JPH07259499A - Anchoring of rock bolt - Google Patents

Abstract

PURPOSE:To prevent outflow of mortar from a bore hole and to ceratinly anchor a rock bolt driven from an underground wall surface even a base rock A has a large amount of spring water. CONSTITUTION:A rock bolt 1 is driven in a bore hole 2 from a bolt insertion hole 11 opened on a rock filter 10 by way of pushing the rock filter 10 having water permeability into an opening end part 2a of the bore hole 2 after injecting and filling mortar 3 in the bore hole 2 drilled on a base rock A. Favourably, as the rock filter 10, one provided with a filter main body 12 consisting of a deformable water permeable material of a sponge, etc., on the outer periphery of the bolt insertion part 11 consisting of a tube with a bore diameter free to insert the rock bolt 1 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a rock bolt into a rock mass from an inner wall surface to fix the rock in civil engineering work such as excavation in a mountain tunnel, and more particularly to a method suitable for fixing at a spring location. Is.

[0002]

2. Description of the Related Art In tunnel excavation work for mines,
A rock bolt is immediately driven into the excavated underground rock to fix the rock, and concrete is sprayed on the underground wall to lining the rock to support and strengthen the rock. As shown in FIG. 5, the lock bolt 1 includes a rebar-shaped fixing portion 1a having a conical tip and a large number of beads protruding from the outer peripheral surface, and a male screw portion 1b formed at the rear end. There is a rock bolt 1 from the mine wall surface A'to the bedrock A when driving it.
The borehole 2 is appropriately bored longer than the effective length of the fixing portion 1a, the mortar 3 is injected and filled into the borehole 2, and then the lock bolt 1 is driven. Thereafter, the fixing portion 1a of the lock bolt 1 is fixed to the borehole 2 by hardening the mortar 3.
Once fixed inside, the pressing metal fitting 4 is inserted into the male screw portion 1b of the lock bolt 1 protruding into the mine from the opening end of the bore hole 2, and the nut 5 is screwed in and tightened.

[0003] By the way, in the construction work on the bedrock having spring water, a drain hole 2'is bored at a position adjacent to the bore hole 2 and the drain water from the drain hole 2'is used to drain the spring water in the bore hole 2. We are trying to prevent it. However, in a place where a large amount of spring water that cannot be dealt with even by such a drainage hole 2'is generated, the mortar 3 is not sufficiently hardened by the spring of groundwater into the borehole 2 and part of it Is washed away to the outside of the bore hole 2, so that it becomes impossible to fix the entire surface of the lock bolt 1.

Therefore, in such a case, as shown in FIG. 6, a capsule type structure in which a special cement that rapidly hardens and a small amount of resin that expands instantaneously upon contact with water are separately enclosed in water-absorbing capsules. The fixing material 6 is once immersed in water for several minutes to absorb water, and the fixing material 6 is pushed into the borehole 2 in place of mortar, and then the lock bolt 1 is driven. That is, the capsule-type fixing material 6 is filled in the borehole 2 with an encapsulant such as special cement extruded from the capsule by driving the lock bolt 1, and the inside of the borehole 2 is blocked by the water-stopping force of the resin which is rapidly expanded and hardened by water absorption. It blocks the inflow of spring water into the lock bolt 1 and fixes the lock bolt 1 by hardening the special cement.

[0005]

However, even with the construction method using the capsule type fixing material 6, it is inevitable that a certain amount of cement will flow out, so that it is difficult to securely fix the lock bolt 1 to the entire surface. Is. Further, since it hardens quickly after absorbing water, it is necessary to insert the lock bolt 1 into the borehole 2 and drive the lock bolt 1 very efficiently. However, if the amount of water absorption is large, the capsule-type fixing material 6 expands too much and the borehole 2 May not fit well, and if the inner surface of the borehole 2 is rough, smooth insertion may not be possible. Moreover, since the capsule-type fixing material 6 has a special structure, it is expensive, and a large amount of the capsule-type fixing material 6 will be wasted if it is stored in a humid place or if it is wetted with water before use. There is a problem that it hardens and becomes unusable, increasing the construction cost.

