JP2017172168A - Mushroom-type post-installed anchor, and construction method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mushroom-type post-installed anchor that does not fall out readily even when a vertical load is exerted, as in the case of a ceiling plate collapsing accident in Sasago Tunnel.SOLUTION: A construction method of the present invention includes the following three steps for: forming an expanded bottom part using an under cutter on a bottom part of a hole after drilling the hole; injecting a filler adhesive in a gap between the hole and an anchor deeply into the hole; expanding an anchor body in an anchor form by driving the anchor body after inserting the anchor into the hole. The construction method enables a post-installed anchor to be obtained that hardly falls out, when the entire hole with the bottom expanded in the anchor form is integrated with the anchor by the filler adhesive in a mushroom form, and is adhered firmly on a wall of the hole.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a construction anchor and a construction method after a basic relationship between civil engineering, architecture, and machinery.

  Conventionally, in order to improve the pull-out force of the post-installed anchor, generally, an internal cone driving type, a sleeve type, a wedge type or other expandable metal anchor or a capsule type or cartridge type chemical anchor is used. With the conventional method, if the gravity falls vertically downward as in the case of the December 2, 2012 Chuo Expressway Choshi Tunnel ceiling plate collapse and the Boston Expressway, the possibility of falling off easily It can be said that there is a self-evident reason.

  There are two types of chemical anchors, one that mixes epoxy resin base, hardener, and bone, and one that adds water to cement.

  Epoxy resin adhesives include a capsule method and a cartridge method. In the former, after inserting a capsule containing the main agent, hardening agent, and bone agent into a glass tube or film tube, the capsule is broken by applying a blow to the anchor bolt (full screw bolt) with the tip cut off. Is a type to mix. The latter is a system in which a mixing device is attached to the end of a cartridge in which a main agent and a curing agent are separately packed, and a mixture of the main agent and the curing agent is injected into the hole when in use. The capsule method cannot be mixed sufficiently in a narrow hole, so the original adhesive force of the epoxy resin cannot be expected due to poor mixing. In addition, the latter cartridge system is extremely expensive and disposable, which is economically problematic.

  In view of the above-described problems, the present invention is to obtain a mushroom-type post-installed anchor that does not easily come off even when a load is applied vertically as in the case of the fall of the ceiling plate of the insulator tunnel.

The construction method using a mushroom-type post-construction anchor according to one aspect of the present invention that solves the above problems is as follows.
(1) After drilling a hole with a drill, a step of providing an expanded bottom portion using an undercutter at the bottom of the hole;
(2) As the filling adhesive in the gap between the hole and the anchor, desirably, the main component of epoxy resin adhesive and the curing agent are used, and they are thoroughly stirred and mixed using a stirrer or a spatula outside the hole, and there is no poor mixing After confirming that, filling the polyolefin cartridge, using a caulking gun to inject a predetermined amount so that air does not mix in the back of the hole, and
(3) As a mushroom-type bottom expansion anchor, including an anchor having a bottom expandable portion at the tip portion, and a step of expanding the bottom expandable portion by driving the anchor body after being inserted into the hole,
After the epoxy resin adhesive is cured, the entire hole centered on the anchor that spreads in the shape of an anchor is easily removed by integrating the mushroom-shaped resin cured product and the anchor together and strongly adhering to the hole wall. This is a construction method using a mushroom-type post-construction anchor that can obtain a mushroom-type anchor without any other. If a deformed bar or round bar without an expanded bottom is used as an anchor, the pulling strength is low, but it is effective depending on demand. Also, as the filling adhesive, the pull-out strength is low and the curing time is slow, but instead of the epoxy resin adhesive, cement adhesives such as “Super Uni”, “Semen Power”, “Partner” manufactured by Unique Co., Ltd. Can be used.

  As described above, in the present invention, the post-construction anchor does not easily come off even when a load is applied vertically like the ceiling plate of the insulator tunnel. As will be described later, the pulling strength of mushroom-type widened anchors with embedded lengths of 10 cm and 15 cm with a widened part at the end of the D19 deformed reinforcing bar is 111 kN and 100 kN, respectively. It was cut off. Considering that it is decided that the short-term allowable pull-out force of suspended ceiling system post-installed anchors is 12 kN or more (see Ohm Co., “Post-installed anchors for building equipment”, P87 and 88), the mushroom-type widened anchor of the present invention For example, it can be seen how large the pulling force of D19 is 100 kN or more.

