CONNECTING DEVICE FOR CONNECTING CONCRETE SEGMENTS

Abstract: A connecting device for connecting segments of concrete or similar settable material, the device including a plastics connector part (1) of dumb-bell-like form and two housing parts (4) for receiving respective opposite portions (2) of the connector part. Each housing part has an internal tapered form so that, when the housing parts are set in opposed concrete segments to be connected and the connector part is inserted in the housing parts, the taper of each housing part causes the connector part to stretch thereby providing a tensile load between the opposite portions (2) of the connector part. Preferably, the taper has two angles of slope, the leading section causing the connector part to stretch and the hind section of taper causing the connector part to be trapped therein by relieving a measure of the stretch.

Description: CONNECTING DEVICE FOR CONNECTING CONCRETE SEGMENTS This invention relates to a connecting device for connecting concrete segments and is particularly concerned with connecting concrete segments edge-to-edge to form a tunnel or shaft lining. Tunnel and shaft linings are built up in rings of segments of pre-cast concrete, the segments being joined edge-to-edge and the rings being also joined together. Various known methods and devices are known for achieving this and a typical arrangement is disclosed in GB-A-1 498 625. However, there is a particular need to join segments together in a regular, reliable manner with a predetermined force whilst using the minimum of physical effort. In addition, there is a need to provide a joining or fixing system that has durability, is non-corrosive and is non-deleterius. According to one aspect of the present invention, there is provided a connecting device for connecting segments of concrete or similar setable material edge-to-edge, the device comprising a first connector part of dumb-bell-like form and two housing parts for receiving respective opposite portions of the connector part; characterised in that each housing part has an internal tapered form so that, when the housing parts are set in opposed concrete segments to be connected and the connector part is inserted in the housing parts, the taper of each housing part causes the connector part to stretch, thereby providing a tensile load between said opposite portions of said connector part. Preferably, each housing part has an internal tapered form with a leading section of taper of one slope and a hind section of taper of a second slope so that when the connector part is inserted as aforesaid, the leading section of taper of each housing part causes the connector part to stretch and the hind section of taper of each housing part causes the connector part to be trapped by relieving a measure of the stretch. According to another aspect of the present invention, there is provided a method for connecting segments of concrete or similar setable material edge-to-edge using a connecting device which comprises a first connector part of dumb-bell-like form and two housing parts for receiving respective opposite portions of the connector part; characterised by each housing part having an internal tapered form the method including setting the housing parts in opposed concrete segments to be connected, offering the concrete segments to one another and inserting the connector part in the housing parts, the taper of each housing part causing the connector part to stretch under load between said opposite portions. Preferably, the connector part and the housing parts are of a plastics material. The connector part may be of, for example, a high density filled nylon material or it could be a fibre reinforced nylon material. The connector part is intended to have high strength combined with high elasticity and the shape is such as achieve lines of stress on stretching that are substantially smooth. The housing parts on the other hand may be of a plastics material such as PVC. The housing parts, when viewed from a forward or leading section are of keyhole-shape and can be provided with external fins so as to be anchored in the concrete, with the leading section of each housing opening in the edge of the segment in which it is set. The keyhole section is of a depth to form a split tube. The connector part comprises rounded, opposite, end portions, which are the portions which are driven into the respective housing parts, interconnected by a web portion extending in use between the two housing parts and passing between the split portions of the tubes of the keyhole sections . To facilitate initial retention of the connector part upon manual insertion in the housing parts, small pins or other protruding members may be provided on the connector part to allow the connector part to jam against the insides of the housing parts near the splits. The operative is then in a position to have both hands free to drive the connector part home with a hammer, for example. To assist in locating the edge of one concrete segment onto the edge of another to be joined to it, a locating means can be provided. This can be in the form of a shear pin, which is inserted in a rearmost portion of the hind section of one of the housing parts, the shear pin having a body portion extending, at right angles to the split, out of the housing part in which it is inserted to lie along a groove provided in the edge of the concrete segment to be joined to an adjacent edge of the other segment. By providing a corresponding groove in the adjacent concrete segment, but of a greater length, the former concrete segment holding the shear pin can be slid into edge-to-edge position and aligned with the latter concrete segment before they are joined by the connector part with the housing parts facing each other. The invention also extends to a tunnel or shaft lining segment incorporating at least one connecting device according to the invention. Preferably, there are four housing parts per segment. