JP7401391B2 - How to install rock bolts in tunnel construction - Google Patents

Description

The present invention relates to a method for installing rock bolts in tunnel construction.

In tunnel construction for mountain tunnels excavated using the NATM method, as shown in Figure 10(A), after excavating the ground, concrete C1 is placed on the inner surface 50 of the ground formed by the excavation to prevent cave-ins. be sprayed.
Thereafter, holes 52 are drilled into the inner surface 50 of the rock from above the hardened concrete C1 at multiple locations spaced apart in the circumferential and longitudinal directions of the tunnel, and a fixing material such as mortar is injected into each hole 52. Ru.
Next, a lock bolt 54 is inserted into each hole 52, and the base of the lock bolt 54 protruding from the concrete C1 is inserted into a lock bolt insertion hole 5602 of a bearing plate 56 made of a steel plate such as a square plate or a round plate. be done.
Then, this bearing plate 56 is applied to the surface of the concrete C1, a nut 58 is screwed onto the male thread at the base of the lock bolt 54, the nut 58 is fastened, and the bearing plate 56 is pressed against the surface of the concrete C1 to lock each lock. The installation work of the bolts 54 is completed, and the bedrock is fixed and stabilized.
After that, as shown in Fig. 10(B), a waterproof sheet is laid on the surface of the concrete C1 to prevent water from the ground from entering the tunnel, and the concrete is placed opposite to this waterproof sheet. A frame is placed, and concrete C2 is poured between the waterproof sheet and the formwork surface of the concrete pouring formwork to perform lining concrete.

JP2019-167774A

On the other hand, in rock bolt work, which is part of the shoring work for tunnel construction, the work of screwing the nut 58 onto the male thread at the base of the rock bolt 54, rotating the nut 58, and pressing the bearing plate 56 against the surface of the concrete C1 is performed by the worker. This is a time-consuming process, as it is often done in an awkward position as the person is placed on a scaffold.
Furthermore, since the work involves rotating the nut 58, it is time consuming and requires being near the bedrock onto which the concrete C1 has been sprayed for a long time, making the work accompanied by danger.
In particular, when the tunnel cross section is large and the tunnel length is large, the number of lock bolts 54 becomes thousands or tens of thousands, and the work of tightening the nuts 58 takes a lot of time and increases the danger. Some kind of improvement was desired from the perspective of shortening the construction period of tunnel construction and reducing costs.
The present invention was developed in view of the above circumstances, and its purpose is to omit the work of tightening nuts and to press the bearing plate onto the concrete surface with one touch, which is advantageous in reducing danger. An object of the present invention is to provide a method for installing rock bolts in tunnel construction, which is advantageous in shortening the construction period of tunnel construction and reducing costs.

In order to achieve the above-mentioned object, the present invention sprays concrete on the inner surface of the excavated rock, drills a plurality of holes in the inner surface of the rock from above the concrete, and fills the holes with a fixing material such as mortar. Insert a rock bolt into each hole, insert the base of the rock bolt protruding from the concrete into the rock bolt insertion hole of the bearing plate, and insert the bearing plate through the rock bolt onto the surface of the concrete. A method for installing a rock bolt in tunnel construction in which a mounting portion is formed at the base of the rock bolt, and the lock bolt can be attached to the mounting portion with a single touch, and the lock bolt is pressed against the mounting portion. A one-touch fixture that can be locked to the bearing plate around the bolt insertion hole is prepared, foamed concrete that expands in volume when hardened is used as the concrete, and after the foamed concrete is sprayed onto the inner surface of the ground. , drilling a plurality of holes in the inner surface of the ground from above the foamed concrete while the foamed concrete is in a semi-hardened state, injecting the fixing material into the holes, inserting the rock bolt into each hole, and The base of the rock bolt protruding from the foam concrete is inserted into the rock bolt insertion hole of the bearing plate, one side of the bearing plate is positioned on the surface of the semi-hardened foam concrete, and the other side of the bearing plate is placed on the surface of the foam concrete in a semi-hardened state. A one-touch fixing device is attached to the attachment portion of the base of the rock bolt where the side surface is located, and the one-touch fixing device prevents the bearing plate from moving away from the surface of the foamed concrete. shall be.
Further, in the present invention, the attachment portion is a through hole formed through the base of the lock bolt, and the one-touch fixing device is a cotter pin inserted into and locked in the through hole. Features.
Further, the present invention is characterized in that the mounting portion is a through hole formed through the base of the lock bolt, and the one-touch fixing device is a taper pin that is pushed into the through hole and locked. shall be.
Further, the present invention is characterized in that the mounting portion is an annular groove formed on the outer periphery of the base of the lock bolt, and the one-touch fixing device is a snap ring attached to the annular groove. shall be.
Further, the present invention is characterized in that the attachment portion is an annular groove formed on the outer periphery of the base of the lock bolt, and the one-touch fixing device is a cable tie attached to the annular groove. shall be.
Further, the present invention is characterized in that a plurality of the attachment portions are provided at intervals in the extending direction of the base portion of the lock bolt.
Further, the present invention is characterized in that a mark is provided at the base of the rock bolt, and when the rock bolt is inserted into the hole, the rock bolt is inserted until the mark is located on the surface of the foamed concrete.

