KR101116879B1 - The apparatus and method of detecting a impact file in zigbee communication - Google Patents
The apparatus and method of detecting a impact file in zigbee communication Download PDFInfo
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Abstract
The present invention is a method for checking the soundness of the existing impact pile is a "detection method" consisting of visual inspection, Parallel Sonic Loggong and Parallel Seismic Logging, or Impact Echo method (Impact Echo) It is composed of the "undetected hole test method" consisting of the impact response method (Impact Resonse) and there is no standard fault classification algorithm, so it is impossible to check the defect state of the impact pile accurately in real time, and the two-way data transmission wirelessly In order to solve the problem of difficult 1: 1 defect pile detection, it is composed of sensor unit with DSP processor, Zigbee communication unit, and data logger unit with defect classification algorithm, so it is measured between sensor unit and data logger through Zigbee communication network. Data and impact pile fault detection parameters can be transmitted and received in both directions Safer measurement in impossible places and above all, the preset defect classification algorithm enables real-time detection of 1: 1 customized concrete pile defects, improving impact pile damage and defect rate by 90%. It is an object of the present invention to provide a defect detection apparatus and method for impact piles through a defect classification algorithm consisting of a total response time, a number of peaks, and a sign of a peak.
Description
According to the present invention, the method of checking the integrity of impact piles includes a visual inspection, a "detection hole method" consisting of Parallel Sonic Loggong and Parallel Seismic Logging, or an Impact Echo method. The present invention relates to a defect detection device and method for impact piles using a ZigBee communication-based defect classification algorithm that can be compatible with an "undetected hole test method" consisting of an impact response method (Impact Resonse).
In general, as the society develops and becomes more advanced, huge structures such as buildings and bridges continue to increase. In addition, the method of supporting the huge building is to be built on a foundation pile that is hard and deeply embedded on the rocky surface of the sea floor and the ground so that it does not fall down against strong winds and heavy impacts. Therefore, it is very important that these piles be constructed to support the design load.
By the way, when the foundation pile is driven, the driving is applied with a large impact by driving, in which case the concrete pile is stuck while being damaged and damage is caused by the large impact of the driving, or the pile is disconnected by foreign substances in the ground, Since it is not in contact with the rock and is in the ground, it is not possible to withstand the heavy loads of high-rise buildings and huge bridges, and the buildings and bridges are often tilted or collapsed, so whether the piles are damaged or whether the piles are in contact with the ground It was inevitable that evaluation had to be made.
In evaluating the piles, conventionally, excavations around piles or structures were examined and the presence or absence of damages were examined by eyes. This method can be directly identified and judged by eyes, but large-scale excavation is required. There are many problems in direct excavation due to the enormous amount of time and money mobilized with manpower.
In addition, there is a method of checking the length of the pile by receiving the waveform by hitting the same hammer and generating a waveform by the first method, but this method measures only the speed of the elastic waves coming from the same medium with one geophone. Since only the length could be measured, there was a limit in investigating the reduction of the cross section of the pile itself and the major defects such as the tip of the pile.
In addition, there is a third method of boring the concrete pile to the core and measuring the concrete pile by the inclinometer and the displacement of the surroundings and checking the abnormality. This method also requires a lot of boring to find the defect on the opposite side. There was a problem that required time and money.
Finally, there is a method of investigating the quality of huge piles by ultrasonic by embedding PVC pipe inside the cast-in-place pile. This method has the advantage of accurately evaluating the quality of the pile, but it is applied only to large-diameter cast-in-place piles. Produced and driven piles and foundation plates had a problem that can not be investigated.
In order to solve such a problem, in Korean Patent Laid-Open Publication No. 10-2004-0052961 (published on June 23, 2004), (a) a step of generating a signal by hitting the head of a pile with a hammer (S100); (b) transmitting data received from the plurality of geophones disposed at different angles to the acoustic wave and the impedance generated when the hammer is hit in the step (a); (c) combining and analyzing the velocity and impedance of the acoustic wave based on the elastic wave and the impedance transmitted in the step (b) to process and transmit the shape, the quality state and the result of the irradiation object according to the velocity result of the elastic wave in the main body ( S300); And (d) the step of processing the body processing data received in the step (c) to be displayed on the image display unit (S400); non-destructive inspection method of the construction site piles, but was presented,
This is because there is no standard defect classification algorithm, and various types of defects are presented according to the types of defect detection devices for skilled workers and impact piles, which causes only confusion of field work and cannot confirm the exact condition of impact piles. There was this.
