JP3783120B2 - Start method of shield excavator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for starting a shield excavator from a vertical shaft.
[0002]
[Prior art]
As is well known, when a tunnel is built in the ground with a shield excavator, a shaft is first constructed, and the shield excavator is started from this shaft toward a natural ground. At this time, an opening for starting the shield excavator is formed on the wall of the shaft, but the opening closes the gap between the inner peripheral surface and the outer peripheral surface of the shield excavator and enters the shaft such as earth and sand. Entrance packing is provided to prevent the inflow. Further, the shield excavator is provided with a tail seal that closes a gap between a segment assembled inside the shield excavator and an inner peripheral surface of a rear end portion of the shield excavator.
[0003]
By the way, in recent years, a technique for efficiently constructing a large-section tunnel using roads, railways, common grooves, and the like is being demanded. In order to meet this requirement, a tunnel structure that becomes the lining body of a large-section tunnel is constructed by constructing a plurality of shield tunnels adjacent to each other, and a space is created by excavating a natural ground inside the tunnel structure. The technology to build a large section tunnel by forming is being developed and proposed.
[0004]
In such a technique, after constructing one shield tunnel in advance, construct another shield tunnel in a position adjacent to it, but at this time, scraping the backfilling material of the shield tunnel constructed in advance while removing it. Let it polymerize.
In order to superimpose shield tunnels adjacent to each other, when constructing the shield tunnel to be constructed in advance, the diameter of the segment assembled inward to the hole drilled in the ground with a shield excavator is made smaller than usual. It is necessary to increase the lining thickness of the backfilling material to be filled between the hole and the segment. For this reason, the clearance gap between the inner side of the shield excavator for constructing the preceding shield tunnel and the outer peripheral surface of the segment assembled inside is larger than usual.
[0005]
However, when the gap between the inside of the shield excavator and the outer peripheral surface of the segment becomes large, when the shield excavator starts from the vertical shaft, the sand and sand flows into the vertical shaft after the shield excavator passes through the entrance packing. There is a problem of danger. In order to solve this, a technique disclosed in Japanese Patent Laid-Open No. 9-195672 has already been proposed.
[0006]
This technology relates to a starting method of a shield excavator, and solves the above-mentioned problem by closing the difference in size between the shield excavator and the outer periphery of the tunnel with a tunnel closing member attached to the entire circumference of the shaft opening. It is what I tried. This tunnel blocking member is made of a highly rigid plate, and is welded to a steel ring provided at a position corresponding to the tunnel blocking member in order to ensure the watertightness of the gap between the opening and the outer periphery of the tunnel. The structure is fixed to the tunnel.
[0007]
[Problems to be solved by the invention]
However, the conventional shield excavator starting method as described above has the following problems.
That is, in the technique disclosed in the above publication, the manufacturing cost of the tunnel blocking member is increased, and a steel ring must be installed to ensure water tightness. There is a problem that it takes time and effort.
Also, the tunnel closure member and the steel ring incorporated in the tunnel are fixed by welding etc., but in order to obtain a large thrust at the start of the shield excavator, to take a reaction force on the tunnel, As a result, the segments constituting the tunnel may move back and forth, and the welded portion between the tunnel closing member and the steel ring may be damaged. Then, water tightness cannot be maintained, and earth and sand and groundwater enter the shaft. In order to cope with this, it is conceivable that the tunnel closing member and the steel ring are more reliably joined, but this further increases the cost.
[0008]
Furthermore, in the technique of the above publication, after closing the gap between the opening and the outer periphery of the tunnel with the tunnel blocking member, mortar or the like is placed in the space surrounded by the opening, the tunnel blocking member, the tail seal, and the tunnel outer periphery. Although filled, the filling material such as mortar will protrude from the inner peripheral surface of the shaft, so it becomes an obstacle when forming the finished wall of the shaft, and it takes extra work to remove it There is.
