An excavating method and apparatus for constructing the base of a tunnel

Abstract: An excavating apparatus for constructing, remaking, reinforcing or restoring any part of the base of a tunnel, such to provide an inverted arch (18) or resting piers structure adequate for sustaining the tunnel (11), comprises a power driven trencher excavating means (20) so restrained as to accomplish a combined movement of: oscillation about an axis substantially parallel to the longitudinal axis of the tunnel; sliding in a direction perpendicular to said axis; and transverse horizontal translation together with said oscillation axis, along a horizontal guide means (10) extending transversely in the tunnel (11). There is also disclosed an excavating method making use of such an apparatus.

Description: Field of the invention The present invention refers to an excavating method and apparatus for constructing the base (inverted arch or resting piers) of a new, or an already existing tunnel to be widened or restructured. Background of the invention At present, projects of road, railway and tube railway network, make increasing provisions for tunnels which should have a reduced environmental impact. Therefore, efforts are made to find quick, safe and inexpensive methods of constructing tunnels. It is often necessary to restore existing tunnels. Also, many tunnels have to be widened, as it is not always possible or convenient to split the carriageway or deviate the road and construct a new tunnel of the required size. In view of the above problems and requirements, there have been recently proposed new systems and motors for constructing or restructuring the vault of a tunnel, being this a new tunnel or an existing one to be widened or restored. Examples of said methods and apparatuses are given in EP-A-0 538 718, EP-A-0 557 805 and EP-A-0 394 806. Excavation of successive lengths of the soil or the structure of the already existing tunnel is carried out while constructing the new wider vault. Summary of the invention An object of the present invention is to provide an excavating method and an apparatus for constructing, remaking, reinforcing or restructuring any length of the base of the tunnel, so as to provide a inverted arch or resting pier structure bearing the tunnel adequately as a function of its section. Where the vault is to be widened, obviously the inverted arch will also have to be widened accordingly or the resting piers will have to be fitted at a different location. According to an aspect of this invention, the above and further objects which will be more apparent hereinafter are attained by the provision of an excavating apparatus for constructing, remaking, reinforcing or restoring any part of the base of a tunnel, such to provide an inverted arch or resting piers structure adequate for sustaining the tunnel and suitably sized as a function of the section of the tunnel, characterized by comprising a trencher excavating means driven by driving means and so restrained as to accomplish a combined movement of: oscillation about an axis substantially parallel to the longitudinal axis of the tunnel; sliding in a direction perpendicular to said axis; and transverse horizontal translation together with said oscillation axis, along a horizontal guide means extending transversely in the tunnel. In accordance with another aspect of the present invention, there is provided an excavating method using a trencher excavating means as cited, characterized in comprising the steps of: a) locating the trencher excavating means proximate to the foot of the tunnel; b) excavating the foot of the tunnel by advancing said trencher means in the soil downwards and outwards of the tunnel; c) translate said trencher means in a substantially horizontal direction across the base of the tunnel, providing one of said transversal base trenches; d) shifting longitudinally said trencher means a predetermined distance; and e) repeating cyclically steps (a) to (d) providing a series of trenches for a corresponding series of grade beams forming said inverted arch structure adapt to the section of the tunnel. Brief description of the drawings For a better understanding of the method and apparatus of the present invention, reference is made to the following detailed description of an exemplary embodiment considered in combination with the accompanying drawings in which: FIG. 1 is a cross-sectional view of a tunnel in which there is located an apparatus in accordance with the present invention; FIGS. 2 and 3 are a longitudinal sectional view and a plan view, respectively, of the tunnel and apparatus of FIG. 1; FIGS. 4A to 4F schematically depict a sequence of operations in accordance with the method of this invention in widening a tunnel; the operations are carried out by an apparatus according to this invention; and FIGS. 5 and 6 are cross-sectional views showing the final result of the method. Detailed description of the invention The following description particularly relates to the remake of the base (inverted arch or resting piers) of an existing tunnel. It is understood that the described method and apparatus are capable of being suitably employed for constructing a completely new tunnel. With reference initially to FIGS. 1, 2 and 3, numeral 20 designates an excavating cutter, preferably a chain trencher as known from EP-A-0 407 934. Trencher 20 is movable along a substantially horizontal guide 10 disposed transversally within the tunnel 11, in order to excavate trenches then to be filled with concrete to form the basis of the tunnel. Still referring to FIGS. 1 to 3, horizontal guide 10, that can rest on the floor by means of extensible feet 12, is transportable in the longitudinal direction of the tunnel by a crawler track vehicle 13. The trencher 20, which is for excavating trenches in the transverse direction of the tunnel as described hereinafter, is slidable along a guide 15 in a substantially vertical and transverse plane. Guide 15 is rotatably mounted about a substantially horizontal and longitudinal axis to a carriage 14 sliding along the horizontal guide 10. The length of the horizontal guide 10 may indifferently be such as to span substantially the whole width of the tunnel, as shown in FIG. 1, or, in the event of widening works as depicted in FIGS. 4a to 4F, may be limited to a portion of the tunnel so as to work on one side while allowing traffic to pass along the other side. Owing to the above described arrangement, the excavating trencher 20 is driven by suitable driving means 16 (not described in detail as well known to those skilled in the art) and is capable of accomplishing a combined movement of: oscillation about a longitudinal axis; sliding in a direction perpendicular to said axis; and transverse horizontal translation together with such oscillation axis. In this way, the trencher can excavate a transversal trench 17 to form the base of the tunnel (inverted arch or resting piers) following the sequence of operations illustrated in FIGS. 4A-4F. Referring particularly to these drawings, the trencher is initially positioned proximate to the point of junction between the bottom of the tunnel or gallery 11 and the inverted arch 18 (FIG. 4A). The trencher is then extended (FIG. 4B) to demolish the foot of the tunnel and the inverted arch, excavating the soil or rock. The trencher is oscillated outwardly (FIG. 4C) excavating a side portion 17a for the foot or resting pier of a new section of the tunnel. Then, the trencher oscillates and translates as a unit with carriage 14 along the horizontal guide 10. The result is the excavation of a trench suitably shaped and sized as to accommodate a subsequent casting of concrete. Upon hardening, the concrete will form the full or half grade beam. Optionally, only the seat for the resting piers can be formed (FIG. 6). With a half grade beam, overall structural continuity is attained on completion of the construction of the second half-beam. The contact surface is cleared and, optionally, reinforcement bars (not shown) are inserted and cemented. Once the base or the excavation for casting are ready, the equipment is shifted longitudinally by the tracked vehicle 13 to locate the trencher 20 at a predetermined distance to carry out a new excavation and casting. Repetition of these steps yields a base of resting piers or inverted arch which may be continuous or discrete, depending on whether the grade beams are attached forming a single monolithic body or spaced apart. Such a base is well suited for withstanding the load the vault transmits to the tunnel. As will be appreciated, the possibility of oscillating upwards and outwardly allows to form excavations (and so bases) also of complex shapes, as is sometimes required by the project. In further detail it is deemed that the above described method is applicable almost in any situation, such as for example: restructuring existing tunnels eventually modifying or reinforcing the inverted arch or resting piers; the widening of existing tunnels remaking a larger inverted arch or fitting the resting piers in a different position under the new vault; constructing of new tunnels, constructing the inverted arch or resting piers in accordance with the method of this invention instead of presently known methods. It is to be understood that the embodiment described above is merely exemplary and that persons skilled in the art may make many modifications without departing from the invention as defined by the appended claims.

