A method for detecting the paving thickness of an asphalt pavement

Abstract

The present invention discloses a method for detecting the paving thickness of an asphalt pavement, which relates to the field of municipal transportation and includes: First, send a first radar signal to the road surface and collect the radar echo signal A i and the reception duration t i , and determine the initial primary echo signal; Then, according to the determined primary echo signal B j , solve the reflectivity R of the jth medium interface j , solve the dielectric constant ε of the (j + 1)th medium layer j+1 , solve the layer thickness H of the jth medium layer j ; Finally, obtain the radar echo signal A for which it is not determined whether it is a primary echo signal i , and judge whether the radar echo signal A i matches the secondary echo signals of each determined primary echo signal B j . If so, solve the secondary echo estimation value, and use the radar echo signal A i and the secondary echo estimation value as the newly added primary echo signal B j+1 . The present invention can effectively measure the thickness of the asphalt pavement, and the thickness solving accuracy is high.

Description

Technical Field

[0001] The present invention relates to the field of municipal transportation, and particularly to a method for detecting the paving thickness of asphalt pavement. Background Art

[0002] In the early stage, the thickness of road surfaces was generally detected by the method of core sampling. This method is relatively traditional. When taking core samples on road surfaces, it is not only somewhat dangerous during sampling, but also easily damages the road surface structure after sampling, easily destroying the integrity and aesthetics of the road surface structure layer, and has quite large limitations.

[0003] Ground penetrating radar is a new type of detection device, which has gradually been taken seriously and widely applied in the practical application of road engineering. The working principle of ground penetrating radar is to emit high-frequency electromagnetic waves downward from the road surface, and the received antenna receives the electromagnetic waves returning to the road surface. The electromagnetic waves penetrate different dielectric layers underground, and infer the spatial state and structural form of the medium based on the characteristics of the waveform and amplitude change of the received electromagnetic waves with an electrical difference. Finally, the detected road surface thickness and the deflection data of the road surface are obtained. Ground penetrating radar uses its high resolution and fast detection speed, which integrates high-end advanced technologies such as modern electronic technology, information technology, and electromagnetic technology, to detect the road surface to be detected, and has been widely used in many practical projects and achieved good results. It reflects high standards of fast, effective, and non-destructive in the process of highway detection, and is very suitable for detecting road surface parameters and related rut diseases during the construction period and operation management period of asphalt highways.

[0004] The reflection coefficient method is a commonly used method for detecting the thickness of road surfaces. However, in the prior art, the measurement accuracy of this method is often inaccurate and needs to be corrected. Summary of the Invention

[0005] In view of a part of the defects of the prior art, that is, when the traditional reflection coefficient method is used to detect the road thickness, when considering the refraction and reflection of the radar emission signal, it does not consider that the radar signal will be reflected multiple times in the road and the secondary echo signal caused by the multiple reflections will be regarded as the primary echo signal and substituted into the solution of the reflectivity of the dielectric layer and the measurement of the road surface thickness, resulting in inaccurate overall measurement data. In view of this, the technical problem to be solved by the present invention is to provide a device for detecting the paving thickness of asphalt pavement, aiming to analyze whether the radar echo signal is a primary echo signal or a secondary echo signal, eliminate the secondary echo signal, solve the reflectivity of each dielectric interface through the primary echo signal, and further solve to obtain the accurate road surface thickness.

[0006] To achieve the above object, the present invention provides a method for detecting the paving thickness of asphalt pavement, and the method includes:

[0007] Step S1: Send a first radar signal to the road surface and collect each radar echo signal A i And each radar echo signal A i Relative to the reception time t of the first radar signal i ; The initial amplitude of the first radar signal is A 0 ; i is the echo number of the radar echo signal, i=1, 2, ..., n, and n is the current maximum value of the echo number; the radar echo signal A i Including one echo signal B j and a secondary echo signal; the primary echo signal B j is the radar echo signal A obtained by transmitting the first radar signal through the asphalt road surface until it is reflected at the jth medium interface and directly transmits out of the asphalt road surface. i ; Wherein, the round trip period of each of the dielectric layers is T j , The j=1, ..., m, wherein m is the current maximum number of the primary echo signal; is the primary echo signal B j Relative to the reception time of the first radar signal; wherein, B 0 =A 1 , B 1 =A 2 , T 1 =t 2 -t 1 ;

