Method and apparatus for forming tunnels and tunnels formed thereby

Abstract

A method of forming tunnels(6), and tunnels formed thereby, said tunnels in one embodiment being of a form to carry transport routes (1) such as rail and road transport therealong. The method allows the tunnel to be formed from one or more access points (2) by allowing the tunnel structure (6) to be progressively extended out from the tunnel by advancing deck structures (24) along guide means (20) which are formed as part of a base structure (18). The deck structures (24) can also be used to support excavation equipment (28) and/or act as transport routes for access to the leading edge of the tunnel as it is formed. This greatly reduces the need for separate access and works to be provided adjacent to the tunnel as it is formed and therefore reduces the level of reinstatement works required after the tunnel has been formed.

Claims

1. A method of forming a tunnel under a surface, said method comprising the steps of forming at least one access point along the route of the said tunnel, forming at least first and second support bases in at least one direction away from the access point along said route, providing the support bases with guide means thereon, and a plurality of deck structures are advanced along the guide means to be supported by, and span between, the respective guide means to form at least the roof of at least a portion of the tunnel so that at least a portion of the said tunnel is formed outwardly from the said access point along said route wherein excavation work is performed to remove the material from the surface to the top face of the deck structures which have been advanced into position to allow the top face of the said deck structures to be available for the positioning of excavation apparatus thereon to perform further excavation work and/or for vehicles to move along the top face of the said deck structures to transport excavated material, and once the tunnel is formed, material is moved over the top face of the deck structures, to allow reinstatement work to be performed.

2. The method according to claim 1 wherein the said tunnel portion extends from the access point to an end of the tunnel or to a further access point spaced from the first access point.

3. The method according to claim 1 wherein a plurality of the tunnel portions are extended outwardly from the at least one access point in the direction of said tunnel route, said portions typically angularly offset around the access point.

4. The method according to claim 1 wherein at least first and second support bases are installed along access tunnels which are formed along the route and which extend from the access point to allow access for piling and support-base portions to be installed and for the guide means thereon to be exposed when required to allow the deck structures to be jacked along the same.

5. The method according to claim 4 wherein the at least first and second support bases includes a series of piles depending downwardly therefrom, one or more base units supported by the piles and on the upper and/or side walls of the base units guide means are formed.

6. The method according to claim 1 wherein at least one of the said first and second support bases forms at least part of the side walls of the tunnel structure when formed.

7. The method according to claim 1 wherein the deck structures are formed prior to advancement along the guide means, either being cast at or prior to delivery at the access point.

8. The method according to claim 1 wherein the deck structures are moved along the guide means by jacking means provided at the access point and/or at locations along the tunnel route from the access point to provide jacking force to move the deck structures into position.

9. The method according to claim 1 wherein the excavation is performed using one or a combination of tunnelling excavation in which a shield is provided at the leading deck structure and tunnelling excavation is performed, and/or open excavation in which the excavation work is performed along and downwardly from the surface.

10. The method according to claim 1 wherein the material to be removed is placed to a side of the route for subsequent use for reclamation or removal.

11. A tunnel formed using the method as described in claim 1.

12. A method according to claim 1 wherein tunnelling excavation is performed to form part of the excavation distance along the said route.

13. A tunnel and tunnel apparatus said tunnel formed from a support base including guide means formed thereon, side walls and a roof structure formed from one or more deck structures movable along and supported by the guide means of the support base, the support base includes at least first and second, spaced apart, portions, which include the guide means formed therein and the deck structures span the guide means formed in the respective support base portions and said tunnel includes at least one access point from which the deck structures are advanced along the guide means and from which at least part of the said tunnel apparatus extends and wherein during formation the top face of the deck structures which have been advanced into position form a support surface for positioning excavation apparatus thereon adjacent a location at which excavation is to be performed outside of the tunnel and/or for vehicles to move along the top face for movement of excavated material and once the tunnel is formed material is moved over the top face of the deck structures to allow reinstatement work to be performed.

14. The tunnel according to claim 13 wherein the tunnel includes, a first series of deck structures which define a first portion of the tunnel leading from the access point and a second series of deck structures, spaced from the first, which define a second portion of the tunnel leading from the access point.

15. The tunnel apparatus according to claim 13 wherein passageways are spaced apart along a substantially horizontal or vertical plane.

