JP2012141136A - Direct grip testing method and test jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly perform a breakage separation test of a columnar portion from a concrete surface without using adhesive in a testing method and a test jig of a structure allowed to be directly grasped, such as a concrete structure, asphalt pavement and a tile structure.SOLUTION: The test jig is composed of a cylindrical outside wedging member 10 and a plurality of inside wedging members 12 separately arranged along the inner periphery of the outside wedging member 10. The outside and inside wedging members 10, 12 are respectively provided with facing conical surfaces 10A, 12A. Predetermined force of a vertically separating direction is applied between the outside and inside wedging members 10, 12 and the inside wedging members 12 are displaced in the inner direction of a radius under wedging action between the conical surfaces 10A, 12A and pressure-welded to a concrete columnar portion 56. A clamp 62 of a construction research type tensile tester is connected to the outside wedging member 10, and a separation or breakage test of the concrete columnar portion 56 is performed by applying tensile force.

Description

  The present invention relates to a test method for an object to be inspected by a tensile tester or the like, and more specifically, a method and a test for performing a tensile test for separating or breaking by directly grasping the object to be inspected without using an adhesive. With regard to the jig, it is possible to perform a strength test on a structure that can be directly grasped, such as an asphalt pavement and a tile structure, in addition to a concrete structure by an external force such as tension or twist.

As a test for evaluating the strength of the surface layer portion of a concrete structure, there is a test in which a columnar concrete portion is broken and pulled out by a so-called pull-off method. In this test, an annular groove (recess) with a predetermined depth is drilled on the surface of the concrete under test, and a concrete columnar part formed inside the groove is used for connection with a clamp of a tensile tester. The cylindrical steel plate is covered as a tool, and the bottomed cylindrical steel plate is fixed to the columnar portion of the concrete with an adhesive such as an epoxy adhesive, and this cylindrical steel plate is connected to a clamp of a hydraulic tensile tester. By applying a tensile force from the tensile testing machine to the concrete columnar part via the clamp, the concrete columnar part is broken or separated, and the surface structure and deterioration state of the concrete are determined from the measured tensile strength at the time of failure. Evaluate. See, for example, Patent Document 1 for the pull-off method and its improved method.
JP 7-35667 A

  In the prior art, a columnar portion on the surface of the concrete to be tested is covered with a bottomed cylindrical steel plate as a jig for connecting to a clamp of a tensile tester, and is fixed to the columnar portion of the concrete with an adhesive. In order to obtain a predetermined bonding state between the jig and the concrete, it is necessary to wait for the adhesive to completely solidify. Therefore, a waiting time of at least 1 day, preferably 2 days is required, and a quick test request is required. I could not meet.

  The present invention has been made in view of this problem, and an object of the present invention is to enable a break separation test of an object to be inspected quickly without using an adhesive.

  In the direct grip test method of the present invention, by forming an annular groove having a predetermined depth from the surface side of the object to be inspected, leaving a portion of the object to be inspected in a columnar shape and generating a predetermined external force A test jig connected to the external force generation source is introduced into the annular groove, the test jig is brought into pressure contact with the columnar portion of the object to be inspected under wedge action, and an external force is applied to the test jig from the external force generation source. By doing so, the columnar part of the object to be inspected is broken or separated.

  The test jig for carrying out this method includes a cylindrical outer wedge-stop member having a constricted engagement surface on the inner peripheral surface, and a circumferential separation along the inner periphery of the outer wedge stop member. A plurality of inner wedge members each having a constricted engagement surface facing the engagement surface of the outer wedge stopper member on the outer peripheral surface, and the outer wedge member and the inner wedge member relative to each other. The inner wedge member is moved within the radius by the wedge action between the engagement surface on the outer periphery of the inner wedge stopper member and the engagement surface on the inner periphery of the outer wedge member by moving vertically in the separating direction. And an external force applying means for urging the inner wedge member against the columnar portion of the object to be inspected with a predetermined force, and the outer wedge member has a connecting portion with an external force generation source.

