JP2001349196A - Method for installing rock bolt and its auxiliary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for installing a rock bolt, by which the upward rock bolt can be fully bounded completely or approximately and which has even excellent profitability, and an auxiliary tool proper to installation in a full-bounded rock bolt construction method. SOLUTION: A push-up fitting 3 is installed at the front end section of the rock bolt 1, a mortar supporting valve 2 to the lower section of the push-up fitting and a mortar falling preventive valve 4 at the lower end of the mortar supporting valve. A mortar injection pipe 8 is inserted up to the front end of a previously bored rock bolt hole (a), and pulled down, injecting mortar 9. The quantity of mortar injected is decided in quantity, in which the rock bolt hole (a) is filled with mortar 9 after the insertion of the rock bolt 1. The rock bolt 1 is inserted into the rock bolt hole (a). Mortar 9 is pushed up by the push-up fitting 3, and partially lowering mortar 9 is received by the mortar supporting valve 2. The mortar supporting valve 2 is moved to the lower section of the rock bolt 1 in response to the lowering of mortar 9. The mortar falling preventive valve 4 is stopped in a hole port, and prevents the falling of mortar 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying an adhesive lock bolt used in the NATM method or the like and an auxiliary tool used for the method.

[0002]

2. Description of the Related Art Conventional types of adhesive lock bolts include a full adhesive lock bolt, an injection lock bolt, and a tip fixing capsule type.

[0003] Among these, the injection type lock bolt is a method in which a lock bolt and an injection pipe and an exhaust pipe are simultaneously inserted into a pre-drilled lock bolt hole and mortar is filled from the injection pipe, or a hollow lock is inserted into the lock bolt hole. This method inserts bolts and injects mortar from the discharge holes provided in the lock bolts.However, it takes a long time to install, and if the wall surface of the lock bolt holes is rough, it is necessary to insert the injection pipe and exhaust pipe. It is not generally used for reasons such as difficulty and high cost.

Further, in the tip fixing capsule method, a capsule or the like containing a flash-setting fixing material such as a resin is inserted into the tip of a pre-drilled lock bolt hole, and then mortar is injected and a lock bolt is inserted. This is a method in which the tip of the lock bolt is bonded to the ground by piercing the capsule. However, since the fixing material capsule is expensive, it is not generally used except in special cases such as a large amount of groundwater.

[0005] For this reason, in the lock bolt construction in tunnel construction by the NATM method, in general, a full-adhesion type lock bolt using mortar as a fixing material is used.

[0006]

SUMMARY OF THE INVENTION As described above, NAT
In the case of rock bolt construction in tunnel construction by the M construction method, a full-adhesion type lock bolt is generally used, but in the case of upward installation from the shoulder of the tunnel to the top end, the mortar drops when inserting the lock bolt, It is pointed out that a case near the tip of the lock bolt is not fixed.

In the conventional quality control of a lock bolt, there is no effective means for examining the above situation, and only evaluation is made as to whether or not the pull-out strength satisfies a predetermined value. However, with the increase in length of the lock bolts accompanying the enlargement of the tunnel cross section, it has become necessary to ensure an appropriate ground improvement width.

Further, the development of a non-destructive inspection method for inspecting the lock bolt length after the construction has been advanced, and it is considered that items relating to the lock bolt length and the fixing length will be important as quality control items in the future.

The present invention has been developed in view of the above-mentioned background. In the full-adhesion type lock bolt method, the upward lock bolt can be completely or almost completely adhered, and economical efficiency can be improved. An object of the present invention is to provide an excellent rock bolt construction method and an auxiliary tool suitable for the construction.

[0010]

According to a first aspect of the present invention, a lock material is filled in a lock bolt hole, a lock bolt is inserted, and the lock bolt is fixed by hardening the hard material. In the method of installing a lock bolt for, a disk-shaped hardened material support valve having an outer diameter substantially equivalent to the diameter of the lock bolt hole on the outer periphery of the lock bolt in advance,
The lock bolt is mounted so as to be movable in the axial direction, and the flow of the hardening material when the lock bolt is inserted is suppressed by the hardening material support valve.

As the hardening material, mortar is mainly considered in terms of ease of handling and cost, but various mortars can be used, and hardening materials other than mortar may be used.

Normally, the hardening material is filled into the lock bolt hole by an injection pipe or the like prior to the insertion of the lock bolt. For example, a part of the tip portion is replaced with a pack filled with the hardening material such as a mortar pack. By employing a method in which the pack is pierced by inserting the lock bolt, the filling state of the hardening material at the tip of the lock bolt hole can be made more reliable.

