JP2008275319A - Portable longitudinal elastic modulus measuring device, longitudinal elastic modulus measuring method, and breaking strength measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce expenses for tests and to perform optimum restoration and repair at site by measuring the Young's modulus and the breaking strength of the existing structure in real time at a site. <P>SOLUTION: The measuring device includes a portable load applicator for applying a bending load to the free end of a body to be tested having a cantilever structure formed in an object to be measured by drilling the object from its surface while leaving a columnar body, a load detector for detecting the load, a displacement detector for detecting the displacement of the body to be tested caused by the load, and a converter for converting the displacement into a Young's modulus. The object to be measured may be an artificial structure constructed of concrete, asphalt concrete, or wood, or a non-artificial structure such as a rock bed and a tree. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used for diagnosis of existing artificial structures made of solid objects such as concrete, asphalt concrete, and wood, and existing non-artificial objects (hereinafter referred to as measurement target objects) that are solid objects such as bedrock and trees. The present invention relates to a longitudinal elastic modulus measuring device and a breaking strength measuring method. In particular, in a place where an artificial structure or non-artificial object that is a measurement target object is located, a portable longitudinal elastic modulus measurement device that loads a necessary load on a test body formed on the measurement target object and measures a longitudinal elastic modulus, a load The present invention relates to a method for measuring longitudinal elasticity and a method for measuring breaking strength using bending deformation of a test specimen at the time of loading.

  Conventionally, as a method of measuring the longitudinal elastic modulus and measuring the breaking strength for diagnosing existing structures (objects to be measured), a cylindrical specimen (diameter: 100 mm x length: 200 mm) from the object to be measured ) Is collected and taken back to the measuring room, and the longitudinal elastic modulus and the breaking strength are generally measured using a universal testing machine.

The universal testing machine used here measures the elastic modulus and breaking strength of the material constituting the structure by a compression or tensile test, and the test specimen used is the above-described cylindrical specimen. In order to measure the compressive strength using this specimen, it is necessary to load 400 kgf / cm ² on the specimen. In order to measure the breaking strength by a tensile test, it is necessary to load 30 kgf / cm ² . To load such a load, external power such as hydraulic pressure is required.

  In addition, in the conventional measurement method, it is necessary to collect a cylindrical specimen, and the dimensions are large: diameter: 100 mm × length: 200 mm. For this reason, a large collection trace remains in the structure, and the sampled cylindrical specimen must be taken back to the measurement room, so that the longitudinal elastic modulus and breaking strength of the structure cannot be measured in real time on site. there were. In addition, this has a problem that optimal recovery activities cannot be performed on the spot according to the situation at the site.

  Further, since the test body must be brought back to the measurement room, there is a problem that the transportation cost is high, and the test cannot be performed unless an expensive and large universal tester is used.

  As a method of measuring compressive strength by collecting specimens with a diameter smaller than the standard, several small diameter cylindrical specimens with a diameter of 15 to 30 mm and a length approximately twice the diameter are collected from the concrete structure, and the small diameter circle is obtained. There has been proposed a technique for estimating a longitudinal elastic modulus and a breaking strength of a structure from an average value of a compression test over a plurality of columnar specimens (Patent Document 1).

  However, the cylindrical specimens collected by this technology must also be subjected to a measurement of longitudinal elastic modulus and a test of breaking strength by a compression test using a conventional universal testing machine. There is a problem that the measurement of the longitudinal elastic modulus and the test of the breaking strength cannot be performed.

As a method for solving the above problem, a longitudinal elastic modulus of the object to be measured is formed by forming a cylindrical specimen having a diameter of 45 mm × length: about 90 mm to 135 mm on the object to be measured, and subjecting this specimen to a torsion test. A technique for estimating the torsional strength in the field has been proposed (Patent Document 2). However, in this technique, the elastic modulus that can be directly measured is the shear elastic modulus, and there is a problem that the Poisson's ratio must be assumed to be an appropriate value in order to obtain the longitudinal elastic modulus.
Japanese Patent No. 3067016 Japanese Patent Application No. 2004-081786

  Therefore, an object of the present invention is to make it possible to directly measure the longitudinal elastic modulus and the breaking strength necessary for diagnosing a structure at a site where an existing artificial structure such as concrete or an existing non-artificial object such as a rock is located. An object of the present invention is to provide a longitudinal elastic modulus measuring apparatus, a longitudinal elastic modulus measuring method using the same, and a breaking strength test method.

