JP7461791B2 - Position adjustment jig and steel support construction method - Google Patents

Description

This invention relates to steel supports used in the primary lining of tunnels, and more specifically to a position adjustment tool that can adjust the position of installed steel supports, and a construction method using the same.

It is said that roughly two-thirds of Japan's land area is mountainous, and as a result, roads, railway tracks, etc. (hereinafter referred to as "roads, etc.") almost always have sections that pass through mountainous areas. To build roads, etc. in mountainous areas, it is common to use either the cut earth method, which excavates part of the slope, or the tunnel method, which hollows out the inside of the natural ground. While the tunnel method tends to have a higher construction cost (construction cost per length of road, etc.) than the cut earth method, it also tends to require less excavated soil (i.e., the amount of soil discharged), and has the advantage of allowing greater freedom in linear planning of roads, etc. (e.g., shortcuts can be taken), and it is said that more than 10,000 tunnels have been built in Japan to date.

Until the 1970s, the "sheet pile method," which combined steel arch supports with wooden sheet piles to support the ground, was the mainstream construction method for mountain tunnels, but now the New Australian Tunneling Method (NATM), which actively utilizes the strength of the ground, has become mainstream. NATM's main feature is its design philosophy that relies on the strength of the ground (arch effect), which makes it possible to reduce the scale of the tunnel supports compared to the conventional sheet pile method, and also to increase the construction speed, thereby reducing construction costs.

In addition, since NATM was first fully implemented in Japan, excavation technology has made great strides, and the development of various auxiliary methods has made it possible to handle a variety of natural ground, and the advancement of excavation machines (particularly open-face excavators) has made it possible to choose mechanical excavation in addition to blasting excavation. This mechanical excavation is generally adopted for natural ground with relatively low strength (for example, uniaxial compressive strength of 49 N/mm2 or ^less ), although this depends on the excavation cross-sectional area and linearity, while blasting excavation is often adopted when bedrock is present in the target natural ground.

Here, we will briefly explain the excavation procedure using NATM. First, the tunnel face is excavated. In the case of blast excavation, a drill jumbo is used to drill a hole, explosives (dynamite) are loaded, and the blasting takes place after the workers and the machine have evacuated. On the other hand, in the case of mechanical excavation, the tunnel face is cut using a free-face excavator. The excavation length (span length) of one cycle varies depending on the support pattern set according to the strength of the ground, but generally excavation is performed with a span length of 1.0 to 2.0 m. After one span length is excavated, the rubble is removed (rubbered) by a dump truck (or rail method) while "scrambling" is performed to remove unstable ground parts (loose stones, etc.). After the rubble is removed, mirror spraying or primary concrete spraying is performed, and steel supports are erected as necessary (depending on the support pattern), secondary concrete spraying is performed, and rock bolts are installed. The first and second concrete spraying and rock bolt installation will be carried out along the excavated span length, i.e., on the inner periphery of the tunnel in the unlined section (the periphery from the side walls to the top).

In this way, NATM is a construction method in which a series of processes such as rock drilling (for example, drilling holes at the tunnel face and blasting), excavation, erecting steel supports, spraying concrete, and driving rock bolts are repeated to build supports (steel supports, spraying concrete, and rock bolts) for each span, while stabilizing the ground. In other words, tunnel excavation workers (so-called miners) are required to work at the tunnel face, where the ground is not yet stable. Therefore, there is always a risk of rocks falling from the ground, such as the mirror surface or the top of the tunnel, and falling rocks, and there have been quite a few industrial accidents at the tunnel face. Therefore, in December 2016, the Ministry of Health, Labor and Welfare formulated the "Guidelines for Measures to Prevent Skin Fall Accidents at the Tunnel Face in Mountain Tunnel Construction" to encourage the promotion of industrial accident prevention measures at the tunnel face.

Among the face work, erecting steel supports is particularly dangerous for workers. Here, referring to Figure 11, the conventional steel support erection work will be explained. After rock drilling, the rock is removed and the first concrete is sprayed. As shown in Figure 11(a), a pair of left and right steel supports are installed at the designated positions on the face side, and the joint plates of the left and right steel supports are connected with bolts near the top. In addition, to connect the existing steel support (i.e., the steel support on the tunnel mouth side) to the newly installed steel support (i.e., the steel support on the face side), a tie material is also installed. This tie material is a rod-shaped member (e.g., a steel rod) with both ends bent as shown in Figure 11(b). One end of the tie material is inserted into a sheath pipe installed on the existing steel support, and the other end is inserted into a sheath pipe installed on the new steel support, thereby installing the tie material.

When bolting the joint plates and installing the ties, it is necessary to adjust the position of the steel supports. Even if a set of steel supports is installed on the left and right, the bolt hole positions of the left and right joint plates do not necessarily match, and the distance between the sheaths of the front and rear steel supports (on the tunnel mouth side and the face side) does not necessarily match the length of the ties.

When erecting the steel shoring, the bolting of the joint plates and the installation of the tie materials were mostly done manually by workers, and the adjustment of the steel shoring's installation position was also mainly done by workers. Specifically, the installation position was adjusted by digging the roadbed or back surface using a spade blind, inserting sheet piles under the back surface or bottom plate of the steel shoring, or moving the base of the steel shoring with a crowbar or the like.