It is explanatory drawing of all the processes of this invention. It is explanatory drawing of an inside main process. It is explanatory drawing of an under cutter. It is explanatory drawing of an anchor-shaped widening anchor (back). It is explanatory drawing in the case of an anchor with a long bottom piece. It is explanatory drawing of an anchor-like widening anchor (to entrance). It is explanatory drawing of a spring system bottom expansion anchor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and is not limited to specific examples of the embodiments and examples described below.

  FIG. 1 is an explanatory diagram of a process of a construction method (hereinafter referred to as “the present method”) using a mushroom type post-construction anchor according to the present embodiment, and FIG. 2 is an explanatory diagram of an inner main process. The method consists of three steps. Each step will be described.

  First, a pilot hole 2 is drilled in a concrete structure using a hammer drill 1. The bottom is provided with an undercutter 3 at the back.

  A hammer drill with a two-hand handle is equipped with the undercutter shown in Fig. 3. Insert the undercutter 3 into the already drilled pilot hole 2 and gradually push it into the back with both hands. The under cutter consists of an outer cylinder 6 and an inner shaft 7, and when the outer cylinder 6 stops on the concrete surface, only the inner shaft enters the hole. In addition, the spring 8 gradually contracts at the same time. When the bottom 4 of the undercutter and the center needle 5 are in contact with the bottom of the hole, the support 10 of the cemented carbide tip 9 provided at the tip of the inner shaft 7 slides on the slope 11 and makes a face out of the window 12. Since the inner shaft 7 is connected to an electric motor and rotates, the carbide tip cuts the concrete wall at the bottom of the hole. As the handle is pushed in, the bottom cavity gradually expands. For example, when it is desired to widen the 10 mm hole, if the stopper 13 is provided so that the handle cannot be pushed further, the cutting allowance 14 of the bottom expanded portion can be adjusted to 10 mm. Taking into account the thickness of the cemented carbide tip, the strength of the pin 15, the diameter of the undercutter, the speed of cutting the widened portion, the electric power, etc., the cutting is performed without difficulty. If a scale 16 is provided on the side of the stopper 13, it is possible to know how many millimeters have been cut.

  After the bottom expansion process is completed, if the undercutter is removed from the hole, the spring 8 that has shrunk will return to its original position, and the carbide tip will be pulled out of the hole.

  In addition, the carbide bit is always pushed by the repulsive force of the spring, but when there is an obstacle such as a reinforcing bar in the widened part, the carbide bit does not slip and damage the blade due to the presence of the spring. Of course, it can be sharpened with a diamond bit as well as a carbide bit.

  By the way, in the conventional expandable metal anchor, the expanded portion of the anchor is expanded to the full width of the hole by core rod driving, main body driving, internal cone driving, sleeve driving, or torque wrench tightening (wedge type). On the other hand, the anchor of the present method expands the tip of the anchor and makes it a shape. If it is in the form of an anchor, it will not come off easily even if it is pulled. Although the conventional mechanism can be used for the expansion mechanism, the simplest and most economical anchor body driving type was selected. In this anchor, the deformed reinforcing bar 17 and the tip of a round bar were processed to provide an enlarged bottom portion 18 and a simple work of cutting a screw 19 on the head was followed by a rust-preventive plating finish. FIG. 4 shows an anchor-like post-installed anchor in which the expanded bottom piece extends in the depth direction of the hole, and FIG. 5 shows an anchor-like post-installed anchor that extends in the direction of the hole entrance.

  The bottom expanded anchor (backward) shown in FIG. 4 is composed of a deformed reinforcing bar 17 having a bottom expanded portion 18 and a tapered cone 20. When the anchor head driving portion 21 is hit with a hammer 2 to 3 times, the tapered cone 20 is formed. Therefore, the tapered portion 20-a enters the recessed portion 18-b of the widened portion, and the widened piece 18-a is pushed outward. Since this bottom expansion anchor has four cuts 18-c, the four bottom expansion pieces are pushed out and expanded to fill up the bottom expansion portion.

