Tunnel excavation method

Abstract

To surely reinforce the ground in front of a tunnel face, eliminate the need to cut off a face reinforcing pipe, and minimize a generation of industrial waste.SOLUTION: A tunnel excavation method includes a first step of rotary-driving a face reinforcement pipe 1 from a first face 201a of a tunnel into the ground ahead by using a hollow, tubular face reinforcement pipe 1 having a twisted ridge 12 formed on its outer periphery over almost its entire length, an annular drilling bit 2 at its front end, and a rotating jig 3 connected to a drilling machine 101 at its rear end, a second step of proceeding with the tunnel excavation from the first face 201a to a second face 201b without cutting the face reinforcement pipe 1, leaving a part of the face reinforcement pipe 1 exposed from the second face 201b, and a third step of rotary-driving the face reinforcement pipe 1 again into the ground ahead of the second face 201b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a tunnel excavation method for excavating a tunnel while reinforcing the natural ground in front of a mirror surface of an excavated tunnel space. [Background technology]

[0002] Conventionally, as a method for excavating a tunnel to reinforce the ground in front of the tunnel mirror surface and prevent the face from pushing out, the excavation methods of Patent Documents 1 and 2 are known. The excavation methods of Patent Documents 1 and 2 involve driving a long steel pipe into the ground in front of the tunnel mirror surface, injecting an anchoring material such as a chemical injection or grout through the long steel pipe into the ground around the long steel pipe, and anchoring the long steel pipe to the ground with the hardened anchoring material to reinforce the ground in front of the tunnel mirror surface and ensure safety during the tunnel excavation work.

[0003] Furthermore, Patent Document 3 discloses a tunnel excavation method for reinforcing the ground in front of the tunnel mirror surface without using an anchoring material, in which a hole is drilled from the tunnel mirror surface to the ground in front, a special-shaped pipe is inserted into the hole, and the concave portion plastically deforms into a convex shape and expands in diameter by increasing the pressure in the internal space, and the special-shaped pipe is expanded in diameter by pumping a fluid into the special-shaped pipe, thereby anchoring it to the ground (see claim 2 of Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-176238 A [Patent Document 2] JP 2014-37714 A [Patent Document 3] JP 2004-19359 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the tunnel excavation methods of Patent Documents 1 and 2, the long steel pipes with the anchoring material attached must be excavated together with the natural ground when the tunnel is excavated, which means that it is time-consuming to cut off the long steel pipes that are mirror reinforcement materials. Furthermore, the cut-off steel pipes with the anchoring material attached become industrial waste, which generates a large amount of industrial waste. In addition, the tunnel excavation method of Patent Document 3 also requires that the expanded deformed pipes, which are mirror reinforcement materials, be excavated together with the natural ground, which means that it is difficult to cut them and causes the same problems of time-consuming cutting and the generation of a large amount of industrial waste from the cut-off deformed pipe parts.

[0006] The present invention has been proposed in consideration of the above-mentioned problems, and aims to provide a tunnel excavation method that can reliably reinforce the ground in front of the tunnel mirror surface, eliminates the need to cut off the mirror reinforcing pipe, and minimizes the generation of industrial waste. [Means for solving the problem]

