JPH0913898A - Nut for rock bolt - Google Patents

Abstract

PURPOSE: To shorten the projected length of a rock bolt. CONSTITUTION: A rock bolt 20 is driven into a bore hole drilled in the natural ground and, then, the shaft section 42 of a nut 40 is loosely inserted in the round hole 31 of a washer 30. In this state, the internal thread section 41 of the nut 40 is coupled to an external thread section 21 on the base end external surface of the rock bolt 20. With the development of the coupling work, the shaft section 42 of the nut 40 advances into the bore hole, and the washer 30 is pressed to the subsoil with the head 43 of the nut 40, thereby firmly anchoring the rock bolt 20 to the subsoil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock bolt nut for fixing a rock bolt to a natural rock by fitting it into a rock bolt used for fixing a natural rock in a tunnel construction etc. in combination with a seat plate such as a plate and a washer. In particular, the lock bolt has a low screw strength per unit length (tensile strength of the thread), which is made of FRP or resin and has a thread formed on the outer circumference so that it can be cut later because it is temporary support work. The present invention relates to a nut for a lock bolt.

[0002]

2. Description of the Related Art In the NATO method (NATM method), which is common in tunnel construction in mountains, etc., after excavating the natural ground (when necessary, after cementing the wall with cement), a large number of pieces are vertically inserted into the bedrock. The rock bolts are driven in and fixed with a predetermined fixing material such as cement or resin to strengthen the ground near the tunnel wall and support the ground inside the rock to prevent collapse around the inner wall. I am doing it (support work). The lock bolt is vertically driven into the side wall of the construction tunnel and fixed, and then left in the ground as it is for reinforcement of the ground for a long time, and it is driven into the face mirror and silot etc. at the tip of the construction tunnel and fixed. However, it is for temporary support work that will be cut off along with the tunnel excavation with only temporary reinforcement.

In the former case of supporting work, it is desirable that the structural member has as high strength as possible, and that made of steel is used. After the driving, the plate is tightened to the ground using a seat plate such as a plate and a washer and a nut, so that the fixing is firmly performed for a long period of time. On the other hand, in the case of the latter temporary support work, a structural member made of FRP, resin or the like and having a screw formed on the outer periphery and having a low screw strength per unit length (tensile strength of the thread) so that it can be cut later can Used. However, in the case of temporary installation, since it is often removed within a short period of time, it is usually not tightened with nuts, but simply placed in the ground.

Here, in the case of a pattern bolt which is laid radially and vertically to the side wall of a construction tunnel, when the width is not widened later, as shown on the right side of FIG. 4, the steel lock bolt 1 is used as a plate, washer or the like. The seat plate and nuts are used to tighten and support the ground, but if there is a plan to excavate for widening later, temporary support work will be performed with a relatively low-strength rock bolt such as FRP or resin. However, since the temporary installation period becomes long, there is a case where it is desired to fit a nut combined with a seat plate such as a plate and a washer into the low-strength lock bolt 2 as shown on the left side of FIG. 4 in order to increase the fixing strength. However, with a structural member made of FRP, resin, or the like, it is difficult to cut the male screw portion on the outer surface at a free pitch like a steel lock bolt. From this fact, conventionally,
As shown in FIG. 5, when the material of the lock bolt 2 is molded, its outer shape is processed into a so-called rope screw shape (the pitch is coarser than the male screw portion formed on the steel lock bolt).

The nut 3 used for the rope bolt processed lock bolt 2 also has a female thread portion of the rope screw. In such a lock bolt 2 and a nut 3 which are rope-thread processed, the lock bolt 2 after being cast
Insert the nut 3 combined with the seat plate 4 such as plate and washer into the and tighten the lock bolt 2 to the natural ground 5,
When fixing, it is necessary to reduce the tensile load applied to the thread of the fitting portion of the lock bolt 2 and the nut 3 so that even a material having a low tensile strength of the thread can sufficiently withstand. For this reason, as shown in FIG. 5, the fitting length L of the lock bolt 2 and the nut 3 must be considerably long, and the nut 3 must be long to secure a sufficient length in the female thread portion. I won't.

[0006]

However, in the conventional nut 3, since the plate which hits the inner wall of the natural ground and the seat plate 4 such as the washer are pressed by one end surface of the nut 3, the nut 3 is long. In that case, the end portion of the lock bolt 2 including the nut 3 largely projects into the tunnel space. As a result, when interfering with other work during the tunnel construction, or when laying sheets 6 such as a waterproof sheet and an isolation sheet in the next process, the sheets 6 are blocked by the protruding lock bolt heads. There was a problem that unevenness occurred and the desired seat performance could not be achieved.