  The external force application means can be operated from the outside and a connecting means for connecting the inner wedge member and the outer wedge member so as to be relatively movable in the vertical direction while substantially preventing the inner wedge member and the outer wedge member from rotating. And an adjusting member that adjusts the wedge acting force by relatively moving the outer wedge-closing member up and down. And the connecting means is provided for each top wedge plate and the top plate disposed above the outer wedge stop member, the upper end is fixed to the top plate, and the middle is inserted through the outer wedge stop member so as to be vertically movable, A lower end can be comprised from the connection pin screwed together by a corresponding inner side wedge stop member. The wedge force adjusting member is constituted by a bolt loosely fitted to the top plate from above, and the lower end of the bolt is screwed to the outer wedge stopper member. In addition, a pair of connecting pins is provided for each inner wedge member at an interval in the circumferential direction, and the bolt is provided in the middle of the pair of connecting pins.

  In this invention, the test jig grips the object to be inspected under the action of a wedge, and does not require an adhesive for connection with the external force generation source, so that the necessary gripping force can be obtained, and it can be performed quickly and accurately. Inspection can be realized.

  In addition, the optimum design according to the situation is possible by adjusting factors such as the number of divisions of the inner wedge member, wedge angle and contact length, etc., and by providing a wedge force adjustment means such as a screw type, the optimum gripping is possible The force can be easily set.

FIG. 1 is a longitudinal sectional view of a test jig of the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a diagram schematically showing a concrete adhesion test (initial state of the test jig) using the test jig of the present invention. FIG. 6 is the same as FIG. 5, but shows a state in which the test jig is connected to the Kenken-type testing machine and pressed against the concrete columnar portion. FIG. 7 is a graph schematically showing the relationship between the wedge pressing force and the maximum tensile load.

  Hereinafter, although the case where this invention is implemented in the tensile strength test of the columnar part in the concrete surface is demonstrated, this invention can be implemented also in strength tests other than a tensile strength test, for example, the shear test by a twist. Moreover, it can be implemented not only in a concrete structure but also in a tile structure building as an object to be inspected.

1 to 4 show a test jig as an embodiment of the present invention. This test jig includes a clamp of a tensile tester (such as Kenken-type tensile tester) as an external force generation source of the present invention. As described later, the jig is introduced into an annular groove having a predetermined depth drilled in the surface of the concrete as an object to be inspected, and the cylindrical portion of the concrete inside the annular groove. Welded under the action of a wedge, the tensile force from the tensile testing machine is applied to the cylindrical part of the concrete, leading to the breaking and separation of the cylindrical part, and the adhesive strength and fracture strength are evaluated based on the measured values at that time. It can be carried out.
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  As shown in FIG. 1, the test jig includes an outer wedge member 10 and an inner wedge member 12. The outer wedge stop member 10 has a cylindrical shape with the upper end surface substantially closed and the lower end open. The outer wedge member 10 forms a conical surface 10A whose inner peripheral surface is constricted in the vicinity of the opened lower end (the constricted engagement surface of the outer wedge member of the present invention). As shown in FIG. 4, the inner wedge member 12 is formed by dividing a cylindrical part into a plurality of parts (four in this embodiment) along the circumferential direction. The cross section has an arc shape extending at an angle slightly less than 90 ° in the circumferential direction. As shown in FIG. 1, each inner wedge member 12 forms a conical surface 12A whose outer peripheral surface is constricted at the lower end portion (the constricted engagement surface of the inner wedge member of the present invention). The inner peripheral conical surface 10A of the outer wedge-clamping member 10 and the outer peripheral conical surface 12A of the inner wedge-clamping member 12 have the same angle, and the relative upper and lower surfaces of the outer wedge-clamping member 10 and the inner wedge-clamping member 12 shown in FIG. In the position (initial state = the inner wedge member 12 has no radial inward displacement), the outer circumferential conical surface 10A of the outer wedge member 10, the outer circumferential conical surface 12A of the inner wedge member 12, and the outer wedge member. The inner circumferential conical surface 10 </ b> A is in a positional relationship facing directly. When the inner wedge member 12 is displaced in the separation direction (relatively up and down displacement) by the external force with respect to the outer wedge member 10 from this initial position, the conical surfaces 10A and 12A ride on each other. Thus, the inner wedge stopper 12 is displaced radially inward (by the wedge action), and the inner wedge stopper 12 can be pressed against the concrete cylindrical portion and can be gripped. A certain gap δ (FIG. 4) is left between the adjacent inner wedge members 12, and relative movement of the inner wedge member 12 with respect to the outer wedge member 10 from the initial state of FIG. It is possible. And in order to improve the biting on the concrete surface, the inner peripheral surface 12B of the inner wedge-stopping member 12 is roughened (FIG. 1).

