A sensor-based method for determining the timing of flushing permeable asphalt pavement.
By using a planar capacitance sensor to detect the degree of blockage in permeable asphalt pavement, the problem of low efficiency in traditional detection methods has been solved. This enables non-destructive and rapid blockage detection and flushing timing decisions, improving detection efficiency and adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTHEAST UNIV
- Filing Date
- 2024-01-24
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional road inspection methods are costly and inefficient, failing to meet the demands of modern highway inspection for speed, non-destructive testing, and intelligence. Furthermore, permeable asphalt pavements are susceptible to clogging by particulate matter, leading to a decline in functionality.
A planar capacitance sensor is used to detect the degree of blockage in permeable asphalt pavement. The capacitance value is converted into the degree of blockage through a fitting formula, which enables non-destructive and continuous detection and provides a basis for decision-making on when to flush the pavement.
It enables efficient and non-destructive testing of permeable asphalt pavements, significantly reduces testing time, provides quantitative testing references, and provides a basis for determining the timing of pavement washing, thus meeting the requirements of modern road rapid testing and maintenance.
Smart Images
Figure CN117926675B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a non-destructive testing technology for permeable asphalt pavement, and more particularly to a sensor-based method for determining the timing of washing permeable asphalt pavement. Background Technology
[0002] As a component of sponge cities, permeable asphalt pavement, with its high-porosity structure, can effectively reduce surface rainwater runoff and ensure driving safety. Its interconnected porous structure also provides sound absorption and noise reduction, and regulates surface temperature and humidity, significantly improving road service quality and mitigating the urban heat island effect. However, this high-porosity structure also makes it susceptible to clogging by particulate matter, reducing the effective porosity of permeable asphalt pavement, weakening its functionality, and even negatively impacting its service life.
[0003] my country's highway construction is shifting from high-speed to high-quality development, and the requirements for highway inspection and maintenance are becoming increasingly stringent, demanding faster, non-destructive, and intelligent processes. Traditional road inspection methods are costly, inefficient, and have long inspection cycles. They can cause structural damage to road inspection points, have limited applicability, and require stringent environmental conditions, thus failing to meet the inspection needs of modern road structures. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a sensor-based method for determining the flushing timing of permeable asphalt pavement. This method can convert the actual pavement capacitance value obtained by the planar capacitance sensor into the corresponding degree of blockage through a fitting formula, thereby achieving non-destructive continuous detection of the blockage state of asphalt pavement, improving pavement detection efficiency, and having significant implications for determining the flushing timing of permeable asphalt pavement.
[0005] The applicant believes that during the conceptualization process:
[0006] Planar capacitive sensors are capacitive sensors based on the edge effect detection principle. When the two electrodes are placed on the same plane, the electric field lines emitted by the positive electrode will point towards the negative electrode in an arc shape. When a non-metallic dielectric is introduced into the electric field, the electric field lines will be deflected, causing a change in the capacitance value. Planar capacitive sensors have advantages such as being non-invasive, radiation-free, portable, and low-cost.
[0007] The degree of clogging in permeable asphalt pavements affects road service quality. When clogging is high, the functionality of the permeable asphalt pavement decreases, surface runoff increases, and driving safety is negatively impacted. The decline in sound absorption, noise reduction, and moisture retention also negatively affects road service quality. Applying planar capacitive sensors to detect clogging in permeable asphalt pavements provides a non-destructive, continuous, and efficient method, offering significant advantages over traditional road detection methods and playing a crucial role in determining the appropriate timing for flushing permeable asphalt pavements.
[0008] The objective of this invention can be achieved through the following technical solutions:
[0009] This invention provides a sensor-based method for determining the timing of flushing permeable asphalt pavement, comprising the following steps:
[0010] (1) Prepare asphalt mixture specimens and use a planar capacitance sensor to obtain the initial capacitance value C of the specimens;
[0011] (2) The initial permeability coefficient K of the asphalt mixture specimen was tested using a permeability coefficient testing device;
[0012] (3) Multiple in-situ plugging tests were conducted on the asphalt mixture specimens. After each plugging test, the capacitance value C of the specimen was obtained using a planar capacitance sensor. n The permeability of the specimens was tested using a permeability testing device.
