JP2010066154A - Method for mounting sensor element to concrete structure and method for inspecting quality of concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for mounting a sensor element to a concrete structure and a method for properly inspecting quality of a concrete structure for existing concrete structures. <P>SOLUTION: A rodlike reinforcement 7 with sensor elements 10A, 10B, 10C mounted thereon, in which electrical energy and mechanical energy are convertibly converted, is previously prepared, and the reinforcement 7 with the sensor elements 10A, 10B, 10C mounted thereon is inserted into a small diameter hole 5 that is bored into an existing concrete structure 3 and thereafter the small diameter hole 5 is filled with a filler 3a. Mechanical vibration, in the condition that an oscillator 11 is brought into contact with the outside surface of the concrete structure 3, is generated by applying an oscillating signal to the oscillator 11. With this mechanical vibration, an elastic wave propagating in the concrete is detected by the sensor elements 10A, 10B, 10C, as a received vibration signal. The quality of the concrete structure 3 is inspected by calculating the propagation speed of the elastic wave from the phase difference between the oscillated signal and the received vibration signal determined in that case. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for attaching a sensor element to an existing concrete structure and a concrete structure quality inspection method for nondestructively inspecting the quality (plate thickness, internal peeling, cracks, etc.) of the concrete structure.

Conventionally, a technique for inspecting the quality of an existing concrete structure or the like in a nondestructive manner is widely known.
For example, in Patent Document 1, an ultrasonic train emitted from one ultrasonic probe disposed oppositely on an article is received by the other ultrasonic probe, and the propagation time is measured from the distance between the probes. -A so-called face-to-face method has been proposed, in which the presence or absence of internal defects of an article is inspected from the propagation speed of an ultrasonic train calculated for each measured propagation time.
Further, in Patent Document 2, by performing echo reception while moving either or both of the transmitting probe and the receiving probe arranged on the surface of the existing concrete structure, A so-called surface method has been proposed that can accurately measure the plate thickness and internal defects regardless of the presence or absence of obstacles in the concrete.

JP-A-5-107233 JP 2004-184276 A

However, even if the inspection method proposed in the above publication is a face-to-face method with excellent propagation ability, when the concrete structure to be inspected is thick, the elastic wave energy transmitted from one ultrasonic probe is It may be attenuated and not received by the other ultrasonic probe, and measurement may not be performed. Although it is conceivable to increase the transmission power in order to make it possible to measure, there is still a limit, and when the power is increased, the apparatus body becomes larger, the manufacturing cost increases, and the inspection cost increases.
In addition, the facing method in which two ultrasonic probes are arranged to face each other with a measurement point sandwiched between them, for example, when an outer wall or an upper floor is present adjacent to the measurement point, one ultrasonic probe cannot be applied. Therefore, measurement may not be possible.

  The present invention has been made in view of such circumstances, and provides a method for attaching a sensor element to an existing concrete structure, and even if the concrete structure is thick, the quality inspection of the concrete structure is provided. It is another object of the present invention to provide a method for inspecting the quality of a concrete structure that can perform inspection without being influenced by the situation of the measurement location.

The above object of the present invention is achieved by the following configuration.
(1) preparing a rod-like body to which a first sensor element capable of reversibly converting electrical energy and mechanical energy is attached;
Forming a small-diameter hole in an existing concrete structure;
Inserting the rod-like body having the sensor element attached thereto into the small-diameter hole, and then filling the small-diameter hole with a filler to embed the sensor element in concrete. How to attach to the structure.

  According to the said method, even if it is an existing concrete structure, a sensor element is attached and a quality inspection of the existing concrete structure can be performed.

(2) A plurality of the first sensor elements are arranged apart from the rod-like body, and an oscillation signal having a constant frequency is applied to one sensor element to generate mechanical vibration. A sensor wave is detected by another sensor element, and a phase difference between the vibration receiving signal obtained at that time and an oscillation signal applied to the one sensor element is obtained, and the obtained phase difference and the separation distance between the sensor elements Then, the propagation speed of the elastic wave is calculated, and the expression of strength of the filler is inspected. (1) The method of attaching the sensor element to a concrete structure according to (1).