When erecting steel shoring, the first concrete is sprayed, but this is merely a temporary support (temporary spraying) applied to the ground, and even though a quick-setting agent has been added, the concrete has not yet hardened sufficiently. In this environment, the bolt connection of the joint plates, the installation of the ties, and the adjustment of the installation position must be performed, making the erection of steel shoring a particularly dangerous task for workers. In other words, improving the erection work of steel shoring is an extremely effective means of preventing work-related accidents at the face.

Various technologies have been proposed to improve the efficiency and reduce the labor required for erecting steel supports. For example, Patent Document 1 proposes a technology for spraying secondary concrete while holding the steel supports with an erector.

JP 2020-26695 A

The technology disclosed in Patent Document 1 not only shortens the time required for erecting steel supports and spraying concrete, but is also expected to reduce the labor required by workers when erecting steel supports, making it ideal for preventing work-related accidents at the face.

However, in order to spray the secondary concrete while the erector is gripping the steel support, it is necessary to spray with a spray nozzle between the two erectors extending from the main body of the spraying robot toward the support, which makes spraying by passing the arm through it, making it extremely difficult in reality. In addition, it is difficult to spray the concrete reliably in areas where the gripping arm gets in the way, and there is a risk of the quality of the construction being degraded, such as the designed spray thickness not being secured in some areas. Furthermore, while the steel support was previously supported by the ground, the technology of Patent Document 1 supports the base of the steel support with sprayed concrete. However, even though a setting agent is added, it takes some time for the concrete to harden sufficiently, so there is a risk that the steel support will gradually sink and the sprayed concrete on the top and shoulders will crack.

Furthermore, in Patent Document 1, the installation of tie materials is omitted in order to shorten the work time and save the workers' labor. Since the steel shoring and the sprayed concrete are integrated, there is no need to stabilize the newly installed steel shoring with tie materials, and this means that the tie materials can be omitted. However, in addition to the function of stabilizing the newly installed steel shoring, the tie materials also have the function of installing the steel shoring at accurate intervals (i.e., ensuring the planned excavation progress length) and the function of preventing the steel shoring from twisting or opening. Therefore, according to the technology of Patent Document 1, there is a risk that the steel shoring will not be installed at accurate intervals, or that the steel shoring will be installed while twisting or opening. In other words, according to Patent Document 1, tunnel excavation will be carried out without adjusting the installation position of the steel shoring, in other words, without installing it in the appropriate position or posture.

Problems can also be pointed out regarding the adjustment of the position of the steel shoring, which is performed by workers as in conventional technology. Workers are forced to work at the face where the ground is not sufficiently stable, and it takes a considerable amount of time to adjust to the appropriate position, increasing the risk of industrial accidents due to falling rocks or falling ground. In addition, because the position of the steel shoring was adjusted (left and right and up and down) using sheet piles, the adjustment was made by a multiple of the thickness of the sheet piles, making it impossible to make delicate position adjustments.

The objective of the present invention is to solve the problems of the conventional technology, that is, to provide a position adjustment tool that can reduce the work time required for adjusting the position of steel supports compared to the conventional technology and can perform delicate position adjustments, and an installation method using the same.

The present invention was developed with a focus on the fact that the position of the steel support can be adjusted by pushing against the ground with the abutment plate and bolts, i.e., by utilizing the reaction force from the ground, and is an invention based on an unprecedented idea.

The position adjustment jig of the present invention is a position adjustment jig for adjusting the position of a steel support used in the primary lining of a tunnel, and includes an adjustment body and a projection body. The adjustment body has an attachment part that can be detachably attached to a part of the steel support, a bolt hole provided in a part of the adjustment body, and a fixing nut fixed to one opening of the bolt hole. One projection body has an insertion bolt having a thread provided on the outer periphery of a rod-shaped member, and an abutment plate attached to one end of the insertion bolt so as to be approximately perpendicular (including perpendicular) to the axis of the insertion bolt. The insertion bolt is screwed into the fixing nut. When the position adjustment jig of the present invention is attached to the leg of the steel support by the attachment part and the adjustment body is moved so as to increase the gap between the abutment plate abutting the ground and the fixing nut , the steel support moves in a direction away from the ground .

The position adjustment jig of the present invention can also include a first protrusion and a second protrusion. In this case, the adjustment body has a first bolt hole and a second bolt hole provided in a part of the adjustment body, a fixing nut fixed to one opening of the first bolt hole, and a fixing nut fixed to one opening of the second bolt hole. The first protrusion and the second protrusion have an insertion bolt having a thread on the outer periphery of a rod-shaped member, and an abutment plate attached to one end of the insertion bolt so as to be approximately perpendicular (including perpendicular) to the axis of the insertion bolt. The insertion bolt of the first protrusion is screwed into the fixing nut of the first bolt hole, and the insertion bolt of the second protrusion is screwed into the fixing nut of the second bolt hole so as to be approximately perpendicular (including perpendicular) to the insertion bolt of the first protrusion. The position adjustment jig of the present invention is attached to the leg of the steel support by the attachment part so that the insertion bolt of the first projection is approximately vertical (including vertical), and the installation position of the steel support is adjusted by moving the adjustment body up and down relative to the abutment plate of the first projection that is abutting the ground, and by moving the adjustment body left and right relative to the abutment plate of the second projection that is abutting the ground.

