CN107894459B - Prestressed duct grouting compactness testing method based on fluctuation signal characteristic analysis - Google Patents
Prestressed duct grouting compactness testing method based on fluctuation signal characteristic analysis Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
- G01N29/046—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks using the echo of particles imparting on a surface; using acoustic emission of particles
Abstract
The invention discloses a method for testing the grouting compactness of a prestressed duct based on the characteristic analysis of a fluctuation signal, wherein a test line or a test surface is arranged in a test area appointed by a tested object; placing a fluctuation signal pickup device on the arranged measuring points, and exciting an incident fluctuation signal by using a signal source generating device; the wave signal pickup device picks up a mixed wave signal formed by recombining the reflected wave signal and the incident wave signal; the signal conversion and conditioning device converts the signal from an analog signal to a digital signal; and carrying out characteristic analysis on the mixed fluctuation signals, and judging the grouting condition inside the pore passage. The method comprises the steps of analyzing characteristic changes generated after superposition of reflection fluctuation signals and incidence fluctuation signals when the incidence fluctuation signals encounter defects or reflection surfaces with large impedance differences, and judging whether grouting defects exist in the inner part of a pore passage of a tested object or not by picking and analyzing the superposed signals and taking the characteristic changes as main basis; the test method is rigorous and has high reliability, so that the final judgment result is more accurate.
Description
Technical Field
The invention relates to the technical field of engineering quality detection, in particular to a method for testing the grouting compactness of a prestressed duct based on fluctuation signal characteristic analysis.
Background
With the rapid development of our country society, the traffic demand is gradually expanding, and the country also invests huge funds in the field of basic traffic construction, and because our country has complex and changeable landforms, rivers and mountains are vertical and horizontal, the bridge becomes an important link for connecting various types of cutting, and the bridge is widely applied to prolonging the service life, span, load capacity and post-tensioning prestress of the bridge.
In order to ensure that the prestressed steel strand effectively plays a role for a long time in the service process of a bridge, the grouting quality is the most critical factor, if the prestressed duct grouting is not compact, on one hand, the dispersion of the stress of the bridge is influenced to form a stress concentration area, so that the structure is damaged, on the other hand, the steel strand can be quickly corroded in a high-stress state, once the load capacity of the broken bridge is greatly reduced, and safety accidents are easily caused, so that the effective detection on the compactness of the duct grouting is very important, once a problem is found, engineering technicians can be guided to timely repair, and major safety accidents are avoided.
Disclosure of Invention
Based on the above, it is necessary to provide a method for testing the grouting compactness of the prestressed duct based on the characteristic analysis of the fluctuation signal, which includes generating an incident fluctuation signal by using a specially-made rigid hammer in a certain area of the duct of the tested object, analyzing the characteristic variation generated by superimposing the incident fluctuation signal and a reflected fluctuation signal generated when the incident fluctuation signal encounters a defect or when a reflection surface with a large impedance difference exists, and judging whether the grouting defect exists in the inner part of the duct of the tested object by picking up and analyzing the superimposed signals based on the characteristic variation as a main basis; the test method is rigorous and has high reliability, so that the final judgment result is more accurate.
The technical scheme of the invention is as follows:
a prestressed duct grouting compactness testing method based on fluctuation signal characteristic analysis comprises the following steps:
a. arranging a test line or a test surface in a test area designated by a tested object; wherein the test surface is formed by fitting a plurality of measuring lines;
b. placing a fluctuation signal pickup device on the arranged measuring points, and exciting an incident fluctuation signal by using a signal source generating device;
c. the wave signal pickup device picks up a mixed wave signal formed by recombining the reflected wave signal and the incident wave signal and transmits the mixed wave signal to the signal conversion conditioning device;
d. the signal conversion conditioning device converts the mixed fluctuation signal from an analog signal to a digital signal and conditions the digital signal;
e. and carrying out characteristic analysis on the picked mixed fluctuation signals, and judging the grouting condition inside the pore passage according to the analyzed characteristics.