[0007] The tunnel excavation method of the present invention is characterized in that it uses a hollow, cylindrical mirror reinforcing tube having a twisted ridge formed on its outer periphery over almost its entire length, an annular drilling bit at its front end, and a rotating jig connected to a drilling machine at its rear end, and includes the following steps: a first step of rotary driving the mirror reinforcing tube from a first mirror surface of the tunnel into the ground in front of it; a second step of proceeding with the excavation of the tunnel from the first mirror surface to the second mirror surface without cutting the mirror reinforcing tube, leaving a part of the mirror reinforcing tube exposed from the second mirror surface; a third step of rotary driving the mirror reinforcing tube again into the ground in front of the second mirror surface; and a fourth step of proceeding with the excavation of the tunnel from the second mirror surface to the third mirror surface without cutting the mirror reinforcing tube, leaving a part of the mirror reinforcing tube exposed from the third mirror surface. According to this, the mirror reinforcing tube is fixed to the natural ground by the frictional force between the twisted ribs over almost the entire length of the mirror reinforcing tube and the natural ground, and can resist the pushing force from the natural ground in front of the tunnel face. Furthermore, the sand and soil of the natural ground enters the hollow mirror reinforcing tube in a consolidated state from the annular drilling bit, and the consolidated sand and soil that enters the mirror reinforcing tube also exerts a natural ground reinforcing effect. Therefore, the natural ground in front of the tunnel mirror surface can be reliably reinforced. In addition, since the mirror reinforcing tube is not cut off and is again rotated and cast, the labor of cutting off the mirror reinforcing tube is eliminated and the generation of industrial waste can be suppressed as much as possible. In addition, by forming the ribs on the outer periphery of the mirror reinforcing tube into the shape of a twisted rib, the mirror reinforcing tube can be rotated and cast smoothly without performing another drilling using a drilling rod with a drilling bit. In addition, since the natural ground in front of the tunnel mirror surface can be reinforced without using an anchoring material, the process of injecting an anchoring material is eliminated and the tunnel excavation construction process can be made more efficient.

[0008] The tunnel excavation method of the present invention is characterized in that, in the first step, the mirror reinforcing tube is rotary-driven from the first mirror surface to the ground in front of it so that the rear end of the mirror reinforcing tube is exposed from the first mirror surface, and in the third step, the mirror reinforcing tube is again rotary-driven into the ground in front of the second mirror surface so that the rear end of the mirror reinforcing tube is exposed from the second mirror surface. This makes it possible to reliably reinforce the ground up to the ground adjacent to the tunnel mirror surface, ensuring the safety of tunnel excavation work even in conditions where the ground is loose.

[0009] The tunnel excavation method of the present invention is characterized in that, in the first step, the mirror reinforcing pipe is rotary-driven from the first mirror surface to the ground in front of it so that the entirety of the mirror reinforcing pipe is embedded further back than the first mirror surface, and in the third step, the mirror reinforcing pipe is again rotary-driven into the ground in front of the second mirror surface so that the entirety of the mirror reinforcing pipe is embedded further back than the second mirror surface. According to this, when tunnel excavation proceeds to the next mirror surface without cutting off the mirror reinforcing pipe, it is possible to minimize the interference of the mirror reinforcing pipe driven into the ground ahead with the excavation work.

[0010] The tunnel excavation method of the present invention is characterized in that the rotating jig is provided with an engagement groove capable of engaging with the torsional protrusion, and the rotating jig is attached to the rear end side of the mirror reinforcement tube by engaging the torsional protrusion with the engagement groove. With this, the twisted protrusion of the mirror reinforcing tube can be engaged with the engaging groove of the rotating jig, allowing the rotating jig to be easily attached to the rear end of the mirror reinforcing tube and removed, thereby making construction more efficient. Effect of the Invention

[0011] According to the tunnel excavation method of the present invention, the ground in front of the tunnel mirror surface can be reliably reinforced, the labor required to cut off the mirror reinforcing pipe is eliminated, and the generation of industrial waste can be minimized. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is an explanatory perspective view of a mirror reinforcing pipe used in an embodiment of the tunnel excavation method according to the present invention. [Diagram 2] FIG. 2 is an explanatory oblique view illustrating rotary casting of a mirror reinforcement pipe by a boring machine in a tunnel excavation method according to an embodiment. [Diagram 3] 3(a) to 3(c) are schematic process diagrams illustrating a tunnel excavation method according to a first example of the embodiment. [Figure 4] FIG. 4 is a half-cut cross-sectional perspective view of a mirror reinforcement pipe in a cast state in an embodiment. [Diagram 5] 5(a) to 5(c) are schematic process diagrams illustrating a tunnel excavation method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Tunnel excavation method according to an embodiment] A tunnel excavation method according to an embodiment of the present invention is carried out using a hollow cylindrical head reinforcing pipe 1 shown in Fig. 1, and a twisted ridge 12 is formed on the outer periphery of the head reinforcing pipe 1, protruding outward over substantially the entire length. The twisted ridge 12 in this embodiment is composed of a helical ridge formed in series over the entire axial length of the base tube 11 by hot extrusion, punching or the like during the manufacture of the steel pipe, and in the illustrated example, four helical ridges are formed at substantially equal intervals over the entire length of the smooth outer circumferential surface of the base tube 11.