The position adjustment jig of the present invention can also use a "one-sided push nut" as the fixed nut. This one-sided push nut has a through hole that penetrates from the entrance to the exit, and has multiple split screws and a counter force body inside the through hole. A tapered portion that spreads toward the exit side is formed on a part of the inner peripheral wall of the through hole, and the split screw has a thread on the inner peripheral side to which the insert bolt is screwed, and an inclined portion corresponding to the tapered portion is formed on the outer peripheral side. The multiple split screws are also distributed in the circumferential direction inside the through hole, and can slide in the axial direction of the through hole with each inclined portion abutting against the tapered portion. The counter force body is an elastic body that applies an "elastic force in the entrance direction" to the split screw, and the insert bolt is screwed into the fixed nut so that the abutment plate is on the exit side. Then, when the insert bolt is pushed into the exit side with a force equal to or greater than the "elastic force in the entrance direction" by the counter force body, the split screws slide toward the exit side along the tapered portion, and each split screw moves away from the insert bolt to the outer peripheral side. After that, when the force pushing the insertion bolt toward the outlet side is released, the "elastic force in the inlet direction" from the reaction body causes the split screws to slide toward the inlet side along the tapered section and approach the insertion bolt, and each split screw screws into the insertion bolt.

The position adjustment jig of the present invention can also have an attachment section with two clamping plates. In this case, a part of the steel support is clamped between the two clamping plates, a bolt is inserted into an attachment bolt hole provided in one of the clamping plates, and the jig is detachably attached to the steel support by tightening the bolt.

The steel shoring installation method of the present invention is a method of installing a steel shoring using the position adjustment jig of the present invention, and includes a jig attachment step, a temporary installation step, and an adjustment step. In the jig attachment step, the position adjustment jig of the present invention is attached to a part of the leg of the steel shoring, and in the temporary installation step, the steel shoring is installed in a predetermined position. In the adjustment step, the installation position of the steel shoring is adjusted by the position adjustment jig attached to a part of the leg of the steel shoring in the jig attachment step .

The steel support erection method of the present invention may further include a step of removing the jig attached to a part of the leg of the steel support in the jig attachment step . In this jig removal step, the position adjustment jig is removed from the steel support after waiting for a predetermined period of time. In this case, the position adjustment jig removed in the jig removal step is used for a new jig installation work.

The position adjustment jig and steel support erection method of the present invention have the following advantages.
(1) The position of the steel support can be adjusted simply by inserting and removing the insertion bolt of the protrusion into and from the fixing nut, thereby reducing the work time required to erect the steel support, and as a result, work-related accidents at the face can be prevented.
(2) By using a "single-push nut" as the fixing nut, the position of the steel support can be adjusted simply by pushing in the insertion bolt, further shortening the erection work time.
(3) Also, since the position is adjusted by inserting and removing the insertion bolt, more delicate position adjustment can be made than with conventional sheet piles.
(4) The removable position adjustment jig can be used repeatedly, so there is no significant difference in cost compared to conventional adjustment using sheet piles.
(5) Until the sprayed concrete has sufficiently hardened, the base of the steel support is supported by the positioning fixtures (especially the projections), so that the steel support will not sink and cracks in the sprayed concrete on the top and shoulders can be avoided.

FIG. 13 is a front view showing a schematic diagram of adjusting the installation positions of a pair of left and right steel supports. (a) is a schematic perspective view showing the situation where the steel support is adjusted in the vertical direction using a position adjustment jig attached to the bottom plate, and (b) is a schematic perspective view showing the situation where the steel support is adjusted in the horizontal direction using a position adjustment jig attached to the flange. 4A is a side view showing a protrusion that constitutes a position adjustment jig, and FIG. 4B is a front view showing a contact plate of the protrusion. 4A is a side view showing an adjustment body that constitutes a position adjustment jig, and FIG. 4B is a plan view showing the adjustment body as viewed from above. 4A is a cross-sectional view showing a one-way pressing nut, FIG. 4B is a side view showing a split screw, and FIG. 4C is a front view showing the one-way pressing nut. A vertical cross-sectional view showing a position adjustment jig attached to the bottom plate of a steel support. 4A is a vertical cross-sectional view showing a position adjustment jig attached to a flange of a steel support, and FIG. 4B is a horizontal cross-sectional view showing a position adjustment jig attached to a flange of a steel support. 4A is a side view showing an adjustment body constituting a two-way position adjustment jig, and FIG. 4B is a front view showing an adjustment body constituting a two-way position adjustment jig. (a) is a vertical cross-sectional view showing a two-way position adjustment jig attached to the flange of a steel support, and (b) is a vertical cross-sectional view taken along the line CC. 1 is a flow chart showing the main steps of the steel support construction method of the present invention. FIG. 2A is a perspective view showing a steel support erected by a conventional method, and FIG. 2B is a front view showing a conventional tie member.

An example of the position adjustment jig and steel support construction method of the present invention will be explained with reference to the figures.