  According to the present invention, the connecting means for connecting the outer wedge member 10 and the inner wedge member 12 so as to be able to move relative to each other while preventing the rotation, and the outer wedge member 10 can be operated from the outside. An external force applying means comprising a wedge force adjusting member to be screwed is provided. As shown in FIG. 1, a circular top plate 14 is arranged above the outer wedge stopper 10. As shown in FIG. 4, each inner wedge member 12 is provided with two connecting pins 16 at both ends in the circumferential direction, that is, each inner wedge member 12. As shown in FIG. 1, the connecting pin 16 has a threaded portion 16-1 at the upper end. The threaded portion 16-1 is inserted into the top plate 14, sandwiches the top plate 14, and nuts 18 and 20 are screwed up and down. The upper ends of the connecting pins 16 are fixed to the top plate 14 by fastening the nuts 18 and 20 from above and below. FIG. 2 shows the upper nut 18. In FIG. 1, each connecting pin 16 is loosely fitted in a flaw hole 22 (see also FIG. 3) formed in the upper end wall 10-1 of the outer wedge member 10, and the lower thread portion 16-2 is an inner wedge member. It is screwed into the screw hole 25 (FIG. 4) of the member 12. The structure in which the top plate 14 is loosely fitted in the flaw hole 22 of the upper wall 10-1 of the outer wedge stopper 10 and screwed and fastened to the inner wedge stopper 12 constitutes the connecting means of the present invention. The inner wedge member 12 is connected to the outer wedge member 10 so as to be movable up and down. The relative downward movement of the inner wedge member 12 with respect to the outer wedge member 10 is a loose fit (backlash) of the flaw hole 22 that houses the connecting pin 16. ) Is appropriately set, the inner wedge stopper 12 can be moved radially inward due to the inclination of the conical surfaces 10A and 12A.

  Further, the bolt 24 (wedge force adjusting member of the present invention) is inserted into the hole 26 of the top plate 14 from the upper side, and the lower end 24-1 of the bolt 24 is connected to the upper wall 10-1 of the outer wedge stopper member 10 on the inside. It is screwed into a screw hole 28 formed at an intermediate position between the pair of connecting pins 16 for the wedge stop member 12 (see FIG. 3). The head 24A of the bolt 24 is positioned outside the top plate 14, and the outer wedge stopper 10 is lifted toward the top plate 14 by turning the bolt 24 with a tool (torque wrench) (the inner wedge stopper 12 is on the outer side). Accordingly, the inner wedge member 12 is displaced radially inward due to the inclination of the conical surfaces 10A and 12A. Further, a rattling stop spring 30 is disposed between the upper wall of the outer wedge stopper 10 and the top plate 14.

