A prestressed structure hole pressure grouting compactness detection method

Abstract

The application provides a prestressed structure hole pressure grouting density detection system and method. The signal excitation device is adopted to generate an impact elastic wave at an excitation point of the prestressed structure hole, and then the signal characteristics of the impact reflected wave at a symmetrical position relative to the monitored point are analyzed to determine the pressure grouting density of the monitored point in the prestressed structure hole. The application solves the problems of low detection efficiency and uncontrollable vibration source signal of the pressure grouting density detection device in the prior art, and has the technical effects of improving the detection efficiency of the pressure grouting density detection device and controlling the vibration source signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering construction quality detection, and particularly relates to a prestressed structure hole grouting compactness detection method. BACKGROUND

[0002] The post-tensioning method of prestressed construction is widely used in engineering construction. The construction method is to first pour concrete into a component, and pre-leave a hole at the position of the prestressed steel strand in the component. After the concrete reaches the design strength, the prestressed steel strand is inserted into the hole, the steel strand is tensioned, and then the grouting is performed in the hole. The grouting makes the steel strand and the concrete become one, and the air and moisture in the hole are removed, so as to protect the steel strand. Therefore, it is necessary to detect the grouting compactness of the prestressed structure hole.

[0003] The existing prestressed structure hole grouting compactness detection device can be divided into a grouting material flow detection device, an electromagnetic wave detection device, and an ultrasonic wave and stress wave detection device according to the detection principle. The flow monitoring device can only detect the hole grouting condition in the prestressed structure construction process, and cannot detect the built structure. The electromagnetic wave detection device is not sensitive to the concrete structure defects, and cannot detect the grouting compactness of the metal corrugated pipe hole. The compactness detection equipment based on ultrasonic wave or stress wave is widely used, but the commonly used detection equipment is a single channel equipment, the detection efficiency is low, and the signal generated by the excitation equipment is uncontrollable.

[0004] It can be seen that the grouting compactness detection device in the prior art has the problems of low detection efficiency and uncontrollable vibration source signal. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a prestressed structure hole grouting compactness detection system, which solves the problems of low detection efficiency and uncontrollable vibration source signal of the grouting compactness detection device in the prior art.

[0006] According to the embodiment of the present application, a prestressed structure hole grouting density detection system comprises a signal excitation device, a signal acquisition device, a signal conversion and transmission device and a signal receiving, processing and display device; the signal excitation device is connected with the signal conversion and transmission device, used for generating an impact elastic wave at an excitation point of the prestressed structure hole and transmitting the impact elastic wave converted into a first electric signal to the signal conversion and transmission device; the signal acquisition device is connected with the signal conversion and transmission device, used for collecting an impact reflected wave at a collection point of the prestressed structure hole and transmitting the impact reflected wave converted into a second electric signal to the signal conversion and transmission device; wherein the impact reflected wave is a wave reflected by the impact elastic wave after the impact elastic wave is reflected by the prestressed structure hole; wherein the signal acquisition device is a multi-channel acquisition; the signal conversion and transmission device is connected with the signal receiving, processing and display device, used for converting the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively; the signal receiving, processing and display device is used for analyzing the second digital signal to obtain a grouting density detection result of a monitored point on the prestressed structure hole and performing image display on the first digital signal, the second digital signal and the grouting density detection result; wherein the excitation point and the collection point are symmetrical relative to the monitored point.

[0007] Optionally, the signal excitation device is a piezoelectric impact force hammer, which comprises a hammer body, a buffer hammer head and a pressure sensor; the hammer body comprises a hammer handle and a hammer head, the hammer handle is inserted into a groove provided in the hammer head; the buffer hammer head is sleeved on a first end of the pressure sensor, used for adjusting the impact pressure signal frequency; a second end of the pressure sensor is arranged at a first end of the hammer head, used for converting the impact elastic wave into an electric signal in proportion.

[0008] Optionally, the piezoelectric impact force hammer further comprises an additional hammer head arranged at a second end of the hammer head, used for adjusting the mass of the piezoelectric impact force hammer.

[0009] Optionally, the signal acquisition device is a plurality of piezoelectric acceleration sensors, which comprise a support layer, a diaphragm layer and a piezoelectric film layer arranged in sequence; the support layer has a window, the window exposes part of the diaphragm layer, so that part of the diaphragm layer is suspended; when the impact reflected wave is collected, the suspended diaphragm layer deforms, the deformation of the diaphragm layer drives the piezoelectric film layer to deform; the surfaces of the piezoelectric film layer away from and towards the diaphragm layer are respectively provided with upper and lower electrodes, used for transmitting the second electric signal generated by the deformation of the piezoelectric film layer.