As a lock bolt, a diameter of 22 to 29 m
m shaped bars (including twisted bars, fully threaded bars, etc.) are common, and commercially available bars can be used. The length of the lock bolt differs depending on the ground condition, the tunnel diameter, and the like, and is generally about 2 to 6 m. However, the present invention is particularly effective when the lock bolt is long.
The lock bolt hole into which the lock bolt is inserted is generally about 34 to 42 mm.

The above is a list of conventional materials and numerical values, and the present invention is often applied within the above range, but is not necessarily limited thereto.

[0015] The hardened material support valve is such that, when mounted on the outer periphery of the lock bolt, the space between the lock bolt and the lock bolt hole is substantially closed in the axial direction of the lock bolt. When the bolt is inserted, the hardening material such as mortar is prevented from flowing in the hole direction.

However, the original purpose is to prevent a gap from being formed at the tip of the lock bolt hole due to the flow of the hardening material, and the lock bolt is moved in the axial direction of the lock bolt by resistance from the hardening material. Of the lock bolt hole reaches the tip of the lock bolt hole.

In a state where the outer periphery of the hardening material support valve and the lock bolt are in close contact with each other, the flow of the hardening material can be suppressed and the interference with the lock bolt hole wall is small. It is desirable to use a material having flexibility, but it is not particularly limited as long as it can be attached to the outer periphery of the lock bolt and can move in the axial direction of the lock bolt while suppressing the mortar from flowing down. For example, it may be made of synthetic resin or metal.

According to a second aspect of the present invention, in the method for installing a lock bolt according to the first aspect, a hardening material push-up metal fitting having a plurality of legs extending in a radial direction of the lock bolt hole is provided. One or more mounting members are mounted above the material support valve, and the hard bolt filled in the lock bolt hole is pushed up by the legs, and the lock bolt is inserted.

The hardening material push-up metal fitting is attached to the outer periphery of the lock bolt, and when the lock bolt is inserted into the lock bolt hole, the hard material such as mortar is pushed up by its legs,
It has a function of preventing a gap from being formed at the tip portion of the lock bolt hole, and a function of preventing the lock bolt from dropping due to resistance of the legs in the hardening material.

Heretofore, as this kind of hardening material pushing-up fitting, there has been known one having a mounting portion to a lock bolt and a plurality of legs.

According to a third aspect of the present invention, there is provided the lock bolt installation method according to the first or second aspect, wherein a hardened material fall prevention valve having a lock bolt insertion port for inserting the lock bolt and an air vent hole is provided on the outer periphery of the lock bolt. Is mounted below the hardening material support valve, and when the lock bolt is inserted, the hardening material support valve closes the hole of the lock bolt hole to prevent the hardening material from dropping.

The hardening material drop prevention valve is for preventing the hardening material from leaking out at the hole of the lock bolt hole. When the valve is stopped in the hole, the lock bolt is pushed from the lock bolt insertion hole. Can be. Further, it is necessary to release an amount of air or hardening material corresponding to the volume of the inserted lock bolt, and an air vent hole is provided for this.

This hardened material fall prevention valve has some features in common with the mouth packer used in the conventional post-injection system in terms of function. However, the conventional mouth packer has a lock bolt insertion port, an air vent hole, and the like. Although the mortar inlet is provided, the hardening material is basically injected first in the present invention, and thus the hardening material drop prevention valve is not provided with the hardening material inlet.

The hardened material support valve according to claim 4 of the present application can be used directly in the construction method according to claims 1 to 3, and has an outer diameter substantially equivalent to the diameter of the lock bolt hole. It is made of a disk-shaped member, and has a lock bolt insertion portion for inserting the lock bolt in the center portion, and can be moved in the axial direction of the lock bolt while being attached to the outer periphery of the lock bolt. .

According to a fifth aspect of the present invention, there is provided the hardening material support valve according to the fourth aspect, wherein the disc-shaped member is made of rubber, and a plurality of cuts are provided at a central portion so that a lock bolt can be inserted. is there.

As described in relation to the first aspect, in the case of a rubber-made hardened material support valve, it has elasticity and flexibility so that the hardened material can flow down while being in close contact with the outer periphery of the lock bolt. It can be suppressed, and even if it collides with the hole wall of the lock bolt hole, it is elastically deformed, and there is no danger that it stops at a specific place during the insertion of the lock bolt and stops functioning.

Further, by forming a cut in the central portion as in claim 5, the lock bolt insertion portion can be easily formed, and when the lock bolt is inserted into the lock bolt hole, a hardening material is used. It can be moved along the lock bolt by the resistance received.