  According to the above method, the strength development of the filler filled in the small-diameter hole can be inspected by calculating the propagation speed of the elastic wave propagating through the concrete. If the development of strength is confirmed and the filler material has the same strength as the existing concrete structure, the sensor element is placed in the structure before placing the concrete and is placed in the concrete after placing. A quality inspection equivalent to the quality inspection can be performed.

(3) including a step of restricting the position of the rod-shaped body by bringing at least a part of the rod-shaped body into contact with the inner wall of the small-diameter hole;
(1) The method of attaching a sensor element to a concrete structure according to (1), wherein the first sensor element is disposed apart from an inner wall of the small-diameter hole.

  According to the above method, the sensor element is arranged at the center of the hole spaced from the inner wall of the small-diameter hole, thereby avoiding the influence of the contact with the existing concrete structure and developing the strength of the filler to be filled. Can be inspected with high accuracy.

(4) The second sensor element capable of reversibly converting electrical energy and mechanical energy while performing the method of attaching the sensor element of (1) to (3) to a concrete structure, or an oscillation capable of generating an elastic wave An oscillating signal is applied to either the second sensor element, the oscillating element or the first sensor element in a state where the element or a receiving element capable of receiving an elastic wave is applied to the outer surface of the concrete structure. The first sensor element, the second sensor element, or the receiving element detects an elastic wave that propagates through the concrete due to the mechanical vibration, and the received vibration signal and the first 2 is obtained, and the phase difference from the oscillation signal applied to the sensor element 2 or the oscillation element or the first sensor element is obtained, and the obtained phase difference is applied to the outer surface of the concrete structure. Further, from the distance between the second sensor element, the oscillating element or the receiving element and the first sensor element disposed in the concrete structure, the propagation speed of the elastic wave is calculated to perform quality inspection. A method for inspecting the quality of a concrete structure, characterized in that it is performed.

  According to the above method, the oscillation signal applied to either the second sensor element, the oscillation element or the first sensor element and the oscillation signal are received by the first sensor element, the second sensor element or the reception element. In the concrete based on the phase difference from the received vibration signal and the separation distance between the first sensor element in the concrete structure and the second sensor element, the oscillation element or the vibration receiving element on the surface of the concrete structure. The velocity of the propagating elastic wave is obtained, and when the velocity of the elastic wave is significantly slower than that of sound concrete, it can be determined that there is a defect including a crack. That is, the propagation speed in a sound existing concrete structure is generally around 4000 m / s, but if the air layer is included due to cracks, defects, etc., the propagation speed tends to be reduced to about half. By detecting this, it is possible to inspect the presence or absence of a defect or the like. Moreover, the effect of repair can be confirmed by detecting the propagation speed after repairing a defect etc.

(5) The method for attaching the sensor element of (1) to (3) to the concrete structure is applied to each of at least two small-diameter holes formed at positions on the concrete structure spaced apart by a predetermined distance. An oscillation signal is applied to the sensor element embedded in the small-diameter hole to generate mechanical vibration, and an elastic wave propagating in the concrete due to the mechanical vibration is detected by the sensor element embedded in the second small-diameter hole. The phase difference between the vibration signal obtained from time to time and the oscillation signal applied to the sensor element embedded in the first small-diameter hole is obtained, and the propagation of the elastic wave is obtained from the obtained phase difference and the separation distance between the small-diameter holes. A method for inspecting the quality of a concrete structure, characterized by calculating a speed and inspecting the quality of the existing concrete structure.

  According to the above method, the phase difference between the oscillation signal applied to the sensor element embedded in the first small-diameter hole and the received signal obtained by receiving the oscillation signal with the sensor element embedded in the second small-diameter hole, Since the propagation speed of the elastic wave propagating in the concrete is obtained based on the separation distance between the first and second small-diameter holes, the member thickness of the existing concrete structure is too large and the elasticity propagating in the concrete Even when the wave energy cannot be received by a sensor element disposed on the concrete, for example, by embedding the sensor element in the receiving range of the elastic wave energy, the propagation speed of the elastic wave can be obtained to perform quality inspection.