[0008] Step S2: according to the determined primary echo signal B j , solve the reflectivity R of the jth medium interface j , execute step S3; wherein the reflectivity R j is the reflectivity of the medium interface between the air layer and the road surface,

[0009] Step S3: According to the reflectivity R j and the dielectric constant ε of the jth dielectric layer j , solve the dielectric constant ε of the j+1th dielectric layer j+1 , execute step S4; wherein, the ε 0 is the dielectric constant of the air layer;

[0010] Step S4: According to the round trip period of the dielectric layer being T j , the dielectric constant ε of the j-th dielectric layer j , solve the thickness H of the jth dielectric layer j, execute step S5; where the layer thickness where c is the speed of light;

[0011] Step S5, obtain the radar echo signal A that is not determined whether it is the primary echo signal i , determine the radar echo signal A i whether it matches the secondary echo signals of each determined primary echo signal B j If so, solve the estimated value of the secondary echo, and use the difference between the radar echo signal A i and the estimated value of the secondary echo as the newly added primary echo signal B j+1 ; return to execute step S2.

[0012] In this technical solution, by using the improved reflection coefficient method to solve the thickness of the road surface, its accuracy is higher than that of the prior art; among them, according to the round-trip period of each dielectric layer, in terms of time, it is judged whether the radar echo signal is likely to be a secondary echo signal formed by the round-trip reflection of a known primary echo signal in the dielectric layer, and further whether the numerical value of the secondary echo signal matches. When it does not match, the radar signal can be subtracted from the estimated value of the secondary echo signal to obtain the corresponding primary echo signal; overall, using the improved reflection coefficient method can eliminate the influence of the secondary echo signal on the road surface thickness detection and improve the road surface detection accuracy.

[0013] In a specific embodiment, the step S5 includes:

[0014] Step S51, obtain the radar echo signal A that is not determined whether it is the primary echo signal i , according to each determined primary echo signal B j and the round-trip period T j , judge whether there is such that the reception duration t i of the radar echo signal A i can satisfy: where the the K (x,j) represents the number of round-trip reflections of the radar echo signal A i in the jth layer of the dielectric layer; each item of {K (x,1) ,...,K (x,j) ,...,K (x,m)} is a non-negative integer and at least one item is a positive integer;

[0015] Step S52, if the is not satisfied, then increase the radar echo signal A that is not determined whether it is the primary echo signal i to the primary echo signal Bj+1 , determine the first echo signal B j+1 relative to the reception duration of the first radar signal determine the round-trip period of the dielectric layer of the (j + 1)-th layer Return to execute step S2;

[0016] Step S53, if the is satisfied, then obtain the that satisfies the corresponding first echo signal B x , solve the estimated value of the second echo If the radar echo signal A whose identity as the first echo signal is undetermined i matches the , it is the second echo signal; otherwise, increase the first echo signal determine the first echo signal B j+1 relative to the reception duration of the first radar signal determine the round-trip period of the dielectric layer of the (j + 1)-th layer Return to execute step S2; wherein, the the

[0017] In a specific embodiment, if there are multiple groups such that t i satisfies: the estimated value of the second echo is the sum of multiple groups after calculation.

[0018] In a specific embodiment, in step S53, when the then it is considered that the radar echo signal A i matches the ; 1 ≤ α ≤ 1.05.

[0019] In a specific embodiment, the method further includes: generating a cross-sectional thickness structure of the asphalt pavement according to the layer thickness H of each dielectric layer j .

[0020] In a specific embodiment, the method further includes: obtaining the thickness of the asphalt pavement according to the layer thickness H of each dielectric layer j , dielectric constant ε j and the preset range of the asphalt pavement.

