METHOD OF BUILDING UNDERGROUND CAVERN AND TUNNELLING MACHINE

Abstract: A method of forming an underground passage, developed so as to safely and economically form a large-scale underground passage of a large depth in the soft ground or a soft rock layer, and a tunnel excavator suitably used in this method. This method of forming underground passages consists of the steps of forming a reinforced ground zone (A) around the portion of the ground in which a large-scale passage is to be excavated, before starting the excavation, and then excarting the inner side of this reinforced ground zone. A tunnel excavator (4) is provided with a ring-shaped body having first, second and third rings (20, 21, 22); boring units (41-43) provided between the second ring (21) and a propulsive jack (25) and adapted to make a plurality of radial bores (60) in the inner surface of a tunnel; and reinforcing material fillers (48-52) provided also between the second ring and propulsive jack and adapted to fill these bores with a reinforcing material (53).

Description: TECHNICAL FIELD OF THE INVENTION This invention relates to a method of forming an underground cavern, and more particularly, to a method of building an underground cavern of a large scale at a very deep place, and a tunneling machine suitable for use in a part of the process of building an underground cavern. BACKGROUND ART OF THE INVENTION Underground caverns of a large scale built at very deep places of the kind mentioned above are extremely big caverns having a depth of about 100 meters and inside dimensions of about 100 meters, and are utilized for underground power stations and natural resources storing depots, etc. Such underground caverns are generally built in hard rock beds. However, with the development of high-degree utilization of underground space of late years, there are strong demands for building such caverns of a large scale at very deep places in soft grounds even in urban communities. German article "Bauverfahren für das Auffahren sehr großer untertägiger Räume (methods of construction for the excavation of very large caverns)", published in Baumaschine und Bautechnik. BMT, volume 29, no. 6 June 1982, pages 302-307, Wiesbaden, Germany discloses a method for excavation of very large caverns which comprises a step of digging a spiral-formed tunnel encompassing the cavern to be hollowed out and drilling holes into the portions of the wall of the tunnel corresponding to the cavern to be excavated, and inserting reinforcing means, i.e. anchor balls into the holes. This method is disadvantageous in so far as the curved tunnel prevents the use of heavy and long equipment and in that the fact that only one tunnel is used prevents the use of multiple equipment in order to accelerate the whole procedure of digging the tunnel. It is therefore an object of the present invention to provide a method for reinforcing the outer sphere of a cavern to be excavated by digging a tunnel and using the walls of said tunnel to insert reinforcing means, which can be carried out faster and more efficiently using heavy equipment. German patent application DE-A-1 945 400 furthermore discloses a tunneling machine which is equipped with an optional add-on boring device, said boring device being aligned in a direction perpendicular to the ground surface. Said boring device is used for drilling a well. It is a further object of the present invention to provide a tunneling machine which can be used for the additional purpose to reinforce the walls of the tunnel simultaneously with the procedure of digging the tunnel, at least in the portions of the walls of said tunnel corresponding to said cavern to be excavated. The method related object is according to the invention solved by the features of the characterizing portion of claim 1. The solution of the machine related object according to the invention is characterized by the characterizing portion of claim 2. Further advantageous embodiments of the invention are set out in claims 3-10. According to one aspect of the present invention, there is provided a method of building an underground cavern, wherein the ground reinforcing zone forming step further comprises the steps of forming a ground reinforcing zone around a portion intended to be hollowed out; digging down a plurality of vertical tunnels extending from the ground surface over the whole ground reinforcing zone; digging out a plurality of holes by a ground reinforcing unit mounted on the tunneling machine from the inner surfaces of the portions of the vertical tunnels corresponding to the ground reinforcing zone in radial and random directions and at regular intervals in the longitudinal direction of the tunnels; and driving a glass fibre and then injecting a grout by the ground reinforcing unit into each of the holes thus formed, thereby forming reinforced portions within the predetermined ground reinforcing zone concurrently with the digging operations of the vertical tunnels. To achieve the above-mentioned further object, according to one aspect of the present invention, there is provided a tunneling machine having a cutter drum mounted on the leading end side of a ring-shaped machine body having an articulated construction and adapted, when it is rotated, to excavate earth and sand and send the spoil into the