Asphalt mixture compaction density detection method, system and readable storage medium based on interdigital coplanar capacitance

Abstract

The present invention relates to a method, system, and readable storage medium for detecting the compaction density of asphalt mixtures based on interdigitated coplanar capacitance. The detection method comprises the following steps: S1, establishing a relationship between the dielectric constant and capacitance value of an asphalt mixture based on conformal mapping technology and partial capacitance technology; S2, establishing a relationship between the dielectric constant and compaction density of an asphalt mixture based on a dielectric mixing model; S3, performing capacitance measurements on the asphalt mixture domain and the air domain to obtain corresponding capacitance measurement values; S4, correcting the capacitance measurement values ​​in the asphalt mixture domain to be measured based on parasitic capacitance; S5, substituting the corrected capacitance measurement values ​​in S4 into the relationship established in S1 and S2 to obtain the compaction density of the asphalt mixture to be measured. Compared with the prior art, the present invention can be used to detect the compaction density of asphalt mixtures, providing a basis for evaluating the construction quality of asphalt mixtures.

Description

Technical Field

[0001] The present invention belongs to the technical field of urban traffic road engineering construction, and relates to a method, system and readable storage medium for detecting the compaction density of asphalt mixture based on interdigital coplanar capacitance. Background Art

[0002] Asphalt mixture is an important paving material in asphalt pavement, used on the pavement surface to resist traffic loads and environmental impacts. The compaction density of asphalt mixture is a key control criterion for evaluating the construction quality of asphalt pavement. Over-compaction or under-compaction will lead to increased or decreased density, which will deteriorate the performance of the asphalt pavement and induce potential pavement diseases such as segregation, cracking and rutting. Therefore, it is necessary to ensure that the asphalt mixture reaches the ideal density during the construction process. Currently, the methods for measuring the density of asphalt mixture mainly include the surface dry method, CoreLok method, wax seal method and volume method. These methods have high accuracy, but they are all based on on-site core samples, so they can only cover a limited detection area. In addition, coring is a destructive detection method, which will affect normal traffic operations and damage the structural integrity of the asphalt pavement.

[0003] Nondestructive testing methods have attracted widespread attention due to their ability to conduct large-scale, continuous measurements and protect existing pavement structures. Currently, the main nondestructive testing methods used for asphalt mixture density measurement include non-nuclear densitometers, infrared thermal imaging, and ground-penetrating radar (GPR). Non-nuclear densitometers are considered the standardized NDT method for measuring asphalt mixture density in the United States. However, this method is inefficient, requiring a certain response time for each measurement and calibration with a plate of known density. Infrared thermal imaging is also used to measure asphalt mixture density, but its accuracy is unstable due to the diversity of mixture types and paving methods. Ground-penetrating radar (GPR) allows for continuous and large-scale measurements, but relies on the reflection and reception of electromagnetic signals, making it susceptible to environmental influences. Therefore, GPR's measurement accuracy depends primarily on sophisticated signal processing techniques.

[0004] The coplanar capacitance method is a nondestructive testing technique based on electric field principles that can measure the dielectric properties of materials and further obtain other physical information, including density. Previous research has successfully applied this method to measure invisible defects in asphalt mixtures, demonstrating its potential in pavement engineering. However, research on the application of the coplanar capacitance method to measure the compacted density of asphalt mixtures is very limited, and no relevant literature has been found. Summary of the Invention

[0005] The purpose of the present invention is to provide a method, system and readable storage medium for detecting the compaction density of asphalt mixture based on interdigital coplanar capacitance, so as to obtain a more accurate distribution of the compaction density of asphalt mixture through parasitic capacitance elimination method based on the theoretical relationship between the detection capacitance value and the compaction density of asphalt mixture, thereby providing a basis for the quality control and evaluation of asphalt pavement construction.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] In a first aspect, the present invention provides a method for detecting the compaction density of asphalt mixture based on interdigital coplanar capacitance, comprising the following steps:

[0008] S1. Establishing the relationship between the dielectric constant and capacitance value of asphalt mixture based on conformal mapping technology and partial capacitance technology;

[0009] S2. Establish the relationship between the dielectric constant and compaction density of asphalt mixture based on the dielectric mixing model;

[0010] S3. Perform capacitance measurement on the asphalt mixture domain and the air domain to be measured, and obtain corresponding capacitance measurement values;

[0011] S4. Correcting the capacitance measurement value in the asphalt mixture domain under test based on the parasitic capacitance;

[0012] S5. Substitute the corrected capacitance measurement value in S4 into the relationship established in S1 and S2 to obtain the compacted density of the asphalt mixture being measured.