[0009]
The present invention has been made in consideration of the above points, and provides a shield excavator start method that can easily prevent work and reduce costs while reliably preventing inflow of earth and sand. The issue is to provide.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 is a method of starting a shield excavator from a shaft, wherein a shaft structure wall constituting an inner wall surface of the shaft is formed, and the shield excavator is started on the shaft structure wall An opening is formed at the power position, and an entrance packing is provided in the vicinity of the opening to close the gap between the opening and the outer peripheral surface of the shield excavator. The shield excavator is started, and a tunnel is built therein, and a reaction force is obtained from the constructed tunnel to gradually advance forward in the excavation direction. When the opening of the wall is reached, a reinforcing bar is arranged between the opening and the outer peripheral surface of the tunnel built in the opening, and further concrete is placed, so that the opening and the tunnel are With the outer surface Closes between is characterized by forming a closed portion to integrate them.
[0011]
According to a second aspect of the present invention, in the starting method of the shield excavator according to the first aspect, when the shaft structure wall is formed, a joint fitting for connecting a rebar constituting the closed portion to the opening portion. It is characterized by burying.
[0012]
According to a third aspect of the present invention, in the starting method of the shield excavator according to the first or second aspect, when the closed portion is formed in a gap between the opening and the outer peripheral surface of the tunnel, the shield excavator is in contact with the outer peripheral surface of the tunnel. A water-stopping member for ensuring water-stopping is provided at the position.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of the first to fourth embodiments of the method for starting a shield excavator according to the present invention will be described with reference to FIGS. 1 to 13. Here, for example, when constructing a tunnel constituting a tunnel structure of a large cross-section tunnel, an explanation will be given using an example in which the start method of the shield excavator according to the present invention is applied.
[0015]
[First embodiment]
Here, a large-section tunnel to be constructed by applying the start method of the shield excavator according to the present invention will be described first.
[0016]
As shown in FIG. 1, the large-section tunnel 10 to be constructed has a left-right two-chamber structure, for example, has a large section such as a width of 30 m or more and a height of 15 m. It is composed of a tunnel structure 11 that resists, and left and right internal spaces (tunnel spaces) 12 and 13 formed inside the tunnel structure 11. In this tunnel structure 11, a preceding shield tunnel 15 and a trailing shield tunnel 16 each extending in a direction in which the large cross-section tunnel 10 continues are alternately arranged in the circumferential direction, and these partly overlap each other. It has an integrated structure.
[0017]
The preceding shield tunnel 15 is composed of one or two circular tunnel bodies (tunnels) 17 having a circular cross-sectional view, and two pairs of connecting portions extending in a horizontal direction from the tunnel body 17 toward the adjacent downstream shield tunnel 16. 18 and 18. The tunnel body 17 is configured by a plurality of segments 19 assembled in a circular shape. The space between the tunnel body 17 and the outer ground G of the tunnel body 17 and the space that forms the connecting portion 18 include concrete or mortar. A backfilling material 20 such as fiber concrete is filled.
[0018]
The trailing shield tunnel 16 has a circular shape in cross section, and is composed of a segment 22 assembled in a circular shape and a backfill material 23 filled between the surrounding ground G.
[0019]
As described above, the tunnel structure 11 of the large-section tunnel 10 includes the leading shield tunnel 15 and the trailing shield tunnel 16 alternately arranged in the circumferential direction, and is integrated via the connecting portions 18 and 18 of the leading shield tunnel 15. Further, the inside thereof is filled with a reinforcing material 24 such as a reinforcing bar or PC steel and a concrete 25.
[0020]
Here, the shield excavator used for construction of the special shape preceding shield tunnel 15 having the connecting portion 18 will be described.
For the construction of each preceding shield tunnel 15, a shield excavator 30 as shown in FIG. 2 is used. The shield excavator 30 has an outer shell formed by a skin plate 31, which has a substantially circular cross-section skin plate body 31 a corresponding to the tunnel body 17 (see FIG. 1) of the preceding shield tunnel 15, and a tunnel. The projecting portion 31b has a substantially oval cross section corresponding to each connecting portion 18 (see FIG. 1) extending from the main body 17, and has a substantially H shape as a whole.
[0021]
The front portion of the skin plate body 31a of the skin plate 31 is provided with a main cutter 32 provided with a number of cutter bits 32a, as in a normal shield excavator, and behind this main cutter 32 is driven to rotate. A cutter driving mechanism, a soil removal mechanism, a shield jack for propelling the shield excavator 30 and a segment assembling device are provided.
