JP2016079720A - Hole-in anchor and construction method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole-in anchor capable of securing its anchorage force even when a load acts over a long period of time or an aged deterioration in filler occurs, after construction.SOLUTION: An anchor bar 10, which has an anchorage part 11 obtained by shaping a bulge part formed by pressure-welding a tip of a reinforcing bar, is erected in an anchor hole in which peripheral surface grooves 5 are formed at predetermined groove intervals p, in a depth direction of an anchor hole wall 4 of existing concrete 1. The anchor bar 10 is held in the hole by filling the periphery of the anchor bar 10 with a filler 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a post-construction anchor and a construction method thereof, and the post-construction anchor and the post-construction anchor that can secure the fixing force even when a load is applied over a long period of time or the aging of the filling material occurs after construction. The present invention relates to a construction method for efficiently constructing a construction anchor.

  Conventionally, a post-construction anchor as shown in FIG. 5 (a) is known as a method of constructing a post-construction anchor on existing concrete with an adhesive anchor. In the construction of this type of post-construction anchor, an anchor hole 52 having a diameter slightly larger than the diameter of the anchor bar 50 is drilled in the existing concrete 51 using a drilling device such as a hammer drill, and encapsulated epoxy resin or cement. A filler 53, which is an adhesive material such as a grout, is inserted into the anchor hole 52, the anchor bar 50 is built into the hole by rotation and hammering, and the anchor bar 50 is fixed to the concrete frame 51 integrally. As shown in FIG. 5A, the tip 50a of the anchor muscle 50 is cut at an angle of 45 degrees on one side and finished sharply. As a result, the epoxy resin main agent and the curing agent in the capsule inserted in the anchor hole in advance are efficiently mixed, and the curing of the adhesive material is promoted.

  By the way, fillers such as epoxy resin and cement-type grout used as adhesive materials have high adhesion performance, but the epoxy resin and grout in the anchor hole shrinks when used over a long period of time, and the filler is smooth. There is a problem that a gap is generated between the anchor hole wall and the filler, and the adhesion performance is lowered.

  In order to solve this problem, by forming a plurality of grooves along the depth direction on the inner peripheral surface of the anchor hole wall and filling the filler into the grooves, the filler and the anchor hole wall A method of increasing the adhesion force between the anchor hole wall and the filler by mechanical locking is proposed (Non-Patent Document 1, FIG. 5B). According to this method, the filler 53 is formed in the groove 55. By filling the inside, the adhesion area between the anchor hole wall 54 is increased, so that a larger adhesion force is exhibited than in the case of the conventional smooth anchor hole wall 54. Further, even if a long period of time elapses after construction and the filler 53 contracts and a gap is formed between the anchor hole wall 54 and the filler 53, the gap between the filler 53 in the groove 55 and the anchor hole wall 54 is Since there is a mechanical locking, resistance to pulling out and the like is maintained.

  On the other hand, the transmission of stress between the anchor bar and the filler is performed by the adhesive force between the various irregular patterns formed on the surface of the deformed reinforcing bar used as the anchor bar and the filler. Since the rebar surface pattern is fine compared to the rebar diameter, the adhesion force per unit surface area is not so large. In order to give the rebar a predetermined fixing force (pullout strength), secure a predetermined fixing length and anchor It is necessary to embed in the hole.

  From the above, even when a plurality of grooves disclosed in Patent Document 1 are formed on the anchor hole wall, the adhesion strength between the reinforcing bar and the filler is equivalent to that of a conventional post-installed anchor, and the fixing length of the reinforcing bar The thickness is determined by the adhesion strength between the reinforcing bar and the filler. For this reason, in order to ensure the pullout strength of the anchor, the anchor length of the anchor muscle cannot be shortened. As a solution to this problem, a fixing plate is attached to the tip of an anchor bar (reinforcing bar) to increase the adhesion between the reinforcing bar and the filler and improve the pull-out strength.

  For example, as an anchor structure for attaching a fixing plate to the tip of a reinforcing bar, an anchor bolt used for attaching a steel member such as a steel column base is conventionally known. As this type of anchor bolt, an anchor structure is used in which a disk-shaped fixing plate is attached to the lower end of the bolt using a high-strength bolt or a male screw member and both fastening nuts (Patent Document 1). These anchor bolts are attached in advance to a base installed at a predetermined position in the formwork, and then concrete is cast thereon, and a column base plate is installed at the top position of the concrete.

