Arched cut-and-cover structure and method of its construction

Abstract

A cut-and-cover concrete tunnel structure ( 10 ) is provided with a lower concrete part ( 2 ) and an upper concrete or steel part ( 3 ) of the structure. The lower part ( 2 ) of the structure is constructed in unreinforced concrete, poured directly against and supported by a partly horizontal, partly inclined and approximately circular or elliptically shaped excavation surface ( 6 ′). The upper part ( 3 ) is arch shaped, constructed in reinforced (cast-in-place or precast) concrete or steel, and is of circular, elliptical or partly elliptical shape. This cut-and-cover structure allows a more efficient and less costly tunnel construction.

What is claimed is: 
     
         1 . A cut-and-cover tunnel structure for rail or road traffic or pipe lines, conveyor belts or cables, with a lower concrete part and an upper part of the structure, wherein the lower concrete part of the structure is supported directly against a partly horizontal, partly inclined excavation surface and wherein the upper part is an arch shaped upper part of the structure, constructed in reinforced, cast-in-place or precast concrete or in steel and is of circular, elliptical or partly elliptical shape. 
     
     
         2 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower concrete part is constructed in unreinforced concrete. 
     
     
         3 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower concrete part is constructed in non-metallic fiber-reinforced concrete. 
     
     
         4 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower part is constructed in steel-reinforced concrete. 
     
     
         5 . The cut-and-cover tunnel structure according to  claim 1 , wherein the inclined excavation surface is essentially circular or elliptically shaped. 
     
     
         6 . The cut-and-cover tunnel structure according to  claim 1 , wherein a waterproofing membrane is provided between the excavation surface and the lower concrete part. 
     
     
         7 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower concrete part rests directly on the excavation surface, without an intermediate material layer, in particular without a waterproofing membrane. 
     
     
         8 . The cut-and-cover tunnel structure according to  claim 1 , being a single tunnel structure or being a two tunnel structure with a common lower concrete part or being a structure providing more than two tunnels with a common lower concrete part. 
     
     
         9 . The cut-and-cover tunnel structure according to  claim 1 , being a tunnel structure separately housing two tunnels and comprising a single lower concrete part, a central wall and two upper parts supported by the central wall. 
     
     
         10 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower concrete part is functionally an arch-shaped structure (shown with dashed lines  2 ′). 
     
     
         11 . The cut-and-cover tunnel structure according to  claim 1 , wherein the lower concrete part extends to a level up to six meters above the center of the construction road pavement level. 
     
     
         12 . The cut-and-cover tunnel structure according to  claim 1 , wherein the upper part of the structure is provided with curvature radii between 4 m and 8 m, whereby the longer axis of the ellipse is vertical or near vertical and if present, inclined away from the central wall. 
     
     
         13 . The cut-and-cover tunnel structure according to  claim 8 , wherein each of the one, two or more tunnels contains rails, a rail support structure, platforms and tunnel equipment and in particular each of the tunnels provides an air volume adapted for high speed train operation. 
     
     
         14 . The cut-and-cover tunnel structure according to  claim 8 , wherein two or more tunnels are provided and the lower concrete part of the structure contains at least two drainage pipes collecting water from inside the tunnels and/or ground water penetrating the concrete structure; the drainage pipes and, if the case may be their inspection manholes, of each of the two or more tunnels being completely separated from the other one(s). 
     
     
         15 . The cut-and-cover tunnel structure according to  claim 1 , including at least one separate service and cable tunnel. 
     
     
         16 . The cut-and-cover tunnel structure according to  claim 9 , wherein the service and cable tunnel is arranged on top of the central wall. 
     
     
         17 . The cut-and-cover tunnel structure according to  claim 15 , wherein a service and cable tunnel is provided on one side or on both sides of the upper structure. 
     
     
         18 . The cut-and-cover tunnel structure according to  claim 15 , wherein a service and cable tunnel is provided on one side or on both sides within the lower concrete part. 
     
     
         19 . The cut-and-cover tunnel structure according to  claim 15 , wherein the service and cable tunnel is a cast-in-place or a precast reinforced concrete construction. 
     
     
         20 . The cut-and-cover tunnel structure according to  claim 9 , wherein the central wall comprises emergency connection openings between one tunnel and the neighboring tunnel, said openings being closable and openable by doors on both tunnel sides, in particular by sliding doors, thus forming a lock between the doors. 
     
     
         21 . The cut-and-cover concrete structure according to  claim 1 , wherein pressure wave relief measures in the form of at least one duct running parallel to the tunnel or to at least one of the two or more tunnels and connected to it or them are provided, the duct having openings to the outside for controlled pressure wave relief to the outside. 
     
     
         22 . The cut-and-cover tunnel structure according to any of  claim 1 , wherein a platform is provided within the lower concrete part of the structure by the concrete and wherein slots in the lower concrete part, preferably filled with a soft waterproof material bonded to the concrete, are provided. 
     
     
         23 . A method of construction of a cut-and-cover tunnel structure for rail or road traffic or pipe lines, conveyor belts or cables, with a lower concrete part and an upper part of the structure, wherein the lower concrete part of the structure is constructed by pouring concrete against a partly horizontal, partly inclined, preferably approximately circular or elliptically shaped excavation surface. 
     
     
         24 . The method according to  claim 23 , wherein a waterproofing membrane is provided between the excavation surface and the lower concrete part. 
     
     
         25 . The method according to  claim 23 , wherein the lower concrete part rests directly on the excavation surface, without an intermediate material layer, in particular without a waterproofing membrane. 
     
     
         26 . The method of  claim 23 , wherein excavation for the deepest part of the cut proceeds in two stages, providing in the first stage a horizontal or slightly inclined base as well slopes as on either side of the base starting from the ends of the base, and, in a second stage, creating the detailed curved excavation lines against which the lower part unreinforced concrete arch is directly poured, this pour closely following the detailed excavation procedure along the tunnel axis. 
     
     
         27 . The method according to  claim 23 , wherein the upper part is constructed in reinforced, (cast-in-place or precast) concrete and is placed on the lower concrete part. 
     
     
         28 . The cut-and-cover tunnel structure or the method according to  claim 1 , wherein the tunnel is a rail tunnel having a rail bed resting on lower concrete part, in particular a concrete rail bed, wherein water accumulating under the rail bed is caught by an array of draining means, in particular an array of draining geotextiles, and such water is conducted to the upper side of the rail bed, thus preventing a potential uplift of the rail bed.