JP2007063882A - High load bearing force anchor structure installed in expansion bore hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve extraction yield strength when shearing force acts in the 45-degree direction from a part on the concrete surface side of an expansion member positioned in a bore hole expansion hole by the expansion member of an anchor bolt tip part. <P>SOLUTION: An anchor bolt attached with the expansion member smaller than an inlet inner diameter of a bore hole on the tip and larger than an outer diameter of an anchor bolt when positioned in the bore hole expansion hole, is inserted into the bore hole of expanding a bore hole bottom part of hardened concrete. The expansion member is positioned in the expansion hole of the bore hole. An organic injection material or an inorganic injection material is filled in a bore hole void. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of a high load-bearing anchor that is attached to an expanded borehole at the bottom of a borehole of hardened concrete.

  In construction such as edge widening of concrete structures, jointing and alkali aggregate reaction countermeasures, etc., usually the perforations in the concrete structure are drilled and anchors are buried in the boreholes. Drilling concrete structures to the required depth using a rock drill or core cutter. After inserting the anchor bolt into the bore hole, the gap between the bore hole and the anchor bolt is filled with an organic injection material or an inorganic injection material.

  Such a method can be found in Patent Document 1, for example. In this method, the borehole diameter of the drilled concrete depends on the drill diameter to be drilled. When fixing the anchor bolt using the bore hole, insert an anchor bolt with an outer diameter slightly smaller than the bore hole diameter, fill the gap with an organic or inorganic injection material, and connect the anchor bolt with the bore hole inner wall. Adhere or adhere completely to each other.

Japanese Unexamined Patent Publication No. 2004-11345 Japanese Patent Application No. 2005-35773 Specification

  It is very common to insert an anchor into a borehole and inject concrete or adhesive into the borehole and fix the anchor to the borehole in construction work such as edge widening of concrete structures, jointing, and alkali aggregate reaction countermeasures. Has been done.

  Regardless of whether organic or inorganic, it is necessary to shorten the fixing length in order to exert the maximum capacity of the bolt against the anchor bolt pull-out force. could not. In addition, a fixing method using a borehole could not be performed under conditions where a continuous load such as prestress is always applied.

  The present invention intends to solve such problems as described below.

  The present invention provides the following means for solving the above problems.

  The present invention inserts an anchor bolt attached with an expansion member that is smaller than the inner diameter of the inlet of the bore hole and larger than the outer diameter of the anchor bolt when positioned in the bore hole expansion hole into the bore hole obtained by expanding the bottom of the bore hole of the hardened concrete. Provided is a high load-bearing anchor structure attached to an expansion borehole, wherein the expansion member is positioned in the expansion hole of the borehole and the borehole gap is filled with an organic injection material or an inorganic injection material.

  Specifically, an anchor bolt with a hexagon nut attached to the tip of the bore hole, which is smaller than the inner diameter of the bore hole and larger than the outer diameter of the anchor bolt, is inserted into the bore hole obtained by expanding the bottom of the bore hole of the hardened concrete. Provided is a high load-bearing anchor structure attached to an extended borehole, which is located in a borehole extended hole and is filled with an organic injection material or an inorganic injection material in a borehole space.

  Specifically, an anchor bolt with a mechanical anchor having an outer diameter smaller than the inner diameter of the borehole inlet is inserted into the borehole obtained by expanding the bottom of the hardened concrete borehole, and the mechanical anchor is positioned in the borehole expansion hole. Then, the high anchorage anchor structure attached to the expanded borehole is provided, wherein the tip of the mechanical anchor is expanded, and the borehole gap is filled with an organic injection material or an inorganic injection material.

  Specifically, an anchor bolt with a tapered nut attached at the tip is inserted into the bore hole obtained by expanding the bottom of the bore hole of the hardened concrete and having an outer diameter smaller than the inlet inner diameter of the bore hole and larger than the outer diameter of the anchor bolt. Provided is a high load-bearing anchor structure attached to an extended borehole, characterized by being positioned in a borehole extended hole and filled with an organic injection material or an inorganic injection material.

  Since the present invention is configured as described above, it has the following effects.

  5. The hardened concrete borehole is expanded at its bottom, and an extension member that is smaller than the borehole inlet inner diameter and larger than the outer diameter of the anchor bolt when positioned in the borehole extension hole is inserted into the borehole. Since the anchor bolt attached to the hole is inserted and the expansion member is positioned in the bore hole expansion hole, the expansion member at the tip of the anchor bolt is 45 degrees from the concrete surface side portion of the expansion member located in the bore hole expansion hole. A shearing force acts in the direction, and the pulling strength is improved.