[0014] 1, an annular drilling bit 2 is provided at the front end of the mirror reinforcing tube 1. The drilling bit 2 has a face tip provided at the front end of the base ring 21, drilling blades 22 formed at approximately spaced intervals around the outer periphery, and openings 23 communicating in the axial direction. The drilling bit 2 is provided integrally with the mirror reinforcing tube 1 by, for example, fixing it to the front end of the base tube 11 of the mirror reinforcing tube 1 by welding, but it may also be possible to form an engagement portion near either the front end of the base tube 11 or the rear end of the base ring 21 and an engagement recess on the other, and attach the drilling bit to the front end of the mirror reinforcing tube 1 by engaging the engagement portion with the engagement recess, or to attach the drilling bit by screw connection.

[0015] A rotating jig 3 connected to a drilling machine 101 is attached to the rear end of the mirror reinforcing tube 1 (see Figures 1 and 2). The bottomed, cylindrical front portion 31 of the rotating jig 3 is provided with an engagement groove 32 cut out from the front end and extending along the axial direction, or an engagement groove 32 cut out from the front end and extending at an angle to the axial direction, so that the torsional ridge 12 of the mirror reinforcing tube 1 engages with the engagement groove 32, allowing the rotating jig 3 to be detachably attached to the rear end of the mirror reinforcing tube 1.

[0016] The rotating jig 3 is provided with a generally cylindrical rear portion 33 having a smaller diameter than the front portion 31. The rear portion 33 of the rotating jig 3 is adapted to be detachably engaged and connected to, for example, a drilling rod 102 of a drilling machine 101, and this engagement is achieved by the forward rotation of the drilling rod 102 of the drilling machine 101, and is released from the engagement by the reverse rotation.

[0017] 2, a drilling machine 101 for rotary driving the head reinforcement pipe 1 is provided on a guide cell 103 attached to the arm of, for example, a drill jumbo, and is mounted on the guide cell 103 so as to be able to move forward and backward freely. The head reinforcement pipe 1 connected to the drilling rod 102 or the drilling machine 101 via a rotating jig 3 connected to the drilling rod 102 is rotary driven into the natural ground 200 of the tunnel from the head surface 201.

[0018] When a tunnel is excavated using the mirror reinforcing pipe 1, for example as shown in Fig. 3(a), the mirror reinforcing pipe 1 with a drilling bit 2 attached to its front end and a rotating jig 3 connected to a drilling machine 101 attached to its rear end is rotary cast into the natural ground 200 ahead from a first mirror surface 201a of a tunnel space T provided with shoring 202 and sprayed concrete 203 so as to form a drilling hole 204. The mirror reinforcing pipe 1 is usually cast into a plurality of places on the first mirror surface 201a, each in the direction of tunnel excavation.

[0019] 3, each mirror reinforcing pipe 1 is rotationally cast from the first mirror surface 201a into the natural ground 200 in front of it, with the rear end of each mirror reinforcing pipe 1 exposed from the first mirror surface 201a to the tunnel space T. The length of the mirror reinforcing pipe 1 to be cast may be any length within the scope of the present invention, but it is preferable to use a length of about 3m to 6m, such as a length of about 4.5m that can suppress the pushing force F of the natural ground 200 from the mirror surface 201 to about 4.5m and ensure reliable rotational casting.

[0020] By rotary casting the mirror reinforcing pipe 1 into the ground 200 from the first mirror surface 201a, as shown in Figure 4, the soil 205 of the ground 200 enters in a compressed state from the opening 23 of the annular drilling bit 2 into the inside of the base tube 11 of the mirror reinforcing pipe 1, and as a result, the compressed soil 205 also becomes part of the mirror reinforcing pipe 1, stabilizing the ground 200 in front of the mirror surface 201 and suppressing the force that pushes the ground toward the tunnel space.

