WO2007012864A1

WO2007012864A1 - Ground reinforcement

Info

Publication number: WO2007012864A1
Application number: PCT/GB2006/002814
Authority: WO
Inventors: Timothy John Balderson
Original assignee: Linear Composites Ltd
Current assignee: Linear Composites Ltd
Priority date: 2005-07-27
Filing date: 2006-07-27
Publication date: 2007-02-01
Anticipated expiration: 2008-01-27
Also published as: EP1907635A1; GB0515416D0

Abstract

A ground reinforcement apparatus comprising a facing element having an outer surface and an inner ground engaging surface, in which the inner ground engaging surface comprises at least one socket, an attachment member and a strip. The strip may be looped around the attachment member. The attachment member may be received and engaged in the socket. The socket comprises a chamber partially closed by an annular lip to provide an opening. The lip includes two diametrically opposed rebates dimensioned to receive the attachment member and a strip looped thereon. The attachment member and the strip when passed through the rebates into the chamber of the socket may be rotated so that the attachment member engages the lip preventing withdrawal of the attachment member and the strip from the chamber of the socket.

Description

Ground Reinforcement

The present invention relates to an apparatus for the reinforcement of ground structures. The invention relates particularly to a method and apparatus for securing strips to a facing element of a ground reinforcement structure.

The use of strips to secure reinforced concrete or cementitious facing panels to a compacted soil or granular fill is well known. For example, the strips may be looped around steel or glass pins which are embedded within the facing panels.

The threading of long strips of polymeric material through a loop is difficult and time consuming.

WO 99/16979 discloses an arrangement wherein the polymeric strip is looped around a rod which is then inserted into an aperture in a first chamber within a facing element. The polymeric strip and the rod are then moved laterally from the first chamber into a second chamber which is dimensioned to receive and engage the rod.

According to a first aspect of the invention, there is provided a ground reinforcement apparatus comprising: a. a facing element having an outer surface and an inner ground engaging surface, in which the inner ground engaging surface includes at least one socket, b. an attachment member, and c. a strip, in which the strip may be looped around the attachment member, and in which the attachment member may be received and engaged in the socket, wherein the socket comprises a chamber partially closed by an annular lip to provide an opening, and in which the lip includes two diametrically opposed rebates dimensioned to receive the attachment member and a strip looped thereon, and in which the attachment member and the strip when passed through the rebates into the chamber of the socket may be rotated so that the attachment member engages the lip preventing withdrawal of the attachment member and the strip from the chamber of the socket. A facing for a reinforced ground structure is generally formed by an arrangement of panels or blocks composed of, for example concrete or other cementitious material. The ground structure can include any particulate material, such as for example soil, sand or gravel.

The panels may inter-engage or interlock to strengthen the facing and to distribute the load placed on individual panels. The facing is supported against the loads imposed by the ground structure by strips of polymeric material which are secured to the facing and which extend from the facing into the ground structure.

The strip may be composed of a polymeric material. In one embodiment, the polymeric strip comprises a strip of aligned or drawn fibres encased in a protective polymeric sheath. Preferably, the polymeric sheath is composed of PVC or polyethylene. The polymeric sheath may be formed by injection moulding.

Preferably, the width of the strip is less than the length of the attachment member. The strip may have a width which is less than about 95%, preferably less than about 90% , for example less than about 80% of the length of the attachment member. Preferably, the strip has a width of at least about 25%, preferably at least about 50%, for example at least about 70% of the length of the attachment member.

The attachment member can be a pin, an elongate rod or a beam. The attachment member is preferably cylindrical. The attachment member may be composed of polymers, glass, ceramic, carbon fibre composite material or a corrosion resistant metal. Preferably, the attachment member may be composed of glass.

In one embodiment, the attachment member has a length of at least about 80 mm, preferably at least about 90 mm, for example about 100 mm. Preferably, the attachment member has a length of less than about 150 mm, preferably less than about 120 mm, for example about 110 mm.

Preferably, the chamber of the socket is radially symmetrical. The chamber of the socket may be cup shaped or cylindrical. Preferably, the lip extends radially inwardly from the outer edges of the chamber and defines an opening with a diameter sufficient so that the strip may extend from the chamber to the exterior of the panel. Preferably, the opening provided by the Hp has a diameter which is sufficiently less than the length of the attachment member so that the member is securely engaged in use.

The lip may be formed from or include a reinforcement material. For example, the facing element may be formed from concrete and steel mesh or reinforcing rods may extend through the lip.

Preferably, the attachment member has a length which is at least about 5% greater, preferably at least about 10% greater, for example 20% greater than the diameter of the opening provided by the lip. Preferably, the attachment member has a length which is no more than about 50% greater, preferably no more than about 40% greater, for example no more than 35% greater than the diameter of the opening provided by the lip.