  According to the present invention, even if it is an existing concrete structure, or even when the concrete structure is thick, the concrete structure quality inspection can be performed. Moreover, it can test | inspect regardless of the condition of a measurement location. Further, even when the concrete structure is too thick, the inspection can be performed by arranging the sensor elements in the first and second small-diameter holes formed in the elastic wave energy receiving range.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a quality inspection apparatus applied to the concrete structure quality inspection method according to the first embodiment of the present invention. In the present embodiment, “crack” inspection in an existing concrete structure will be described.
In FIG. 1, the quality inspection apparatus 1 for a concrete structure 3 has a defect detection function for measuring “cracking”, and in order to realize this function, a small-diameter hole 5 drilled in an existing concrete structure 3 is provided. Three sensor elements 10A to 10C to be inserted, one oscillation element 11 applied to the surface of the concrete structure 3, oscillation circuit 13, vibration receiving circuit 14, arithmetic circuit 16, and defect detection information display circuit 17 I have. The small-diameter hole 5 is formed on the concrete surface corresponding to the measurement location.

Each of the sensor elements 10A to 10C has the same configuration, and is fixedly locked to a thin reinforcing bar 7 which is a rod-like body at a predetermined interval with a binding band (not shown) as shown in FIG. Although the structure of the sensor elements 10A to 10C will not be described in detail, the main part is piezoelectric ceramics fixed to a metal plate, and the piezoelectric ceramics are housed in a case.
As the rod-shaped body, materials other than various wires and steel materials can be used in addition to the reinforcing bars 7. Further, the rod-like body is not limited to a round shape in cross section, and may be a quadrangle or a triangle.

  The sensor element 10A and the sensor element 10B are used to detect the development of the strength of the filler 3a filled in the small diameter hole 5. The sensor element 10 </ b> C and the oscillation element 11 are used for detecting cracks in the concrete structure 3.

  Piezoelectric ceramics can convert electrical signals into mechanical signals and vice versa, and can be used not only as oscillation elements but also as receiving elements. In the present embodiment, the sensor element 10A is used as an oscillation element, and the sensor elements 10B and 10C are used as vibration receiving elements. By using piezoelectric ceramics for the sensor elements 10A to 10C, the apparatus can be made inexpensive and high-precision inspection can be performed.

As shown in FIG. 3, the sensor elements 10 </ b> A to 10 </ b> C arranged on the reinforcing bar 7 at a predetermined interval are integrally inserted with the reinforcing bar 7 into a small-diameter hole 5 drilled in a measurement location of the existing concrete structure 3. Is done.
The small-diameter hole 5 into which the sensor elements 10A to 10C are inserted is filled with a high-strength filler 3a using an infusion pump 9, as shown in FIG.

It is considered that the filled filler 3a is integrated with the concrete structure 3 when the strength is confirmed. Thereby, when quality inspection of the existing concrete structure 3 is performed, the sensor elements 10A to 10C are arranged in the structure before the concrete is placed and embedded in the structure after the placement, so that the non-concrete structure is removed. It can be handled almost the same as when performing destructive inspection.
In addition, as the filler 3a, it is desirable to use a cement-type super-hard hard non-shrink mortar (for example, Taiheiyo Material Co., Ltd. “Preeurox Super”) whose density is close to that of concrete.

The sensor element 10A and the sensor element 10B are arranged on the reinforcing bar 7 with a predetermined distance L as described above.
Returning to FIG. 1, the vibration signal Sr is applied from the oscillation circuit 13 to the sensor element 10A. The sensor element 10B is used for vibration detection of the elastic wave 30 generated by the vibration of the sensor element 10A and propagating through the filler 3a. The sensor element 10B is generated not only by receiving and detecting the elastic wave 30 generated by the vibration of the sensor element 10A, but also by the vibration of the oscillation element 11 in order to detect “cracking” of the concrete structure 3 described later. It is also used for vibration detection of the elastic wave 30 propagating in the concrete structure 3.

  The oscillation element 11 generates an elastic wave, and when the “crack” of the concrete structure 3 is measured, an oscillation signal Sr is applied from the oscillation circuit 13. The sensor elements 10 </ b> A, 10 </ b> B, and 10 </ b> C detect and receive the elastic wave 30 that is generated by the vibration of the oscillation element 11 and propagates in the concrete structure 3.

  The oscillation circuit 13 generates a sinusoidal electric signal having a constant frequency (for example, 20 kHz to 60 kHz), and outputs an excitation signal Sr for driving the sensor element 10A or the oscillation element 11.

