Pit mouth reinforcement structure and pit mouth reinforcement method of vertical pi formed using steep pipe

Abstract

To provide a pit mouth reinforcement structure and a pit mouth reinforcement method for a vertical pit formed using steel pipes, which allow the pit mouth to be structurally safely reinforced on as small a scale as possible, while ensuring sufficient space inside the pit after construction.SOLUTION: A pit mouth reinforcement structure 70 that reinforces a pit mouth 63 provided on a side wall of a vertical pit 60 formed using circular steel pipes 61 comprises: a pair of reinforcement columns 71 erected on the right and left sides of the pit mouth 63; a pair of reinforcement beams 72 joined to the pair of reinforcement columns 71 at an upper side and a lower side of the pit mouth 63; a plurality of first arcuate reinforcement ribs 74 attached, at intervals in a height direction, to an area opposite to the pit mouth 63 in a height range of the pit mouth 63; and a plurality of second annular reinforcement ribs 75 attached, at intervals in the height direction, to at least one of upper and lower areas of the pit mouth 63, wherein the second reinforcement ribs 75 are provided in an area corresponding to a converted diameter of the pit mouth 63 in at least one of the upper and lower areas of the pit mouth 63.SELECTED DRAWING: Figure 11B

Description

[Technical Field]

[0001] The present invention relates to a shaft opening reinforcing structure and a shaft opening reinforcing method for a vertical shaft formed by steel pipes. [Background technology]

[0002] In recent years, vertical shafts have been increasingly constructed using steel pipes (steel casings), particularly in urban areas. Steel casings of a predetermined length are swung or rotated with low noise even in environments with low altitude restrictions, and pressed into the ground. The ground inside the pressed-in steel casing is then excavated using a hydraulic grab or similar tool, and a vertical shaft is constructed that extends to a predetermined depth by successively adding steel casings. This construction method also makes it possible to construct vertical shafts that extend to great depths. A tunnel entrance is constructed, for example, on the lower side of the shaft formed by the installed steel pipes, and if the shaft is a departure shaft, a tunneling machine starts from the departure entrance into the ground and a tunnel is constructed using the jacking method or shield method, and if the shaft is a destination shaft, the tunneling machine that has constructed the tunnel into the ground will arrive at the destination entrance.

[0003] Mineheads such as departure and arrival mineheads require reinforcement around them depending on their depth, opening diameter, ground conditions, etc. However, in the construction method of pressing in a steel pipe and grab-excavating the inside of the steel pipe described above, if a member reinforcing the minehead is installed beforehand inside the steel pipe that forms the shaft, the reinforcing member will interfere with the grab-excavation, and there is a problem that the reinforcing member will be damaged due to interference between the two, so the opening reinforcement is carried out after the shaft is constructed. When a shaft is used as a departure shaft or arrival shaft, it is desirable to have a shaft entrance reinforcement structure that can safely reinforce the shaft entrance structurally on as small a scale as possible, from the perspective of ensuring sufficient space for installing various equipment to drive the tunneling machine inside the shaft, for dismantling and recovering the tunneling machine inside the shaft, and for ensuring sufficient space for installing precast members inside the shaft and constructing the main structure in the future.

[0004] Here, a shield tunnel structure and a construction method thereof are proposed in Patent Document 1. This shield tunnel structure is a shield tunnel structure in which openings for branch tunnels and the like are formed on the inner peripheral surface of a main tunnel excavated by a shield machine. A pair of reinforcing pillar members are provided on both the front and rear outer sides of the opening of a branch tunnel or the like in the axial direction of the main line tunnel, and upper and lower reinforcing beam members are provided at the upper and lower ends of the pair of reinforcing pillar members so as to straddle the reinforcing pillar members.The reinforcing pillar members are made up of segments, and the reinforcing beam members are set in reinforcing material assembly sections provided on the segments. Firestops are installed between the reinforcing column members and the reinforcing beam members, and the segment near the branch tunnel opening consists of a wall block that forms the inner wall of the main tunnel and an opening block where the branch tunnel opening is formed, and the opening block is made of a high-toughness concrete material that can be excavated with a shield tunneling machine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-235992 Summary of the Invention [Problem to be solved by the invention]

[0006] The shield tunnel structure described in Patent Document 1 is a structure that reinforces the opening in the shield tunnel where the branch tunnel is constructed, and therefore does not reinforce the entrance to the shaft formed by the steel pipe, and therefore does not disclose a means to solve the problems inherent in the shaft formed by the above-mentioned steel pipe.

[0007] The present invention aims to provide a shaft entrance reinforcement structure and a shaft entrance reinforcement method formed from steel pipes that can structurally and safely reinforce the shaft entrance on as small a scale as possible and ensure sufficient space inside the shaft after construction. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the shaft entrance reinforcement structure formed by steel pipes according to the present invention is as follows: A shaft entrance reinforcement structure formed by a steel pipe that reinforces a shaft entrance provided on a side wall of a shaft formed by a cylindrical steel pipe, A pair of reinforcing columns erected on the left and right sides of the pit entrance inside the vertical shaft; A pair of reinforcing beams arranged above and below the shaft entrance inside the shaft and joined to the pair of reinforcing columns; A plurality of arc-shaped first reinforcing ribs attached to the inside of the shaft at intervals in the height direction in a region opposite the shaft entrance within the height range of the shaft entrance, A plurality of annular second reinforcing ribs are attached to the inside of the shaft with gaps in the height direction in at least one of the upper and lower regions of the shaft entrance, The plurality of second reinforcing ribs are characterized in that they are provided in an area equivalent to the converted diameter of the wellhead in at least one of the areas above and below the wellhead.

[0009] According to this embodiment, by having a pair of reinforcing pillars erected on the left and right sides of the mine entrance, a pair of reinforcing beams arranged above and below the mine entrance and joined to the pair of reinforcing pillars, a plurality of arc-shaped first reinforcing ribs attached at intervals in the vertical direction in the area opposite the mine entrance within the height range of the mine entrance, and a plurality of annular second reinforcing ribs attached with gaps in the vertical direction in at least one of the areas above and below the mine entrance, the mine entrance can be structurally reinforced safely using relatively small reinforcing members, and sufficient space can be secured inside the shaft even after the mine entrance reinforcement structure is formed. In addition, by providing multiple second reinforcing ribs attached to the upper and lower areas of the wellhead in an area equivalent to the equivalent diameter of the wellhead in at least one of the upper and lower areas of the wellhead, it is possible to reinforce the wellhead in the area that requires the minimum amount of reinforcement.

[0010] Here, the "reinforcing beam" may be a reinforcing rib connecting a pair of reinforcing columns. Also, "a region equivalent to the equivalent diameter of the wellhead in at least one of the regions above and below the wellhead" means that if there is sufficient reinforcement region above and below the wellhead, the regions equivalent to the equivalent diameter both above and below the wellhead are the target, and if, for example, the wellhead is located below the shaft and there is not enough reinforcement region below, the region equivalent to the equivalent diameter above the wellhead is the target.