[0022]
For example, two small-diameter cutters 33 having substantially the same diameter as the short diameter of the overhanging portion 31b are provided in front of each overhanging portion 31b of the skin plate 31. Each of the small-diameter cutters 33 is rotationally driven by a drive mechanism provided at the rear thereof, and is supported by an arm (not shown) so as to be movable in the long-diameter direction of the overhanging portion 31b (direction perpendicular to the axis of the skin plate 31). It has become. Then, the small-diameter cutter 33 is driven to rotate and is moved in the major axis direction of the overhanging portion 31b by an arm (not shown), thereby excavating the natural ground G into a substantially oval cross section, and the connection shown in FIG. A portion 18 is formed.
[0023]
Further, in the rear portion of the overhanging portion 31b, a backfilling material 20 (see FIG. 1) such as concrete, mortar, or fiber concrete is placed and filled on the outer peripheral side of the segment 19 of the tunnel body 17 and the connecting portions 18 and 18. A backfill filler placing tube 34 for performing the above and a backfill filler pressing mechanism 35 for maintaining the pressure of the backfilled filler 20 that has been placed and filled (see FIG. 1) are provided.
[0024]
Next, a method for constructing such a large-section tunnel 10 will be described.
For this purpose, first, as shown in FIG. 3, only the preceding shield tunnels 15, 15,... Constituting the tunnel structure 11 are constructed in advance.
[0025]
In order to construct each preceding shield tunnel 15 in advance, first, the shield excavator 30 shown in FIG. 2 is propelled to rotate the main cutter 32 while rotating the small-diameter cutter 33 on the outer peripheral side and overhanging. By moving in the major axis direction of the part 31b, as shown in FIG. 3, a hole 38 having a cross-sectional shape corresponding to the preceding shield tunnel 15 including the tunnel body 17 and the connecting parts 18, 18,. Then, at the rear side in the skin plate 31 (see FIG. 2), the segment 19 is assembled into a predetermined shape in the hole 38, and the backfill filler placing pipe 34 (see FIG. 2), the backfill filler 20 is filled, and this is pressed by the backfill filler press mechanism 35 (see FIG. 2) and kept at a predetermined pressure, whereby the tunnel main body 17 of the preceding shield tunnel 15 is obtained. And the connecting parts 18, 18,... Are constructed.
[0026]
After constructing the preceding shield tunnels 15, 15,... At predetermined positions, circular holes 39, 39,... Are drilled using a shield excavator (not shown) having a circular cross-sectional view. At this time, a part of the backfilling material 20 that forms the connecting portions 18 and 18 of the preceding shield tunnel 15 is also shaved together with the ground G between the preceding shield tunnels 15 and 15. As shown in FIG. 4, while excavating each hole 39, the segments 22, 22,... Are assembled behind the shield excavator (not shown), and concrete, mortar, fiber concrete is formed on the outer peripheral side of the assembled segment 22. The back shield tunnel 16 is constructed in each hole 39 by filling the backfill material 23 such as.
[0027]
As a result, the preceding shield tunnel 15 and the trailing shield tunnel 16 having a circular cross-sectional view are alternately arranged in the circumferential direction, and the leading shield tunnel 15 and the trailing shield tunnel 16 are partially overlapped with each other. Become.
[0028]
Subsequently, as shown in FIG. 1, reinforcing members 24 are arranged in the constructed tunnel structure 11 and concrete 25 is placed and filled. Thereby, the tunnel structure 11 is completed. After that, the natural ground G inside the tunnel structure 11 is excavated and the internal spaces 12 and 13 are formed therein, thereby completing the construction of the large-section tunnel 10 having a predetermined shape.
[0029]
By the way, as shown in FIG. 5, when constructing the large section tunnel 10 by the above construction method, the leading shield tunnel 15 and the trailing shield tunnel 16 (see FIG. 1) are constructed from the vertical shaft 40 constructed at a predetermined position. To start. At this time, particularly in the shield excavator 30 for constructing the preceding shield tunnel 15, since the gap between the skin plate 31 and the segment 19 assembled inside thereof is large, the following starting method is adopted.