[0010] Optionally, the signal conversion and transmission device comprises a data acquisition card, and the data acquisition card comprises a multi-channel A / D conversion module configured to convert the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively.

[0011] Optionally, the signal conversion and transmission device further comprises a mobile power supply and a package, wherein the mobile power supply is configured to supply power to the signal excitation device, the signal acquisition device and the signal conversion and transmission device, and the package is configured to install the data acquisition card and the mobile power supply inside the package, and has a state indicating lamp, a data input interface and a data output interface outside the package, and the state indicating lamp is configured to indicate a working state of the device.

[0012] In another aspect, according to the embodiment of the present application, a prestressed structure hole grouting density detection method is also provided, which uses any of the above-mentioned systems and comprises the following steps: the signal excitation device generates an impact elastic wave at an excitation point of the prestressed structure hole, and converts the impact elastic wave into a first electric signal; the signal acquisition device acquires an impact reflected wave at an acquisition point of the prestressed structure hole, and converts the impact reflected wave into a second electric signal; the signal receiving, processing and display device converts the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively; the signal receiving, processing and display device analyzes the second digital signal to obtain a grouting density detection result of a monitored point on the prestressed structure hole, and displays images of the first digital signal, the second digital signal and the grouting density detection result; and the excitation point and the acquisition point are symmetrical relative to the monitored point.

[0013] Optionally, the signal acquisition device acquires the impact reflected wave at the acquisition point of the prestressed structure hole, which comprises triggering the signal acquisition device to acquire the impact reflected wave at the acquisition point of the prestressed structure hole according to the impact elastic wave.

[0014] Optionally, the signal receiving, processing and display device analyzes the second digital signal to obtain the grouting density detection result of the monitored point on the prestressed structure hole, which comprises: grouping the second digital signals belonging to the same monitored point into a two-dimensional data matrix , wherein is an amplitude, is a distance between the signal excitation point and the sampling point, denoted as a detection distance, is a sampling time; performing one-dimensional frequency domain low-pass filtering on the common center point sampling data to form a one-dimensional filtered data matrix , wherein is a one-dimensional filtered signal amplitude, is the vibration detection distance, is the sampling time; the one-dimensional filter data is filtered in two-dimensional frequency domain to form a two-dimensional filter data matrix , the two-dimensional filter data matrix is two-dimensional filter data, wherein, is the two-dimensional filter signal amplitude, is the vibration detection distance, is the sampling time; the two-dimensional filter data is converted into a superimposed acceleration spectrum , wherein, is the superimposed amplitude, is the reflection time, is the superimposed acceleration; the superimposed acceleration spectrum is divided into n energy groups on the time axis, and the peak value of each energy group is calculated and the reflection time ; wherein n is a positive integer, 0<n<4; the superimposed acceleration and the reflection time are converted into the layer velocity and the layer depth of the nth reflection layer; wherein the lower the layer velocity, the lower the density.

[0015] The technical principle of the present application is that the signal excitation device generates an impact elastic wave at the excitation point of the prestressed structure hole, the signal collection device collects the impact reflected wave at the collection point of the prestressed structure hole, and then the signal conversion and transmission device converts the digital signal and transmits it to the signal receiving, processing and display device, the signal receiving, processing and display device performs digital signal processing and analysis on the digital signal, analyzes the signal characteristics of the impact reflected wave, obtains the compaction density of the monitored point on the prestressed structure hole, and performs image display, and the excitation point and the collection point are symmetrical relative to the monitored point.