[0011] Another aspect of the shaft entrance reinforcing structure formed by the steel pipe according to the present invention is as follows: The lateral pressure acting on the shaft before the wellhead is installed is assumed to be distributed to the areas above and below the wellhead after the wellhead is installed, and the area within the height range of the wellhead and the areas above and below the wellhead that are equivalent to the converted diameter of the wellhead are each designed.

[0012] According to this aspect, the lateral pressure acting on the shaft before the mine entrance is installed is distributed to the areas above and below the mine entrance after the mine entrance is installed, and by designing the area within the height range of the mine entrance and the areas equivalent to the converted diameter above and below the mine entrance, a mine entrance reinforcement structure with high structural safety around the mine entrance after mirror cutting can be formed.

[0013] In another aspect of the shaft entrance reinforcing structure formed by the steel pipe according to the present invention, When the bottom plate of the shaft is present in an area equivalent to the converted diameter of the shaft entrance, the second reinforcing rib is not installed at the installation position of the bottom plate.

[0014] According to this embodiment, the installation position of the bottom slab of the shaft is reinforced by the bottom slab, so that the second reinforcing rib is not necessary and a rational shaft entrance reinforcement structure can be formed.

[0015] In another aspect of the shaft entrance reinforcing structure formed by the steel pipe according to the present invention, The shaft is characterized in that it is formed by a steel casing that is pressed into the ground and has its interior excavated.

[0016] According to this aspect, since the steel pipes constituting the shaft are steel casings, interference between the grab and the shaft entrance reinforcement member can be prevented during construction by pressing in the steel casing and excavating with a grab, and the shaft entrance reinforcement structure can be constructed quickly after the shaft is constructed.

[0017] In another aspect of the shaft entrance reinforcing structure formed by the steel pipe according to the present invention, The steel casing is characterized in that the areas between the multiple first reinforcing ribs and the areas between the multiple second reinforcing ribs each have a valved through hole for constructing protective work in the ground around the steel casing.

[0018] According to this aspect, valved through holes for constructing protective works on the ground around the steel casing are provided in the areas between the multiple first reinforcing ribs and the areas between the multiple second reinforcing ribs, so that various protective works can be constructed on the surrounding ground from inside the shaft entrance reinforcement structure. Here, protective works include various ground improvement methods such as chemical injection methods, freezing methods, and high-pressure spray methods.

[0019] In another aspect of the shaft entrance reinforcing structure formed by the steel pipe according to the present invention, The shaft is characterized in that it is a departure shaft from which a tunneling machine applied to the jacking method or the shield method departs, or a destination shaft to which the tunneling machine arrives.

[0020] According to this aspect, since the shaft on which the mine entrance reinforcement structure is to be constructed is either a departure shaft or a arrival shaft, sufficient space can be secured in the departure shaft for installing various equipment that drives the tunneling machine, and sufficient space can be secured in the arrival shaft for dismantling and recovering the tunneling machine once it has reached its destination. Furthermore, when various protective work is to be performed, sufficient space can be secured for installing facilities and equipment for the protective work.

[0021] Further, one aspect of the method for reinforcing the entrance of a shaft formed by a steel pipe according to the present invention is as follows: A method for reinforcing a shaft entrance formed by a steel pipe, which reinforces a shaft entrance provided on a side wall of a shaft formed by a cylindrical steel pipe, A pair of reinforcing columns erected on the left and right sides of the pit entrance inside the vertical shaft; A pair of reinforcing beams arranged above and below the shaft entrance inside the shaft and joined to the pair of reinforcing columns; A plurality of arc-shaped first reinforcing ribs attached to the inside of the shaft at intervals in the height direction in a region opposite the shaft entrance within the height range of the shaft entrance, A plurality of annular second reinforcing ribs are installed inside the shaft at least above or below the shaft entrance with gaps in the height direction, At that time, The method is characterized in that the plurality of second reinforcing ribs are installed in an area of ​​at least one of the wellheads, the area corresponding to the converted diameter of the wellhead.

[0022] According to this embodiment, by constructing a pair of reinforcing pillars erected on the left and right sides of the mine entrance, a pair of reinforcing beams arranged above and below the mine entrance and joined to the pair of reinforcing pillars, a plurality of arc-shaped first reinforcing ribs attached at intervals in the vertical direction in the area opposite the mine entrance within the height range of the mine entrance, and a plurality of annular second reinforcing ribs attached with gaps in the vertical direction in at least one of the areas above and below the mine entrance, the mine entrance can be structurally reinforced safely using relatively small reinforcing members, and sufficient space can be secured inside the shaft even after the mine entrance reinforcement structure is formed. In addition, by providing multiple second reinforcing ribs attached to the upper and lower areas of the wellhead in an area equivalent to the equivalent diameter of the wellhead in at least one of the upper and lower areas of the wellhead, it is possible to reinforce the wellhead in the area that requires the minimum amount of reinforcement. [Effects of the Invention]

[0023] According to the shaft entrance reinforcement structure and shaft entrance reinforcement method formed using steel pipes of the present invention, the shaft entrance can be structurally reinforced safely on as small a scale as possible, and sufficient space can be secured inside the shaft after construction. [Brief explanation of the drawings]

