CN112902889A - Double-channel thickness gauge and method for measuring longitudinal wave velocity in concrete through double-channel thickness gauge - Google Patents
Double-channel thickness gauge and method for measuring longitudinal wave velocity in concrete through double-channel thickness gauge Download PDFInfo
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- CN112902889A CN112902889A CN202110381382.7A CN202110381382A CN112902889A CN 112902889 A CN112902889 A CN 112902889A CN 202110381382 A CN202110381382 A CN 202110381382A CN 112902889 A CN112902889 A CN 112902889A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
- G01B17/02—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations for measuring thickness
Abstract
The invention provides a double-channel thickness gauge which comprises a columnar sleeve, an upper end cover and a lower end cover, wherein the upper end cover and the lower end cover are respectively and fixedly connected to the upper end and the lower end of the columnar sleeve, a WiFi antenna is arranged on the upper end cover, a system control module, a signal processing module, a power supply control module and a battery are installed in the columnar sleeve, and a channel 1 signal receiving sensor and a channel 2 signal receiving sensor are respectively embedded and installed at the bottom of the lower end cover through two sensor fixing shock absorption pads. The invention also provides a method for measuring the longitudinal wave velocity in the concrete by using the double-channel thickness gauge, which comprises the following steps: (1) acquiring two-channel waveform data X1(t) and X2(t) through a two-channel thickness gauge; (2) setting amplitude thresholds of X1(t) and X2(t) respectively, and calculating first peak times t1 and t2 when X1(t) and X2(t) exceed the amplitude thresholds; (3) calculating the wave speed of the surface wave; (4) the velocity of the longitudinal wave is calculated by multiplying the surface wave by a coefficient. The method has high measurement accuracy, is nondestructive measurement, and is convenient and quick to measure.
Description
Technical Field
The invention relates to the technical field of longitudinal wave parameter detection of concrete members, in particular to a double-channel thickness gauge and a method for measuring the longitudinal wave velocity in concrete by using the double-channel thickness gauge.
Background
In the calculation of the thickness of concrete pavements, tunnels, culvert linings and bridge beam slabs by an impact echo method, the velocity of a longitudinal wave of a stress wave propagating in a member is a parameter for calculating the thickness. In the prior art, there are four ways to obtain the velocity of longitudinal wave: 1. after a core sample of the concrete member is obtained through a core drilling machine, a longitudinal wave velocity of the concrete is obtained by using a nonmetal ultrasonic detector in a butt-measuring mode; 2. calibrating the longitudinal wave velocity by adopting an impact echo method according to the known thickness of the concrete member; 3. adopting a one-transmitting and two-receiving nonmetal ultrasonic detector to calculate the longitudinal wave velocity by using the distance difference between receiving probes of the channel 1 and the channel 2 and the time difference of the first wave; 4. a one-transmitting and one-receiving nonmetal ultrasonic detector is adopted, and a single-side leveling method is adopted to draw a time-distance graph or calculate the velocity of longitudinal waves by a regression analysis method by changing the distance between the inner edges of a transmitting probe and a receiving probe. Wherein, the method 1 needs to core in a damage mode, is low in efficiency, time-consuming and labor-consuming, and needs to perform subsequent repair treatment after core-taking, the thickness must be known in advance in the method 2, in practical situations, the thickness is not known in many places, and the position of the known thickness is not the same as the possible wave velocity of the position to be measured, the method 3 and the method 4 ensure that the longitudinal wave velocity calculation is accurate on the premise that the primary wave time is extracted, and the extraction of the longitudinal wave primary wave time is easy to make mistakes due to the fact that the energy of the longitudinal wave propagated on the concrete surface is smaller than that of the transverse wave and the surface wave, the attenuation of the longitudinal wave in the concrete surface is larger, and the influence of the concrete surface quality, and the longitudinal wave velocity calculated by the method 3 and the method 4 is only the longitudinal wave propagation velocity of the ultrasonic wave on the shallow layer of the concrete surface, and when the consistency of the material performance of the concrete member is poor, the longitudinal wave velocity on the surface layer is not consistent with the longitudinal, and the calculation of the actual thickness requires the velocity of the longitudinal wave through the concrete element. In the method 4, the multi-point test is required to be performed at each position to be tested, which is inefficient.
