JP3205546B2 - Lock bolt nut - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nut applied to a lock bolt for supporting a tunnel or reinforcing a ground on a slope, and more particularly, to a unit length such as an FRP lock bolt or a lock bolt made of irregular shaped thread-bar rebar. The present invention relates to a lock bolt nut suitable for use with a lock bolt having a low screw strength (thread tensile strength).

[0002]

2. Description of the Related Art In the NATM method generally used for tunnel construction in mountains or the like, after excavating the ground (after hardening the wall with cement if necessary), a large number of the rocks are vertically inserted from the wall into the rock mass. The ground near the wall of the tunnel is strengthened by driving the rock bolt and fixing it with a predetermined fixing material such as cement or resin, and it is supported by the ground inside the rock, preventing the collapse around the inner wall (Shoring). The rock bolt is driven vertically into the side wall of the construction tunnel and fixed, then left in the ground as it is for support for reinforcement of the ground for a long time, and it is driven into the face mirror or sillot at the tip of the construction tunnel and fixed. However, there are temporary supports for temporary support that are cut off with tunnel excavation only after temporary reinforcement.

[0003] In the case of the former support, a steel lock bolt is preferably used as a structural member having a high strength as much as possible. After the casting, the ground is fastened to the ground using a seat and a nut, such as a plate and a washer, so as to firmly fix the ground for a long period of time. As the type, for example, a deformed bar, a twisted bar, a deformed threaded reinforcing bar (the surface of the bar is thread-shaped), and the like are used. Further, in the case of the latter temporary support, an FRP lock bolt (a bolt obtained by solidifying a reinforcing fiber bundle such as glass fiber with a thermosetting resin) is used so that it can be cut later. The FRP lock bolt and the lock bolt made of irregular shaped thread-bar rebar have a smaller screw strength per unit length (tensile strength of the screw thread) than a normal steel lock bolt in which the screw thread is separately processed. For this reason, when a nut combined with a seat plate is fitted and fixed to the FRP lock bolt or the deformed thread-bar reinforced lock bolt after the casting, it is necessary to reduce the tensile load applied to the thread at the fitting portion.

Therefore, as shown in FIG. 5, the fitting length L between the lock bolt (FRP lock bolt) 1 and the nut 5 is considerably lengthened, and the nut 5 is elongated to secure a sufficient length in the female screw portion. I do. However, with such a structure,
The fitting length L several times as large as that of the steel lock bolt is required, and the end of the lock bolt 1 including the seat plate 4 and the nut 5 protrudes largely into the tunnel space.
As a result, when the sheet 7 such as a waterproof sheet and an isolation sheet is laid in the next process during the construction of the tunnel, the sheet 7 may be hindered by the protruding lock bolt head. Unevenness occurs, and the desired sheet performance cannot be exhibited, and moreover, there is a problem that the sheet is damaged at the time of placing the secondary lining concrete later.

In order to solve the above problems, lock bolts have been proposed in which the length of the lock bolt is reduced by using a nut having a special shape (Japanese Patent Application Laid-Open Nos. 9-13898 and 9-13898). -49399). FIG.
FIG. 1 is a perspective view of an FRP lock bolt proposed in the specification of Japanese Patent Application Publication No. 9-13898, in which an external thread portion (rope screw) 1 a is formed on the outer periphery of the FRP lock bolt 1, and the lock bolt 1 has a female thread portion of a predetermined length. Special shaped nut 5
Can be screwed. The nut 5 is the round hole 4 of the seat plate 4.
a comprising a shaft portion 5a which can be loosely inserted into a and a head portion 5b which is fixed to a hand side of the shaft portion and is larger than the hole 4a of the seat plate;
A female screw 5c of a predetermined length is formed on the inner surface so as to be continuous from the head to the shaft.

As shown in FIG. 7, a lock nut 1 is fixed to a ground by fitting a nut 5 in combination with a seat plate 4 to a lock bolt 1 driven into a ground 6. That is, a borehole 8 is bored in the ground 6, the mortar 3 as a fixing material is injected into the borehole 8, and then the lock bolt 1 is driven. Thereafter, with the shaft portion 5a of the nut 5 loosely inserted into the hole 4a of the seat plate 4, the female screw portion of the nut 5 is fitted into the male screw portion of the head of the lock bolt 1. As the fitting proceeds, the shaft portion 5a of the nut 5 is
Then, the seat plate 4 is pressed against the ground by the head 5b of the nut 5, and the lock bolt 1 is firmly fixed to the ground. Most of the nut 5 goes into the borehole,
Almost the thickness of the nut head 5 and the seat plate 4 is just outside, so that the protruding length L 'of the lock bolt can be shortened and does not hinder other operations. In addition, when laying sheets such as an isolation sheet, unevenness is reduced, so that desired sheet performance can be exhibited.