The method takes the grouting compactness of the prestressed duct as an explanation foundation, and also comprises the steps of detecting the internal defects of the concrete and the compactness of the bonding surface of the secondary poured concrete; the method adopts a signal source generating device, when incident waves encounter the phenomenon of pore channel incompactness in the transmission process, fluctuation signals are reflected, recombined with the incident fluctuation signals and continuously transmitted, and the grouting quality problem inside the pore channel is judged by analyzing the characteristic difference of the recombined mixed fluctuation signals; specifically, a specially-made rigid small hammer is adopted to generate an incident fluctuation signal in a certain area of a measured object pore canal, characteristic changes generated after the incident fluctuation signal is superposed with a reflection fluctuation signal when the incident fluctuation signal encounters a defect or a reflection surface with large impedance difference are analyzed, and whether grouting defects exist in the inner part of the measured object pore canal or not is judged by taking the characteristic changes as the main basis through picking and analyzing the superposed signal; the test method is rigorous and has high reliability, so that the final judgment result is more accurate.
As a further optimization of the scheme, in the step a, the distance between the arranged measuring points is not more than 1.5 times of the distance from the test surface to the defect of the measured object; the testing area is arranged at the position shifted upwards or downwards by d/4 in the area between the central line and the upper edge of the measured object, or at the position shifted upwards or downwards by d/4 in the area between the central line and the lower edge of the measured object; wherein d is the diameter of the pore passage of the measured object.
Measuring point arrangement, as shown in fig. 2a and 2b, the point distribution density can be adjusted according to the requirement of the measuring precision, the point distribution distance is not more than 1.5 times of the distance between the measuring surface and the pore canal under the general condition, the point distribution position is combined with the detection capability of the wave, is not arranged at the central line position of the measuring object (pore canal), and is arranged at the position where the area between the central line and the upper edge or the lower edge is translated upwards or downwards by d/4; the wave signal pickup device can accurately pick up the mixed wave signal formed by recombining the incident wave signal and the reflected wave signal, and the precision of the tested wave signal is improved.
As a further optimization of the above scheme, in step b, the signal source generating device performs oscillation on the same line with a distance D from the fluctuation signal pickup device; where D is 0.3 λ +0.05, λ being the wavelength of the incident wobble signal.
Picking up the wave signalThe device is placed on a well-arranged measuring point, a variable-frequency signal source generating device is adopted to excite vibration on the same straight line away from a distance D of a fluctuation signal pickup device, wherein the distance D is 0.3 lambda +0.05, lambda is the wavelength of an incident fluctuation signal, the lambda is indefinite and is related to the diameter material of a sphere of an excitation hammer, and the excitation frequency is generally
DcIs the diameter of the sphere of the vibration exciter,
in the vibration generating process, a vibration generating device or a vibration generating mode with high reflectivity (R ^ f, R is the signal reflectivity, and f is the signal incidence frequency) is preferentially adopted to improve the reflectivity of the signal when encountering impedance difference, and the maximum reflectivity can be calculated by a general theoretical formula or obtained by field tests.
As a further optimization of the scheme, in the step b, the signal source generating device is a shock excitation hammer made of a steel material, and the hardness of the shock excitation hammer is HRC28-HRC 35; the excitation hammer comprises a ball body, a tension spring and a hammer handle, wherein the ball body is connected with the hammer handle through the tension spring, and the diameter of the ball body is 6-28 mm.
The steel vibration hammer comprising the ball body, the tension spring and the hammer handle is used as a signal source generating device, and the ball body is connected with the hammer handle through the tension spring, so that the signal source generating device can effectively suppress interference signals behind pulse signals, provides a steady-state input function for a system, and is convenient for signal analysis.
