JP2002131294A - Nondestructive compression test method and device for concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a highly reliable rest result without damaging structure due to member loss. SOLUTION: A strike point P, on an extension line for connecting detection points Q1 and Q2 on a concrete surface 20, is struck to generate elastic waves; vibration is detected at the detection points Q1 and Q2; and at the same time, the detection time difference T is calculated and detected, speed V of the elastic wave is calculated, based on the time difference T and an interval L between the detection points Q1 and Q2, and compression speed fc of concrete is calculated and outputted based on the speed V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nondestructive compression test method for concrete, which is suitable for testing the compressive strength of concrete formed articles (for example, existing concrete structures, concrete products such as piles and fume pipes, etc.). And a non-destructive compression test apparatus.

[0002]

2. Description of the Related Art There are the following methods for testing the compressive strength of a concrete structure. A test piece is prepared at the time of placing concrete, and a compression test is performed on the test piece at a predetermined time by a compression tester. A part of a place to be examined, such as a pillar, a beam, a wall, etc., is sampled by core boring or the like, and the sampled sample is tested by a compression tester. Perform a non-destructive compression test by the surface hardness method (Schmidt hammer).

[0003]

However, the above,
The method has the following disadvantages. In the case of (1), there are inconveniences such as complicated management of preparation, curing, storage, etc. of the test piece, and incompatibility of inferring the strength of the actual structure indirectly from the strength of the test piece. In the case of: A part of the structural body is sampled, which causes a defect, and this sampling requires a large-scale operation. In the case of: Since the test is carried out by hitting concrete locally, it is susceptible to variations in surface hardness, resulting in relatively large variations in test results and lacking reliability.

[0004] In view of the above circumstances, the present invention can provide a reliable test result without problems of management complexity and compatibility, no damage to the structure due to a missing member, and the like. It is an object of the present invention to provide a non-destructive compression test method and a non-destructive compression test device for concrete.

[0005]

Means for Solving the Problems According to the present invention for solving the above-mentioned problems, a first aspect of the present invention is a method for detecting a plurality of sensors disposed on a surface (20) of a concrete (40) to be subjected to a nondestructive compression test. On the extension line connecting the points (Q1, Q2), the concrete surface is vibrated by hitting the surface of the concrete, and the vibrations generated in the concrete are detected at the plurality of detection points, and the vibrations are detected at the detection points. Is detected, a propagation speed (V) of the vibration is calculated based on the detected time difference and an interval (L) between the plurality of detection points, and based on the propagation speed. Calculating and outputting the compressive strength (fc) of the concrete;
A non-destructive compression test method for concrete, characterized in that:

According to a second aspect of the present invention, in the non-destructive compression test method, there is provided a detecting portion (3t) which can be arranged on the surface of the concrete, and the vibration of the concrete is detected via the detecting portion. A plurality of flexible vibration detecting means (3) are provided on the frame (2) in such a manner that the detecting portions are arranged at predetermined intervals (L). , The detection units of the plurality of vibration detection units are respectively arranged at the plurality of detection points, and the detection is performed by these vibration detection units.

According to a third aspect of the present invention, there is provided a non-destructive compression test apparatus (1) used for performing a non-destructive compression test on concrete by the non-destructive compression test method, comprising a frame (2), A plurality of vibration detecting means (3) are provided on the frame, and the vibration detecting means has a detecting part (3t) which can be arranged at a detecting point on the surface of the concrete, and detects vibration via the detecting part. A detection result output unit (7) for outputting a detection result is provided, and the detection units of the vibration detection units are arranged at a predetermined arrangement interval (L) between the plurality of vibration detection units. I do.

According to a fourth aspect of the present invention, in the non-destructive compression test apparatus, a time difference detecting section (14) for detecting a time difference (T) when vibrations are detected by the plurality of vibration detecting means based on the detection result. A propagation speed calculator (12) for calculating a propagation speed (V) of the vibration based on the detected time difference and the arrangement interval; and calculating a compressive strength (fc) of the concrete based on the propagation speed. And a compression strength calculation output section (13, 15, 16) for outputting.

According to a fifth aspect of the present invention, in the non-destructive compression test apparatus, the frame is provided with a handle portion (2a) for carrying.

Note that the numbers in parentheses are for convenience of indicating corresponding elements in the drawings, and therefore, the present description is not limited to the descriptions on the drawings.