  In addition, since the expansion member that is larger than the outer diameter of the anchor bolt is located in the bore hole expansion hole, the shear resistance is large, and the resistance force against the sustained load can be increased. You can also.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment in which the expansion member 4 is an ordinary hex nut 41.

  First, a bore hole 2 is drilled in the hardened concrete 1, and an expansion hole 2a is formed at the bottom.

  An anchor bolt 3 having a hexagonal nut 41 having an outer diameter smaller than the inlet inner diameter of the borehole 2 and larger than the outer diameter of the anchor bolt is inserted into the borehole 2, and the hexagonal nut 41 is positioned in the expansion hole 2a.

  Next, the gap 5 in the bore hole 2 is filled with the injection material 5, and the anchor bolt 3, the hexagon nut 41 and the inner wall of the bore hole 2 are bonded or closely attached.

  FIG. 2 shows an embodiment in which the expansion member 4 is a mechanical anchor 42.

  First, a bore hole 2 is drilled in the hardened concrete 1, and an expansion hole 2a is formed at the bottom.

  When the bore 2 is inserted, an anchor bolt 3 having a mechanical anchor 42 having an outer diameter smaller than the inner diameter of the inlet of the bore hole 2 is inserted into the bore hole 2, and the mechanical anchor 42 is positioned in the expansion hole 2a. The tip of 42 is expanded.

  Next, the gap 5 in the bore hole 2 is filled with the injection material 5, and the anchor bolt 3, the mechanical anchor 42 and the inner wall of the bore hole 2 are bonded or adhered.

  FIG. 3 shows an embodiment in which the expansion member 4 is a tapered nut 43.

  First, a bore hole 2 is drilled in the hardened concrete 1, and an expansion hole 2a is formed at the bottom.

  An anchor bolt 3 having a taper nut 43 attached at the tip thereof with an outer diameter smaller than the inlet inner diameter of the bore hole 2 and larger than the outer diameter of the anchor bolt is inserted into the bore hole 2, and the taper nut 43 is positioned in the expansion hole 2a.

  Next, the gap 5 in the bore hole 2 is filled with the injection material 5, and the anchor bolt 3, the taper nut 43 and the inner wall of the bore hole 2 are bonded or closely attached.

  In this way, a high load-bearing anchor structure attached to each expansion borehole is formed.

  In the above, the expansion of the bottom of the bore hole 2 may be performed, for example, by connecting a bit having a horizontal blade at the tip of the shaft, applying the bit to the peripheral wall of the bottom, and shaving the peripheral wall. Is connected to a tip of a hose connected to a compressor as proposed in Patent Document 2 with a perforation widening device having one end closed and a plurality of ejection holes penetrating from the inner wall around the shaft to the outer wall. It may be done by installing a blasting hook in the middle of the hose, operating the compressor, and blowing out the blasting material introduced into the blasting pot from the outlet hole of the drilling widening tool and scraping the bottom wall of the borehole. The widening method is not particularly limited.

  As the injection material, an epoxy resin or an acrylic resin material can be used as an organic material, and cement mortar, cement milk, or the like can be used as an inorganic material.

  4 and 5 are test diagrams showing an example of a pulling strength comparison test between the anchor structure according to the conventional example and the anchor structure according to the present invention, and FIGS. 6 and 7 are test result graphs.

  FIG. 4 shows that 450 mm of a reinforcing bar D51 anchor bolt 3 is embedded in the bore hole 2 of the hardened concrete 1, and FIG. 5 shows that an S35C M56 carbon steel taper nut 43 is inserted into the bore hole 2 with the bottom of the hardened concrete 1 as an expansion hole 2a. Attached anchor bolts 3 were embedded 450 mm, and each of the injection materials 5 was filled in the gaps of the bore holes 2. After the injection material 5 was cured, an anchor pull-out test was performed using a center hole jack and a beam-type loading jig.

  As a result, as shown in FIG. 6, the anchor structure shown in the conventional example is pulled out of the borehole before the maximum proof stress of the anchor is reached, and the concrete is destroyed. However, the anchor structure according to the present invention has the maximum proof strength of the anchor. The proof stress can be demonstrated without coming out of the borehole, and the pull-out load is large.