Description

(1) Specific embodiments of the invention are now described with reference to the accompanying drawings wherein;

(2) FIG. 1 illustrates in plan a tunnel formed in accordance with the invention in one embodiment;

(3) FIG. 2 illustrates a perspective view of the formation of the leading edge of a tunnel in accordance with one embodiment of the invention; and

(4) FIG. 3 illustrates a perspective view of the formation of a tunnel from an access point.

(5) Referring firstly to FIG. 1 there is illustrated in plan the formation of a tunnel structure 6 along a route 1 in accordance with one embodiment of the invention. There is shown an access point 2 which is located along the route of the tunnel which is to be performed. Typically the location and/or number of the one or more access points 2 will be determined with respect to any, or any combination, of the length of the tunnel, geological factors, access infrastructure, services which cross the route, depth of the tunnel and/or local and/or environmental concerns. It is also possible that there may be a number of access points provided along the length the tunnel route.

(6) A service road 4 may already be present or is formed so as to allow the transport of personnel, apparatus and removal and provision of materials to be performed via the access point and the road 4. In this case the tunnel 6 is shown as being formed in two directions 8,10 from the access point along the required route 1. In order to achieved this the following method steps can be performed with reference to FIGS. 1-3

(7) At the access point 2 a pit or shaft is excavated and this will ultimately form part of the tunnel structure 6 as well as acting as access means during the formation of the tunnel structure 6. From the pit or shaft, access tunnels 12, 12 and 14,14 are formed along the tunnel route, in the directions 8 and 10 respectively. From within the access tunnels piles 16 are formed downwardly and support base units 18 are placed along the access tunnels from the access point and are supported by the piles. Alternative methods can be used such as piling alone from the surface and/or placing a beam on top of the same.

(8) In the embodiment shown, guide means 20 are formed in the support base portions 22,22 which are formed along the access tunnels 12,12,14,14 and, when required the guide means can be exposed for use. The guide means are provided to have low friction whilst providing guidance for the movement of deck structures therealong and the guide means and or deck structures may include a low friction coating and/or guide tracks may be provided.

(9) Typically the guide means are only exposed soon before the advancement of the deck structures 24 in the directions 8 and 10 respectively from the access point 2. The deck structures are successively added and jacked along the guide means in the respective directions from the access point 2.

(10) Ahead of the leading deck structure 24 there is a need to excavate the material, typically soil and rock 26, which lies ahead of the deck structures. In FIGS. 2 and 3 the depth X of the material 26 is sufficiently shallow from the surface to the base of the cavity which is to be formed so as to allow open cut excavation to be performed from above the deck structure and it is shown in this case how the excavation work is performed by excavation apparatus and plant 28 which is located on the top faces 30 of the deck structures 24 which have already been advanced into position along the guide means from the access point. This therefore means that no disruption of the soil and environment to either side of the tunnel route 1 is required thereby minimising the excavation work required and the subsequent reinstatement work which is required.

(11) Furthermore, as shown in FIG. 1, transport vehicles 32 can also use the top surface 30 of the installed deck structures 24 as transport and access means between the leading edge of the tunnel structure as it is being formed and the access point 2, thereby minimising or avoiding the need for additional access roads to be formed to allow the movement of materials to service the formation and reinstatement of the tunnel structure 6.

(12) Also shown in FIG. 1 is that in the direction 8, rather than open cut excavation being performed ahead of the leading deck structure 24, tunnelling excavation is being used with a shield 34 provided in which the tunnelling is performed. Most typically this will be performed where the required depth of the tunnel below the surface is greater and/or where a top surface service such as a road, rail, river or canal 46 is already in existence and crosses the route 1 of the tunnel and there is a desire to avoid disruption of the same. Also, the tunnelling excavation may only be performed for part of the excavation distance and open excavation methods used for the remainder.

(13) If necessary, partition walls 36,38 may be installed in the interior of the tunnel cavity 40 to form, in the case shown in FIG. 3, first and second, separate tram passages 42, 44 in the tunnel cavity 40.

(14) Once the tunnel structure 6 is formed, the top surface 30 of the deck structures 24 can be overlaid with material 26 and then landscaped as required to provide the full reinstatement of the environment above the tunnel.

(15) It is envisaged that the invention will be of particular use when forming tunnels for use in carrying transport routes such as rail and road transport. For example, when forming roads an open trench can be formed and the tunnel structure is installed below and/or along the existing road. Conventionally the techniques used would take up a lot of space on the existing road and limit use of the same during construction works but this can be avoided in the apparatus and method of the current invention as it allows the tunnel structure to be installed without disruption of existing roads, and other installations such as crossroads, pipelines, cables etc. to be achieved.