JP 2008-3149 A

Tanaka Dia Kogyo Co., Ltd., “Pulling test of anchor bolts placed in holes with grooves”, [online], June 28, 2013, Tanaka Dia Kogyo Co., Ltd. website, July 1, 2014 Search, Internet <URL: http://www.tanakadaiya.com/license/>

  Conventionally, in the design of post-installed anchors, there has been no example considering the change of the filler over a long period of time, and there has been no method of eliminating the lack of adhesion between the anchor bar and the filler using a fixing plate. Furthermore, in the construction work, an anchor bar to which a fixing plate is attached cannot be used for an anchor hole drilled by a post-construction anchor construction method. In addition, when constructing a large number of anchor bars, if the work of the material for attaching the fixing plate to the tip of the anchor bars can be simplified, the construction period will be shortened. Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to fix anchor muscles that are subjected to stress or repetitive stress for a long period of time with a shorter fixing length than conventional post-installed anchors to the housing side. Another object of the present invention is to provide an anchor that can be made and an anchor construction method that can save labor compared to conventional construction.

  In order to achieve the above object, the post-construction anchor according to the present invention has an anchor bar having a fixing portion at the tip end in an anchor hole in which a circumferential groove is formed in the hole wall at a predetermined groove interval in the depth direction. The periphery of the anchor muscle is filled with a filler, and the anchor muscle is held in the hole.

  It is preferable that the fixing portion is formed by shaping a bulge portion formed by pressure-welding the tip of an anchor bar.

  The fixing portion is preferably a steel fixing plate attached to the tip of an anchor bar.

  It is preferable to provide the fixing portion also at an intermediate position in the length direction of the anchor muscle.

  It is preferable that a groove interval in a range from the fixing unit upper surface position to a position intersecting with the hole wall at an angle of θ = 45 to 60 ° is smaller than outside the range.

  As an invention of post-construction anchor construction method, circumferential grooves are formed at predetermined intervals in the depth direction in the hole wall of the anchor hole, anchor bars having a tip anchoring portion are built, and the periphery of the anchor bars is filled with a filler. Filling and holding the anchor muscle in the hole.

  It is preferable that the anchor line is built up while standing at the bottom of the hole via the fixing portion, and the fixing portion is installed at the bottom of the hole with the assistance of an anchor support member.

  As described above, according to the present invention, there is provided an anchor that can reliably fix anchor muscles that are subjected to stress or repeated stress for a long period of time, with a shorter fixing length than conventional post-installed anchors. It is also possible to save labor compared to conventional construction.

Explanatory drawing which showed the construction state of embodiment (fixing part shape) of the post-construction anchor of this invention. Explanatory drawing which showed other embodiment (groove space | interval change) of the post-construction anchor of this invention. Explanatory drawing which showed the example of the fixing part formation method of the post-construction anchor of this invention. Explanatory drawing which showed the work procedure of the construction method of the post-construction anchor of this invention. Explanatory drawing which showed the example of the form of the conventional post-construction anchor.

Hereinafter, embodiments of a post-construction anchor and a construction method thereof according to the present invention will be described with reference to the accompanying drawings. FIG. 1 (a) shows a state in which a construction anchor is installed on an existing concrete frame 1 after the present invention.
The anchor bar 10 shown in FIG. 1A has a fixing portion 11 at the lower end. As will be described later, the fixing portion 11 is formed by shaping a bulging portion formed by deforming an end portion of a reinforcing bar. Further, the end surface of the fixing unit 11 is constituted by a smooth cut surface. On the other hand, since the bottom surface 3 of the anchor hole 2 does not become a smooth surface when the drilling is completed, when the anchor bar 10 having the diameter d is erected on the bottom surface 3 of the anchor hole 2, as shown in FIG. It is preferable that the anchor reinforcement is erected so as to stand up through the filling and solidifying material as the support material 12. As the anchor support material 12, an epoxy resin putty, various resin adhesives, a filling solidified material such as quick setting mortar, or a metal or resin that can secure a predetermined height with respect to the bottom surface 3 as a mechanical support material. A spacer made of the like can be used. The outer shape of the fixing unit 11 is chamfered so as to have a circular cross section having a predetermined diameter (D1). When the anchor muscle 10 having the fixing portion 11 is accommodated in the anchor hole, the anchor hole is provided so that a gap having the following relationship is provided between the fixing portion 11 and the surrounding anchor hole wall 4. The diameter (Dh) is set.