[0011]

As described above, according to the first aspect of the present invention, since the test piece is not used, there is no complicated management and no problem of compatibility. Further, since a part of the concrete skeleton to be tested is not collected, the structural skeleton is not damaged, and a large-scale operation is not required. In addition, since the propagation speed of the vibration between the two detection points is obtained, it is hardly affected by the variation in the surface hardness of the concrete, and the test results do not vary.
High reliability. Further, since it is only necessary to hit at an arbitrary point near the extension line connecting the two detection points, the test can be easily performed, which is convenient.

According to the second aspect of the present invention, vibration can be conveniently detected at a plurality of detection points arranged at predetermined intervals only by arranging the frame on concrete.

According to the third aspect of the present invention, by using the non-destructive compression test apparatus of the present invention, the vibration at a plurality of detection points arranged at predetermined intervals can be obtained simply by disposing the frame on concrete. This is convenient because it can detect the

According to the fourth aspect of the present invention, it is convenient to output the compressive strength of concrete only by installing the non-destructive compression test apparatus of the present invention.

According to the fifth aspect of the present invention, it is convenient because the carrying of the frame and the arrangement with respect to the concrete are simplified.

[0016]

FIG. 1 is a schematic view showing a state in which a nondestructive compression test of concrete is performed by a nondestructive compression test apparatus. The non-destructive compression test apparatus 1 includes an instrument 4 and a control device 10, as shown in FIG. The device 4 has a rod-shaped frame 2, which is made of a material having a lower elastic wave velocity than concrete so as not to affect the test results.

Vibrometers 3 are provided in the vicinity of both ends of the frame 2, respectively, and a gap is formed between the vibrometers 3 to form a U-shape as a whole. In the vicinity of the center of the frame 2, a handle 2a that can be gripped and carried by a tester by hand is formed. The vibration meter 3,
An interface unit 7 such as a connector electrically connected to 3 is provided, and a cable 5 is detachably connected to the interface unit 7. The side of the cable 5 opposite to the device 4 is connected to the control device 10.

FIG. 2 is a block diagram showing a control configuration of the nondestructive compression test apparatus. Each vibrometer 3 has a horizontal sensor 3b, as shown in FIG. 2, and a cable 5 is connected to the horizontal sensor 3b via an interface unit 7, which is omitted in FIG. As shown in FIG. 1, each vibration meter 3 has a detection unit 3 for detecting vibration by a horizontal sensor 3 b.
t (probe etc.) is provided, and two vibrometers 3,
The interval between the three detectors 3t, 3t is a predetermined interval L.

As shown in FIG. 2, a main controller 11 is provided on the controller 10 side. The main controller 11 is connected to the main controller 11 via a filter / amplifier 6 and an A / D converter (not shown). The cable 5 described above is connected. The vibration is captured by the above-described horizontal sensor 3b, and the detection signal S1 or S2
Is transmitted via the cable 5, and the vibration in the target frequency band is extracted and amplified by the filter / amplifier 6. Further, the main control unit 11 is provided with a time difference detection unit 14, a speed calculation unit 12, a compression strength calculation unit 13, a display output unit 15, a recording unit 16, and the like via an internal bus. Although the device 4 and the control device 10 are separate types in FIG. 1, the function of the control device 10 may be built in the frame 2 or the like of the device 4 to provide portability and portability.

FIG. 3 is a schematic sectional view showing an example of the compression wave generator. The compression wave generator 30 used when performing a non-destructive compression test described below using the non-destructive compression test apparatus 1 described above is installed on a concrete surface 20 that forms a flat slab or the like, for example, as shown in FIG. Free frame 3
A cylinder 32 disposed horizontally (parallel to the concrete surface 20) is fixed to the frame 31. A piston-shaped weight 33 that can reciprocate in the cylinder 32 is provided in the cylinder 32, and a spring 35 is provided on one of the weights 33.

In order to use the compressional wave generator 30, first, as shown by the solid line in FIG. 3, the weight 33 is placed at the first position PS1 by compressing the spring 35. This first
The weight 33 is fixed to the cylinder 32 via the pin 36 at the position PS1. When the compression wave is generated in the concrete, the pin 36 is pulled out. As a result, the compression of the spring 35 is released, and the weight 33 moves violently in the cylinder 32 to the second position PS2 (indicated by a two-dot chain line) and hits the wall 32a of the cylinder 32. The impact hitting the wall 32a is transmitted to the concrete 40 via the frame 31, and a compression wave (elastic wave) is generated near the concrete surface 20.