[0013] (4) The initial permeability coefficient K and the permeability coefficient after each group of plugging tests. Perform temperature correction to obtain the corrected permeability coefficient K. * ,
[0014] (5) Calculate the degree of asphalt mixture blockage I after each blockage test using the corrected permeability coefficient. n ;
[0015] (6) The degree of blockage I after each blockage test n and capacitance value C n By performing a fitting process, a fitting formula for the degree of blockage and the capacitance value is obtained;
[0016] (7) The actual permeable asphalt pavement is detected by a planar capacitance sensor to obtain the capacitance value of the asphalt mixture, and the theoretical blockage degree of the permeable asphalt pavement is obtained by the fitting formula.
[0017] (8) Make a decision on when to wash the permeable asphalt pavement based on the degree of blockage.
[0018] Furthermore, for newly constructed permeable asphalt roads, steps (1)-(7) can be adopted. First, asphalt mixture specimens are molded indoors. Then, the degree of blockage and capacitance value are obtained through testing, and the degree of blockage and capacitance value are fitted. Finally, after the road has been in use for a period of time, the actual permeable asphalt pavement is tested, and the theoretical degree of blockage obtained by fitting is calibrated with the actual degree of blockage, and applied to the actual pavement detection. For existing permeable asphalt roads, first, some statistically significant measurement points are selected. Then, the capacitance value is tested using a planar capacitance sensor, and the actual degree of blockage is obtained by conducting on-site permeability tests. Finally, the capacitance value of each point is fitted with the actual degree of blockage to obtain the fitting formula, which can then be applied to engineering practice.
[0019] Furthermore, in steps (1) and (3), the planar capacitance sensor includes two coplanar electrodes, an excitation power supply connected to the coplanar electrodes, a sensing electrode connected to the coplanar electrodes, and a data acquisition system connected to the sensing electrode.
[0020] Furthermore, the coplanar electrodes are made of copper sheets, each electrode plate is 40mm×12mm in size, the distance between the electrodes is 6mm, and the width of the shielding strip between the electrodes is 1mm;
[0021] When measuring the capacitance value of asphalt mixture specimens, place the specimen at the center of the planar capacitance sensor.
[0022] Furthermore, in steps (2) and (3), the asphalt mixture permeability coefficient testing apparatus includes:
[0023] Permeable cylinder: Located at the top of the asphalt mixture sample, used for injecting water from the upper surface of the asphalt mixture sample;
[0024] Metal sleeve: Located at the lower end of the permeable cylinder, used to fix the asphalt mixture sample and prevent seepage water from flowing out;
[0025] Overflow trough: The permeable cylinder, metal sleeve and asphalt mixture sample are all placed in the overflow trough, and the water seeping out from the lower surface of the asphalt mixture sample is collected in the overflow trough;
[0026] Ruler: Used to measure the dimensions of asphalt mixture samples, permeable cylinders, and overflow troughs;
[0027] The inner diameter of the permeable cylinder is matched with the diameter of the asphalt mixture sample.
[0028] Furthermore, in steps (2) and (3), the method for calculating the permeability coefficient is as follows: In the formula, Let T be the permeability coefficient (mm / s) of the specimen at a water temperature of T (°C) after the nth group of clogging tests, Q be the volume of water flowing out of the overflow pipe of the overflow tank within t (s) of the specimen (ml), L be the height of time (mm), and A be the upper surface area of the specimen (mm²). 2 H is the difference (mm) between the water level in the permeable cylinder and the water level in the overflow tank.