According to the present invention, the conventional time-consuming work of rotating nuts can be omitted, and the one-touch work of attaching a one-touch fixture to the mounting part is sufficient, which is advantageous in improving the efficiency of lock bolt installation work. Become.
In addition, since rock bolt installation work can be done in a short time, during shoring work for tunnel construction, it is only necessary to be near the bedrock onto which concrete has been sprayed for a short time, which is advantageous in reducing danger.
In addition, since the ground can be supported in a short time, it is advantageous in stabilizing the ground quickly.
In particular, even when the tunnel cross section is large, the tunnel length is large, and the number of rock bolts is in the thousands or tens of thousands, the time required for rock bolt installation work can be significantly shortened, and tunnel construction This is advantageous in shortening the construction period and reducing costs.
In addition, cotter pins, taper pins, snap rings, and cable ties can be used as the one-touch fixing device of the present invention, and these are easily available commercially available products and are inexpensive, so they can be used to reduce the cost of tunnel construction. It will be advantageous.
In addition, in the present invention, foamed concrete that expands in volume when hardened is used as the concrete to be sprayed onto the inner surface of the ground, so even if there is a slight gap between the bearing plate and the one-touch fixing device, the rock bolt will Since the installation work can be performed easily, it is advantageous to provide a plurality of attachment parts at intervals in the extending direction of the base of the rock bolt, in order to easily perform the installation work of the rock bolt.
Additionally, by providing multiple attachment parts at intervals in the longitudinal direction of the base of the rock bolt, one rock bolt can be commonly used for holes of different depths drilled into the ground, reducing costs. This will be advantageous in terms of planning.
In addition, providing a mark on the outer circumferential surface of the base of the rock bolt makes it easier and faster to insert the rock bolt into the hole drilled on the inner surface of the ground, and is also advantageous in securing the rock bolt securely. Become.

It is a side view of the base of the rock bolt used in the rock bolt installation method of 1st Embodiment. FIG. 2 is a front view of a split pin used as a one-touch fixture in the lock bolt installation method of the first embodiment. This is an explanatory diagram of the rock bolt installation method of the first embodiment, in which the rock bolt is inserted into the drilled hole, the base of the rock bolt is inserted into the rock bolt insertion hole of the bearing plate, and the split pin is inserted into the through hole. It is a diagram with the . FIG. 4 is a view seen from the X arrow in FIG. 3, and is an explanatory diagram of a state in which the legs of the split pin are opened. It is an explanatory view of the installation method of the rock bolt of a 1st embodiment. FIG. 7 is a side view of another modification of the base of the rock bolt used in the rock bolt installation method of the first embodiment. This is an explanatory diagram of the rock bolt installation method of the second embodiment, in which the rock bolt is inserted into the drilled hole, the base of the rock bolt is inserted into the rock bolt insertion hole of the bearing plate, and the taper pin is inserted into the through hole. It is a diagram of the inserted state. This is an explanatory diagram of the lock bolt installation method of the third embodiment, in which the lock bolt is inserted into the drilled hole, the base of the rock bolt is inserted into the lock bolt insertion hole of the bearing plate, and the snap ring is inserted into the annular groove. It is a figure of the state where it is attached. This is an explanatory diagram of the lock bolt installation method of the fourth embodiment, in which the lock bolt is inserted into the drilled hole, the base of the lock bolt is inserted into the lock bolt insertion hole of the bearing plate, and a cable tie is inserted into the annular groove. It is a figure of the state where it is attached. In the explanatory diagrams of the conventional construction method, (A) is an explanatory diagram of shoring, and (B) is an explanatory diagram of lining concrete.

