Patent Description:
Conventionally, a known adhesive anchor is of a type including a chemical anchor rod having an indicator to indicate an embedding depth in its rod body and adhesive filled in the gap between the rod body and the inner wall of an embedding hole (see Patent Document <NUM>).

The chemical anchor rod includes the rod body of a full thread inserted into the embedding hole bored in a base material, and the head part of an exposed portion of the rod body is provided with a fastening end having a polygonal shape in a plan view, the maximum length of the fastening end being the same as the length of the diameter of the rod body at most. Further, the indicator to indicate an embedding depth is cut into the barrel part of the rod body over the outer periphery of the rod body. By adapting a hammer drill or the like to the fastening end, it becomes possible to easily embed the rod body in the embedding hole and embed the rod body in the embedding hole at a proper embedding depth with the indicator as a guideline.

As a post-installed anchor, a conventional adhesive anchor (chemical anchor rod) as described above has an embedding depth <NUM> times or more (<NUM> times is recommended) of an anchor diameter, while a metal expansion anchor (mechanical anchor) has an embedding depth (effective embedding length) four to five times (seven times in the case of ensuring reliability) of an anchor body diameter (for example, P53 to P67 of the document "<NPL>).

It is described in the document that cone failure is caused in concrete in a state in which substantial tensile strength is not obtained when an adhesive anchor has an embedding depth (effective embedding length) about five times of an anchor diameter, that mushroom-shaped superposed failure is caused in concrete at a shallow position and bond failure is caused between adhesive and concrete at a deep position in a state in which substantial tensile strength is not obtained when the adhesive anchor has an embedding depth about seven to eight times of the anchor diameter, and that the adhesive anchor preferably has an embedding depth <NUM> times or more of the anchor diameter to obtain substantial tensile strength (however, mushroom-shaped superposed failure is also caused in this case). Note that the effective embedding length (le) = the boring depth (<NUM>) of concrete - the diameter (de) of an anchor bolt is established. The phenomena peculiar to the adhesive anchor (particularly, the mushroom-shaped superposed failure) have also been confirmed in pulling examination by the Applicant.

As described above, there has been a problem that the conventional adhesive anchor has a deeper embedding depth and poorer construction performance in comparison with the metal expansion anchor (mechanical anchor). Another anchor bolt is known from <CIT>.

The present invention has an object of providing an anchor bolt for an adhesive anchor, an adhesive anchor, and a method for constructing an adhesive anchor that can be caused to exert substantial tensile strength at a relatively shallow embedding depth.

An anchor bolt for an adhesive anchor according to claim <NUM> of the present invention is an anchor bolt for an adhesive anchor that is fixed via adhesive to an anchor hole formed in a fixed body, the anchor bolt including: a head part that is inserted into a hole back part of the anchor hole; a shank part that is continuous with the head part and formed to have a diameter smaller than a diameter of the head part; and a sleeve part into which the shank part is inserted, the sleeve part extending from an opening part to the hole back part of the anchor hole and having a tip end thereof abutted onto the head part, wherein an outer peripheral surface of the sleeve part is secured by the adhesive to contribute to tensile strength.

According to the configuration, a tensile force (pulling force) acts on the sleeve part as a compressive force via the head part when the tensile force acts on the shank part in a state in which the anchor bolt is fixed to the anchor hole via the adhesive. Since the sleeve part is secured by the adhesive filled between the sleeve part and the anchor hole in this case, the anchor bolt exerts a wedge effect on the fixed body at the head part. Further, since the tensile force (compressive force) acts on the sleeve part from the tip end side via the head part, the tensile force does not intensively act on the base end side (on the side of the opening part) of the sleeve part and failure (mushroom-shaped superposed failure) is not caused at a shallow portion of the fixed body. Accordingly, substantial tensile strength can be exerted at a shallower embedding depth over conventional art. Further, since the shank part does not directly contact the adhesive, the toughness of the anchor bolt (shank part) useful for supporting a structure is not impaired.

