Method for widening road, superhighway or railway tunnels, without interrupting the traffic

Abstract: The present invention relates to a method for widening road, superhighway or railway tunnels, without interrupting the traffic. The method comprises: a first step in which is carried out a boring for samples of the soil included between the theoretic profile of the widened tunnel to be made and that of the old existing tunnel, after having possibly operated on the soil included between the theoretic profile of the widened tunnel to be made and that of the old existing tunnel, by reinforcement operations on the boring front and precontainment operations of the widening cable, and a second step in which the final coating, comprising one or more arches of prefabricated quoins is laid, in samples, close to the boring front, according to "active vault" principle.

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for widening road, superhighway or railway tunnels, without interrupting the traffic. Due to the continuously increasing traffic demands, it is frequently necessary to widen road, superhighway or railway lanes in order to improve their traffic handling capabilities. Even if this problem can be solved in a comparatively easy manner, in the case of ways or lanes extending for the overall length thereof on surfaces, the solution of this problem is very complex and nearly impossible as the mentioned ways or lanes pass through tunnel constructions. In fact, a widening of an operating tunnel would involve great problems mainly related to the discomfort and safety of the users, as well as technical and operating problems related to widening works to be performed through a soil already disturbed by a preceding boring or excavation, in addition to problems related to the stress-strain conditions occurring as the widening operations are carried out. Known methods of enlarging tunnels are shown in EP 334.262 and in FR 2.230.806. SUMMARY OF THE INVENTION Accordingly, the aim of the present invention is to overcome the above mentioned problems, by providing a building method allowing to widen road, superhighway and railway tunnels, without interrupting the traffic. Within the scope of the above mentioned aim, a main object of the present invention is to provide such a method which is very safe for the users, while reducing to a minimum the user discomfort. Another object of the present invention is to provide such a method which is very flexible in fitting to any types of soils and stress-strain conditions occurring as said method is carried out. Another object of the present invention is to provide such a method which allows to fit the designed working times, independently from the type of soil and the involved stress-strain conditions, while reducing to a minimum the planned making cost and time, in order to consequently reduce to a minimum the traffic lane offsets and, accordingly, the user discomfort. Another object of the present invention is to provide such a method specifically designed for solving the problem of a possible presence, at the contour of the existing cable, of a soil band which has been already affected by plasticizing phenomena and which could be further disturbed. Yet another object of the present invention is to provide such a method allowing to widen the cross section of a tunnel without causing any damaging strains on the soil being bored, which strains would greatly stress the coating of the final widened tunnel, and involve differential surface settlings very dangerous for any existing constructions. According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a method for widening road, superhighway or railway tunnels, without interrupting the traffic, characterized in that said method comprises: a first step in which the soil included between the theoretic profile of the widened tunnel to be made and that of the old existing tunnel is bored, by samples; and a second step in which the final coating, comprising one or more arches of prefabricated quoins is laid, by samples, close to the boring front, according to the "active vault" principle. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the method according to the present invention will become more apparent hereinafter from the following disclosure of a preferred, though not exclusive, embodiment of said method, which is illustrated, by way of an indicative, but not limitative, example, in the accompanying drawings, where: Figure 1 is a schematic view illustrating the tunnel widening method according to the invention, the tunnel being longitudinally cross-sectioned through a vertical plane; Figure 2 is a cross-sectional view of Figure 1, taken along the section line II-II; Figure 3 is a schematic cross-sectional view similar to that of Figure 1 illustrating the quoin laying step alternating with the front boring step; Figure 4 is a cross-sectional view of Figure 3 according to the section line IV-IV; Figure 5 schematically illustrates a cross-section of a tunnel being widened, in the case in which a structural coupling element coupling the enlarged tunnel and the reverse arch of the existing tunnel is used; Figure 6 is a longitudinal cross-sectional view illustrating the tunnel of Figure 5; Figure 7 is a schematic view illustrating a cross-sectioned tunnel being widened, bu using a novel already cast-in reversed or inverted arch; and Figure 8 is a longitudinal cross-sectioned view illustrating the tunnel of Figure 7. DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the number references of the above mentioned figures, the method according to the present invention comprises substantially: a first step, in which the soil included between the theoretic profile of the widened tunnel 1 to be made and that of the old existing tunnel 2 is bored by samples (the size of which will depend on the involved soil features); a second step, in which the final coating, comprising one or more arches of prefabricated quoins 3, is laid, by samples (having a size mating the boring or excavation carried out in the preceding step) close