The relationship between the thickness (diameter: d) of the anchor muscle 10 and the diameter (D1) of the fixing portion 11 is as follows:
D1 = (1.5 to 2.5) × d
The relationship between the diameter (D1) of the fixing portion 11 and the diameter (Dh) of the anchor hole is
Dh = D1 + Δ
At this time, as shown in FIG. 1A, the gap Δ can be made small as long as the fixing portion 11 of the anchor bar 10 can be installed on the bottom surface 3 of the anchor hole.

  Furthermore, a ring-shaped peripheral groove 5 that is horizontal to the anchor hole wall 4 is formed in the anchor hole wall 4 along the depth direction. The peripheral groove 5 can be formed in the anchor hole wall 4 by the apparatus described in Non-Patent Document 1 described above or other known groove forming apparatus. When the peripheral groove 5 is a square groove as shown in the figure, the groove dimensions are groove depth Gd: about 2 to 5 mm, groove width Gw: about 9 to 20 mm, anchor depth direction interval p: about 50 to 100 mm. Can be set to It is preferable that the specific groove dimensions are appropriately designed and set according to the required fixing force of the anchor muscle 10. For example, the ratio of the depth and height of the square groove at the time of design is preferably 1: 4 to 5 in order to maintain the adhesive force. Further, the groove cross-sectional shape can be a shape that allows easy cutting of the surface of the hole wall 4 if the groove width that affects the shear strength of the filler 13 is secured, for example, a substantially circular groove or a triangular groove. You can also.

  FIG. 1B shows an installation state of the post-construction anchor using the anchor bar 10 having the modified fixing portion 11 attached to the tip. The fixing unit 11 is a steel disk having a predetermined diameter (D2) fixed to the tip of the anchor bar 10 by screwing. For screwing, it is preferable to flatten the bottom surface of the fixing unit 11 using a countersunk screw 15. When a male screw is formed as the deformed pattern of the anchor muscle 10, a ring-shaped disk in which a female screw that can be screwed to the male screw of the anchor muscle 10 can be used. In addition, a commercially available fixing plate for reinforcing bars can also be used.

  FIG. 2A is an explanatory view showing a hole wall cross section of the embodiment of the construction anchor after changing the groove pitch formed in the hole wall 4 in consideration of the bearing pressure effect in the fixing portion 11. When a pulling force acts on the anchor muscle 10, the fixing portion 11 exerts a large supporting pressure on the filler 13. It is preferable to increase the adhesive force over a predetermined range (range (a)) between the filler 13 and the anchor hole wall 4 to such an extent that the entire anchor can exhibit the strength (proof strength) corresponding to the support pressure. The range (a) is set on the assumption that the support pressure of the fixing unit 11 reaches when the pulling force acts on the anchor muscle 10. Specifically, as shown in FIG. 2, the interval between the circumferential grooves 5 located within a range that forms an angle θ (θ = 45 to 60 °) from the center position of the upper surface of the fixing unit 11 is made dense. As a balance of the entire groove interval, the groove interval in the range (a) is preferably set to an interval p1 (p> p1) narrower than the groove interval p shown in FIG. In this case, a sufficient anchor fixing effect can be obtained in the range (a) from the fixing unit 11, and therefore, in the range (b) from the fixing range (a) to the anchor mouth, the interval p2 can be set to p2> p.

  FIG. 2B is an explanatory view showing a hole wall cross section of an embodiment of a post-installed anchor using an anchor bar 10 provided with an intermediate fixing portion 14 in addition to the fixing portion 11 at the tip of the anchor. In the case of a post-installed anchor that is designed to have a large anchor attachment length, an intermediate fixing portion 14 can be provided in addition to the tip fixing portion 11. After that, in the construction anchor, in addition to designing the groove interval to be narrow (groove interval: p1) from the tip fixing portion 11 in the range (a), the groove is also in the range (a) from the intermediate fixing portion 14 position toward the anchor mouth. The interval can be set narrow (groove interval: p1), and the other range (b) can be set as the groove interval p2.