[0030]
As shown in FIG. 5 and FIG. 6, the shaft 40 formed by excavating at a predetermined start position resists earth pressure and water pressure from the surrounding natural ground G. The retaining wall 41 is formed by various methods. Furthermore, the shaft structure wall 42 used as the finishing wall of the shaft 40 is formed in the inner peripheral surface side of the earth retaining wall 41, for example with a reinforced concrete structure. In the earth retaining wall 41 and the shaft structure wall 42, an opening 43 larger than the outer diameter of the shield excavator 30 is formed at the start position of the shield excavator 30, and a portion exposed by the opening 43 is formed. The natural ground G is cured by various methods such as a chemical solution injection method.
[0031]
As shown in FIG. 6, the opening 43 </ b> B formed in the shaft structure wall 42 is made larger than the opening 43 </ b> A formed in the retaining wall 41 by a predetermined dimension. Further, a joint fitting 44 for connecting reinforcing bars faces the opening 43B in the opening 43B of the shaft structure wall 42, and is attached to the end of the reinforcing bar S constituting the shaft structure wall 42.
[0032]
After forming the shaft 40 in this way, as shown in FIG. 5, the shield excavator 30 penetrates the segment 19 assembled in the shaft 40 from the opening 43 toward the natural ground G by reaction force. I will let you. At this time, as shown in FIG. 6, the entrance packing 45 is attached to the retaining wall 41 around the opening 43 </ b> A, and the outer peripheral surface of the skin plate 31 of the shield excavator 30 and the shield excavator 30 are excavated. The earth and sand and groundwater are blocked from entering the shaft 40 through the gap with the hole 38. The entrance packing 45 is made of a flexible material such as a rubber material, and its base end is fixed by a fixing member such as a plate-like pressing jig 46 and a bolt 47. The holding jig 46 is slidably attached in the radial direction of the hole 38.
[0033]
Further, the gap between the skin plate 31 of the shield excavator 30 and the segment 19 assembled inside thereof is closed by a tail seal 48 provided in advance at the rear end of the skin plate 31.
[0034]
While excavating the natural ground G with this shield excavator 30, the segment 19 is assembled behind it to form the tunnel main body 17, and the tunnel main body 17 gains reaction force and gradually advances into the natural ground G. . Then, as shown in FIG. 7, when the rear end portion of the skin plate 31 of the shield excavator 30 reaches substantially the same surface as the inner peripheral surface 41 a of the retaining wall 41 and reaches a position where it does not come off the entrance packing 45. Then, the excavation is temporarily stopped.
[0035]
Next, as shown in FIG. 8, a rebar unit (rebar) 49 assembled in advance in a predetermined shape is connected to the joint fitting 44 exposed at the opening 43B of the shaft structure wall 42, thereby opening the opening 43B. And the tunnel body 17 assembled inward thereof.
[0036]
Subsequently, as shown in FIG. 9, molds (not shown) are set between the rear end of the shield excavator 30 and the tunnel main body 17, and between the opening 43 </ b> B of the shaft structure wall 42 and the tunnel main body 17. Then, the concrete 50 is placed in the formwork. The concrete 50 and the reinforcing bar 49 form a reinforced concrete blockage 51 in the gap between the opening 43B and the inner tunnel body 17 to block the gap and the shaft wall 42 and the tunnel. The main body 17 is integrated.
[0037]
After the blocking portion 51 is formed in this way, as shown in FIG. 10, the excavation of the shield excavator 30 is resumed and the tunnel main body 17 is assembled at the rear, while the backfilling material placing pipe 34 and the back By filling the space between the hole 38 and the tunnel body 17 with the backfilling material 20 by the filling filler pressing mechanism 35 (see FIG. 2) or the like, the tunnel body 17 is extended and constructed. At this time, as usual, the tail seal 48 provided on the skin plate 31 of the shield excavator 30 is used to remove dirt, groundwater, etc. from the gap between the skin plate 31 of the shield excavator 30 and the inner tunnel body 17. Intrusion into 31 is prevented.