(First embodiment)
First, a first embodiment will be described with reference to FIGS. 1 to 5.
Note that the same reference numerals are given to the conventional parts and members, and the explanation thereof will be omitted.
As shown in FIGS. 3 and 5, in this embodiment, in tunnel construction using the NATM construction method, the concrete C1 sprayed onto the inner surface 50 of the ground formed by excavating the ground has a volume of Foamed concrete C3 which expands is used.
The expansion rate when the foamed concrete C3 expands during hardening can be adjusted by the expanding agent mixed therein.

Further, as shown in FIG. 1, a one-touch fixture 12 is attached to the base 54A of the lock bolt 54, which is the end opposite to the end to be inserted into the hole 52 drilled in the inner surface 50 of the earth. A mounting portion 14 to be mounted is provided.
The attachment portion 14 is a through hole 14A formed through the base portion 54A of the lock bolt 54.
Note that in this embodiment, since the conventional nut 58 is not used, there is no need for the base 54A of the lock bolt 54 to have a male thread. In other words, a male thread may be used as in the conventional case, or a reinforcing bar or steel bar without a male thread may be used, and in short, the attachment portion 14 may be provided on the lock bolt 54. .
As shown in FIGS. 2 and 3, the one-touch fixture 12 is a split pin 12A that is inserted into and locked in the through hole 14A.
The split pin 12A is a commercial product having a head 1202 and two legs 1204. As shown in FIG. 4, when the split pin 12A is inserted into the through hole 14A and the legs 1204 are opened, the lock bolt is removed. 54 is inserted into the lock bolt insertion hole 5602 of the bearing plate 56.
Further, as shown in FIG. 1, a mark 16 is provided on the base 54A of the rock bolt 54 to indicate how far the rock bolt 54 should be inserted into the surface of the foamed concrete C3 sprayed onto the inner surface of the earth 50. This mark 16 is provided, for example, by applying paint or by cutting.
The distance from the mark 16 to the edge of the through hole 14A on the mark 16 side is equal to the thickness of the bearing plate 56.

Next, a method for installing rock bolts 54 in tunnel construction according to the present embodiment will be explained.
As shown in FIG. 5, foamed concrete C3, which expands in volume when hardened, is sprayed onto the inner surface 50 of the earth formed by excavating the earth.
While the foamed concrete C3 is in a semi-hardened state during expansion, holes 52 are drilled into the ground from above the foamed concrete C3 at multiple locations spaced apart in the circumferential and longitudinal directions of the tunnel, and each hole 52 is filled with mortar, etc. of fixing material is injected.
Then, a lock bolt 54 is inserted into each hole 52 from above the foamed concrete C3.
In this case, as shown in FIG. 3, the rock bolt 54 is inserted until the mark 16 provided on the rock bolt 54 is located on the surface of the foamed concrete C3.
Next, the base portion 54A of the lock bolt 54 is inserted into the lock bolt insertion hole 5602 of the bearing plate 56, and one side of the bearing plate 56 is brought into contact with the surface of the semi-hardened foamed concrete C3.

Next, as shown in FIG. 3, the split pin 12A is inserted into the through hole 14A of the base 54A of the lock bolt 54 where the other side of the bearing plate 56 is located, and as shown in FIG. open.
As a result, the other side surface of the bearing plate 56 around the lock bolt insertion hole 5602 becomes capable of being engaged with the split pin 12A, and the installation of the split pin 12A is completed, and the work of installing the lock bolt 54 is also completed.
As the foamed concrete C3 expands, the bearing plate 56 tends to move away from the inner surface of the ground, but the area around the lock bolt insertion hole 5602 on the other side of the bearing plate 56 is locked by the split pin 12A. , movement of the bearing plate 56 in the direction away from the surface of the foamed concrete C3 is prevented.

Therefore, by hardening the fixing material injected into the hole 52 and the foamed concrete C3, the rock mass is fixed and stabilized by the foamed concrete C3 and the plurality of rock bolts 54.
Furthermore, even if there is a slight gap between the other side surface of the bearing plate 56 and the split pin 12A, the bearing plate 56 will be displaced away from the inner surface of the rock as the foamed concrete C3 expands, and the bearing plate 56 will be displaced away from the inner surface of the rock. The area around the lock bolt insertion hole 5602 on the other side of the plate 56 is locked by the split pin 12A, thereby preventing the bearing plate 56 from moving away from the surface of the foamed concrete C3.
Therefore, by hardening the fixing material injected into the hole 52 and the foamed concrete C3, the rock mass is fixed and stabilized by the foamed concrete C3 and the plurality of rock bolts 54.