to the boring front (i.e. at a maximum spacing of 2-3 meters), according to the "active vault" principle; and a third step, in which an optional foundation construction is made (inverted arch). If necessary, before the first method step, it would be possible to carry out a preparing step in which the soil included between the theoretic profile of the widened tunnel 1 to be made and that of the old existing tunnel 2 is processed, by performing reinforcement operations of the boring front and pre-containment operations on the widening cable, such as: a horizontal "jet grouting" or, alternatively, a mechanical pre-cutting or an advancing setting by valved and injected glass-resin tubes. Depending on the operation range of the preparing step, the subsequent boring and coating steps (i.e. the first and second steps), can be alternatively carried out several times, thereby allowing the operating ranges of subsequent preparing steps to properly overlap. During the first two steps, a traffic protecting steel shell 4 is used within the template of the old tunnel, the operating apparatus being driven and actuated above said steel shell. The gap 5 between the metal protecting shell and the existing-tunnel coating is filled-in by sound insulating and anti-impact materials. The steel shell 4, having a length corresponding to at least 4 times the diameter of the tunnel to be widened, will occupy a comparatively small space within said tunnel, thereby allowing the operating steps to be carried out without interrupting the vehicle traffic on the existing vehicle running lanes. At the end of the second operating step, the shell 4 will be caused to advance for the length of an operating range, and the different operating steps will be cyclically repeated to provide the desired final widened tunnel. The provision of the mentioned preparing step, as well as of the boring front reinforcement and cable pre-containment operations and, in the first and second steps, of the sample boring operations with an immediate construction of the final coating including the prefabricated concrete quoins 3, according to the mentioned "active vault" principle, constitutes a main feature of the invention which, by immediately stopping possible strains even at a short spacing from the boring front, will allow to overcome any problems related to a deforming response of the overall mass. The operating steps of the subject method will be disclosed in a more detailed manner hereinbelow. The mentioned preparing step is provided, as stated, to reinforce the boring front and to further carry out, depending on the operating geological-geotechnical environment, alternating recontainment operations on the cable, such as: the horizontal "jet grouting", the mechanical pre-cut or a setting of the advancing front by valved glass-resin tubes 13 injected on the contour of the cable. In the first step of the method according to the invention, the old tunnel widening boring and demolition operations are performed. These operations are carried out by samples of a reduced depth (from 60 to 150 cm) depending on the processed soil stress-strain conditions and the size of the prefabricated quoins 3, to provide the final coating (see the second operating step). If allowed, it would be possible to bore to a boring depth corresponding to a multiple of that of said quoins 3, and then lay several prefabricated quoins 3 arches. The apparatus for performing this boring operation would comprise one or more milling tools as well as heavy duty shearing elements for cutting the arch centres and metal elements forming the coating of the old tunnel to be demolished. Said apparatus would operate above said traffic protecting steel shell 4. In the second operating step the final coating of the widened tunnel, constituted by prefabricated arches of quoins 3, will be laid. The main building operations will be as follows: A) shipment of the quoins 3 to the boring front, by suitable conveyor belts arranged on a side of the widened tunnel; B) application, at the two cross ends, of the quoin 3 to be laid and, at the longitudinal end to be brought into contact with the already assembled coating arch, of a delayed setting epoxy resin; C) raising and locating the quoin 3 by a quoin locating apparatus, by driving at first those quoins to be arranged at a lowermost position, from the two sides of the tunnel, and then by arranging the other quoins in an ascending order, up to close the vault by the key quoin 3a; D) application of a beton filling between the prefabricated quoin 3 vault and the back material; E) pressurizing the key quoin 3a jack to cause the quoins 3 to perfectly adhere and immediately provide the required containment pressure on the contour mass of the widened tunnel, according to the "active vault" principle. Thus, it will be always possible, even at a subsequent time, to increase the pressure through the key quoin 3a, depending on the soil performance. In the third operating step, the foundation construction, if necessary, will be made by laying a simple coupling 20 between the coating of the new widened tunnel and the inverted arch 21 of the old tunnel, or by casting an inverted arch proper 22. During this third operating step, in order not to interrupt the traffic through the tunnel, two case of bending moments susceptible to split the resisting section of the prefabricated-quoins arch. The full mechanization of the operating steps of the subject method, together with the even advancing rate and small constructional time afforded thereby, will provide great advantages with respect to the building yard cost, as well as to the constructional rate. Moreover, the possibility of performing all the widening operations while protecting the road way by a steel shell thereunder the traffic can continue to safely run, will greatly reduce the user discomfort. Finally, the high flexibility of the subject method will allow to operate under any soil and stress-strain condition, in a fully safe environment. While the method of the invention has been disclosed and illustrated with