[0013] Furthermore, the process of establishing the relationship in S1 is:

[0014] S11. Based on symmetry, the total capacitance of the interdigital coplanar structure is divided into the upper and lower planes of the electrode for solution. The total capacitance of the upper or lower plane of the electrode is further decomposed into internal capacitance and external capacitance.

[0015] S12. Based on the partial capacitance technique, the internal capacitance and the external capacitance are further decomposed into the internal and external geometric capacitances of each dielectric layer under test;

[0016] S13, obtaining internal and external geometric capacitances using geometric parameters of the interdigital coplanar capacitance sensor and the dielectric constant of the measured dielectric layer according to the commonality mapping technology;

[0017] S14. Establish a theoretical relationship between the dielectric constant of asphalt mixture and the detection capacitance value.

[0018] Furthermore, the relationship between the dielectric constant and capacitance of asphalt mixture is expressed as:

[0019]

[0020] Where C total is the total capacitance, C lower is the total capacitance of the plane under the electrode, C upper is the total capacitance of the electrode plane, C I，lower is the internal capacitance of the plane under the electrode, C E，lower is the external capacitance of the plane under the electrode, C I，upper is the internal capacitance of the plane on the electrode, C E,upper is the external capacitance of the plane on the electrode, C I,air is the internal geometric capacitance of the air layer, C E,air is the external geometric capacitance of the air layer, C I,AC is the internal geometric capacitance of the asphalt mixture layer, C E,AC is the external geometric capacitance of the asphalt mixture layer, C I,substrate is the internal geometric capacitance of the substrate layer, C E,substrate is the external geometric capacitance of the substrate, N is the number of electrodes, ε air is the dielectric constant of air, ε AC is the dielectric constant of asphalt mixture, ε substrate is the dielectric constant of air, ε0 is the dielectric constant of vacuum, L is the length of electrode, k I,air 、k E,air 、k I,AC 、k E,AC 、k I,substrate 、k E,substrate are the modulus of the first kind of complete elliptic integral K(k) of the air layer, asphalt mixture layer and base layer when calculating the internal and external capacitance, respectively, and k' I,air , k' E,air , k' I , AC , k' E,AC , k' I,substrate , k' E,substrate They are the complementary moduli of the first kind complete elliptic integral K(k) of the air layer, asphalt mixture layer and base layer when calculating the internal and external capacitances, respectively.

[0021] Specifically, k E,air 、k I,air 、k I,AC 、k E,AC 、k E,substrate 、k I,substrate , k' E,air , k' I,air , k' I,AC , k' E,AC , k' E,substrate , k' I,substrateThe calculation formula is shown in Table 1 below, where η is the metallicity of the capacitive sensor, λ is the spatial wavelength of the capacitive sensor, h is the thickness of the dielectric layer, v2(x, y) and v3(x, y) are the second and third Jacobi functions, and sn(x, y) is the Jacobi elliptic function.

[0022] Table 1 calculates the internal and external capacitance (C I 、C E ) The calculation formula of k and k'

[0023]

[0024]

[0025] It should be noted that, in the present invention, the subscripts in the symbols are as follows: I represents the interior, E represents the exterior, air, AC, and substrate represent the air layer, asphalt mixture layer, and substrate layer, respectively. Based on this, for example, k I,air That is, the modulus of the first kind of complete elliptic integral K(k) of the air layer when calculating the internal capacitance, C I,air is the internal geometric capacitance of the air layer. Similarly, the definitions of other parameters can be obtained.

[0026] Furthermore, the process of establishing the relationship in S2 is:

[0027] S21. Asphalt mixture is considered as a three-phase composite material consisting of three raw materials: asphalt, aggregate and air;

[0028] S22. Based on the dielectric mixture model, the compaction density of the asphalt mixture is obtained according to the dielectric constant of the asphalt mixture and the dielectric constants and / or densities of various raw materials, and a relationship between the dielectric constant of the asphalt mixture and the compaction density is established.