Then, in order to apply a tensile force from the clamp of the tensile tester to the jig, a sleeve-like connecting portion 32 having an inner thread is welded and fixed to the upper wall 10-1 of the outer wedge stopper member 10. Is loosely fitted in the flaw hole 34 of the top plate 14, and the tip protrudes from the top plate 14. As the tensile testing machine, a hydraulic type known as Kenken type (similar to that disclosed in Patent Document 1) can be used, and the clamp is inserted into the screw hole 32A of the connecting portion 32 as described later. It is screwed and a tensile force can be applied to the jig by hydraulic pressure.
With respect to the method for directly grasping and pulling the concrete surface with the test jig of the present invention, an example of measuring the grip strength of the concrete layer with respect to the steel plate deck in the bridge or the like will be described. In FIG. A concrete layer 52 is formed. Although the test jig has the structure shown in FIGS. 1 to 4 in detail, only the outer and inner wedge stopper members 10 and 12 are shown in a simplified manner for the sake of simplicity. Prior to the inspection, a hole is formed in the concrete layer 52 to reach the two concentric decks, large and small, and the concrete portion between them is destroyed and removed. As a result, an annular groove (dent) 54 reaching the deck 50 is formed. Therefore, a cylindrical concrete portion 56 is left inside the annular groove 54. Then, a test jig composed of the outer and inner wedge stoppers 10 and 12 is introduced into the annular groove 54. At this time, the inner wedge stopping member 12 is in an initial position where the amount of protrusion to the inside of the radius is zero, so that the inner wedge stopping member 12 is separated from the opposing surface of the concrete columnar portion 56 by some distance.

  By rotating the bolt 24 of FIG. 1 with a torque wrench, a force in the direction of an arrow between the outer and inner wedge members 10, 12 of FIG. 5 acts, and the inner wedge member 12 is relative to the outer wedge member 10. The inner wedge member 12 is displaced radially inward by the guiding action (wedge action) between the inclined surfaces 10A and 12A. Finally, the inner wedge member 12 is shown in FIG. In this way, it can be brought into pressure contact with the peripheral wall surface of the columnar concrete portion 56 and can be brought to a set tightening force (= fSET) by a torque wrench for tightening the bolt 24. Four inner wedge members 12 are provided in the circumferential direction, and the respective bolts are provided so that each inner wedge member 12 can be evenly bitten in the circumferential direction with respect to the columnar concrete portion 56. Individual adjustments of 24 clamping forces (= fSET) are made. The gripping force between the inner wedge-stopping member 12 and the columnar concrete portion 56 is in a proportional relationship as will be described later.

  In this way, after fixing the test jig composed of the outer and inner wedge members 10 and 12 to the cylindrical concrete portion 56 under the wedge action, the fracture test of the cylindrical concrete portion 56 by a tensile tester is performed. Is done. As a tensile tester, a commercially available Kenken type can be adopted, for example, a product manufactured by Sanko Electronic Laboratory Co., Ltd. can be adopted. This tensile tester is designated by reference numeral 60 in FIG. The clamp fitting 62 is provided, the leg 64 of the main body of the tensile tester is placed on the concrete surface, and the clamp fitting 62 is screwed onto the female thread portion 32A of the connecting portion 32 of the outer wedge stopper 10. By combining, the tensile tester and the test jig of the present invention can be easily connected. As is well known, the clamp fitting 62 is connected to the hydraulic mechanism inside the main body, and the pulling force can be increased by turning the handle 66 as shown by the arrow m. If the gripping force between the inner wedge member 12 and the cylindrical concrete portion 56 exceeds the adhesive force of the concrete portion 56 to the deck 50, the concrete portion 56 will eventually be separated and destroyed from the deck, The gripping force can be measured by the display on the display unit 68 at that time.

  Fig. 7 schematically shows the relationship between the wedge pressing force (bolt tightening force = wedge force) and the maximum tensile load (the tensile load value when overcoming the gripping force under the wedge force). A maximum tensile load that increases proportionally is obtained. The maximum tensile load is also proportional to the contact area between the inner wedge-stopping member 12 and the columnar concrete portion 56, and a large maximum tensile load can be obtained by increasing the contact area. Line a schematically shows a case where the contact surface is small and line b is large. Therefore, it goes without saying that the wedge pressing force and the contact area must be designed so that the maximum tensile load suitable for the test object is obtained.