[0016] Compared with the prior art, the present application has the following beneficial effects: by using the signal excitation device to generate an impact elastic wave at the excitation point of the prestressed structure hole, and analyzing the signal characteristics of the impact reflected wave at the symmetrical position relative to the monitored point, the compaction density of the monitored point in the prestressed structure hole is determined, which solves the technical problems of low detection efficiency of the compaction density detection device and uncontrollable vibration source signal in the prior art, and the signal collection device generates a technical effect of improving the detection efficiency of the compaction density detection device, and the signal excitation device converts the impact elastic wave into an electrical signal, generating a technical effect of controllable vibration source signal. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a prestressed structure hole compaction density detection system diagram of an embodiment of the present application;

[0018] Figure 2 is a piezoelectric impact force hammer structure diagram of another embodiment of the present application;

[0019] Figure 3 The signal conversion transmission device structure diagram of another embodiment of the present application;

[0020] Figure 4 The prestressed structure hole grouting density detection method of the embodiment of the present application;

[0021] Figure 5 The signal waveform diagram generated by the piezoelectric impact force hammer of the embodiment of the present application;

[0022] Figure 6 The signal waveform diagram collected by the piezoelectric acceleration sensor of the embodiment of the present application;

[0023] Figure 7 The original group diagram of the time sequence signal waveform group composed of the impact reflection wave of the same monitored point of the embodiment of the present application;

[0024] Figure 8 The one-dimensional filter diagram of the time sequence signal waveform group composed of the impact reflection wave of the same monitored point of the embodiment of the present application;

[0025] Figure 9 The two-dimensional filter diagram of the time sequence signal waveform group composed of the impact reflection wave of the same monitored point of the embodiment of the present application;

[0026] Figure 10 The two-dimensional image of the grouting density detection result of the embodiment of the present application;

[0027] Figure 11 The three-dimensional image of the grouting density detection result of the embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the present application will be further described below in combination with the drawings and embodiments.

[0029] As Figure 1As shown, the embodiment of the present application provides a prestressed structure hole grouting density detection system, which comprises a signal excitation device 100, a signal collection device 200, a signal conversion and transmission device 300 and a signal receiving, processing and display device 400; the signal excitation device 100 is connected with the signal conversion and transmission device 300, used for generating an impact elastic wave at an excitation point of the prestressed structure hole and transmitting the impact elastic wave converted into a first electric signal to the signal conversion and transmission device; the signal collection device 200 is connected with the signal conversion and transmission device 300, used for collecting an impact reflected wave at a collection point of the prestressed structure hole and transmitting the impact reflected wave converted into a second electric signal to the signal conversion and transmission device 300; wherein the impact reflected wave is a wave reflected by the impact elastic wave after the impact elastic wave is reflected by the prestressed structure hole; wherein the signal collection device is a multi-channel collection; the signal conversion and transmission device 300 is connected with the signal receiving, processing and display device 400, used for converting the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively; the signal receiving, processing and display device 400 is used for analyzing the second digital signal to obtain a grouting density detection result of a monitored point on the prestressed structure hole, and performing image display on the first digital signal, the second digital signal and the grouting density detection result; wherein the excitation point and the collection point are symmetrical relative to the monitored point.

[0030] The detailed working process of the embodiment is as follows: the signal excitation device 100 generates an impact elastic wave at an excitation point of the prestressed structure hole, selects a monitored point, and the impact elastic wave meets an impact reflected wave reflected by a defect in the prestressed structure hole, i.e. a place with poor grouting density, under the monitored point, and the signal characteristics of the impact reflected wave reflected by other positions under the monitored point are different, because the depths of the defect and the other positions are different, the reflection distances are also different, several groups of excitation points and collection points symmetrical relative to the monitored point can be selected at the same monitored point, the signal collection device 200 collects the impact reflected wave at a collection point of the prestressed structure hole, and then transmits the digital signal converted by the signal conversion and transmission device 300 to the signal receiving, processing and display device 400, the signal receiving, processing and display device 400 performs digital signal processing analysis on the digital signal, obtains the grouting density of the monitored point on the prestressed structure hole by analyzing the signal characteristics of the impact reflected wave, and performs image display. The multi-channel collection by the signal collection device can improve the detection efficiency of the grouting density detection device, and the impact elastic wave converted into an electric signal by the signal excitation device can control the vibration source signal.

[0031] As Figure 2As shown, according to another embodiment of the present application, the signal excitation device 100 is a piezoelectric impact hammer, wherein the piezoelectric impact hammer comprises a hammer body, a buffer hammer head 4 and a pressure sensor 3; the hammer body comprises a hammer handle 2 and a hammer head 1, the hammer handle 2 is inserted into the groove provided on the hammer head 1; the buffer hammer head 4 is sleeved on the first end of the pressure sensor 3, for adjusting the impact pressure signal frequency; the second end of the pressure sensor 3 is provided on the first end of the hammer head 1, for converting the impact elastic wave into an electric signal in proportion.