According to this embodiment, the installation work of the lock bolt 54 can be completed by a one-touch operation of simply inserting the split pin 12A into the through hole 14A and opening the leg portion 1204.
That is, compared to the conventional work of threading the nut 58 onto the male thread of the lock bolt 54 and rotating the nut 58, the installation work of the lock bolt 54 can be completed in an extremely short time. This is advantageous in increasing the efficiency of installation work.
In addition, since the installation work of the rock bolts 54 can be carried out in a short time, it is sufficient to stay in the vicinity of the rock where the foamed concrete C3 has been sprayed for a short time, which is advantageous in reducing danger.
In addition, since the ground can be supported in a short time, it is advantageous in stabilizing the ground quickly.
In particular, according to the present embodiment, even when the tunnel cross section is large, the tunnel length is large, and the number of rock bolts 54 is in the thousands or tens of thousands, the installation work of the rock bolts 54 can be easily performed. The required time can be significantly shortened, which is advantageous in shortening the construction period of tunnel construction and reducing costs.

Note that even if there is a slight gap between the other side of the bearing plate 56 and the split pin 12A, the bearing plate 56 is prevented from moving away from the surface of the foamed concrete C3, and the lock bolt 54 is prevented from moving away from the surface of the foamed concrete C3. To facilitate installation work, as shown in FIG. 6, if a plurality of through holes 14A are provided at intervals in the extending direction of the base 54A of the lock bolt 54, the through holes near the other side surface of the bearing plate 56 By inserting the split pin 12A into the cotter pin 14A, the lock bolt 54 can be installed and the mark 16 can be omitted.
In other words, even if there is a slight gap between the other side of the bearing plate 56 and the one-touch fixture 12, the movement of the bearing plate 56 in the direction away from the surface of the foamed concrete C3 is prevented and the lock is locked. Since the bolt 54 can be installed, if a plurality of attachment parts 14 are provided at intervals in the extending direction of the base 54A of the lock bolt 54, the attachment part 14 near the other side of the bearing plate 56 can be attached with one-touch operation. By attaching the fixture 12, the lock bolt 54 can be installed easily and the mark 16 can be omitted.
Furthermore, if a plurality of attachment parts 14 are provided at intervals in the extending direction of the base 54A of the rock bolt 54, one rock bolt 54 can be commonly used for holes of different depths drilled in the ground. This is advantageous in reducing costs.
In addition, when the attachment portion 14 is formed of through holes 14A and a plurality of through holes 14A are provided, if the extending direction of the through holes 14A is shifted around the central axis of the lock bolt 54, the strength and rigidity of the lock bolt 54 are reduced. This will be advantageous in terms of securing.
The effect of providing a plurality of attachment portions 14 at intervals in the extending direction of the base portion 54A of the lock bolt 54 as described above is similarly achieved in the following embodiments.

(Second embodiment)
Next, a second embodiment will be described with reference to FIG. 7.
Note that in the following embodiments, the structure of the attachment part 14 or the structure of the one-touch fixture 12 is different from the first embodiment, and the explanation of the same parts as in the first embodiment will be omitted. The points different from the first embodiment will be explained with emphasis.
In the second embodiment, the attachment part 14 is a through hole 14B formed through the base 54A of the lock bolt 54, and the one-touch fixture 12 is a taper pin 12B that is pushed into the through hole 14B and locked. be.
The taper pin 12B is a commercially available product, and has dimensions that allow it to lock in the through hole 14B when pushed into the through hole 14B, and to lock in a location around the lock bolt insertion hole 5602 of the bearing plate 56 through which the lock bolt 54 is inserted. is used.

