TUNNEL LINING FASTENING DEVICES

Abstract: The disclosure relates to a two part cylindrical collet 10 having a head 11 at one end thereof with an encircling groove 13 around the head in which a ring ring 14 is located to hold the parts of the collet together. The collet has a tapered bore 15 which receives a tapered pin 17 to expand the collet. In order to hold the pin in the collet, the bore is formed with a succession of annular steps 16 along its length and the pin 17 is formed with a similar series of annular steps 18 to inter-engage with the steps 15.

Description: "TUNNEL LINING FASTENING DEVICES" This invention relates to tunnel lining fastening devices and is particularly although not exclusively applicable to fastening devices for use in tunnel linings as described and illustrated in our U.K. Patent No. 2004931. U.K. Patent Specification No. 2004931 described and illustrates a number of different fastening devices for locking pairs of tunnel lining segments together, the fastening devices being driven through projecting overlapping hoops on the respective segment ends. The device as disclosed comprises axially driven tapered pins or wedge elements which rely on friction to hold the pins or elements in place once driven into position or screw-threaded devices which require a very substantial torque in order to improse any significant degree of compression between the segment ends and also require a tool for turning the screw-threaded elements which, if it is a hand tool, can be difficult to operate at the concave surface of the tunnel lining if it is to have sufficient leverage. The invention provides a tunnel lining fastening device comprising a cylindrical collet having a piurality of separable elements, means to hold the elements together, the collet having a tapered bore and a tapered pin being provided to be driven into the tapered bore to expand the collet, there being i.nterlock-.ng means on the pin and bore to permit the pin to be driven into the bore but to resist extraction of the pin from the bore. The following is a specific description of one embodiment of the invention, reference being made to the accompanying drawings in which: Figure 1 shows three views of a fastening device for coupling tunnel lining segments in three different positions of assembly; and Figure 2 illustrates the separate components of the fastening device. Referring to the drawings, there is shown a fastening device for use in coupling tunnel lining segments and in particular for coupling segments of the form described and illustrated in our U.K. Patent No. 2004931. In that specification, tunnel lining segments are described which are coupled at their circumferential ends by means of pins. Each end of each segment has two semi-cylindrical grooves extending from the inner side part-way across the end of the segment one groove having a pair of projecting tensile hoops bridging the groove and the other groove having a single tensile hoop. The hoops on one segment end overlap with the corresponding hoops on an adjacent segment end and pins are driven into the grooves through the hoops to lock the segment ends together in compression. Our above patent specification described a number of forms of pin for that purpose and the following description relates to a further form of pin or gastening device for that purpose. Referring now to the drawings, there is shown a fastening device comprising a cylindrical collet 10 having a head 11 at one end thereof. The collet is formed in two separable elements 10a, lOb and the split line between the two elements which passes through the axis of the collet is indicated at 12. The head 11 of the collet is formed with an encircling peripheral groove 13 in which a spring ring 14 is located to hold the two elements together. the end of the collet remote from the head 11 is formed with a chamfer lOc to facilitate insertion of the collet end through the overrlapping hoops of the segment. As best seen in Figure 2 of the drawings, the collet 10 is formed with a bore 15 which tapers from the headed end of the collet to the chamfered end. The bore is formed with a multiplicity of annular steps 16 spaced along the bore and facing towards the chamfered end of the collet. A tapered pin 17 is engageable in the collet and is likewise formed with a multiplicity of annular steps 18 spaced apart along its length and which face towards the larger end of the pin. Thus when the pin is driven into the collet as illustrated in Figure 1 to expand the collet, the steps on the pin engage with the corresponding steps in the bore of the collet to resist movement of the pin out of the collet. In use the collet without the pin is driven through the overlapping hoops in a pair of segment ends and then a tapered pin is driven into the collet to expand the collet and, by acting on the hoope, to draw the segment ends into engagement and to compress and hold the segment ends together. By virtue of the inter-engagement of the steps on the pin with the on the bore of the collet, there is no tendency for the pin to work its way out of the collet.

Claims: CLAIMS: 1. A tunnel lining fastening device comprising a cylindrical collet (10) having a plurality of separable elements (10a,10b), means (14) to hold the elements together, the collet having a tapered bore (15) and a tapered pin (17) being provided to be driven into the tapered bore to expand the collet, there being interlocking means (16,18) on the pin and bore to permit the pin to be driven into the bore but to resist extraction of the pin from the bore. 2. A tunnel lining fastening device as claimed in claim 1 wherein the interlocking means comprise a number of annular shoulders (16) on the tapered bore (15) in the collet (10) spaced along the bore and facing towards the tapered end thereof and a number of corresponding annular shoulders (18) on the tapered pin (17) spaced along the pin and facing towards the larger end thereof to interlock with the shoulders on the bore. 3. A tunnel lining fastening device as claimed in claim 1 or claim 2 wherein the collet (10) has an enlarged head (11) at the end adjcent the larger diameter end of the bore in the collet. 4. A fastening device as claimed in claim 3 wherein the means for holding the elements of the collet together comprise a spring ring (14) seated in an encircling groove (13) around the periphery of the head (11). 5. A fastening device as claimed in any of the preceding claims wherein the collet comprises two separable elements (10a,IOb).

Inventors: HORNCY, THOMAS ERIC
Applicants: CHARCON TUNNELS LIMITED
Application year: 1983
Main classification: F16B13
IPC codes: F16B13, E21D11