[0024] [Figure 1A] FIG. 1 is a plan view of an example of a unit of a transport vehicle and a rotating platform that constitutes a launch facility for constructing a branch tunnel according to an embodiment. [Figure 1B] 2 is a view taken along the arrow BB in FIG. 1, and is a side view of an example of a unit of a transport cart and a rotating platform. FIG. [Figure 1C] 2 is a view taken along the CC arrow in FIG. 1, and is a vertical cross-sectional view of an example of a unit of a transport cart and a rotating platform. FIG. [Figure 2A] FIG. 1 is an exploded view of an example of a tunnel excavator that starts from a launching facility for constructing a branch tunnel according to an embodiment, showing the front and rear bodies separately. [Figure 2B] FIG. 1 is an overall configuration diagram of an example of a tunnel excavator that starts from a launching facility for constructing a branch tunnel according to an embodiment. [Figure 3A] This is a diagram explaining the movement process and rotation process of the launch method of a tunnel boring machine for constructing a branch tunnel in an embodiment, and is a plan view showing an example of a transport cart equipped with a rotating platform on which the tunnel boring machine is mounted inside an existing tunnel, arriving at the branch tunnel construction position of the existing tunnel, and the rotating platform on which the tunnel boring machine is mounted being rotated on the transport cart. [Figure 3B] This is a diagram explaining the transport trolley removal process of the launching method for a tunnel boring machine for constructing a branch tunnel according to an embodiment, and is a plan view showing the state in which the tunnel boring machine is facing the excavation direction and the center level of the tunnel boring machine is aligned with the center level of the launch tunnel entrance in the existing tunnel. [Figure 4A] This is a view from the axial direction of the existing tunnel, showing a transport vehicle equipped with a rotating platform on which a tunneling machine is mounted, arriving at the branch tunnel construction position of the existing tunnel. [Figure 4B]This is a view from the axial direction of the existing tunnel, showing the rotating platform carrying the tunneling machine rotated on the transport cart at the branch tunnel construction position inside the existing tunnel, with the tunneling machine facing directly in the direction of excavation. [Figure 5A] 10A and 10B are diagrams illustrating in detail the rotation process of the starting method of the tunnel excavator for constructing a branch tunnel according to the embodiment. [Figure 5B] 5B is a diagram illustrating in detail the rotation process of the starting method of the branch tunnel construction machine according to the embodiment, following FIG. 5A. FIG. [Figure 5C] 5B, and is a diagram illustrating in detail the transport carriage removal step of the starting method of the branch tunnel construction machine according to the embodiment. FIG. [Figure 5D] 5C, and is a diagram illustrating in detail the transport carriage removal step of the starting method for the branch tunnel construction machine according to the embodiment. FIG. [Figure 5E] 5D, and is a diagram illustrating in detail the transport carriage removal step of the starting method for the branch tunnel construction machine according to the embodiment. FIG. [Figure 5F] 5E is a diagram illustrating in detail the transport carriage removal step of the starting method for the branch tunnel construction machine according to the embodiment. FIG. [Figure 6] 5F, is a plan view illustrating the mirror cutting step of the starting method of the branch tunnel construction machine according to the embodiment. FIG. [Figure 7A] 10A and 10B are diagrams illustrating in detail the mirror cutting process of the starting method of the tunnel boring machine for constructing a branch tunnel according to the embodiment. [Figure 7B] 7B is a diagram illustrating in detail the mirror cutting step of the starting method for the tunnel boring machine for constructing a branch tunnel according to the embodiment, following FIG. 7A. FIG. [Figure 7C] 7B is a diagram illustrating in detail the mirror cutting step of the starting method of the branch tunnel construction machine according to the embodiment. FIG. [Figure 7D] 7C is a diagram illustrating in detail the mirror cutting step of the starting method of the branch tunnel construction machine according to the embodiment. FIG. [Figure 7E]7D is a diagram illustrating in detail the mirror cutting step of the starting method for the tunnel boring machine for constructing a branch tunnel according to the embodiment. FIG. [Figure 7F] 7E is a diagram illustrating in detail the mirror cutting step of the starting method for the branch tunnel construction machine according to the embodiment. FIG. [Figure 8A] This is a diagram explaining an example of a backing prevention means and a rolling prevention means, viewed from the axial direction of the existing tunnel. [Figure 8B] 8B is a view taken in the direction of the arrow B in FIG. 8A, seen from the axial direction of the branch tunnel. [Figure 9A] FIG. 10 is a diagram illustrating the push-out process of the starting method of the branch tunnel construction machine according to the embodiment. [Figure 9B] 9B is a diagram illustrating the pushing-out step of the starting method of the branch tunnel construction machine according to the embodiment, following FIG. 9A. FIG. [Figure 9C] 9B is a diagram illustrating the pushing-out step of the starting method of the branch tunnel construction machine according to the embodiment. FIG. [Figure 10A] 10A to 10C are diagrams illustrating the ground improvement process, the access shaft entrance reinforcement formation process, and the cradle installation process of the method for recovering a tunneling machine in an access shaft according to an embodiment. [Figure 10B] 10B is a view seen in the direction of the arrow B in FIG. 10A, and is a plan view simulating the state in which the front body of the tunneling machine is mounted on the cradle. [Figure 10C] 10B is a view seen in the direction of the arrow C in FIG. 10A, and is a front view simulating the state in which the front body of the tunneling machine is mounted on the cradle. [Figure 11A] FIG. 2 is a plan view of an example of a wellhead reinforcement structure according to an embodiment. [Figure 11B] 11B is a view taken along the arrow BB in FIG. 11A, and is a front view of an example of an embodiment of a wellhead reinforcement structure around an access wellhead from inside the shaft. [Figure 11C] 11B is a view taken along the arrow CC in FIG. 11A, and is a vertical cross-sectional view of the shaft cut along a vertical plane passing through the center of the access wellhead. [Figure 12]10A and 10B are diagrams illustrating the low-strength solidified body creation process and the water filling process of the method for recovering a tunneling machine in an arrival shaft according to an embodiment. [Figure 13] 10A to 10C are diagrams illustrating the arrival process, gap closing process, and drainage process of the method for recovering a tunneling machine in an arrival shaft according to an embodiment. [Figure 14] 10A and 10B are diagrams illustrating the front body recovery process and the equipment recovery process of the tunneling machine recovery method in the arrival shaft according to the embodiment. [Figure 15] FIG. 10 is a diagram illustrating the state in which a branch tunnel has been constructed using the rear body of the tunneling machine and a group of tunnel boxes using the method for recovering the tunneling machine in the arrival shaft according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following describes, with reference to the accompanying drawings, the launching equipment for branch tunnel construction, the launching method for a tunneling machine for branch tunnel construction, the method for recovering the tunneling machine from the arrival shaft, and the shaft entrance reinforcement structure and method formed from steel pipes. Note that in this specification and drawings, substantially identical components may be designated by the same reference numerals to avoid redundant explanation.

[0026] [Starting equipment for branch tunnel construction and starting method for branch tunnel construction machine according to the embodiment] First, an example of a starting facility for constructing a branch tunnel and a starting method for a machine for constructing a branch tunnel according to an embodiment will be described with reference to Figs. 1 to 9 . Here, Fig. 1A is a plan view of an example of a unit of a transport cart and a rotating pedestal that constitutes a launching facility for constructing a branch tunnel according to an embodiment, Fig. 1B is a side view of an example of a unit of a transport cart and a rotating pedestal as viewed from the arrow BB in Fig. 1, and Fig. 1C is a longitudinal cross-sectional view of an example of a unit of a transport cart and a rotating pedestal as viewed from the arrow CC in Fig. 1. Also, Fig. 2A is an exploded view of an example of an excavator that launches from a launching facility for constructing a branch tunnel according to an embodiment, showing the front and rear bodies separately, and Fig. 2B is an overall configuration diagram of an example of an excavator that launches from a launching facility for constructing a branch tunnel according to an embodiment. Furthermore, Figure 3A is a diagram explaining the movement process and rotation process of the launch method of a tunneling machine for constructing a branch tunnel according to the embodiment, and is a plan view showing an example of a transport cart equipped with a rotating platform on which the tunneling machine is mounted inside an existing tunnel, arriving at the branch tunnel construction position of the existing tunnel, with the rotating platform on which the tunneling machine is mounted rotating on the transport cart; and Figure 3B is a diagram explaining the transport cart removal process of the launch method of a tunneling machine for constructing a branch tunnel according to the embodiment, and is a plan view showing a state in which the tunneling machine is facing directly in the excavation direction and the center level of the tunneling machine is aligned with the center level of the launch tunnel entrance of the existing tunnel. Furthermore, Figure 4A is a view from the axial direction of the existing tunnel, showing a transport cart equipped with a rotating platform on which a tunneling machine is mounted, arriving at the branch tunnel construction position of the existing tunnel, and Figure 4B is a view from the axial direction of the existing tunnel, showing a state at the branch tunnel construction position inside the existing tunnel, with the rotating platform on which the tunneling machine is mounted rotated on the transport cart so that the tunneling machine is facing directly in the direction of excavation.