Note that the head part and the shank part may be integrated with each other or may be separated from each other (by screw connection or the like). Further, the fixed body includes, besides concrete, stone or the like for which an adhesive anchor is generally used. Needless to say, the tip end of the head part is preferably formed into a shape cut at <NUM>° or the like when adhesive of a capsule type is used.

In this case, the tip end of the sleeve part is preferably anchored to the head part.

According to the configuration, the sleeve part and the head part are integrated with each other. Therefore, the sleeve part is not deviated or displaced from the head part in construction or the like, whereby operability or construction performance can be improved.

Note that the sleeve part is anchored to the head part by welding, adhesion or screw connection.

In these cases, the outer peripheral surface of the sleeve part that contacts the adhesive is preferably formed into an irregularity shape.

According to the configuration, the shearing resistance (pulling resistance) of the adhesive filled between the sleeve part and the anchor hole can be substantially exerted.

Further, the anchor hole preferably has a straight hole part that extends from the opening part to the hole back part, and the head part preferably has a circulation part that causes the adhesive to relatively circulate from a tip end side to a base end side thereof during the insertion.

According to the configuration, the adhesive relatively flows inside the circulation part when the anchor bolt is inserted into the anchor hole, whereby the viscous resistance of the adhesive can be reduced. Thus, the insertion of the anchor bolt into the anchor hole can be smoothly performed. Further, in the case of adhesive of a capsule type, the stirring of the adhesive can be accelerated by the circulation unit.

Note that the circulation unit is preferably a groove formed on the outer peripheral surface of the head part or a hole penetrating the head part. That is, the circulation part is preferably an inclined groove or an inclined hole inclined with respect to an axial line, besides being a vertical groove or a vertical hole parallel to the axial line. Further, the circulation part may be singly provided, but a plurality of the circulation parts are more preferably provided in a.

Similarly, the anchor hole preferably has a diameter expanded part at the hole back part into which the head part is inserted, the diameter expanded part preferably has a tapered hole part that expands toward a hole bottom side, and the head part preferably has a tapered surface part that faces the tapered hole part.

According to the configuration, the tensile force (pulling force) that is applied to the head part can be caused to act not only on the adhesive but also on the fixed body via the tapered hole part by the tapered surface part in a dispersed manner. As a result, tensile strength can be improved as a whole.

An adhesive anchor according to the present invention includes: the anchor bolt for an adhesive anchor described above; and the adhesive filled in a gap between the anchor hole and the anchor bolt.

According to the configuration, substantial tensile strength can be exerted at a shallower embedding depth over conventional art in the anchor bolt secured to the anchor hole via the adhesive.

A method for constructing an adhesive anchor of the present invention is a method for constructing the adhesive anchor described above, the method including: a boring and cleaning step of boring the anchor hole in the fixed body and cleaning an inside of the anchor hole; an injection step of injecting the adhesive into the anchor hole; an insertion step of inserting the anchor bolt into the anchor hole; and a setting step of maintaining a position of the anchor bolt inside the anchor hole until the adhesive is cured.

According to the configuration, the anchor bolt exerts a wedge effect with respect to a tensile force when the adhesive is cured after the setting step. Accordingly, the adhesive anchor that exerts substantial tensile strength at a shallower embedding depth over conventional art can be configured.

Hereinafter, an adhesive anchor according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the adhesive anchor, adhesive is sunk into the hole wall of an anchor hole bored in concrete (fixed body), and an anchor bolt is secured to the concrete with the shearing resistance of the cured adhesive. Particularly, in the adhesive anchor of the present embodiment, a tensile force is intensively applied to the tip end side of an anchor bolt to cause concrete to exert proper bearing strength. Note that the term "anchor bolt" will be hereinafter used as the generic name of a member (that is not limited to a bolt) embedded in concrete to support a structure in an adhesive anchor.

<FIG> is a structural view of an adhesive anchor according to a first embodiment. As shown in the figure, an adhesive anchor 10A includes an anchor bolt 11A (anchor bolt for an adhesive anchor) that is inserted into an anchor hole AH formed in concrete C (fixed body) and adhesive <NUM> that is filled in the gap between the anchor hole AH and the anchor bolt 11A. The anchor bolt 11A is formed of steel, stainless steel, or the like and integrally formed by a head part <NUM> that is inserted into the hole back part of the anchor hole AH and a shank part <NUM> that is continuous with the head part <NUM>. Further, the shank part <NUM> is provided with a sleeve part <NUM> that is inserted so as to make its tip end part abutted onto the head part <NUM>.