  The vibration receiving circuit 14 receives the elastic wave 30 generated by the vibration of the sensor element 10A and propagating through the filler 3a by the sensor element 10B. The vibration receiving circuit 14 receives the elastic wave 30 generated by the vibration of the oscillation element 11 and propagating through the concrete structure 3 by the sensor element 10C. Further, the sensor elements 10 </ b> A and 10 </ b> B can receive the elastic wave 30 propagating through the concrete structure 3 by the vibration of the oscillation element 11 when the surface of the concrete structure 3 is moved. The vibration receiving circuit 14 inputs the vibration receiving signal Su obtained by the sensor element 10B or the sensor element 10C or the sensor element 10A to the arithmetic circuit 16.

  The arithmetic circuit 16 is composed of a microcomputer or the like, and obtains a phase difference Δt between the vibration signal Sr applied to the sensor element 10A and the vibration receiving signal Su obtained by the vibration receiving circuit 14 receiving the vibration with the sensor element 10B. Then, the acoustic velocity (hereinafter referred to as propagation velocity) V of the elastic wave 30 propagating in the filler 3a is calculated from the obtained phase difference Δt and the separation distance L between the sensor element 10A and the sensor element 10B, and the filling is performed. The strength expression of the material 3a is inspected.

  Further, the arithmetic circuit 16 has a phase difference Δ between the vibration signal Sr applied to the oscillation element 11 and the vibration receiving signal Su obtained by the vibration receiving circuit 14 receiving the vibration at the sensor element 10C, the sensor element 10B, or the sensor element 10A. t is obtained, and the propagation velocity V1 of the elastic wave 30 propagating in the concrete structure 3 is determined from the obtained phase difference Δt and the element 11, 10C, the element 11, 10B, or the separation distance L1 of the element 11, 11A. Calculate and inspect the presence or absence of cracks in the existing concrete structure 3 and detection of defects.

  The information display circuit 17 includes display means such as a liquid crystal display panel (not shown), and from the calculation result of the calculation circuit 16, the condensation of the filler 3a, the development of strength, and the defect determination result of the concrete structure 3 are visibly displayed. indicate.

The arithmetic circuit 16 obtains the phase difference Δt between the vibration signal Sr and the vibration signal Su, and then uses the following equation (1) to propagate the propagation velocity V or the propagation velocity V or the concrete structure 3. V1 is calculated. In this case, since the distance L between the sensor element 10A and the sensor element 10B or the separation distance L1 between the oscillation element 11 and the sensor element 10C is a known value, the propagation velocity V or V1 is easily obtained. be able to.
V (or V1) = L (or L1) / Δt

  When the propagation velocity V reaches the specified value, the strength of the filler 3a is confirmed. That is, the propagation speed V is slow when the strength before curing of the filler 3a is small (at the start), and is fast when the strength at the time of curing is high (at the end). If the speed is high, it can be determined that the process is complete. In this way, the condensation of the filler 3a can be determined.

  In addition, you may test | inspect the expression of the intensity | strength of the filler 3a by the compressive strength test of JISA1108. Or as shown in FIG. 5, it can also confirm using the Schmidt hammer 20 arrange | positioned in the opening position of the small diameter hole 5. FIG.

  After the strength of the filler 3a is increased and a predetermined strength expression is confirmed, the oscillating element 11 is applied to the outer surface of the concrete structure 3 and the elastic wave 30 is applied inside the concrete. As a result, the arithmetic circuit 16 detects the phase difference Δt between the vibration signal Sr applied to the oscillation element 11 and the vibration reception signal Su received by the sensor element 10C and the surface of the concrete structure 3 as described above. The propagation velocity V1 of the elastic wave 30 is calculated based on the distance (depth) to the element 10C, and the presence or absence of “crack” in the concrete is inspected.

That is, the propagation speed in a sound concrete structure 3 is generally around 4000 m / s, but if an air layer is included due to cracks, defects, etc., the propagation speed tends to be reduced to about half, so the propagation speed V1 It is possible to inspect for the presence or absence of a defect or the like by detecting
Note that the propagation velocity V obtained by developing the strength of the filler 3a can be regarded as the propagation velocity of the elastic wave 30 propagating in the concrete structure 3 and used for defect detection. In this case, the distance (depth) from the surface of the concrete structure 3 to the sensor element 10C does not need to be set, and can be set to an arbitrary distance.