Since the non-destructive compression test apparatus 1 and the like are configured as described above, the non-destructive compression test of concrete is performed using the non-destructive compression test apparatus 1 as follows.
First, as shown in FIG.
(Frame 2) is placed on concrete 40 to be tested (in the figure, an example of a horizontal concrete slab is shown). At the time of installation, the detectors 3t, 3t of the two vibrometers 3, 3 are arranged so as to contact the concrete surface 20. The points at which the detecting portions 3t abut on the concrete surface 20 are referred to as detecting points Q1 and Q2, respectively.

Next, at the point P (FIG. 1) near the extension line connecting the two detectors 3t, 3t, the compression wave generator 30
Is installed. As a result, the detection points Q1 and Q2 and the point P are arranged in series. After installation, the compression wave generator 3
At 0, a compression wave (elastic wave) is generated in the concrete 40 by the procedure already described. In the case where the concrete to be tested is a member whose side surface is exposed, such as a beam or a column, the same compression wave is generated by hitting the side surface with a hammer or the like without using the compression wave generator 30. be able to. Further, the compression wave generator 30 shown in the present embodiment is used.
Is merely an example, and the compression wave may be generated by another device or method.

Each of the vibrometers 3 of the non-destructive compression test apparatus 1 detects the above-mentioned elastic waves with a time difference corresponding to the interval L via the detecting section 3t. Detection signals S1 from vibration meters 3 and 3
S2 is sequentially transmitted to the control device 10 via the cable 5 via the interface unit 7. In the control device 10, the detection signals S1 and S2 are converted to A by an A / D converter (not shown).
The time difference detector 14 calculates the rise time difference T between the A / D converted detection signals S1 and S2 and transmits the calculated time difference T to the speed calculator 12. Various other methods can be used to detect the time difference T. For example, the timer may be started when the first detection signal is received, the timer may be stopped when the next detection signal is received, and the time measured by the timer may be detected as the time difference.

The speed calculating section 12 calculates the speed V of the elastic wave generated in the concrete based on the transmitted time difference T. That is, since the time difference T is equal to the time required for the elastic wave to move through the interval L between the detection units 3t, 3t, the interval L is divided by the time difference T to determine the velocity V of the elastic wave. The speed calculator 12 transmits the calculated speed V to the compression strength calculator 13.

FIG. 5 is a diagram showing waveform data detected by each vibrometer. For example, when the interval L is 30 cm,
The waveform data of the two vibrometers 3 and 3 is as shown in DAT1. The vibrometers 3 detect the rising points A and A 'of the waveform of FIG. 5, respectively. DAT2 and DAT3 are
In this example, the intervals L are 50 cm and 100 cm, respectively. In DAT2, the vibrometers 3 and 3 detect the rising points B and B 'of the waveform, respectively.
No. 3 detects the rising points C and C 'of the waveform, respectively.

FIG. 4 is a diagram showing the relationship between the elastic wave velocity and the compressive strength of concrete. The compression strength calculation unit 13 calculates the compression strength by substituting the velocity V of the transmitted elastic wave into a relational expression between the elastic wave velocity and the compression strength statistically obtained from an experiment. Generally, for each type of concrete,
The relationship between the strength (N / mm ² ) of the concrete and the elastic wave velocity (m / s) propagating through the concrete is determined. For example, for the concrete to be tested in the present embodiment, as shown in FIG. 4, an experimental statistical formula of concrete strength fc and elastic wave velocity; fc = Φ (V) is previously obtained based on experiments, and the compressive strength calculating unit 13 Is the experimental statistical formula;
fc = Φ (V) is held. Therefore, the compressive strength calculator 13 obtains the compressive strength fc of the concrete by substituting the speed V into the experimental statistical formula; fc = Φ (V).

The compression strength f calculated by the compression strength calculator 13
c is transmitted to the display output unit 15, and the display output unit 15 displays the compression strength fc via a display (not shown). Further, the compression strength fc is transmitted to the recording unit 16, and recording is performed by a magnetic disk, a printer, or the like controlled by the recording unit 16.