According to a sixth aspect of the present invention, there is provided a hardening material pushing-up metal fitting, comprising: a mounting portion for mounting on an outer periphery of a lock bolt; and a plurality of legs extending radially outward from the mounting portion from the mounting portion. An enlarged portion is provided at the tip of the leg.

By providing the enlarged portion, the closing ratio of the lock bolt hole to the cross section is increased, and the pushing-up effect is enhanced.

According to a seventh aspect of the present invention, in the hardening material push-up metal fitting according to the sixth aspect, the leg portion extends obliquely in a direction opposite to a direction in which the lock bolt is inserted into the lock bolt hole, and is radially outwardly provided by a spring. This limits the case in which it is energized.

The shape which spreads obliquely in the direction opposite to the direction of insertion into the lock bolt hole facilitates insertion,
By urging the lock bolt radially outward with a spring, a gap is not formed between the lock bolt hole and the case where the hole diameter is different or the hole diameter is not constant can be dealt with. .

The spring may be a leaf spring itself, or may be a spring in which a spring is separately provided at the base of the leg.

The hardened material fall prevention valve according to claim 8 of the present application is formed of a truncated conical member having a maximum diameter larger than the lock bolt hole and a minimum diameter smaller than the lock bolt hole. A lock bolt insertion hole for allowing the lock bolt to be inserted movably in the axial direction, and one or a plurality of air vent holes are provided radially outside the lock bolt insertion hole.

As described above, this hardened material fall prevention valve is
With the hardening material injected and filled in the lock bolt hole, while the air escapes at the hole, the hardening material leaks along with the hardening material fall prevention valve and hardening material push-up metal fitting located above,
It has a function of preventing a gap from being formed at the tip of the lock bolt hole.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a method for installing a lock bolt according to claims 1 to 3 of the present application, and works according to the following procedure.

[Procedure 1] Push-up fitting 3 on lock bolt 1
Then, the mortar support valve 2 and the mortar fall prevention valve 4 are mounted (see FIG. 1A). When mounting the push-up fitting 3 only in one stage, it is mounted on the head of the lock bolt 1. In the case of mounting in two steps, as shown in FIG. The mortar support valve 2 is mounted below the push-up fitting 3. The mortar fall prevention valve 4 is attached to the lower part of the bolt, and stops at the hole of the lock bolt hole a during construction.

[Procedure 2] Insert the mortar injection tube 8 to the end of the previously drilled lock bolt hole a,
While injecting (see FIG. 1 (b)). The mortar injection amount is an amount that the mortar 9 fills the lock bolt hole a after the lock bolt 1 is inserted.

[Procedure 3] The lock bolt 1 is inserted into the lock bolt hole a (see FIG. 1C). The mortar 9 is partially pushed down while being pushed up by the push-up fitting 3. At this time, the mortar support valve 2 moves below the lock bolt 1 as the mortar 9 descends. The mortar fall prevention valve 4 stops at the hole (see FIG. 1 (d)).

FIG. 3 shows an embodiment of the hardening material pushing-up fitting 3 according to the sixth and seventh aspects. Push-up bracket 3
Conventionally, a member having a cylindrical mounting portion 3a and a plurality of legs 3b has been used. In this example, an enlarged portion 3c is formed at the tip of the leg 3b, so that the mortar is pressed. The effect of raising is increasing.

The leg 3b is made of a spring steel material.
As shown in (c), when the lock bolt 1 is opened in a direction opposite to the insertion direction, the distal end portion where the enlarged portion 3c is formed comes into contact with the hole wall of the lock bolt hole a.

That is, when the push-up fitting 3 is inserted into the lock bolt hole a, the leg 3b is narrowed, the mortar 9 is pushed up at the closed portion, and excess mortar is discharged from the opening. In addition, in the conventional thing, since the closing area when inserting the lock bolt 1 into the lock bolt hole a is small, the mortar pushing-up effect is small.

FIG. 4 shows an embodiment of the hardened material support valve according to the fourth and fifth aspects. The mortar support valve 2 shown here is made of a disc-shaped hard rubber or the like having a thickness of about 3 mm, and the lock bolt 1 can be inserted into that portion by making a cut 2a in the center.

The mortar support valve 2 gradually moves below the lock bolt 1 by the weight of the mortar while receiving the mortar that has descended. However, since the mortar support valve 2 has elasticity, the lock bolt hole a is not completely closed, so that air and mortar can move from the periphery of the support valve 2 and the lock bolt 1 insertion portion.

