinforcing frames.

6. A reinforcing frame as defined in Claim 2, wherein said reinforcing means is in the form of a rectangular cage and said blocking plate extends along one side of said cage.

7. A reinforcing frame as defined in Claim 6, wherein said connecter means comprises a slide connector attached to said blocking plate and engageable with a complementary slide connector attached to an adjacent reinforcing frame.

8. A reinforcing frame as defined in Claim 7, wherein said slide connector engages with a said complementary slide connector to limit relative movement between the two reinforcing frames in a horizontal plane.

9. A reinforcing frame as defined in Claim 8, wherein said slide connectors include bar like members on one frame and adapted to engage through overlapping loops projectingfrom an adjacent said reinforcing frame.

10. A reinforcing frame as defined in any one of Claims 7, 8 or 9, wherein said slide connectors on adjacent said reinforcing frames comprises complementary engageable means in the form of pairs of metal plates formed with matching reentrant profiles and said pairs of metal plates being attached to respective opposite sides of said reinforcing means.

11. A reinforcing frame as defined in Claims 7 to 10, wherein the clearances between said complementary slide connectors permits the joint therebetween to be filled with concrete or the like to lock the adjacent frames together.

12. A reinforcing frame as defined in any one of the preceding claims, wherein said reinforcing frames incorporate disposable inserts for forming recesses in the poured concrete for the location of tension members and anchor blocks associated with the anchoring of said concrete wall.

13. A method of forming a reinforced concrete wall including:-

(a) forming a trench by excavating a elongate trench; (b) providing a reinforcing frame including blocking means and connector means as defined above;

(c) inserting said reinforcing frame into the start of said trench; (d) placing concrete in and around said reinforcing frame on the side of said blocking means remote from the advancing face of said trench;

(e) connecting another reinforcing frame to the inserted said reinforcing frame; (f) placing concrete in and around said another reinforcing frame on the side of the blocking means thereon remote fromsaid advancing face of said trench; and (g) repeating the steps (e) and (f) as often as is required to complete said reinforced concrete wall.

14. Sealing apparatus for providing a temporary seal between blocking plates and the side or base walls of a trench, said sealing apparatus including a frame engageable slidably along the vertical slides of a reinforcing frame and carrying at its sides or base flexible seals adapted to provide an effective barrier to the passage of concrete therebeyond.

15. Sealing apparatus as defined in Claim 13, wherein said seals are in the form of inflatable seals which are depressurised while the sealing apparatus is placed in said trench and which are inflated or filled after placement.

16. Intermediate sealing apparatus for providing a temporary barrier to the flow of concrete along a trench beyond a reinforcing frame a location remote from vertical slides attached thereto, said intermediate sealing apparatus including a frame with flexible seals along its sides or base.

17. Intermediate sealing apparatus as defined in Claim 16, wherein said flexible seals are of the inflatable type.

18. Intermediate sealing apparatus as defined in Claim 16, wherein said flexible seals are adapted for urging against the sides or base of said trench by actuators.

19. Intermediate sealing apparatus for providing a temporary barrier to the flow of concrete along a trench beyond a reinforcing frame a location remote from vertical slides attached thereto, said intermediate sealing apparatusincluding a flexible tube which may be lowered vertically into said trench in the uninflated state, then inflated with pressurised fluid to block the cross-section of said trench.

20. A method of producing a multi-tiered concrete retaining wall including:- (a) forming a concrete wall by the method described above;

(b) excavating on one side of said wall to a depth equal to a selected fraction of the depth of the wall;

(c) placing ground anchors to anchor the top section of said wall to the ground on the unexcavated side of said wall; (d) subsequently excavating the partly-excavated side of said wall to a depth near the base of said wall; fe) placing a trenching machine on the base of said excavation and excavating for a lower inground wall;

(f) forming said lower wall by the method described above so that the top of said lower wall overlaps the bottom of said wall; and

(g) repeating steps (b) to (d) to form a tiered wall.

21. A method of forming a multi-tiered concrete wall as defined in Claim 20, wherein further tiers are formed by repeating steps (b) to (e) as many times as is necessary.

22. A method of forming a multi-tiered concrete wall as defined in Claim 20 or 21, wherein excavation of the depth of a wall proceeds in a number of stages, with the excavation proceeding to intermediate levels while the wall extending above said intermediate levels is retained by ground anchors.

23. A reinforcing frame substantially as hereinbefore described with reference to the accompanying drawings.