[0032] The detailed working process of the embodiment is as follows: holding the hammer handle 2 to drive the hammer head 1 to contact the buffer hammer head 4 with the prestressed structure hole side excitation point for knocking, to generate an impact elastic wave, the pressure generated by the buffer hammer head 4 is reversely applied to the pressure sensor 3, so that the pressure sensor 3 converts the impact pressure into an electric signal in proportion, and the pressure sensor 3 transmits the electric signal to the signal conversion and transmission device 300. Since the piezoelectric impact hammer is provided with the pressure sensor, the impact elastic wave is converted into an electric signal in proportion, and the effect of controllable vibration source signal is generated.

[0033] In some embodiments, the buffer hammer head 4 has a series of models and materials, for adjusting the signal frequency, and the signal frequency is adjusted to adapt to different detection objects.

[0034] Preferably, the piezoelectric impact hammer further comprises an additional hammer head 5 provided on the second end of the hammer head 1, for adjusting the mass of the piezoelectric impact hammer. The additional hammer head has a series of models and weights, for adjusting the mass of the hammer, so that the signal amplitude of the impact elastic wave can be changed by adjusting the mass of the hammer through the additional hammer head.

[0035] Optionally, the signal collection device 200 is a plurality of piezoelectric acceleration sensors, the piezoelectric acceleration sensor comprises a support layer, a diaphragm layer and a piezoelectric film layer arranged in sequence, the support layer has a window, the window exposes part of the diaphragm layer, so that part of the diaphragm layer is suspended, when the reflected shock wave is collected, the suspended diaphragm layer deforms, the deformation of the diaphragm layer drives the piezoelectric film layer to deform, and the piezoelectric film layer is provided with an upper electrode and a lower electrode on the surfaces opposite to the diaphragm layer, so as to transmit the second electric signal generated by the deformation of the piezoelectric film layer. In this way, by using the piezoelectric acceleration sensor, the collected reflected shock wave can be converted into an electric signal and transmitted to the signal conversion and transmission device 300. By using the plurality of piezoelectric acceleration sensors for multi-channel collection, a plurality of monitored points can be selected at the same time, when one excitation point is selected, the collection points are selected at positions opposite to the monitored points relative to the excitation point, the signal collection device collects at the collection points, another excitation point is selected, and the collection points are selected in the same way for collection, each collection is simultaneous collection of the reflected shock waves of a plurality of monitored points, and after multiple collections, a plurality of reflected shock waves of a plurality of monitored points can be collected. In this way, compared with the prior art in which only one collection point is used in each single channel, and the reflected shock wave of the same monitored point can be collected after multiple collections, the detection efficiency is improved by using the multi-channel collection method.

[0036] Optionally, the signal conversion and transmission device 300 comprises a data collection card, the data collection card comprises a multi-channel A / D conversion module, and the multi-channel A / D conversion module is used to convert the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively. In this way, the analog signal received by the signal conversion and transmission device can be converted into a digital signal for easy analysis.

[0037] In some embodiments, the data collection card has a multi-channel A / D conversion module, a data buffer module and a data transmission module, the multi-channel A / D conversion module converts the analog signal transmitted by the signal excitation device and the signal collection device into a digital signal, buffers the digital signal in the data buffer module, and transmits the digital signal to the signal receiving, processing and display device 400 through the data transmission module.

[0038] As shown in Figure 3 According to another embodiment of the present application, the signal conversion and transmission device 300 further comprises a mobile power supply 303 and a packaging 302; the mobile power supply 303 is used to supply power to the signal excitation device 100, the signal collection device 200 and the signal conversion and transmission device 300; the packaging 302 is used to install the data collection card 301 and the mobile power supply 303 inside, and has a state indicating lamp, a data input interface and a data output interface outside; and the state indicating lamp is used to indicate the working state of the device.

[0039] The detailed working process of the embodiment is as follows: the data acquisition card 301 collects the first electric signal and the second electric signal transmitted by the signal exciting device 100 and the signal collecting device 200, and converts them into corresponding digital signals, at the same time, the mobile power supply 303 is connected with the signal exciting device 100, the signal collecting device 200 and the signal conversion and transmission device 300 through the external through holes of the packaging 302 and supplies power for them, the independent power supply time is greater than 10 hours, the packaging 302 is equivalent to an outer shell, the data acquisition card 301 and the mobile power supply 303 are installed in the outer shell, and the state indicating lamp, the data input interface and the data output interface are arranged outside the packaging 302 and connected with the data acquisition card 301 through the external through holes. The state indicating lamp is used to indicate the working state of the device, for example, the state indicating lamp is bright when the data is collected, and is off when no signal is collected. In this way, the mobile power supply is adopted to make the device more convenient to charge and more portable, and the state indicating lamp outside the packaging makes the working state of the device be monitored, which is convenient for detection.