FIG. 5 shows an embodiment of the hardened material fall prevention valve according to claim 8. The fall prevention valve 4 is of the same type as the mouth packer used in the post-injection system, but the conventional mouth packer has a bolt insertion port, a mortar injection port, and an air vent port. Since the fall prevention valve 4 of the present invention is not intended for post injection, it is constituted only by the bolt insertion port 4a and the air vent 4b. Suitable material is hard rubber or the like.

The fall prevention valve 4 is connected to the lock bolt 1
The main purpose is to prevent excess mortar from dropping when the lock bolt 1 is inserted, rather than filling the mortar into the tip portion, and to densely fill the mortar. Therefore, if the mortar injection amount is properly managed, the fall prevention valve 4 is not necessarily required as a method of applying the lock bolt 1.

FIG. 6 shows a case where a mortar pack is used as another embodiment of the method of installing a lock bolt according to claims 1 to 3 of the present application. The operation is performed in the following procedure.

[Procedure 1] Push-up fitting 3 on lock bolt 1
Then, the mortar support valve 2 and the mortar fall prevention valve 4 are mounted (see FIG. 1A). When mounting the push-up fitting 3 only in one stage, it is mounted on the head of the lock bolt 1. When mounting in two stages, for example, as shown in FIG. The mortar support valve 2 is mounted below the push-up fitting 3. The mortar fall prevention valve 4 is attached to a lower portion of the lock bolt 1 so that the mortar fall prevention valve 4 stops at the hole of the lock bolt hole a during the construction.

[Procedure 2] The mortar pack 7 is pushed up together with the fixing metal 7a by the mortar injection pipe 8 into the previously drilled lock bolt hole a (see FIG. 6B).

[Procedure 3] The mortar injection pipe 8 is pulled down while the mortar 9 is being injected (see FIG. 6B). At this time, the injection amount of the mortar is an amount that fills the lock bolt hole a including the mortar pack 7 minutes after the insertion of the lock bolt 1.

[Procedure 4] Insert the lock bolt 1 into the lock bolt hole a (see FIG. 6C). The mortar 9 is partially pushed down while being pushed up by the push-up fitting 3. At this time, the mortar support valve 2 moves below the lock bolt 1 as the mortar 9 descends. The mortar fall prevention valve 4 stops at the hole (see FIG. 6D).

[Procedure 5] The mortar pack 7 is pushed and broken by the tip of the lock bolt 1 (see FIG. 6E).

FIG. 7 shows an example of the mortar pack 7 used in the embodiment of FIG. The mortar pack 7 is formed by filling a mortar 9 in an insoluble paper cylinder or the like having a diameter of about 30 mm, and can be easily prepared at a construction site. The mortar pack 7 can be fitted with a fixing metal member 7 a having a cross formed with a number line at the bottom, and inserted so as to be pushed up by a mortar injection tube 8.

The mortar pack 7 is used in an auxiliary manner when there is spring water in the lock bolt hole a and the mortar is difficult to stabilize in the hole, and is not required depending on construction conditions.

Next, in order to confirm the effects of the present invention,
An experiment using a rock specimen will be described.

In the construction method of the present invention, since the effect of the push-up fitting is considered to be the largest, an experimental case (see Table 1 below) was performed using the push-up fitting as a parameter.

It should be noted that an appropriate amount should be originally injected so that the mortar can be poured without overflowing due to the insertion of the lock bolt. However, in this experiment, the mortar was completely filled in the hole. For this reason, a mortar drop prevention valve is not used.

The rock specimen used in the experiment was granite (estimated strength: 180 N / mm ² ), φ40 mm, length 60
A hole of 0 to 800 mm was drilled. Also, because of high strength granite, the hole walls are very smooth. After placing the rock bolts, the mortar was filled with rock.

[0058]

[Table 1]

The specific conditions in the casting case shown in Table 1 are as follows. For the mortar, the same dry mortar and mortar pump as used in the construction are used. A lock bolt cut to a length of 1000 mm is used. Type 1 of the push-up bracket is a conventional lock bolt fall prevention bracket. Type 2 of the push-up fitting is a push-up fitting according to claim 7 of the present application (see FIG. 3). If the number of push-up fittings is 1, attach it to the tip of the lock bolt. When the number of push-up metal fittings is 2, two-stage mounting of the front end and the intermediate portion is performed. After casting on the rock specimen, the rock is crushed after a curing period of one day or more to check the filling status.

Table 2 shows the experimental results in each of the above casting cases.

[0061]

[Table 2]

From the experimental results, it is considered that close-up filling can be achieved by installing two push-up fittings corresponding to the conventional lock bolt fall prevention fittings and using them together with the mortar support valve. However, it is obvious that the improved push-up fitting according to claim 7 of the present application is more effective.

