JP2010271207A - Diagnosis method of portion receiving compressive stress in concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine a range of compression failure, a lowering range of compression strength, and a lowering degree of the compression strength in a portion receiving compression stress of a concrete structure. <P>SOLUTION: In this method, an oscillator and a receiver are arranged at a prescribed oscillator-receiver interval on a sound part to measure ultrasonic wave velocity at the sound part by utilizing an ultrasonic wave method, and similar measurement is performed successively by moving a measuring position at a prescribed interval from a position where the compression stress is concentrated toward the sound part, and a velocity ratio at each measuring position acquired by dividing the ultrasonic wave velocity at each measuring position by the ultrasonic wave velocity at the sound part is determined, and the range and the degree of collapse of concrete are determined from the lowering degree of the velocity ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for diagnosing a portion subjected to compressive stress in a concrete structure, and particularly in a concrete structure suitable for determining the range and degree of concrete crushing sites that cannot be grasped by visual observation. The present invention relates to a method for diagnosing a portion subjected to compressive stress.

  When existing concrete structures such as buildings, tunnels, bridges, various waterways, and dams are subjected to external forces such as earthquakes, and the concrete strength deteriorates, it is necessary to repair and reinforce the concrete. There is a need to. In order to measure the strength of a concrete structure, it is necessary to actually measure the concrete structure. As a measuring method, the diameter of the concrete structure is usually 100 mm and the height is a diameter from the surface of the concrete structure to be measured. A cylindrical concrete core having a length of about 200 mm, which is twice as long as the test piece, is subjected to a loading test (compressive strength test) in which a pressure plate is brought into close contact with the upper and lower end surfaces of this test body and compressed by applying a load It has been known. From the result of this loading test, for example, a concrete stress-strain curve as shown in FIG. 4 can be obtained, and the compressive strength of the concrete can be obtained. This type of measurement method is described in Patent Document 1, for example.

Japanese Patent No. 2655529

  By the way, the stress-strain curve of concrete as shown in FIG. 4 obtained from the result of such a loading test is before reaching the maximum compressive strength (test body A) and after reaching the maximum compressive strength (test body B). However, the surface of the specimen B, which is about 80% of the maximum compressive strength after the peak compressive strength, is compared with the surface of the specimen A before the peak compressive strength is observed. However, it is difficult to predict the stress / strain history experienced by the concrete because neither can grasp the range or degree of the collapsed portion.

  Also, in this connection, for example, when a concrete structure such as a box culvert was subjected to an earthquake, a load test of the concrete structure of the box culvert model was performed. In the place where the force was received, it was difficult to determine the crushing place as described above. As shown in FIG. 5, when a box culvert model concrete structure is pressed (in the direction of the arrow shown in FIG. 5), the damaged portion of the concrete structure is divided into a portion subjected to compressive stress and a portion subjected to tensile stress. The portion surrounded by the square is a portion that receives a compressive force, and the opposite side is a portion that receives a tensile force. From the results of this loading test, it is known that the concrete crushing location has reached a concrete strain of 5000μ and the concrete is crushing. If it appears, it can be confirmed by visual inspection, but especially in places subjected to compressive force, there is no crack on the surface, or even if it has occurred, it cannot be confirmed by visual inspection. The range in which the compression strength is reduced, the range in which the compression strength is reduced, and the degree of reduction in the compression strength cannot be determined.

  Therefore, the inventors of the present invention have an object to determine the extent and extent of compressive fracture in a concrete structure that receives compressive stress and cannot visually recognize the state of damage under the surface of the concrete. As a result of intensive research, the ultrasonic method is used to grasp the state of damage under the concrete surface, and the extent of compressive fracture of the concrete, the range where the compressive strength has decreased, and the degree of decrease in the compressive strength are determined. As a result, the present invention has been invented.

In order to achieve the above object, a method for diagnosing a portion subjected to compressive stress in a concrete structure of the present invention is as follows.
(1) An oscillator and a receiver by an ultrasonic method are arranged at a predetermined distance between the oscillator and the receiver in a sound part that is not subjected to compressive stress in a concrete structure, and an ultrasonic pulse is oscillated by the oscillator. By receiving the ultrasonic pulse by the oscillator, the ultrasonic velocity between the oscillator and the oscillator is measured,
(2) The same measurement as the above (1) is sequentially performed by moving the measurement position at a predetermined interval from the position where the compressive stress on the concrete surface is concentrated toward the sound part, and the oscillators at the respective measurement positions and Measure the ultrasonic velocity between the transducers,
(3) Dividing the ultrasonic velocity of each measurement position obtained by (2) above by the ultrasonic velocity of the sound part obtained by (1) above, obtaining the velocity ratio of each measurement position;
(4) The range and degree of concrete crushing are determined based on the degree of decrease in the speed ratio at each measurement position obtained in (3) above.
This is the gist.