1. Overall Overview Figure 1 is a front view showing a schematic diagram of a situation where the installation positions of a pair of left and right steel supports AS are adjusted. As shown in this figure, the steel supports AS are made by bending H-shaped steel into a roughly semicircular shape, with a joint plate fixed to one end (top end side) and a bottom plate BP fixed to the other end (ground side). Usually, when erecting the steel supports AS, the steel supports AS are held by an erector gun or a drill jumbo, transported to the vicinity of the face, and then installed in a predetermined position. However, at this stage, the bolt hole positions of the left and right joint plates do not match, and the interval between the sheath pipes of the front and rear steel supports AS (the tunnel mouth side and the face side) is often not the same as the length of the connecting material, so the installation position is adjusted, especially around the foot of the steel supports AS, as shown by the arrows in Figure 1. The present invention relates to a position adjustment jig that can adjust the installation position of steel support work AS, and an installation method using the same.

The position adjustment jig 100 of the present invention is composed of a projection 200 and an adjustment body 300 as shown in FIG. 2. The position adjustment jig 100 attached to the foot of the steel support AS can adjust the position of the steel support AS, which is temporarily installed by an erector spraying machine or the like. For example, in FIG. 2(a), the position adjustment jig 100 is attached to a part of the bottom plate BP of the steel support AS, and the adjustment body 300 is moved relative to a part (abutment plate) of the projection 200 abutting the ground (ground) to adjust the installation height of the steel support AS. In FIG. 2(b), the position adjustment jig 100 is attached to a part of the flange of the steel support AS, and the adjustment body 300 is moved relative to a part (abutment plate) of the projection 200 abutting the ground (side wall) to adjust the installation position (horizontal position) of the steel support AS. In this way, one of the features of the position adjustment jig 100 is that it adjusts the position of the steel support AS by pressing the ground with the projection 200, in other words, by utilizing the reaction force from the ground.

2. Position Adjustment Jig Next, the position adjustment jig 100 of the present invention will be described in detail. The steel support erection method of the present invention is a method of erecting steel support AS using the position adjustment jig 100 of the present invention. Therefore, the position adjustment jig 100 of the present invention will be described first, and then the steel support erection method of the present invention will be described.

(Protruding body)
3A and 3B are diagrams showing the projection 200 constituting the position adjustment jig 100, in which (a) is a side view and (b) is a front view showing the contact plate 220 of the projection 200. As shown in FIG. 3A, the projection 200 includes an insertion bolt 210 and a contact plate 220. The insertion bolt 210 is a rod-shaped member, and a screw is provided on the entire (or part) of its outer periphery. On the other hand, the contact plate 220 is a plate-shaped member (e.g., a steel plate) as shown in FIG. 3B. Note that each corner of the contact plate 220 should be curved (so-called corner-cut) so as not to interfere with other members such as wire mesh installed behind the steel support AS.

As shown in FIG. 3, the abutment plate 220 is attached to one end of the insertion bolt 210 (the right end in the figure) so that the plate surface is approximately perpendicular (including perpendicular) to the axis of the insertion bolt 210. For example, the abutment plate 220 can be attached to the insertion bolt 210 by fixing a nut (hereinafter, for convenience, referred to as the "abutment plate nut 230") to the abutment plate 220 by welding, gluing, etc., and screwing the tip of the insertion bolt 210 into this abutment plate nut 230.

(Adjustment body)
4A and 4B are diagrams showing an adjustment body 300 constituting the position adjustment jig 100, with (a) being a side view and (b) being a plan view seen from above. As shown in Fig. 4A, the adjustment body 300 is configured to include a mounting portion 310, a bolt hole 320, and a fixing nut 330. The adjustment body 300 can be roughly divided into the mounting portion 310 and a main body portion 340, and the bolt hole 320 and the fixing nut 330 are provided in the main body portion 340.

The mounting part 310 is for mounting the adjustment body 300 to the steel support AS. For example, the mounting part 310 shown in FIG. 4 includes an upper clamping plate 311, a lower clamping plate 312, and a bolt hole (hereinafter, for convenience, referred to as the "mounting bolt hole 313"). With a part of the steel support AS, such as the bottom plate BP or a flange, inserted into the "clamping space" formed between the upper clamping plate 311 and the lower clamping plate 312, the adjustment body 300 is mounted to the steel support AS by tightening a bolt (hereinafter, for convenience, referred to as the "mounting bolt 314") inserted from the mounting bolt hole 313 provided in the upper clamping plate 311 (or the lower clamping plate 312). For this reason, it is recommended to provide a screw that screws into the mounting bolt 314 on the inner circumference of the mounting bolt hole 313, or to fix a nut to one of the openings of the mounting bolt hole 313.

In this way, the mounting part 310 has the function of removably mounting the adjustment body 300 to the steel support AS. In addition to the mounting part 310 shown in FIG. 4, various configurations of the mounting part 310 can be used as long as it can be removably attached, such as a configuration in which the adjustment body 300 is sewn to the steel support AS with bolts (in which case, bolt holes are also provided in the steel support AS) or a mounting part 310 that utilizes an electromagnet.

As shown in FIG. 4(b), the mounting portion 310 has a mounting bolt hole 313 that penetrates the upper clamping plate 311 (or the lower clamping plate 312), and one of the main body portions 340 has a bolt hole 320 that penetrates the main body portion 340. A fixing nut 330 is fixed to one opening of the bolt hole 320 (the lower opening in the figure) by welding, adhesive, or the like.