The diameter of the opening provided by the lip including the two diametrically opposed rebates is slightly greater than the length of the attachment rod. The diameter of the opening including the two diametrically opposed rebates is preferably at least about 5% greater than, preferably at least about 10% greater than, for example about 20% greater than the length of the attachment rod. The diameter of the opening including the two diametrically opposed rebates may be no more than about 70% greater, preferably no more than about 60% greater, for example no more than about 50% greater than the length of the attachment member.

Preferably, the socket in the facing element is formed from a mould or a cast. The mould or cast is preferably composed of polystyrene, PVC or low density polyethylene or other engineering polymer. The mould or cast corresponding in shape to the shape of the socket is positioned within the frame in which the facing is formed. Concrete or any other suitable material for forming the facing is poured into the frame.

In a further embodiment, the lip which extends radially inwardly from the socket is formed in situ during the process of forming the facing. Preferably, a mould or cast which is shaped so as to form the socket and the lip is positioned within the frame during formation of the facing. Alternatively, the lip is formed separately from the facing.

In a further embodiment the lip provides four diametrically opposed rebates. Preferably the four diametrically opposed notches of the lip are perpendicularly spaced from each other.

The width of the rebate is slightly greater than the radial dimensions of the attachment member. The width of the rebate may be at least about 5% greater than, preferably at least about 10% greater than, for example about 20% greater than the radial dimension of the attachment member. Preferably, the width of the rebate is no more than about 50% greater than, for example no more than 40% greater than the radial dimension of the attachment member.

According to a second aspect of the invention, there is provided a method for securing a strip to a facing element in accordance with the first aspect of the invention comprising: a. looping the strip around the attachment member, b. inserting the attachment member and the strip through the at least two diametrically opposed rebates provided by the lip into the socket, c. rotating the attachment member and the strip relative to the socket, and d. compacting soil or ground material against the strip adjacent to the inner surface of the facing to apply a movement preventing force to the strip.

Preferably, the soil or ground material which is adjacent to the inner ground engaging surface of the facing prevents the attachment member from rotating within the socket of the facing. The present invention therefore has the advantage that the facing element can be moved laterally if the panel slips without releasing the attachment member.

The attachment member is preferably rotated by less than about 180°, preferably less than about 90°, for example about 45° within the socket. The attachment member may be rotated by at least 10°, preferably by at least 25°, for example about 30°. In use, the rebates in the lip are preferably aligned substantially perpendicular to the orientation of the strip and the attachment member. Preferably, the rebates in the lip are vertical and the attachment member and strip are horizontal in use.

The method of the present invention has the advantage that threading of long ribbons of polymeric material is avoided. The method of the present invention is less time consuming and simpler to use than the conventional methods.

According to a third aspect of the invention, there is provided a ground reinforcement apparatus comprising: a. a facing element having an inner ground engaging surface providing first and second apertures connected by a channel, b. an attachment member, and c. a strip in which the strip may be looped in use around the attachment member so that the attachment member is engaged to the inner ground engaging surface of the facing element to secure the strip to the element, and in which the channel is arranged so that an end of a folded loop of the strip may be inserted into the first aperture, through the channel and out of the second aperture of the facing element, and wherein the attachment member may be inserted through the loop extending from the second aperture and wherein the second aperture is dimensioned to prevent withdrawal of the strip and the attachment member through the channel.

Preferably the channel terminates in a socket. Preferably the socket terminates in the second aperture.

Typically the channel terminates substantially centrally within the socket. Preferably the junction of the socket and the channel is an engaging shoulder. Typically the engaging shoulder is provided by an inner surface of the socket. Typically the mouth of the channel terminating at the socket is elongate. Typically the mouth of the socket is elongate. Typically the surface area of the mouth of the socket is larger than the surface area of the mouth of the channel terminating at the socket.

In a further embodiment, the chamber of the socket is radially symmetrical. The chamber of the socket may be cup shaped or cylindrical. The chamber of the socket may have a square cross-section. Typically the chamber of the socket is cuboidal in shape.

The diameter of the socket may be at least about 5% greater than, for example about 10% greater than the length of the attachment member. Preferably, the diameter of the socket is no more than about 50% greater than, preferably no more than about 40% greater than, for example about 20% greater than the length of the attachment member.

The channel preferably has a semi-cylindrical cross-section. The channel may be C-shaped in cross-section. In one embodiment, at least a portion of the channel is lined with a low friction polymeric material. Preferably, the entire channel is lined with a low friction polymeric material.

The strip may be composed of a polymeric material. In one embodiment, the at least one polymeric strip comprises a strip of aligned or drawn fibres encased in a protective polymeric sheath. Preferably, the polymeric sheath is composed of PVC or polyethylene. The polymeric sheath may be formed by injection moulding.