[0029] Furthermore, the relationship between the dielectric constant and compaction density of asphalt mixture is expressed as:

[0030]

[0031] Where G mb is the density of asphalt mixture, ε AC is the dielectric constant of asphalt mixture, ε b is the dielectric constant of asphalt, ε s is the dielectric constant of the aggregate, P b is the asphalt content, G s is the aggregate density, G mm It is the maximum theoretical density of asphalt mixture.

[0032] Furthermore, in S4, the process of correcting the capacitance measurement value is as follows:

[0033] S41, based on the relationship in S1 and the actual detection in S3, obtain the theoretical and measured capacitance values ​​in the air domain, calculate the difference between them, and regard the difference as the parasitic capacitance;

[0034] S42. Correct the coplanar capacitance measurement value under the measured asphalt mixture domain by subtracting the parasitic capacitance value.

[0035] Furthermore, in S4, the expression used to correct the capacitance measurement value is:

[0036]

[0037] Where C s is the parasitic capacitance, C m,air is the capacitance value measured in air domain, C t,air is the theoretical capacitance value in air domain, C m,AC is the capacitance value measured in the asphalt mixture domain, C p is the measured capacitance value corrected in the asphalt mixture domain. Here, C t,air It is equal to C obtained by replacing the asphalt mixture layer in formula (1) with the air layer. total .

[0038] Furthermore, during the measurement of S5, first C p Substitute into S1, replacing C total First measure the corrected ε AC , then, based on the modified ε AC Calculate the corrected G mb .

[0039] In a second aspect, the present invention further provides an asphalt mixture compaction density detection device based on interdigital coplanar capacitance, which is used to implement the asphalt mixture compaction density detection method as described above, characterized in that the asphalt mixture compaction density detection device includes:

[0040] A coplanar capacitance acquisition unit, comprising an interdigital coplanar capacitance sensor for detecting capacitance values ​​and an LCR digital bridge for acquiring data;

[0041] The computer processing unit is configured to calculate the theoretical capacitance value in the air domain, eliminate the influence of parasitic capacitance, correct the measured capacitance value in the measured asphalt mixture domain, and calculate and obtain the accurate compaction density of the asphalt mixture based on the corrected capacitance measurement value.

[0042] In a third aspect, the present invention further provides an asphalt mixture compaction density detection system based on interdigital coplanar capacitance, which is used to implement the asphalt mixture compaction density detection method as described above, and the asphalt mixture compaction density detection system includes:

[0043] A capacitance detection module, comprising an interdigital coplanar capacitance sensor, configured to be placed in a tested area of ​​the asphalt mixture for detection;

[0044] a data acquisition module, comprising an LCR digital bridge, configured to acquire capacitance values ​​obtained by the interdigital coplanar capacitance sensor;

[0045] a data processing module configured to calculate a theoretical capacitance value in the air domain, calculate a parasitic capacitance based on the theoretical and measured capacitance values ​​in the air domain, and correct the measured capacitance value in the asphalt mixture domain based on the parasitic capacitance value;

[0046] The density calculation module is configured to calculate and obtain the accurate compaction density of the asphalt mixture based on the corrected measured capacitance value.

[0047] In a fourth aspect, the present invention further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the asphalt mixture compaction density detection method as described above.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) The asphalt mixture compaction density detection method based on interdigital coplanar capacitance proposed in the present invention can establish a theoretical relationship between the detection capacitance value and the asphalt mixture compaction density.

[0050] (2) The asphalt mixture compaction density detection method based on interdigital coplanar capacitance proposed in the present invention can eliminate the influence of parasitic capacitance, thereby improving the detection accuracy and obtaining the accurate asphalt mixture compaction density;

[0051] (3) The asphalt mixture compaction density detection system based on interdigital coplanar capacitance proposed in the present invention can be used to detect the compaction density of asphalt mixture and provide a basis for the quality control and evaluation of asphalt pavement construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of the structure of the asphalt mixture compaction density detection method based on interdigital coplanar capacitance of the present invention;

[0053] Figure 2 Schematic diagram of asphalt mixture compaction density detection based on interdigital coplanar capacitors of the present invention;

[0054] Figure 3 Schematic diagram of the interdigital coplanar capacitance sensor of the present invention;

[0055] Figure 4Schematic diagram of the structure of the asphalt mixture compaction density detection device based on interdigital coplanar capacitors of the present invention;

[0056] Figure 5 It is a structural schematic diagram of the asphalt mixture compaction density detection system based on interdigital coplanar capacitors of the present invention.