[0038]
In the start method of the shield excavator 30 described above, the opening 43 having the entrance packing 45 is formed in the shaft structure wall 42, and the shield excavator 30 is started from the opening 43 toward the natural ground G. When the rear end reaches the opening 43, a reinforcing bar unit 49 is arranged between the opening 43 and the outer peripheral surface of the tunnel main body 17 assembled inward thereof, and the concrete 50 is placed. By this, it becomes the structure which forms the obstruction | occlusion part 51 of a reinforced concrete structure. By this blocking portion 51, the gap between the opening 43 and the tunnel body 17 can be completely blocked, and it is possible to reliably prevent the earth and sand, groundwater and the like from entering the shaft 40 from here. Further, such a reinforced concrete blocking portion 51 completely integrates the shaft structure wall 42 and the tunnel body 17, so that when the tunnel body 17 receives the driving force of the shield excavator 30, the shaft structure wall It is possible to prevent damage to the joint portion between 42 and the blocking portion 51 or between the blocking portion 51 and the tunnel main body 17 and to maintain water stopping performance.
[0039]
By the way, in the technique disclosed in Japanese Patent Laid-Open No. 9-195672 mentioned as the conventional example, a bracket is provided on the shaft structure side in order to attach a tunnel closing member for closing the gap between the opening and the tunnel. In addition, it is necessary to incorporate a steel segment only at the location where the tunnel closing member is attached to the tunnel, and extra time is required. Furthermore, in this conventional technique, the tunnel blocking member is provided so as to protrude from the inner surface of the shaft structure to the inside of the shaft, and after closing the gap between the opening and the tunnel outer periphery with the tunnel blocking member, Therefore, it is necessary to remove it and close the opening, and this also requires extra work.
On the other hand, according to the above-described configuration, the closing portion 51 is made of reinforced concrete, and this becomes the main installation as it is and forms a part of the shaft structure wall 42. Therefore, the opening 43 and the tunnel body 17 are formed. Therefore, it is not necessary to use a special temporary member for closing the gap, and it is possible to reduce costs and shorten the work period by omitting extra labor.
[0040]
The opening 43 of the shaft structure wall 42 has a structure in which a joint fitting 44 for connecting a reinforcing bar unit 49 constituting the closing portion 51 is embedded. Thereby, the reinforcing bar unit 49 and the reinforcing bar S of the shaft structure wall 42 can be easily connected, and the shaft structure wall 42 and the blocking portion 51 can be integrated reliably. Furthermore, since the reinforcing bar unit 49 assembled in advance in a predetermined shape is used, the efficiency of construction can be improved.
[0041]
[Second Embodiment]
Next, a second embodiment of the shield excavator start method according to the present invention will be described. In the description below, the basic configuration of the shield excavator starting method is exactly the same as in the first embodiment, so only the differences from the first embodiment will be described and the common configuration will be described. Are denoted by the same reference numerals, and the description thereof is omitted.
[0042]
As shown in FIG. 11, as in the first embodiment, an opening 43 is formed in the shaft structure wall 42, and the shield excavator 30 is penetrated from the opening 43 into the natural ground G. When the rear end of the skin plate 31 reaches substantially the same surface as the inner peripheral surface 41a of the retaining wall 41 and reaches a position where it does not come off the entrance packing 45, the reinforcing bar unit 49 is arranged. At the same time, on the outer peripheral surface of the tunnel main body 17 formed by assembling the segments 19, ring-shaped seal members (water-stop members) 55 made of a rubber material or the like are disposed, for example, in a triple manner. After that, concrete 50 is placed here to form a closed portion 51 '.
[0043]
After the blocking portion 51 ′ is thus formed and the gap between the hole 38 and the tunnel body 17 is closed, the tunnel is extended and constructed by the shield excavator 30 in the same manner as in the first embodiment. .
[0044]
According to the starting method of the shield excavator 30 described above, by providing the blocking portion 51 ′, the same effects as those of the first embodiment can be obtained, and the following remarkable effects can be obtained. . That is, the sealing member 55 is disposed at a position where the blocking portion 51 ′ contacts the outer peripheral surface of the tunnel body 17. When the concrete 50 is cured, the temperature is increased and cured, and then the temperature is decreased and the volume of the concrete 50 is contracted. Further, since the reaction force for propulsion is applied to the tunnel main body 17 when the shield excavator 30 is propelled, a large compressive force is applied to the tunnel main body 17, but the force applied to the tunnel main body 17 is reduced after the propulsion is completed. As a result, the tunnel body 17 expands and contracts in the front-rear direction (digging direction). When the volumetric shrinkage of the concrete 50 and the expansion and contraction of the tunnel body 17 occur, the concrete 50 forming the blocking portion 51 ′ and the joining surface of the tunnel body 17 are cut off to create a gap, thereby causing water leakage. Although there is a fear, by providing the sealing member 55 on the joining surface as described above, even if the joining surface is cut off and a gap is generated, the sealing member 55 can maintain the water-stopping property. it can. Therefore, even if a gap is formed at the joint between the blocking portion 51 ′ and the tunnel due to the shrinkage and the propulsive force of the shield excavator as shown in the first embodiment, this gap is caused by the seal member 55. Therefore, it is possible to prevent water leakage or the like from occurring in the shaft 40.