internal part of the machine body, and propelling jacks mounted on the rear part of the machine body, the tunneling machine further comprising a boring device mounted between the ring-shaped body and the propelling jacks for boring a plurality of holes extending substantially radially from the inner surface of a tunnel to be built, wherein the boring device is mounted on an annular turning frame which consists essentially of an annular frame supported rotatably through bearings on the inner surface of a ring forming part of said ring-shaped machine body so as to be moved in directions at right angles to the axis of said ring-shaped machine body. The ring-shaped body of said tunneling machine, advantageous comprises a first ring having a small diameter portion formed in the rear part thereof; a second ring having a small diameter portion formed in the rear part thereof and also having a large diameter front portion in which the small diameter rear portion of the first ring is loosely fitted through the intermediary of a sealing member; and a third ring having an annular frame which is open in the rear end portion thereof for molding a lining material and having a large diameter front portion in which the small diameter rear portion of the second ring is loosely fitted through the intermediary of a sealing member, and is characterized in that the first ring is concentrically interconnected with the second ring by a plurality of steering jacks mounted on the inner peripheries of the rings, and the second ring is concentrically interconnected with the third ring by a plurality of propelling jacks mounted on the inner peripheries of the rings. The above-mentioned boring device comprises a turning frame which consists of an annular frame supported rotatably through bearings on the inner surface of the second ring, and a girder frame fixedly secured on the inner surface of the annular frame; and a rotary striking type borer mounted on one side of the girder frame of the turning frame in such a manner that it may be moved in the directions at right angles to the axis of the second ring, and the above-mentioned ground reinforcing unit comprises a glass fibre reel mounted on the other side of the girder frame; a glass fibre feeding means mounted adjacent to the glass fibre reel for feeding a glass fibre supplied by the reel in turn into each of a plurality of holes bored by the boring device; a grout material storage tank which is located on the girder frame and to which a grout injection means is connected; and a reinforcing material supply unit mounted on the inner surface of the annular frame opposite to the glass fibre feeding means for supplying a glass fibre and a grout in turn into each of the holes bored in the ground. According to the method of building an underground cavern according to the present invention incorporating the above-mentioned aspects, an underground cavern of a large scale can be built safely and economically in a soft ground or in a soft rock bed at a very deep place. Further, by using the tunneling machine according to the present invention incorporating the above-mentioned aspects, a reinforcing zone can be formed efficiently around a cavern to be built prior to excavating the latter. The above-mentioned and other objects, aspects and advantages of the present invention will become apparent to those skilled in the art by making reference to the following description and the accompanying drawings in which preferred embodiments incorporating the principles of the present invention are shown by way of example only. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory view showing a prior art method of building an underground cavern, Fig. 2 is an explanatory view showing the method according to the present invention; Fig. 3 is a fragmentary sectional view showing another embodiment of the reinforcing portion which is formed by the method of the present invention; Fig. 4 is a schematic explanatory view showing three examples of caverns having different shapes; Fig. 5 is a schematic, overall side elevational view of a tunneling machine used to carry out the method of the present invention; Fig. 6 is a longitudinal sectional view of principal parts of the tunneling machine shown in Fig. 11; Fig. 7 is a cross-sectional view of the principal parts of the tunneling machine; and Fig. 8 is a sectional view of principal parts of a boring device for use in the tunneling machine. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will now be described below by way of several embodiments with reference to Figs. 2 to Fig. 8. At first, however, reference is made to Fig. 1 illustrating a prior art method of building an underground cavern, wherein the tunneling machine 4 is lowered to the starting station 5 and then started therefrom so as to move forwards in the above-mentioned ground reinforcing zone 2 to thereby dig out a spirally extending tunnel around a portion 1 intended to be hollowed out later. To form a ground reinforcing portion A in the above-mentioned predetermined reinforcing zone 2 concurrently with the digging operation, a plurality of holes are digged out by a ground reinforcing unit 7 mounted on the tunneling machine 4 from the inner surface of the tunnel 6 in radial and random directions and at regular intervals in the