As described above, in the present embodiment, since no test piece is used, there is no management complexity and no problem of compatibility. In addition, since a part of the structural body to be tested is not collected, the structural body is not damaged, and a large-scale operation is not required. Also, two vibrometers 3, 3
Since the velocity of the elastic wave in the concrete over the interval is obtained, it is hardly affected by the variation in the surface hardness of the concrete, and the test results do not vary and the reliability is high.

Further, since it is only necessary to strike at an arbitrary point P in the vicinity of the extension line connecting the two vibrometers 3 and 3, the test can be performed easily and conveniently.

In the above-described embodiment, the test is performed by using the vibration generated in the concrete as the vibration caused by the compression wave (elastic wave). However, the test can be performed by using the vibration as the shear elastic wave. In this case, as shown in FIG. 2, the vibrometer 3 is provided with a vertical sensor 3a. In addition, the compressive strength calculation unit 13 stores an experimental statistical formula relating to shear elastic waves.

That is, the instrument 4 is installed as shown in FIG.
A point P near an extension line connecting the two detection units 3t, 3t is hit almost vertically to the concrete surface 20 by a hammer or the like. This causes vibration in the concrete due to shear elastic waves. Thereafter, similarly to the procedure described above, the detection signals S1 and S2 from the vibrometers 3 and 3 are sequentially transmitted to the control device 10, and the time difference T is detected by the time difference detection unit 14 based on the detection signals S1 and S2. , Speed calculation unit 1
2, the velocity V of the shear elastic wave is calculated based on the time difference T, and the compressive strength calculating unit 13 calculates the velocity V of the shear elastic wave.
Is substituted into the relational expression between the shear elastic wave velocity and the compressive strength statistically obtained from the experiment to calculate the compressive strength, and the calculated compressive strength is displayed on the display via the display output unit 15,
Alternatively, the compression strength is recorded by a magnetic disk, a printer, or the like via the recording unit 16.

The relationship between the elastic modulus and the shear elastic modulus
G = E / {2 (1 + ν)} holds. Meanwhile, elastic
Wave velocity and shear elastic wave velocity are calculated based on elastic modulus and unit volume
Depending on the quantity, the elastic wave velocity Ve = (E / ρ)^1/2, Shear
Elastic wave velocity Vs = (G / ρ) ^1/2There is a relationship. Yo
And G = (Vs / Ve)²・ It becomes E. According to these equations
Calculation of reciprocal elastic wave velocity and shear elastic wave velocity
Is possible. Therefore, the compression strength calculation unit 13
Retain experimental statistical formulas for cleat strength and elastic wave velocity
Thus, the compressive strength calculating unit 13 calculates the experimental statistical formula
And the shear elastic wave velocity,
The contraction strength may be calculated. Conversely, the compression strength
Of the concrete strength and shear elastic wave velocity
Holding the experimental statistical formula, the compression strength calculation unit 13
This experimental statistical formula, the above conversion formula, and the elastic wave velocity
And calculate the compressive strength of concrete.
No.

Each of the vibrometers 3 may have both the sensors 3a and 3b in addition to the configuration having only one of the horizontal sensor 3b and the vertical sensor 3a. Providing both the horizontal sensor 3b and the vertical sensor 3a is convenient because an elastic wave or a shear elastic wave can be selectively adopted according to a test situation.

Each vibrometer 3 has only one sensor,
The direction of the sensor may be freely rotatable. For example, when elastic waves are used, the sensor is rotated and set in the same detection direction as the above-described horizontal sensor 3b for use. When a shear elastic wave is employed, the sensor is rotated and set in the same detection direction as the above-described vertical sensor 3a. By making the orientation of the sensor freely rotatable in this way, the same effect as in the case where both the horizontal sensor 3b and the vertical sensor 3a are provided is obtained, and the vibrometer can be formed simply and compactly by using both sensors.

When employing the above-mentioned rotary sensor,
If the rotation of the sensor is taken into the control device 10 by using an electric contact, it is possible to automatically check the vibration direction and apply the relational expression.

Further, since it is only necessary to be able to measure the propagation speed of the vibration (elastic wave or shear elastic wave) propagating in the space L in the concrete, for example, by hitting one vibrometer directly on the concrete surface 20, the same as in the above-described embodiment can be obtained. Can be obtained.