[0027] The construction method for branch tunnels described below will be explained using the jacking method as an example, in which a tunnel boring machine is pushed into the ground using a main jack while tunnel boxes, which are thrust pipes, are connected and thrust forward in sequence, but branch tunnels may also be constructed using the shield method.

[0028] The illustrated example is a unit having a transport cart 10 equipped with wheels 12 that run along a pair of rails 34 laid inside an existing tunnel 30, and a rotating platform 16 that is mounted on a rotating shaft 14 that protrudes upward from the transport cart 10 and can rotate freely in the X2 direction within a horizontal plane.

[0029] A tunneling machine 20 used in the jacking method or shield method is mounted on a rotating platform 16, and as shown in Figure 3A, the transport cart 10 moves in the X1 direction along the rail 34 to the branch tunnel construction position 32 in the existing tunnel 30, and the rotating platform 16 is rotated in the X2 direction so that the tunneling machine 20 faces directly in the excavation direction of the tunneling machine 20 when constructing the branch tunnel 50.

[0030] The transport cart 10 and the rotating platform 16 are made of steel shaped materials such as H-shaped steel beams or steel plates, and an approximately cylindrical tunneling machine 20 is mounted between a pair of H-shaped steel beams at the top of the rotating platform 16.

[0031] 2A and 2B, the illustrated tunneling machine 20 comprises a front body 22 and a rear body 24. The front body 22 comprises a first front body 22A having a cutter disc and crushing cone rotatably attached to the tip of the shield body, a second front body 22B having a mud feed / discharge valve and a direction correction jack built into the shield body, and a cutter motor 22C. Meanwhile, the rear body 24 comprises a first rear body 24A having a gyroscope and other devices built into the shield body, and a second rear body 24B having a hydraulic unit and other devices built into the shield body.

[0032] Seal packings are provided at each connection position between the first front body 22A and the second front body 22B, and between the first rear body 24A and the second rear body 24B. In the illustrated example, the front body 22 and the rear body 24 are equipped with multiple elements, but the applicable tunneling machine may have one front body and one rear body, or may have each part built into a single shield body that is not divided into a front body and a rear body.

[0033] In the illustrated example, the front body 22 and rear body 24 of the tunneling machine 20 are equipped with multiple elements, and therefore each element is transported individually to the branch tunnel construction position 32 by a unit of the transport carriage 10 and the rotating platform 16, and then connected in sequence at the branch tunnel construction position 32 to form the tunneling machine 20. Note that the front body 22 to which the first front body 22A, the second front body 22B, and the cutter motor 22C are assembled may be transported by the transport carriage 10 to the branch tunnel construction position 32, and similarly, the rear body 24 to which the first rear body 24A and the second rear body 24B are assembled may be transported by the transport carriage 10 to the branch tunnel construction position 32 (these are the moving process).

[0034] If the entire tunnel excavator 20 were to be transported to the branch tunnel construction location 32 at once, a large transport cart and rotating platform would be required, but because the tunnel excavator 20 has a front body 22 and a rear body 24, the front body 22 and the rear body 24 can be transported separately, so a unit consisting of the smallest possible transport cart 10 and rotating platform 16 will suffice.

[0035] 3A shows the rotating platform 16 rotating with the front body 22 mounted on it. The existing tunnel 30 is a steel segment section in which the area including the branch tunnel construction position 32 is made of steel segments, and on both sides of that are reinforced concrete (RC) segment sections in which the tunnels are made of reinforced concrete segments, and a branch tunnel 50 will be constructed that branches off in a direction perpendicular to the steel segment section in plan view from the branch tunnel construction position 32.

[0036] Ground improvement GA has been applied to the ground G around the branch tunnel construction position 32 using protective work such as chemical injection and freezing methods. By applying the ground improvement GA, the risk of groundwater leaking into the existing tunnel 30 can be reduced when the tunneling machine 20 starts into the ground through the starting tunnel portal 31.

[0037] In the steel segment section, a plurality of sleepers 33 are installed at intervals in the axial direction of the existing tunnel 30, and a pair of rails 34 is laid on each sleeper 33. The pair of rails 34 extend to the lateral reinforced concrete segment section, and materials and equipment are suspended from the ground through a shaft (not shown) or the like through which the reinforced concrete segment section passes. The front body 22 and rear body 24 (or the first front body 22A and second front body 22B, the first rear body 24A and second rear body 24B, etc.) suspended from the ground are sequentially loaded onto the rotating platform 16 and transported by the transport cart 10 to the branch tunnel construction position 32.

[0038] A bearing wall 48 is installed on the wall surface behind the excavation direction at the branch tunnel construction position 32 of the existing tunnel 30, and the bearing wall 48 functions as a reaction support when the tunneling machine 20 and the tunnel box body are pushed into the ground by the main jack.

[0039] In the example shown in Figure 3A, a travel path is formed for the transport cart 10 to travel back and forth between the steel segment section and the RC segment section located on the right, and various equipment such as hydraulic units and control panels are installed in the RC segment section located to the left of the steel segment, and the layout of each piece of equipment is planned so that it does not interfere with the movement of the transport cart 10.

[0040] The launching equipment 90 for branch tunnel construction consists of a pair of rails 34 installed in the existing tunnel 30, a transport cart 10 that moves along the pair of rails 34 to the branch tunnel construction position 32, and a rotating platform 16 that is installed on the transport cart 10 and is freely rotatable with the tunneling machine 20 (including the front body 22 and rear body 24) mounted on it.

[0041] When rotating the rotating platform 16, as shown in Figures 4A and 4B, the transport cart 10 below is fixed to the existing tunnel 30 via a fixing lever block 35 (lever block: registered trademark), and then, for example, multiple workers (not shown) rotate the rotating platform 16 via a rotation lever block 36, thereby rotating the rotating platform 16 on which the front body 22 is mounted.

[0042] As shown in FIG. 4A, a starting hole 31 is provided at the starting position of the tunnel excavator 20 in the existing tunnel 30, and a hole entrance 40 for guiding the tunnel excavator 20 is installed at the starting hole 31.

[0043] As shown in Figure 3B, after the front body 22 faces the excavation direction, the transport carriage 10 is retracted sideways in the X1' direction, and the front body 22 is moved forward in the excavation direction using the rotating platform 16 as a launch platform. At the stage shown in Figure 3B, multiple height adjustment members 39 are installed below the rotating platform 16 from which the transport carriage 10 has been retracted, and the rotating platform 16 is placed on the multiple height adjustment members 39. In this state, the center level L1 of the launch tunnelhead 31 and the center level L2 of the tunneling machine are aligned, and the tunneling machine 20 is ready to start. 4B is the stage before the transport vehicle 10 is retracted, so the height adjustment member 39 has not been installed and the center level L1 of the departure tunnel entrance and the center level L2 of the tunneling machine do not coincide, after which the transport vehicle 10 is retracted, the height adjustment member 39 is installed, and the rotating platform 16 is placed on the height adjustment member 39, so that the center levels L1 and L2 coincide. The retraction of the transport vehicle 10 and level adjustment will be described in detail below.