In addition, since the operator must directly connect the measuring equipment by wire to an inaccessible place such as a huge structure and the bottom of a bridge, the installation time and measurement time are long, and above all, the system is configured to measure only one-way measurement data. As a result, 1: 1 customized concrete pile defect data could not be accurately provided for various types of impact pile defects.
In order to solve the above problems, the present invention can transmit and receive measurement data and impact pile defect detection values between the sensor unit and the data logger through the Zigbee communication network in both directions, so that the measurement can be safely performed even in an inaccessible place. In addition, it is possible to provide a defect classification algorithm compatible with the existing shock echo tester, and above all, the preset defect classification algorithm can detect 1: 1 customized concrete pile defects in real time, thus damaging the impact pile. The purpose of the present invention is to provide a defect detection device and method for impact piles through a defect classification algorithm consisting of a sign of total response time, number of peaks, and peaks, which can improve the presence and defect rate compared to the existing ones.
In order to achieve the above object, a defect detection device for an impact pile through a defect classification algorithm based on the ZigBee communication according to the present invention is
It consists of a defect detection device for impact piles (1) for measuring the defect and strength of the impact pile used to support the bridge or building,
The defect detection device (1) for the impact pile
It is installed on one side of the impact pile, measures the echo signal of the shock wave applied from the impact pile from the hammer, wirelessly transmits the measured data to the data logger located at a short distance, and receives the parameter value for impact pile defect detection from the data logger. Receiving
Located 5m ~ 20m away from the sensor, the noise received by the measured data transmitted from the sensor is removed, and defects of impact piles are detected through the fault classification algorithm consisting of the total response time, number of peaks, and the code of the peak. And a
In addition, the defect detection method for impact piles through the ZigBee communication-based defect classification algorithm according to the present invention
Transmitting the impact pile defect detection parameter values relating to the impact pile length, the defect detection start / stop signal, and the velocity of the shock wave from the data logger to the sensor unit through the ZigBee communication network (S100);
An acceleration sensor is operated according to a defect detection start command of the data logger to measure an echo signal of the shock wave when a shock wave is applied from the impact pile at the hammer (S200);
Wirelessly transmitting the measured data measured by the acceleration sensor to a data logger located at a short distance through a Zigbee communication network (S300);
Removing, by the data filtering unit of the data logger unit, a signal including a noise component of the digital data signal through a wavelet packet transform (S400);
In the impact pile defect detection unit, a defect classification algorithm including a total response time, a number of peaks, and a code of a peak is detected, thereby detecting the defect of the impact pile (S500).
As described above, in the present invention, it is possible to measure more safely even in an inaccessible place, and can provide a defect classification algorithm compatible with an existing impact echo test apparatus, and above all, through a preset defect classification algorithm. : 1 Customized concrete pile defects can be detected in real time, which has a good effect of improving the impact pile damage rate and defect rate by 90%.
1 is a block diagram showing the components of a defect detection device for impact piles through a ZigBee communication-based defect classification algorithm according to the present invention,
Figure 2 is a block diagram showing the components of the data logger of the defect detection device for impact piles through the Zigbee communication-based defect classification algorithm according to the present invention,
Figure 3 is an embodiment showing the operation of the data logger of the defect detection device for impact piles through the ZigBee communication-based defect classification algorithm according to the present invention,
Figure 4 is an embodiment showing the impact echo method for measuring the stress-wave propagation (Stress-wave propagation) of the pile-ground system by the transient vibration load acting in the impact pile axial direction according to the present invention through the acceleration sensor Ye
5 is a block diagram illustrating components of an n-level WPT tree according to the present invention;
6 is a diagram illustrating a graph in which noise is removed by applying WPT according to the present invention;
7 is a graph showing a signal waveform consisting of the sign of the total response time-peak number-peak according to the present invention;
8 is an embodiment showing one impact pile in a steady state and seven impact piles having a defect;
9 is a graph showing the response signal obtained by generating a seismic wave of 4000 m / s in eight impact piles according to the present invention
FIG. 10 is a graph illustrating a signal obtained by filtering the original signal of FIG. 9 using WPT; FIG.