FIG. 8 is an explanatory view of a lock bolt nut proposed in Japanese Patent Application Laid-Open No. 9-49399, in which a tapered flange 5b 'having a small diameter at the distal end with respect to a proximal end 5a'.
5 ′ integrally formed with the nut and a base end 5 of the nut
A bearing plate 4 'through which a' is inserted is prepared.
At the time of construction, a borehole 8 is formed in the ground 6, a mortar 3 as a fixing material is injected into the borehole 8, and then a lock bolt 1 is driven. Thereafter, the base end 5a 'of the nut 5' is inserted into the hole of the bearing plate 4 ', and the nut 5' is inserted into the head side of the lock bolt 1 inserted into the bore hole 8.
From the proximal end side. The bearing plate 4 'is pressed against the ground by the tapered flange 5b' of the nut 5 ',
The lock bolt 1 is firmly fixed to the ground. Nut 5 '
The base end 5a 'of the lock bolt enters the bore hole, and only the thickness corresponding to the combination of the tapered flange 5b' and the bearing plate 4 'just goes out, and the protruding length of the lock bolt can be shortened.

[0008]

As described above, the use of a specially shaped nut has the advantage that the protruding length of the lock bolt can be reduced. However, the special-shaped nut secures a screw-fitting length by inserting a shaft portion or a base end portion having a female thread into a bore hole.
For this reason, when the fixing material is filled in the bore hole, as shown in FIGS.
a 'enters the fixing material, and after the curing, the nut cannot be moved. When a lock bolt is actually installed, it may be necessary to confirm that it is sufficiently fixed to the ground by an axial force test (construction management). It is necessary to remove the nut, and attach the tester's exter bar to the lock bolt. However, the conventional lock bolt nut cannot be removed after the fixing material has hardened, and there is a problem in construction management. Further, when it is necessary to re-tighten (re-tighten) the nut after fixing, the conventional lock bolt nut has a problem that the nut cannot be completely re-tightened after the fixing material is hardened. In view of the above, an object of the present invention is to provide a lock bolt nut capable of shortening the protrusion length of the lock bolt and capable of attaching and detaching and tightening the nut even after the fixing material is hardened.

[0009]

According to the present invention, there is provided, according to the present invention, a head part and a shaft part, and a screw part to be screwed with a screw part formed on the outer periphery of a lock bolt from the head part to the shaft part. This is achieved by a nut for a lock bolt, which is provided with a continuously variable thickness to the end face of the shaft portion. By providing a variable thickness trimming body, for example, a non-permeable sponge, on the end surface of the shaft portion, the head of the lock bolt fitted with the nut is cut off from the hardened fixing material (fixing portion). The nut can be removed from the lock bolt if necessary. Furthermore, since the nut can move in the axial direction with respect to the lock bolt by the thickness of the spliced body,
After the fixing material has hardened, the nut can be re-tightened (re-tightened).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (a) Configuration of Nut FIG. 1 is an explanatory view of a lock bolt nut according to the present invention.
(A) is a top view, (b) is a cutaway side view. The lock bolt nut 10 of the present invention includes a substantially hexagonal head 11 and a shaft portion 12 which are integrally formed.
A skirt-shaped trimming body 13 having a variable thickness, for example, a trimming body formed of a non-permeable sponge is adhered to the end face of the second. When the nut 10 is fitted into the head of a lock bolt driven into the borehole, the rim body 13 fixes the nut body (head 11, shaft 12) to the fixing material (fixing part) loaded in the borehole. It has the function of isolating (edge cutting) from. Further, a female screw portion 14 to be screwed with a screw portion formed on the outer periphery of the lock bolt is formed to penetrate from the head 11. However, the inner surface of the trimming body 13 is a cylindrical hole having a diameter slightly smaller than that of the female screw portion 14. A material other than a sponge can be used as the material of the edge cutting member 13 as long as the material has a variable thickness and does not penetrate a fixing material (for example, mortar). As shown in the figure, the edge cutting body 13 has a larger diameter in the form of a skirt, as shown in the figure, so that the edge cutting effect is more enhanced.