A high mortar pushing effect was obtained by the combination of the improved push-up fitting and the mortar support valve.

[0064]

According to the construction method of the present invention, the hardening material such as mortar can be completely or almost completely filled up to the tip of the lock bolt even in the upward construction of the adhesive lock bolt, so that the cost can be reduced and the ground height can be reduced. A mountain improvement effect can be obtained.

A push-up fitting, a hardening material support valve, and a hardening material drop prevention valve as auxiliary tools used in the working method of the present invention can be easily mounted manually at a working site, and each is manufactured at low cost. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a construction procedure in one embodiment of a construction method of a lock bolt according to claims 1 to 3 of the present application.

FIG. 2 is a diagram conceptually showing a case where a plurality of hardening material push-up fittings are mounted on a lock bolt.

FIG. 3 shows one embodiment of a hardening material push-up fitting according to claims 6 and 7, wherein (a) is a perspective view seen from a side,
(b) is a plan view, and (c) is a diagram showing a state of being mounted on a lock bolt in a lock bolt hole.

FIGS. 4A and 4B show one embodiment of a hardening material support valve according to claims 4 and 5, wherein FIG. 4A is a plan view and FIG. 4B shows a state of mounting to a lock bolt in a lock bolt hole. FIG.

FIG. 5 is a perspective view showing one embodiment of a hardening material fall prevention valve according to claim 8;

FIG. 6 is a cross-sectional view showing a construction procedure when a mortar pack is used as another embodiment of the construction method of the lock bolt according to claims 1 to 3 of the present application.

FIG. 7 is a perspective view showing an example of a mortar pack used in the embodiment of FIG.

[Explanation of symbols]

a ... lock bolt hole, 1 ... lock bolt, 2 ... support valve,
2a: cut, 3: push-up bracket, 3a: mounting part, 3b
... Leg part, 3c ... Enlarged part, 4 ... Anti-drop valve, 4a ... Bolt insertion port, 4b ... Air vent, 5 ... Mortar, 6 ... Support plate, 7 ... Mortar pack, 7a ... Fixing bracket, 8 ... Mortar injection pipe , 9 ... mortar

Claims (8)

[Claims] In a method for installing a lock bolt for ground stabilization, a lock bolt is inserted by filling a lock material into a lock bolt hole, and the lock bolt is fixed by curing the hard material. A disk-shaped hardening material support valve having an outer diameter corresponding to the diameter is previously mounted on the outer periphery of the lock bolt so as to be movable in the axial direction of the lock bolt, and the hardening material is inserted when the lock bolt is inserted. Characterized in that the hardening material support valve is used to suppress the flow of the rock bolt. 2. One or more hardening material push-up fittings having a plurality of legs extending in the radial direction of the lock bolt hole are mounted on the outer periphery of the lock bolt above the hard material support valve. The method of claim 1, wherein the lock bolt is inserted while the hardening material filled in the inside is pushed up by the leg portion. 3. A hardening material fall prevention valve having a lock bolt insertion port for allowing a lock bolt to pass therethrough and an air vent hole is mounted below the hardening material support valve on the outer periphery of the lock bolt, and the lock bolt is provided. The lock bolt installation method according to claim 1 or 2, wherein when inserting the lock bolt, the hole of the lock bolt hole is closed by the hardener support valve to suppress the fall of the hardener. 4. A disk-shaped member having an outer diameter substantially equivalent to the diameter of a lock bolt hole, and a lock bolt insertion portion for inserting a lock bolt is provided at a center portion.
A hardening material support valve which is movable in the axial direction of the lock bolt while being mounted on the outer periphery of the lock bolt. 5. The hardened material support valve according to claim 4, wherein said disc-shaped member is made of rubber, and a plurality of cuts are provided at a central portion so that a lock bolt can be inserted. 6. An attaching part for attaching to an outer periphery of a lock bolt, and a plurality of legs extending radially outward of the lock bolt from the attaching part, wherein an enlarged part is provided at a tip end of the leg. A hardening material push-up fitting characterized by the following. 7. The hardened material pushing-up device according to claim 6, wherein the leg portion extends obliquely in a direction opposite to a direction in which the lock bolt is inserted into the lock bolt hole, and is urged radially outward of the lock bolt by a spring. Metal fittings. 8. A lock-bolt-shaped member having a maximum diameter larger than the hole of the lock bolt hole and a minimum diameter smaller than the hole of the lock bolt hole, and allows the lock bolt to pass through the central portion so as to be movable in the axial direction. A hardening material drop prevention valve, which has a lock bolt insertion port therefor, and one or more air vent holes are provided radially outside thereof.