[0021] The beneficial effects of the present invention are as follows: By using an improved reflection coefficient method to solve the thickness of the road surface, the present invention has higher accuracy compared with the prior art. Among them, according to the round-trip period of each medium layer, it is judged in terms of time whether the radar echo signal has the possibility of being a secondary echo signal formed by the round-trip reflection of a known primary echo signal in the medium layer, and further estimate whether the value of the secondary echo signal matches. When it does not match, the radar signal can be deducted from the estimated value of the secondary echo signal to obtain the corresponding primary echo signal. Generally speaking, the improved reflection coefficient method can eliminate the influence of the secondary echo signal on the road surface thickness detection and improve the road surface detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flowchart of a method for detecting the paving thickness of an asphalt road surface provided in a specific embodiment of the present invention;

[0023] Figure 2 is a radar propagation path diagram of a method for detecting the paving thickness of an asphalt road surface provided in a specific embodiment of the present invention;

[0024] Figure 3 is an example diagram of various forms of the same-source secondary echo signal listed in a specific embodiment of the present invention;

[0025] Figure 4 is another radar propagation path diagram of a method for detecting the paving thickness of an asphalt road surface provided in a specific embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be further described below with reference to the drawings and embodiments:

[0027] In the actual process of detecting the thickness of an asphalt road surface, the reflection coefficient method is often used to gradually solve the emissivity, dielectric constant and road surface thickness of the road surface layer by layer. However, in this process, the reflection and refraction of different layers will have a superposition effect, ignoring that the reflection signal may have undergone multiple reflections in a medium layer, resulting in multiple secondary echoes being doped in the radar echo. And in the solution process, these secondary echo signals are regarded as primary echo signals for solution. In this way, the number of road surface layers will be invisibly increased in the actual solution process, and the solution result will have errors or inaccuracies.

[0028] It is worth mentioning that in the present invention, the radar signal is reflected once at the bottom layer and refracted twice in and out of each layer, and the signal received as the radar echo is called the primary echo signal; while the radar echo that has undergone multiple reflections in the medium layer of the road surface is the secondary echo signal.

[0029] Therefore, in the present invention, by eliminating and subtracting the secondary echo signals, a relatively pure primary echo signal is obtained, and the road surface thickness information obtained in this way is also relatively accurate.

[0030] As Figures 1-4 shown, in the first embodiment of the present invention, a method for detecting the paving thickness of an asphalt road surface is provided, and the method includes:

[0031] Step S1: Send a first radar signal to the road surface, and collect each radar echo signal A i and the reception duration t i of each radar echo signal A i relative to the first radar signal; the initial amplitude of the first radar signal is A 0 ; where i is the echo number of the radar echo signal, i = 1, 2,..., n, and n is the current maximum value of the echo number; the radar echo signal A i includes a primary echo signal B j and a secondary echo signal; the primary echo signal B j is the radar echo signal A when the first radar signal transmits through the asphalt road surface until it is reflected at the jth medium interface and directly transmits out of the asphalt road surface i ; where the round-trip period of each medium layer is T j , the j = 1,..., m, and m is the current maximum number of the primary echo signal; the is the reception duration of the primary echo signal B j relative to the first radar signal; where B 0 = A 1 , B 1 = A 2 , T 1 = t 2 -t 1 ;

[0032] Step S2: Solve the reflectivity R j of the jth medium interface according to the determined primary echo signal B j , and execute step S3; where the reflectivity R j is the reflectivity of the medium interface between the air layer and the road surface, the

[0033] Step S3: Solve the dielectric constant ε j of the j + 1th medium layer according to the reflectivity R j and the dielectric constant ε j+1, perform step S4; wherein, the ε 0 is the dielectric constant of the air layer;

[0034] Step S4. According to the round-trip period of the dielectric layer being T j , the dielectric constant ε of the j-th dielectric layer j , solve for the layer thickness H of the j-th dielectric layer j , and perform step S5; wherein, the layer thickness where c is the speed of light;

[0035] Step S5. Obtain the radar echo signal A that is not determined whether it is the primary echo signal i , and determine whether the radar echo signal A i matches the secondary echo signals of each of the determined primary echo signals B j . If so, solve for the secondary echo estimated value, and use the difference between the radar echo signal A i and the secondary echo estimated value as the newly added primary echo signal B j+1 ; return to perform step S2.