(1) The present invention is a portable type in which a columnar body remains perforated from the surface of a measurement target object, and a bending load is applied to one end of an open end of a cantilever structure test body formed in the measurement target object. A load loader; a load detector for detecting the load; a displacement detector for detecting a displacement generated in the specimen by the load; and a converter for converting the displacement into a longitudinal elastic modulus. Features. A cylindrical test body is formed into a cantilever beam by a core drill or the like on an object to be measured such as a structure, and bending deformation is caused by applying a concentrated load to one end of the open end of the cantilever beam. With a converter that converts the longitudinal elastic modulus of the structure from the value of the load applied by the portable load tester and the displacement caused by the bending deformation, the longitudinal elastic modulus of the object to be measured is collected without taking the test specimen and taking it home. Can be measured directly.
(2) The measurement object is preferably an artificial structure constructed of concrete, asphalt concrete, wood, or the like, or a non-artificial object such as a rock mass or a tree.
(3) The present invention drills so that a columnar body remains from the surface of the object to be measured, forms a test body with a cantilever structure in the object to be measured, and applies a bending load to the open end of the test object. Bending deformation is generated, and the displacement generated by the deformation is converted into a longitudinal elastic modulus of the object to be measured.

  The present invention is characterized in that the breaking strength of the object to be measured is measured by applying the load described in (3) above until the specimen is broken.

According to the portable longitudinal elastic modulus measuring device of the present invention, the longitudinal elastic modulus can be directly measured at the site where the measurement target object is located without using external power such as hydraulic pressure. Further, by increasing the load by the portable load tester according to the present invention until the test body breaks and determining the value of the load at the time of the break, the break strength of the object to be measured can be measured in the field. .

  Embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a view showing a state in which a cylindrical test body 11 is formed on an object 10 to be measured. The cylindrical specimen 11 may be formed by using a commercially available core drill. In the prior art, a solid cylindrical body (test body 11) is formed after a solid large-diameter hole is provided in the object 10 by a core drill having a cylindrical drill bit having a diamond tip at the tip. A cylindrical specimen having a diameter of 100 mm and a length of 200 mm is obtained from the object 10 to be measured and used in a universal testing machine.

  In the present embodiment, until the drilling is performed using the cylindrical drill bit, there is no difference from the conventional method of using the core drill, but the test object 11 is not broken and the measurement target object 10 is left as it is. It is characterized by leaving it behind.

  FIG. 2 shows a state in which the test body 11 is left on the measurement target object 10 and the cylindrical test body 11 formed on the measurement target object 10 in the field is regarded as a cantilever loaded with a load. As shown in FIG. 2, by applying a load on site, the test body 11 is in a bending deformation state and can be displaced.

  The displacement is recorded while changing the magnitude of the loading load at the site where the measurement object 10 is located, and the load is applied to the open end of a cantilever beam that is generally known by a known method, that is, structural mechanics. If the relational expression between the load and deflection at the time of loading is applied as a conversion formula, the longitudinal elastic modulus can be measured at the site. At this time, the time for continuously recording the displacement while applying the load is about 5 to 10 minutes, and if the above conversion formula is stored in a storage / calculation device such as a notebook personal computer in advance, Thus, the longitudinal elastic modulus can be obtained.

  In the above description, it is assumed that the magnitude of the loaded load is within the elastic deformation range of the object 10 to be measured. However, it is also possible to record the load at the time of breakage by increasing the value of the loaded load until the test piece breaks. Thereby, the breaking strength can be measured. Since it is only necessary to know the magnitude of the load at the time of fracture, the test can be performed even if measurement of displacement is omitted.

  FIG. 3 is a diagram showing components constituting a portable longitudinal elastic modulus measuring apparatus according to an embodiment of the present invention. As shown in FIG. 3, the portable longitudinal elastic modulus measuring device according to the embodiment of the present invention includes a portable load loader 30 and a load detector 31 for detecting the load loaded by the portable load loader 30; What is necessary is just to be comprised by the displacement detector 32 for detecting the displacement by the bending deformation which arose in the test body 11. FIG.

The method of measuring the longitudinal elastic modulus is slightly different depending on the material of the object to be measured 10 shown in FIG. 3 and the dimensions of the formed cylindrical test body 11, but here the diameter and length of the test body 11 are different from those of the prior art. A case of a small size (diameter: 45 mm × length: about 113 mm to 158 mm) will be described.
In the actual site, as shown in FIG. 1, the measurement target object 10 exists around the test body 11 formed on the measurement target object 10, but in FIG. 3, the longitudinal elasticity of the present invention is present. In order to explain the coefficient measurement method in an easy-to-understand manner, the measurement object 10 is omitted from the periphery of the test body 11.

  The test body 11 and the measurement target object 10 illustrate the state in which only the bottom surface of the test body 11 is integrated with the measurement target object 10 in order to emphasize that the test body 11 has a cantilever shape. The components necessary for measuring the longitudinal elastic modulus according to the present invention are separately shown around the.