  Moreover, although embodiment described above has demonstrated the test for the adhesive strength of the concrete layer with respect to a deck surface, it can be used similarly for the strength test of concrete itself. In addition, the object to be inspected is not only concrete but also asphalt, which can be used for measuring the adhesion strength of asphalt to the concrete surface and the strength of asphalt itself. Moreover, by drilling in the deck (iron plate), it can be used for measuring the adhesion strength of the deck to the concrete layer. Furthermore, the present invention can be used not only for road surface materials but also for other various inspection objects such as rocks and earth blocks, and also for building wall strength tests.

  Further, in the above embodiment, the columnar portion of the object to be inspected that is gripped by the test jig assumes a circular cross section, but is not necessarily limited to a circular cross section, and a rectangular cross section if a wedge force can be used. Can also be implemented.

DESCRIPTION OF SYMBOLS 10 Outer wedge stop member 10A Conical surface 12 of outer wedge member 12 Inner wedge member 12A Conical surface 14 of inner wedge member Top plate 16 Connecting pin 24 Bolt (wedge force adjusting member of the present invention)
30 Backlash spring 32 Connecting portion 50 Steel plate deck 52 Concrete layer 54 Annular groove (dent)
56 Cylindrical concrete part 60 Tensile tester 62 Clamp fitting

Claims (6)

  A test jig connected to an external force generation source for generating a predetermined external force by forming an annular groove of a predetermined depth from the surface side on the inspection target, leaving a part of the inner inspection target in a columnar shape Is introduced into the annular groove, the test jig is brought into pressure contact with the columnar portion of the object to be inspected under the action of a wedge, and an external force is applied to the test jig from an external force generating source to thereby form the columnar portion of the object to be inspected. A direct gripping test method characterized in that it leads to breakage or separation.   A test jig for carrying out the method according to claim 1, wherein the cylindrical outer wedge-shaped member having a constricted engagement surface on the inner circumferential surface, and along the inner circumference of the outer wedge-shaped member. A plurality of inner wedge members, each of which has a constricted engagement surface facing the engagement surface of the outer wedge member on the outer circumferential surface, and the outer wedge member; The inner wedge member is moved under the wedge action between the engagement surface on the outer periphery of the inner wedge stopper member and the engagement surface on the inner periphery of the outer wedge stopper member by moving the inner wedge member relatively upward and downward. An external force applying means for displacing the stop member inwardly in the radius and pressing the inner wedge member against the columnar portion of the object to be inspected with a predetermined force; the outer wedge member is connected to an external force generation source A test jig characterized by having a portion.   In the invention according to claim 2, the external force applying means includes a connecting means for connecting the inner wedge member and the outer wedge member so that the inner wedge member and the outer wedge member are substantially non-rotatable so as to be movable relative to each other in the vertical direction. A test jig comprising: an adjustment member that adjusts the wedge acting force by moving the outer wedge member relative to the inner wedge member in the vertical direction.   In the invention according to claim 3, the connecting means is provided for each of the inner plate and the top plate disposed above the outer wedge member, the upper end is fixed to the top plate, and the middle is the outer wedge member. And a connecting pin which is inserted into the inner wedge member so that the lower end thereof is screwed into the corresponding inner wedge stopper member.   5. The test jig according to claim 4, wherein the wedge force adjusting member is constituted by a bolt loosely fitted to the top plate from above, and a lower end of the bolt is screwed to the outer wedge-fastening member. .   6. The test jig according to claim 5, wherein a pair of connecting pins are provided at intervals in the circumferential direction for each inner wedge stop member, and the bolts are provided between the pair of connecting pins. .

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