In addition, the diagnostic method of the part subjected to compressive stress in the concrete structure of the present invention,
(1) An oscillator and a receiver by an ultrasonic method are arranged at a predetermined distance between the oscillator and the receiver in a sound part that is not subjected to compressive stress in a concrete structure, and an ultrasonic pulse is oscillated by the oscillator. By receiving the ultrasonic pulse by the receiver, the ultrasonic velocity between the oscillator and the receiver and the amplitude of the received ultrasonic wave are measured,
(2) The same measurement as the above (1) is sequentially performed by moving the measurement position at a predetermined interval from the position where the compressive stress on the concrete surface is concentrated toward the sound part, and the oscillators at the respective measurement positions and Measure the ultrasonic velocity between the transducers and the amplitude of the received ultrasonic waves,
(3) The ultrasonic velocity and amplitude of each measurement position obtained in (2) above are divided by the ultrasonic velocity and amplitude of the healthy part obtained in (1), respectively. Find the speed ratio and amplitude ratio of
(4) The range and degree of concrete crushing are determined based on the degree of decrease in the speed ratio and amplitude ratio at each measurement position obtained in (3) above.
This is the gist.

  According to the method for diagnosing a part subjected to compressive stress in a concrete structure of the present invention, the ultrasonic velocity is used to measure the ultrasonic velocity at each healthy position and each measurement position, and the ultrasonic velocity at each measurement position is determined. Obtain the speed ratio of each measurement position obtained by dividing by the ultrasonic speed of the healthy part, and determine the range and degree of concrete crushing according to the degree of decrease in this speed ratio, so about the part that received compressive stress, There is an extraordinary effect that the range of compressive fracture of concrete, the range of reduced compressive strength, and the degree of reduced compressive strength can be determined.

  In addition, according to the diagnostic method of a portion subjected to compressive stress in the concrete structure of the present invention, the ultrasonic method is used to measure the sound speed, the ultrasonic velocity and the ultrasonic amplitude of each measurement position, The speed ratio and amplitude ratio of each measurement position obtained by dividing the ultrasonic speed and amplitude of the measurement position by the ultrasonic speed and amplitude of the healthy part are obtained, and the concrete is calculated according to the degree of decrease in the speed ratio and amplitude ratio. Since the range and degree of crushing are determined, it is possible to determine the range of compressive fracture of concrete, the range of decrease in compressive strength, and the degree of decrease in compressive strength for the part subjected to compressive stress. There is an effect.

The flowchart which shows the diagnostic method of the site | part which received the compressive stress in the concrete structure in one embodiment of this invention The perspective view which shows the measuring method of the arrangement state and ultrasonic velocity of an oscillator and a receiver in the site | part which received the compressive stress of the concrete structure in the same diagnostic method The figure which shows the relationship between the height position of the part (partition) which received the compressive stress of the concrete structure, and the speed ratio in the same diagnostic method Diagram showing stress-strain curve of concrete obtained by conventional loading test The figure which shows the diagnostic result obtained from the loading test of the concrete structure of the box culvert model

  Next, embodiments for carrying out the present invention will be described with reference to the drawings. In this embodiment, a method for diagnosing a portion of the box culvert model concrete structure shown in FIG. This diagnostic method determines the range and extent of concrete crushing by performing each step using the ultrasonic method shown in FIG.

  First, an oscillator and a receiver are arranged at a predetermined distance between the oscillator and the receiver in a sound portion of the concrete structure that is not subjected to compressive stress. In this case, the resonator and the resonator are arranged on the wall surface of the middle portion in the vertical direction of the partition wall so that the distance between the resonator and the resonator is about 600 mm, for example. Then, an ultrasonic pulse is oscillated by the oscillator, and the ultrasonic pulse is received by the receiver. From the propagation time of the ultrasonic wave between the oscillator and the receiver, the ultrasonic wave between the oscillator and the receiver is detected. The sound velocity is measured, and the amplitude of the received ultrasonic wave is also measured. In this way, ultrasonic velocity data and amplitude data in the healthy part of the partition are obtained (step 1).

  Next, the same measurement as step 1 is sequentially performed by moving the measurement position at a predetermined interval from the position where the compressive stress on the concrete surface is concentrated toward the healthy part. In this case, the haunch part below the partition wall is a place where compressive stress is concentrated. Therefore, as shown in FIG. 2, first, the resonator 1 and the resonator 2 are arranged in the hunched portion C <b> 1 at a predetermined resonator-resonator distance (for example, 600 mm), and between the resonator 1 and the resonator 2. The ultrasonic velocity is measured, and the amplitude of the received ultrasonic wave is also measured. Subsequently, the measurement positions are moved upward from the haunch portion C1 and downwardly in the opposite direction, and the measurement positions are moved at predetermined intervals, in this case, for example, at intervals of 50 mm, and the same measurement is sequentially performed at each measurement position. Then, the ultrasonic velocity between the oscillator 1 and the vibrator 2 at each measurement position and the amplitude of the received ultrasonic wave are measured. In general, it is known that fine cracks begin to occur near the peak of compressive strength, and cracks increase after passing the peak. Will drop. In this way, ultrasonic velocity data and amplitude data are obtained at the site of the partition wall subjected to the compressive stress (step 2).