[0029] Further, in step (3), in the in-situ blocking test, particles with a diameter of 1.18-2.36 mm and 0.6-1.18 mm are selected and mixed to form blocking particles, wherein the proportion of 1.18-2.36 mm particles is 45.2% and the proportion of 0.6-1.18 mm particles is 54.8%.
[0030] In step (3), during the in-situ plugging test, 10g of plugging particles are evenly spread on the surface of the asphalt mixture each time. Then, the artificial rainfall simulation system is turned on, the rainfall intensity is 0.2mm / min, the rainfall time is 30s, and after the flushing is completed, it is waited for it to evaporate and dry. Then, the capacitance value and permeability coefficient are tested. A total of 10 in-situ tests are conducted.
[0031] Furthermore, in step (4), the temperature correction for the permeability coefficient involves unifying the permeability coefficient measured in the experiment to the permeability coefficient of the specimen at 15℃. The conversion method is as follows: In the formula, η represents the permeability coefficient (mm / s) of the specimen at standard temperature (15℃) after the nth group of clogging tests. T Let η be the dynamic viscosity coefficient of water at T (°C) (kPa·s). 15 The value is the dynamic viscosity coefficient of water at 15℃ (kPa·s).
[0032] Furthermore, in step (5), the method for calculating the degree of blockage in the asphalt mixture is as follows: That is, the degree of blockage = (1 - permeability coefficient after the nth blockage test / initial permeability coefficient) × 100%;
[0033] In step (6), the blockage degree and capacitance value data obtained from 10 experiments are input into the computer through the acquisition system, and the blockage degree and capacitance value are fitted using statistical software.
[0034] Furthermore, in step (7), before detecting the degree of blockage on the actual permeable asphalt pavement, the planar capacitance sensor needs to be calibrated. The steps include:
[0035] (1) Select a dry and flat area on the road surface to be tested, and draw a square with a size of 100mm×100mm with a point as the centroid. The centroid of the square is point 1.
[0036] (2) Place the planar capacitance sensor at the centroid and four vertices of the square to measure the capacitance value. Take the average of the five values as the capacitance value of point 1. The theoretical degree of blockage is obtained based on the fitting formula.
[0037] (3) Draw a square with a size of 400mm×400mm with point 1 as the centroid. Select the four vertices of the square and measure the capacitance value according to the above method to obtain the theoretical degree of blockage.
[0038] (4) Conduct field permeability tests on permeable asphalt pavement at 5 measuring points respectively, obtain the permeability coefficients at 5 points using a permeation device and perform temperature correction, and calculate the actual degree of blockage at 5 points.
[0039] (5) The theoretical degree of blockage is calibrated based on the actual degree of blockage and input into the planar capacitance sensor.
[0040] Furthermore, the main basis for the on-site pavement permeability coefficient measurement method is: JTG / T 0971-2008 "Specifications for On-site Testing of Highway Subgrade and Pavement";
[0041] The trial calculation method for the field permeability coefficient is as follows: In the formula, C w V1 is the water permeability coefficient of the road surface (mL / min), V2 is the water volume at the first timing (mL), usually 100mL, V3 is the water volume at the second timing (mL), usually 500mL, t1 is the time of the first timing (s), and t2 is the time of the second timing (s).
[0042] Compared with the prior art, the present invention has the following technical advantages:
[0043] (1) The present invention is simple to operate and can significantly reduce the testing time required in the acceptance process of permeable asphalt pavement;
[0044] (2) The present invention can detect blockages without damaging the permeable asphalt pavement structure and without affecting the pavement quality;
[0045] (3) The present invention can quantitatively detect the degree of blockage of permeable asphalt pavement, providing a reference indicator for the decision on when to wash the pavement;
[0046] (4) The present invention has low cost and rapid detection response, which meets the requirements of modern road rapid detection and maintenance. Attached Figure Description
[0047] Figure 1 This is a flowchart of a method for detecting the porosity of asphalt pavement based on a planar capacitance sensor under the condition of blockage in permeable asphalt pavement, as shown in the embodiment. Detailed Implementation
[0048] The sensor-based method for determining the timing of flushing permeable asphalt pavement in this invention includes the following steps:
[0049] (1) Prepare asphalt mixture specimens and use a planar capacitance sensor to obtain the initial capacitance value C of the specimens;
[0050] (2) The initial permeability coefficient K of the asphalt mixture specimen was tested using a permeability coefficient testing device;
[0051] (3) Multiple in-situ plugging tests were conducted on the asphalt mixture specimens. After each plugging test, the capacitance value C of the specimen was obtained using a planar capacitance sensor. n The permeability of the specimens was tested using a permeability testing device.