[0057] Description of the marks in the figure:

[0058] 1-Structure of asphalt mixture compaction density detection method based on interdigital coplanar capacitance, 2.1-Air layer, 2.2-Asphalt mixture to be tested, 3-Interdigital coplanar capacitance sensor, 3.1-Excitation electrode, 3.2-Detection electrode, 3.3-Substrate, 4-Asphalt mixture compaction density detection device, 4.1-Coplanar capacitance acquisition unit, 4.2-Computer processing unit, 5-Asphalt mixture compaction density detection system, 5.1-Capacitance detection module, 5.2-Data acquisition module, 5.3-Data processing module, 5.4-Density calculation module. DETAILED DESCRIPTION

[0059] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0060] Any features such as component models, material names, connection structures, control methods, algorithms, etc. that are not clearly stated in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0061] In order to obtain a more accurate distribution of asphalt mixture compaction density and provide a basis for asphalt pavement construction quality control and evaluation, the present invention provides an asphalt mixture compaction density detection method based on interdigital coplanar capacitance in some embodiments, which can be found in Figure 1 As shown, the following steps are included:

[0062] Step 1: Establish the relationship between the dielectric constant and capacitance value of asphalt mixture based on conformal mapping technology and partial capacitance technology. The specific construction process here is: S11, based on symmetry, divide the total capacitance value of the interdigital coplanar capacitance into the upper and lower planes of the electrode for solution, where the total capacitance of the upper or lower plane of the electrode is further decomposed into internal capacitance and external capacitance; S12, based on partial capacitance technology, decompose the internal capacitance and external capacitance again into the internal and external geometric capacitance of each measured dielectric layer; S13, based on the commonality mapping technology, obtain the internal and external geometric capacitance through the geometric parameters of the interdigital coplanar capacitance sensor and the dielectric constant of the measured dielectric layer; S14, finally establish the theoretical relationship between the dielectric constant of asphalt mixture and the detection capacitance value, that is, formula (1):

[0063]

[0064] Where C total is the total capacitance, C lower is the total capacitance of the plane under the electrode, C upper is the total capacitance of the electrode plane, C I，lower is the internal capacitance of the plane under the electrode, C E，lower is the external capacitance of the plane under the electrode, C I，upper is the internal capacitance of the plane on the electrode, C E,upper is the external capacitance of the plane on the electrode, C I,air is the internal geometric capacitance of the air layer, C E,air is the external geometric capacitance of the air layer, C I,AC is the internal geometric capacitance of the asphalt mixture layer, C E,AC is the external geometric capacitance of the asphalt mixture layer, C I,substrate is the internal geometric capacitance of the substrate layer, C E,substrate is the external geometric capacitance of the substrate, N is the number of electrodes, ε air is the dielectric constant of air, ε AC is the dielectric constant of asphalt mixture, ε substrate is the dielectric constant of air, ε0 is the dielectric constant of vacuum, L is the length of electrode, k E,air 、k I,air 、k I,AC 、k E,AC 、k E,substrate 、k I,substrate are the modulus of the first kind of complete elliptic integral K(k) of the air layer, asphalt mixture layer and base layer when calculating the internal and external capacitance, respectively, and k' E,air , k' I,air , k' I,AC , k' E,AC , k' E,substrate , k' I,substrate are the complementary modes of the first-kind complete elliptic integral K(k) for the air layer, asphalt mixture layer, and base layer when calculating the internal and external capacitances, respectively. The calculation formulas are shown in Table 1. Where η is the metallicity of the capacitance sensor, λ is the spatial wavelength of the capacitance sensor, h is the thickness of the dielectric layer, v2(x,y) and v3(x,y) are the second and third-kind Jacobi functions, and sn(x,y) is the Jacobi elliptic function.