[0040] As shown in Figure 4 In another aspect, the embodiment of the present application also provides a prestressed structure hole grouting density detection method, which comprises the following steps:

[0041] S401, the signal exciting device generates an impact elastic wave at an exciting point of the prestressed structure hole, and converts the impact elastic wave into a first electric signal.

[0042] S402, the signal collecting device collects an impact reflected wave at a collecting point of the prestressed structure hole, and converts the impact reflected wave into a second electric signal.

[0043] S403, the signal receiving and processing display device converts the first electric signal and the second electric signal into a first digital signal and a second digital signal, respectively.

[0044] S404, the signal receiving and processing display device analyzes the second digital signal to obtain a grouting density detection result of a monitored point on the prestressed structure hole, and displays images of the first digital signal, the second digital signal and the grouting density detection result; wherein the exciting point and the collecting point are symmetrical relative to the monitored point.

[0045] The prestressed structure hole pressure grouting density detection method provided by the embodiment of the present disclosure is used to generate an impact elastic wave at an exciting point of the prestressed structure hole through a signal exciting device, collect an impact reflected wave at a collection point of the prestressed structure hole through a signal collecting device, and then convert the impact reflected wave into a digital signal through a signal conversion and transmission device and transmit the digital signal to a signal receiving, processing and display device. The signal receiving, processing and display device performs digital signal processing and analysis on the digital signal, obtains the pressure grouting density condition of a monitored point on the prestressed structure hole by analyzing the signal characteristics of the impact reflected wave, and performs image display. The exciting point and the collection point are symmetrical relative to the monitored point. The signal collecting device is used to collect the impact reflected wave through multiple channels, thereby improving the detection efficiency of the pressure grouting density detection device, and the signal exciting device is used to convert the impact elastic wave into an electrical signal, thereby achieving controllable vibration source signals.

[0046] Optionally, the signal collecting device collects the impact reflected wave at the collection point of the prestressed structure hole, including collecting the impact reflected wave at the collection point of the prestressed structure hole according to the impact elastic wave as a trigger signal. The impact elastic wave is used as a trigger signal, and the signal collecting device collects data at the same time when the signal exciting device generates the impact elastic wave, so as to realize synchronization of excitation and collection. In this way, the time experienced by the impact elastic wave from excitation to collection, i.e., the signal first wave propagation time, can be obtained. If the excitation and the collection are not synchronized, the signal first wave propagation time cannot be obtained, and the signal first wave propagation time is beneficial to subsequent signal analysis.

[0047] Optionally, the signal receiving, processing and display device analyzes the second digital signal to obtain a pressure grouting density detection result of the monitored point on the prestressed structure hole, including: grouping the second digital signals belonging to the same monitored point into a two-dimensional data matrix , the two-dimensional data matrix is denoted as common center point sampling data, wherein, is an amplitude, is a distance between the signal exciting point and the sampling point and is denoted as a vibration detection distance, is a sampling time; performing one-dimensional frequency domain low-pass filtering on the common center point sampling data to form a one-dimensional filtered data matrix , the one-dimensional filtered data matrix is denoted as one-dimensional filtered data, wherein, is a one-dimensional filtered signal amplitude, is the vibration detection distance, is the sampling time; performing two-dimensional frequency domain filtering on the one-dimensional filtered data to form a two-dimensional filtered data matrix , the two-dimensional filtered data matrix is two-dimensional filtered data, wherein, is a two-dimensional filtered signal amplitude, is the vibration detection distance, is the sampling time; and converting the two-dimensional filtered data into a superimposed acceleration spectrum. wherein, is the superimposed amplitude, is the reflection time, is the superimposed velocity; divided into n energy groups on the superimposed velocity spectrum time axis, and the peak value of each energy group is calculated and the reflection time ; wherein n is a positive integer, 0 < n < 4; the superimposed velocity and the reflection time are converted into the layer velocity and the layer depth of the nth reflection layer; wherein the lower the layer velocity, the lower the density.