11 is a view illustrating a process of first classifying detailed defects of impact piles by comparing the total response time with the response time in a steady state according to the present invention and analyzing the number of detected peaks;
Figure 12 is an embodiment showing the classification of the defects of the impact pile after first classifying the detailed defects of the impact pile according to the present invention,
FIG. 13 is a diagram illustrating a process of second classifying detailed defects of an impact pile by analyzing a sign of a detected peak according to the present invention; FIG.
14 is a flowchart illustrating a defect detection method for impact piles through a Zigbee communication-based defect classification algorithm according to the present invention;
FIG. 15 is a flowchart illustrating a process of detecting a defect of an impact pile through a defect classification algorithm comprising an overall response time, a number of peaks, and a code of a peak in an impact pile defect detection unit according to the present invention; FIG.
First, the fault detection device for the impact pile through the fault classification algorithm consisting of the total response time, the number of peaks, and the peak code according to the present invention is measured by using the principle of the impact echo technique before applying the programmed defect classification algorithm. do.
The impact echo technique refers to a technique of measuring stress-wave propagation of a pile-ground system by a transient vibration load acting in an impact pile axial direction through an acceleration sensor of a sensor unit.
As shown in FIG. 4, the compressed wave generated by the impact of the hammer propagates into the pile, is reflected by a defect or another boundary surface, and returns to the pile head.
That is, the stress wave generated in the upper part meets the interface of the discontinuous surface or other medium, part of the wave energy is reflected and returned to the original medium, and the other is transmitted to the other medium.
These stress wave reflection / transmission characteristics are characterized by the difference in the acoustic wave impedance (Acoustic Impedance) between the two media (
Therefore, in the present invention, the depth L of the reflection wave generating portion (= length to the crack and the defective reflection source) is defined and measured as shown in
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
1 is a configuration diagram showing the components of the defect detection device for impact piles through a defect classification algorithm consisting of the total response time-number of peaks-the sign of the peak according to the present invention, which is the impact pile (10), The
The
The hammer strikes the head of the
Next, the
The
It is composed of any one selected from inertial, gyro and silicon semiconductor.
The
In other words, by checking the position continuously with a certain time period, the difference in position when the shock wave is moved from the head of the impact pile to the internal defect site (cracking damage).
The DSP (Digital Signal)
In addition, the
That is, since the signals output from the acceleration sensor and the position sensor are output in an analog form such as 4-20 mA or 0-5 V, the analog signals are converted into digital signals.
The first
This is a first Zigbee communication transmission unit for wirelessly transmitting the measurement data to the data logger unit located near,
And a first ZigBee communication receiving unit for receiving the impact pile defect detection parameter value from the data logger unit.
ZigBee refers to a low power wireless short-range standard communication technology. It is best suited for low cost, very low power consumption, small size and program, fast speed at short distance, and rare network usage.
Low power consumption, transfer rate is up to 250 Kbps in 2.4GHz band, and the chip is very inexpensive enough to be used for more than one year even with a typical battery.
Up to 65,536 nodes can be attached to the network, and even star, cluster tree and mesh network networks are supported. Based on the IEEE 802.15.4 PHY and MAC standards, the ZigBee alliance (such as companies and research institutes) was centered and the ZigBee specification of the upper layer network and application layer was established.
By using the features of the Zigbee communication, the present invention is configured to be connected to the sensor unit and the data logger unit located within 5 ~ 20m to the Zigbee communication module.
The
The
In addition, the sensor unit according to the present invention is a magnetic portion is configured on the bottom portion in contact with the impact pile.
