JPH0458560B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention is applicable to excavation works such as tunnels, etc.
Concerning the rock bolt construction method for reinforcing the ground.

《Prior art and its problems》 In civil engineering works such as tunnel construction, lock bolts with axial tensile strength are inserted and buried in the excavated part along with hardening materials such as mortar to prevent the surrounding ground from collapsing or peeling. However, construction methods that improve the physical properties of the ground are being adopted.

As the lock bolts used in these construction methods, rigid bodies such as steel bars, deformed steel bars, and fiber-reinforced plastic rods are conventionally used.

On the other hand, the advantage of the rock bolt construction method is that it allows for a larger excavation length per cycle compared to conventional construction methods. From this point of view, the longer the length of the rock bolt, the greater the reinforcement of the ground, and the greater the benefits. Recently, high-precision rock drilling machines such as leg drills and drifters that can drill long holes have been developed, but attempts were made to insert the aforementioned rigid rock bolts with a length of 3 to 4 meters into the hole drilled by these machines. As a result, the drilled hole itself was bent and displaced, making it difficult to drive the lock bolt smoothly.

As a construction method that can overcome these problems, the applicants of this case have developed a lock bolt construction method that can be inserted following a long drilled part in patent application No. 59-161309 (Japanese Patent Publication No.
It has already been proposed in Publication No. 49358).

The construction method according to this application uses a flexible synthetic resin lock bolt with a rope-like structure made of a fiber-reinforced thermosetting resin composite material, and includes a first step of filling the drilled hole with a self-hardening material; The second step is to insert the lock bolt into the hole filled with hard material.

The synthetic resin lock bolt described above can be inserted following the bending displacement of the drilled part or against the filled self-hardening material, and the anchor anchoring force is due to the uneven structure of the strands on the outer periphery of the rope-like structure. This is achieved by the effective locking force of the anchor, and has sufficient performance for use in temporary construction.

On the other hand, when this lock bolt is used for construction work that supports a layer of shotcrete, etc., a fixing fitting is required to fix the end of the lock bolt to the ground, and this fixing fitting is also capable of maintaining the tensile strength of the lock bolt itself. There must be.

However, a fixing fitting suitable for this type of rope-shaped lock bolt that satisfies these requirements has not yet been developed, and if the conventional method was applied as is, the characteristics of the lock bolt described above would not be fully demonstrated. .

The present invention has been made in view of the above-mentioned problems, and uses a flexible lock bolt with a fixing fitting fixed to the head of the casting side in advance, and inserts it into a drilled hole using the flexible lock bolt. The purpose is to provide a construction method that supports the surface layer of the ground.

<<Means for solving the problems>> In order to achieve the above object, the structure of the present invention is as follows:
As stated in the claims, to summarize, a hole for inserting a lock bolt of approximately 1.5 to 2D relative to the diameter D of the lock bolt is drilled in the ground using a rock drill such as a leg drill or a drifter. After drilling, mortar or a self-hardening material such as unsaturated polyester resin or epoxy resin is filled into the hole using a compressor or pump, and the outer periphery of the fiber-reinforced thermosetting resin is then covered with thermoplastic resin. A flexible lock bolt consisting of a lock bolt body with a spiral rope-like structure made of a strand covered with a strand and a cylindrical fixing fitting fixed to the lock bolt body in advance is driven and inserted against a self-hardening material, and then It consists of a step of tightening the seat plate with a nut so that the seat plate is sandwiched between the backing pile and the cylindrical fixing metal fitting.

In particular, the present invention is characterized by the structure of the lock bolt and the method of fixing the fixing fitting to the driving side head thereof, so these will be described in detail.

First, the lock bolt body used in the present invention is
Thermosetting resin materials such as uncured unsaturated polyester resins and epoxy resins, glass fibers, aromatic polyamide fibers, carbon fibers, polyester fibers,
The core material is made by impregnating a reinforcing fiber bundle with high strength, low elongation, and strong retention properties such as vinylon fiber, and shaping it into a circular shape. Various polyethylene, ethylene-vinyl acetate copolymers, and various nylon , various
A thermoplastic resin such as ABS resin or various types of polypropylene is extruded and coated in a ring shape, and then the coated portion is cooled to obtain an uncured composite strand.

