JP2517918Y2 - Rock bolt for civil engineering - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a civil engineering rock bolt, and more specifically, to the end of a long deformed steel bar that is inserted into a hole formed in rock to secure a tunnel support, etc. The present invention relates to a rock bolt for forming a civil engineering work.

[0002]

[Prior Art] In civil engineering work such as forming tunnels,
Temporary structures are often assembled by columns, frame columns, and assembled steel columns. When a tunnel is formed in a hard ground such as rocky ground, a supporting structure is used to fix those structures to the rocky ground. In the new australian tunnel construction methods such as tunnel support work, rock swell prevention method for expansive tunnels, side wall form stop, earth retaining anchor, etc. A long rebar material with a screw made of steel bars or the like is inserted, and is used in large numbers as a securing member for tunnel support work. As such a lashing member, FIG.
The lock bolt 20 as shown in FIG. In this lock bolt 20, a threaded portion 26 is formed at the end of a long base metal rebar 25 such as a deformed steel bar. Most of the base material reinforcing bar 25 is the drilled hole 2 formed in the bedrock 24.
2 and resin or mortar around the base material reinforcing bar 25
3 is packed. If the mortar 23 or the like solidifies, the washer 28 is attached to the screw portion 26 that appears from the drilled hole 22 to the outside of the rock mass.
The tunnel support 27 and the like can be firmly fixed to the bedrock 24 by fitting the nuts 29 and fitting them. Such a lock bolt 20 is manufactured based on a base metal rebar 25 made of one deformed steel bar.
That is, the threaded portion 26 is formed by machining or rolling one end of the deformed steel bar that has been cut into a predetermined length in advance.

[0003]

In order to form the above-mentioned threaded portion 26, since a long base metal rebar 25 is gripped and processed, a large-scale apparatus is required for the processing. Since it is long, centering work becomes complicated,
There are drawbacks such that it is not easy to improve the processing accuracy of the screw portion 26. On the other hand, in order to form the threaded portion 26, it is necessary to scrape off the ribs 25a extending in the axial direction of the deformed steel bar and the joints 25b formed in the circumferential direction. There is no choice but to make the diameter smaller than the diameter of the surface 25c of the reinforcing bar 25. The thread portion 26 is of course the same steel quality as the base material rebar 25, and since its cross section is small, the mechanical strength of the thread portion 26 is the same as that of the base material rebar 25 in the unprocessed portion. It is inferior to the target strength. Therefore, although a carbon structural steel having a high tensile strength such as SD345 defined by JIS is adopted as the base metal rebar, there is a problem that the threaded portion 26 having a small cross section is easily broken or sheared. . On the contrary, in order to secure desired strength in the threaded portion 26, it is necessary to adopt a base material rebar 25 having a large diameter, and the long portion into which the drilled hole 22 is inserted has an excessive cross-sectional proof strength. It will be a lock bolt that you have. Not only that, but also the diameter of the perforation hole 22 formed in the bedrock 24 becomes large, which increases the burden of the perforation work. As the perforation hole 22 becomes larger, the consumption amount of the mortar 23 to be filled also increases,
There is a problem that promotes uneconomical. In addition, the heavy-duty rock bolt is handled in a narrow tunnel, which necessitates a reduction in handling and workability.

The present invention has been made in view of the above problems, and an object thereof is to provide a deformed steel bar having an excessive strength by adopting a base metal rebar having a desired diameter suitable for fixing a tunnel support or the like to rock. The consumption can be reduced, the diameter of the drilled hole can be reduced to reduce the drilling work, the amount of mortar used can be reduced, and the threaded portion that matches the strength of the base metal rebar can be easily provided. It is possible to provide a rock bolt for civil engineering, which realizes that it is possible to improve the processing accuracy of its threaded portion.

[0005]

According to the present invention, a thread portion is provided at an end portion of a base material rebar such as a deformed steel bar, and most of the base material rebar is inserted to fix a support for a tunnel or the like. It is applied to a long steel bar for civil engineering, in which a fixing nut is engaged with the above-mentioned screw portion that appears from the drilling hole to the outside of rock mass. The feature is that it is shown in FIG.
Referring to, the rear end face 2a of the base metal rebar 2 inserted into the drilled hole 6 has a front end face 3 of a rear end ferrous member 3 separately manufactured.
a is connected, and the rear end iron material 3 is formed with a screw portion 4 having a mechanical strength higher than that of the base material reinforcing bar 2. The threaded portion 4 formed on the end iron material 3 is
Whether the root diameter of the screw is made larger than the outer diameter of the base metal rebar 2 or a different steel type having a mechanical strength larger than that of the base metal rebar 2 is used as the rear end iron 3 and the rear end iron 3 is The diameter of the formed screw may be approximately equal to the outer diameter of the base material reinforcing bar 2 (see FIG. 2). The base material reinforcing bar 2 and the rear end iron material 3 can be connected by friction welding or by flash butt.