The fixing nut 330 screws into the insertion bolt 210 of the extension 200, and can be a conventional nut or a "one-side push nut 330P" as shown in FIG. 5. FIG. 5(a) is a cross-sectional view of the one-side push nut 330P, FIG. 5(b) is a side view of the split screw described below, and FIG. 5(c) is a front view of the one-side push nut 330P. Note that FIG. 5(a) shows the upper half as a cross-sectional view and the lower half as a side view, with the central axis as the boundary.

As shown in FIG. 5(a), the one-sided nut 330P is composed of a nut body BD, a split screw DV, and a reaction body RF, and this nut body BD is provided with a through hole TH that penetrates from the entrance to the exit. In addition, a tapered section TP is partially formed on the inner peripheral wall of the nut body BD that forms the through hole TH, starting from the entrance and extending partway in the direction of the central axis, so that the inner diameter of the through hole TH gradually increases toward the exit side (sloping upward in the figure).

As shown in FIG. 5(b), the split screw DV has a thread (hereinafter referred to as the "internal thread CW" for convenience) on its inner periphery that screws into the insertion bolt 210, and a slanted portion SL on its outer periphery. This slanted portion SL has a slanted shape that spreads outward toward the outlet side, and the gradient of the gradient is approximately the same as (including the same as) the gradient of the tapered portion TP. The split screw DV is able to slide (slide) in the central axis direction within the through hole TH with the slanted portion SL abutting against the tapered portion TP of the inner wall. Therefore, when the split screw DV slides toward the outlet side, it simultaneously moves toward the outer periphery, and conversely, when the split screw DV slides toward the inlet side, it simultaneously moves toward the inner periphery. A guide rail for guiding the sliding of the split screw DV can be provided on the inner periphery wall of the nut body BD, and this guide rail can also be formed in a spiral shape.

As shown in FIG. 5(c), multiple split screws DV (three in the figure) are housed in the through hole TH, and these multiple split screws DV are distributed around the circumference of the through hole TH. For example, in the case of housing three split screws DV as shown in the figure, it is recommended to distribute them at intervals so that the central angle is 120°.

The reaction body RF is an elastic body such as a spring or synthetic resin (such as rubber), and FIG. 5(a) shows a coil spring that coils along the inner peripheral wall of the nut body BD. A fixed plate FX is attached to the outer periphery of the through hole TH near the outlet by welding, gluing, crimping, or the like. The outlet end of the reaction body RF is fixed to this fixed plate FX, and a support plate HL is attached to the inlet end of the reaction body RF. Since the fixed plate FX cannot move within the through hole TH, the outlet end of the reaction body RF cannot move within the through hole TH either. On the other hand, the support plate HL is attached only to the inlet end of the reaction body RF, and can move within the through hole TH as the reaction body RF expands and contracts. In other words, the inlet side of this reaction body RF is the movable end, and the outlet side is the fixed end.

The support plate HL attached to the inlet end of the reaction body RF abuts against the outlet side of the split screw DV. The support plate HL has a range of motion that is generally within the section of the inner wall of the nut body BD where the tapered section TP is not formed (hereinafter referred to as the "straight wall section"), and the reaction body RF is positioned so that it is in a compressed state (i.e., a state in which it is shorter than its natural length) when the support plate HL is located at the boundary between the tapered section TP and the straight wall section. As a result, the split screw DV is constantly subjected to an elastic force in the inlet direction (hereinafter referred to as the "restoring force" for convenience) from the reaction body RF via the support plate HL.

Below, an example of using the one-way push nut 330P will be described. For example, the insert bolt 210 is inserted from the entrance of the one-way push nut 330P, and the insert bolt 210 is pushed toward the exit side with a force equal to or greater than the restoring force of the reaction body RF. As a result, the multiple split screws DV slide toward the exit side and move toward the outer periphery away from the insert bolt 210. Therefore, the outer peripheral thread of the insert bolt 210 and the inner peripheral thread CW of the split screw DV do not screw together, and the insert bolt 210 can be easily passed through the one-way push nut 330P. In other words, the thread on the insert bolt 210 side overcomes the thread on the split screw DV side, so that the insert bolt 210 can be passed through the one-way push nut 330P simply by pushing it in without rotating (threading) the insert bolt 210 around the axis.

When the insertion bolt 210 is inserted into the one-sided push nut 330P to a predetermined position, the force pushing the insertion bolt 210 is released. As a result, the multiple split screws DV slide toward the entrance side due to the restoring force of the reaction force RF, and move toward the inner circumference so as to approach the insertion bolt 210. As a result, the outer thread of the insertion bolt 210 and the inner thread CW of the split screws DV screw together, making it impossible to pull out the insertion bolt 210 in the entrance direction. However, even in this state, the insertion bolt 210 can be pulled out in the entrance direction by rotating it around the axis like a conventional bolt and nut, and the insertion bolt 210 can be pulled out of the one-sided push nut 330P by pushing the insertion bolt 210 in the exit direction.

(Installation of extensions)
The insertion bolt 210 is screwed into the fixing nut 330, whereby the projection 200 is attached to the adjustment body 300, thereby forming the position adjustment jig 100 of the present invention. However, when a one-sided pushing nut 330P is used as the fixing nut 330, it is preferable to screw the insertion bolt 210 into the one-sided pushing nut 330P so that the abutment plate 220 is on the outlet side of the through hole TH.