  The information display circuit 17 has display means such as a liquid crystal panel, a plurality of LEDs (light emitting diodes), a buzzer, and a notification means, and is estimated from the propagation velocity V or V1 calculated by the arithmetic circuit 16 and the propagation velocity V. The strength of the filler 3a, the presence or absence of defects in the concrete estimated from the propagation velocity V1 is numerically displayed on the liquid crystal panel, or is displayed in stages (levels) using LEDs. When a notification signal is input, a buzzer is sounded or an LED is lit.

  The sensor elements 10A to 10C correspond to the first sensor element. Further, the oscillation element 11 has the same configuration as the sensor elements 10A and 10B, so that electric energy and mechanical energy can be reversibly converted, and replaced with a sensor element that can be used not only as an oscillation element but also as a vibration receiving element. You can also. The sensor element in this case corresponds to the second sensor element.

  In the present embodiment, it has been described that the reinforcing bar 7 to which the sensor elements 10A to 10C are attached is simply inserted into the small diameter hole 5, but preferably, the sensor elements 10A to 10C are located in the center of the hole spaced from the inner wall of the small diameter hole 5. It is preferable that the position of the rod-shaped body that is the reinforcing bar 7 is regulated in the hole so as to be disposed in the hole.

10 and 11 illustrate the position restriction of the rod-shaped body.
In FIG. 10, two rebars 7a and 7b are spaced apart at a slightly narrower interval than the inner diameter of the small-diameter hole 5, and the sensor elements 10A to 10C are attached so as to bridge both the rebars 7a and 7b.
In FIG. 11, one reinforcing bar 7 c is bent into a continuous mountain shape with a width slightly narrower than the inner diameter of the small-diameter hole 5, and each bent portion is brought into contact with the inner wall of the small-diameter hole 5. The position is regulated within the small-diameter hole. Each of the sensor elements 10A to 10C is attached to each central portion of the bent reinforcing bar 7c.

  By restricting the position of the rod-like body in the small-diameter hole 5 in this way, the sensor elements 10A to 10C are arranged at the center of the small-diameter hole 5 to avoid contact with the inner wall. False detection due to contact with an existing concrete structure when detecting the development of strength is prevented. Or the distance (depth) from the surface of the concrete structure 3 to each sensor element 10A-10C is stabilized, and an exact crack detection can be performed.

Next, the concrete structure quality inspection method of the present embodiment will be described with reference to FIG.
In order to carry out the quality inspection method for the existing concrete structure 3, first, the small-diameter hole 5 is drilled in the measurement location of the concrete structure 3, and the reinforcing bar 7 to which the sensor elements 10 </ b> A to 10 </ b> C are attached is inserted into the small-diameter hole 5. Then, the small diameter hole 5 is filled with the filler 3a. At this time, the distance L between the sensor element 10A and the sensor element 10B is set in advance (see FIG. 2). Next, the sensor element 10A and the sensor element 10B oscillate and receive vibration, and the propagation velocity V is measured from the phase difference Δt between the oscillation waveform and the received waveform and the distance L between the sensor elements 10A and 10B.

  When the hardening of the filler 3a is confirmed based on the measured propagation velocity V, the oscillating element 11 is then brought into contact with the outer surface of the concrete so as to face the sensor element 10C. The oscillating element 11 and the sensor element 10C The oscillation speed and the vibration are received, and the propagation velocity V1 is measured from the phase difference Δt between the oscillation waveform and the reception waveform and the distance (depth) L1 between the oscillation element 11 and the sensor element 10C. When the measured propagation velocity V1 is significantly slower than the propagation velocity in a sound concrete structure, it is determined that “crack: C” exists in the concrete.

  In addition, when crack C is detected and repair work is carried out on this crack C, after repairing, the concrete structure inspection method is performed again, and the effect of repair is compared by comparing the propagation speed of elastic waves before and after repair. Can be confirmed.