[0021] After the casting of the mirror reinforcing pipes 1 on the first mirror surface 201a is completed, as shown in Fig. 3(b), the tunnel is excavated from the first mirror surface 201a to the second mirror surface 201b without cutting off each mirror reinforcing pipe 1, so that a part of each mirror reinforcing pipe 1 is exposed from the second mirror surface 201b. That is, in the tunnel excavation progress from the first mirror surface 201a to the second mirror surface 201b in the tunnel excavation method of the first embodiment, the natural ground 200 is excavated from the first mirror surface 201a to the second mirror surface 201b, for example, by digging a distance of about 1m so that the length of each mirror reinforcing pipe 1 cast in the natural ground 200 exposed to the tunnel space T becomes long. In addition, a support 202 is erected corresponding to the area between the first mirror surface 201a and the second mirror surface 201b, and a shotcrete 203 is cast.

[0022] After the tunnel excavation has progressed to the second mirror surface 201b, as shown in Fig. 3(c), the mirror reinforcing pipes 1 are again rotary-cast into the natural ground 200 in front of the second mirror surface 201b, and each mirror reinforcing pipe 1 is cast from the second mirror surface 201b toward the natural ground 200 on the deeper side. At this time, in the first embodiment, the mirror reinforcing pipes 1 are again rotary-cast into the natural ground 200 in front of the second mirror surface 201b, for example, about 1 m, so that the vicinity of the rear end of the mirror reinforcing pipe 1 is exposed from the second mirror surface 201b, in other words, the length of each mirror reinforcing pipe 1 cast into the natural ground 200 exposed from the second mirror surface 201b to the tunnel space T is shortened. Furthermore, even when the mirror reinforcing pipe 1 is rotated and cast again from the second mirror surface 201b, the state in which the soil 205 of the ground 200 has entered in a compressed state into the inside of the base tube 11 of the mirror reinforcing pipe 1 through the opening 23 of the annular drilling bit 2 is maintained (see Figure 4).

[0023] 3(b), tunnel excavation proceeds from the second mirror surface 201b to the third mirror surface 201c without removing each mirror reinforcing tube 1, leaving a portion of each mirror reinforcing tube 1 exposed from the third mirror surface 201c. Thereafter, the steps of FIG. 3(c), FIG. 3(b), and FIG. 3(c) are repeated to proceed with tunnel excavation.

[0024] As another tunnel excavation method using the mirror reinforcing pipe 1, a tunnel may be excavated as in the second embodiment of Fig. 5. In the second embodiment, when the mirror reinforcing pipe 1, which has a drill bit 2 provided at its front end and a rotary jig 3 connected to a drilling machine 101 attached at its rear end, is rotary-driven from the first mirror surface 201a to the natural ground 200 in front so as to form a drill hole 204, the mirror reinforcing pipe 1 is rotary-driven from the first mirror surface 201a to the natural ground 200 in front so that the entire mirror reinforcing pipe 1 is embedded in the natural ground 200 behind the first mirror surface 201a (see Fig. 5(a)).

[0025] In the second embodiment as well, by rotary driving the head reinforcement pipe 1 into the natural ground 200 from the first head surface 201a, the soil 205 of the natural ground 200 enters in a consolidated state from the opening 23 of the annular drill bit 2 into the inside of the base tube 11 of the head reinforcement pipe 1 (see FIG. 4). The length of the head reinforcement pipe 1 used in the second embodiment should be the same as that used in the first embodiment.

[0026] After the casting of the mirror reinforcing pipes 1 on the first mirror surface 201a is completed, as shown in Fig. 5(b), the tunnel is excavated from the first mirror surface 201a to the second mirror surface 201b without removing each of the cast mirror reinforcing pipes 1, so that a part of each mirror reinforcing pipe 1 is exposed from the second mirror surface 201b. That is, in the tunnel excavation progress from the first mirror surface 201a to the second mirror surface 201b in the tunnel excavation method of the second embodiment, the natural ground 200 is excavated from the first mirror surface 201a to the second mirror surface 201b, for example, by digging a distance of about 1m, so that a part near the rear end of each mirror reinforcing pipe 1, which is entirely buried in the natural ground 200, is exposed from the second mirror surface 201b to the tunnel space T. Further, a support 202 is erected between the first mirror surface 201a and the second mirror surface 201b, and sprayed concrete 203 is poured.