The method of installing the lock bolt 54 is the same as that in the first embodiment, and the lock bolt 54 is inserted into the hole 52 into which a fixing material such as mortar is injected, and the base 54A of the lock bolt 54 is locked to the bearing plate 56. The bearing plate 56 is inserted into the bolt insertion hole 5602, and one side of the bearing plate 56 is brought into contact with the surface of the semi-hardened foamed concrete C3.
Next, the taper pin 12B is pushed into the through hole 14B of the base 54A of the lock bolt 54, where the other side surface of the bearing plate 56 is located, and is locked in the through hole 14B.
As a result, the other side surface of the bearing plate 56 around the lock bolt insertion hole 5602 becomes capable of being engaged with the taper pin 12B, and the installation of the lock bolt 54 is completed at the same time as the installation of the taper pin 12B is completed.

As the foamed concrete C3 expands, the bearing plate 56 tends to move away from the inner surface of the ground, but the area around the lock bolt insertion hole 5602 on the other side of the bearing plate 56 is locked by the split pin 12A. , movement of the bearing plate 56 in the direction away from the surface of the foamed concrete C3 is prevented.
Therefore, by hardening the fixing material injected into the hole 52 and the foamed concrete C3, the rock mass is fixed and stabilized by the foamed concrete C3 and the plurality of rock bolts 54.
The second embodiment also provides the same effects as the first embodiment.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. 8.
In the third embodiment, the attachment part 14 is an annular groove 14C formed on the outer periphery of the base 54A of the lock bolt 54, and the one-touch fixture 12 is a snap ring 12C installed in the annular groove 14C. be.
The snap ring 12C is a commercially available product, and when attached to the annular groove 14C, the snap ring 12C becomes immovable in the axial direction of the base 54A of the lock bolt 54, and the lock bolt insertion hole of the bearing plate 56 into which the lock bolt 54 is inserted is inserted. A size that allows it to be locked at a location around 5602 is used.

The method of installing the lock bolt 54 is the same as that in the first embodiment, and the lock bolt 54 is inserted into the hole 52 into which a fixing material such as mortar is injected, and the base 54A of the lock bolt 54 is locked to the bearing plate 56. The bearing plate 56 is inserted into the bolt insertion hole 5602, and one side of the bearing plate 56 is brought into contact with the surface of the semi-hardened foamed concrete C3.
Next, the snap ring 12C is attached to the annular groove 14C of the base 54A of the lock bolt 54, where the other side of the bearing plate 56 is located.
As a result, the other side surface of the bearing plate 56 around the lock bolt insertion hole 5602 becomes capable of being engaged with the snap ring 12C, and the attachment of the snap ring 12C is completed, and the work of installing the lock bolt 54 is also completed.

As the foamed concrete C3 expands, the bearing plate 56 tends to move away from the inner surface of the ground, but the area around the lock bolt insertion hole 5602 on the other side of the bearing plate 56 is locked by the snap ring 12C. , movement of the bearing plate 56 in the direction away from the surface of the foamed concrete C3 is prevented.
Therefore, by hardening the fixing material injected into the hole 52 and the foamed concrete C3, the rock mass is fixed and stabilized by the foamed concrete C3 and the plurality of rock bolts 54.
The third embodiment also provides the same effects as the first embodiment.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG. 9.
In the fourth embodiment, the attachment part 14 is an annular groove 14D formed on the outer circumference of the base 54A of the lock bolt 54, and the one-touch fixture 12 is a cable tie 12D that is attached to the annular groove 14D. be.
The binding band 12D is a commercially available product, and includes a belt portion provided with teeth and a fastening head that can engage with the teeth.
A belt portion is inserted into the fastening head, and the binding band 12D is composed of a long belt 1 and a fastening head 2 integrally provided at one end of the belt 1. When installed in the annular groove 14D, the binding band 12D becomes immovable in the axial direction of the base 54A of the lock bolt 54, and in this state, the binding band 12D is locked at a location around the lock bolt insertion hole 5602 of the ring plate 56. The available dimensions are used.

The method of installing the lock bolt 54 is the same as that in the first embodiment, and the lock bolt 54 is inserted into the hole 52 into which a fixing material such as mortar is injected, and the base 54A of the lock bolt 54 is locked to the bearing plate 56. The bearing plate 56 is inserted into the bolt insertion hole 5602, and one side of the bearing plate 56 is brought into contact with the surface of the semi-hardened foamed concrete C3.
Next, the binding band 12D is attached to the annular groove 14D of the base 54A of the lock bolt 54, where the other side of the bearing plate 56 is located.
As a result, the other side surface of the bearing plate 56 around the lock bolt insertion hole 5602 becomes capable of being engaged with the binding band 12D, and the installation of the lock bolt 54 is completed at the same time as the installation of the binding band 12D is completed.