[0006]

The deformed steel bar having a diameter capable of withstanding the loads such as tension, shear, and bending of the lock bolt 1 predicted in the construction is selected as the base metal rebar 2. Apart from the base material reinforcing bar 2, a screw part 4 is formed on an iron material having a mechanical strength higher than that of the base material reinforcing bar 2.
The trailing edge iron material 3 is manufactured. The rear end iron material 3 may be significantly shorter than the base material rebar 2, and the threaded portion 4
The forming process is much easier than when forming on one end of the base material reinforcing bar 2. The threaded portion 4 is selected such that the root diameter of the screw is larger than the outer diameter of the base material rebar 2, or different steel types having mechanical strength larger than that of the base material rebar 2 are adopted. In the latter case, the screw diameter is set to be approximately equal to the outer diameter of the base metal rebar 2. Rear end face 2a of base material rebar 2
Is connected to the front end surface 3a of the rear end iron material 3 by welding, friction welding, flash butt, or the like to form one long civil engineering rock bolt 1. A drill hole 6 having a diameter slightly larger than that of the base metal reinforcing bar 2 is formed in the rock mass 8 of the tunnel, and most of the base metal reinforcing bar 2 is inserted therein. Screw part 4
Is a state where it appears from the drill hole 6 to the outside of the rock mass 8, and the base material rebar 2 is fixed to the drill hole 6 by a mortar 7 or the like. For example, if the tunnel supporter 12 is attached to the screw portion 4 and the fixing nut 5 is engaged with the screw portion 4, the tunnel supporter 12 is fixed to the bedrock 8. The base metal rebar 2 has a thickness sufficient to fix the tunnel support 12 and the like, and the mechanical strength formed on the rear end iron 3 is high even if a deformed steel bar having an excessive diameter is not adopted. The screw portion 4 can sufficiently maintain the fixed state. Therefore, the diameter of the perforation hole 6 may be small, which not only reduces the work of perforation but also saves the consumption of the mortar 7 or the like to be filled. The screw part 4 can process the short rear end iron material 3 separately from the base material rebar 2, and the high precision of the screw can be easily obtained, exerting a large fastening force and realizing a reliable fixed state. can do.

[0007]

According to the lock bolt of the present invention, it is possible to employ a long-length base metal rebar inserted into a hole, which has a desired size, regardless of the diameter of the threaded portion. . Therefore, it is possible to avoid using an oversized deformed steel bar, reduce the weight of the lock bolt, facilitate handling in a narrow tunnel, and improve workability. The diameter of the perforation hole formed in the rock mass may be set to be commensurate with the diameter of the base metal rebar, and therefore the burden in the perforation work is reduced. Further, the consumption of the mortar pre-filled in the drilled holes is reduced, and the tunnel construction can be made inexpensive. The rear end iron material can be selected such that its diameter dimension or material is not limited by the diameter of the base material reinforcing bar, so as to meet the mechanical strength required for the base material reinforcing bar. Moreover, since it is sufficient to form it on the short rear end iron material, the threading operation can be remarkably easy and a highly accurate product can be obtained. This makes it possible to exert a large fastening force. The rear-end iron material having the threaded portion is simply connected to the base metal rebar by subsequent welding, friction welding, flash butt, or the like.
Therefore, there is almost no need to modify the base metal rebar, and by preparing various rear end iron materials of desired diameter or steel quality, it is possible to quickly prepare lock bolts according to the specifications of the construction. it can.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The lock bolt of the present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is a mounting view showing the lock bolt 1 according to the present invention as a whole and a state of being fixed to a drill hole 6 formed in a rock 8. A base metal rebar 2 made of deformed steel bar and the base metal rebar It is composed of a rear end iron material 3 attached to the end portion of 2. A threaded portion 4 to be described later is formed in the end iron material 3, and the rock 8
The tunnel support work 12 and the like can be fixed. The base material rebar 2 having a cross-sectional dimension that exerts the strength required for tunnel construction is adopted, and it is not restricted by the size of the screw portion 4 required for fixing the rock bolt 1 to the rock 8 and is excessive. Those that do not have a large thickness are adopted. The deformed steel bar is manufactured by hot rolling carbon structural steel such as SD345, and has a large number of ribs extending in the axial direction and nodes surrounding the circumferential direction on the outer surface thereof. The shapes of these ribs and the like differ depending on the deformed steel bar, but in any case, when they are inserted into the drilled holes 6, the unevenness formed by the ribs or joints ensures close contact with the mortar and functions as a lock bolt. Is strongly fixed in the drilled hole 6. In addition, most of the long base material rebar 2 that constitutes the lock bolt 1 is inserted into the perforation hole 6, the screw portion 4 formed on the rear end iron material 3 appears outside the bedrock 8, and the fixing nut is used. 5 is engaged.