  In FIG. 3, the load detector 31 is located between the portable load loader 30 and the test body 11. However, if the load detector 31 can detect the load generated by the portable load loader 30, It is not limited to. The installation position can be appropriately changed according to the material of the measurement object 10, the dimensions of the test body 11, and the situation at the site.

  FIG. 4 is a view for explaining the operation of the portable load loader 30. FIG. 4 (a) shows details of the portable load loader 30. FIG. The outline of the operation at the time of loading is that a predetermined loading force can be obtained by rotating the loading handle 400 and moving the slide body 410 in parallel with respect to the fixed body 411. That is, the loading handle 400 is connected to the handle bracket 401 through the through hole 402, while the handle bracket 401 is fixed to the main screw 404.

  Therefore, by rotating the loading handle 400, the main screw 404 also rotates, and the slide body 410 moves relative to the fixed body 411 by the action of the main screw receiving female screw 405 provided on the slide body 410. Become. Further, the main screw 404 is sandwiched between an upper slide pin 406 and a lower slide pin 407 that are mounted in parallel to the fixed body 411. The slide body 410 has an upper slide pin receiving hole 408 and a lower slide pin receiving hole 409. Therefore, the slide body 410 operated by the rotation of the main screw 404 is relatively moved in parallel.

  In addition, the main screw 404, the upper slide pin 406, and the lower slide pin 407 have sufficient rigidity with respect to the load to be loaded (maximum of about 100kgf). The curvature tooth 412 for loading the load and the flat tooth 413 for sharing the reaction force upon loading can also move in parallel. In addition, since the curvature tooth 412 that is in direct contact with the test body 11 has a curvature, it is easy to manage the contact state with the test body 11.

  The handle stoppers 403 provided at both ends of the loading handle 400 are for preventing the loading handle 400 from falling off the handle bracket 401. FIG. 4 (b) shows a photograph of the prototype loader 30.

  Fig. 5 shows the measurement object 10 made of mortar with a core drill using a cylindrical drill bit with an outer diameter of 52 mm × inner diameter: 45 mm × effective drilling depth: 300 mm with a diamond tip at the tip. Diameter: 45 mm × length : A state in which a cylindrical test body 11 of about 113 mm to 158 mm is formed, and a space 12 for accommodating the portable load loader 30 and the load detector 31 adjacent to the test body 11 and having a diameter of 32 mm It shows a state where a drill bit is drilled to a depth of about 30 mm. At this time, the perforation protrusion 13 is formed, but this has hindered the storage of the portable load loader 30 and the load detector 31. It was decided to remove it by striking.

  FIG. 5 (b) shows a cross section of the test body 11 and the storage space 12 formed on the object 10 to be measured. FIG. 6 shows a state after the perforation protrusion 13 shown in FIG. 5 is removed. FIG. 6 (a) shows that a cylindrical test body 11 is formed on a measurement object 10 made of mortar, and the storage space for the portable load loader 30 and the load detector 31 is connected linearly. . FIG. 6 (b) shows a photograph actually formed.

  FIG. 7 shows a state in which a test for measuring the longitudinal elastic modulus is being performed. By rotating the loading handle 400 of the portable load loader 30 stored in the storage space 12, a load acts on the curvature tooth 412, and the flat tooth 413 takes charge of the reaction force, and the load at that time is detected. The instrument 31 is measuring. Then, bending deformation is generated in the cylindrical test body 11 having a diameter of 45 mm × length of about 113 mm to 158 mm formed on the measurement object 10 made of mortar, and the displacement detector 32 measures the displacement at that time. ing.

  Here, the measurement object 10 and the cylindrical specimen 11 formed thereon are mortar, and the dimensions of the cylindrical specimen 11 are diameter: 45 mm × length: about 113 mm to 158 mm, Here, in order to test the method of measuring the longitudinal elastic modulus and the breaking strength, the load detector 31 is a product name: compression micro load cell manufactured by Tokyo Sokki Kenkyujo Co., Ltd., product number: CLS-2KNA. In addition, as the displacement detector 32, a product name: clip type displacement meter manufactured by Tokyo Sokki Kenkyujo Co., Ltd., product number: UB-2 was used.

  However, as described above, the displacement detector 32 can be omitted because it is sufficient that only the magnitude of the load at the time of breaking can be measured in the breaking strength test. In addition, as a restriction on the use of the load detector 31 used here, the bottom surface is in contact with a flat surface in order to accurately detect the loaded load. Therefore, in this embodiment, this condition is satisfied by using the crank plate 14.