longitudinal direction of the tunnel 6, and a glass fibre is driven and then a grout is injected by the ground reinforcing unit in turn into each of the holes thus formed, thereby forming a plurality of pairs of reinforcing arms 8 along the tunnel 6. In this case, the spacing between the vertically adjacent rows of the spirally extending tunnel 6 is set such that the reinforcing arms 8 of the vertically adjacent rows may overlap with each other. Further, the spirally extending tunnel 6 is not to be limited only to one length, as shown, a plurality of lengths of independent tunnels 6 may be provided by using a plurality of tunneling machines 4. By effecting the above-mentioned operation, the ground reinforcing portion A can be formed around the portion 1 to be hollowed out to form the cavern. Fig. 2 shows an embodiment of the method of the present invention. In this embodiment, a plurality of vertical tunnels 14 are formed so as to extend downwards from the ground surface, and at the same time, a ground reinforcing portion A″ surrounding a portion 17 to be hollowed out is formed by a plurality of pairs of reinforcing arms 8, each pair of which is formed by digging a plurality of holes from the inner surfaces of the vertical tunnels 14 corresponding to the predetermined ground reinforcing zone in radial and random directions and at regular intervals along the tunnels, and driving a glass fibre and then injecting a grout into each of the holes. After that, the portion 17 to be hollowed out is excavated to form a cavern B″. Fig. 3 shows an embodiment of the configuration of a reinforcing portion in the ground reinforcing zone A ∿ A″ wherein reinforcing arms 8 are directed to the outside of the caverns B ∿ B″. The shapes of the above-mentioned caverns B ∿ B″ include a spherical shape, a semicylindrical shape, and a rectangular parallelpiped, etc., as shown in Fig. 4. Whilst, in the above-mentioned embodiments, the reinforcing zones A ∿ A″ are shown as being formed by glass fibers and grout, such reinforcing zones may be formed by reinforcing means such as insertion of lock bolts, injection of a chemical, or freezing, etc. In the next place, an embodiment of the tunneling machine 4 suitable for use in carrying out the method of the present invention will be described with reference to Figs. 5 to 8. In the drawings, reference numeral 20 denotes a first ring, 21 a second ring, and 22 a third ring, all of which are of a cylindrical shape. The rear portion of each of the first and second rings 20 and 21 is smaller in diameter than each of their respective front portions. The small diameter rear portion of the first ring 20 is loosely fitted in the large diameter front portion of the second ring 21 through the intermediary of a sealing member 23a. Whilst, the small diameter rear portion of the second ring 21 is loosely fitted in the large diameter front portion of the third ring 22 through the intermediary of a sealing member 23b. The first ring 20 is concentrically connected to the second ring 21 by means of steering jacks 24, whilst the second ring 21 is concentrically connected to the third ring 22 by means of propelling jacks 25. A plurality of jacks 24 and a plurality of jacks 25, respectively are mounted circumferentially of the rings. The third ring 22 has an annular frame 26 formed in the rear part thereof, and which is open rearwardly for molding a lining material. A lining material injection pipe 27 is connected to the annular frame 26. Reference numeral 28 denotes a cutter drum mounted in front of the first ring 20. This cutter drum 28 has a support shaft 29 which is supported together with a reduction gear 31a and motors 31 by a shaft support wall 30 mounted within the first ring 20. The cutter drum 28 is arranged to be rotated through the support shaft 29 by the motors 31. The cutter drum 28 has disk cutters 28a mounted thereon and an earth and sand or spoil intake (not shown) formed therein. The arrangement is made such that when the cutter drum 28 is rotated the earth and sand in front thereof is excavated and the spoil is taken through the spoil intake into a chamber 32 defined between the support wall 30 of the first ring 20 and the cutter drum 28. A mud supply pipe 33 and a mud discharge pipe 34 extend into this chamber 32. Further, an agitator 36 connected to a motor 35 is mounted in the chamber 32. The portion of the above-mentioned second ring 21 is the ground reinforcing unit 7 mounted on the tunneling machine 4 which is already mentioned in the description of the method of forming an underground cavern. The configuration of the ground reinforcing unit 7 will be described below with reference to Figs. 6, 7 and 8. A turning frame 37 is rotatably supported concentrically with the second ring 21 and within the latter. This turning frame 37 is comprised of an annular frame 39 supported rotatably by bearings 38, 38 on the inner surface of the second ring 21, and a girder frame 40 fixedly secured to the inner surface of the annular frame 39. A rotary striking type boring device 41 is mounted on one side of the girder frame 40 in such a manner that it may be moved at right angles to the axis of the second ring 21, and is threadably engaged with a feed screw 42. Reference numeral 43 denotes a feed motor. As is apparent from Fig. 8, the portion of