The rear end iron material 3 is formed with a screw portion 4 having a mechanical strength higher than that of the base material reinforcing bar 2. When the rear end iron material 3 is of the same steel quality as the base material rebar 2, the rear end iron material 3 is provided with a screw portion 4 having a root diameter larger than that of the base material rebar 2. When the material is different and has a high tensile strength, as shown in FIG. 2, a material having substantially the same diameter as the base material reinforcing bar 2 is used. Then, the threaded portion 4 is formed by machining such as cutting or rolling with the rear end iron material 3 itself being alone. In this way, the front end surface 3a of the rear end iron material 3 produced independently is butted against the rear end surface 2a of the base metal rebar 2, and is connected by welding to be integrated. The connection can also be by friction welding or flash butt. In the friction welding, the rear-end iron material 3 and the base metal rebar 2 are butted and relatively rotated while being pressed, and the friction heat generated at the contact surface is used to join the both.
In the case of a flash bat, the base metal rebar 2 is clamped to the movable electrode and the rear end iron 3 is clamped to the fixed electrode, a local arc is generated on the contact surface while applying a voltage, and both are melted and scattered by the arc, so-called flushing. Are connected.

As described above, a strong connection state can be obtained by any of the connection methods such as welding, friction welding, and flash butt, but in consideration of ensuring an appropriate size of the abutting surfaces, the rear end iron material Even if 3 has a higher tensile strength than the base metal reinforcing bar 2, the front end surface 3 of the rear end iron 3
It is preferable that the cross-sectional area of a is substantially equal to that of the rear end surface 2a of the base metal reinforcing bar 2. Therefore, the rear end iron material 3 may have a diameter substantially the same as that of the base material rebar 2. An appropriate amount of mortar 7 or resin has been previously injected into the above-mentioned drill hole 6, and the lock bolt 1 is inserted into the drill hole 6 so as to push the liquid mortar 7 having a high viscosity, etc. At the front end of the iron material 3, a driving portion 3b smaller than the diameter of the screw portion 4 is formed. The driving portion 3b is also formed when the screw portion 4 is processed. The driving portion 3b is a portion to be hit by a hammer or the like, and has a cross-sectional size smaller than the root diameter of the screw so that the screw portion 4 is not affected even if it is slightly deformed. On the other hand, the tip 2b of the base metal rebar 2 is formed into a conical shape in the shape of a barb so that the lock bolt 1 can easily enter the hole 6.

With the lock bolt 1 having such a structure, the tunnel support structure 12 for a temporary frame structure or the like installed on the inner surface of the tunnel can be securely fixed to the rock mass 8 in the following manner. When the specifications of the lock bolt 1 used for tunnel construction are determined, the base material rebar 2 having a material and a diameter satisfying the tensile load, the shear load, the bending load, and the like suitable for the lock bolt 1 is selected. At that time, without considering the strength of the threaded portion 4, a deformed steel bar having a suitable diameter required only for the base material reinforcing bar 2 is used. On the other hand, as the rear end iron member 3 connected to the rear end face 2a of the base metal reinforcing bar 2, an iron member having a diameter that satisfies the strength required for the screw portion 4 formed therein is selected. When the rear-end iron material 3 has the same steel quality as the base material reinforcing bar 2, a large diameter iron material is used so that the cross-sectional proof stress of the threaded portion 4 is equal to or higher than the cross-sectional proof strength of the base metal reinforcing bar 2. When a material having a higher tensile strength than that of the base metal rebar 2 is used, an iron material having the same diameter as the diameter of the base metal rebar 2 is selected.