That is, since the magnetic part is formed in the bottom part of a sensor part, when a shock reflection signal is measured, a sensor part can be supported in a fixed position so that it may not be shaken by external pressure.
Next, the
The
In the present invention, it is assumed that the configuration is a personal computer.
As illustrated in FIG. 2, the
The
Here, the wavelet packet transform refers to a technique of interpreting a signal by analyzing the signal into rough approximations and details in different frequency bands having a plurality of resolutions.
That is, wavelet packet conversion may be a method of decomposing data, a function, or operators into different frequency components, and examining each component associated with a resolution corresponding to each scale.
The fundamental principle of wavelet packet conversion is similar to Fourier analysis, and wavelet packet conversion can be used for signal processing to recover weak signals mixed in noise.
However, wavelets have a narrow window in the high frequency band and a wide window in the low frequency band, compared to Fourier, which uses the same sized filter for all frequency bands.
Images processed in this way can be processed cleanly without blurring details.
In addition, the wavelet packet transformation is suitable for image processing because it reflects the fact that when a person looks at an object, the overall outline is first identified and the focus is gradually focused on details.
The basic operation of the wavelet packet conversion is applied to a discrete signal having n samples. A pair of filters are applied to the signal to separate the low and high frequency bands. Each band is subsampled with an element of 2, so it contains n / 2 samples.
In other words, the original signal is filtered using a highpass filter and a lowpass filter, and then downsampled to decompose the data and divided into approximate and detailed information. The coefficient is a signal passing through a highpass filter and can be viewed as a noise component.
5 is a block diagram showing the components of the n-Level WPT Tree according to the present invention.
In addition, FIG. 5 relates to a graph comparing the normal response signal according to the present invention with the result of 2-level WPT. The WPT approximation coefficient signal is displayed in red and the original signal is displayed in blue.
That is, as shown in Figure 5, it can be confirmed that the noise component has been removed, it can be seen that the characteristics of the original signal can be represented as it is through the decomposed approximation signal.
In addition, WPT conversion reduces the number of data, which reduces the time calculated for defect classification.
The impact
The defect classification algorithm removes the noise component of the measured data transmitted from the sensor unit by applying WPT, and then, based on the sign of the total response time, number of peaks, and peak of one impact pile in a steady state, This is a programmatic extraction of one defect classification table compared to the seven impact piles in the neck, including burrs with low foreign matter.
Here, as shown in FIG. 8, if there are eight impact piles, the defect classification criteria table may be classified into eight types as shown in Table 1 by applying a defect classification algorithm.
(Number of peaks)
(Sign of peak)
As shown in FIG. 7, the total response time T is generated by the impact wave generated from the hammer to the pier of the impact pile from the point where the impact wave is generated from the bottom of the impact pile. Say the time to come back.
As shown in FIG. 7, the number N of peaks is when a shock wave is started or when a shock wave is in contact with a medium different from one of the signal waveforms responding from the bottom of the impact pile from the point of occurrence of the shock wave, or a neck or a buggy. The number of peaks protruding convexly when a defect such as a burke or a crack occurs.
As shown in FIG. 7, the peak sign is expressed as "-" when the ongoing shock wave comes in contact with the high density among the signal waveforms responding from the bottom of the impact pile from the point of occurrence of the shock wave. When the signal is expressed as "+".
The second
Hereinafter, a defect detection method for impact piles through a Zigbee communication-based defect classification algorithm according to the present invention will be described in detail.
First, as shown in FIG. 14, the impact pile defect detection parameter values of the impact pile length, the defect detection start / stop signal, and the speed of the shock wave are transmitted from the data logger unit to the sensor unit through the ZigBee communication network (S100). .
Subsequently, the acceleration sensor is operated according to the defect detection start command of the data logger to measure the echo signal of the shock wave when the shock wave is applied from the impact pile by the hammer (S200).
Subsequently, the measured data measured by the acceleration sensor is wirelessly transmitted to the data logger located at a short distance through the Zigbee communication network (S300).