This composite strand is supplied to a twisting machine, and a plurality of uncured composite strands are spirally wound around the outer periphery of one strand at a predetermined pitch to obtain an uncured spiral rope-like object. Pass it through a heating tank to harden the thermosetting resin inside to obtain a spiral rope-shaped lock bolt body. During this curing, the curing temperature, thermosetting resin material, curing catalyst, thermoplastic resin, etc. are selected so that the thermoplastic resin of each composite strand can be fused and bonded to adjacent strands. This is very important.

This hardened spiral roll lock bolt body is cut to a predetermined length, and a fixing fitting having the following structure is fixed to the driving side head.

First, the fixing metal fitting is mainly made of a cylindrical steel material of an appropriate length with screws machined on the outer periphery, and the inner diameter of the inner cylinder part is large enough to accommodate the outer periphery strand of the spiral rope lock bolt by expanding it. The upper end side has a reduced diameter portion corresponding to the apparent outer diameter of the rope-shaped lock bolt. Furthermore, a ring wedge having a tapered portion on the insertion progressing side is used to expand the above-mentioned outer circumferential strand.

Prepare these fixing fittings and ring wedges,
The thermoplastic resin coating layer is peeled off from the end of the rope-shaped lock bolt that fixes the fixing metal fitting, thereby making it possible to improve the adhesive strength and expand the outer strand.

After making the various preparations in this way, as shown in Figure 2, the cylindrical fixing metal fitting is fixed with adhesive while the outer strand of the spiral rope lock bolt is expanded using the ring wedge. hand,
This is a lock bolt used in the construction method of the present invention.

The second step is to insert the lock bolt into the hole filled with a self-hardening material, and at the same time or after the self-hardening material has hardened, an appropriate seat plate is fitted onto the cylindrical fixing metal fitting. The third step consists of bringing the fixing fitting into contact with the ground using a nut screwed onto the outer periphery of the fixing fitting.

"Example" Preferred embodiments of the present invention will be described below.

First, a 1×7 type spiral rope lock bolt was prepared as follows.

For the strand of the rope-shaped lock bolt, glass roving was impregnated with uncured unsaturated polyester resin, and this was shaped to obtain an uncured bar with an outer diameter of 6.5 mm, which was then inserted into a crosshead die. The strands were coated with high-density polyethylene to an outer diameter of 7.2 mm and immediately cooled to form a strand of primary coating, which was then inserted again into the crosshead die and mixed with ethylene vinyl acetate with a vinyl acetate content of 15%. A composite strand with an outer diameter of 7.7 mm was obtained by the polymer.

This is fed to a twisting machine, and six strands are arranged in a spiral around the outer circumference of one core strand.
A 1 x 7 type rope with a twist pitch of 225 mm was obtained, and this was passed through a heating tank at 98°C to cure the unsaturated polyester resin inside the strand, while the ethylene vinyl acetate copolymer on the outer periphery of each strand was cured. The coatings were fused and bonded together to obtain a rope-shaped lock bolt body 2 composed of outer strands with an apparent outer diameter of 23 mm, a unit weight of 510 g/m, and a tensile strength of about 18 tons. This lock bolt body 2
As schematically shown in FIG. 1b, the cross-sectional shape is composed of a composite strand in which the outer periphery of a core material 4 made of a fiber-reinforced synthetic resin is covered with a thermoplastic resin.

This lock bolt body 2 was cut into 4 m lengths, and the thermoplastic resin coating on one end thereof was peeled off over a length of 150 mm to make each strand movable.

Next, a cylindrical fixing fitting 3 having a length of 150 mm and having a reduced diameter part 7 with an inner diameter of 23 mm and a thickness of 10 mm, an inner cylindrical part 8 with an inner diameter of 26 mm, and an outer periphery 9 with M36 threads with a pitch of 4 mm are attached to the above-mentioned coating. Fit the peeled part side externally, and then attach the upper part 4 with an inner diameter of 9 mm, an outer diameter of 12 mm, and a total length of 10 mm.
For the section of mm, insert the core strand 11 through the tapered ring wedge 10, place it at a position 75 mm from the end where the coating has been peeled off, and spread the outer strands 12, 12..., and then , the cylindrical fixing metal fitting 3 is returned to a predetermined position, and the lower end of the fixing metal fitting 3 is sealed with butyl tape.