As a further optimization of the above solution, said step e comprises the steps of:
receiving the conditioned mixed fluctuation signal, and analyzing the mixed fluctuation signal;
and evaluating the grouting quality problem in the pore canal of the tested object according to the characteristic change of the analyzed mixed fluctuation signal.
Picking up a mixed fluctuation signal obtained by recombining and mixing an incident fluctuation signal and a reflected fluctuation signal, and analyzing the characteristics of the mixed fluctuation signal so as to judge whether the grouting defect exists in the pore passage or not; the accuracy of evaluating and judging the grouting quality problem in the pore passage is improved, and the quality detection of the working condition is more reliable.
As a further optimization of the above solution, the step e further comprises the following steps:
and judging the grouting quality problem of the pore passage of the measured object by analyzing the difference between the incident fluctuation signal and the mixed fluctuation signal and the grouting compact area.
In actual engineering, the prestressed duct material mainly exists in a mode 3, wherein the first type is an iron sheet corrugated pipe, the second type is a PVC corrugated pipe, and the third type is a pipe-free structure in a drawing mode, and the main difference is that the reflection coefficient of a reflection surface has a certain difference; when the pore canal has no grouting or the grouting compactness is low, the system characteristics of the 3 pore canal types are basically consistent (slightly different system characteristics due to different corrugated pipe materials) on the premise of the same structural form, the response of the reflected signal is also basically consistent, and the amplitude (basically consistent characteristics can be generated due to the frequency spectrum and the phase in the structural range influenced by the harmonic wave) is basically consistent; when the pore canal grouting is dense and the slurry reaches the strength (M50) required by the design, 3 pore canal type signals are different, but are different from those when no grouting is available or the grouting compactness is low, and the overall characteristics of the system are changed at the moment, so that the amplitude of a reflection fluctuation signal is changed (due to the fact that the frequency spectrum and the phase within the structural range are simultaneously changed under the influence of harmonic waves); according to the difference of signal characteristics of the compact pore channel and the pore channel with the defect in the detection process, the defect state distribution of the prestressed pore channel in the length direction, namely the compactness condition of the detection area, can be accurately judged.
As a further optimization of the above scheme, the method further comprises the following steps:
and the mixed fluctuation signal is transmitted to a signal display device for signal display after signal conversion and conditioning. The signal display device is used for displaying the conditioned mixed fluctuation signals, and is convenient for workers to observe and analyze.
The invention has the beneficial effects that:
1. according to the method, a signal source generating device is adopted, when the incident wave encounters the phenomenon that the pore channel is not compact in the propagation process, the fluctuation signal is reflected, recombined with the incident fluctuation signal and continuously propagated, and the grouting quality problem inside the pore channel is judged by analyzing the characteristic difference of the recombined mixed fluctuation signal.
2. The distribution density can be adjusted according to the requirement of test precision, the distribution distance is not more than 1.5 times of the distance between the test surface and the pore canal, and the distribution position is arranged at the position of the upward or downward translation d/4 of the area between the central line and the upper edge or the lower edge in combination with the detection capability of the wave; the wave signal pickup device can accurately pick up the mixed wave signal formed by recombining the incident wave signal and the reflected wave signal, and the precision of the tested wave signal is improved.
3. The method comprises the steps of placing a fluctuation signal pickup device on a distributed measuring point, exciting on the same straight line far away from the fluctuation signal pickup device by using a variable-frequency signal source generating device, wherein the distance D is 0.3 lambda +0.05, preferentially adopting an excitation device or an excitation mode with high reflectivity (R is in proportion to f, R is signal reflectivity, and f is signal incidence frequency) in the oscillation process, and effectively improving the reflectivity of the signal when encountering impedance difference.
4. Analyzing the characteristics of the mixed fluctuation signal so as to judge whether the grouting defect exists in the pore passage; the accuracy of evaluating and judging the grouting quality problem in the pore passage is improved, and the quality detection of the working condition is more reliable.