  Next, the ultrasonic velocity and amplitude of each measurement position obtained in step 2 are respectively divided by the ultrasonic velocity and amplitude of the healthy part obtained in step 1, and the velocity ratio and amplitude ratio of each measurement position are obtained. Obtain (step 3).

  Then, the range and degree of concrete crushing are determined based on the degree of decrease in the speed ratio and amplitude ratio at each measurement position obtained in step 3 (step 4). FIG. 3 shows the relationship between the height position of the partition wall and the speed ratio. The legend is an interlayer deformation angle representing the inclination of the partition wall. As is apparent from FIG. 3, when the interlayer deformation angle is 26/1000, the speed ratio of the haunch part decreases to 75%, and the range is about 100 mm above the haunch part and 50 mm below the haunch part. It can be seen that the level has been reached. When the interlayer deformation angle is 0/1000, the speed ratio is 100% including the haunch portion, and it can be seen that the compressive stress concentrated on the haunch portion increases as the interlayer deformation angle increases. In addition, when the strain of the concrete in this portion was measured, the strain of the concrete in this portion reached about 4000 μm, which was a post peak.

  As described above, according to the method for diagnosing a portion of a concrete structure that has been subjected to compressive stress, an ultrasonic method is used to place an oscillator and a vibrator on a predetermined part of the concrete structure. Arrange the distance between the pendulums, measure the ultrasonic velocity between the oscillator and the pendulum, and the amplitude of the received ultrasonic wave, and perform the same measurement from the position where the compressive stress on the concrete surface is concentrated. The measurement position is moved toward the part at predetermined intervals and sequentially performed, and the ultrasonic velocity between the oscillator and the vibrator at each measurement position and the amplitude of the received ultrasonic wave are measured, and the superposition of each measurement position is measured. The velocity ratio and amplitude ratio of each measurement position obtained by dividing the sonic velocity and amplitude by the ultrasonic velocity and amplitude of the healthy part are obtained, and the range of concrete crushing is determined by the degree of decrease in the velocity ratio and amplitude ratio. And degree Because a constant, the site receives a compressive stress, it is possible to determine the range of compressive failure of the concrete, the range of decrease of the compressive strength, and the degree of reduction of the compressive strength.

  In this embodiment, the ultrasonic method is used to measure the ultrasonic velocity and the amplitude of the ultrasonic wave at each measurement position by measuring the ultrasonic velocity and the amplitude of the ultrasonic wave at each measurement position. The range and degree of concrete crushing were determined based on the speed ratio and amplitude ratio decrease at each measurement position obtained by dividing by speed and amplitude. The range and degree of concrete crushing may be determined only by the degree of decrease in the speed ratio at each measurement position obtained by measuring and dividing the ultrasonic speed at each measurement position by the ultrasonic speed at the sound part. Well, even in this way, it is possible to determine the range of compressive fracture of concrete, the range of decrease in compressive strength, and the degree of decrease in compressive strength.

1 Oscillator 2 Receiver C1 Hunch

Claims (2)

(1) An oscillator and a receiver by an ultrasonic method are arranged at a predetermined distance between the oscillator and the receiver in a sound part that is not subjected to compressive stress in a concrete structure, and an ultrasonic pulse is oscillated by the oscillator. By receiving the ultrasonic pulse by the oscillator, the ultrasonic velocity between the oscillator and the oscillator is measured,
(2) The same measurement as the above (1) is sequentially performed by moving the measurement position at a predetermined interval from the position where the compressive stress on the concrete surface is concentrated toward the sound part, and the oscillators at the respective measurement positions and Measure the ultrasonic velocity between the transducers,
(3) Dividing the ultrasonic velocity of each measurement position obtained by (2) above by the ultrasonic velocity of the sound part obtained by (1) above, obtaining the speed ratio of each measurement position;
(4) The range and degree of concrete crushing are determined based on the degree of decrease in the speed ratio at each measurement position obtained in (3) above.
A method for diagnosing a part subjected to compressive stress in a concrete structure characterized by the above. (1) An oscillator and a receiver by an ultrasonic method are arranged at a predetermined distance between the oscillator and the receiver in a sound part that is not subjected to compressive stress in a concrete structure, and an ultrasonic pulse is oscillated by the oscillator. By receiving the ultrasonic pulse by the receiver, the ultrasonic velocity between the oscillator and the receiver and the amplitude of the received ultrasonic wave are measured,
(2) The same measurement as the above (1) is sequentially performed by moving the measurement position at a predetermined interval from the position where the compressive stress on the concrete surface is concentrated toward the sound part, and the oscillators at the respective measurement positions and Measure the ultrasonic velocity between the transducers and the amplitude of the received ultrasonic waves,
(3) The ultrasonic velocity and amplitude of each measurement position obtained in (2) above are divided by the ultrasonic velocity and amplitude of the healthy part obtained in (1), respectively. Find the speed ratio and amplitude ratio of
(4) The range and degree of concrete crushing are determined based on the degree of decrease in the speed ratio and amplitude ratio at each measurement position obtained in (3) above.
A method for diagnosing a part subjected to compressive stress in a concrete structure characterized by the above.

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