JP3875979B2 - Rock bolt - Google Patents

Description

  The present invention relates to a rock bolt used in tunnel construction, slope restraining work, or the like.

  Generally, the lock bolt is a bolt material inserted into the ground, a bearing plate attached to the head of the bolt material to disperse the force transmitted from the bolt material, and the bearing plate as a bolt. It is comprised from the nut fixed to the head of a material, and it constructs in the state which the head of the bolt material protruded from the ground. When the lock bolt with this structure is used as a supporting material for tunnel construction, the head of the bolt material protrudes to the inside of the tunnel, so that the waterproof sheet installed when lining concrete is placed will not be damaged. It was necessary to attach a plastic cap or non-woven fabric to the head of the bolt material. These operations need to be applied to all the rock bolts installed in large quantities in the tunnel construction, and since they are performed manually, it takes time and hinders the shortening of the construction time.

Conventionally, in order to save the labor of such work and perform an efficient work, the bolt material 120 is inserted after the fixing material 150 is filled into the lock bolt insertion hole 140 drilled in the ground G as shown in FIG. A lock bolt 110 having a configuration in which a bearing plate 130 with a nut in which a bearing plate 131 and a nut 132 are integrated by welding S1 is attached to the head of the bolt material 120 is disclosed. At this time, the bearing plate 130 with nut is attached to the head of the bolt member 120 by placing the bearing plate 131 so that it is inside the tunnel and the nut 132 is outside the tunnel. And after attaching the bearing plate 130 with a nut to the head part of the bolt material 120, the extra bolt head part 160 which protrudes in a tunnel is cut | disconnected, The lining concrete 190 is maintained, maintaining the function as a lock bolt. There is an advantage that it is not necessary to attach a plastic cap or a nonwoven fabric for preventing breakage of the waterproof sheet 180 installed at the time of placing (see Patent Document 1).
JP-A-7-119393 ([0006] to [0015], FIG. 1)

However, the above-described conventional lock bolt structure has the following problems.
(1) It is necessary to thread the head of the bolt material, and this processing is time consuming and expensive.
(2) Cross section deficiency and stress concentration occur in the threaded portion of the bolt material that has been machined, resulting in a decrease in yield strength.
(3) It takes time to mount the bearing plate with nuts with screws.
(4) It takes time to cut the protruding portion of the head of the bolt material.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to propose a lock bolt that is excellent in workability and economical efficiency without reducing the proof strength of the bolt material.

  In order to solve such a problem, the invention according to claim 1 includes a bolt member inserted into the ground, and a bearing plate that is integrally joined in advance to the head end of the bolt member. This is a featured lock bolt.

  Such a lock bolt has a bearing plate mounted in advance so that the tip of the head does not protrude in the longitudinal direction at the tip of the head of the bolt material. Since the trouble of attaching the plate is saved and the protruding portion is not formed, for example, the trouble of attaching a plastic cap or a nonwoven fabric for preventing damage to a waterproof sheet required for a lock bolt in normal tunnel construction or disclosed in Patent Document 1 Therefore, it is possible to shorten the construction time because the labor of cutting the protruding portion of the bolt material head performed after inserting the lock bolt is omitted. In addition, since the materials, machines, labor costs, etc. required for these operations can be reduced, construction costs can also be reduced.

  The invention according to claim 2 is the rock bolt according to claim 1, wherein the bearing plate is formed of a flat steel plate, the bolt material is formed of a deformed reinforcing bar, and the bearing plate and the bolt material are It is characterized by being integrated by friction welding.

  These lock bolts maintain the breaking strength of each steel material by integrating a flat steel plate that has not been drilled or otherwise processed into a deformed reinforcing bar that has not been processed by screw processing or the like by friction welding. Therefore, since it can be used as a support work, it is possible to construct a support structure that is superior in yield strength compared to conventional lock bolts. In addition, it is possible to save the trouble of performing screw processing on the deformed reinforcing bar or processing to make a hole in the flat steel plate, and it is possible to reduce the cost required for these processing.

  The invention according to claim 3 is the rock bolt according to claim 2, wherein a corner portion of the bearing plate formed of the flat steel plate is bent toward the bolt material.

  In such a lock bolt, since the corner portion of the bearing plate is bent toward the bolt material side, the bearing plate is fixed in such a manner that the bearing plate bites the shotcrete. With this configuration, it is possible to more firmly integrate the lock bolt and the shotcrete concrete, and the structure is such that transmission of mutual force is more effectively performed.