As the foamed concrete C3 expands, the bearing plate 56 tends to move away from the inner surface of the ground, but the area around the lock bolt insertion hole 5602 on the other side of the bearing plate 56 is locked by the cable tie 12D. , movement of the bearing plate 56 in the direction away from the surface of the foamed concrete C3 is prevented.
Therefore, by hardening the fixing material injected into the hole 52 and the foamed concrete C3, the rock mass is fixed and stabilized by the foamed concrete C3 and the plurality of rock bolts 54.
The fourth embodiment also provides the same effects as the first embodiment.

In the first to fourth embodiments, the case where the split pin 12A, the tapered ring 12B, the snap ring 12C, and the cable tie 12D are used as the one-touch fixture 12 has been described, but the one-touch fixture 12 is Various conventionally known one-touch fixing devices can be used without being limited to the above, and the structure of the attachment part changes depending on the one-touch fixing device to be adopted. However, if the split pin 12A, taper ring 12B, snap ring 12C, and cable tie 12D are used as the one-touch fixing device 12, they are inexpensive commercially available products and can be easily obtained, so they are effective in reducing the cost of tunnel construction. It will be advantageous.

12 One-touch fixture 1202 Head 1204 Leg 12A Cotter pin 12B Taper pin 12C Snap ring 12D Binding band 14 Attachment portion 14A, 14B Through hole 14C, 14D Annular groove 16 Marker C1, C2 Concrete 50 Earth's inner surface 52 Hole 54 Lock bolt 54A Base 56 Bearing plate 5602 Lock bolt insertion hole

Claims (7)

Spraying concrete on the inside of the excavated earth,
Drilling a plurality of holes in the inner surface of the ground from above the concrete and injecting a fixing material such as mortar into the holes,
inserting a rock bolt into each hole, inserting a base of the rock bolt protruding from the concrete into a rock bolt insertion hole of the bearing plate;
A method for installing a rock bolt in tunnel construction in which the bearing plate is pressed against the surface of the concrete via the rock bolt, the method comprising:
An attachment part is formed at the base of the lock bolt, and the one-touch can be attached to the attachment part with a single touch, and can be locked to a location of the bearing plate around the lock bolt insertion hole while being attached to the attachment part. Prepare the ceremony fixture,
Using foamed concrete that expands in volume when hardening as the concrete,
After spraying the foamed concrete onto the inner surface of the rock, in a semi-hardened state of the foamed concrete, drill a plurality of holes in the inner surface of the rock from above the foamed concrete, and inject the fixing material into these holes; inserting the lock bolt into each hole;
Inserting the base of the rock bolt protruding from the foamed concrete into the rock bolt insertion hole of the bearing plate,
One side of the bearing plate is located on the surface of the semi-hardened foamed concrete, and a one-touch fixing device is attached to the mounting portion of the base of the rock bolt where the other side of the bearing plate is located, and the one-touch type is installed. a fixture prevents movement of the bearing plate away from the surface of the foamed concrete;
A method for installing rock bolts in tunnel construction, characterized by: The attachment portion is a through hole formed through the base of the lock bolt,
The one-touch fixture is a cotter pin that is inserted into and locked in the through hole.
The method for installing rock bolts in tunnel construction according to claim 1. The attachment portion is a through hole formed through the base of the lock bolt,
The one-touch fixture is a tapered pin that is pushed into the through hole and locked.
The method for installing rock bolts in tunnel construction according to claim 1. The attachment portion is an annular groove formed on the outer periphery of the base of the lock bolt,
The one-touch fixture is a snap ring attached to the annular groove,
The method for installing rock bolts in tunnel construction according to claim 1. The attachment portion is an annular groove formed on the outer periphery of the base of the lock bolt,
The one-touch fixing device is a cable tie attached to the annular groove,
The method for installing rock bolts in tunnel construction according to claim 1. A plurality of the attachment parts are provided at intervals in the extending direction of the base of the lock bolt,
The method for installing rock bolts in tunnel construction according to any one of claims 1 to 5. A mark is provided at the base of the lock bolt,
When inserting the rock bolt into the hole, the rock bolt is inserted until the mark is located on the surface of the foamed concrete.
The method for installing rock bolts in tunnel construction according to any one of claims 1 to 5.

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