The head part <NUM> is formed into a substantially columnar shape and has a guide surface 21a that guides insertion into the anchor hole AH on its tip end side. The head part <NUM> has a flat surface that is orthogonal to an axial line on its base end side, and the sleeve part <NUM> is abutted onto this portion. That is, in an axial direction, the head part <NUM> is integrally formed by a column-shaped part <NUM> that constitutes a main body and a guide surface part <NUM> on the tip end side that has the guide surface 21a.

The anchor hole AH is formed into a straight shape from an opening part Ha to a hole bottom Hb, and the diameter (outer diameter) of the head part <NUM> is formed to be smaller by <NUM> to <NUM> than that of the anchor hole AH (straight hole part). Since the anchor hole AH is bored by a vibration drill or a hammer drill in this case, the diameter of the anchor hole AH corresponds to the bit diameter of such a drill. It cannot be expected that the bored anchor hole AH has high-accurate circularity or linearity due to the characteristics of a used drill. Accordingly, a measure of the "<NUM> to <NUM>" is a value at which the insertion of the anchor bolt 11A is made possible when the anchor bolt 11A is lightly implanted into the anchor hole AH or a value at which the insertion of the anchor bolt 11A is made possible when the anchor bolt 11A is strongly pressed into the anchor hole AH.

The shank part <NUM> is formed to have a diameter substantially smaller than that of the head part <NUM>. The shank part <NUM> is integrally formed into a rod shape by an embedded part <NUM> that is continuous with the head part <NUM> and embedded in the anchor hole AH and a support screw part <NUM> that is continuous with the embedded part <NUM> and protrudes to the outside of the anchor hole AH. The support screw part <NUM> is a portion that supports an object and has a male screw on its outer peripheral surface. An object (structure) that is supported by the support screw part <NUM> is bolted by the support screw part <NUM> (not shown). Note that the diameter (nominal diameter) of the anchor bolt 11A is the diameter of the shank part <NUM>.

The embedded part <NUM> is formed into a round-bar shape having no irregularities on its outer peripheral surface. The head part <NUM> and the shank part <NUM> are integrally formed with each other in the present embodiment but are preferably formed into a shape obtained by cutting a round bar, a shape obtained by subjecting a round bar to rolling, a shape obtained by welding the head part <NUM> to the shank part <NUM>, or the like.

However, in an example which is out of the scope of the claims, the head part <NUM> and the shank part <NUM> may be separated from each other. In such a case, it is preferable to employ a mode in which a male screw is formed at the tip end of the shank part <NUM> and a female screw is formed at the head part <NUM> and in which the head part <NUM> is screw-connected to the shank part <NUM>. Further, in a case in which the adhesive <NUM> is of a capsule type (that will be described later), it is preferable to perform processing such as obliquely cutting the tip end of the head part <NUM> at <NUM>°.

The adhesive <NUM> is constituted by epoxy adhesive having strong adhesion to the anchor bolt 11A and the concrete C. In this case, a two-part type is used as the adhesive <NUM> (epoxy adhesive). Further, as the adhesive <NUM> of a two-part type, there are a capsule type in which two liquids are encapsulated and then crushed inside the anchor hole AH to be stirred and mixed together and an injection type in which two liquids are stirred and mixed together in advance and then injected into the anchor hole AH (the details of which will be described later).

Note that besides epoxy adhesive, the adhesive <NUM> may be organic adhesive such as polyester adhesive and epoxy acrylate adhesive or may be cement inorganic adhesive. Particularly, since recent inorganic adhesive has higher strength than the concrete C and is highly resistant to degradation, the inorganic adhesive is useful as the adhesive <NUM> of the adhesive anchor 10A.