5. According to the detection process, the defect state distribution of the prestressed duct in the length direction, namely the compactness condition of the detection area, can be accurately judged through the difference of signal characteristics of the compact duct and the duct with the defect, so that the detection accuracy and the safety are improved.
Drawings
FIG. 1 is a flow chart of a method for testing the grouting compactness of a prestressed duct based on fluctuation signal characteristic analysis according to an embodiment of the invention;
FIG. 2a is a side view of a test area according to an embodiment of the present invention;
FIG. 2b is a front view of a test area according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a relationship between a test point and a wave signal generation point according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a signal source generating device according to an embodiment of the present invention;
FIG. 5 is a schematic illustration of the propagation of a fluctuating signal when the duct is not grouted or has poor grouting quality according to an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating propagation of a fluctuation signal in real time of grouting density of a duct according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a single degree of freedom vibration system model according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of signal superposition of an incident wave signal and a reflected wave signal according to an embodiment of the present invention;
FIG. 9 is a schematic illustration of the harmonic effects described in the embodiments of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Examples
As shown in fig. 1, a method for testing the grouting compactness of a prestressed duct based on fluctuation signal characteristic analysis includes the following steps:
a. arranging a test line or a test surface in a test area designated by a tested object; wherein the test surface is formed by fitting a plurality of measuring lines;
b. placing a fluctuation signal pickup device on the arranged measuring points, and exciting an incident fluctuation signal by using a signal source generating device;
c. the wave signal pickup device picks up a mixed wave signal formed by recombining the reflected wave signal and the incident wave signal and transmits the mixed wave signal to the signal conversion conditioning device;
d. the signal conversion conditioning device converts the mixed fluctuation signal from an analog signal to a digital signal and conditions the digital signal;
e. and carrying out characteristic analysis on the picked mixed fluctuation signals, and judging the grouting condition inside the pore passage according to the analyzed characteristics.
The method takes the grouting compactness of the prestressed duct as an explanation foundation, and also comprises the steps of detecting the internal defects of the concrete and the compactness of the bonding surface of the secondary poured concrete; the method adopts a signal source generating device, when incident waves encounter the phenomenon of pore channel incompactness in the transmission process, fluctuation signals are reflected, recombined with the incident fluctuation signals and continuously transmitted, and the grouting quality problem inside the pore channel is judged by analyzing the characteristic difference of the recombined mixed fluctuation signals; specifically, a specially-made rigid small hammer is adopted to generate an incident fluctuation signal in a certain area of a measured object pore canal, characteristic changes generated after the incident fluctuation signal is superposed with a reflection fluctuation signal when the incident fluctuation signal encounters a defect or a reflection surface with large impedance difference are analyzed, and whether grouting defects exist in the inner part of the measured object pore canal or not is judged by taking the characteristic changes as the main basis through picking and analyzing the superposed signal; the test method is rigorous and has high reliability, so that the final judgment result is more accurate.
In one embodiment, as shown in fig. 2a and 2b, in step a, the measuring point spacing is not more than 1.5 times of the distance from the test surface to the measured object; the testing area is arranged at the position shifted upwards or downwards by d/4 in the area between the central line and the upper edge of the measured object, or at the position shifted upwards or downwards by d/4 in the area between the central line and the lower edge of the measured object; wherein d is the diameter of the pore passage of the measured object.
Measuring point arrangement, wherein the point arrangement density can be adjusted according to the requirement of test precision, the point arrangement distance is not more than 1.5 times of the distance from the test surface to the pore canal under the general condition, the point arrangement position is combined with the detection capability of the wave, is not arranged at the position of the central line of the test object (pore canal), and is arranged at the position of the upward or downward translation d/4 of the area between the central line and the upper edge or the lower edge; the wave signal pickup device can accurately pick up the mixed wave signal formed by recombining the incident wave signal and the reflected wave signal, and the precision of the tested wave signal is improved.