(Example of use)
6 is a vertical cross-sectional view showing the position adjustment jig 100 attached to the bottom plate BP of the steel support AS. In this figure, a part of the bottom plate BP is inserted between the upper clamping plate 311 and the lower clamping plate 312 (clamping space), and in this state, the mounting bolt 314 is screwed in to press the bottom plate BP against the lower clamping plate 312. In other words, the position adjustment jig 100 is attached by clamping the bottom plate BP between the mounting bolt 314 and the lower clamping plate 312. Of course, the position adjustment jig 100 can be easily removed from the bottom plate BP by loosening the mounting bolt 314.

As shown in Fig. 6, when the position adjustment jig 100 is attached to the bottom plate BP and the abutment plate 220 is grounded (abutted) on the ground (ground), the protruding length of the insert bolt 210 from the fixing nut 330 is extended. At this time, when a normal nut is used as the fixing nut 330, the insert bolt 210 is rotated around the axis (i.e., screwed in), and when a one-sided pressing nut 330P is used as the fixing nut 330, the insert bolt 210 is pushed downward with a force equal to or greater than the restoring force of the reaction body RF. As a result, the protruding length of the insert bolt 210 from the fixing nut 330 is extended, in other words, the gap between the abutment plate 220 and the fixing nut 330 is widened, and the adjustment body 300 rises and the steel support AS also rises. In this way, by using the position adjustment jig 100, the installation height of the steel support AS can be easily adjusted.

Figure 7 shows the position adjustment jig 100 attached to the flange of the steel support AS, where (a) is a vertical cross-sectional view and (b) is a horizontal cross-sectional view (shown by arrow a-a in (a)). In this figure, a part of the flange is inserted between the upper clamping plate 311 and the lower clamping plate 312 (clamping space), and in this state the mounting bolt 314 is screwed in to press the flange against the lower clamping plate 312. In other words, the position adjustment jig 100 is attached by clamping the flange between the mounting bolt 314 and the lower clamping plate 312. Of course, the position adjustment jig 100 can be easily removed from the flange by loosening the mounting bolt 314.

As shown in FIG. 7, when the position adjustment jig 100 is attached to the flange and the abutment plate 220 is grounded (abutted) against the ground (side wall), the protruding length of the insert bolt 210 from the fixing nut 330 is extended. At this time, when a normal nut is used as the fixing nut 330, the insert bolt 210 is rotated around the axis (i.e., screwed in), and when a one-sided nut 330P is used as the fixing nut 330 , the insert bolt 210 is pushed downward with a force equal to or greater than the restoring force of the reaction body RF. As a result, the protruding length of the insert bolt 210 from the fixing nut 330 is extended, in other words, the gap between the abutment plate 220 and the fixing nut 330 is widened, and the adjustment body 300 moves toward the inner space (toward the tunnel center) and the steel support AS also moves toward the inner space. In this way, by using the position adjustment jig 100, the installation position (horizontal position) of the steel support AS can be easily adjusted.

(Modification)
The position adjustment jig 100 described so far can adjust the installation height of the steel support AS as shown in Fig. 6, and can adjust the installation position in the left-right direction as shown in Fig. 7. That is, in order to adjust the steel support AS in both height and left-right directions, the first position adjustment jig 100 is attached to the bottom plate BP of the steel support AS, and the second position adjustment jig 100 is further attached to the flange of the steel support AS (that is, two position adjustment jigs 100 are attached). On the other hand, if a position adjustment jig 100 equipped with a first protruding body and a second protruding body (hereinafter referred to as a "two-way position adjustment jig 100") is attached, the height and left-right directions can be adjusted simultaneously.

8 is a diagram showing an adjustment body 300 (hereinafter referred to as "two-way adjustment body 300") constituting a two-way position adjustment jig 100, (a) is a side view, and (b) is a front view (indicated by arrow b-b in (a)) seen from the main body part 340 side (right side of FIG. 8(a)). As shown in FIG. 8, the two-way adjustment body 300 is composed of an attachment part 310, a first bolt hole 321 and a second bolt hole 322, a first fixing nut 331 and a second fixing nut 332. The two-way adjustment body 300 also has a vertical wall body 350 that is erected approximately vertically (including vertically) on the upper surface of the main body part 340 side, and the second bolt hole 322 is provided so as to penetrate this vertical wall body 350, and the second fixing nut 332 is fixed to one opening of this second bolt hole 322 (the right opening in FIG. 8(b)) by welding, adhesive, etc. Apart from the inclusion of the vertical wall body 350, the second bolt hole 322, and the second fixing nut 332, the other configurations are the same as those of the adjustment body 300 shown in FIG. 4. In addition, the first fixing nut 331 and the second fixing nut 332 can be normal nuts or one-sided pressing nuts 330P.

As described above, the two-way position adjustment jig 100 includes a first protruding body and a second protruding body. These first protruding body and second protruding body have the same configuration as the protruding body 200 shown in FIG. 3, that is, the first protruding body includes a first insertion bolt 211 and a first abutment plate 221, and the second protruding body includes a second insertion bolt 212 and a second abutment plate 222. The first insertion bolt 211 is screwed into the first fixing nut 331, and the second insertion bolt 212 is screwed into the second fixing nut 332, thereby forming the two-way position adjustment jig 100. In this case, when using the one-sided nut 330P, it is preferable to screw the first insertion bolt 211 and the second insertion bolt 212 into the one-sided nut 330P so that the first abutment plate 221 and the second abutment plate 222 are on the exit side of the through hole TH.