FIG. 6 is a view showing a state in which a non-destructive compression test apparatus is installed on concrete on which a finishing material is installed.
As shown in FIG. 6, as a test method when the finishing material 25 such as mortar is provided on the concrete surface 20, a hole 26 having a diameter of, for example, about 1 cm is formed through the finishing material 25, and a sensor 3 a with a probe 27 is used. By contacting the concrete surface 20 through the holes 26, damage to the finishing material 25 can be minimized.

In the nondestructive compression test, two vibrometers are provided. If the number of vibrometers is two or more, three
Any number such as four may be used. Even in the case of three or more, the vibrometers may be arranged in series at known intervals.

In the above-described non-destructive compression test, the non-destructive compression device 1 having the above configuration was used. However, without using the non-destructive compression device 1, two (or three or more) sensors were placed at a predetermined interval. And a similar test can be performed.

If the compressive strength of each part of the structure, such as columns, beams, walls, floors, etc., is measured at the time of construction or at a certain time and recorded, it can be changed over time due to aging, fire, earthquake or malfunction. This is convenient because the degree of deterioration can be determined.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state where a non-destructive compression test of concrete is performed by a non-destructive compression test apparatus.

FIG. 2 is a block diagram showing a control configuration of the nondestructive compression test apparatus.

FIG. 3 is a schematic sectional view showing an example of a compression wave generator.

FIG. 4 is a diagram showing a relationship between elastic wave velocity and compressive strength of concrete.

FIG. 5 is a diagram showing waveform data detected by each vibrometer.

FIG. 6 is a view showing a state in which a non-destructive compression test apparatus is installed on concrete on which a finishing material is installed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-destructive compression test apparatus 2 Frame 2a Handle part 3 Vibration detecting means (vibrometer) 3t Detecting part 7 Detection result output part (interface part) 12 Propagation speed calculation part (speed calculation part) 13 Compression strength calculation output part (compression strength) Calculation section) 14 Time difference detection section 15 Compressive strength calculation output section (display output section) 16 Compressive strength calculation output section (recording section) 20 Surface (concrete surface) 40 Concrete fc Compressive strength L interval, arrangement interval (interval) P point Q1 , Q2 Detection point T Time difference V Propagation velocity (velocity)

Claims (5)

[Claims] The method includes: hitting the surface of a concrete on an extension line connecting a plurality of detection points arranged on the surface of the concrete to be subjected to a non-destructive compression test to generate vibrations in the concrete; Detecting the vibration generated in the concrete at the detection point, detecting the time difference at which the vibration was detected at the detection point, and based on the detected time difference and the interval between the plurality of detection points, the propagation speed of the vibration And calculating and outputting the compressive strength of the concrete based on the propagation speed. 2. A plurality of vibration detecting means having a detecting portion which can be freely arranged on the surface of the concrete and which can detect the vibration of the concrete via the detecting portion, wherein the detecting portions are arranged at predetermined intervals. The vibrations generated in the concrete are arranged on the concrete, and the detection units of the plurality of vibration detection units are arranged at the plurality of detection points by arranging the frame on the concrete. 2. The nondestructive compression test method for concrete according to claim 1, wherein the vibration is detected by these vibration detecting means. 3. A non-destructive compression test apparatus used for performing a non-destructive compression test on concrete according to the non-destructive compression test method according to claim 1, further comprising a frame, wherein the frame is provided with a plurality of vibration detecting means. The vibration detecting means includes a detection unit that can be freely arranged at a detection point on the surface of the concrete, and includes a detection result output unit that detects a vibration via the detection unit and outputs a detection result; A non-destructive compression test apparatus, wherein the detection units of the vibration detection units are arranged at predetermined intervals between the detection units. 4. A time difference detecting section for detecting a time difference between the detection of vibrations by the plurality of vibration detecting means based on the detection result, and calculating a propagation speed of the vibration based on the detected time difference and the arrangement interval. The non-destructive compression test apparatus according to claim 3, further comprising: a propagation speed calculation unit; and a compression strength calculation output unit that calculates and outputs a compressive strength of the concrete based on the propagation speed. 5. The non-destructive compression test apparatus according to claim 3, wherein a handle portion for carrying is formed on said frame.