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: - Figure 1 is a perspective view of the connector part, Figures 2A, 2B and 2C are respectively a plan view, side view and underneath view of the connector part, Figures 3A-3Ξ are views of one of the housing parts, which are all identical, Figure 3A being a side view, Fiςrure 3B being a front view, Figure 3C being a section taken along line A-A in Figure 3A, Figure 3D being a section taken along line B-B in Figure 33 and Figure 3E being a section taken along line C- C in Figure 3B, Figures 4A and 4B are respectively an end view and a side view of a preferred form of shear pin, Figure 5 is a diagrammatic view illustrating the arrangement of two adjacent concrete segments to be connected, with the two housing parts set in the concrete and the shear pin in place, - 3 - Figure 6 is a diagrammatic view illustrating the two concrete segments ready for alignment, and Figure 7 shows the two concrete segments aligned and joined by the connecting device. Figures 1, 2A, 2B and 2C show the first connector part 1 of the connecting device, the connector part 1 being of dum -bell -like form with rounded end portions 2 which are each provided with a taper calculated to work in a desired fashion with tapers provided inside the housing parts (to be described) . Also visible are pins 3 which are provided simply to hold the connector part against the insides of the housing parts before the connecter part is driven home. As mentioned previously, the connector part 1 is of high strength plastics material with high elasticity and it has a substantially constant elastic load/stretch characteristic so that, upon a tensile effort being applied to the ends 2 of the connector part 1, which is what occurs when it is being driven into the housing parts, the load reaches and sustains a substantially constant level, which is designed to be below the breaking load of the concrete segments. Tests have shown, for example, that consecutive tensile stresses to stretch the connector part lengthwise result in a substantially constant load in excess of one tonne each time between the ends 2. Referring now to Figures A and 3B, in which one of the identical housing parts 4 is illustrated, the housing part 4 has an internal cross- section which is of substantially keyhole- shape with external fins 5 which are designed to - o self -locate in the concrete and which hold the housing 4 in place, without any tendency to be pulled out, after the concrete of the segment has set. A front side of the housing part 4 is provided with out-turned flanges 6 which are intended to align with the front of an edge face of the mould in which the concrete segment is to be cast. The keyhole shape as can be seen provides an open slot 7 at the front of the housing part 4, whilst the rear of the housing part 4 has the rounded part of the keyhole, in which one of the end portions 2 of the connector part 1 is to be trapped, the web of the connector part 1 extending out of the front slot 7. Referring more particularly to Figure 5, viewed in another dimension, each housing part has an internal tapered form running the length of the keyhole. This taper is applied on the two edges 8 providing the transition between the rounded part of the keyhole- shape and the flared or split front end 7. As illustrated on the right-hand side of Figure 5, a leading section of taper 8A is of one slope and a hind section of taper 8B has a second slope, the first, leading taper 8A being steeper than that of the hind section of taper 8B. Reverting to Figures 4A and 4B, a preferred form of shear pin 9 is illustrated which is provided with a collapsible and/or resilient lead portion 10 for insertion in the rearmost part of the hind section of one of the housing parts 4 (see the arrow beside Figure 4B) , the rear 11 of each housing part 4 being closed. The shear pin 9 can be made of the same material as the connector part 1. Referring especially to Figures 5, 6 and 7, the housing parts 4 are set in respective concrete segments 12, 13 with each keyhole opening into the intrados of the segment. In a tunnel lining, each concrete segment will be provided, e.g., with four such housing parts 4, two on each transverse edge. The shear pin 9 will be punched into the base or rear end 11 of alternate housing parts 4 and this arrangement allows for the segment to be rotated, i.e. it is not handed. This is of particular advantage when working in a tunnelling construction environment. As shown in Figure ό, the two segments 12 and 13 are offered to one another with opposed housing parts 4 closely adjacent. The keyhole section is clearly illustrated. As the two concrete segments are urged into alignment towards the Figure 7 condition, the shear pins 9 assist in such location. Incidentally, the oval shape of the main body of the shear pin 9 (see Figures 4A and 5) takes into account that the joint between the concrete segments has packing added to it. As viewed in Figure 5, the shear pin 9 sits in opposed grooves 14 in the respective segments 12 and 13. Once the opposed housing parts 4 are in successful alignment, the connector part 1 is located in the two housing parts 4, initially manually and being held in place e.g. by the pins 3. Then the connector part is forcibly driven further into the keyholes of the connector parts 4, the tapers on the end portions of the connector part 1 working with the tapers 8A and 8B of the connector parts. The tapers 8A apply a tensile stress to the connector part 1 thereby to stretch it and the tapers therefore provide - a - greater tensile effort as the connector part 1 is driven further in. The shear pins 9 assist in preventing misalignment of the housing parts 4 which otherwise might happen because of the hammering effect of driving the connector parts 1 in the housing parts 4. As mentioned previously, the hind section of taper 8B of each housing part causes the connector part 1 to be trapped by relieving a measure of the stretch or tensile effort applied to it so that it effectively snaps into the hind sections of the housing parts 4. This is the condition illustrated in Figure 7. As illustrated in Figure 5, it will be noted that the housing parts 4 are set some distance back from the major faces of the concrete segments 12 and 13, a recess 15 to a standard depth being provided in the intrados of each segment to allow the entry of the connector part 1. If desired, once the connections between the concrete segments have been made, the hollows at the connecting locations can be filled over by concrete to the required depth. However, since all of the components are of a plastics material, there would not normally be the need to fill in with concrete since, as compared with known systems, there is no exposed steel, thereby providing a durable system without any corrosion problem. The plastics materials used are intended to have a longevity to provide a long life segmental system. To give some idea of relative dimensions, the overall length of each connector part 1 can be of the order of 75 mm, the web of the connector part 1 can be of the order of 8 mm thick, the depth of the housing part 4 can be of the order of 50 mm and the maximum fin width across the housing part can be of the order of 45 mm. It will be noted from in particular Figure 7 that the end portions 2 of the connector part 1 are flattened so that chambers 16 are provided in the housing parts 4 to allow space for release of detritus and other matter. Finally, the connector part 1 can be moulded in such a way to provide a fault line 1A located around the perimeter which also assists the operator in allowing the connector part 1 to be held initially in the housing parts 4, thereby leaving the operator with free hands for the subsequent driving in of the connector part.