Subsequently, the data filtering unit of the data logger unit removes a signal including a noise component of the digital data signal through a wavelet packet transform (S400).
Subsequently, the impact pile defect detection unit detects a defect of the impact pile through a defect classification algorithm consisting of a sign of total response time, number of peaks, and peak (S500).
As shown in FIG. 15, in the state in which noise is removed through a wavelet packet transform, detecting the number of peaks among the signal waveforms responded from the bottom of the impact pile from the point of generating the shock wave (S510). )Wow,
Measuring a time response T at the bottom of the impact pile from the point of occurrence of the shock wave in the signal waveform (S520),
Detecting a sign of a peak among the signal waveforms (S530);
Comparing the total response time with the response time in a steady state, and analyzing the number of detected peaks to first classify the detailed defects of the impact pile (S540);
Analyzing the sign of the detected peak to secondary classification of the detailed defects of the impact pile (S550) is included.
[Detecting the number of peaks among the signal waveforms responding from the bottom of the impact pile from the point where the shock wave is generated while the noise is removed through the wavelet packet transform]
First, a shock wave is generated by using a hammer to classify defects, and a response signal is measured by using a speed (acceleration) sensor installed at the top of the pile.
In order to remove noise of the measured signal, the WPT is applied to the measuring apparatus, and the number of peaks is detected by using the signal from which the noise is removed.
The number of peaks of the response signal is generated evenly, and two peak signals are generated in the case of a normal impact pile in which the minimum number of peaks is generated (a peak at the point of impact wave generation and the response signal to the bottom).
After detecting the number of peaks, if the number of peaks is less than 2 or an odd number is detected, an error code is generated. Otherwise, the next step is performed.
[Step of measuring the response time (T) from the bottom of the impact pile to the point of impact wave generation of the signal waveform]
If the peak detection step proceeds without error, the next step is to measure the overall response time (T).
The overall response time of the shock wave to the concrete pile is shorter when the internal density of the concrete pile is higher and longer when the density is lower. Therefore, the defects of the pile can be measured in comparison with the overall response time of the impact pile in the steady state. have.
That is, if the total measured response time is longer than the response time for the impact pile in the steady state, it may be determined that the material of the pile is low in density or in the middle of the foreign material, and the density of the foreign material is low.
In addition, there may be a change in appearance in addition to the inclusion of foreign matter (classified as the case of A illustrated in FIG. 11). On the contrary, if the response time for the impact pile in the steady state is shorter, it may be determined that the density of the constituent material of the pile is high or the foreign material is caught in the middle, and the density of the foreign material is high.
Also in this case, there may be a cosmetic deformation (classified as the case of C shown in FIG. 11). That is, in the case of concrete piles, the higher the density, the better the quality.
If the response time of the impact pile in the steady state and the response time of the file to detect the current defect is almost the same, it can be classified as a impact pile in the steady state or a file with a change in appearance (B of FIG. 11). Classified as cases).
Table 2 below shows the relationship between the quality of concrete piles, shock wave speed, internal strength and modulus of elasticity.
(MPa)
[Step of detecting peak sign among signal waveforms]
It detects the sign of the peak as "-" when the shock wave in progress during the entire response time T of the signal waveform is in contact with the high density, and detects the sign of the peak as "+" when in contact with the low density.
[Comparing the total response time with the response time in the steady state, analyzing the number of detected peaks and first classifying the detailed defects of the impact pile]
① In case of A of FIG. 11, the overall response time T of the impact pile to be measured is shorter than the response time Tr of the impact pile in a steady state. It can be considered that there is a dense foreign substance in the middle.
In order to classify this, the number of peaks is detected, and may be classified as <D1> as follows according to the number of peaks.
<D1>
When the number of peaks is two, it is classified as the case of the impact pile (the peak detected at the beginning and the end) with a high density.
When the number of peaks exceeds two, 1) the overall density is classified as including a defect such as a neck or burge, or 2) a dense foreign material is included in the middle, or a neck Or a defect such as a burge.