[0052] (4) Temperature correction was applied to the initial and post-blocking permeability coefficients to obtain the corrected permeability coefficient K. * ,
[0053] (5) Calculate the degree of asphalt mixture blockage I after each blockage test using the corrected permeability coefficient. n ;
[0054] (6) The degree of blockage I after each blockage test n and capacitance value C n By performing a fitting process, a fitting formula for the degree of blockage and the capacitance value is obtained;
[0055] (7) The actual permeable asphalt pavement was tested using a planar capacitance sensor to obtain the capacitance value of the asphalt mixture, and the theoretical blockage degree of the permeable asphalt pavement was obtained by fitting the formula.
[0056] (8) Taking the capacitance value test point as the center, conduct on-site permeability test on the permeable asphalt pavement to obtain the actual degree of blockage, and use the actual degree of blockage to calibrate the theoretical degree of blockage;
[0057] (9) Decisions are made on the timing of flushing permeable asphalt pavement based on the degree of blockage.
[0058] In practice, it is optional to prepare specimens indoors using the hot-mix raw material method, in accordance with the design method for asphalt mixtures for new roads.
[0059] In specific implementation, the asphalt mixture specimens can be prepared using the standard compaction method, with 50 compaction cycles to form the specimens, resulting in specimen dimensions of φ101.6mm × 63.5mm. Alternatively, the asphalt mixture can be prepared using the rotary compaction method, with rotary compaction performed at 35, 40, 45, 50, and 55 cycles respectively, resulting in cylindrical specimens with a diameter of 100mm.
[0060] In specific implementation, it is optional that in steps (1) and (3), the planar capacitance sensor is a two-electrode planar capacitance sensor, including a planar electrode device and a data acquisition system. The data acquisition system is used to control the planar electrodes to perform measurements, and the capacitance value is detected by the sensing electrode by applying a voltage to the excitation electrode. The planar electrode device includes:
[0061] (1) The two coplanar electrodes are made of copper sheets, each electrode plate is 40mm×12mm in size, the distance between the electrodes is 6mm, and the width of the shielding strip between the electrodes is 1mm.
[0062] (2) The planar capacitive sensor is fixed on a substrate made of polyimide;
[0063] (3) When measuring the capacitance value of asphalt mixture specimens, place the specimen at the center of the planar capacitance sensor.
[0064] The penetration depth T of a planar capacitive sensor depends on the sensor's geometry and is proportional to the distance between the centerlines of the two coplanar electrodes, i.e., it is related to the electrode width s and the distance g between the two electrodes, conforming to the formula:
[0065] T = 1.35g + 0.65s
[0066] In engineering applications, planar capacitive sensors with different configurations can be selected based on actual conditions. Planar capacitive sensors with wide electrodes and wide spacing can penetrate materials more deeply and reach further away from their surface. For the blockage situation of permeable asphalt pavement, the maximum blockage depth is generally less than 10mm, and electrode parameters can be selected according to the blockage situation. However, it should be noted that as the electrode spacing g increases, the effective capacitance value will gradually decrease. C changes approximately exponentially with the electrode spacing g, satisfying the formula:
[0067] C = α(g) β
[0068] Where α is a parameter related to the electrode width.