  FIG. 8 shows the details of the crank plate 14. This crank plate 14 is composed of a flat plate portion 15 that is in direct contact with the load detector 31 and a handle 16 provided so as to be easily installed in the storage space 12, and the performance required for the crank plate 14 is broken. The flat plate part 15 has a rigidity that does not deform even when a load of a magnitude for testing the strength is loaded. This is because the crank plate 14 has a strength of about SS41, which is a general structural steel. If you have it, you can achieve it well. The crank plate 14 may be made according to the size of the storage space 12, but it needs to have a thickness of about 1 to 2 mm.

  FIG. 9 is a photograph showing an actual state when the longitudinal elastic modulus is measured. Here, the load handle 400 of the portable load loader 30 is extended and rotated by a wrench so that the load can be easily loaded.

  FIG. 10 shows the results when loading was performed in the above-described manner, the amount of displacement when the specimen 11 was bent and deformed on the horizontal axis, and the magnitude of the loaded load on the vertical axis. The relationship between the deflection (displacement) and the load is plotted, and the relationship between the deflection and the load at that time is obtained by an approximate straight line 100 by the least square method or the like, and the slope 101 is obtained on the spot.

  The straight line slope 101 can be converted into a longitudinal elastic modulus by a known conversion formula. Furthermore, assuming that the measurement target object 10 is isotropic, the Poisson's ratio can be derived from the shear elastic modulus obtained from Patent Document 2.

  Table 1 shows that for the same object 10 to be measured, the diameter D of the test body 11 was fixed to 45 mm, and the length L of the test body 11 was set to about 113 mm, 135 mm, and 158 mm to obtain the longitudinal elastic modulus. It is a result. The ratio L / D between the diameter dimension D and the length dimension L of these specimens 11 corresponds to about 2.5, 3 and 3.5, respectively, but all values are averages of the results of measurements 20 to 30 times. It was confirmed that it was almost the same as the value of about 21 GPa of the longitudinal elastic modulus obtained by the conventional compression test.

  According to the portable load tester of the present invention, it is possible to easily measure the longitudinal elastic modulus and breaking strength of a structure in real time in the field. And may be used for repair work.

Explanation of symbols

10 Object to be measured
11 Specimen
30 Portable loader
31 Load detector
32 Displacement detector
400 Loading handle
401 Handle bracket
402 Through hole
403 Handle stopper
404 main screw
405 Main screw receiving female screw
406 Upper slide pin
407 Lower slide pin
408 Upper slide pin receiving hole
409 Lower slide pin receiving hole
410 slide body
411 fixed body
412 curvature teeth
413 flat teeth
12 Storage space
13 Drilling protrusion
14 Crank plate
15 Flat plate section
16 Handle
100 approximate line
101 Slope of approximate line

It is the figure which showed the cylindrical test body formed in the measurement object. It is the figure which showed the state which caught the cylindrical test body formed in the measurement object as a cantilever beam with which load was loaded. It is the figure which showed the component apparatus of the portable longitudinal elastic modulus measuring apparatus used by the present Example. It is the figure which showed the detail for demonstrating the operation | movement of the portable load carrier used in a present Example. It is the figure which showed the test body formed in the measurement object used in a present Example, and the storage space provided adjacent to the test body. It is the figure which showed the state shape | molded by removing the perforation | projection protrusion part in the storage space used in a present Example. The mode during the measurement of the longitudinal elastic modulus in a present Example is shown. It is the figure which showed the detail of the crank plate used in a present Example. The photograph in the longitudinal elastic constant measurement of a present Example is shown. The relationship figure of the deflection amount measured in a present Example and the magnitude | size of a loaded load is shown.

Claims (4)

A portable load loader that applies a bending load to the open end of the test body of the cantilever structure in the measurement target object formed by drilling so that the columnar body remains from the surface of the measurement target object;
A load detector for detecting the load;
A displacement detector for detecting displacement generated in the specimen by the load;
A portable longitudinal elastic modulus measuring apparatus comprising a converter for converting the displacement into a longitudinal elastic modulus.   2. The portable longitudinal elastic modulus measurement according to claim 1, wherein the object to be measured is an artificial structure constructed of concrete, asphalt concrete, wood, or the like, or a non-artificial structure such as a bedrock or a tree. apparatus. Drilling so that the columnar body remains from the surface of the object to be measured, forming a test body with a cantilever structure,
Bending deformation is generated by applying a bending load to the open end of the specimen,
A method of measuring a longitudinal elastic modulus, wherein the displacement caused by the deformation is converted into a longitudinal elastic modulus of the object to be measured.   A breaking strength measuring method, wherein the breaking strength of the structure is measured by applying the load according to claim 3 until the specimen breaks.