The present invention has been made under the circumstances as described above, and its technical problem is that during excavation work, mortar leaks from the borehole even if the bedrock has a large amount of spring water. It is intended to provide a method capable of reliably preventing the lock bolt driven from the inner wall surface of the mine.

[0007]

The above-mentioned technical problems are as follows.
The present invention can effectively solve the problem. That is, the fixing method of the lock bolt according to the present invention is performed by injecting and filling mortar into the bore hole drilled in the rock from the underground wall surface, and then pushing the water permeable lock filter into the open end of the bore hole to open the lock filter. The lock bolt is driven into the bore hole from the bolt insertion portion. In this case, it is preferable that the lock filter has a filter main body made of a deformable water-permeable material such as a sponge on the outer periphery of a bolt insertion portion made of a tube having a hole diameter capable of inserting the lock bolt.

[0008]

According to the fixing method of the present invention, after the mortar is filled in the bore hole, the lock bolt is driven through the bolt insertion portion of the lock filter applied to the opening end portion of the bore hole. And a lock bolt to close the open end. Since the lock filter has water permeability and blocks the outflow of mortar and discharges only the water in the borehole, the entire fixing of the lock bolt can be effectively performed by hardening the mortar. For example, the lock filter has a structure in which a filter body made of a deformable water-permeable material such as sponge is provided on the outer circumference of a tube having a hole diameter through which a lock bolt can be inserted. You can

[0009]

1 to 4 show a preferred embodiment of a lock bolt fixing method according to the present invention in the order of steps. That is, according to the method of this embodiment, first, as shown in FIG. 1, a borehole 2 similar to the conventional one is bored from the upper wall surface A ′ of the excavated tunnel to the bedrock A at substantially right angles to the wall surface A ′. The bore hole 2 has a length of about 3 m and a hole diameter of φ38 mm, for example, in consideration of the size of the fixing portion 1a of the lock bolt 1 described later.

Next, as shown in FIG. 2, an appropriate amount of mortar 3 is injected and filled into the bore hole 2, and then the lock filter 10 is applied to the open end portion 2a of the bore hole 2 and pushed, and further from the lock filter 10. Borehole 2
Drive the lock bolt 1 into the inside. Rock filter 10
As shown in the enlarged perspective view of FIG. 3, the filter main body 12 made of a cylindrical sponge is provided on the outer periphery of the middle portion in the longitudinal direction of the bolt insertion portion 11 typically made of a synthetic resin tube such as vinyl chloride. And the hole diameter of the bolt insertion portion 11 is equal to that of the fixing portion 1a of the lock bolt 1.
The outer diameter of the filter body 12 is, for example, 90 mm, which is sufficiently larger than the hole diameter of the bore hole 2, and the length is 100 mm.

That is, the lock filter 10 is applied to the opening end portion 2a of the bore hole 2, and the bolt insertion portion 11 thereof is placed.
As shown in FIG. 4, the fixing portion 1a of the lock bolt 1 is inserted into the lock bolt 1 and is pushed in as it is, so that the filter body 12 of the lock filter 10 is appropriately compressed and deformed to be crimped to the opening end 2a of the bore hole 2. At the same time, the fixing portion 1 a of the lock bolt 1 is driven into the bore hole 2 through the bolt insertion portion 11. Therefore, the bolt insertion portion 1a is closed by the fixing portion 1a of the lock bolt 1,
A space between the inner wall of the open end 2a and the lock bolt 1 is closed by a compressed filter body 12.