the annular frame 39 opposite to the axis of the above-mentioned rotary striking type boring device 41 has a hole 45 formed therein and through which a boring rod 44 is passed. The hole 45 has sealing members 46 attached to the inner surface thereof. The girder frame 40 is provided with a rod receiver 47 accommodating boring rods 44 for connection purposes. Further, the girder frame 40 is provided with a glass fibre reel 48, a glass fibre feeding means 49, a grout material storage tank 50, and a grout injection means 51. The leading ends of the glass fibre feeding means 49 and the grout injection means 51 are connected to a reinforcing material supply unit 52. This reinforcing material supply unit 52 includes a sealing member applied to the inner surface of the second ring 21, and a cutter member for cutting a glass fibre 53, and both of the sealing member and the cutter member are not shown. Further, this reinforcing material supply unit 52 and the hole 45 through which the above-mentioned boring rod 44 is passed are located in one and the same plane perpendicular to the axis of the second ring 21. The above-mentioned second ring 21 has holes 54 formed at a plurality of places along the circumference thereof and in a plane containing the hole 45 of the turning frame 37 through which the boring rod 44 is passed, and the reinforcing material supply unit 52. The annular frame 39 of the tuning frame 37 has a ring gear 55 mounted thereon and which meshes with a drive gear 57 connected to the turning motor 56. The operation of the tunneling machine 4 constructed as mentioned above will be described below. By rotating the cutter drum 28 while the tunneling machine 4 is pushed ahead by the propelling jacks 25, the tunneling machine 4 is moved forwards while it is digging out a tunnel end face to form a tunnel 6. The earth and sand excavated at that time or the spoil is taken once into a chamber 34 from where the spoil is discharged rearwards through the mud discharge pipe 34. The inner surface of the tunnel 6 thus formed by excavation is lined with a lining material injected onto the inner surface thereof, with the aid of the annular frame 26 mounted on the rear end portion of the third ring 22. This lining material is of the property which becomes hard in a short time, and the tunneling machine 4 is propelled using the hardened lining as a foothold. Steering of the tunneling machine 4 is made by changing the angle of excavation between the first ring 20 and the second ring 21 by the action of the steering jacks 24. In the next place, operation of reinforcing the inner wall of the tunnel with a reinforcing material while the tunnel is being digged out by the above-mentioned tunneling machine 4 takes place. First of all, the propulsion of the tunneling machine 4 by the propelling jacks 25 is stopped. (Even if the steering jacks 24 and the cutter drum 28 are then operating, it does not matter.) Whilst, a boring rod 44 having a bit 59 fixedly secured to the leading end thereof is connected to a drive shaft of the rotary striking type boring device 41 by means of joints 58. In the next place, the turning frame 37 is turned by the turning motor 56 so as to locate the bit 59 opposite to the hole 54 formed in the second ring 21, and in this condition the rotary striking type boring device 41 is advanced by the feed screw 42 thereby advancing the boring rod 44 into the ground. As a result, a hole 60 is bored in the ground. The depth of the hole 60 can be adjusted to a value as required by connecting a plurality of the above-mentioned boring rods 44 by means of the joints 58 successively and in series. By turning the turning frame 37 successively, a multiplicity of holes 60 can be bored in consecutive order in the tunnel wall around the second ring 21. Subsequently, the reinforcing material supply unit 52 is located opposite to each of the holes 60 formed as mentioned above in consecutive order, and then glass fibre 53 is inserted into each of the holes 60 and then a grout material is injected into each of the holes 60 by the reinforcing material supply unit 52. The above-mentioned glass fibre 53 is fed from the glass fibre reel 48 through the glass fibre feeding means 49 into the reinforcing material supply unit 52, and then a grout material is injected by the grout injection means 51 into the reinforcing material supply unit 52. Thus, the tunnel 6 around the second ring 21 forming a portion of the ground reinforcing unit 7 is formed with a multiplicity of radially extending reinforcing arms 8, each being comprised of the glass fibre 53 and the grout. By conducting the above-mentioned operation each time the tunneling machine 4 has digged out the ground over a predetermined distance, the above-mentioned radially extending reinforcing arms 8 can be formed at regular intervals over the overall length of the tunnel 6, so that the extent of reinforcement by the reinforcing arms 8 will become any one of reinforcing zones A, A′ and A″. Further, whilst the above-mentioned embodiments show examples wherein the glass fibre 53 is used as the reinforcing material, a lock bolt may be used in place of the glass fibre. In that case, the lock bolt is inserted into the hole 60 by means of a feeding mechanism which is substantially the same as the above-mentioned boring device.