[0027] After the tunnel excavation has progressed to the second mirror surface 201b, as shown in FIG. 5(c), the mirror reinforcing pipe 1 is again rotary-cast into the natural ground 200 in front of the second mirror surface 201b, and each mirror reinforcing pipe 1 is cast from the second mirror surface 201b toward the natural ground 200 on the far side. At this time, in the second embodiment, the mirror reinforcing pipe 1 is again rotary-cast into the natural ground 200 in front of the second mirror surface 201b, for example, about 1 m, so that the entire mirror reinforcing pipe 1 is embedded in the natural ground 200 on the far side of the second mirror surface 201b. Even when the mirror reinforcing pipe 1 is again rotary-cast from the second mirror surface 201b, the state in which the soil 205 of the natural ground 200 has entered in a consolidated state into the inside of the base tube 11 of the mirror reinforcing pipe 1 from the opening 23 of the annular drill bit 2 is maintained (see FIG. 4).

[0028] 5(b), tunnel excavation proceeds from the second mirror surface 201b to the third mirror surface 201c without removing each mirror reinforcing tube 1, leaving a portion of each mirror reinforcing tube 1 exposed from the third mirror surface 201c. Thereafter, the steps of FIG. 5(c), FIG. 5(b), and FIG. 5(c) are repeated to proceed with tunnel excavation.

[0029] According to the tunnel excavation method of this embodiment, the frictional force between the torsional ridge 12 over almost the entire length of the tunnel reinforcement pipe 1 and the natural ground 200 allows the tunnel reinforcement pipe 1 to be fixed to the natural ground 200, and to resist the pushing force F from the natural ground 200 in front of the tunnel face. Furthermore, sand and soil from the natural ground 200 enters the hollow tunnel reinforcement pipe 1 in a consolidated state from the annular drill bit 2, and the consolidated sand and soil that has entered the tunnel reinforcement pipe 1 also exerts a natural ground reinforcing effect as part of the tunnel reinforcement pipe 1. Therefore, the natural ground 200 in front of the tunnel mirror surface 201 can be reliably reinforced.

[0030] In addition, since this is a construction method in which the mirror reinforcing pipe 1 is rotated and cast again without cutting it off, the effort of cutting the mirror reinforcing pipe 1 is eliminated, and the generation of industrial waste can be minimized. Furthermore, by forming the protrusions on the outer periphery of the mirror reinforcing pipe 1 into the shape of twisted protrusions 12, the mirror reinforcing pipe 1 can be smoothly rotated and cast in place without the need for separate drilling using a drilling rod with a drill bit. Furthermore, since the natural ground 200 in front of the tunnel mirror surface 103 can be reinforced without using an anchoring material, the process of injecting an anchoring material is eliminated, and the tunnel excavation construction process can be made more efficient.

[0031] In addition, by providing the rotating jig 3 with an engagement groove 32 capable of engaging with the twisted protrusion 12 of the mirror reinforcing tube 1, the twisted protrusion 12 of the mirror reinforcing tube 1 can be engaged with the engagement groove 32 of the rotating jig 3, allowing the rotating jig 3 to be easily attached and removed to the rear end of the mirror reinforcing tube 1, thereby making construction more efficient.

[0032] Furthermore, according to the tunnel excavation method of the first embodiment, by excavating the tunnel while constantly exposing the mirror reinforcing tube 1 from the mirror surface 201, it is possible to reliably reinforce the ground 200 in front of the tunnel mirror surface 201 up to the ground 200 adjacent to the tunnel mirror surface 201, thereby ensuring the safety of the tunnel excavation work even when the ground 200 is loose.