  As described above, according to the concrete structure quality inspection method of the present embodiment, the sensor elements 10A to 10C are arranged in the small-diameter holes formed in the subsequent process with respect to the existing concrete structure 3, and the crack C is measured. Therefore, even if it is the existing concrete structure 3, the quality inspection of a concrete structure can be performed.

Even if the concrete structure is thick, by embedding the sensor element within the elastic wave energy receiving range, the propagation speed of the elastic wave can be obtained and quality inspection can be performed.
In addition, when performing crack inspection in the prior art, even if it is difficult to apply two ultrasonic probes because there are external walls or upper floors adjacent to the measurement location, If the element 11 can be applied to the outer surface of the concrete structure 3, the quality inspection can be performed without being affected by the shape of the concrete structure.

  In the above embodiment, the three sensor elements 10A to 10C are attached to the reinforcing bar 7 and arranged in the small-diameter hole 5. The strength of the filler 3a is expressed as shown in FIG. 5, for example. If the detection is performed using another method or apparatus, the quality inspection can be performed by placing one sensor element 10C in the concrete.

  In the above embodiment, the acoustic wave oscillated by the oscillating element 11 is received by the sensor element 10C. However, as described above, the vibration of the oscillating element 11 that has moved the surface of the concrete structure 3 is applied. The generated elastic wave 30 may be received by the sensor elements 10A and 10B to determine the propagation velocity. In particular, since the sensor elements 10A to 10C of the present embodiment have no anisotropy, they can oscillate and receive waves evenly in any of the front, rear, left, and right directions. Further, if the sensor elements 10A and 10B are used for detecting cracks without using the sensor element 10C, the product cost can be reduced.

  In the above embodiment, only “cracking” is measured. However, since the propagation speed of the elastic wave is correlated with the compressive strength of the concrete, the diagnosis is performed when the deterioration of the concrete structure 3 is diagnosed. As a reference, the compressive strength can also be estimated. That is, when the compressive strength is small, the propagation speed is small, and when the compressive strength is large, the propagation speed is large. Therefore, it is possible to estimate the “compressive strength of the concrete” from this speed function and perform deterioration diagnosis.

  In the above embodiment, the oscillating element 11 generates an elastic wave. Like the sensor elements 10A to 10C, the oscillating element 11 is a sensor element capable of reversibly converting electrical energy and mechanical energy. Also good.

  In the above embodiment, the acoustic wave propagating in the concrete due to the mechanical vibration generated by the oscillation element 11 is detected by the sensor element 10C. However, instead of the oscillation element 11, electric energy and mechanical energy are reversibly changed. Applying a convertible sensor element (a “second sensor element” in the present specification), for example, an oscillation signal is applied to the sensor element 10A to generate mechanical vibration, and the mechanical vibration causes the inside of concrete. The second sensor element applied to the outer surface of the concrete is detected by detecting the elastic wave propagating through the surface of the concrete to extract the vibration receiving signal, and the phase difference between the extracted vibration receiving signal and the oscillation signal applied to the sensor element 10A is obtained. You can also.

  In the above embodiment, “cracking” is measured from the phase difference between the sensors and the propagation speed. However, when an air layer is generated in the concrete, the phase difference between the oscillation waveform and the receiving waveform is remarkably large. Since it becomes large, it is possible to estimate a crack only by the obtained phase difference.

Next, a concrete structure quality inspection method according to the second embodiment of the present invention will be described with reference to FIG.
In FIG. 7, the same reference numerals are given to the same parts as those in FIG.
The concrete structure quality inspection method according to the present embodiment uses the sensor elements 10A to 10C embedded in an existing concrete structure as oscillation elements (elements that convert electrical energy into mechanical energy), and the concrete structure 3 A plurality of sensor elements 12A, 12B,..., 12N attached to the outer surface of the sensor are used as vibration receiving elements (elements that convert mechanical energy into electrical energy), and the distance between the sensor elements is calculated, The propagation speed of the elastic wave 30 is obtained. Then, it is estimated that defects such as cracks and junka (bean board) are generated at locations where the propagation speed is extremely slow.