In another embodiment, as shown in fig. 3, in step b, the signal source generating device performs oscillation on the same line with a distance D from the wave signal pickup device; where D is 0.3 λ +0.05, λ being the wavelength of the incident wobble signal.
The method comprises the steps of placing a fluctuation signal pickup device on a distributed measuring point, and exciting on the same straight line far away from the fluctuation signal pickup device by using a variable-frequency signal source generating device, wherein the distance D is 0.3 lambda +0.05, lambda is the wavelength of an incident fluctuation signal, the lambda is indefinite and is related to the diameter material of a sphere of an exciting hammer, and the exciting frequency is generally equal to
DcIs the diameter of the sphere of the vibration exciter,
in the vibration generating process, a vibration generating device or a vibration generating mode with high reflectivity (R ^ f, R is the signal reflectivity, and f is the signal incidence frequency) is preferentially adopted to improve the reflectivity of the signal when encountering impedance difference, and the maximum reflectivity can be calculated by a general theoretical formula or obtained by field tests.
In another embodiment, as shown in fig. 4, in step b, the signal source generating device is a vibration exciter made of steel material, and the hardness of the vibration exciter is HRC 28; the excitation hammer comprises a ball body, a tension spring and a hammer handle, the ball body is connected with the hammer handle through the tension spring, and the diameter of the ball body is 6 mm.
In another embodiment, as shown in fig. 4, in step b, the signal source generating device is a vibration exciter made of steel material, and the hardness of the vibration exciter is HRC 35; the excitation hammer comprises a ball body, a tension spring and a hammer handle, the ball body is connected with the hammer handle through the tension spring, and the diameter of the ball body is 28 mm.
In another embodiment, as shown in fig. 4, in step b, the signal source generating device is a vibration exciter made of steel material, and the hardness of the vibration exciter is HRC 32; the excitation hammer comprises a ball body, a tension spring and a hammer handle, the ball body is connected with the hammer handle through the tension spring, and the diameter of the ball body is 17 mm.
The steel vibration hammer comprising the ball body, the tension spring and the hammer handle is used as a signal source generating device, and the ball body is connected with the hammer handle through the tension spring, so that the signal source generating device can effectively suppress interference signals behind pulse signals, provides a steady-state input function for a system, and is convenient for signal analysis.
In another embodiment, said step e comprises the steps of:
receiving the conditioned mixed fluctuation signal, and analyzing the mixed fluctuation signal;
and evaluating the grouting quality problem in the pore canal of the tested object according to the characteristic change of the analyzed mixed fluctuation signal.
Picking up a mixed fluctuation signal obtained by recombining and mixing an incident fluctuation signal and a reflected fluctuation signal, and analyzing the characteristics of the mixed fluctuation signal so as to judge whether the grouting defect exists in the pore passage or not; the accuracy of evaluating and judging the grouting quality problem in the pore passage is improved, and the quality detection of the working condition is more reliable.
In another embodiment, the step e further comprises the steps of:
and judging the grouting quality problem of the pore passage of the measured object by analyzing the difference between the incident fluctuation signal and the mixed fluctuation signal and the grouting compact area.
In actual engineering, the prestressed duct material mainly exists in a mode 3, wherein the first type is an iron sheet corrugated pipe, the second type is a PVC corrugated pipe, and the third type is a pipe-free structure in a drawing mode, and the main difference is that the reflection coefficient of a reflection surface has a certain difference; when the pore canal has no grouting or the grouting compactness is low, the system characteristics of the 3 pore canal types are basically consistent (slightly different system characteristics due to different corrugated pipe materials) on the premise of the same structural form, the response of the reflected signal is also basically consistent, and the amplitude (basically consistent characteristics can be generated due to the frequency spectrum and the phase in the structural range influenced by the harmonic wave) is basically consistent; when the pore canal grouting is dense and the slurry reaches the strength (M50) required by the design, 3 pore canal type signals are different and are different from those without grouting or when the grouting compactness is low, the overall characteristics of the system are changed, and the amplitude of the reflection fluctuation signal is changed (due to the fact that the frequency spectrum and the phase within the structural range are changed at the same time under the influence of harmonic waves); according to the difference of signal characteristics of the compact pore channel and the pore channel with the defect in the detection process, the defect state distribution of the prestressed pore channel in the length direction, namely the compactness condition of the detection area, can be accurately judged.