[0044] Next, a starting method for a branch tunnel construction machine according to an embodiment will be described in detail with reference to Figures 5 to 9. Figures 5A and 5B are diagrams illustrating the rotation process in detail, and Figures 5C to 5F are diagrams illustrating the transport cart removal process in detail, following Figure 5B. Figure 6 is a plan view illustrating the mirror cutting process following Figure 5F, and Figures 7A to 7F are diagrams illustrating the mirror cutting process in detail, following Figure 5F. Figure 8A is a diagram illustrating an example of a backing prevention means and a rolling prevention means, viewed from the axial direction of the existing tunnel. Figure 8B is a view in the direction of arrow B in Figure 8A, viewed from the axial direction of the branch tunnel. Figures 9A, 9B, and 9C are diagrams illustrating the push-out process in detail, respectively.

[0045] As shown in Figure 5A, at the branch tunnel construction position 32, the transport cart 10 is fixed to the existing tunnel 30 via a fixing lever block 35, and then a rotation lever block 36 is attached to the rotating platform 16.As shown in Figure 5B, multiple workers (not shown) rotate the rotating platform 16 in the X2 direction to position the front body 22 directly in the excavation direction (this is the rotation process).

[0046] Next, as shown in Figure 5C, multiple jack stands 37 are installed below the rotating stand 16, and jacks 38 are installed on each jack stand 37. As shown in Figure 5D, the multiple jacks 38 are driven synchronously to jack up the rotating stand 16 upward in the X3 direction, making it possible to remove the transport cart 10.

[0047] Next, as shown in Figures 5E and 3B, the transport cart 10 is moved laterally along the pair of rails 34 to remove it from under the rotating platform 16, and a plurality of height adjustment members 39 made of H-shaped steel or the like are installed on the sleepers 33. The state shown in Figure 5E is the same as the state shown in Figure 4B.

[0048] Next, as shown in Figure 5E, the rotating platform 16 is jacked down in the X4 direction, and as shown in Figure 5F, the rotating platform 16 is placed on multiple height adjustment members 39, thereby aligning the center level L2 of the tunneling machine 20 (here, the front body 22) with the center level of the starting tunnel entrance 31 in the existing tunnel 30.

[0049] In other words, the height adjustment member 39 has a height such that when the rotating platform 16 is placed on the height adjustment member 39, the center levels L1 and L2 of both the members coincide with each other.

[0050] By making the center levels L1 and L2 coincide with each other in this way, the tunneling machine 20 can depart through the departure pithead 31 (this is the transport cart removal process).

[0051] Next, as shown in Figure 6, an entrance packing 41 is installed at the starting tunnel entrance 31, and the front body 22 is slid backward in the excavation direction X5 on the rotating platform 16, which serves as the starting platform, to perform mirror cutting. This will be explained in detail with reference to Figure 7A etc.

[0052] As shown in FIG. 7A, a temporary jack cradle 43C is installed on the front body 22, a temporary jack cradle 43A is installed on the launch platform 16 forward of the temporary jack cradle 43C, and one end of a temporary jack 43B is installed on the temporary jack cradle 43A.

[0053] Next, as shown in FIG. 7B, the temporary jack 43B is extended and the temporary jack cradle 43C is pushed rearward in the excavation direction X5 by the temporary jack 43B, thereby sliding the front body 22 rearward on the starting platform 16.

[0054] Next, as shown in Figure 7C, the temporary jack stand 43A is repositioned and installed relative to the starting stand 16, and the temporary jack 43B is repositioned and installed while the front body 22 is similarly pushed and slid rearward in the excavation direction in the X6 direction, thereby forming a work space S in front of the front body 22.

[0055] Next, as shown in FIG. 7D, the formed space S is used to install an entrance packing 41 at the wellhead entrance 40, and the wellhead side wall 30A is cut to perform mirror cutting (this is the mirror cutting process).

[0056] Furthermore, in order to push the front body 22 forward, in the opposite direction to Figures 7A to 7C, the temporary jack stand 43A is repositioned and installed rearward of the temporary jack support 43C on the starting platform 16, and one end of the temporary jack 43B is repositioned and installed on the temporary jack stand 43A.

[0057] Next, as shown in Figure 7E, the temporary jack 43B is extended and the temporary jack cradle 43C is pushed forward in the excavation direction in the X7 direction by the temporary jack 43B, causing the front body 22 to slide forward on the starting platform 16, and the front body 22 is pushed out to the minehead entrance 40 while the outer periphery of the front body 22 slides against the entrance packing 41. During this pushing out, the temporary jack platform 43A is also repositioned and installed relative to the starting platform 16, and the temporary jack 43B is also repositioned and installed, while the front body 22 is similarly pushed and slid forward in the excavation direction in the X7 direction.

[0058] As shown in FIG. 7F, the front body 22 is pushed out to the launch wellhead 31 formed by mirror cutting, thereby completing preparations for pushing out the front body 22.

[0059] Next, referring to Figures 8A and 8B, we will explain the means for preventing backing and rolling due to the earth pressure and groundwater acting on the front body 22 when the front body 22 is pushed into the ground (ground improvement GA).

[0060] As shown in Figures 8A and 8B, the backing prevention means 45 includes an extension beam 45A installed on a plurality of height adjustment members 39, a pair of support beams 45B installed on the plurality of extension beams 45A in a position spanning the front body 22, and an engagement jig 45C installed on a part of the support beams 45B and engaging with a part of the front body 22.

[0061] Meanwhile, the anti-rolling means 46 has a wire 46A that is fixed at one end to one of the support girders 45B and wound around the outer periphery of the front body 22, and a lever block 46B that is fixed to the other support girder 45B and applies tension to the wire 46A. Here, the pair of support girders 45B that form the backing prevention means 45 are also components of the anti-rolling means 46. The engaging jig 45C also functions as anti-rolling means for the front body 22. Note that above the wellhead entrance 40, lift-up prevention means 47 made of shaped steel or the like is attached to prevent the front body 22 from being lifted up.

[0062] As shown in FIG. 8A, three sets of anti-rolling means 46 are installed on the outer periphery of the forward body 22, and as the forward body 22 is pushed into the ground, the anti-rolling means 46 are removed in order, starting with the front.

[0063] As shown in Fig. 8A, backing prevention means 45 and rolling prevention means 46 are installed to prevent backing and rolling whenever the tunnel excavator 20, including the front and rear trunks 22 and 24 to be pushed out, and the tunnel box connected to the rear of the tunnel excavator 20, cannot obtain reaction force from the main push jack. For example, when connecting the rear trunk 24 to the front trunk 22, when installing the first tunnel box to the tunnel excavator 20, or when installing subsequent tunnel boxes sequentially, the rearmost tunnel excavator 20 or tunnel box cannot obtain reaction force from the main push jack, so backing prevention means 45 and rolling prevention means 46 are installed on the front trunk 22, rear trunk 24, tunnel box, etc. located near the minehead entrance 40.