[0036] In this embodiment, step S5 includes:

[0037] Step S51. Obtain the radar echo signal A that is not determined whether it is the primary echo signal i , and according to each of the determined primary echo signals B j and the round-trip period T j , determine whether there exists such that the reception duration t of the radar echo signal A i can satisfy: i wherein, the where the K (x,j) represents the number of round-trip reflections of the radar echo signal A i in the j-th dielectric layer; each item of {K (x,1) ,..., K (x,j) ,..., K (x,m)} is a non-negative integer and at least one item is a positive integer;

[0038] Step S52. If the is not satisfied, then add the radar echo signal A that is not determined whether it is the primary echo signal i as the primary echo signal B j+1 , determine the reception duration of the primary echo signal B j+1 relative to the first radar signal determine the round-trip period of the (j + 1)-th dielectric layer Return to execute step S2;

[0039] Step S53, if the is satisfied, then obtain the corresponding primary echo signal B x , and solve the estimated value of the secondary echo If the radar echo signal A, which is not determined whether it is the primary echo signal i matches the , then it is the secondary echo signal; otherwise, increase the primary echo signal Determine the primary echo signal B j+1 relative to the reception duration of the first radar signal Determine the round-trip period of the dielectric layer of the (j + 1)-th layer Return to execute step S2; where the the

[0040] In this embodiment, if there are multiple groups such that t i satisfies: the estimated value of the secondary echo is the sum of multiple groups after operation.

[0041] In this embodiment, in step S53, when the then it is considered that the radar echo signal A i matches the ; 1 ≤ α ≤ 1.05.

[0042] In this embodiment, the method further includes: generating a cross-sectional thickness structure of the asphalt pavement according to the layer thickness H of each dielectric layer j .

[0043] In this embodiment, the method further includes: obtaining the thickness of the asphalt pavement according to the layer thickness H of each dielectric layer j , the dielectric constant ε j and the preset range of the asphalt pavement.

[0044] It is worth mentioning that in the figure, for the sake of simplicity of illustration and to avoid clutter of lines, the angular relationship between the incident angle and the refraction angle is not considered, and the line segments where the incident angle and the refraction angle are located are directly represented by straight lines; moreover, in practical applications, the detection radar is approximately vertically incident, and the angular difference between the incident angle and the refraction angle is so small that it can be approximately ignored; in addition, if the incident ray is directly perpendicular to the road surface, at this time the reflected ray coincides directly with the incident ray, which is not conducive to the explanation of this application, so the oblique incidence is used for illustration instead.

[0045] As Figure 2 shown, there are a total of 10 groups of data (A 1 -A 10 ) in the current radar echo signal. Among them, A 1 , A 2 , A 4 , A 7 are primary echo signals, which are respectively denoted as B 0 , B 1 , B 2 , B 3 ; A 3 , A 5 , A 8 , A 9 are the secondary echoes of B 1 ; A 6 is the secondary echo of the superposition of B 1 and B 2 ; A 10 is the secondary echo of B 2 .

[0046] The relevant formulas in the present invention will be derived and explained below.

[0047] As Figure 2 shown, according to the optical properties, it can be obtained that:

[0048] That is, B 0 = A 0 R 0 ;

[0049] Similarly, A 0 (1 - R 0 )R 1 (1 + R 0 ) = B 1 ;

[0050] A 0 (1 - R 0 )(1 - R 1 )R 2 (1 + R 0 )(1 + R 1 ) = B 2 ;

[0051] It can be recursively obtained that the reflectivity

[0052] For the formula its physical meaning is that the echo signal A i the reception time t i and the time difference between the echo signal B x in the previous time is whether it is an integer multiple of the round-trip period T j If so, the echo signal A i may be a secondary echo signal;

[0053] At this time, it is necessary to pass to judge the amplitude of the echo signal A i If the two are equal, the echo signal A i is a pure secondary echo signal. When the two are not equal, the difference between the two is the primary echo signal.

[0054] Among them, Taking an actual case as an example, when it satisfies in terms of time: it means that A i makes two more round trips in the first layer, one more round trip in the second layer, and one more round trip in the third layer; As Figure 3 gives its 12 cases; at this time, the above 12 echo components are actually of the same origin (the same as B x ); while, in other cases, the echo signals may not be of the same origin, such as Figure 4 the case given, A 4 the corresponding echo estimate needs to superimpose and solve these two sets of components, that is,

[0055] The above has described in detail the preferred specific embodiments of the present invention. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the existing technology should be within the protection scope determined by the claims.