  According to the lock bolt of the present invention, since the bolt material and the bearing plate are integrally formed in advance and the head portion of the bolt material does not protrude from the bearing plate, the bolt head protection member such as a plastic cap or a nonwoven fabric is attached. This saves labor and labor for cutting the projecting portion and shortens the construction time. In addition, since the materials, machines, labor costs, etc. required for these operations can be reduced, construction costs can also be reduced. Furthermore, since the force transmission is effectively performed while the breaking strength of each steel material is maintained, it is possible to construct a tunnel structure that is superior in strength compared to conventional lock bolts.

DESCRIPTION OF EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.
Moreover, in the following description, the case where the lock bolt of this invention is used for the support work of a tunnel is illustrated. Further, in this specification, “inside and outside” means that the inside of the tunnel is “inside” and the opposite is “outside” with reference to the inside of the tunnel. The “head” in the lock bolt indicates the end of the bolt material in the inner direction of the tunnel.

<First Embodiment>
FIG. 1 is a cross-sectional view illustrating a state in which a lock bolt according to a first embodiment (hereinafter may be referred to as “first embodiment”) is installed, and 1 denotes the lock bolt. FIG. 2 is a perspective view showing the entire lock bolt 1.

  The lock bolt 1 used in the first embodiment is a lock bolt based on the entire surface fixing system, and as shown in FIG. 2, a bolt bolt 2 made of deformed reinforcing bars having a predetermined diameter and length, A bearing plate 3 made of a flat steel plate having a square shape is integrated by friction welding S.

Next, a tunnel construction method using the lock bolt 1 of the present invention will be described.
(1) Spray concrete 7 is sprayed on a tunnel wall surface excavated with a predetermined length.
(2) After spraying the shotcrete 7, the rock bolt insertion hole 4 is drilled in the ground G of the tunnel with a drill jumbo or the like (not shown).
(3) The fixing material 5 made of mortar grout or the like is filled in the lock bolt insertion hole 4.
(4) The lock bolt 1 is inserted into the lock bolt insertion hole 4 from inside the tunnel by human power or a drill jumbo drifter.
(5) The backfill mortar 6 is packed in the gap between the bearing plate 3 of the rock bolt 1 and the surface of the shotcrete 7.
Here, in the backfill mortar 6 packed between the bearing plate 3 and the shotcrete 7, the surface of the shotcrete 7 is not constant and is uneven, so that the lock bolt 1 and the shotcrete 7 are integrated. This is done for the purpose of improving familiarity.
(6) The steps (1) to (5) above are repeated to install a predetermined number of lock bolts, and the waterproof sheet 8 is attached to the inner surface of the tunnel at the location where the tunnel excavation is completed.
(7) Placing the lining concrete 9 using a mold such as a slide centle (not shown).

  Thus, since the installation is completed without using a nut, the lock bolt 1 is excellent in workability. Further, when the lock bolt 1 is manually installed, the bearing plate 3 is installed in advance on the bolt material 2, so that there is an advantage that it is easy to push in.

Further, as shown in FIG. 1, the lock bolt 1 is formed by drilling the lock bolt insertion hole 4 on the inner wall surface of the tunnel where the shotcrete 7 is sprayed, and the lock bolt 1 is filled with the fixing material 5 made of mortar grout. It is inserted into the lock bolt insertion hole 4 and fixed.
With this structure, the lock bolt 1 can be integrated with the shotcrete 7 and a supporting structure required for tunnel construction can be constructed.

  In addition, conventional lock bolts tend to be considered to exert the effect of the lock bolts by tightening the bearing plate using nuts, but in reality, the bearing plate is installed before the fixing material solidifies. Therefore, after the bolt material and the bearing plate are installed, the fixing material is solidified and the effect of the fixing material appears. Therefore, even the lock bolt according to the first embodiment can provide the effects of the conventional lock bolt.

  Moreover, since the lock bolt 1 forms a flat surface by the bearing plate 3 installed at the tip of the head, in the installation work of the waterproof sheet 8 to be installed at the time of placing the lining concrete 9, Since there is no projecting part, there is no need for processing such as installation of plastic caps or non-woven fabrics, cutting of projecting parts of the bolt material 2, and there is no work of attaching nuts for installing the bearing plate 3, resulting in excellent workability. ing.

Further, since the bearing plate 3 and the bolt material 2 are joined by friction welding S, it is not necessary to perform special processing on each steel material, and the cost required for the steel material processing can be reduced.
Further, since the cross section of the deformed reinforcing bar is not reduced by the amount of screw processing on the head of the bolt material 2, a tunnel having excellent strength is constructed without reducing the proof strength of the deformed reinforcing bar. Can do.

<Second Embodiment>
FIG. 3 is a cross-sectional view showing a state in which a lock bolt according to a second embodiment (hereinafter sometimes referred to as “second embodiment”) is installed, and 1 ′ denotes the lock bolt. FIG. 4 is a perspective view showing the entirety of the lock bolt 1 ′.