[0065] Table 1 Calculation formulas for k and k' when calculating internal and external capacitance

[0066]

[0067] In some specific embodiments, the interdigital coplanar capacitance sensor 3 used in the present invention can be found in Figure 2and Figure 3 As shown, it includes an excitation electrode 3.1 and a detection electrode 3.2, which have the same geometric dimensions, exemplarily a width of 6 cm, a length of 27 cm, and an electrode spacing of 1 cm; it also includes a substrate 3.3, exemplarily made of glass fiber material, with a thickness of 5 cm and a dielectric constant of 4.5. In addition, 2.1 is an air layer with a thickness of 0.5 cm and a dielectric constant of 1. During the detection process, exemplarily, the thickness of the asphalt mixture 2.5 being tested is 5 cm. Based on the above data, combined with formula (1), the relationship between the capacitance value and the dielectric constant of the asphalt mixture can be obtained, and the theoretical capacitance value in the air domain can be calculated.

[0068] Step 2: Establish a theoretical relationship between the dielectric constant and compaction density of the asphalt mixture based on the volume and dielectric parameters of the asphalt mixture raw materials. The specific establishment process here is: S21, consider the asphalt mixture as a three-phase composite material composed of three raw materials: asphalt, aggregate, and air;

[0069] S22. According to the dielectric mixing model, the compaction density of the asphalt mixture is obtained according to the dielectric constant of the asphalt mixture and the dielectric constant and / or density of each raw material, and a relationship between the dielectric constant of the asphalt mixture and the compaction density is established, that is, formula (2):

[0070]

[0071] Where G mb is the density of asphalt mixture, ε AC is the dielectric constant of asphalt mixture, ε b is the dielectric constant of asphalt, ε s is the dielectric constant of the aggregate, P b is the asphalt content, G s is the aggregate density, G mm It is the maximum theoretical density of asphalt mixture.

[0072] In some specific embodiments, the present invention selects three types of asphalt mixtures, whose volumes and dielectric parameters are shown in Table 2. Based on the data in this table and combined with formula (2), the relationship between the dielectric constant and compaction density of the asphalt mixture can be obtained.

[0073] Table 2 Volume and dielectric parameters of asphalt mixture and its raw materials

[0074]

[0075] Step 3: Connect the excitation electrode and detection electrode of the interdigital coplanar capacitance sensor to the positive and negative poles of the LCR digital bridge, and collect capacitance measurement data in the air domain and the asphalt mixture domain respectively.

[0076] Step 4: Based on the theoretical air domain capacitance value calculated in S1 and the measured air domain capacitance value measured in S3, the parasitic capacitance is calculated according to formula (3), and the measured capacitance value under the asphalt mixture is corrected by subtracting the parasitic capacitance to eliminate the influence of the parasitic capacitance.

[0077] Specifically, the capacitance measurement value is corrected using formula (3) as follows:

[0078]

[0079] Where C s is the parasitic capacitance, C m,air is the capacitance value measured in air domain, C t,air is the theoretical capacitance value in air domain, C m,AC is the capacitance value measured in the asphalt mixture domain, C p is the corrected measured capacitance value in the asphalt mixture domain. t,air It is equal to C obtained by replacing the asphalt mixture layer in formula (1) with the air layer. total .

[0080] Step 5: Substitute the corrected detection capacitance value in S4 into the theoretical relationship established in S1 and S2. Specifically, first substitute the corrected detection capacitance value C p As C total Substituting into formula (1), we can calculate the corresponding ε AC , then, ε AC Substituting into formula (2), the accurate asphalt mixture compaction density G is calculated. mb .

[0081] In order to realize the above-mentioned asphalt mixture compaction density detection method based on interdigital coplanar capacitor, in some specific embodiments, the present invention further provides an asphalt mixture compaction density detection device 4 based on interdigital coplanar capacitor, see Figure 4 As shown, the device includes a coplanar capacitance acquisition unit 4.1 and a computer processing unit 4.2.

[0082] The coplanar capacitance acquisition unit 4.1 includes an interdigital coplanar capacitance sensor and an LCR digital bridge.

[0083] The coplanar capacitance acquisition unit is used to collect coplanar capacitance measurement values ​​in the air domain and under the asphalt mixture being tested; wherein the coplanar capacitance value acquisition is based on an interdigital coplanar capacitance sensor and an LCR digital bridge, wherein the interdigital coplanar capacitance sensor performs detection and the LCR digital bridge performs data acquisition.

[0084] The computer processing unit has built-in asphalt mixture compaction density calculation software. The computer processing unit uses the asphalt mixture compaction density calculation software to calculate the theoretical capacitance value in the air domain, obtain the parasitic capacitance value, and correct the measured capacitance value of the asphalt mixture under the test, and finally calculate the accurate asphalt mixture compaction density.