Claims: An excavating apparatus for constructing, remaking, reinforcing or restoring any part of the base of a tunnel, such to provide an inverted arch (18) or resting piers structure adequate for sustaining the tunnel and suitably sized as a function of the section of the tunnel (11), characterized by comprising a trencher excavating means (20) driven by driving means (16) and so restrained as to accomplish a combined movement of: oscillation about an axis substantially parallel to the longitudinal axis of the tunnel; sliding in a direction perpendicular to said axis; and transverse horizontal translation together with said oscillation axis, along a horizontal guide means (10) extending transversely in the tunnel (11). An apparatus as claimed in claim 1, characterized by being mounted onto a transport means (13) movable in the longitudinal direction of the tunnel. An apparatus as claimed in claim 1, characterized in that said trencher excavating means (20) is slidably mounted in a substantially vertical transverse plane to a guide means (15) oscillating about an oscillation axis substantially parallel to the longitudinal axis of the tunnel, said oscillation axis being part of a carriage (14) slidable along said horizontal guide means (10). An apparatus as claimed in claim 1, characterized in that the length of said horizontal guide means (10) is such to span substantially the whole width of the tunnel (11). An apparatus as claimed in claim 1, characterized in that said the length of said horizontal guide means (10) is such to span a fraction of the whole width of the tunnel (11). An excavating method using a trencher excavating means (20) according to any of the preceding claims, characterized in comprising the steps of: a) locating the trencher excavating means (20) proximate to the foot of the tunnel (11); b) excavating the foot of the tunnel by advancing said trencher means (20) in the soil downwards and outwards of the tunnel; c) translate said trencher means (20) in a substantially horizontal direction across the base of the tunnel, providing one of said transversal base trenches (17); d) shifting longitudinally said trencher means (20) a predetermined distance; and e) repeating cyclically steps (a) to (d) providing a series of trenches (17) for a corresponding series of grade beams forming said inverted arch structure (18) adapt to the section of the tunnel (11). A method as claimed in claim 6, characterized in that said step (b) comprises the step of: b1) oscillating said trencher means (20) about an axis substantially parallel to the longitudinal axis of the tunnel to create larger zones (17a) at the foot of the tunnel (11) for said resting piers. A method as claimed in claim 6, characterized in that said step (d) provides shifting of the trencher means (20) a minimum distance so as to form a continuous inverted arch (18) or resting pier structure. A method as claimed in claim 6, characterized in that said step (d) provides shifting of the trencher means (20) an appropriate distance so as to form a discrete inverted arch (18) or resting pier structure. A method as claimed in claim 6, characterized in that said step (c) provides transverse translation substantially from one side to the other of the tunnel. A method as claimed in claim 6, characterized in that said step (c) comprises the further steps of: c1) translating transversely across part of the tunnel, forming a first base half-trench; c2) casting concrete in said half-trench so as to form a half grade beam; c3) translating transversely across the remainder of the tunnel, completing the base trench; and c4) casting concrete to complete the grade beam.

Inventors: TREVISANI DAVIDE, TREVISANI, DAVIDE
Applicants: TREVI SPA, TREVI S.P.A.
Application year: 1996
Main classification: E21D9
IPC codes: E21D9