reference to a preferred embodiment thereof, it should be apparent that the disclosed embodiment is susceptible to many modifications and variations all of which will come within the scope of the invention. cases must be considered: actually, in the case of a railway tunnel, after having widened this tunnel, the train traffic must be anyhow stopped in order to recover the rails. In the meanwhile the coupling construction coupling the final coating of the widened tunnel and the inverted arch of the old tunnel will be made or (as required by static requirements) the inverted arch will be cast; on the contrary, in the case of a single way road tunnel then, by suitably ordering the foundation making road lane widening operations, the traffic will run on at least a lane for each running direction. Likewise, in the superhighway tunnels of the double ways and two lanes for each running direction type, the traffic can always run on at least one or two lanes for each running direction, by suitably switching from a way to the other the foundation and road lane widening operations and, optionally, by switching the traffic, according to requirements, to the available traffic lanes. From the above disclosure and from the observation of the accompanying drawings, it should be apparent that the invention fully achieves the intended aim and objects. In particular, the fact should be pointed out that the method according to the invention allows to solve all the problems involved in widening road, superhighway or railway tunnels, while allowing a continuous traffic during the widening operations. In particular, the inventive method, with a possible provision of "cable precontainment operations", will reduce or eliminate any strains on the boring front and cable, thereby preventing a uncontrolled loosing of the mass being operated upon, and providing a very safe boring or excavation work. The application of a final coating comprising prefabricated quoin arches according to the "active vault" principle, carried out on reduced backgrounds and, accordingly, at a small spacing from the boring front, will overcome any requirements of making stabilizing operations of passive nature such as the use of the so-called spritz-beton and arch centres. The possibility, afforded by the inventive method, of pre-pressing the final coating, by the key quoin jack, will allow to recenter the loads, in the

Claims: A construction method for widening road, superhighway or railway tunnels, without interrupting a traffic flow, said method comprising a first stage in which a ground between a theoretical profile of a final widened tunnel 1 and that of an original tunnel 2, is excavated, in steps, to widen and demolish said original tunnel 2, a second stage, in which a final lining, consisting of one or more arches comprising a plurality of prefabricated segments 3, is immediately placed in steps at a maximum distance of 2-3 meters from an excavation face, wherein said second stage comprises: transporting said segments 3 to said face; applying a delayed setting epoxy resin on two ends of each segment 3 to be placed and on a side of each segment that will come into contact with an arch of lining that has already been erected; raising and positioning said segments 3 by a segment placing machine, placing the lowermost segments on each side of the tunnel first and then placing the segments in ascending order until the arch is completed with the placing of a key segment 3a; placing a jack in the key segment under pressure to make said segments adhere to each other perfectly and to immediately produce a necessary pre-stressed effect to confine the ground around the widened tunnel, wherein before said first and second stage, the ground between said theoretical profile of said final widened tunnel 1 and that of said original tunnel 2, is reinforced and preconfinement operations are performed around a cavity of said final widened tunnel 1, wherein said method comprises a third stage, in which a foundation construction is made, appropriate to said final widened tunnel 1, and wherein during said first and second stages and, during reinforcement of the face and preconfinement of the cavity of said final widened tunnel, a traffic protecting steel shell 4 is placed inside the profile of the original tunnel 2, above which all of the machinery employed in the execution of said first two stages and in the, execution of the reinforcement of the face and preconfinement of the cavity of said final widened tunnel 1 is operated and moved. A construction method, according to claim 1, wherein a hollow space between the original tunnel lining and said traffic protecting steel shell 4 is filled with a soundproofing and/or anti-shock material. A construction method, according to claim 1, wherein said traffic protecting steel shell 4 has a length equal to at least four times a diameter of said original tunnel 2 to be widened. A construction method, according to claim 1, wherein from time to time, after said second stage, said steel shell 4 is moved forwards for a length and said operational stages are repeated cyclically to provide said final widened tunnel 1. A construction method, according to claim 1, wherein the operations of said reinforcement of the face and preconfinement of said final widened tunnel 1 include a technique of horizontal jet grouting. A construction method, according to claim 1, wherein the operations of said reinforcement of the face and preconfinement of said final widened tunnel 1 include a technique of mechanical precutting. A construction method, according to claim 1, wherein the operations for said reinforcement of the face and preconfinement of said final widened tunnel 1 include a technique of reinforcement of the ground in advance by means of valved and grout injected fiber glass structural elements sub-horizontally inserted around the cavity.

Inventors: LUNARDI PIETRO, LUNARDI, PIETRO
Applicants: SPEA INGEGNERIA EUROP S P A, SPEA INGEGNERIA EUROPEA S.P.A.
Application year: 1998
Main classification: E21D9
IPC codes: E21D13, E21D9, E21D19