  FIG. 3 is an explanatory view showing a procedure in which a bulging portion 7 b is formed on the end surface 7 a at the tip of the reinforcing bar 7, and the bulging portion 7 b is shaped to form the anchor bar 10 having the fixing portion 11. The manufacturing procedure of the anchor muscle 10 will be briefly described with reference to the drawings. Two rebars 7 (deformed bar steel) to be the anchor bars 10 are held by a clamp (not shown) so as to be in a coaxial straight line (FIG. 3A). At this time, a release agent is applied to the end surface 7a with which the reinforcing bar comes into contact. Thereafter, when the end of the abutted reinforcing bar 7 is pressurized and pressed until it is heated to a red-hot state, as shown in FIG. A bulging portion 7b is formed. Thereafter, the two bulging portions 7b in the pressure contact state are integrally shaped by a rotary cutting device (not shown) (FIG. 3C), and a fixing portion 11 having a predetermined shape is formed at the end of the reinforcing bar 7. . By separating the two anchor bars 10 at the peeling surface 7c, two anchor bars 10 having a substantially truncated cone-shaped fixing portion 11 having the same shape at each end can be obtained (FIG. 3D). )).

  FIG. 4 is an explanatory view showing a construction procedure of a post-construction anchor according to the present invention. Unlike conventional post-installed anchors, post-installed anchors according to the present invention are constructed in such a way that anchor bars are pre-installed and stably held in the anchor holes, and then the filler bars are filled and solidified to fix the anchor bars. It is characterized by being fixed inside. First, as shown in FIG. 4A, a predetermined position of the existing concrete 1 is drilled, and the anchor hole 2 is provided with a diameter slightly larger than the diameter of the fixing portion 11 of the anchor bar 10 to be built. Next, a plurality of grooves 5 are formed on the inner peripheral surface of the hole by an in-hole groove drilling device. The dimension of the groove 5 and the interval in the depth direction are designed within the range shown in FIG. 1A described above according to the standard of the anchor bar 10 to be used. When the formation of the peripheral groove 5 is finished, the concrete pieces and scraps accumulated on the bottom surface 3 are removed with compressed air, water, etc., and cleaned again. In the present embodiment, a ring-shaped steel spacer 16 is installed on the bottom surface 3 of the anchor hole 2 as an aspect of an anchor support material for erecting the fixing portion 11, and the anchor bar 10 is erected thereon. (FIG. 4B). As a result, the anchor bar 10 inserted into the anchor hole 2 is self-supporting when the anchor fixing portion 11 is placed on the steel spacer 16 installed on the bottom surface 3. Furthermore, it is also preferable to attach a spacer 17 to the mouth of the anchor hole 2 in order to erect the anchor muscle 10 at the center position of the cross section of the anchor hole (FIG. 4C). Thereafter, the cement grout material as the filler 13 is filled around the anchor muscle 10 of the anchor hole 2. In order to fill the grout material, a grout material filling hose is inserted into the anchor hole, and the grout material is filled into the anchor hole 2 while the hose is pulled out. The filler 13 may be a chemical material mainly composed of an epoxy acrylate resin or an epoxy resin in addition to the cement material. By setting a predetermined curing period, it can be used as a post-construction anchor having a predetermined pulling strength.

  In addition, this invention is not limited to the Example mentioned above, A various change within the range shown to each claim is possible. In other words, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Existing concrete 2 Anchor hole 4 Anchor hole wall 5 Circumferential groove 10 Anchor reinforcement 11 Fixing part (tip fixing part)
12 Anchor support material 13 Filler material 14 Intermediate fixing portion

Claims (8)

  An anchor bar having a fixing portion at the tip is built in an anchor hole having a circumferential groove formed in the hole wall at a predetermined groove interval in the depth direction, and the anchor bar is filled with a filler material around the anchor bar to fill the anchor bar in the hole. Post-construction anchor characterized by holding.   The post-construction anchor according to claim 1, wherein the fixing portion is formed by shaping a bulge portion formed by pressure-welding the tip of an anchor bar.   The post-construction anchor according to claim 1, wherein the fixing portion is a steel fixing plate attached to a tip end of an anchor bar.   The post-construction anchor according to claim 1, wherein the fixing portion is also provided at an intermediate position in the length direction of the anchor bar.   2. The post-construction according to claim 1, wherein a groove interval in a range from the upper surface position of the fixing unit to a position intersecting with the hole wall at an angle of θ = 45 to 60 ° is made smaller than outside the range. anchor.   Peripheral grooves are formed in the hole wall of the anchor hole at a predetermined interval in the depth direction, an anchor line having a tip fixing portion is built, the area around the anchor line is filled with a filler, and the anchor line is held in the hole. An after-construction anchor construction method characterized by this.   The post-construction anchor construction method according to claim 6, wherein the anchor bars are built up while standing at the bottom of the hole via the fixing portion.   The post-construction anchor construction method according to claim 7, wherein the fixing portion is installed at the bottom of the hole with the assistance of an anchor support material.

Images