[0064] Next, as shown in FIG. 9A, a push jack 49 is installed between the front body 22 and the bearing wall 48, and the push jack 49 is extended in the X8 direction to push the front body 22 forward in the excavation direction in the X9 direction (pushing process).

[0065] Next, as with the front body 22, the above-mentioned movement process, transport cart removal process, rotation process, and push-out process are carried out for the first rear body 24A, and the first rear body 24A is connected to the front body 22. As shown in Figure 9B, the main push jack 49 is extended in the X10 direction to push the front body 22 and the first rear body 24A forward in the excavation direction in the X11 direction.

[0066] Next, the above-mentioned moving process, transport cart removal process, rotation process, and push-out process are carried out for the second rear body 24B as with the front body 22 and the first rear body 24A, and the second rear body 24B is connected to the first rear body 24A to form the tunneling machine 20. As shown in Figure 9C, a main push jack unit 49A consisting of multiple main push jacks 49 is extended in the X12 direction, and the tunneling machine 20 is pushed forward in the excavation direction in the X13 direction.

[0067] Thereafter, the multiple tunnel boxes connected to the rear of the tunnel excavator 20 are pushed out in sequence in the same manner.

[0068] As described above, according to the method for starting a branch tunnel construction machine using the branch tunnel construction starting equipment 90 shown in the figure, the rotating platform 16 is rotatably mounted on the rotating shaft 14 protruding upward from the transport vehicle 10 which travels along the rails 34 laid inside the existing tunnel 30, and the tunneling machine 20 (including the front body 22 and rear body 24) is mounted on the rotating platform 16 and moved to the branch tunnel construction position 32, so that the tunneling machine 20 (and the front body 22) faces directly in the direction of excavation of the tunneling machine 20 when constructing the branch tunnel. By rotating the rotating platform 16 in this manner, after moving the tunnel excavator 20 (including the front body 22 and rear body 24) to the branch tunnel construction position 32, the tunnel excavator 20 (including the front body 22 and rear body 24) can be faced directly in the excavation direction by rotating the rotating platform 16, without having to load or unload the tunnel excavator 20 (including the front body 22 and rear body 24), and preparations for starting can be completed.This makes it possible to improve the efficiency of the series of operations from transporting the tunnel excavator 20 inside the existing tunnel 30 to starting it into the ground G.

[0069] [Method for recovering a tunneling machine from an access shaft according to an embodiment, and a shaft entrance reinforcement structure and a shaft entrance reinforcement method formed by steel pipes] Next, an example of a method for recovering a tunneling machine in an access shaft according to an embodiment, and a shaft entrance reinforcing structure and method formed from steel pipes will be described with reference to Figs. Here, Fig. 10A is a diagram illustrating the ground improvement process, the access wellhead reinforcement formation process, and the cradle installation process of the method for recovering a tunneling machine in an access shaft according to an embodiment, Fig. 10B is a view from the direction of arrow B in Fig. 10A, which is a plan view simulating the state in which the front body of the tunneling machine is mounted on the cradle, Fig. 10C is a view from the direction of arrow C in Fig. 10A, which is a front view simulating the state in which the front body of the tunneling machine is mounted on the cradle. Also, Fig. 11A is a plan view of an example of a wellhead reinforcement structure according to an embodiment, Fig. 11B is a view from the direction of arrow BB in Fig. 11A, which is a front view of an example of a wellhead reinforcement structure according to an embodiment around the access wellhead from inside the shaft, and Fig. 11C is a view from the direction of arrow CC in Fig. 11A, which is a vertical cross-sectional view of the shaft cut by a vertical plane passing through the center of the access wellhead. Fig. 12 is a diagram illustrating the low-strength solidified body creation process and the water filling process of the method for recovering a tunneling machine from an arrival shaft according to the embodiment, and Fig. 13 is a diagram illustrating the arrival process, gap closing process, and drainage process of the method for recovering a tunneling machine from an arrival shaft according to the embodiment. Furthermore, Fig. 14 is a diagram illustrating the front body recovery process and equipment recovery process of the method for recovering a tunneling machine from an arrival shaft according to the embodiment, and Fig. 15 is a diagram illustrating the state in which a branch tunnel has been constructed using the rear body of the tunneling machine and a group of tunnel boxes by the method for recovering a tunneling machine from an arrival shaft according to the embodiment.

[0070] As explained with reference to Figure 9C, the tunnel tunneling machine 20 and the tunnel box group 50A (see Figure 13) consisting of multiple tunnel boxes 51 following the tunnel tunneling machine 20 are pushed forward through the ground G by the main push jack unit 49A inside the existing tunnel 30, and the tunnel tunneling machine 20 reaches the arrival shaft 60 shown in Figure 10A.

[0071] The arrival shaft 60 shown in FIG. 10A is constructed by swinging or rotating a steel casing 61 (an example of a steel pipe) of a predetermined length t0 (e.g., approximately 1 m to 5 m) using a fully revolving machine (not shown) to press it into the ground G, and then excavating the ground inside the pressed-in steel casing 61 using a hydraulic grab (not shown) or similar device, and gradually adding more steel casings 61 to construct the shaft to a predetermined depth. Because the shaft is formed by multiple steel casings, it can be called a casing shaft. This construction method makes it possible to construct a shaft that extends to a great depth with low noise, even in environments with low airspace restrictions, such as urban areas.

[0072] Heavy machinery M such as a crawler crane is waiting on the ground to hoist and lift various materials and equipment.

[0073] A reinforced concrete bottom slab 64 is constructed below the access shaft 60, and an access shaft entrance 63 is formed in the lower side wall 62. A staircase 65 is also installed inside the access shaft 60 to allow workers to reach the bottom.

[0074] Of the arrival shafts 60, protective work such as chemical injection and freezing is carried out on the ground around at least the arrival wellhead 63 through which the arriving tunneling machine 20 enters, to create a ground improvement GC. A plurality of valved through-holes (not shown) are provided in the side wall 62 of the steel casing 61, and chemicals etc. are filled into the ground G around the arrival wellhead 63 through each valved through-hole.

[0075] By constructing ground improvement GC in the ground G at least around the access tunnel entrance 63, the risk of groundwater leaking when the tunneling machine 20 reaches the access shaft 60 via the access tunnel entrance 63 can be reduced (this is the ground improvement process).

[0076] Next, the area around the access wellhead 63 inside the arrival shaft 60 is reinforced and mirror cutting is performed. During this mirror cutting, a wellhead reinforcement structure 70 is constructed around the access wellhead 63 as shown in FIG. 10A. Here, the arrival shaft 60 in the illustrated example is constructed by repeatedly rotating and pressing a steel casing 61 and then grab-excavating the interior. Therefore, if the wellhead reinforcement structure 70 is installed in advance on the steel casing 61 that is rotated and pressed in at an early stage (the steel casing 61 in which the access wellhead 63 is formed), it will interfere with the grab excavation. Therefore, the wellhead reinforcement structure 70 is constructed after the arrival shaft 60 is constructed. The wellhead reinforcement structure 70 will be described in detail below.