[0085] In order to realize the asphalt mixture compaction density detection method based on interdigital coplanar capacitance, in some specific embodiments, the present invention also provides an asphalt mixture compaction density detection system based on interdigital coplanar capacitance, see Figure 5 As shown, it includes a capacitance detection module 5.1, a data acquisition module 5.2, a data processing module 5.3 and a density calculation module 5.4.

[0086] The capacitance detection module 5.1 covers the interdigital coplanar capacitance sensor at a certain height above the surface of the asphalt mixture and performs capacitance detection;

[0087] The data acquisition module 5.2 uses an LCR digital bridge to acquire the measured coplanar capacitance value obtained based on the interdigital coplanar capacitance sensor;

[0088] The data processing module 5.3 calculates the theoretical capacitance value in the air domain, obtains the parasitic capacitance value, and corrects the measured capacitance value of the asphalt mixture to eliminate the influence of the parasitic capacitance;

[0089] The density calculation module 5.4 calculates the accurate compacted density of the asphalt mixture based on the corrected measured capacitance value.

[0090] Based on the above-mentioned asphalt mixture compaction density detection method, device and system based on interdigital coplanar capacitance, the three types of asphalt mixtures in step two are tested. Through the above steps, the compaction density of the asphalt mixture is effectively obtained, providing a basis for construction quality control.

[0091] In some specific embodiments, the present invention further proposes a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the asphalt mixture compaction density detection method as described above. The storage medium may be an electronic medium, a magnetic medium, an optical medium, an electromagnetic medium, an infrared medium, or a semiconductor system or a propagation medium. The storage medium may also include a semiconductor or solid-state memory, a magnetic tape, a removable computer disk, a random access memory (RAM), a read-only memory (ROM), a hard disk, and an optical disk. The optical disk may include a compact disk-read only memory (CD-ROM), a compact disk-read / write (CD-RW), and a DVD.

[0092] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such herein, will not be interpreted in an idealized or overly formal sense.

[0093] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for detecting compaction density of asphalt mixture based on interdigital coplanar capacitance, characterized in that: The following steps are involved: S1. Establishing the relationship between the dielectric constant and capacitance value of asphalt mixture based on conformal mapping technology and partial capacitance technology; S2. Establish the relationship between the dielectric constant and compaction density of asphalt mixture based on the dielectric mixture model; S3. Perform capacitance measurement on the asphalt mixture domain and the air domain to be measured, and obtain corresponding capacitance measurement values; S4. Correcting the capacitance measurement value in the asphalt mixture domain under test based on the parasitic capacitance; S5. Substituting the corrected capacitance measurement value in S4 into the relationship established in S1 and S2 to obtain the compacted density of the asphalt mixture being measured; The process of establishing the relationship in S1 is: S11. Based on symmetry, the total capacitance of the interdigital coplanar structure is divided into the upper and lower planes of the electrode for solution. The total capacitance of the upper or lower plane of the electrode is further decomposed into internal capacitance and external capacitance. S12. Based on the partial capacitance technique, the internal capacitance and the external capacitance are further decomposed into the internal and external geometric capacitances of each dielectric layer under test; S13, obtaining internal and external geometric capacitances using geometric parameters of the interdigital coplanar capacitance sensor and the dielectric constant of the measured dielectric layer according to the commonality mapping technology; S14, establishing a theoretical relationship between the dielectric constant of asphalt mixture and the detection capacitance value; The relationship between the dielectric constant and capacitance of asphalt mixture is expressed as: ， Where C total is the total capacitance, C lower is the total capacitance of the plane under the electrode, C upper is the total capacitance of the electrode plane, C I，lower is the internal capacitance of the plane under the electrode, C E，lower is the external capacitance of the plane under the electrode, C I，upper is the internal capacitance of the plane on the electrode, C E, upper is the external capacitance of the plane on the electrode, C I, air is the internal geometric capacitance of the air layer, C E, air is the external geometric capacitance of the air layer, C I, AC is the internal geometric capacitance of the asphalt mixture layer, C E, AC is the external geometric capacitance of the asphalt mixture layer, C I, substrate is the internal geometric capacitance of the substrate layer, C E, substrate is the external geometric capacitance of the substrate layer, N is the number of electrodes, ε air is the dielectric constant of air, ε AC is the dielectric constant of asphalt mixture, ε substrate is the dielectric constant of the substrate layer, ε 0 is the dielectric constant of vacuum, L is the electrode length, k I, air 、 k E, air 、 k I, AC 、 k E, AC 、 k I, substrate 、 k E, substrate The first kind of complete elliptic integrals for the air layer, asphalt mixture layer, and base layer when calculating internal and external capacitances respectively K ( k ) model, k’ I, air 、 k’ E, air 、 k’ I, AC 、 k’ E, AC 、 k’ I, substrate 、 k’ E, substrate The first kind of complete elliptic integrals for the air layer, asphalt mixture layer, and base layer when calculating internal and external capacitances respectively K ( k )'s complementary mode; The process of establishing the relationship in S2 is: S21. Asphalt mixture is considered as a three-phase composite material consisting of three raw materials: asphalt, aggregate and air; S22. Based on the dielectric mixture model, the compaction density of the asphalt mixture is obtained according to the dielectric constant of the asphalt mixture and the dielectric constants and / or densities of various raw materials, and a relationship between the dielectric constant of the asphalt mixture and the compaction density is established.