The sleeve part <NUM> extends so as to be adapted to the embedded part <NUM> of the shank part <NUM>. That is, the sleeve part <NUM> extends from the opening part Ha to the hole back part of the anchor hole AH. Like the shank part <NUM> or the like, the sleeve part <NUM> is formed of steel, stainless steel, or the like. In this case, the sleeve part <NUM> is formed so as to expose from the opening part Ha of the anchor hole AH by about several millimeters in consideration of the depth accuracy of the anchor hole AH.

The inner peripheral surface of the sleeve part <NUM> is formed to have almost the same diameter as that of the shank part <NUM> so that the shank part <NUM> is inserted into the sleeve part <NUM>. Further, the inner peripheral surface of the sleeve part <NUM> and the outer peripheral surface of the shank part <NUM> (the embedded part <NUM>) are formed by smooth surfaces having no irregularities. The inner peripheral surface of the sleeve part <NUM> and the outer peripheral surface of the shank part <NUM> (the embedded part <NUM>) are not adhered or secured to each other, and the shank part <NUM> is allowed to extend by a tensile force. On the other hand, the sleeve part <NUM> is anchored to the head part <NUM> by welding, adhesion, or screw connection.

Here, methods for constructing the adhesive anchor 10A will be described with reference to <FIG> and <FIG>. As described above, the adhesive <NUM> of the adhesive anchor 10A includes a capsule type and an injection type. <FIG> is an explanatory view of a case in which the adhesive of an injection type is used, and <FIG> is an explanatory view of a case in which the adhesive <NUM> of a capsule type is used. Each of these construction methods includes: a boring and cleaning step of boring the anchor hole AH in the concrete C and cleaning the inside of the anchor hole AH; an injection step of injecting the adhesive <NUM> into the anchor hole AH; an insertion step of inserting the anchor bolt 11A into the anchor hole AH; and a setting step of maintaining the position of the anchor bolt 11A inside the anchor hole AH until the adhesive <NUM> is cured.

The details of the boring and cleaning step are the same regardless of whether the capsule type or the injection type is used. In the boring of the anchor hole AH, a hole having a prescribed diameter and a prescribed depth is bored in the concrete C by a vibration drill or a hammer drill. In this case, the anchor hole AH is set to have a boring diameter greater by about <NUM> to <NUM> than that of the sleeve part <NUM> of the anchor bolt 11A having a small diameter, and is set to have a boring diameter greater by about <NUM> than that of the sleeve part <NUM> of the anchor bolt 11A having a large diameter. In the cleaning of the inside of the anchor hole AH, concrete powder (swarf) is sucked and removed by, for example, air suction or the like, and then the hole wall Hc is brushed to carefully remove the concrete powder inside the hole. The cleaning step is actually performed in the order of suction, brushing, and suction.

In the injection step of injecting the adhesive <NUM> of an injection type shown in <FIG>, two liquids constituting the adhesive <NUM> that had been stirred and mixed together in advance are injected into the anchor hole AH by an injector or the like. In this case, the amount of the injected adhesive <NUM> is preferably set at almost (an amount slightly larger than) an amount obtained by subtracting the volume of a portion in which the anchor bolt 11A is embedded from the capacity of the anchor hole AH.

After the injection of the adhesive <NUM> into the anchor hole AH, the anchor bolt 11A is inserted into the anchor hole AH so as to make the head part <NUM> reach the hole bottom Hb (insertion step). Specifically, the anchor bolt 11A is inserted into the anchor hole AH with the tip end of the sleeve part <NUM> abutted onto and anchored to the head part <NUM>. Then, after the insertion of the anchor bolt 11A into the anchor hole AH, an excess of the adhesive <NUM> is wiped off, and the anchor bolt 11A is set so as not to move until the adhesive <NUM> is cured (setting step).

On the other hand, in the injection step of injecting the adhesive <NUM> of a capsule type shown in <FIG>, a capsule K (actually expressed by the gram) adapted to the diameter and the boring depth of the anchor hole AH is prepared and put in the anchor hole AH. Before or after the putting of the capsule K, a coupler is attached to the support screw part <NUM> of the anchor bolt 11A, and the anchor bolt 11A is set in a drill (for example, a vibration drill) via the coupler.