In view of the above, an object of the present invention is to provide a lock bolt nut capable of shortening the protruding length of the lock bolt.

[0008]

According to the present invention, there is provided a lock bolt having a female screw portion of a predetermined length which can be screwed into a lock bolt having a male screw portion formed on the outer periphery thereof and which is driven into the ground. In the nut for the lock bolt that fixes the lock bolt to the ground by fitting it together with the seat plate, the shaft part that can be loosely inserted into the hole of the seat plate and the proximal side of the shaft part are fixed, and Consists of a large head,
This is achieved by forming an internal thread portion of a predetermined length so as to be continuous from the head portion to the shaft portion.

[0009]

According to the present invention, when the temporary support work for a long temporary period is performed using the lock bolt, the bore hole is bored in the natural ground. Then, after the lock bolt is driven, the shaft portion of the nut is loosely inserted into the hole of the seat plate, and the female screw portion of the nut is fitted into the male screw portion of the outer surface of the lock bolt head. As the fitting progresses, the shaft portion of the nut enters into the borehole, the seat plate is pressed against the ground by the head of the nut, and the lock bolt is firmly fixed to the ground. As a result, when the nut combined with the seat plate is fitted into the lock bolt, most of the nut will go into the bore hole, and the thickness of the nut head and seat plate will almost go out. The projecting length of can be shortened so that it does not interfere with other work, and the unevenness becomes small when laying sheets such as waterproof sheets and isolation sheets in the next process, so the desired seat performance is exhibited. be able to.

[0010]

1 is an external perspective view of a lock bolt set according to an embodiment of the present invention, and FIG. 2 is a perspective sectional view showing a combination of a washer and a nut. The lock bolt set 10 is composed of a lock bolt 20 and a combination of a square washer 30 and a nut 40 for tightening the lock bolt 20 on the ground. The lock bolt 20 is made of FRP, resin, or the like and has a relatively low strength so that it can be cut later, and a male screw portion 21 formed by spirally forming a rope screw is provided on the outer surface of the lock bolt 20 ( The pitch of the male screw portion 21 is coarser than that of the steel lock bolt). The tip of the lock bolt 20 is obliquely cut so that it can be smoothly driven into the natural ground.

Both the washer 30 and the nut 40 are made of steel or FRP. A round hole 31 is formed in the washer 30, and the nut 40 can be loosely inserted into the round hole 31. On the other hand, inside the nut 40, a female screw portion 41 that is screwed into the male screw portion 21 of the lock bolt 20 is formed over the entire length (see FIG. 2). This nut 40
Is formed to have a sufficient length so that the tensile load applied to the screw thread becomes small when fitted with the lock bolt 20.

The nut 40 has a cylindrical shaft portion 42,
The head portion 43 is provided at one end of the shaft portion 42, and the shaft portion 42 occupies most of the length of the nut 40. The shaft portion 42 is formed to have an outer diameter slightly smaller than that of the round hole 31 of the washer 30, and the shaft portion 42 can be freely inserted into the round hole 31. On the other hand, the head portion 43 is formed to be much larger than the round hole 31 so that the washer 30 fitted in the shaft portion 42 does not come off. The head 43 has a hexagonal shape so that a tightening tool can be fitted and rotated.

FIG. 3 is an explanatory view showing how to use the lock bolt set 10. For example, in the case of temporarily supporting the inner wall of the construction tunnel, first, the borehole 50 is bored in the natural ground 5 (see FIG. 3 (1)), and the lock bolt 20 is inserted into the borehole 50 using a driving tool. Placing (Fig. 3
(See (2)). If it is a short-term temporary installation such as a face mirror or a silot, it can be left as it is, but if the temporary installation is relatively long due to widening later, a nut 40 combined with the washer 30 is fitted to firmly fix the fixing. .