  That is, the concrete structure quality inspection method according to the present embodiment generates mechanical vibrations by sequentially applying an oscillation signal to the sensor elements 10A to 10C serving as the oscillation elements, and the oscillation element that generates the mechanical vibrations. From the sensor elements 12A, 12B,..., 12N at the opposing positions, a vibration receiving signal obtained by detecting an elastic wave propagating in the concrete by mechanical vibration of the oscillation elements (10A to 10C) is extracted. The propagation speed of the elastic wave is obtained based on the phase difference between the oscillation signal and the vibration receiving signal of the sensor element 12A and the distance between the sensor elements 10A and 12A.

Thereby, the measurement location of the concrete structure 3 can be test | inspected extensively at once.
In the case where a plurality of measurement locations are inspected simultaneously as in the above-described embodiment, it is not necessary to provide the arithmetic circuit 16 and the information display circuit 17 corresponding to each set of sensor elements. It is made to switch suitably using the switcher of.

  In addition, accurate “cracking” can be obtained by arranging the sensor elements 12A, 12B,..., 12N serving as vibration receiving elements directly above the sensor element 10A, the sensor element 10B, or the sensor element 10C in the concrete. However, even if it is not placed directly above, the “crack” can be accurately obtained by using the Heron formula. In an actual site, the position of the sensor element 10A, the sensor element 10B, or the sensor element 10C in the concrete may not be accurately grasped, and an accurate propagation speed cannot be obtained. Therefore, by using Heron's formula, it is possible to accurately determine the propagation velocity even if the receiving elements (12A, 12B,..., 12N) are not arranged immediately above the sensor element 10A, the sensor element 10B, or the sensor element 10C. it can.

  For example, as shown in FIG. 8, "A" is the position of the sensor element 12A that is the receiving element, "B" is the position of the sensor element 10A that is the oscillation element, and "C" is the position of the sensor element 10B that is the oscillation element. And The distance a between “B” and “C” is the distance between the sensor element 10A and the sensor element 10B and is known. The distance b between “A” and “C” is obtained from the velocity of the elastic wave and the phase difference between the oscillation signal of the oscillation element (10B) and the oscillation signal of the oscillation element (12A). The distance c between “B” is obtained from the velocity of the elastic wave and the phase difference between the oscillation signal of the oscillation element (10A) and the reception signal of the reception element (12A). Accordingly, the area S of a triangle having A, B, and C as vertices from the three distances a, b, and c can be obtained from Heron's formula.

S = (s × (s−a) × (s−b) × (s−c)) ^1/2
However, s = 1/2 × (a + b + c).
Therefore, the accurate separation distance L between the vibration receiving element (12A) to be disposed immediately above the sensor element 10A or the sensor element 10B and the sensor element 10A or the sensor element 10B is as follows.
L = 2S / a
The position where both “L” values are minimum in the two directions (X, Y) is directly above the sensor element 10A or 10B where the vibration receiving element (12A) is to be arranged. In search of cracks.

FIG. 9 is a diagram illustrating a concrete structure quality inspection method according to the third embodiment of the present invention.
In FIG. 9, the same reference numerals are given to the portions common to FIG. 6, and the description thereof is omitted.
In the concrete structure quality inspection method according to this embodiment, the thickness of the concrete structure member is too large, and the elastic wave energy propagating in the concrete cannot be received by, for example, a sensor element applied to the outer surface of the concrete structure. It is suitable for.

  That is, in this quality inspection method, two small-diameter holes 5A and 5B are drilled at positions on the existing concrete structure 3 that are separated by a predetermined interval and within the elastic wave energy receiving range. An oscillation signal is applied to the sensor element 10A embedded in the small-diameter hole 5A to generate mechanical vibration, and an elastic wave propagating through the concrete by the mechanical vibration is detected by the sensor element 12A embedded in the second small-diameter hole 5B. Then, the phase difference Δt between the vibration receiving signal obtained at that time and the oscillation signal applied to the sensor element 10A embedded in the first small-diameter hole 5A is obtained, and the obtained phase difference Δt is separated from the small-diameter holes 5A and 5B. From the distance, the propagation velocity V of the elastic wave is calculated, and the quality inspection of the existing concrete structure 3 is performed.

  Thereby, by drilling the two small diameter holes 5A and 5B corresponding to the measurement location and embedding the oscillation element and the receiving element in the existing concrete structure 3, the member thickness of the concrete structure is too large. However, it is possible to reliably perform quality inspection by obtaining the propagation speed of the elastic wave.