2. The method for detecting compaction density of asphalt mixture based on interdigital coplanar capacitance according to claim 1, wherein the asphalt The relationship between the dielectric constant of the mixture and the compacted density is expressed as: ， Where, G mb is the density of asphalt mixture, ε AC is the dielectric constant of asphalt mixture, ε b is the dielectric constant of asphalt, ε s is the dielectric constant of the aggregate, P b is the asphalt content, G s is the aggregate density, G mm It is the maximum theoretical density of asphalt mixture.

3. The method for detecting compaction density of asphalt mixture based on interdigital coplanar capacitance according to claim 1, characterized in that: In S4, the process of correcting the capacitance measurement value is as follows: S41, based on the relationship in S1 and the actual detection in S3, obtain the theoretical and measured capacitance values ​​in the air domain, calculate the difference between them, and regard the difference as the parasitic capacitance; S42. Correct the capacitance measurement value in the asphalt mixture domain by subtracting the parasitic capacitance value.

4. The method for detecting compacted density of asphalt mixture based on interdigital coplanar capacitance according to claim 1 or 3, characterized in that: In S4, the expression used to correct the capacitance measurement value is: ， Where, C s is the parasitic capacitance, C m, air is the capacitance value measured in air domain, C t, air is the theoretical capacitance value in air domain, C m, AC is the capacitance value measured in the asphalt mixture domain, C p is the measured capacitance value after correction in the asphalt mixture domain.

5. An asphalt mixture compaction density detection device based on interdigital coplanar capacitance, which is used to implement the asphalt mixture compaction density detection method according to claim 1, characterized in that: The asphalt mixture compaction density detection device comprises: A coplanar capacitance acquisition unit, comprising an interdigital coplanar capacitance sensor for detecting capacitance values ​​and an LCR digital bridge for acquiring data; A computer processing unit is configured to calculate theoretical capacitance values ​​in the air domain, eliminate the influence of parasitic capacitance, correct the capacitance values ​​measured in the asphalt mixture domain, and calculate and obtain the accurate compaction density of the asphalt mixture based on the corrected capacitance measurement values.

6. An asphalt mixture compaction density detection system based on interdigital coplanar capacitance, which is used to implement the asphalt mixture compaction density detection method according to claim 1, characterized in that: The asphalt mixture compaction density detection system includes: A capacitance detection module, comprising an interdigital coplanar capacitance sensor, configured to be placed in a tested area of ​​the asphalt mixture for detection; a data acquisition module, comprising an LCR digital bridge, configured to acquire capacitance values ​​obtained by the interdigital coplanar capacitance sensor; a data processing module configured to calculate a theoretical capacitance value in the air domain, calculate a parasitic capacitance based on the theoretical and measured capacitance values ​​in the air domain, and correct a capacitance value measured in the asphalt mixture domain based on the parasitic capacitance value; The density calculation module is configured to calculate and obtain the accurate compaction density of the asphalt mixture based on the corrected measured capacitance value.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the asphalt mixture compaction density detection method as claimed in claim 1 are implemented.

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