According to the propagation principle of stress waves in concrete, when the surface of the concrete is subjected to external transient excitation, such as knocking, three stress wave modes are generated in the concrete, namely longitudinal waves, transverse waves and surface waves. The surface wave is mainly propagated in a certain depth on the surface of the concrete, and the propagation speed of the surface wave has a certain relation with the longitudinal wave speed. The energy of the surface wave is maximum, so that the attenuation of the surface wave by the concrete is smaller than that of a transverse wave and a longitudinal wave, and the propagation depth of the surface wave on the surface of the concrete is deepened along with the reduction of the frequency, so that the surface wave with a proper frequency can be selected to be excited to have a certain propagation depth in the concrete, and the surface wave can be converted into the longitudinal wave to represent the speed of the longitudinal wave of the concrete with a certain depth.
The invention patent with publication number CN111964617A discloses a portable concrete thickness measuring device, which comprises a shell, wherein a sensor fixing shock pad is fixed at the bottom of the shell, a sound wave receiving sensor is embedded and mounted on the bottom surface of the sensor fixing shock pad, a system control module, a signal processing module, a power supply control module and a battery are mounted in the shell, the signal processing module is in electrical signal connection with the sound wave receiving sensor and used for amplifying and filtering received signals and transmitting the processed signals to the system control module, the system control module calculates according to the received signals to obtain the thickness of a concrete member, the power supply control module is used for controlling the battery to charge and supplying power to the whole device, and the battery is used for supplying power. This portable concrete thickness measurement device, the modularization degree is higher, convenient to use, and is efficient, is a non-damaged concrete thickness testing arrangement, can measure the thickness of concrete member anywhere in real time.
Disclosure of Invention
The invention aims to provide a double-channel thickness gauge and a method for quickly and accurately measuring the velocity of longitudinal waves at a to-be-measured thickness point by using the double-channel thickness gauge.
The invention discloses a double-channel thickness gauge which comprises a columnar sleeve, an upper end cover and a lower end cover, wherein the upper end cover and the lower end cover are respectively and fixedly connected to the upper end and the lower end of the columnar sleeve, a WiFi antenna is arranged on the upper end cover, a system control module, a signal processing module, a power supply control module and a battery are installed in the columnar sleeve, two sensor fixing shock absorption pads are fixed at the bottom of the lower end cover, a channel 1 signal receiving sensor and a channel 2 signal receiving sensor are respectively embedded and installed on the bottom surfaces of the two sensor fixing shock absorption pads, the channel 1 signal receiving sensor and the channel 2 signal receiving sensor are respectively connected with the signal processing module, and the system control module sends two-channel waveform data processed by the signal processing module to an intelligent mobile terminal through the WiFi antenna.
Further, the bottom of lower end cover still is provided with a shock attenuation supporting pad, the shock attenuation supporting pad bottom surface and the bottom surface of 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are in the coplanar, and 1 signal reception sensor of passageway, 2 signal reception sensors of passageway, shock attenuation supporting pad are triangle-shaped and arrange.
Further, the center distance between the channel 1 signal receiving sensor and the channel 2 signal receiving sensor is 100 mm.
The invention also provides a method for measuring the longitudinal wave velocity in the concrete by the double-channel thickness gauge, which comprises the following measuring steps:
(1) placing the double-channel thickness gauge on the surface of the concrete member, starting the double-channel thickness gauge, knocking the concrete member at one side, close to the channel 1 signal receiving sensor, on the axis of the channel 1 signal receiving sensor and the channel 2 signal receiving sensor, and acquiring two-channel waveform data X1(t) and X2(t) of the double-channel thickness gauge;
(2) setting amplitude thresholds of X1(t) and X2(t) respectively, wherein the amplitude thresholds are set according to the following principle: more than or equal to 3 times of signal noise and less than or equal to 50% of the maximum amplitude value, and respectively calculating first peak time t1 and t2 when X1(t) and X2(t) exceed the amplitude threshold values;
(3) calculating the wave speed Vr of the surface wave:
wherein L is the center distance between the channel 1 signal receiving sensor and the channel 2 signal receiving sensor;
(4) calculating the longitudinal wave velocity Vp by adopting the following formula: vp is Vr × α, a is a coefficient,
where u is the poisson's ratio of the concrete member.
Further, in step (1), if there is clipping in the waveform data X1(t), X2(t), the dual-channel thickness gauge gain is reduced until waveform data X1(t), X2(t) without clipping is obtained.
The dual-channel thickness gauge can synchronously acquire the waveform data of the two channels, has higher modularization degree and convenient use, extracts the wave crests of the surface waves of the two channels to be used as time difference calculation, and converts the surface waves into longitudinal waves to represent the longitudinal wave speed of the concrete at a certain depth, so that the dual-channel thickness gauge has high measurement accuracy, is nondestructive measurement, and is convenient and rapid to measure and high in efficiency.
Drawings
Fig. 1 is a schematic structural diagram of the dual-channel thickness gauge of the present invention.