It is a block diagram which shows the structure of the concrete structure quality inspection apparatus applied to the 1st Embodiment of this invention. It is a figure which shows the structure of the sensor element attached to the reinforcing bar. It is a figure which shows the small diameter hole for sensor embedding. It is a figure which shows a mode that a filler is filled. It is a figure explaining the intensity inspection of a filler. It is a figure explaining the concrete structure quality inspection method which concerns on the 1st Embodiment of this invention. It is a figure explaining the concrete structure quality inspection method which concerns on the 2nd Embodiment of this invention. It is a figure explaining the method of calculating | requiring the separation distance between sensors by Heron's formula. It is a figure explaining the concrete structure quality inspection method which concerns on the 3rd Embodiment of this invention. It is a figure explaining the example of a change of the rod-shaped object applied to each embodiment of this invention. It is a figure explaining the other example of a change of the rod-shaped object applied to each embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concrete structure quality inspection apparatus 5 Small diameter hole 5A 1st small diameter hole 5B 2nd small diameter hole 7 Reinforcing bar 10A, 10B, 10C Sensor element 11 Oscillation element 12A, 12B, ..., 12N Vibration receiving element 13 Oscillation circuit 14 Vibration receiving Circuit 16 Arithmetic circuit 17 Information display circuit 30 Elastic wave

Claims (5)

Preparing a rod-like body to which a first sensor element capable of reversibly converting electrical energy and mechanical energy is attached;
Forming a small-diameter hole in an existing concrete structure;
Inserting the rod-like body having the sensor element attached to the small-diameter hole, and then filling the small-diameter hole with a filler to embed the sensor element in concrete. How to attach to the structure.   A plurality of the first sensor elements are arranged apart from the rod-shaped body, an oscillation signal having a constant frequency is applied to one sensor element to generate mechanical vibration, and the mechanical vibration is propagated in the concrete. The elastic wave is detected by another sensor element, the phase difference between the vibration receiving signal obtained at that time and the oscillation signal applied to the one sensor element is obtained, and from the obtained phase difference and the separation distance between the sensor elements, The method for attaching a sensor element to a concrete structure according to claim 1, wherein an elastic velocity of the elastic wave is calculated to check the expression of strength of the filler. Including a step of restricting the position of the rod-shaped body by bringing at least a part of the rod-shaped body into contact with the inner wall of the small-diameter hole,
2. The method for attaching a sensor element to a concrete structure according to claim 1, wherein the first sensor element is disposed apart from an inner wall of the small-diameter hole.   The second sensor element capable of reversibly converting electric energy and mechanical energy, or an oscillation element or elastic element capable of generating an elastic wave while performing the method of attaching the sensor element according to claim 1 to a concrete structure. An oscillation signal is applied to either the second sensor element, the oscillation element or the first sensor element in a state where a receiving element capable of receiving a wave is applied to the outer surface of the concrete structure. The elastic wave that is generated and propagates in the concrete by the mechanical vibration is detected by the first sensor element, the second sensor element or the vibration receiving element, and the vibration receiving signal and the second sensor obtained at that time are detected. The phase difference with the oscillation signal applied to the element or the oscillation element or the first sensor element was obtained, and the obtained phase difference was applied to the outer surface of the concrete structure. A quality inspection is performed by calculating an elastic velocity of the elastic wave from a distance between the second sensor element or the oscillation element or the receiving element and the first sensor element disposed in the concrete structure. Concrete structure quality inspection method characterized by the above.   The method for attaching the sensor element to a concrete structure according to any one of claims 1 to 3 is applied to each of at least two small-diameter holes formed at positions on the concrete structure that are spaced apart by a predetermined distance. An oscillation signal is applied to the sensor element embedded in the surface to generate mechanical vibration, and the elastic wave propagating in the concrete due to the mechanical vibration is detected by the sensor element embedded in the second small-diameter hole, and obtained at that time. The phase difference between the received vibration signal and the oscillation signal applied to the sensor element embedded in the first small-diameter hole is obtained, and the propagation speed of the elastic wave is calculated from the obtained phase difference and the separation distance between the small-diameter holes. A quality inspection method for a concrete structure, characterized by performing quality inspection.

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