(B) Construction method FIG. 2 is an explanatory view of a construction method of a lock bolt. A conical cap 25 is attached to the tip of a lock bolt main body 26 made of a deformed thread-bar rebar, and the nut 10 into which the square washer 20 is inserted is fitted into the rear end of the lock bolt main body 26 in advance. The square washer 20 has a through hole 20a at the center of the square, which is larger than the shaft diameter of the nut 10 and smaller than the head diameter. Fig. 3
As shown in (1), threaded joints are formed over the entire length, where P is the pitch of the joints, H is the height of the joints, and T is the gap between the joints. As in the case of the conventionally known fully-adhesive lock bolt, a borehole 23 having a predetermined depth is drilled from the inner wall 22 of the excavated tunnel into the rock mass of the ground 21 by a drilling machine, and an injection hose or the like is used in the borehole 23. Fixing material,
For example, mortar 24 is injected. Thereafter, a lock bolt body prepared in advance is inserted and driven. That is, the lock bolt body is inserted and driven until the square washer 20 presses against the inner wall of the ground.

In this state, the fixing material 24 is cured. As shown in FIG. 4A, even when the fixing material is cured, the heads of the lock bolts (nut body portions 11 and 12) are
Is cut off from the fixing material (fixing portion) 24 which is hardened by the action of (1). For this reason, if necessary, the nut 10
Can be removed from the lock bolt main body 26. Also, the nut 10 is axially moved relative to the lock bolt main body 26 by the thickness d of the edge cut body (sponge) 13 (FIG. 4).
(b) It can be moved (to the right), so that the nut can be re-tightened (re-tightened) even after the fixing material has hardened.
FIG. 4B shows a state in which tightening has been performed. Therefore, after the fixing material is cured, if the nut is re-tightened (re-tightened) as necessary, the lock bolt main body 26 and the periphery of the hole wall of the bore hole 23 are integrally fixed, and the hard bolt tip is driven into a hard interior. By being supported by the bedrock, collapse around the pit wall is prevented. Also, later, the ground looseness LS
When (see FIG. 4 (a)) occurs, the ground reinforcement effect of the lock bolt can be improved by appropriately re-tightening (re-tightening) the nut 10.

As described above, the protrusion of the nut 10 can be reduced while securing a sufficient screw fitting length with the lock bolt main body 26. In addition, the lock with the nut fitted by the action of the rim body 13 is provided. The head of the bolt can be cut off from the hardened fixing material (fixing portion), and the nut can be removed from the lock bolt if necessary, and the nut can be re-tightened (re-tightened) after the fixing material has hardened. As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0014]

As described above, according to the present invention, since the edge portion of the shaft portion is provided with an edge-cutting member having a variable thickness, for example, a non-permeable sponge, the fixing material (fixing material) is obtained by hardening the head of a lock bolt fitted with a nut. Part), and the nut can be removed from the lock bolt if necessary, so that there is no problem in construction management. Further, according to the present invention, since the nut can be moved in the axial direction with respect to the lock bolt by the thickness of the spliced member, the nut is appropriately re-tightened (re-tightened) after the fixing material is hardened. The effect of reinforcing the ground can be improved. Further, according to the present invention, the amount of protrusion from the ground can be reduced, so that there is no need for a waterproof sheet protective cap or mat to be put on the bolt head during sheet construction. As a result, it is possible to reduce the labor for attaching the waterproof sheet protective cap.

[Brief description of the drawings]

FIG. 1 is a structural view of a bolt nut according to the present invention.

FIG. 2 is an explanatory view of a method of installing a lock bolt.

FIG. 3 is an explanatory view of a deformed threaded bar.

FIG. 4 is an explanatory diagram of an operation of the edge cutting body.

FIG. 5 is an explanatory view of a problem of a conventional FRP lock bolt.

FIG. 6 is a perspective view of an FRP lock bolt provided with a specially shaped nut.

FIG. 7 is an explanatory view of a construction method of an FRP lock bolt.

FIG. 8 is another explanatory view of an FRP lock bolt provided with a specially shaped nut.

[Explanation of symbols]

 10. Nuts for lock bolts 11. Approximately hexagonal heads 12. Shafts 13. Edge cuts 14. Internal thread

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) E21D 20/00-21/02 E02D 17/20 106 F16B 37/14

Claims (1)

(57) [Claims] A screw part provided with a head part and a shaft part and screwed with a screw part formed on the outer periphery of the lock bolt;
A nut for a lock bolt, wherein the nut is provided continuously from the head portion to the shaft portion, and further has an edge-cut body having a variable thickness on an end surface of the shaft portion.