② In case of C of FIG. 11, the overall response time (T) of the impact pile to be measured is longer than the response time (Tr) of the impact pile in a steady state. It can be considered that there is a dense foreign substance in the middle.
In order to classify this, the number of peaks is detected, and may be classified as <D3> as follows according to the number of peaks.
<D3>
When the number of peaks is two, it is classified as a case of impact piles (peaks detected at the beginning and the end) of low density.
When there are more than two peaks, 1) the overall density is low, and a defect such as a neck or burge is included, or 2) a low density foreign material is included in the middle, or a neck Or as including a defect such as a burge.
③ In case of B of FIG. 11, the overall response time (T) of the impact pile to be measured is almost the same as the response time (Tr) of the impact pile in a steady state. In other words, it can be considered to include defects such as cosmetic changes in the middle.
In this case, the number of peaks is detected for more detailed classification as described above, and may be classified as <B2> according to the number of peaks.
<B2>
When the number of peaks is two, they are classified into the same shape as in the case of a normal impact pile.
If the number of peaks is greater than two, it is classified as including a neck or a burge.
[Secondly classifying the detailed defects of the impact pile by analyzing the sign of the detected peak]
The sign of the peak according to the present invention is detected in the form of +,-when a high density foreign material is contained in the impact pile, and is detected in the order of-, + when a low density foreign material is included.
Also, in case of appearance defects, the neck is detected in the order of-, +, and in the case of the burge, it is detected in the order of +,-.
Therefore, the classification is based on these characteristics.
That is, FIG. 12 relates to a flowchart in which D1, D2, and D3, which primarily classify the detailed defects of the impact pile by analyzing the number of detected peaks, are subdivided according to the sign of the peak.
<Segmentation according to the sign of the peak at D1>
For example, when the number of peaks is analyzed and the primary classification of the detailed defects of the impact pile is D1, it is checked how many times the sign of the-and + forms is included (case 1).
1) Contains N foreign matter layers of low density.
2) Overall high density, containing N times of neck defects.
3) Contains a low density of foreign material layers and neck defects.
As another example, the number of peaks is analyzed to check how many times the +/- sign is included when the first classification of the detailed defects of the impact pile includes D1 (case 2).
1) Contains N density of foreign matter layers.
2) Overall, high density, containing N times Burger defects.
3) Contains a dense layer of foreign matter and burglary defects.
As another example, when the number of peaks is analyzed to first classify the detailed defects of the impact pile, the number of (+,-) and (-, +) forms of signs is included (case 3). do.
1) Contain N high density and low foreign matter layers.
2) The density is high overall and includes N times of burge and neck.
3) Includes a dense layer of foreign matter and neck defects N times.
4) Contains N dense foreign material layers and burr defects N times.
<Segmentation according to the sign of the peak at D2>
For example, when the number of peaks is analyzed and the first classification of the detailed defects of the impact pile is D2, it is checked how many times the sign of the-and + forms is included (case 1).
1) Contains N foreign matter layers of low density.
2) Overall high density, containing N times of neck defects.
3) Contains a low density of foreign material layers and neck defects.
As another example, the number of peaks is analyzed to check how many times the +/- sign is included when the first classification of the detailed defects of the impact pile includes D2 (case 2).
1) Contains N density of foreign matter layers.
2) Overall, high density, containing N times Burger defects.
3) Contains a dense layer of foreign matter and burglary defects.
In another example, when the number of peaks is analyzed to first classify the detailed defects of the impact pile, the number of times (+,-) and (-, +) forms both of the signs in the case of D2 is checked (case 3). do.
1) Contain N high density and low foreign matter layers.
2) The density is high overall and includes N times of burge and neck.
3) Includes a dense layer of foreign matter and neck defects N times.
4) Contains N dense foreign material layers and burr defects N times.
<Segmentation according to the sign of the peak at D3>
For example, when the number of peaks is analyzed and the primary classification of the detailed defects of the impact pile is D3, it is checked how many times the sign of the-and + forms is included (case 1).
1) Contains N foreign matter layers of low density.
2) Overall high density, containing N times of neck defects.