[0077] After constructing the wellhead reinforcement structure 70 to reinforce the area around the access wellhead 63, part of the side wall 62 is mirror-cut to form the access wellhead 63 (this is the access wellhead reinforcement formation process).

[0078] Next, a support 80 is installed above the bottom slab 64 and below the access tunnel entrance 63 to receive and place the front body 22 of the tunneling machine 20 that has entered.

[0079] Here, the configuration of the cradle 80 will be described with reference to Figures 10B and 10C. Note that Figures 10B and 10C illustrate the tunneling machine 20 in a state where it has reached the arrival shaft 60, in order to simulate the state where the cradle 80 is carrying the front body 22.

[0080] The support base 80 has a pair of support girders 81 that directly support the front and rear of the forward body 22, multiple connecting girders 82 (three in the illustrated example) that connect the pair of support girders 81, and multiple fixing girders 83 (four in total in the illustrated example) that are spanned between the pair of support girders 81 and the side walls 62 of the arrival shaft 60 to fix the support base 80.

[0081] By installing a cradle 80 on which the front body 22 is placed on the bottom slab 64, the work of separating the front body 22 from the rear body 24 inside the arrival shaft 60 and the work of preparing to hoist the front body 22 to the ground are improved. Furthermore, it is possible to prevent the front body 22 of the tunneling machine 20 from tilting downward as it enters the arrival shaft 60, a phenomenon known as nose down (above, the cradle installation process).

[0082] 11A to 11C, the wellhead reinforcement structure 70 will be described. The wellhead reinforcement structure 70 has a pair of reinforcing columns 71 erected on the left and right of the access wellhead 63, a pair of reinforcing beams 72 arranged above and below the access wellhead 63 and joined to the pair of reinforcing columns 71, a plurality of arc-shaped first reinforcing ribs 74 attached to the interior of the access shaft 60 at intervals in the height direction in a region inside the access shaft 60 on the opposite side of the access shaft 63 within height range t1 of the access shaft 60, and a plurality of annular second reinforcing ribs 75 attached to the interior of the access shaft 60 at intervals in the height direction in at least one of the regions above and below the access shaft 63.

[0083] In the illustrated example, since the bottom slab 64 is located below the access wellhead 63 , the second reinforcing rib 75 is provided only above the access wellhead 63 .

[0084] The reinforcing column 71 in the illustrated example is formed from H-shaped steel, and the reinforcing beam 72 in the illustrated example is formed from reinforcing ribs fixed to the steel casing 61, but the reinforcing beam may also be formed from H-shaped steel like the reinforcing column.

[0085] Here, the plurality of second reinforcing ribs 75 are provided in the region above the access wellhead 63, within a range of a region t2 equivalent to the converted diameter t1 of the access wellhead 63.

[0086] In designing the mine entrance reinforcement structure 70, it is assumed that the lateral pressure (earth pressure and soil-water pressure) acting on the arrival shaft 60 before the arrival mine entrance 63 is installed will be distributed to the areas above and below the arrival mine entrance 63 (above in the illustrated example) after the arrival mine entrance 63 is installed, and an area within the range of height t1 of the arrival mine entrance 63 and an area t2 above the arrival mine entrance 63, equivalent to the converted diameter t1, are designed.Based on this design, the specifications of each of the pair of reinforcing columns 71 and reinforcing beams 72, and the specifications and number of the first reinforcing rib 74 and second reinforcing rib 75 are set.

[0087] The illustrated example of the tunnel entrance reinforcement structure 70 comprises a pair of reinforcing columns 71 erected on the left and right sides of the access tunnel entrance 63, a pair of reinforcing beams 72 arranged above and below the access tunnel entrance 63 and joined to the pair of reinforcing columns 71, a plurality of arc-shaped first reinforcing ribs 74 attached at intervals in the vertical direction in the area opposite the access tunnel entrance 63 within the range of height t1 of the access tunnel entrance 63, and a plurality of annular second reinforcing ribs 75 attached with gaps in the vertical direction in the area above the access tunnel entrance 63, all of which are relatively small-scale reinforcing members, allowing the access tunnel entrance 63 to be structurally and safely reinforced, and sufficient space can be secured inside the access shaft 60 even after the tunnel entrance reinforcement structure 70 is formed.

[0088] In addition, by providing a plurality of second reinforcing ribs 75 attached to the area above the access wellhead 63 in an area t2 equivalent to the equivalent diameter t1 of the access wellhead 63, it is possible to reinforce the wellhead in the area that requires the minimum amount of reinforcement.

[0089] Furthermore, the wellhead reinforcement structure 70 shown in the figure is reinforced by the bottom slab 64 at the installation position of the bottom slab 64 of the arrival shaft 60, thereby forming a rational wellhead reinforcement structure that does not require the second reinforcing rib 75 below the arrival wellhead 63. The wellhead reinforcement structure 70 can effectively reinforce the area around the arrival wellhead 63 even against the load during construction, and it is preferable to install each reinforcing member such as the reinforcing columns 71, reinforcing beams 72, first reinforcing rib 74, and second reinforcing rib 75 to a thickness and range required for the structure to withstand the load during construction. Furthermore, the reinforcing members within the cutting range will be removed after the final mirror cutting, but the reinforcing ribs can be left in place.

[0090] Following the cradle installation process, as shown in FIG. 12, a low-strength solidified body 91 that can be excavated by the tunneling machine 20 is created within the construction range of the wellhead reinforcement structure 70 in the arrival shaft 60.

[0091] The low-strength solidified body 91 is formed from fluidized soil, lean mortar, lean concrete, or the like.

[0092] By creating a low-strength solidified body 91 inside the arrival shaft 60 that can be excavated by the tunneling machine 20, it is possible to prevent the nose of the front body 22 from falling down when the tunneling machine 20 enters the arrival shaft 60, and the linearity of the rear body 24 that is left behind can be maintained at a predetermined linearity (above: low-strength solidified body creation process).

[0093] Next, at least water 93 is filled up to the groundwater level inside arrival shaft 60. In this way, after low-strength solidified body 91 is created inside arrival shaft 60, by filling at least water 93 inside arrival shaft 60 up to the groundwater level, it is possible to more reliably prevent groundwater from leaking into arrival shaft 60 (this is the water filling process).

[0094] Next, as shown in Figure 13, the front body 22 of the tunneling machine 20, which has been excavating in the Y1 direction through the ground G, is advanced into the arrival shaft 60 through the arrival shaft entrance 63, and the front body 22 moves forward while the cutter disk on the front of the front body 22 excavates the low-strength solidified body 91, and is placed on the receiving platform 80.

[0095] Next, filler material J is filled from inside the rear body 24 or the tunnel box body 51 into the gap between the rear body 24 and the tunnel box body 51 connected to the rear of the rear body 24 in the excavation direction and the surrounding ground improvement GC, thereby blocking the gap that serves as a water supply for groundwater.

[0096] In this way, by filling the gaps between the rear body 24, the tunnel box body 51 and the surrounding ground improvement GC with filler J, it is possible to more reliably prevent groundwater from leaking into the arrival shaft 60 (this is the gap sealing process).