Preferably, the strip has a width of less than the length of the attachment member. The strip may have a width which is less than about 95%, preferably less than about 90% , for example less than about 80% of the length of the attachment member. Preferably, the strip has a width of at least about 25%, preferably at least about 50%, for example at least about 70% of the length of the attachment member.

The attachment member can be a pin, an elongate rod or a beam. The attachment member is preferably cylindrical. The attachment member may be composed of polymers, glass, ceramic, carbon fibre composite material or a corrosion resistant metal. For example, the attachment member may be composed of polypropylene, polyethylene, glass-filed polyethylene or any other suitable polymer.

Preferably, at least a portion of the channel extends parallel to the inner surface of the facing element. At least a portion of the channel may extend perpendicular to the inner surface of the facing element.

Preferably, the socket within the inner ground engaging surface of the facing is formed from a mould or a cast. The mould or cast is preferably composed of polystyrene, PVC or low density polyethylene. The mould or cast corresponding in shape to the shape of the recess is positioned within the frame in which the facing is formed. Concrete or any other suitable material for forming the facing is poured into the frame and the mould or cast is destroyed or moved from the frame once the concrete has set. In a further embodiment the channel is formed from a polymeric insert which is placed within the mould when the facing element is cast or moulded.

According to a fourth aspect of the invention, there is provided a method for securing a strip to a facing element in accordance with the third aspect of this invention comprising:: a. inserting a loop of the strip through the first aperture in the inner ground engaging surface of the facing element, through the channel into the socket and through the second aperture of the facing element, b. inserting the attachment member through a loop, and c. tensioning the strip so that the attachment member engages with the inner ground engaging surface of the facing.

The strip may be tensioned by pulling the free ends of the strip which extend out of the first opening in the facing element. The method of the present invention therefore has the advantage that the attachment member is quickly held in place by pulling the free end of the strip which extends out of the first opening of the facing. Threading of a long length of a polymeric strip is therefore avoided. The method of the present invention is simpler and less time consuming than the conventional methods.

Preferably, the soil or ground material is compacted against the strip extending from the first aperture of the facing element. The compacted soil or ground material preferably applies a movement restraining force to the strip and to the attachment member

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a view of the inner ground engaging surface of the facing element of the present invention from above;

Figure 2 shows a cross-sectional view of the facing element of the present invention along the axis A-A;

Figure 3 shows a view of the inner ground engaging surface of the facing element of the third embodiment of the present invention from above; and

Figure 4 shows a cross-sectional view of the facing element of the third embodiment of the present invention along the axis A-A.

With reference to Figures 1 and 2, the inner ground engaging surface of the facing element 2 comprises a socket 4. The socket 4 is radially symmetrical and may be cylindrical or cup shaped. The facing element 2 further comprises a lip 6 partially closing the socket 4. The lip 6 extends radially inwardly from the outer edges of the socket 4. The Hp 6 includes two diametrically opposed rebates 12. The lip 6 provides an opening 14 which has a diameter which is less than the diameter of the socket 4. The lip 6 is formed in situ with the facing element 2. The Hp 6 may include one or more reinforcing rods (not shown).

The attachment member 8 is a pin which may be composed of glass. The strip 10 is composed of polypropylene or other conventional material or composite. The width of the strip 10 is less than the length of the pin 8. The width of the strip 10 is less than the diameter of the opening 14 provided by the lip 6.

The length of the pin 8 is slightly less than the diameter of the lip 6 together with the two diametrically opposed rebates 12.

The socket 4 has a lower surface 16 and an outer edge 18. The gap 20 between the lower surface 16 of the socket 4 and the lip 6 is slightly greater than the radial dimensions of the attachment member 8.

In use, the strip 10 is looped around the pin 8. The pin 8 is inserted through the rebates 12 in the lip 6 and received within the socket 4. Once inserted the pin 8 is rotated about 90° relative to the socket 4 so that the rebates 12 are perpendicular to the strip 10. The lip 6 therefore prevents the pin 8 from being removed by pulling it from the socket 4. The soil or ground material may then be compacted against the inner ground engaging surface of the facing element 2 to apply a movement preventing force to the pin 8.

With reference to Figures 3 and 4, the inner ground engaging surface 34 of the facing element 2 comprises a second aperture 22 which provides a socket 24 and a first aperture 38. The socket 24 comprises an inner surface 26 and side surfaces 28. A channel 30 extends from the inner surface 26 of the socket 24 to the first aperture 38.

The channel 30 has a C-shaped cross-section. A portion 32 of the channel 30 extends parallel to the inner ground engaging surface 34 of the facing element 2. A further portion 36 of the channel 30 extends perpendicularly to the inner ground engaging surface 34 of the facing element 2. The channel 30 may be lined with a low friction polymeric material (not shown).