[0048] In some embodiments, the digital signal converted by the signal conversion device from the impact elastic wave generated by the piezoelectric impact force hammer is directly displayed as a signal waveform by the signal receiving and processing display device, as shown in Figure 5 , and the digital signal of the impact reflection wave collected by the piezoelectric acceleration sensor is directly displayed as a signal waveform, as shown in Figure 6 , and signal feature analysis can be performed, i.e., software automatic analysis of the signal first wave propagation time, signal amplitude, and signal frequency. Alternatively, the digital signal is processed and analyzed by a specific imaging calculation and processing algorithm of the present application, as shown in Figure 7 , the impact reflection waves of the same monitored point are grouped to form a time sequence signal waveform diagram, the vertical coordinate represents the propagation time, and the horizontal coordinate represents the sampling channel, i.e., the signals collected by different collection points. At the same time, the second digital signal belonging to the same monitored point is grouped to form a two-dimensional data matrix , and the two-dimensional data matrix is denoted as the common center point sampling data, wherein, is the amplitude, is the distance between the signal excitation point and the sampling point, denoted as the vibration detection distance, is the sampling time. As shown in Figure 8 , the common center point sampling data is subjected to one-dimensional frequency domain low-pass filtering to form a one-dimensional filtered data matrix , and the one-dimensional filtered data matrix is denoted as one-dimensional filtered data, wherein, is the one-dimensional filtered signal amplitude, is the vibration detection distance, is the sampling time. As shown in Figure 9 , the one-dimensional filtered data is subjected to two-dimensional frequency domain filtering to form a two-dimensional filtered data matrix , and the two-dimensional filtered data matrix is denoted as two-dimensional filtered data, wherein, is the two-dimensional filtered signal amplitude, is the vibration detection distance, is the sampling time. The two-dimensional filtered data is converted into a superimposed velocity spectrum , wherein, is a superimposed amplitude, is a reflection time, is a superimposed velocity; dividing the superimposed velocity spectrum time axis into n energy groups, respectively calculating the peak value of each energy group corresponding to the superimposed velocity and the reflection time ; wherein n is a positive integer, 0 < n < 4; converting the superimposed velocity and the reflection time into the layer velocity and the layer depth of the n th reflection layer; using interpolation processing to insert the layer velocity value at other positions, performing two-dimensional image display as shown in Figure 10 , judging the compaction degree according to the color depth, i.e. the gray value, of the image; the lighter the color, the smaller the gray value, the smaller the layer velocity value, i.e. the wave velocity value, and the lower the compaction degree. Three-dimensional image display can also be performed through interpolation, as shown in Figure 11 , the color above the image is the color corresponding to the wave velocity of the surcharge layer, the lighter the color, the lower the wave velocity and the lower the compaction degree. In this way, combined with the unique digital signal processing module and the imaging algorithm calculation processing module, the hole surcharge compaction degree detection is realized, with high detection precision, and the detection result is intuitive and accurate through two-dimensional and three-dimensional image display.

[0049] In some embodiments, the signal receiving processing display device is a mobile computer.

[0050] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method for detecting the density of a pre-stressed structural duct grout, characterized in that, The method comprises the following steps: The signal excitation device generates an impact elastic wave at an excitation point of the prestressed structure hole, and converts the impact elastic wave into a first electrical signal; The signal collection device collects an impact reflected wave at a collection point of the prestressed structure hole, and converts the impact reflected wave into a second electrical signal; wherein the impact reflected wave is a wave reflected by the impact elastic wave after passing through the prestressed structure hole; wherein the signal collection device is a multi-channel collection; a plurality of piezoelectric acceleration sensors are arranged to perform multi-channel collection and simultaneously monitor a plurality of monitored points; when an excitation point is selected, a collection point is selected at a position symmetrical to the excitation point relative to each monitored point, and the signal collection device synchronously collects the impact reflected wave of the plurality of monitored points at each collection point; then another excitation point is selected, the corresponding collection point is selected in the same way, and collection is performed; after a plurality of collections, a plurality of impact reflected wave data of each monitored point are obtained; The signal conversion and transmission device converts the first electrical signal and the second electrical signal into a first digital signal and a second digital signal, respectively; The signal receiving, processing and displaying device analyzes the second digital signal to obtain a compaction degree detection result of the monitored point on the prestressed structure hole, and displays images of the first digital signal, the second digital signal and the compaction degree detection result, wherein the excitation point and the collection point are symmetrical to the monitored point; The signal excitation device is connected to the signal conversion and transmission device, and is used to transmit the first electrical signal converted from the impact elastic wave to the signal conversion and transmission device; The signal collection device is connected to the signal conversion and transmission device, and is used to transmit the second electrical signal converted from the impact reflected wave to the signal conversion and transmission device; The signal conversion and transmission device is connected to the signal receiving, processing and displaying device.