In the rear end iron material 3, the screw portion 4 is formed separately from the base material reinforcing bar 2. And the rear iron material 3
3 is abutted against the rear end surface 2a of the base metal rebar 2 and connected by welding, friction welding or flash butt. The rock 8 exposed on the inner surface of the tunnel has a hole 6 slightly larger than the diameter of the base metal rebar 2.
An appropriate amount of mortar 7 or resin is injected therein. The lock bolt 1 is inserted into the drilled hole 6 and the base metal rebar 2
Is hit on the driving part 3b so that the most part of it enters the hole 6.
The lock bolt 1 enters so that the tip 2b separates the mortar. The screw portion 4 is left outside the bedrock 8 and waits for the mortar 7 to solidify. Base material rebar 2
At the time point when the structure is fixed to the bedrock 8, the tunnel support 12 for forming the temporary structure in the tunnel is arranged so that the bolt hole 12a formed therein fits into the screw portion 4. When a plate material 11 such as a washer is inserted and the fixing nut 5 is tightened, the tunnel support 12 is fixed to the bedrock 8 via the screw portion 4 with high manufacturing accuracy, and a frame body or the like can be assembled or fixed thereto. it can.

As can be seen from the above description, since the base material rebar having the minimum necessary diameter can be used as the lock bolt, use of a deformed steel bar having an excessive size is avoided. The weight of the lock bolt can be reduced, and it can be easily handled in a narrow tunnel. The size of the perforation hole may be suitable for the base material rebar, the burden of the perforation work is reduced, and the consumption of mortar or the like injected into the perforation hole is small. Since the threaded portion can be formed on the rear end iron material independently of the base material rebar, the threaded portion can be easily processed and the manufacturing accuracy thereof can be increased. Therefore, smooth fastening work and reliable fixing are achieved, and at the same time, reduction of construction costs such as assembling the frame in the tunnel is promoted. In the above description, the fixing of the tunnel support work is taken as an example, but the lock bolt according to the present invention is used for the new australian method such as the method for preventing swelling of expansive tunnels, side wall formwork fixing, and earth retaining anchors. It can be used for fixing assembled steel columns and the like in tunnel construction methods and other construction methods.

[Brief description of drawings]

FIG. 1 is an explanatory view of the entire rock bolt including a rear-end iron material in which a threaded portion having a diameter larger than that of a base material reinforcing bar is formed and a construction state.

FIG. 2 is a main part view of a lock bolt in which a threaded portion is formed on a rear end iron material having a steel quality different from that of the base metal reinforcing bar in a construction state.

FIG. 3 is an overall view of a conventional lock bolt and a state of use.

[Explanation of symbols]

2 ... Base material reinforcing bar, 2a ... Rear end surface, 3 ... Rear end iron material, 3a ... Tip surface, 4 ... Screw part, 5 ... Fixing nut, 6 ... Drilled hole, 8
… Bedrock, 12… Tunnel support.

Claims (5)

(57) [Scope of utility model registration request] 1. A base material rebar such as a deformed steel bar is provided with a threaded portion at an end thereof, and a large part of the base material rebar appears to the outside of rock mass for inserting a large portion of the base material rebar for fixing a support for a tunnel or the like. A long rebar material for civil engineering, in which a fixing nut is adapted to be meshed with the threaded portion, the rear end surface of the base metal rebar inserted into the hole is formed separately separately. A rock bolt for civil engineering, wherein a front end surface of an end iron material is connected, and a screw portion having a mechanical strength larger than that of the base material rebar is formed on the rear end iron material. 2. The rock bolt for civil engineering according to claim 1, wherein the threaded portion formed on the rear end iron material has a root diameter of the screw larger than an outer diameter of the base metal rebar. . 3. The rear end iron material is made of different steel having a mechanical strength higher than that of the base material reinforcing bar, and the screw diameter formed in the rear end iron material is substantially equal to the outer diameter of the base material reinforcing bar. The rock bolt for civil engineering according to claim 1, wherein the rock bolt has a size. 4. The rock bolt for civil engineering according to claim 1, wherein the base material reinforcing bar and the rear end iron material are connected by friction welding. 5. The rock bolt for civil engineering according to claim 1, wherein the base material rebar and the rear end iron material are connected by a flash butt.