Fig. 2 is a schematic bottom view of the dual channel thickness gauge of the present invention.
FIG. 3 is a flow chart of the method for measuring the velocity of longitudinal waves in concrete by a two-channel thickness gauge according to the present invention.
FIG. 4 is a waveform diagram of X1(t) read by a two-channel thickness gauge in an embodiment of the present invention.
FIG. 5 is a waveform diagram of X2(t) read by a two-channel thickness gauge in an embodiment of the present invention.
Fig. 6 is a waveform diagram read by a non-metallic sonic apparatus in an embodiment of the present invention.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
As shown in fig. 1 and 2, the binary channels calibrator of this embodiment, including column sleeve and upper end cover, the lower end cover at both ends about column sleeve respectively fixed connection, be equipped with the wiFi antenna on the upper end cover, install system control module, signal processing module, power control module, battery in the column sleeve, the bottom of lower end cover is fixed with two fixed shock pads of sensor, 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are installed in the embedding respectively to two fixed shock pads bottom surfaces of sensor, 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are connected with signal processing module respectively, two channel waveform data after signal processing module will be handled to intelligent mobile terminal through the wiFi antenna by system control module. The bottom of lower end cover still is provided with a shock attenuation supporting pad, the shock attenuation supporting pad bottom surface and the bottom surface of 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are in the coplanar, and 1 signal reception sensor of passageway, 2 signal reception sensors of passageway, shock attenuation supporting pad are triangle-shaped and arrange.
As a preferred embodiment of the present invention, the center distance between the channel 1 signal receiving sensor and the channel 2 signal receiving sensor is 100 mm.
As shown in fig. 3, the method for measuring the longitudinal wave velocity in concrete by using the dual-channel thickness gauge of the present invention includes the above dual-channel thickness gauge, and the measuring steps are as follows:
(1) placing the dual-channel thickness gauge on the surface of a concrete member, starting the dual-channel thickness gauge, knocking the concrete member on the side, close to the channel 1 signal receiving sensor, on the axis of the channel 1 signal receiving sensor and the channel 2 signal receiving sensor, to obtain two-channel waveform data X1(t) and X2(t) of the dual-channel thickness gauge, and if clipping exists in the waveform data X1(t) and X2(t), reducing the gain of the dual-channel thickness gauge until waveform data X1(t) and X2(t) without clipping are obtained;
(2) setting amplitude thresholds of X1(t) and X2(t) respectively, wherein the amplitude thresholds are set according to the following principle: more than or equal to 3 times of signal noise and less than or equal to 50% of the maximum amplitude value, and respectively calculating first peak time t1 and t2 when X1(t) and X2(t) exceed the amplitude threshold values;
(3) calculating the wave speed Vr of the surface wave:
wherein L is a channel 1 signal receiving sensor and a channel 2 signal receiving sensorThe center distance therebetween;
(4) calculating the longitudinal wave velocity Vp by adopting the following formula: vp is Vr × α, a is a coefficient,
where u is the poisson's ratio of the concrete member.
Referring to fig. 4 and 5, in the present embodiment, a concrete cube of 20cm by 20cm is selected as a concrete member to be measured, and the measuring steps are as follows:
(1) placing the double-channel thickness gauge on the surface of the concrete cube, starting the double-channel thickness gauge, and knocking the surface of the concrete cube by using small balls with the diameter of 8mm at the positions 5cm away from the channel 1 signal receiving sensor on the axes of the channel 1 signal receiving sensor and the channel 2 signal receiving sensor;
(2) reading two-channel waveform data X1(t) and X2(t) of the two-channel thickness gauge, and if clipping exists in X1(t) and X2(t), reducing the gain of the gauge until non-clipped waveform data X1(t) and X2(t) are obtained;
(3) setting the X1(t) and X2(t) amplitude thresholds to be 10% of the maximum amplitude value respectively;
(4) respectively calculating first peak times t1 and t2 of X1(t) and X2(t) exceeding amplitude thresholds, wherein t1 is 59us, and t2 is 97us, as shown in fig. 2 and fig. 3;
(5) calculating the wave velocity of surface waves
Wherein L is 100mm, t1 is 59us, t2 is 97 us;
(6) calculating the velocity of longitudinal wave
Wherein the Poisson's ratio is 0.2.
The longitudinal wave velocity V of the 20cm by 20cm concrete cube is measured by a pair measuring method by a nonmetal ultrasonic detector, wherein t is 42.5us, and the longitudinal wave velocity V is 20cm/t 4705.9m/s, as shown in figure 3.