In another embodiment, the method further comprises the following steps:
and the mixed fluctuation signal is transmitted to a signal display device for signal display after signal conversion and conditioning. The signal display device is used for displaying the conditioned mixed fluctuation signals, and is convenient for workers to observe and analyze.
In the invention, a signal source generating device is adopted, an incident fluctuation signal is reflected when encountering a pore channel non-compact phenomenon in the transmission process, and is recombined with the incident fluctuation signal and continuously transmitted, the problem of grouting quality inside the pore channel is judged by analyzing the characteristic difference of the recombined signal, and the prestressed pore channel material mainly exists in a form of 3 in the practical engineering:
the first is a corrugated pipe made of iron sheet, the second is a corrugated pipe made of PVC, and the third is a pipe-free structure in a drawing mode.
Reflection coefficient of fluctuation theory signal: r _ b ═ ρ vA (formula 1), where ρ is the density of the material, v is the propagation velocity of the wave signal in the medium, and a is the cross-sectional area of the medium;
as the reflection coefficient difference between air and concrete is large when no grouting is carried out on 3 types of the pore channels or the grouting quality is poor, as shown in figure 5, the signals are almost totally reflected at the defect position, at the moment, the reflection fluctuation signals (including harmonic reflection signals) and the incidence fluctuation signals are recombined to form new mixed fluctuation signals to be transmitted in the structure, a signal superposition schematic diagram of the incidence fluctuation signals and the reflection fluctuation signals as shown in figure 8 is obtained, and whether grouting defects exist in the pore channels can be judged by picking up the characteristics of the new mixed fluctuation signals and analyzing the characteristics.
The concrete belongs to a solid structure, can be regarded as a uniform elastic body in an acting force range, a wave signal can be regarded as a damping attenuation system when propagating in the concrete, and the damping attenuation system can be equivalent to a single-free system as shown in figure 7, wherein the damping attenuation system occurs at a signal sourceF (t) F produced by the device0The wave differential equation under the action of sin ω t function signal can be expressed as:
setting: incident ripple signal formed by input signal:
reflected wave signal at the tunnel:
recombined mixed fluctuation signal: y isx＝X1+X2(formula 5)
Wherein the content of the first and second substances,
is the relative damping coefficient of the material,
is the critical damping coefficient, B is the amplitude,
is a phase angle;
the following can be obtained from equations 2 and 4:
in addition, a harmonic analysis method is adopted to expand the reflection fluctuation signals according to Fourier series, and the following results are obtained:
wherein the content of the first and second substances,
j is 1, 2, 3.. times; taking the balance point as the origin of coordinates, equation 8 can be expressed as:
as can be seen from expressions 6, 7, and 9, the amplitude, phase, and frequency of the reflected wave signal are related to the characteristics (m, k, and c) of the structure itself.
As shown in fig. 5, when the pore channels have no grouting or have low grouting compactness, the system characteristics of the 3 pore channel types are substantially consistent (slightly different system characteristics due to different corrugated pipe materials) on the premise of the same structural form, and the reflected fluctuation signal responses are also substantially consistent, which is represented by substantially consistent amplitudes (as shown in fig. 9, the frequency spectrum and the phase within the structural range are substantially consistent at the same time due to the influence of harmonics);
as shown in fig. 6, when the pore canal grouting is dense and the slurry reaches the strength (M50) required by the design, the 3 pore canal type signals are different, but are different from those without grouting or when the grouting compactness is low, at this time, the overall characteristics k, M, and c of the system are changed, so that the amplitude of the reflected fluctuation signal is changed (due to the fact that the frequency spectrum and the phase within the structural range are changed at the same time under the influence of the harmonic wave);
according to the difference of signal characteristics of the compact pore channel and the pore channel with the defect in the detection process, the defect state distribution of the prestressed pore channel in the length direction, namely the compactness condition of the detection area, can be accurately judged.