As can be seen from FIG. 8(b), the vertical wall body 350 is erected substantially perpendicular (including perpendicular) to the upper surface of the main body portion 340, so the central axis of the first bolt hole 321 and the central axis of the second bolt hole 322 are also substantially perpendicular (including perpendicular). Therefore, the axial direction of the first insertion bolt 211 screwed into the first bolt hole 321 and the axial direction of the second insertion bolt 212 screwed into the second bolt hole 322 are also substantially perpendicular (including perpendicular).

9 shows a two-way position adjustment jig 100 attached to the bottom plate BP of the steel support AS, where (a) is a vertical cross-sectional view, and (b) is a vertical cross-sectional view taken along the arrows c-c in (a). In this figure, a part of the bottom plate BP is inserted between the upper clamping plate 311 and the lower clamping plate 312 (clamping space), and the bottom plate BP is pressed against the lower clamping plate 312 by screwing in the mounting bolt 314 in this state. In other words, the position adjustment jig 100 is attached by clamping the bottom plate BP between the insertion bolt 210 and the lower clamping plate 312. Of course, the position adjustment jig 100 can be easily removed from the bottom plate BP by loosening the mounting bolt 314.

9, the two-way position adjustment jig 100 is attached to the bottom plate BP with the first insertion bolt 211 in a substantially vertical (including vertical) position and the second insertion bolt 212 in a substantially horizontal (including horizontal) position, and the first abutment plate 221 is in contact with the ground (foundation) and the second abutment plate 222 is in contact with the ground (side wall). In this state, when the protruding length of the first insertion bolt 211 from the first fixing nut 331 is extended, the distance between the first abutment plate 221 and the first fixing nut 331 increases, and the two-way adjustment body 300 rises and the steel support AS also rises. In addition, when the protruding length of the second insertion bolt 212 from the second fixed nut 332 is increased, the distance between the second abutment plate 222 and the second fixed nut 332 increases, and the two-way adjustment body 300 moves toward the inner space (toward the center of the tunnel) and the steel support AS also moves toward the inner space. In this way, by using the two-way position adjustment jig 100, the installation height and horizontal position of the steel support AS can be easily and simultaneously adjusted.

3. Steel shoring erection method Next, the steel shoring erection method of the present invention will be described with reference to Figure 10. The steel shoring erection method of the present invention is a method for erecting steel shoring AS using the position adjustment jig 100 described so far. Therefore, we will avoid any overlapping description with the description of the position adjustment jig 100, and only describe the content unique to the steel shoring erection method of the present invention. In other words, the content not described here is the same as that described in "2. Position adjustment jig".

Figure 10 is a flow diagram showing the main steps of the steel support construction method of the present invention. First, a position adjustment jig 100 is attached to the bottom plate BP and web of the steel support AS (Step 10). At this time, the position adjustment jig 100 may be attached to both the bottom plate BP and the web, or the position adjustment jig 100 may be attached to either the bottom plate BP or the web, or a two-way position adjustment jig 100 may be attached to the bottom plate BP.

When the position adjustment jig 100 is attached to the legs of the steel support AS (bottom plate BP or web), the steel support AS with the position adjustment jig 100 attached is temporarily installed (Step 20). Depending on the construction situation, the position adjustment jig 100 can be attached to the legs of the steel support AS (Step 10) after the steel support AS is temporarily installed (Step 20). However, in this case, the work (attachment work) near the face will increase, so the procedure shown in Figure 10 is preferable.

Once the steel support AS has been provisionally installed, the abutment plate 220 is placed in contact with the ground as shown in Figures 6, 7, and 9, and the installation height and horizontal position of the steel support AS are adjusted while extending the protruding length of the mounting bolt 314 from the fixing nut 330 as described above (Step 30).

After that, when waiting until the sprayed concrete has developed a sufficient degree of strength, the position adjustment jig 100 attached to the steel support AS is removed (Step 40), and the position adjustment jig 100 is attached to the legs of the new steel support AS to be erected (Step 10). For example, the position adjustment jig 100 can be removed when a predetermined number of excavation cycles (e.g., 2 to 3 cycles) have progressed, and reused when erecting the next excavation cycle.

The position adjustment jig and steel support construction method of the present invention can be used in various tunnel excavation works, such as road tunnels, railway tunnels, and pedestrian tunnels. The present invention can shorten the working time at the tunnel face, which will lead to the prevention of industrial accidents. This invention is not only applicable to industry, but is also expected to make a great contribution to society.