That is, after the lock bolt 20 is driven to a position where the end portion on the proximal side of the lock bolt 20 projects a little more than the total thickness of the washer 30 and the head portion 43 of the nut 40, the shaft portion 42 of the nut 40 is washered. In the state of being inserted into the round hole 31 of 30, the female screw portion 41 of the nut 40 is screwed into the male screw portion 21 of the lock bolt 20 from the tip side of the shaft portion 42 to be fitted therein. At this time, nut 4
A tightening tool is fitted on the head 43 of 0 and rotated. As the fitting of the nut 40 progresses, the shaft portion 41 gradually enters the bore hole 50. Washer 3
0 is pushed by the head 43 of the nut 40 to move forward, and the ground 51
When the nut 40 is further tightened where it hits the lock bolt 20, the lock bolt 20 is firmly fixed to the ground 51 (Fig. 3 (3)).
reference).

Nut 40 in combination with washer 30
When the tightening is completed, the fitting length of the lock bolt 20 and the nut 40 (see symbol L in FIG. 3 (3)) is sufficiently long, so that even if the pitch of the screw is rough, the tensile load applied to the screw thread is small. The lock bolt 20 having a relatively low tensile strength of the screw thread can sufficiently withstand. Also,
The length of the lock bolt 20 protruding from the ground is a little shorter than the combined thickness of the washer 30 and the head 43 of the nut 40. Therefore, it does not interfere with other work in the construction tunnel, and as shown in FIG. 3 (4), when the sheets 52 such as a waterproof sheet and an isolation sheet are stretched after the lock bolt 20 is fixed. In addition, the unevenness generated in the sheets 52 can be reduced, and desired sheet performance can be satisfactorily exhibited.

When the place where the lock bolt 20 is to be excavated for the purpose of widening the tunnel after the temporary construction period is over, the lock bolt 20 is made of FRP, resin or the like and can be easily cut. Does not hinder.

According to this embodiment, when the nut 40 combined with the washer 30 is screwed onto the lock bolt 20 and fitted, the washer 30 is pressed against the head portion 43 while being fitted on the shaft portion 42 of the nut 40. When the nut 40 is contacted with the ground and the nut 40 is tightened, the lock bolt 20 is firmly fixed to the ground by a reaction. As the fitting of the nut 40 progresses, the shaft portion 42 is inserted from the tip to the bore hole 5
Since it goes into 0, of the lock bolt 20,
Since the thickness of the washer 30 and the head 43 is projected to the outside, the projecting length is extremely short, which does not interfere with other work in the construction tunnel, and also locks the lock. Even when the sheets 52 such as the waterproof sheet and the isolation sheet are stretched after the fixing of the bolts 20, the irregularities generated in the sheets 52 can be made small, and the desired sheet performance can be exhibited well.

In the above-mentioned embodiment, the lock bolt is made of FRP, resin or the like and has a screw formed on the outer circumference. However, it may be a lock bolt made of other material, or as a seat plate. Although the washer is used, a plate (bearing plate or the like) may be used.

[0019]

As described above, according to the lock bolt nut of the present invention, with the shaft portion of the nut loosely inserted in the hole of the seat plate, the female screw portion of the nut is fitted into the male screw portion on the outer surface of the lock bolt head. Then, as the fitting progresses, the shaft part of the nut enters the bore hole, the seat plate is pressed against the ground by the nut head, and the lock bolt is tightened to the ground. When the nut combined with is inserted, most of the nut goes into the borehole and the head only goes out, so the protruding length of the lock bolt can be shortened and it does not interfere with other work. When laying sheets such as a waterproof sheet and an isolation sheet in the next step, the unevenness becomes small, so that the desired sheet performance can be exhibited.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a lock bolt set according to an embodiment of the present invention.

FIG. 2 is a perspective cross-sectional view of a combination of a washer and a nut.

FIG. 3 is an explanatory diagram of how to use the lock bolt set.

FIG. 4 is an explanatory view of a construction state of a pattern bolt.

FIG. 5 is an explanatory diagram of a problem of a conventional temporary support work lock bolt set.

[Explanation of symbols]

 10 lock bolt set 20 lock bolt 21 male screw part 30 washer 31 round hole 40 nut 41 female screw part 42 shaft part 43 head

Claims (1)

[Claims] 1. A lock bolt having a female screw portion of a predetermined length which can be screwed into a lock bolt having a male screw portion formed on the outer periphery, and is fitted into a rock bolt driven into the ground in combination with a seat plate. In the nut for the lock bolt that fixes the to the ground, it consists of a shaft part that can be loosely inserted in the hole of the seat plate and a head that is fixed to the proximal side of the shaft part and is larger than the hole of the seat plate. A nut for a lock bolt, characterized in that a female thread portion of a predetermined length is formed so as to be continuous.