[0045]
[Third embodiment]
Next, a description will be given of a third embodiment of the shield excavator start method according to the present invention. In the description below, the basic configuration of the shield excavator starting method is exactly the same as in the first embodiment, so only the differences from the first embodiment will be described and the common configuration will be described. Are denoted by the same reference numerals, and the description thereof is omitted.
[0046]
As shown in FIG. 12, an opening 43 is formed in the shaft structure wall 42 as in the first embodiment, and the shield excavator 30 is penetrated from the opening 43 into the natural ground G. When the rear end of the skin plate 31 reaches substantially the same surface as the inner peripheral surface 41a of the retaining wall 41 and reaches a position where it does not come off the entrance packing 45, the reinforcing bar unit 49 is arranged. At the same time, a sealing material (water blocking member) 57 is disposed in a layered manner on the outer peripheral surface of the assembled tunnel body 17. After that, concrete 50 is placed here to form a closed portion 51 ″.
[0047]
The sealing material 57 is disposed over the entire area of the concrete 50, the tunnel main body 17 and the joining surface. The sealing material 57 has water-stopping properties, and the tunnel main body 17 and the concrete 50 are connected to the tunnel main body 17. It is preferable that the sheet material 57 itself deforms to follow the relative displacement or absorb the relative displacement when it is relatively displaced in the direction along the surface. More specifically, as the sealing material 57, for example, a waterproof asphalt is heated to be in a liquid state, and this is applied to or sprayed on the outer peripheral surface of the tunnel body 17, and cured, such as a rubber system for caulking or the like. A plastic material applied to the outer peripheral surface of the tunnel body 17, a urethane material used as a heat insulating material, etc., sprayed onto the outer peripheral surface of the tunnel main body 17 and cured, a rubber type or a plastic type There is a sheet material attached to the outer peripheral surface of the tunnel body 17 with an adhesive or the like. Any other material can be used as long as the material can cope with the relative displacement between the tunnel body 17 and the concrete 50 when interposed between the tunnel body 17 and the concrete 50. It doesn't matter what the fixing method is.
[0048]
According to the starting method of the shield excavator 30 as described above, when the gap between the opening 43 of the shaft structure wall 42 and the assembled tunnel body 17 is blocked by the blocking portion 51 ", the blocking portion 51" is formed. Between the concrete 50 and the outer peripheral surface of the tunnel main body 17, it has the structure which inserts the sealing material 57 which has a water stop and can deform | transform. Thereby, in addition to the effect shown by said 1st and 2nd embodiment, there can exist the following effects. That is, as shown in the second embodiment, when the volume shrinkage of the concrete 50 or the expansion and contraction of the tunnel body 17 occurs, the adhesion between the joint surface of the concrete 50 and the tunnel body 17 may be cut off. Sometimes, it is conceivable that the concrete 50 is pulled and cracks or the like are generated when the joining surface is not completely attached or when the surface of the tunnel main body 17 is uneven. On the other hand, by interposing the layered sealing material 57 between the concrete 50 and the tunnel main body 17, even if volume shrinkage of the concrete 50 or expansion / contraction of the tunnel main body 17 occurs, the concrete 50 and the tunnel When the relative displacement between the concrete 50 and the tunnel body 17 occurs, the sealing material 57 interposed between them deforms following the relative displacement or is displaced relative to the body 17. The concrete 50 is not subjected to any stress due to its displacement. Moreover, even if the relative displacement between the concrete 50 and the tunnel main body 17 occurs, the concrete 50 can be deformed following the displacement, and the relative displacement can be absorbed by the deformation. Therefore, damage or the like of the concrete 50 can be prevented, and water stoppage can be reliably ensured.