Here, the anchor bolt 11A is inserted into the anchor hole AH in a state of being set in the drill, and rotated to crush the capsule K and stir and mix the two liquids together. Then, using the base end of the sleeve part <NUM> as a measure of an embedding depth, the anchor bolt 11A is embedded while the adhesive <NUM> is stirred and mixed together (insertion step). After the embedding of the anchor bolt 11A in the manner described above, the drill is removed. Then, the anchor bolt 11A is set so as not to move until the adhesive <NUM> is cured (setting step).

Next, a modified example of the anchor bolt 11A of which the mode of the head part <NUM> is different from that of the first embodiment will be described with reference to <FIG>. The head part <NUM> of the modified example has, on its outer peripheral surface, a plurality of circulation grooves <NUM> (circulation parts) that cause the adhesive <NUM> to circulate during its insertion into the anchor hole AH.

As described above, the diameter of the head part <NUM> is formed to be smaller by <NUM> to <NUM> than that of the anchor hole AH. As a result, the viscous resistance of the adhesive <NUM> strongly acts on the head part <NUM> when the anchor bolt 11A is inserted into the anchor hole AH. In order to address this, the outer peripheral surface of the head part <NUM> is provided with the plurality of (six in the embodiment) circulation grooves <NUM> in the modified example. The respective circulation grooves <NUM> are constituted by so called vertical grooves that extend parallel to each other in an axial direction and have a semicircular shape in cross section. Further, the six circulation grooves <NUM> are arranged at even intervals in a circumferential direction. Note that the cross-sectional shape of the circulation grooves <NUM> may be a rectangle, a trapezoid, or the like.

Since the head part <NUM> has the plurality of circulation grooves <NUM> as described above, the anchor bolt 11A can be smoothly inserted into the anchor hole AH even if the gap between the anchor hole AH and the head part <NUM> is small. Further, in a case in which the adhesive <NUM> of a capsule type is used, the stirring and mixture of the adhesive <NUM> can be accelerated by the circulation grooves <NUM>.

Note that although the six circulation grooves <NUM> are provided in the modified example, one or more pieces of the circulation grooves <NUM> is only required to be provided. Further, the circulation grooves <NUM> may be inclined grooves that are inclined with respect to the axial direction (to accelerate the stirring and mixture of the adhesive <NUM>). However, it is also possible to replace the circulation grooves <NUM> with circulation holes. Needless to say, the head part <NUM> of the present modified example can be applied to the head parts <NUM> of the following other embodiments.

As described above, a tensile force (pulling force) acts on the sleeve part <NUM> as a compressive force via the head part <NUM> when the tensile force acts on the shank part <NUM> according to the adhesive anchor 10A of the first embodiment. Since the sleeve part <NUM> is secured by the adhesive <NUM> filled between the sleeve part <NUM> and the anchor hole AH in this case, the anchor bolt 11A exerts a wedge effect on the concrete C at the head part <NUM>.

Further, since a tensile force (compressive force for the sleeve part <NUM>) acts on the sleeve part <NUM> from the tip end side via the head part <NUM>, the tensile force does not intensively act on the base end side (on the side of the opening part Ha) of the sleeve part <NUM> and failure (mushroom-shaped superposed failure) is not caused at a shallow portion of the concrete C. Accordingly, substantial tensile strength can be exerted at a shallower embedding depth over conventional art. Further, since the shank part <NUM> is not liable to be influenced by the adhesive <NUM>, its extension (toughness) can be fully used to support an object (structure).

Next, an adhesive anchor 10B according to a second embodiment will be described with reference to <FIG>. Note that the portion of the second embodiment different from that of the first embodiment will be mainly described. In this embodiment, an outer peripheral surface 16a of a sleeve part <NUM> of an anchor bolt 11B that contacts adhesive <NUM> is formed into an irregularity shape.

Specifically, the outer peripheral surface 16a of the sleeve part <NUM> is formed into an irregularity shape like the outer peripheral surface of a deformed bar. The irregularity shape in this case is only required to be one that contributes to the tensile strength of the anchor bolt 11B and may be an irregularity like, for example, a full thread. Further, the sleeve part <NUM> is anchored to a head part <NUM> by welding or the like in this case as well.