2. The method for detecting the pressure grouting density of a pre-stressed structural duct according to claim 1, characterized in that, The signal excitation device is a piezoelectric impact hammer, which comprises a hammer body, a buffer hammer head and a pressure sensor; The hammer body comprises a hammer handle and a hammer head, and the hammer handle is inserted into a groove provided in the hammer head; The buffer hammer head is sleeved on a first end of the pressure sensor, and is used to adjust the impact pressure signal frequency; A second end of the pressure sensor is arranged at a first end of the hammer head, and is used to convert the impact elastic wave into an electrical signal in a proportional manner.

3. A method of detecting the density of the pressure grouting in a prestressed structure hole according to claim 2, characterized in that, The piezoelectric impact hammer further comprises an additional hammer head arranged at a second end of the hammer head, and used to adjust the mass of the piezoelectric impact hammer.

4. The method of claim 1, wherein the method further comprises: The signal acquisition device is a plurality of piezoelectric acceleration sensors, the piezoelectric acceleration sensor comprises a support layer, a diaphragm layer and a piezoelectric film layer arranged in sequence, the support layer has a window, the window exposes part of the diaphragm layer, so that part of the diaphragm layer is suspended, when the reflected wave of the impact is collected, the suspended diaphragm layer deforms, the deformation of the diaphragm layer drives the deformation of the piezoelectric film layer, the piezoelectric film layer is provided with an upper electrode and a lower electrode on the surface away from and towards the diaphragm layer respectively, and the upper electrode and the lower electrode are respectively connected with a cable wire to transmit the second electric signal generated by the deformation of the piezoelectric film layer to the signal conversion and transmission device.

5. The method of claim 1, wherein the method further comprises: The signal conversion and transmission device comprises a data acquisition card, and the data acquisition card comprises a multi-channel A / D conversion module, which is used for converting the first electric signal and the second electric signal into a first digital signal and a second digital signal respectively.

6. A method of detecting the density of the pressure grouting in a prestressed structural duct according to claim 5, characterized in that, The signal conversion and transmission device further comprises a mobile power supply and a package; The mobile power supply is used for supplying power to the signal excitation device, the signal acquisition device and the signal conversion and transmission device; The package is used for mounting the data acquisition card and the mobile power supply inside, and has a state indicating lamp, a data input interface and a data output interface outside; wherein the state indicating lamp is used for indicating the working state of the device.

7. A method for detecting the density of the pressure grouting in a pre-stressed structural duct as claimed in claim 1, wherein The signal receiving, processing and displaying device analyzes the second digital signal to obtain the compaction degree detection result of the monitored point on the prestressed structure hole, comprising: The second digital signals belonging to the same monitored point are combined into a two-dimensional data matrix The two-dimensional data matrix is denoted as common center point sampling data, wherein, is an amplitude, is a distance between a signal excitation point and a sampling point, denoted as a vibration detection distance, is a sampling time; The common center point sampling data is subjected to one-dimensional frequency domain low-pass filtering to form a one-dimensional filtered data matrix The one-dimensional filtered data matrix is denoted as one-dimensional filtered data, wherein, is a one-dimensional filtered signal amplitude, is a vibration detection distance, is a sampling time; performing two-dimensional frequency filtering on the one-dimensional filtered data to form a two-dimensional filtered data matrix , the two-dimensional filtered data matrix being two-dimensional filtered data, wherein, is a two-dimensional filtered signal amplitude, is a range, is a sampling time; Converting two-dimensional filtered data to stacked velocity spectra wherein, is the stacked amplitude, is the reflection time, is the stacked velocity; The superimposed acceleration spectrum time axis is divided into n energy groups, and the peak values of each energy group are calculated and reflection time ; wherein, n is a positive integer, 0<n<4; Converting the superimposed velocities and reflection times to layer depths of the nth reflection layer and layer depths ; wherein lower layer velocities indicate lower compactness.

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