100 Position adjustment jig of the present invention 200 Extension body (of position adjustment jig) 210 Insertion bolt (of extension body) 211 First insertion bolt (of extension body) 212 Second insertion bolt (of extension body) 220 Abutment plate (of extension body) 221 First abutment plate (of first extension body) 222 Second abutment plate (of second extension body) 230 Abutment plate nut (of extension body) 300 Adjustment body (of position adjustment jig) 310 Mounting part (of adjustment body) 311 Upper clamping plate (of mounting part) 312 Lower clamping plate (of mounting part) 313 Mounting bolt hole (of mounting part) 314 Mounting bolt (of mounting part) 320 Bolt hole (of adjustment body) 321 First bolt hole (of two-way adjustment body) 322 Second bolt hole (of two-way adjustment body) 330 Fixed nut (of adjusting body) 331 First fixed nut (of two-way adjusting body) 332 Second fixed nut (of two-way adjusting body) 340 Main body (of adjusting body) 350 Vertical wall body (of two-way adjusting body) 330P One-way pushing nut BD Nut body (of one-way pushing nut) TH Through hole (of one-way pushing nut) TP Tapered portion (of one-way pushing nut) DV Split screw (of one-way pushing nut) CW Inner thread (of split screw) SL Inclined portion (of split screw) RF Reaction body (of one-way pushing nut) FX Fixed plate (of one-way pushing nut) HL Support plate (of one-way pushing nut) AS Steel support BP Bottom plate (of steel support)

Claims (6)

A position adjustment jig for adjusting the position of a steel support used in the primary lining of a tunnel,
The device includes an adjustment body and a projection body,
The adjustment body has an attachment portion that can be detachably attached to a part of the steel support, a bolt hole provided in a part of the adjustment body, and a fixing nut fixed to one opening of the bolt hole,
The protrusion includes an insertion bolt having a screw threaded on the outer periphery of a rod-shaped member, and a contact plate attached to one end of the insertion bolt so as to be perpendicular or approximately perpendicular to the axis of the insertion bolt.
The insertion bolt is screwed into the fixing nut,
The adjustment body is attached to the leg of the steel support by the attachment part, and when the adjustment body is moved so as to widen the gap between the abutment plate abutting the ground and the fixing nut , the steel support moves in a direction away from the ground .
A position adjustment jig characterized by: A position adjustment jig for adjusting the position of a steel support used in the primary lining of a tunnel,
The vehicle is provided with an adjustment body, a first extension body, and a second extension body,
The adjustment body has an attachment portion that can be detachably attached to a portion of the steel support, a first bolt hole and a second bolt hole provided in a portion of the adjustment body, a fixing nut fixed to one opening of the first bolt hole, and a fixing nut fixed to one opening of the second bolt hole,
The first protrusion and the second protrusion each include an insertion bolt having a screw threaded on an outer periphery of a rod-shaped member, and an abutment plate attached to one end of the insertion bolt so as to be perpendicular or approximately perpendicular to an axis of the insertion bolt,
The insertion bolt of the first overhang is screwed into the fixing nut of the first bolt hole, and the insertion bolt of the second overhang is screwed into the fixing nut of the second bolt hole so as to be perpendicular or approximately perpendicular to the insertion bolt of the first overhang,
The first projection is attached to the leg of the steel support by the mounting portion so that the insertion bolt of the first projection is vertical or approximately vertical, and the installation position of the steel support can be adjusted by moving the adjustment body up and down relative to the abutment plate of the first projection that is abutting against the ground, and by moving the adjustment body left and right relative to the abutment plate of the second projection that is abutting against the ground.
A position adjustment jig characterized by: The fixing nut has a through hole extending from an inlet to an outlet, and has a plurality of split screws and a reaction body within the through hole,
A tapered portion that widens toward the outlet side is formed on a part of an inner peripheral wall of the through hole,
The split screw has a thread on an inner periphery side into which the insertion bolt is screwed, and an inclined portion corresponding to the tapered portion is formed on an outer periphery side,
The split screws are arranged in a circumferential direction within the through hole in a dispersed manner, and are each slidable in the axial direction of the through hole with the inclined portion in contact with the tapered portion,
The reaction body is an elastic body that applies an elastic force in an inlet direction to the split screw,
The insertion bolt is screwed into the fixing nut so that the abutment plate is on the outlet side,
When the insertion bolt is pushed toward the outlet side with a force equal to or greater than the elastic force of the reaction body in the inlet direction, the split screws slide toward the outlet side along the tapered portion, and each of the split screws separates from the insertion bolt toward the outer periphery,
When the force pushing the insertion bolt toward the outlet side is released, the split screws slide toward the inlet side along the tapered portion due to the elastic force of the reaction body in the inlet direction, and each of the split screws screws into the insertion bolt.
3. The position adjustment jig according to claim 1 or 2. The mounting portion has two clamping plates, one of which is provided with a mounting bolt hole,
The steel support can be detachably attached to the steel support by clamping a part of the steel support with the two clamping plates and tightening the bolt inserted into the mounting bolt hole.
4. The position adjustment jig according to claim 1, wherein the position adjustment jig is a position adjustment tool. A jig mounting process for mounting the position adjustment jig according to any one of claims 1 to 4 to a part of a leg of a steel support for a primary tunnel lining;
A temporary installation process of installing the steel support in a predetermined position;
an adjustment step of adjusting the installation position of the steel support by the position adjustment jig attached to a part of the leg of the steel support in the jig attachment step ;
A steel support construction method comprising: Further provided is a jig removal process for removing the position adjustment jig attached to a part of the leg of the steel support in the jig attachment process from the steel support after waiting for a predetermined period of time after the adjustment process,
The position adjustment jig removed in the jig removal step is used in a new jig installation step.
The steel support erection method according to claim 5.

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