  The widened piece has a thickness of 2 to 3 mm and is easily bent outward by a thin bent portion bead 18-d. The depth of the recessed bottom 18-b and the length of the bottom expanded piece 18-a and the corresponding tapered cone 20 can be overlapped to lengthen the bottom expanded piece of the anchor-shaped expanded bottom anchor (see FIG. 5).

  Next, after injecting the epoxy resin adhesive as the filling adhesive, insert the bottom expansion anchor, drive the main body, and after confirming that the epoxy resin adhesive was filled in the gap with the bottom expansion piece fully expanded (eating The determination is based on the amount of protrusion), and a washer 25 is fitted on the screw 19 and a nut 26 is fitted and fixed. Adhesive is also attached to the back of the washer, and the part that partially protrudes outside the washer also contributes to adhesion.

  FIG. 6 is a diagram of an anchor-shaped widened anchor (toward the entrance). Compared with FIG. 4 described above, the positions of the bottom expanding piece 20-a and the tapered cone 20 are upside down. Therefore, there is a difference in how the bottom piece expands in the back direction or the entrance direction.

  FIG. 7 is a view of a spring-type widening anchor. A ring-shaped sleeve 22 is fitted into the tip of the deformed reinforcing bar 17, and the spring 23 is compressed and pushed into it. When the driving portion 21 is hit with a hammer, the deformed reinforcing bar 17 body pushes out the spring 23 in the sleeve 22. The spring extends freely and expands to the full expanded portion 24. This is also a kind of mushroom type bottom expansion anchor.

  The epoxy resin adhesive of this method is completely different from the conventional chemical anchor in both composition and mixing method. With conventional chemical anchors, neither a stirrer nor a spatula can be used in a narrow hole, so sufficient mixing is impossible. Moreover, as the viscosity of the adhesive increases, it becomes impossible to stir more and more, so an inexpensive filler cannot be added to the formulation.

  On the other hand, in this method, the main agent and the curing agent two liquids are thoroughly stirred and mixed using a stirrer or a spatula outside the hole, and the injection process can be started after confirming that there is no “mixing failure”. . The main agent and curing agent are colored in light red and light blue in advance, and when mixed, they become a complementary color and white. In addition, by adding a thixotropic agent, it is possible to have a characteristic that does not sag even when hitting with a caulking gun toward the ceiling. If necessary, the curing can be freely adjusted by adjusting the type and amount of the curing agent.

  The well-mixed adhesive prepared in this manner is packed in a polyolefin cartridge, mounted on an inexpensive caulking gun, and poured into the expanded bottom using a long nozzle. In addition, it is preferable to pay sufficient attention so that air does not enter during injection. After that, when the anchor-shaped widened anchor is inserted and the anchor main body driving portion is hit with a hammer two or three times, the bottom-expanded piece expands to fill the hole in a crisp shape.

  Thus, after the epoxy resin is cured, the expanded bottom portion, the anchor portion, and the entire hole portion are integrated into a mushroom shape by the resin and are firmly adhered to the hole wall surface, so that they cannot be pulled out easily.

  In this case, it is preferable that the amount of the adhesive fills the gap between the holes so that the excess part protrudes slightly from the hole entrance.

  Finally, the washer is fitted and the nut is tightened to fix it. The epoxy resin adhesive can be adjusted so that it completely cures in a few hours depending on the temperature.

In addition to the conventional capsule method, there is a mixing method in which two components of the main agent and curing agent are packed in separate cartridges and using a device with a static mixer at the end. Sufficient mixing is obtained, but the main agent and curing agent are once added. Mixing devices are disposable and expensive because they mix when mixed.
On the other hand, in this method, after mixing the main agent and curing agent, they are packed in a polyolefin cartridge, attached to an inexpensive caulking gun, and the adhesive is injected. Since it does not stick to the inner surface, it can be removed and regenerated.

  In addition, although this method is performed with respect to a concrete structure, as long as the same effect can be acquired, it will not be limited as a structure, For example, it can perform also with respect to the structure of wood.