[0069] In specific implementation, the preferred method for obtaining the capacitance value using a planar capacitance sensor in step (1) is to place the asphalt mixture specimen at the center of the planar capacitance sensor probe, read the sensor reading once every 30 seconds, read a total of 4 readings, and take the average value as the capacitance value of the specimen.
[0070] In specific implementation, the preferred method for obtaining capacitance value using a planar capacitance sensor in step (3) is as follows: after each group of blockage test and permeability coefficient test is completed, and the asphalt mixture specimen is dried, the asphalt mixture specimen is placed in the center of the planar capacitance sensor probe, and the sensor reading is read once every 30 seconds. A total of 4 readings are read, and the average value is taken as the capacitance value of the specimen.
[0071] In specific implementation, the preferred method for testing the permeability coefficient of asphalt mixture in steps (2) and (3) includes: a permeable cylinder, a permeable cylinder overflow pipe, an overflow trough, a trough overflow pipe, a metal sleeve, sealing material, a ruler, etc. The permeability coefficient is calculated as follows: In the formula, Let T be the permeability coefficient (mm / s) of the specimen at a water temperature of T (°C) after the nth group of clogging tests, Q be the volume of water flowing out of the overflow pipe of the overflow tank within t (s) of the specimen (ml), L be the height of time (mm), and A be the upper surface area of the specimen (mm²). 2 H is the difference (mm) between the water level in the permeable cylinder and the water level in the overflow tank.
[0072] In specific implementation, the preferred method is to conduct an in-situ plugging test on the asphalt mixture in step (3). Each time, 10g of plugging particles are evenly spread on the surface of the asphalt mixture, and then the artificial rainfall simulation system is turned on. The rainfall intensity is 0.2mm / min, and the rainfall time is 30s. After the flushing is completed, wait for it to evaporate and dry, and then test the capacitance value and permeability coefficient. A total of 10 in-situ tests are conducted.
[0073] In specific implementation, the preferred step (4) involves temperature correction of the permeability coefficient to unify the permeability coefficient measured in the experiment to the permeability coefficient of the specimen at 15℃. The conversion method is as follows: In the formula, η represents the permeability coefficient (mm / s) of the specimen at standard temperature (15℃) after the nth group of clogging tests. T Let η be the dynamic viscosity coefficient of water at T (°C) (kPa·s). 15 The value is the dynamic viscosity coefficient of water at 15℃ (kPa·s).
[0074] In specific implementation, the preferred method for calculating the degree of blockage of the asphalt mixture in step (5) is as follows: That is, the degree of blockage = (1 - permeability coefficient after the nth blockage test / initial permeability coefficient) × 100%.
[0075] In specific implementation, it is preferred that in step (6), the degree of blockage and capacitance value obtained from 10 tests are input into the computer, and statistical software is used to fit the degree of blockage and capacitance value.
[0076] In specific implementation, preferably, before performing porosity detection on the actual road surface in steps (7) and (8), the planar capacitance sensor needs to be calibrated. The steps include:
[0077] (1) Select a dry and flat area on the road surface to be tested, and draw a square with a size of 100mm×100mm with a point as the centroid. The centroid of the square is point 1.
[0078] (2) Place the planar capacitance sensor at the centroid and four vertices of the square to measure the capacitance value. Take the average of the five values as the capacitance value of point 1. The theoretical degree of blockage is obtained based on the fitting formula.
[0079] (3) Draw a square with a size of 400mm×400mm with point 1 as the centroid. Select the four vertices of the square and measure the capacitance value according to the above method to obtain the theoretical degree of blockage.
[0080] (4) Conduct field permeability tests on permeable asphalt pavement at 5 measuring points respectively, obtain the permeability coefficients at 5 points using a permeation device and perform temperature correction, and calculate the actual degree of blockage at 5 points.
[0081] (5) The theoretical degree of blockage is calibrated based on the actual degree of blockage and input into the planar capacitance sensor.