In this state, since the bolt insertion portion 11 of the lock filter 10 is made of a synthetic resin tube such as vinyl chloride, the inner peripheral surface thereof is the fixing portion 1 of the lock bolt 1.
The mortar 3
Does not create a gap that allows the outflow of Further, the sponge constituting the filter body 12 has a remarkable water permeability due to the capillary phenomenon by the innumerable continuous bubbles 12a, while effectively blocking the passage of mortar particles, so that the borehole 2
When the water content of the mortar 3 increases due to the outflow of ground water inside, only the increased water content is discharged from the filter body 12, and the outflow of the mortar 3 is prevented. In addition, when the amount of spring water is relatively large, the borehole 2 is previously
Drill a drain hole 2'at a position adjacent to
It is preferable to reduce the amount of spring water inside.

According to the method of this embodiment, since the mortar 3 is retained in the borehole 2 without being washed away by the spring water, the inner wall of the borehole 2 and the lock bolt 1 are retained.
Since the resin is hardened in a state of being bonded to the entire surface of the fixing portion 1a and the water content of the mortar 3 is kept constant, sufficient strength is exhibited. For this reason, the rock bolt 1 can be reliably fixed on the bedrock A where spring water is generated, and normally, even if the water drainage hole 2'is not drilled, it is sufficiently compatible with the water discharge of the mortar 3 at the spring water location. Therefore, the work man-hour can be reduced. Further, the lock filter 10 can be provided at a low cost because it has a simple structure in which a sponge is provided on the outer circumference of a synthetic resin tube such as vinyl chloride, and furthermore, the capsule-type capsule-type fixing material shown in FIG. 6 described above. 6
As described above, the smooth surface of the borehole 2 does not impair the smooth progress of the work, and the material loss is small, so that the construction cost can be reduced.

When the lock bolt 1 is fixed by hardening the mortar 3 in the bore hole 2 after a predetermined time has passed, the male screw portion 1b of the lock bolt 1 protruding from the opening end portion 2a of the bore hole 2 into the pit as in the conventional case. Insert the metal fitting 4 and screw in the nut 5 to tighten it.

The present invention is not limited to the illustrated embodiment. For example, in the lock filter 10, the filter body 12 is a deformable water-permeable material other than sponge,
For example, non-woven fabric, paper, or a fiber bundle may be used.

[0016]

According to the present invention, the following effects can be obtained. (1) Since the mortar filled in the borehole is not washed away by the spring water, only the water content increased by the spring water is discharged to the outside of the borehole through the lock filter and the water content of the mortar is kept constant. The lock bolt can be fully fixed to the rock at the water location. (2) Since it is not necessary to form a drain hole near the borehole unless the place where a large amount of spring water that exceeds the permissible drainage amount due to the lock filter is generated, it is possible to reduce labor and save labor. (3) The lock filter can be provided at a low cost, and the material loss during the construction is small, so that the construction cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step of boring a borehole in a rock from an inner wall surface in a preferred embodiment of a lock bolt fixing method according to the present invention.

FIG. 2 is a cross-sectional view showing a step of injecting and filling mortar into a borehole in the above embodiment.

FIG. 3 is a perspective view showing a lock filter used in the above embodiment.

FIG. 4 is a cross-sectional view showing a step of pushing a lock filter into an end portion of an opening of a borehole and driving a lock bolt in the above embodiment.

FIG. 5 is a cross-sectional view showing a conventional example of a lock bolt fixing method.

FIG. 6 is a cross-sectional view showing another conventional example of a lock bolt fixing method.

[Explanation of symbols]

 1 Rock Bolt 2 Borehole 2a Open End 3 Mortar 10 Rock Filter 11 Bolt Insertion Part 12 Filter Body A Rock Mass A'Underwall

Claims (2)

[Claims] 1. A step of boring a borehole in a rock from an inner wall surface, a step of injecting and filling mortar into the borehole, and a rock filter having water permeability being pushed into an opening end portion of the borehole to be opened in the rock filter. And a step of driving the lock bolt into the bore hole from the bolt insertion portion. 2. The lock filter according to claim 1, wherein a filter main body made of a deformable water-permeable material such as a sponge is provided on the outer periphery of a bolt insertion portion formed of a tube having a hole diameter capable of inserting the lock bolt. A method of fixing a lock bolt, characterized in that