  4 and 5, 765 mm of the reinforcing bar D51 anchor bolt was embedded, and in FIG. 5, 450 mm of the anchor bolt 3 with the M56 carbon steel / taper nut 43 of S35C was embedded, and the same pulling test was performed.

  As a result, as shown in FIG. 7, both showed a pull-out load exceeding the maximum proof stress of the anchor. However, although the latter has a much shallower embedding depth, it is possible to secure a pulling load comparable to the former.

  4 and 5, the chain line indicates the fracture line of concrete, in FIGS. 6 and 7, the vertical axis indicates the pulling load (kN), the horizontal axis indicates the displacement (mm), and A indicates the reinforcing bar D51. Anchor bolts and B show the relationship between the load and displacement of S35C M56 carbon steel and anchor bolts with tapered nuts, respectively.

  As is clear from this experimental result, by positioning an expansion member larger than the diameter of the anchor bolt attached to the tip of the anchor bolt in the bottom expansion hole of the anchor bolt, the concrete fracture line is positioned at the expansion hole of the bore hole. A shearing force acts in the direction of 45 degrees from the portion on the concrete surface side of the expansion member to be performed, the fracture energy of the concrete is increased, and the pulling strength is improved.

  Since the present invention is configured as described above, an example of its use will be described below.

  FIG. 8 shows an example in which the present invention is applied to the edge widening work of the fallen bridge prevention structure.

  When the edge of the new concrete 6 is widened, a widening hole 2a is formed at the bottom of the bore hole 2 of the old concrete 1, an anchor bolt 3 having a widening member 4 is inserted, and the widening member 4 is positioned in the widening hole 2a. Shows where it was filled.

  Conventionally, an embedding depth of 15 times the anchor bolt diameter is required, but the embedding depth is not so deep in the present invention.

  The present invention can be used in this manner, and is effective for fixing a widening member that supports a large reaction force, an anchor structure that cannot secure a large embedding depth, and an anchor structure that introduces prestress.

  Needless to say, the present invention is not limited to the above-described embodiments.

It is sectional drawing which shows embodiment of the anchor structure which concerns on this invention. It is sectional drawing which shows another embodiment of the anchor structure which concerns on this invention. It is sectional drawing which shows another embodiment of the anchor structure which concerns on this invention. It is a test figure which describes an example of the drawing strength comparison test of the anchor structure by a prior art example. It is a test figure which describes an example of the drawing strength comparison test of the anchor structure which concerns on this invention. It is a drawing strength comparison test result graph of the anchor structure by a prior art example. It is a drawing strength comparison test result graph of the anchor structure concerning the present invention. It is the schematic which implemented this invention for the edge widening work of the fall bridge prevention structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concrete 2 Bore hole 2a Widening hole 3 Anchor bolt 4 Widening member 41 Hexagon nut 42 Mechanical anchor 43 Tapered nut 5 Injection material 6 New concrete

Claims (4)

  Insert an anchor bolt with an expansion member attached to the bore hole, which is smaller than the bore inner diameter of the bore hole and larger than the outer diameter of the anchor bolt when positioned in the bore hole expansion hole. A high load-bearing anchor structure attached to an extended borehole, wherein the borehole gap is filled with an organic injection material or an inorganic injection material.   Insert an anchor bolt with a hexagon nut attached to the tip of the bore hole, which is smaller than the inner diameter of the bore hole and larger than the outer diameter of the anchor bolt, into the bore hole that expands the bottom of the bore hole of the hardened concrete, and position the hexagon nut in the bore hole expansion hole. A high load-bearing anchor structure attached to an extended borehole, wherein the borehole gap is filled with an organic injection material or an inorganic injection material.   Inserted an anchor bolt with a mechanical anchor with an outer diameter smaller than the inner diameter of the bore hole into the bore hole, and the mechanical anchor is positioned in the bore hole expansion hole. A high load-bearing anchor structure attached to an extended borehole, wherein the tip of the anchor is expanded and the borehole gap is filled with an organic injection material or an inorganic injection material.   Insert an anchor bolt with a tapered nut attached to the tip of the bore hole, which is smaller than the inner diameter of the bore hole and larger than the outer diameter of the anchor bolt, into the bore hole with the bottom of the hardened concrete bore hole expanded, and position the tapered nut in the bore hole expansion hole. A high load-bearing anchor structure attached to an extended borehole, characterized by being filled with an organic injection material or an inorganic injection material.

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