3) Contains a low density of foreign material layers and neck defects.
As another example, the number of peaks is analyzed to check how many times the +/- sign is included when the first classification of the detailed defects of the impact pile includes D3 (case 2).
1) Contains N density of foreign matter layers.
2) Overall, high density, containing N times Burger defects.
3) Contains a dense layer of foreign matter and burglary defects.
As another example, when the number of peaks is analyzed to first classify the detailed defects of the impact pile, the number of (+,-) and (-, +) forms of signs are included in case of D3 (case 3). do.
1) Contain N high density and low foreign matter layers.
2) The density is high overall and includes N times of burge and neck.
3) Includes a dense layer of foreign matter and neck defects N times.
4) Contains N dense foreign material layers and burr defects N times.
Hereinafter, the defect detection method for the impact pile through the defect classification algorithm consisting of the total response time, the number of peaks and the sign of the peak according to the present invention will be described in detail.
For example, as shown in FIG. 8, simulation data for eight impact piles is generated, and these defects for impact piles are detected through a defect classification algorithm.
In FIG. 8, CASE A shows a normal impact pile, CASE B shows a case where a foreign substance having a low density is included once, and CASE C shows a case where a foreign substance having a low density has been contained twice, and CASE D represents a case where the neck is included once, CASE E represents a case where the burges are included once, and CASE F includes a single substance having a low density and a single neck. In this case, CASE G is a case where a low-density foreign material is included and a burge is included once, and CASE H is a case where a neck and a berge are included once.
9 is a graph illustrating a response signal obtained by generating a 4000 m / s elastic wave in the file, and FIG. 10 is a graph illustrating a signal obtained by filtering the original signal of FIG. 9 using WPT.
For the feature extraction, first, two thresholds th1 and th2 are set to find peak values greater than th1 or less than th2.
The portions indicated by red circles in FIG. 10 are peak values found using two threshold values.
Referring to the characteristics of each case using the detected peak data, the defect classification criteria table may be generated by applying the defect classification algorithm as shown in Table 1 described above.
When the defects of the eight impact piles shown in FIG. 8 are classified using the characteristic values described in the defect classification criteria table as shown in Table 1 as follows. However, in the normal state, the total time of Normal is 4.7 ~ 4.8.
[Case A]: Case A is classified as the case of B because the total time is almost the same as the signal for the impact pile in the steady state, and the number of peaks is 2, so that B-
[Case B]: Case B is classified as C because the total time is longer than that of the normal file, and since the number of peaks exceeds 2 and includes the-and + signs once, C-
[Case C]: Case C is classified as C because the total time is longer than that of the normal impact pile, and the number of peaks exceeds 2, and the remaining peak values except the starting peak value and the ending peak value are-, Since the + sign is included twice, it can be classified as C-
[Case D]: Case D is a case in which the total time is the same as the total time for the normal signal, the number of peaks is greater than 2, and the B-
[Case E]: Case E may be classified as B-
[Case F]: Case F is shown in FIG. 8 because the total time is increased and the peak value is 6, and the signs of the remaining peak values except for the starting peak value and the ending peak value are-, +,-, +. Can be classified as C-
[Case G]: Case G is shown in FIG. 8 because the total time is increased and the peak value is 6, and the signs of the remaining peak values except for the starting peak value and the ending peak value are-, +, +,-. Can be classified as C-
[Case H]: Case H can be classified as B-
10: impact pile 100: sensor unit
110: acceleration sensor 120: position sensor
130: DSP processor 140: the first Zigbee communication module
150
200: data logger 210: A / D converter
220: data filtering unit 230: impact pile defect detection unit
240: second Zigbee communication module
Claims (5)
The defect detection device (1) for the impact pile
It is installed on one side of the impact pile, measures the echo signal of the shock wave applied from the impact pile from the hammer, wirelessly transmits the measured data to the data logger located at a short distance, and receives the parameter value for impact pile defect detection from the data logger. Receiving sensor unit 100,
Located 5m ~ 20m away from the sensor, the noise received by the measured data transmitted from the sensor is removed, and defects of impact piles are detected through the fault classification algorithm consisting of the total response time, number of peaks, and the code of the peak. ZigBee communication base comprising a data logger 200 for transmitting the impact pile defect detection parameter values related to the impact pile length to be measured by the sensor unit, the defect detection start / stop signal, and the velocity of the shock wave. Defect detection device for impact piles through defect classification algorithm.