The second 22 and first 38 apertures have rectangular cross-sections. The diameter of the second aperture 22 is slightly greater than the length of the attachment member 8. The diameter of the first aperture 38 is slightly greater than the width of the strip 10.

In use, the polymeric strip 10 is looped and inserted through the first opening 38, through the channel 30 and into the socket 24 provided in the facing element 2. The polymeric strip 10 is pulled out of the second opening 22 in the facing element 2. A pin 8 is inserted through the loop of the polymeric strip 10. The polymeric strip 10 is tensioned by pulling on the free end extending from the first aperture 38 and the pin 8 is received within the socket 24 in the facing element 2. Soil or ground material is compacted against the inner ground engaging surface and prevents movement of the strip 10 and pin 8.

Claims

1. A ground reinforcement apparatus comprising: a. a facing element having an inner ground engaging surface providing first and second apertures connected by a channel, b. an attachment member, and c. a strip in which the strip may be looped in use around the attachment member so that the attachment member is engaged to the inner ground engaging surface of the facing element to secure the strip to the element, and in which the channel is arranged so that an end of a folded loop of the strip may be inserted into the first aperture, through the channel and out of the second aperture of the facing element, and wherein the attachment member may be inserted through the loop extending from the second aperture and wherein the second aperture is dimensioned to prevent withdrawal of the strip and the attachment member through the channel.

2. An apparatus as claimed in claim 1 in which the channel terminates in a socket.

3. An apparatus as claimed in either of claims 1 and 2 in which the channel has a semi-cylindrical cross-section.

4. An apparatus as claimed in any one of claims 1 to 3 in which the channel is C- shaped.

5. An apparatus as claimed in any one of claims 1 to 4 in which the channel is lined with a low friction polymeric material.

6. An apparatus as claimed in any one of claims 1 to 5 in which the junction of the socket and the channel is an engaging shoulder.

7. A ground reinforcement apparatus comprising: a. a facing element having an outer surface and an inner ground engaging surface, in which the inner ground engaging surface comprises at least one socket, b. an attachment member, and c. a strip, in which the strip may be looped around the attachment member, and in which the attachment member may be received and engaged in the socket, wherein the socket comprises a chamber partially closed by an annular lip to provide an opening, and in which the lip includes two diametrically opposed rebates dimensioned to receive the attachment member and a strip looped thereon, and in which the attachment member and the strip when passed through the rebates into the chamber of the socket may be rotated so that the attachment member engages the lip preventing withdrawal of the attachment member and the strip from the chamber of the socket.

8. An apparatus as claimed in claim 7 in which chamber is radially symmetrical.

9. An apparatus as claimed in either of claims 7 and 8 in which the lip includes a reinforcement member.

10. An apparatus as claimed in any one of claims 7 to 9 in which the diameter of the opening provided by the lip together with the two rebates is greater than the length of the attachment member.

11. An apparatus as claimed in any one of claims 7 to 10 in which the diameter of the opening provided by the lip is less than the length of the attachment member.

12. An apparatus as claimed in any one of claims 1 to 11 in which the attachment member is a pin, an elongate rod or a beam.

13. An apparatus as claimed in any one of claims 1 to 12 in which the attachment member is composed of glass.

14. An apparatus as claimed in any one of claims 1 to 13 in which the strip is composed of a polymeric material.

15. A method for securing a strip to a facing element using the apparatus as claimed in any of claims 7 to 11 comprising the steps of: a. looping the strip around the attachment member, b. inserting the attachment member and the strip through the at least two diametrically opposed rebates provided by the lip into the socket, c. rotating the attachment member and the strip relative to the socket, and d. compacting soil or ground material against the strip adjacent to the inner surface of the facing to apply a movement preventing force to the strip.

16. A method as claimed in claim 15 in which the compacting of the soil prevents rotational movement of the attachment member relative to the socket.

17. A method as claimed in either of claims 15 and 16 in which the attachment member is rotated by at least 45° relative to the socket.

18. A method for securing flexible polymeric strips to a facing for a ground reinforcement structure as claimed in any of claims 1 to 6, the method comprising the steps of: a. inserting a loop of the strip through the first aperture in the inner ground engaging surface of the facing element, through the channel into the socket and through the second aperture of the facing element, b. inserting the attachment member through a loop, and c. tensioning the strip so that the attachment member engages with the inner ground engaging surface of the facing.

19. A method as claimed in claim 18 in which the strip is tensioned by pulling on the free ends of the strip extending out of the first opening in the facing element.

20. A method as claimed in either of claims 18 and 19 further including compacting the soil or ground material adjacent to the inner ground engaging surface of the facing element.