According to the adhesive anchor 10B of the second embodiment described above, substantial tensile strength can be exerted at a shallower embedding depth over conventional art and the extension (toughness) of a shank part <NUM> can be fully used to support an object (structure) like the first embodiment. Further, the shearing resistance of the adhesive <NUM> can be substantially exerted by the irregularity shape of the outer peripheral surface 16a of the sleeve part <NUM>, and the tensile strength can be further improved.

Next, an adhesive anchor 10C according to a third embodiment will be described with reference to <FIG>. Note that the portions of the third embodiment different from those of the first embodiment will be mainly described. In this embodiment, an anchor hole AH has a diameter expanded part Hd (bottom expanded part), and a head part <NUM> of an anchor bolt 11C has a mode adapted to the diameter expanded part Hd.

The anchor hole AH has a lower hole part H having a straight shape and the diameter expanded part Hd that is formed at the back of the lower hole part H. The diameter expanded part Hd has a tapered hole part Hda that is formed into a tapered shape and positioned on the side of an opening part Ha and a bottom expanded hole part Hdb that is formed into a straight shape. On the other hand, the anchor bolt 11C has the head part <NUM>, a shank part <NUM>, and a sleeve part <NUM> like the first embodiment.

The head part <NUM> in this case has, in an axial direction, a tapered surface part <NUM> on a base end side that has a tapered surface 23a, an intermediate column-shaped part <NUM>, and a guide surface part <NUM> on a tip end side that has a guide surface 21a. Further, the tapered surface part <NUM> faces the tapered hole part Hda of the anchor hole AH across adhesive <NUM> and has the same tapered angle as that of the tapered hole part Hda. Note that the tapered surface part <NUM> is not necessarily required to have the same tapered angle as that of the tapered hole part Hda.

Note that a method for constructing the adhesive anchor 10C according to the third embodiment is the same as that of the first embodiment. However, in a boring and cleaning step, the diameter expanded part Hd is formed at the hole back part of the anchor hole AH after the boring of the anchor hole AH (not shown). That is, the above bored anchor hole AH (straight hole) is a so-called prepared hole, and a diameter expansion drill bit attached to an electric drill is inserted into the prepared hole, and the hole wall Hc of the hole back part is ground to form the diameter expanded part Hd.

As described above, the anchor hole AH has the diameter expanded part Hd according to the adhesive anchor 10C of the third embodiment. Therefore, a tensile force (pulling force) that is applied to the head part <NUM> inside the diameter expanded part Hd can be caused to act not only on the adhesive <NUM> but also on concrete C via the tapered hole part Hda by the tapered surface part <NUM> in a dispersed manner. As a result, tensile strength can be improved as a whole.

Claim 1:
An anchor bolt (<NUM>) for an adhesive anchor (<NUM>) for fixing via adhesive (<NUM>) to an anchor hole (AH) formed in a fixed body, the anchor bolt (<NUM>) comprising:
a head part (<NUM>) for inserting into a hole back part of the anchor hole (AH);
a shank part (<NUM>) that is continuous with the head part (<NUM>) and formed to have a diameter smaller than a diameter of the head part (<NUM>); and
a sleeve part (<NUM>) into which the shank part (<NUM>) is inserted, the sleeve part (<NUM>) intended to extend from an opening part to the hole back part of the anchor hole (AH) and having a tip end thereof abutted onto the head part (<NUM>), wherein:
the head part (<NUM>), the shank part (<NUM>) and the sleeve part (<NUM>) are formed of steel or stainless steel,
the sleeve part (<NUM>) is anchored to the head part (<NUM>) by welding, adhesion, or screw connection,
an outer peripheral surface of the sleeve part (<NUM>) for securing by the adhesive (<NUM>) to contribute to tensile strength, and
an inner peripheral surface of the sleeve part (<NUM>) and an outer peripheral surface of the shank part (<NUM>) are not adhered or secured to each other.