Method of connecting two construction elements by using a deformable joint

Abstract: The invention relates to a constructional element such as a tunnel lining 1, part of which is shown in the drawing, comprising adjacent segments 2 and 3 which have facing surfaces 4 and 5 between which there is a joint 6 which is physically deformable under load. The joint comprises a toroidal body or tube 7 of substantially circular cross section received in complementary or semi-circular facing recesses (8, 9) in the surfaces 4 and 5 respectively, and comprises a flexible material such as polypropylene and which has means in the form of a nozzle 10 for gaining access to the interior of the body 7. The body 7 is initially filled with a fluid, which could be a liquid or gas, through the nozzle 10, which can then be maintained in the body 7 by closing the nozzle 10 as by a valve. When ground in which the tunnel is set has settled, the joint 6 is "locked up" by passing a flowable settable material such as a cementitious mortar material 11 from a grout pump into the body, which thereby displaces the fluid which passes out of the body 7 through an outlet which may be part of the nozzle 10, may be a separate nozzle, or may be the bleed valve.

Description: The invention relates to a method of connection, particularly to improvements in methods of connection of segmental concrete linings of for example a tunnel. Segmented rings of preformed concrete provide an immediate permanent lining of great strength for tunnels provided that they can be brought into close contact with the ground by grouting or otherwise. The lining segments are usually joined by radial knuckle or seat joints. It will be understood that there are generally two basic forms of tunnel linings. The two forms are bolted and boltless. The bolted lining is relatively rigid, whereas the boltless is relatively more flexible. The radial (seat) joints in both forms have no yielding contact areas, and in that sense are rigid. Because of this, in swelling or creeping ground or rock, failure of linings has occurred. GB 2 069 569A illustrates a sealing arrangement for a joint in a tunnel, and CH-A-574023 illustrates a prior art joint. It is accordingly an object of the invention to seek to mitigate this disadvantage. According to a first aspect of the invention there is provided a method of connecting two adjacent segments of a constructional element, comprising the steps of providing facing surfaces of the segments with a joint comprising a hollow body having a nozzle for introduction of fluid or settable material, filling the body with a fluid whereby it is rendered flexible and deformable whilst maintaining a desired spatial relationship between said facing surfaces of the segments, and rendering the joint substantially inflexible by replacing said fluid with a flowable settable material, characterised by the step of monitoring the settling of the medium in which the constructional element is placed by monitoring the internal pressure of the fluid via the said nozzle and introducing the said settable material once the monitoring indicates that the settling has maximised, whereby the constructional element is secured in its final rest position with its physical integrity intact. This provides a method whereby settling of ground round the constructional member is accommodated prior to rendering the joint set. The step of providing the settable material may comprise providing the joint as a toroidal member adapted to be received between facing surfaces of segments arranged to form a cylindrical member. This step provides for smooth operation and relative movement of the segments during settling. The method may comprise the step of providing complementary recesses in the respective facing surfaces adapted to receive the toroidal member. This provides a smooth seating for the member and for close contact of the facing surfaces of the segments which may comprise curved segments where the constructional member is a tunnel lining. According to a second aspect of the invention provides a method of constructing a tunnel, comprising using a method as hereinbefore defined. The body of the joint may comprise a plastic material; this provides a relatively inexpensive joint. Thus using the invention it is possible to provide a method of joining two adjacent segments of segmental concrete tunnel lining which segments have complementary facing recesses which accommodate a flexible cylinder, comprising first filling the cylinder with a fluid and then expelling said fluid and replacing it by a cementitious settable solid after a predetermined deflection of the lining has taken place. The method and constructional element embodying the invention are diagrammatically illustrated, by way of example, with reference to the accompanying drawing, which shows a cross-sectional view of a joint in accordance with the invention. Referring to the drawing, there is shown a constructional element such as a tunnel lining 1, part of which is shown in the drawing, comprising adjacent segments 2 and 3 which have facing surfaces 4 and 5 between which there is a joint 6 which is physically deformable under load. The joint comprises a toroidal body or tube 7 of substantially circular cross section received in complementary or semi-circular facing recesses 8, 9 in the surfaces 4 and 5 respectively, and comprises a flexible material such as polypropylene and which has means in the form of a nozzle 10 for gaining access to the interior of the body 7. In use, the tunnel lining 1 is necessarily installed below ground. The ground in practice settles around the tunnel lining 1 and this imposes a load on it and thus on the joint 6 which if rigid could be destroyed, thereby leading to loss of integrity of the lining and thus of the tunnel which could collapse. To accommodate this, using the invention the body 7 is initially filled with a fluid, which could be a liquid or gas, through the nozzle 10, which can then be maintained in the body 7 by closing the nozzle 10 as by a valve. As the ground round the lining settles, the joint 6 physically deforms or yields according to the external pressures imposed on it, whilst maintaining the desired spatial relationship between adjacent segments 2 and 3. This deflection can be as much as 150mm on both the X and Y axis. When the settling has maximised, which may be determined by taking readings over a period of time, which might be over several days or some months and will be of deformation of the segmental ring and by taking a pressure gauge on the nozzle 10, which then acts as a bleed valve, or on a separate bleed valve carried by the body 7 the joint 6 is "locked up" by passing a flowable settable material such as a cementitious mortar material 11 from a grout pump into the body, which thereby displaces the fluid which passes out of the body 7 through an outlet which may be part of the nozzle 10, may be a separate nozzle, or may be the bleed valve. The cementitious mortar 11, a high strength fine concrete, for example, completely fills the body 7 in the deformed joint 6 and thus when it sets produces a rigid articulated joint between the segments 2 and 3 in their "settled" position. The tunnel lining 1 is thus secured in its final rest position with its physical integrity intact. Using a method and constructional elements as herein described with reference to the drawing, a tunnel lining may be installed which moves as ground in which it is installed, swells and/or creeps, as is usually the case initially, and which can then be locked up by replacing the fluid with which the body is inflated with a flowable, settable cement. It will be understood that there may be modifications. For example, the body 7 may include a pressure relief valve for allowing fluid to be expelled from the body without rupturing same should the imposed pressure from the ground movement become excessive. It will also be understood that the invention provides a method of tunnel lining which is flexible and adaptable, and which can be varied to suit changes in ground conditions. Thus there is provided a preformed segmental lining in which the degree of flexibility of the lining can be adjusted to suit ground conditions. The basic joint is a radial knuckle joint. The radial (seat joint) has a concave recess formed in it which can accommodate a rigid, plastic or flexible cylinder. Thus the invention can: - a) use a rigid cylinder of high strength fine concrete. This produces a usual articulated jointed segmental lining; b) use nylon or similar plastic cylinder which produces a usual articulated jointed lining with the added flexibility of a "creeping" contact area between adjacent segments; and c) use a flexible cylinder, initially filled (inflated) with a liquid or gas which produces a yielding joint. When most of the deflection has taken place, the liquid or gas will be replaced by a cementitious mortar to produce a conventional articulated joint.