[0097] Next, the water 93 filled inside the arrival shaft 60 is drained using the drainage pump P, and it is confirmed that there is no condensation inside the arrival shaft 60 during or after this drainage process. If condensation is confirmed, the gap blocking process is carried out again to block any remaining water. The water 93 inside the arrival shaft 60 is completely drained, and it is confirmed that there is no condensation (this concludes the drainage process).

[0098] Next, as shown in Figure 14, the low-strength solidified body 91 is excavated and removed using a hammer drill, shovel, excavator, etc. (not shown), the front body 22 is separated from the rear body 24, and the front body 24 is lifted in the Y3 direction by heavy equipment M on the ground and recovered.

[0099] The recovered front barrel 22 can be reused in the tunneling machine 20 used in a separate construction project (this is the front barrel recovery step).

[0100] Next, the equipment inside the rear fuselage 24 is detached from the rear fuselage 24 and, like the front fuselage 22, is lifted and recovered by heavy machinery M on the ground.

[0101] The recovered equipment can also be reused in the tunneling machine 20 to be used in other construction work (this concludes the equipment recovery process).

[0102] In this way, the equipment inside the front body 22 and the rear body 24 is recovered, and as shown in Figure 15, a branch tunnel 50 is constructed using the rear body 24 left underground and a tunnel box group 50A consisting of multiple subsequent tunnel box bodies 51.

[0103] As described above, according to the method for recovering a tunneling machine in the arrival shaft shown in the figure, when the front body 22 of the tunneling machine 20 reaches the arrival shaft 60, the front body 22 is separated from the rear body 24 and only the front body 22 is recovered, thereby enabling efficient recovery of the tunneling machine 20.

[0104] Furthermore, since only the forward body 22 is advanced into the arrival shaft 60 and separated from the rear body 24 for recovery, sufficient space can be secured for dismantling the forward body 22 even if the interior of the arrival shaft 60 is narrow.

[0105] Furthermore, since the rear trunk 24 is not recovered but is left in the state where it has reached the arrival shaft 60, it is possible to prevent groundwater from leaking into the arrival shaft when the rear trunk is further pulled into the arrival shaft.

[0106] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0107] 10: Transport cart 12: Wheels 14: Rotating axis 16: Rotating stand (launch stand) 20: Excavation machine 22: Front body 22A: 1st front torso 22B: 2nd front torso 22C: 3rd front torso 24: Rear body 24A: First rear fuselage 24B: 2nd rear torso 30: Existing tunnel 30A: Side wall for wellhead 31: Departure tunnel entrance (tunnel entrance) 32: Branch tunnel construction location 33: Sleeper 34: Rail 35: Fixing lever block 36: Rotating lever block 37: Jack stand 38: Jack 39: Height adjustment member 40: Mine entrance 41: Entrance gasket 43A: Temporary jack stand 43B: Temporary jack 43C: Temporary jack stand 45: Backing prevention measures 45A: Overhanging girder 45B: Support beam 45C: Engagement jig 46: Rolling prevention measures 46A: Wire 46B: Lever block 47: Floating prevention measures 48: Bearing wall 48A:Oshikaku 48B: Press ring 49: Push jack 49A: Main push jack unit 50: Branch Tunnel 60:Achievement shaft (vertical shaft) 61: Steel casing (steel pipe) 62: Side wall 63: Achieving wellhead (wellhead) 64: Bottom plate 65: Stairs 70: Pit reinforcement structure 71: Reinforcement pillar 72: Reinforced beam 74: First reinforcing rib 75: Second reinforcing rib 80: Cradle 81: Support beam 82: Connecting beam 83: Fixed digit 90: Launching equipment for branch tunnel construction (launching equipment) 91: Low strength solidified body 93:Water G: Ground GA,GC: Ground improvement L1: Center level of the starting tunnel entrance (center level) L2: Center level of the tunneling machine (center level) S: Space M: Heavy equipment P: Drainage pump

Claims

1. A shaft entrance reinforcement structure formed by a steel pipe that reinforces a shaft entrance provided on a side wall of a shaft formed by a cylindrical steel pipe, A pair of reinforcing columns erected on the left and right sides of the pit entrance inside the vertical shaft; A pair of reinforcing beams arranged above and below the shaft entrance inside the shaft and joined to the pair of reinforcing columns; A plurality of arc-shaped first reinforcing ribs attached to the inside of the shaft at intervals in the height direction in a region opposite the shaft entrance within the height range of the shaft entrance, A plurality of annular second reinforcing ribs are attached to the inside of the shaft with gaps in the height direction in at least one of the upper and lower regions of the shaft entrance, A shaft entrance reinforcement structure formed from steel pipes, characterized in that the multiple second reinforcing ribs are provided in an area equivalent to the equivalent diameter of the shaft entrance in at least one of the upper and lower areas of the shaft entrance.

2. A shaft entrance reinforcement structure formed from steel pipes as described in claim 1, characterized in that the area within the height range of the shaft entrance and the areas above and below the shaft entrance equivalent to the converted diameter of the shaft entrance are each designed based on the assumption that the lateral pressure acting on the shaft before the shaft entrance is provided is distributed to the areas above and below the shaft entrance after the shaft entrance is provided.

3. A shaft entrance reinforcement structure formed using steel pipes as described in claim 1 or 2, characterized in that if the bottom plate of the shaft is located in an area equivalent to the converted diameter of the shaft entrance, the second reinforcing rib is not installed at the installation position of the bottom plate.

4. 3. The shaft entrance reinforcement structure formed by steel pipes according to claim 1 or 2, characterized in that the shaft is constituted by a steel casing that is pressed into the ground and the inside of which is excavated.

5. The shaft entrance reinforcement structure formed by steel pipes as described in claim 4, characterized in that in the steel casing, in the areas between the plurality of first reinforcing ribs and in the areas between the plurality of second reinforcing ribs, there are provided valved through holes for constructing protective works in the ground around the steel casing.

6. The shaft entrance reinforcement structure formed by steel pipes as described in claim 5, characterized in that the shaft is a departure shaft from which a tunneling machine applied to the jacking method or the shield method departs, or a arrival shaft to which the tunneling machine arrives.

7. A method for reinforcing a shaft entrance formed by a steel pipe, which reinforces a shaft entrance provided on a side wall of a shaft formed by a cylindrical steel pipe, A pair of reinforcing columns erected on the left and right sides of the pit entrance inside the vertical shaft; A pair of reinforcing beams arranged above and below the shaft entrance inside the shaft and joined to the pair of reinforcing columns; A plurality of arc-shaped first reinforcing ribs attached to the inside of the shaft at intervals in the height direction in a region opposite the shaft entrance within the height range of the shaft entrance, A plurality of annular second reinforcing ribs are installed inside the shaft at least above or below the shaft entrance with gaps in the height direction, At that time, A method for reinforcing the entrance of a vertical shaft made of steel pipes, characterized in that a plurality of the second reinforcing ribs are installed in an area of ​​at least one of the entrances, the area being equivalent to the converted diameter of the entrance.

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