Therefore, the relative error of the wave speed obtained by the device and the method for measuring the longitudinal wave speed in the concrete through the two-channel thickness gauge compared with the actual wave speed in the concrete is 100 (4699.3-4705.9)/4705.9 which is-0.14 percent.
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (5)
1. The utility model provides a binary channels calibrator, includes column sleeve and upper end cover, the lower end cover at both ends about column sleeve respectively fixed connection, be equipped with the wiFi antenna on the upper end cover, install system control module, signal processing module, power control module, battery in the column sleeve, its characterized in that: the bottom of lower extreme cover is fixed with two fixed shock pads of sensor, 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are installed in the fixed shock pad bottom surface embedding respectively of two sensors, 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are connected with signal processing module respectively, two passageway waveform data after signal processing module handles will be passed through the wiFi antenna and sent to intelligent mobile terminal to system control module.
2. The dual channel thickness gauge of claim 1, wherein: the bottom of lower end cover still is provided with a shock attenuation supporting pad, the shock attenuation supporting pad bottom surface and the bottom surface of 1 signal reception sensor of passageway, 2 signal reception sensors of passageway are in the coplanar, and 1 signal reception sensor of passageway, 2 signal reception sensors of passageway, shock attenuation supporting pad are triangle-shaped and arrange.
3. The dual channel thickness gauge of claim 1, wherein: the center distance between the channel 1 signal receiving sensor and the channel 2 signal receiving sensor is 100 mm.
4. A method for measuring the velocity of longitudinal waves in concrete by means of a two-channel thickness gauge, characterized in that it comprises the two-channel thickness gauge of claim 1 or 2, the measuring steps being as follows:
(1) placing the double-channel thickness gauge on the surface of the concrete member, starting the double-channel thickness gauge, knocking the concrete member at one side, close to the channel 1 signal receiving sensor, on the axis of the channel 1 signal receiving sensor and the channel 2 signal receiving sensor, and acquiring two-channel waveform data X1(t) and X2(t) of the double-channel thickness gauge;
(2) setting amplitude thresholds of X1(t) and X2(t) respectively, wherein the amplitude thresholds are set according to the following principle: more than or equal to 3 times of signal noise and less than or equal to 50% of the maximum amplitude value, and respectively calculating first peak time t1 and t2 when X1(t) and X2(t) exceed the amplitude threshold values;
(3) calculating the wave speed Vr of the surface wave:
wherein L is the center distance between the channel 1 signal receiving sensor and the channel 2 signal receiving sensor;
(4) calculating the longitudinal wave velocity Vp by adopting the following formula: vp is Vr × α, a is a coefficient,
where u is the poisson's ratio of the concrete member.
5. The method for measuring the longitudinal wave velocity in the concrete through the dual-channel thickness gauge according to claim 4, wherein the method comprises the following steps: in the step (1), if clipping exists in the waveform data X1(t) and X2(t), the gain of the dual-channel thickness gauge is reduced until the waveform data X1(t) and X2(t) without clipping are obtained.
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| CN202110381382.7A CN112902889A (en) | 2021-04-09 | 2021-04-09 | Double-channel thickness gauge and method for measuring longitudinal wave velocity in concrete through double-channel thickness gauge |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114396861A (en) * | 2022-01-26 | 2022-04-26 | 北京海创高科科技有限公司 | Double-channel reinforced concrete reinforcement structure scanner and scanning method |
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| TWI231362B (en) * | 2002-04-12 | 2005-04-21 | Yi-Ching Lin | Method for measuring speed of longitudinal wave and thickness inside concrete plate by using stress wave |
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| CN107192624A (en) * | 2017-03-22 | 2017-09-22 | 国家电网公司 | A kind of concrete strength detecting method based on impact elasticity ripple |
| CN111964617A (en) * | 2020-09-17 | 2020-11-20 | 湖南芯仪电子科技有限公司 | Portable concrete thickness measuring device |
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2021
- 2021-04-09 CN CN202110381382.7A patent/CN112902889A/en not_active Withdrawn
Patent Citations (4)
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| TWI231362B (en) * | 2002-04-12 | 2005-04-21 | Yi-Ching Lin | Method for measuring speed of longitudinal wave and thickness inside concrete plate by using stress wave |
| CN203037849U (en) * | 2012-12-31 | 2013-07-03 | 汕头市超声仪器研究所有限公司 | Ultrasonic thickness gauge |
| CN107192624A (en) * | 2017-03-22 | 2017-09-22 | 国家电网公司 | A kind of concrete strength detecting method based on impact elasticity ripple |
| CN111964617A (en) * | 2020-09-17 | 2020-11-20 | 湖南芯仪电子科技有限公司 | Portable concrete thickness measuring device |
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Application publication date: 20210604 |