Claims: A method of connecting two adjacent segments of a constructional element, comprising the steps of providing facing surfaces (4, 5) of the segments (2, 3) with a joint (6) comprising a hollow body having a nozzle for introduction of fluid or settable material, filling the body with a fluid whereby it is rendered flexible and deformable whilst maintaining a desired spatial relationship between said facing surfaces of the segments (2, 3), and rendering the joint substantially inflexible by replacing said fluid with a flowable settable material, characterised by the step of monitoring the settling of the medium in which the constructional element is placed by monitoring the internal pressure of the fluid via the said nozzle and introducing the said settable material once the monitoring indicates that the settling has maximised, whereby the constructional element is secured in its final rest position with its physical integrity intact. A method according to Claim 1, characterised in that the step of providing said settable material comprises passing that material into the joint to displace fluid from the joint. A method according to either preceding claim, characterised by providing the joint (6) as a toroidal member adapted to be received between the facing surfaces (4, 5) of segments (2, 3) arranged to form a cylindrical element. A method according to Claim 3, characterised by the step of providing complementary recesses (8, 9) in the respective facing surfaces (4, 5) adapted to receive the toroidal member. A method according to any preceding claim, characterised by the segments (2, 3) comprising curved segments. A method of constructing a tunnel comprising the use of a method according to any one of Claims 1 to 5.

Inventors: THOMPSON JOHN FRANCIS, TUSCH KLAUS NORBERT, THOMPSON, JOHN FRANCIS, TUSCH, KLAUS NORBERT, THOMPSON, JOHN FRANCIS KINGSFORD
Applicants: COLEBRAND LTD, COLEBRAND LIMITED
Application year: 1993
Main classification: E21D11
IPC codes: E04B1, E21D11