  The lock bolt 1 ′ used in the second embodiment is a lock bolt based on the entire fixing method, and as shown in FIG. 4, at the head end of the bolt material 2 made of a deformed reinforcing bar having a predetermined diameter and length, A bearing plate 3 ′ formed by bending four corners 3 a of a substantially square flat steel plate to the bolt material 2 side at a predetermined angle is integrated by friction welding S.

  In addition, since the tunnel construction method using the lock bolt 1 'of the second embodiment is the same as the tunnel construction method shown in the first embodiment, detailed description thereof is omitted.

  As shown in FIG. 3, since the corner 3 a of the bearing plate 3 ′ is bent toward the bolt member 2, the corner 3 a is inserted into the shotcrete 7 when inserted into the lock bolt insertion hole 4. Fixed in a fixed state. With this configuration, the lock bolt 1 ′ and the shotcrete 7 are firmly integrated, and a support structure with excellent mutual force transmission is constructed.

  Further, since the corner 3a of the bearing plate 3 'installed at the tip of the head of the lock bolt 1' is bent toward the bolt material 2, the corner 3a of the bearing plate 3 'is directly attached to the waterproof sheet 8. Never hit. Therefore, it becomes possible to prevent damage to the waterproof sheet 8 due to the waterproof sheet 8 being caught on the corner 3a during construction or some pressure being applied to the contact portion between the corner 3a and the waterproof sheet 8. This makes it possible to construct tunnels with excellent water-stopping properties.

  In addition, since the effect which the lock bolt 1 'of another 2nd embodiment show | plays is the same as that shown in 1st Embodiment, detailed description is abbreviate | omitted.

As mentioned above, although preferred embodiment was described about this invention, this invention is not limited to said each embodiment, A design change is possible suitably in the range which does not deviate from the meaning of this invention.
For example, the bolt material and the bearing plate are joined by friction welding. However, the invention is not limited to this, and it is possible to join without reducing the proof stress of the bolt material, such as welding joining. For example, the joining method is not limited.
Further, in each of the above embodiments, a deformed reinforcing bar is used as the bolt material, and a flat steel plate is used as the bearing plate. However, the present invention is not limited to this. For example, a twisted steel rod is used as the bolt material, a round shape, The material and shape are not limited as long as they can function as a lock bolt, such as using a polygonal flat steel plate as a bearing plate, and the bolt material and the bearing plate can be integrated. .

Further, in each of the above embodiments, the lock bolt is used for the lock bolt based on the entire fixing method. However, the present invention is not limited to this, and the lock bolt fixing method according to the condition of the natural ground, such as a combination method, is not limited thereto. May be adopted.
In each of the above embodiments, the fixing material is filled into the lock bolt insertion hole before the lock bolt is inserted. However, the fixing material may be filled after the lock bolt is inserted into the lock bolt insertion hole. If possible, the construction order is not limited.
In each of the above embodiments, mortar grout is used as a fixing material for a rock bolt. However, the material is not limited to this as long as the material exhibits sufficient fixing power. Absent.

In each of the above embodiments, the rock bolts are installed after the spraying work of the shotcrete is completed. After performing early closing of the cross section by attaching, a lock bolt may be installed, and then secondary spraying may be performed to further enhance the integration of the support structure.
For high-quality rocks that do not require shotcrete, rock bolts may be installed directly on the wall of the tunnel that has been excavated with a predetermined digging length so as to be integrated with the ground.
Furthermore, the lock bolt of the present invention is not limited to the lock bolt used in tunnel construction, and can be used for, for example, slope restraining work.

It is sectional drawing which shows the state which installed the lock bolt concerning 1st Embodiment. It is the perspective view which showed the whole lock bolt concerning 1st Embodiment. It is sectional drawing which shows the state which installed the lock bolt concerning 2nd Embodiment. It is the perspective view which showed the whole lock bolt concerning 2nd Embodiment. It is sectional drawing which shows the condition which installed the lock bolt of patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 'Rock bolt 2 Bolt material 3, 3' Bearing plate 3a Corner part 4 Lock bolt insertion hole 5 Fixing material 6 Backing mortar 7 Shotcrete 8 Waterproof sheet 9 Covering concrete G Ground S Friction welding

Claims (3)

  A lock bolt comprising: a bolt material inserted into the ground; and a bearing plate that is integrally joined to a tip of the head of the bolt material in advance.   2. The bearing plate according to claim 1, wherein the bearing plate is formed of a flat steel plate, the bolt material is formed of a deformed reinforcing bar, and the bearing plate and the bolt material are integrated by friction welding. The described lock bolt.   The lock bolt according to claim 2, wherein a corner portion of the bearing plate formed from the flat steel plate is bent toward the bolt material side.

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