[0033] Furthermore, according to the tunnel excavation method of the second embodiment, by intermittently embedding the mirror reinforcing pipe 1 into the back side of the mirror surface 201 while excavating the tunnel, it is possible to minimize the interference of the mirror reinforcing pipe 1 driven into the ground 200 ahead with the excavation work when proceeding with tunnel excavation to the next mirror surface 201 without removing the mirror reinforcing pipe 1.

[0034] [Scope of the invention disclosed herein] The invention disclosed in this specification includes, in addition to each invention, embodiment, and example listed as the invention, those specified by changing partial contents of these to other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial action and effect can be obtained, and specifying them as a higher conceptualization. The invention disclosed in this specification also includes the following contents and further modified examples described below.

[0035] For example, in the above embodiment, the twisted ribs formed on the outer periphery of the head reinforcing tube in the present invention over almost the entire length are helical ribs formed continuously over the entire length of the smooth outer periphery of the base tube 11 by hot extrusion, punching or the like during the manufacture of the steel tube, but the present invention is not limited to this, and it is also suitable to use a head reinforcing tube in which helical ribs corresponding to the twisted ribs and helical grooves between the helical ribs are formed continuously over the entire length of the head reinforcing tube, such as a steel tube formed by twisting a steel tube with ribs extending in the axial direction, or a tube formed by welding with helical ribs. Also, if the necessary frictional force with the ground can be obtained, it is also possible to use twisted ribs formed intermittently scattered over almost the entire length of the outer periphery of the head reinforcing tube. [Industrial Applicability]

[0036] The present invention can be used when excavating a tunnel while reinforcing the ground in front of the mirror surface of the excavated tunnel space. [Explanation of symbols]

[0037] 1...Mirror reinforcing tube 11...Base tube 12...Twisted ridge 2...Drilling bit 21...Base ring 22...Drilling blade 23...Opening 3...Rotating jig 31...Front 32...Engagement groove 33...Rear 101...Drilling machine 102...Drilling rod 103...Guide cell 200...Natural ground 201, 201a, 201b, 201c...Mirror surface 202...Support 203...Sprayed concrete 204...Drilling 205...Soil T...Tunnel space F...Extrusion force of natural ground

Claims

1. a first step of rotary driving a hollow cylindrical mirror reinforcing tube having a twisted ridge formed on its outer periphery over substantially its entire length, a ring-shaped drilling bit provided at its front end, and a rotary jig connected to a drilling machine attached at its rear end, from a first mirror surface of the tunnel into the natural ground in front of the tunnel; a second step of excavating the tunnel from the first mirror surface to the second mirror surface without cutting the mirror reinforcing tube, leaving a portion of the mirror reinforcing tube exposed from the second mirror surface; A third step of again rotating and driving the mirror reinforcing pipe into the ground in front of the second mirror surface; and a fourth step of continuing excavation of the tunnel from the second mirror surface to the third mirror surface without cutting off the mirror reinforcing tube, leaving a portion of the mirror reinforcing tube exposed from the third mirror surface.

2. In the first step, the mirror reinforcing pipe is rotated and driven from the first mirror surface to the front ground so that the rear end of the mirror reinforcing pipe is exposed from the first mirror surface, A tunnel excavation method as described in claim 1, characterized in that in the third step, the mirror reinforcing pipe is again rotary-cast into the ground in front of the second mirror surface so that the rear end of the mirror reinforcing pipe is exposed from the second mirror surface.

3. In the first step, the mirror reinforcing pipe is rotary driven from the first mirror surface to the front ground so that the entire mirror reinforcing pipe is embedded behind the first mirror surface, A tunnel excavation method as described in claim 1, characterized in that in the third step, the mirror reinforcing tube is re-rotated and cast into the ground in front of the second mirror surface so that the entire mirror reinforcing tube is embedded behind the second mirror surface.

4. The rotating jig is provided with an engagement groove that can engage with the twisted protrusion, A tunnel excavation method according to any one of claims 1 to 3, characterized in that the rotating jig is attached to the rear end side of the mirror reinforcement tube by engaging the torsional protrusion with the engaging groove.

Images