[0049]
[Fourth embodiment]
Next, a description will be given of a fourth embodiment of the method for starting a shield excavator according to the present invention. In the description below, the basic configuration of the shield excavator starting method is exactly the same as in the first embodiment, so only the differences from the first embodiment will be described and the common configuration will be described. Are denoted by the same reference numerals, and the description thereof is omitted.
[0050]
As shown in FIG. 9, as in the first embodiment, an opening 43 is formed in the shaft structure wall 42, and the shield excavator 30 is inserted into the natural ground G from the opening 43. When the rear end of the skin plate 31 reaches substantially the same surface as the inner peripheral surface 41a of the retaining wall 41 and reaches a position where it does not come off the entrance packing 45, the reinforcing bar unit 49 'is arranged and the concrete 50 Is formed, and after the gap between the hole 38 and the tunnel main body 17 is closed by the closing portion 51, the tunnel is extended and constructed by the shield excavator 30. There is no difference from the one embodiment.
[0051]
The difference from the first embodiment is that, for example, a reinforcing bar unit 49 ′ constituting the blocking portion 51, which is scraped off by a shield excavator (not shown) for constructing the trailing shield tunnel 16, A material that can be cut with a shield excavator, such as a resin that can be cut with a shield excavator, such as a holding jig 46 of the entrance packing 45 and, if necessary, a rebar S 'that constitutes the shaft structure wall 42, is used. The purpose is to form the material made of carbon fiber or glass fiber hardened with plastic.
[0052]
By the way, when constructing the trailing shield tunnel 16 after constructing the leading shield tunnel 15 as shown in FIG. 1, as shown in the first embodiment, a part of the leading shield tunnel 15 is formed. By cutting off, the leading shield tunnel 15 and the trailing shield tunnel 16 are superposed on each other. At this time, with the configuration as described above, excavation at the time of construction of the trailing shield tunnel 16 can be easily performed, and the construction cost and construction period of the large-section tunnel 10 can be suppressed.
[0053]
Note that the configurations described in the first to fourth embodiments can adopt other configurations as appropriate without departing from the gist of the present invention.
For example, the reinforcing bar unit 49 assembled in a predetermined shape is used, but the reinforcing bars may be arranged while being assembled on the spot.
[0054]
Further, in order to more reliably join the blocking portions 51, 51 ′, 51 ″ and the tunnel body 17 or the retaining wall 41, stud members or the like are disposed on the tunnel body 17, the retaining wall 41, or the like. Also good.
[0055]
Furthermore, in the first to fourth embodiments described above, the shield excavator excavation method according to the present invention is applied to the preceding shield tunnel 16 that constitutes the large cross-section tunnel 10. As long as the gap with the tunnel body 17 to be assembled on the other side, that is, when the lining thickness of the backfilling material 20 is thick, the target tunnel may be anything. For example, as shown in FIG. 13, the tunnel body 17 ′ of the preceding shield tunnel 15 ′ constituting the large cross-section tunnel 10 ′ may have another shape such as a substantially rectangular shape instead of a circular shape in cross section. In addition to this, the shield excavator start method according to the present invention can be applied to tunnels of any configuration and shape, and of course can be applied to a normal single shield tunnel as well. Is possible. Further, there is no intention to limit the configuration of the shield excavator used at that time, and any configuration may be used.
[0056]
In addition to this, it is needless to say that any configuration may be adopted as long as it does not depart from the gist of the present invention, and the above-described configurations may be appropriately combined.
[0057]
【The invention's effect】
As described above, according to the starting method of the shield excavator according to the first aspect, the opening having the entrance packing is formed in the shaft structure wall, and the shield excavator is directed from the opening toward the natural ground. After the rear end passes through the opening, a reinforced concrete blockage is formed between the opening and the outer peripheral surface of the tunnel built inside the opening. By this blocking portion, the gap between the opening portion and the tunnel built inside the opening portion can be blocked, and it is possible to prevent earth and sand and groundwater from entering the shaft. In addition, the reinforced concrete blockage completely integrates the shaft wall and tunnel, so the propulsion reaction force of the shield excavator damages the shaft wall and blockage or the junction between the block and tunnel. Can be prevented. In addition, since this closed portion is directly installed and constitutes a part of the shaft structure wall, it is not necessary to use a temporary member for closing the gap between the opening and the tunnel, and unnecessary labor is saved. Significantly lower costs and shorter construction time can be achieved.