An acceleration sensor 110 for measuring the acceleration of the shock wave applied from the impact pile in the hammer,
Position sensor 120 is located on one side of the acceleration sensor to measure the displacement of the shock wave applied from the impact pile in the hammer,
It is located on the top of the acceleration sensor and operates the acceleration sensor according to the fault detection start command of the data logger to detect the starting point of the shock wave, and then starts from the point of the shock wave through the length information of the impact pile and the speed information of the impact pile stored in the memory. DSP processor 130 for measuring the data for the estimated arrival time of the reflected signal reflected from the bottom of the impact pile and transmits the measurement data to the data logger through the wireless communication when the measurement is completed,
A first ZigBee communication module 140 positioned at an upper end of the DSP processor and performing wireless communication through a data logger and a ZigBee communication network;
A memory unit 150 for receiving and storing impact pile defect detection parameter values relating to the impact pile length transmitted from the data logger unit, the defect detection start / stop signal, and the velocity of the shock wave;
Impact detection device for impact piles through a fault classification algorithm based on the Zigbee communication, characterized in that consisting of a power supply unit 160 for supplying power to each device through a battery.
The data logger 200
A data filtering unit 210 for removing a signal including a noise component among the digital data signals transmitted from the sensor unit through a wavelet packet transform;
An impact pile defect detection unit 220 for detecting defects of the impact pile through a defect classification algorithm consisting of a total response time, a number of peaks, and a code of a peak,
The defect detection device for the impact pile through the ZigBee communication-based fault classification algorithm, characterized in that comprises a second ZigBee communication module 230 for wireless communication through the sensor unit and the ZigBee communication network.
An acceleration sensor is operated according to a defect detection start command of the data logger to measure an echo signal of the shock wave when a shock wave is applied from the impact pile at the hammer (S200);
Wirelessly transmitting the measured data measured by the acceleration sensor to a data logger located at a short distance through a Zigbee communication network (S300);
Removing, by the data filtering unit of the data logger unit, a signal including a noise component of the digital data signal through a wavelet packet transform (S400);
Impact through defect classification algorithm based on the ZigBee communication, characterized in that the impact pile detection step (S500) through the defect classification algorithm consisting of the total response time, the number of peaks and the sign of the peak in the impact pile defect detection unit Defect detection method for piles.
Detecting the number of peaks among the signal waveforms responding from the bottom of the impact pile from the point where the shock wave is generated in the state where the noise is removed through the wavelet packet transform (S510);
Measuring a time response T at the bottom of the impact pile from the point of occurrence of the shock wave in the signal waveform (S520),
Detecting a sign of a peak among the signal waveforms (S530);
Comparing the total response time with the response time in a steady state, and analyzing the number of detected peaks to first classify the detailed defects of the impact pile (S540);
And analyzing the sign of the detected peak to classify the detailed defects of the impact piles (S550). 2.
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| KR1020100008706A KR101116879B1 (en) | 2010-01-29 | 2010-01-29 | The apparatus and method of detecting a impact file in zigbee communication |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008039594A (en) | 2006-08-07 | 2008-02-21 | Yamaguchi Univ | Crack detection method for concrete foundation pile |
| JP2008507925A (en) | 2004-07-23 | 2008-03-13 | スマート・ストラクチャーズ・インコーポレーテッド | Concrete pile monitoring system and installation method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2008507925A (en) | 2004-07-23 | 2008-03-13 | スマート・ストラクチャーズ・インコーポレーテッド | Concrete pile monitoring system and installation method |
| JP2008039594A (en) | 2006-08-07 | 2008-02-21 | Yamaguchi Univ | Crack detection method for concrete foundation pile |
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