The above-mentioned embodiments only express the specific embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (4)
1. A prestressed duct grouting compactness testing method based on fluctuation signal characteristic analysis is characterized by comprising the following steps:
a. arranging a test line or a test surface in a test area designated by a tested object; wherein the test surface is formed by fitting a plurality of measuring lines;
b. placing a fluctuation signal pickup device on the arranged measuring points, and exciting an incident fluctuation signal by using a signal source generating device;
c. the wave signal pickup device picks up a mixed wave signal formed by recombining the reflected wave signal and the incident wave signal and transmits the mixed wave signal to the signal conversion conditioning device;
d. the signal conversion conditioning device converts the mixed fluctuation signal from an analog signal to a digital signal and conditions the digital signal;
e. carrying out feature analysis on the picked mixed fluctuation signals to obtain overall system characteristics, wherein the overall system characteristics comprise: k. m, c, k are system rigidity, c is system damping, m is the vibration structure mass to judge the inside slip casting situation of pore through the characteristic of analyzing out, specifically do: based on a specific calculation process, obtaining specific k, m and c of the structure by reflecting the amplitude, phase and frequency of a fluctuation signal, wherein k is system rigidity, c is system damping and m is the mass of a vibration structure body; judging the defect state distribution of the prestressed duct in the length direction, namely the compactness condition of the detection area according to the difference of signal characteristics of the compact duct and the duct with the defect in the detection process;
in the step a, the distance between the arranged measuring points is not more than 1.5 times of the distance from the test surface to the defect of the measured object; the testing area is arranged at a position shifted upwards by d/4 of the area between the central line and the upper edge of the measured object or at a position shifted downwards by d/4 of the area between the central line and the lower edge of the measured object; wherein d is the diameter of the pore channel of the measured object;
in the step b, the signal source generating device generates vibration on the same line with the distance D from the fluctuation signal pickup device; wherein, D is 0.3 lambda +0.05, and lambda is the wavelength of the incident fluctuation signal;
in the step b, the signal source generating device is a vibration exciter made of steel materials, and the hardness of the vibration exciter is HRC28-HRC 35; the excitation hammer comprises a ball body, a tension spring and a hammer handle, wherein the ball body is connected with the hammer handle through the tension spring, and the diameter of the ball body is 6-28 mm.
2. The method for testing the grouting compactness of the prestressed duct based on the fluctuation signal characteristic analysis according to claim 1, wherein the step e comprises the following steps: receiving the conditioned mixed fluctuation signal, and analyzing the mixed fluctuation signal; and evaluating the grouting quality problem in the pore canal of the tested object according to the characteristic change of the analyzed mixed fluctuation signal.
3. The method for testing the grouting compactness of the prestressed duct based on the fluctuation signal characteristic analysis according to claim 1, wherein the step e further comprises the following steps: and judging the grouting quality problem of the pore passage of the measured object by analyzing the difference between the incident fluctuation signal and the mixed fluctuation signal and the grouting compact area.
4. The method for testing the grouting compactness of the prestressed duct based on the fluctuation signal characteristic analysis according to claim 1, further comprising the step of transmitting the mixed fluctuation signal to a signal display device for signal display after signal conversion and conditioning.
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| CN113218986B (en) * | 2021-04-09 | 2023-05-12 | 河南五建建设集团有限公司 | System and method for detecting compactness after prestress grouting construction |
| CN114280154B (en) * | 2021-12-21 | 2023-08-18 | 重庆交大建设工程质量检测中心有限公司 | Grouting compactness superposition imaging detection method for prestressed concrete pipeline |
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