Claims: Method of building an underground cavern, comprising the steps of forming a ground reinforcing zone (A″) around a portion intended to be hollowed out prior to excavating the underground cavern to be formed (B″) and then excavating the interior of the ground reinforcing zone thereby forming the underground cavern, said ground reinforcing zone being provided by digging at least one tunnel extending from the ground surface through the ground reinforcing zone, drilling a plurality of holes extending from the inner surfaces of the portions of the tunnel corresponding to the ground reinforcing zone and inserting reinforcement means into the holes, characterized in that said step of digging a tunnel comprises digging down a plurality of vertical tunnels (14) extending from the ground surface over the whole ground reinforcing zone (A″), and drilling a plurality of holes (60) from the inner surfaces of only the portions of the vertical tunnels corresponding to the ground reinforcing zone in radial and random directions and at regular intervals in the longitudinal direction of the tunnels, driving a glass fiber and then injecting a grout into each of the holes thus formed, thereby forming reinforced portions within said predetermined ground reinforcing zone simultaneously with the digging of the vertical tunnels. Tunneling machine comprising: a cutter drum mounted on a leading end side of a ring-shaped machine body having an articulated construction and adapted, when it is rotated, to excavate earth and send the spoil into the internal part of the machine body, propelling jacks mounted on the rear part of the machine body, and a boring device mounted between the ring-shaped body and the propelling jacks for boring a plurality of holes extending substantially radially from the inner surface of the tunnel to be built, characterized in that the boring device (41) is mounted on an turning frame (37) which consists essentially of an annular frame (39) supported rotatably through bearings (38,38) on the inner surface of a ring forming part of said ring-shaped machine body so as to be moved in directions at right angles to the axis of said ring-shaped machine body. Tunneling machine according to claim 2, characterized in that said boring device (41,44) is mounted on one side of a girder frame (40) being secured to said annular frame (39). Tunneling machine according to claim 3, characterized in that said boring device (41) is of the rotary striking type. Tunneling machine according to any one of the anteceding claims, characterized in that the tunneling machine further comprises a ground reinforcing unit having a reinforcing material filling means for filling reinforcing material into each of the holes being drilled by said boring device, said ground reinforcing unit being mounted on said turning frame in a direction of 180° opposite to the drilling direction of said boring unit so as to be moved in directions at right angles to the axis of said ring-shaped machine body. Tunneling machine according to claim 5, characterized in that said ground reinforcing unit comprises a glass fiber reel (48) mounted on said girder frame (40), a glass fiber feeding means (49) mounted adjacent to said glass fiber reel (48) for feeding a glass fiber supplied by the reel in turn into each of the holes (60) of said plurality of holes bored by the boring device. Tunneling machine according to claim 6, characterized in that a grout material storage tank (50) is connected to a grout injection means (51) which is mounted on said girder frame. Tunneling machine according to claim 7, characterized in that said grout material storage tank (50) is mounted on said girder frame (40). Tunneling machine according to anyone of the anteceding claims characterized by reinforcing material supply unit (52) mounted on the inner surface of the annular frame (39) for supplying a glass fiber (53) and a grout into each of said holes (60) being drilled by the boring unit (41).

Inventors: FURUMI K C O THE INSTITUTE OF, NAKAMURA J C O THE INST OF K K, FURUMI, K. C/O THE INSTITUTE OF K.K.KOMATSU SEISA., NAKAMURA, J. C/O THE INST. OF K.K.KOMATSU SEISAKU.
Applicants: KOMATSU MFG CO LTD, KABUSHIKI KAISHA KOMATSU SEISAKUSHO
Application year: 1989
Main classification: E21D13
IPC codes: E21D9, E21D13