[0058]
According to the start method of the shield excavator according to claim 2, when forming the shaft structure wall, the opening has a structure in which a joint fitting for connecting a reinforcing bar constituting the closed portion is buried. Yes. Thereby, it is possible to easily attach the reinforcing bars constituting the closed portion, and it is possible to reliably integrate the shaft structure wall and the closed portion. Furthermore, if a reinforcing bar unit or the like assembled in advance in a predetermined shape is used for the reinforcing bar, the construction can be further facilitated.
[0059]
According to the shield excavator start method of the third aspect, when the closed portion is formed, a water stop member for securing water stop is provided at a position in contact with the outer peripheral surface of the tunnel. . As a result, even if there is a gap in the junction between the closed part and the tunnel due to shrinkage during hardening of the concrete or the propulsion force of the shield excavator, water leakage or the like may occur in the shaft due to this gap. Can be prevented.
[Brief description of the drawings]
FIG. 1 is an elevational sectional view showing an example of a tunnel constructed by applying a starting method of a shield excavator according to the present invention.
FIG. 2 is a perspective view showing an example of a shield excavator used when excavating the tunnel.
FIG. 3 is a view showing the excavation method of the tunnel, and an elevational sectional view showing a state in which a preceding shield tunnel is constructed.
FIG. 4 is an elevational sectional view showing a state where a trailing shield tunnel is constructed by partially superposing the preceding shield tunnel.
FIG. 5 is a diagram showing a start method of the shield excavator, and is a perspective view showing a state where an opening is formed in the shaft and the shield excavator is about to start toward the opening.
FIG. 6 is a side sectional view showing a state in which the shield excavator has started to penetrate into the natural ground from the opening.
FIG. 7 is a side sectional view showing a state in which the excavation of the shield excavator is once stopped.
FIG. 8 is a side sectional view showing a state in which a reinforcing bar is arranged in the opening.
FIG. 9 is a side sectional view showing a fourth embodiment of a starting method for a shield excavator according to the present invention, showing a state in which concrete is placed in the opening to form a closed portion. .
FIG. 10 is a side sectional view showing a state where the shield excavator resumes excavation.
FIG. 11 is a side sectional view showing a second embodiment of the starting method of the shield excavator according to the present invention.
FIG. 12 is a side sectional view showing a third embodiment of the starting method of the shield excavator according to the present invention.
FIG. 13 is a vertical sectional view showing another example of a tunnel to which the shield excavator start method according to the present invention is applied.
[Explanation of symbols]
17 Tunnel body (tunnel)
30 shield excavator
40 shaft
42 Shaft construction wall
43B opening
44 Joint bracket
45 Entrance packing
49, 49 'Rebar unit (rebar)
50 concrete
51, 51 ', 51 "obstruction
55 Seal member (water-stop member)
57 Sealing material (water blocking member)
G

Claims (3)

  A method of starting a shield excavator from a shaft, wherein a shaft structure wall constituting an inner wall surface of the shaft is formed, and an opening is formed in the shaft structure wall at a position where the shield excavator is to be started. In addition, an entrance packing that closes a gap between the opening and the outer peripheral surface of the shield excavator is provided in the vicinity of the opening, and the shield excavator is started from the opening toward a natural ground. Then, while constructing the tunnel inside, it gained reaction force to the constructed tunnel and gradually advanced forward in the direction of excavation, and the rear end of the shield excavator reached the opening of the shaft structure wall Sometimes, a reinforcing bar is arranged between the opening and the outer peripheral surface of the tunnel built inside, and a concrete is placed to close a gap between the opening and the outer peripheral surface of the tunnel. These Starting method of the shield excavator, which comprises forming an occlusion to be embodied.   2. The method of starting a shield excavator according to claim 1, wherein when the shaft structure wall is formed, a joint fitting for connecting a reinforcing bar constituting the closing portion is embedded in the opening. The shield excavator starting method.   3. The shield excavator start method according to claim 1, wherein when the blocking portion is formed in a gap between the opening and the outer peripheral surface of the tunnel, water stoppage is ensured at a position in contact with the outer peripheral surface of the tunnel. A start method for a shield excavator, characterized in that a water stop member is provided.

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