Claims: CLAIMS : 1. A connecting device for connecting segments of concrete or similar setable material edge-to-edge, the device comprising a first connector part (1) of dumb-belllike form and two housing parts (4) for receiving respective opposite portions of the connector part; characterised in that each housing part (4) has an internal tapered form so that, when the housing parts are set in opposed concrete segments (12, 13) to be connected and the connector part (1) is inserted in the housing parts, the taper of each housing part (4) causes the connector part (1) to stretch, thereby providing a tensile load between said opposite portions of said connector part. 2. A device according to claim 1, wherein each housing part (4) has an internal tapered form with a leading section (8A) of taper of one slope and a hind section (8B) of taper of a second slope so that when the connector part (1) is inserted as aforesaid, the leading section (8A) of taper of each housing part causes the connector part to stretch and the hind section (8B) of taper of each housing part causes the connector part to be trapped by relieving a measure of the stretch. 3. A device according to claim 1 or 2 , wherein said connector part (1) is of a plastics material. 4. A device according to claim 3, wherein the connector part (1) is of a high density filled nylon material. 5. A device according to claim 3, wherein said connector part (1) is of a high density fibre reinforced nylon material. 6. A device according to any one of the preceding claims, wherein the housing parts (4) are of a plastics material. 7. A device according to any one of the preceding claims, wherein each housing part (4) , when viewed from a forward or leading section, is of keyhole-shape and is provided with external fins (5) for anchoring in the concrete or other setable material with the leading edge of each housing opening in the edge of the segment (12, 13) in which it is set, the keyhole section opening into a split (7) to allow passage of a portion of said connector part (1). 8. A device according to any one of the preceding claims, wherein said connector part (1) comprises rounded, opposite, end portions (2) , which are the portions which are driven into the respective housing parts (4) , in use, interconnected by a web portion extending in use between the two housing parts. 9. A device according to any one of the preceding claims, wherein protruding members (3) are provided on the connector part to allow the connector part to jam against the insides of the housing parts upon entry. 10. A device according to any one of the preceding claims, and comprising a locating means (9) inserted in a rearmost portion (11) of the hind section of one of the housing parts (4) , the locating means having a body portion (10) extending out of the housing part in which it is inserted to lie in use along a groove provided in the edge of the segment to be joined to an adjacent edge of the other segment. 11. A tunnel or shaft lining segment (12, 13) incorporating at least one connecting device according to any one of the preceding claims. 12. A method for connecting segments of concrete or similar setable material edge-to-edge using a connecting device which comprises a first connector part (1) of dumb-bell-like form and two housing parts (4) for receiving respective opposite portions of the connector part; characterised by each housing part having an internal tapered form the method including setting the housing parts (4) in opposed concrete segments (12, 13) to be connected, offering the concrete segments to one another and inserting the connector part (1) in the housing parts, the taper of each housing part (4) causing the connector part to stretch under load between said opposite portions. 13. A method according to claim 12, wherein each housing part (4) has an internal tapered form with a leading section (8A) of taper of one slope and a hind section (8B) of taper of a second slope so that when the connector part (1) is inserted as aforesaid, the leading section of taper of each housing part causes the connector part (1) to stretch and the hind section of taper of each housing part causes the connector part to be trapped by relieving a measure of the stretch. 14. A method according to claim 12 or 13, wherein the connector part (1) and the housing parts (4) are of a plastics material, the connector part having high stremgth combined with high elasticity and being shaped so as to achieve lines of stress on stretching that are substantially smooth. 15. A tunnel or shaft lining of segments of concrete or similar setable material assembled in accordance with the method of claim 12, 13 or 14.

Inventors: SMITH CHRISTOPHER RICHARD, THOMAS NORMAN STANLEY, SMITH, CHRISTOPHER, RICHARD, THOMAS, NORMAN, STANLEY
Applicants: BUCHAN C V LTD, SMITH CHRISTOPHER RICHARD, THOMAS NORMAN STANLEY, C.V. BUCHAN LIMITED, SMITH, CHRISTOPHER, RICHARD, THOMAS, NORMAN, STANLEY
Application year: 1997
Main classification: E21D11
IPC codes: E21D11