  The effect of the mushroom type post-installed anchor according to the above embodiment was confirmed by performing a pull-out test using Protester T1-20 (measurement range 0 to 200 kN) manufactured by Trust, an anchor pull-out tester.

  A hole having a diameter of 22 mmΦ and a depth of 160 mm was drilled with a hand drill, and was sharpened and expanded with a cemented carbide tip 9 of an undercutter 3 (designed to have an outer diameter of 20 mmΦ so as to enter the hole). The maximum inner diameter of the hole in the widened portion was 40 mmΦ.

  As the epoxy resin adhesive, “ROAD EPO” manufactured by Unique Co., Ltd. was used. The main agent (epoxy resin) and the curing agent were mixed in an amount of 1: 1 and mixed thoroughly with a spatula. The viscosity is about 50,000 mPa · s / 23 ° C. and thixotropy. The main agent and the curing agent are colored light red and light blue, respectively, and when two liquids are mixed, they become white due to a complementary color relationship. The product was packed in a commercially available 330c polyolefin cartridge, attached to a caulking gun, and a predetermined amount was injected into the expanded bottom portion of the hole using a long nozzle.

  Next, after inserting the anchor-shaped widened anchor (backward) shown in FIG. 4 into the hole, the anchor head driving portion 21 is strongly struck three times with a hammer to form the four widened pieces 18-a outwardly. I expanded it to a hole. The adhesive filled the gap between the hole wall and the anchor, and the excess protruded from the entrance. The work was completed by tightening and fixing the anchor nut. The adhesive hardens at about 23 hours / 23 hours depending on the temperature.

  When each of these was evaluated, the mushroom-type widened anchor was provided with a widened portion at the tip of the deformed reinforcing bar D19, and the three types of pull-out forces with embedded lengths of 5 cm, 10 cm, and 15 cm were 65 kN and 111 kN, respectively. In the case of 100 kN, especially 10 cm, the thread of the coupler for anchor connection of the measuring machine was broken. In the case of 15 cm, the D19 rebar was cut.

  As a result, the effects of the present invention could be confirmed.

  INDUSTRIAL APPLICABILITY The present invention has industrial applicability as a mushroom-type bottom expansion post-construction anchor and construction method.

DESCRIPTION OF SYMBOLS 1 ... Hammer drill 2 ... Pilot hole 3 ... Under cutter 4 ... Bottom 5 ... Center needle 6 ... Outer cylinder 7 ... Inner shaft 8 ... Spring 9 ... Carbide tip 10 ... Support 11 ... Slope 12 ... Window 13 ... Stopper 14 ... Cutting allowance 15 ... Pin 16 ... Scale 17 ... Deformed bar
18 ... bottom-expanded part 18-a ... bottom-expanded piece 18-b ... recessed part 18-c ... notch 18-d ... bead 19 ... screw 20 ... tapered cone 20-a ... Taper 21 ... Driving part 22 ... Sleeve 23 ... Bottom expansion spring 24 ... Bottom expansion part 25 ... Washer 26 ... Nut

Claims (3)

After drilling a hole with a drill, the process of providing an expanded bottom portion using an undercutter at the bottom of the hole;
Injecting the filling adhesive in the gap between the hole and the anchor into the back of the hole;
After inserting the anchor into the hole, the anchor body is driven and the bottom expanded portion is expanded in a crisp shape. The entire hole including the anchor expanded in the cradle shape is like a mushroom-shaped filling adhesive and the anchor. A construction method using a mushroom-type post-installed anchor that can be obtained by unifying and firmly adhering to the wall of the hole, so that it can be easily removed.   The step of injecting the filling adhesive in the gap between the hole and the anchor into the back of the hole uses the main component and the curing agent of the epoxy resin adhesive, and sufficiently stirs and mixes them using the stirrer or the spatula outside the hole. The construction method using the mushroom type post-construction anchor according to claim 1, wherein the construction method is a step of filling a cartridge and injecting a predetermined amount using a caulking gun so that air does not enter the back of the hole. The construction method using a mushroom-type post-installed anchor according to claim 1, wherein the step of driving the anchor after inserting the anchor into the hole is a step of driving an anchor having a bottom-expandable portion at the tip as a mushroom-type widened anchor.