After that, apply epoxy adhesive (Konishi Co., Ltd.)
A mixture of 100 parts of CL-60), 15 parts of hardening agent, and 20 parts of calcium carbonate is mixed with 1 part of filled adhesive resin.
3, and injected this from the reduced diameter part 7 side of the cylindrical fixing fitting 3 set on the rope-shaped lock bolt,
The interior of the fixing metal fitting 3 is filled with adhesive filler resin 13, which is cured at room temperature and then further cured at 80°C to integrate the fixing metal fitting 3 and the lock bolt main body 2.
As shown in the figure, a rope-shaped lock bolt 1 was obtained.

This lock bolt 1 is inserted into the ground 16 in which the drilled part 14 with a hole diameter of 36 mm is filled with mortar 15, and a flat washer 17 with a size of 150 x 150 mm and a thickness of 12 mm is placed on the fixing fitting 3 side.
It was clamped by the nut 18 of M36 and brought into contact with the earth 16.

The pulling force of the lock bolt 1 constructed in this manner was measured for five samples. As a result, the pulling force was 16 to 18 tons, or strong enough to destroy the threaded portion 9, and the locking bolt body 2, which has a substantially rope-like shape, exhibited a strong fixing force.

- Comparative example Using the same lock bolt body 2 as the example,
A lock bolt with the same conditions except that it does not have the reduced diameter part 7 and the ring wedge 10 was manufactured as a prototype, and after driving it into the earth 16 under the same conditions as in the above example, its pulling strength was measured, which was 5 to 7 tons. I was able to obtain only moderate values.

《Effects of the Invention》 As explained above, the lock bolt construction method of the present invention has a spiral rope-like structure in which composite strands made of fiber-reinforced thermosetting resin and thermoplastic resin are twisted together. The lock bolt body has compressive elasticity that allows it to be inserted against the self-hardening material filled in the area, and the lock bolt has a fixing fitting configured to exert high fixing force. It is long, and even if there is a bending displacement, it is possible to insert and cast by following this bending displacement, and at the same time, a seat plate is fitted onto the fixing fitting on the pouring side head, and this seat plate is attached to the ground side. By bringing it into contact with a nut screwed onto the fixing fitting, it is possible to reliably support the surface layer of the ground, such as a shotcrete layer.

Further, according to this construction method, since it is possible to use a relatively long lock bolt, it is possible to extend the excavation length per cycle in tunnel construction, and the construction period can be shortened.

[Brief explanation of drawings]

Fig. 1a is a side view showing an example of the lock bolt used according to the present invention, Fig. 1b is a cross-sectional view thereof, and Fig. 2 is a schematic diagram showing the state of connection between the fixing fitting fixed to the lock bolt of the present invention and the lock bolt main body. figure,
FIG. 3 is a schematic diagram showing an example of construction completed using the construction method of the present invention. DESCRIPTION OF SYMBOLS 1... Lock bolt, 2... Lock bolt body, 3... Fixing metal fitting, 6, 11... Core strand, 7... Reduced diameter part, 9... Screw, 10... Ring wedge, 12... Outer periphery strand, 13 ... Filled resin for adhesion, 14 ... Hole drilling, 15 ... Mortar, 16
...Jiyama, 17...Zaita, 18...Natsuto.

Claims (1)

[Claims] 1. The first step is to fill a self-hardening material that will become an anchor body into a hole drilled in the ground, and the second step is to insert a lock bolt with a fixing fitting fixed in advance into the hole filled with the self-hardening material as a tensile reinforcing material. A lock bolt construction method comprising the steps of (1) and (3) a third step of fitting a seat plate onto the fixing metal fitting of the lock bolt and sandwiching the seat plate between the earth and the fixing metal fitting, the lock bolt construction method comprising: A lock bolt is comprised of a plurality of strands made of fiber-reinforced thermosetting resin coated with thermoplastic resin, and includes a spiral rope-shaped lock bolt body in which adjacent thermoplastic resins of each strand are fused together, and It consists of a cylindrical fixing metal fitting that clamps and fixes the separated outer periphery strand in the head part of the casting side of the main body in such a way as to expand it, and this locking bolt is inserted into the drilled hole, and at the same time or when the self-hardening material hardens. The lock bolt construction method is characterized in that, in the third step, the seat plate is clamped by screwing a nut around the outer periphery of the cylindrical fixing metal fitting.