Claims

1. A method for detecting the paving thickness of an asphalt pavement, characterized in that, the method includes: Step S1: Send a first radar signal to the road surface and collect each radar echo signal A i and each radar echo signal A i with respect to the reception duration t of the first radar signal i ; the initial amplitude of the first radar signal is A 0 ; where i is the echo number of the radar echo signal, i = 1, 2,..., n, and n is the current maximum value of the echo number; the radar echo signal A i includes a primary echo signal B j and a secondary echo signal; the primary echo signal B j is the radar echo signal A when the first radar signal transmits through the asphalt road surface until it is reflected at the j-th medium interface and directly transmits out of the asphalt road surface i ; where the round-trip period of each medium layer is T j , the j = 1,..., m, and m is the current maximum number of the primary echo signal; the is the reception duration of the primary echo signal B j with respect to the first radar signal; where B 0 = A 1 , B 1 = A 2 , T 1 = t 2 - t 1 ; Step S2: Based on the determined primary echo signal B j , solve for the reflectivity R of the j-th medium interface j , and perform Step S3; where the reflectivity R j is the reflectivity of the medium interface between the air layer and the road surface Step S3: According to the reflectivity R j and the dielectric constant ε of the j-th dielectric layer j , solve for the dielectric constant ε of the (j + 1)-th dielectric layer j+1 , and perform Step S4; where the ε 0 is the dielectric constant of the air layer; Step S4: According to the round-trip period of the dielectric layer being T j , the permittivity ε of the j-th dielectric layer j , solve for the layer thickness H of the j-th dielectric layer j , and perform step S5; where the layer thickness where c is the speed of light; Step S5: Obtain the radar echo signal A whose identity as the primary echo signal is undetermined i , and determine whether the radar echo signal A i matches the secondary echo signals of each of the determined primary echo signals B j . If so, solve the estimated value of the secondary echo; if the radar echo signal A i matches the estimated value of the secondary echo, it is the secondary echo signal; otherwise, use the difference between the radar echo signal A i and the estimated value of the secondary echo as the newly added primary echo signal B j+1 ; determine the reception duration of the primary echo signal B j+1 relative to the first radar signal Determine the round-trip period of the dielectric layer of the (j + 1)-th layer Return to step S2 for execution.

2. The method for detecting the paving thickness of an asphalt pavement according to claim 1, characterized in that, the step S5 includes: Step S51: Obtain the radar echo signal A whose status as the primary echo signal is undetermined i , and based on each determined primary echo signal B j and the round-trip period T j , determine whether there exists such that the reception duration t i of the radar echo signal A i can satisfy: where the K( x,j ) represents the number of round-trip reflections of the radar echo signal A i in the dielectric layer of the j-th layer; each item of {K( x,1 ),..., K( x,j ),..., K( x,m )} is a non-negative integer and at least one item is a positive integer; Step S52. If the following is not satisfied then increase the radar echo signal A that is not determined to be the first echo signal i to be the first echo signal B j+1 , determine the first echo signal B j+1 with respect to the reception duration of the first radar signal determine the round-trip period of the dielectric layer of the (j + 1)-th layer return to execute Step S2; Step S53, if the is satisfied, then obtain the corresponding first echo signal B x , and solve the estimated value of the second echo If the radar echo signal A whose identity as the first echo signal is undetermined i matches the , then it is the second echo signal; otherwise, increase the first echo signal Determine the reception duration of the first echo signal B j+1 relative to the first radar signal Determine the round-trip period of the dielectric layer of the (j + 1)-th layer Return to execute Step S2; where the the 3. The method for detecting the paving thickness of an asphalt pavement according to claim 2, characterized in that, If there are multiple groups such that t i satisfies: The estimated value of the second echo is the sum of multiple groups after operation.

4. The method for detecting the paving thickness of an asphalt pavement according to claim 2 or 3, characterized in that, In the step S53, when it is considered that the radar echo signal A i matches with the ; 1 ≤ α ≤ 1.

05.

5. The method for detecting the paving thickness of an asphalt pavement according to claim 1, characterized in that, The method further includes: generating a profile thickness structure of the asphalt pavement according to the layer thickness H of each of the dielectric layers j , 6. The method for detecting the paving thickness of an asphalt pavement according to claim 1, characterized in that, The method further includes: obtaining the thickness of the asphalt pavement according to the layer thickness H of each of the dielectric layers j , the dielectric constant ε j and the preset range of the asphalt pavement

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