[0082] In specific implementation, the preferred method for measuring the pavement permeability coefficient in step (8) is based on JTG / T0971-2008 "Specifications for Field Testing of Highway Subgrade and Pavement". The instruments and materials required for the field permeability coefficient test include: a pavement permeability meter, a water tank and large funnel, a stopwatch, sealing materials (waterproof putty, putty, or modeling clay) and other materials (water, chalk, plastic rings, scrapers, brooms, etc.). The calculation method is as follows: In the formula, C w V1 is the water permeability coefficient of the road surface (mL / min), V2 is the water volume at the first timing (mL), usually 100mL, V3 is the water volume at the second timing (mL), usually 500mL, t1 is the time of the first timing (s), and t2 is the time of the second timing (s).
[0083] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0084] Unless otherwise specified in this technical solution, the component model, material name, connection structure, control method, algorithm, and other features are considered to be common technical features disclosed in the prior art.
[0085] Example 1
[0086] An example of using a planar capacitance sensor to detect the degree of blockage on a newly constructed permeable asphalt road.
[0087] Figure 1This is a flowchart of a method for detecting the porosity of permeable asphalt pavement using a planar capacitive sensor under blocked conditions, according to the present invention. The method includes the following steps:
[0088] (1) Based on the design method of actual pavement asphalt mixture, specimens were molded indoors. The specimens were prepared by hot-mix raw material method and molded by standard compaction method. The size of the asphalt mixture specimens was φ101.6mm×63.5mm. After the specimens were compacted, they were placed at room temperature for 24 hours before demolding.
[0089] The porosity of the asphalt mixture specimens after demolding was calculated to be 20.4%, which meets the porosity requirements for permeable asphalt pavement.
[0090] (2) Place the asphalt mixture specimen at the center of the planar capacitance sensor probe, ensuring the instrument remains stable and the sensor is in close contact with the specimen surface. Then, start the sensor; the capacitance measurement will be completed within 1-2 seconds. Measure the instrument every 30 seconds, for a total of 4 measurements, and use the average value as the specimen's capacitance value.
[0091] (3) Obtain the initial permeability coefficient of the asphalt mixture specimen. Subsequently, 10 sets of clogging tests were conducted on the asphalt mixture specimen. After each set of tests was completed and the specimen was evaporated and dried, the capacitance value was measured and the permeability coefficient was tested using the above method.
[0092] The permeability coefficient testing apparatus includes: a permeable cylinder, a permeable cylinder overflow pipe, an overflow tank, a tank overflow pipe, a metal sleeve, sealing material, a ruler, etc. The calculation method is as follows: In the formula, Let T be the permeability coefficient (mm / s) of the specimen at a water temperature of T (°C) after the nth group of clogging tests, Q be the volume of water flowing out of the overflow pipe of the overflow tank within t (s) of the specimen (ml), L be the height of time (mm), and A be the upper surface area of the specimen (mm²). 2 H is the difference (mm) between the water level in the permeable cylinder and the water level in the overflow tank.
[0093] (4) Temperature correction was applied to the permeability coefficients after the initial and clogging tests to unify them to the permeability coefficients of the specimens at 15℃. The method was as follows: In the formula, η represents the permeability coefficient (mm / s) of the specimen at standard temperature (15℃) after the nth group of clogging tests. T Let η be the dynamic viscosity coefficient of water at T (°C) (kPa·s). 15 The value is the dynamic viscosity coefficient of water at 15℃ (kPa·s).
[0094] The degree of blockage in the asphalt mixture specimens after each blockage test was calculated using the following method: That is, the degree of blockage = (1 - permeability coefficient after the nth blockage test / initial permeability coefficient) × 100%.
[0095] The results of the specimen blockage degree and capacitance value are shown in Table 2 below:
[0096] Table 2
[0097] Blockage test degree of congestion capacitance value No clogging test was conducted. 0.00％ 18.13pF One blockage test 34.68％ 19.54pF Two blocking tests 60.18％ 20.88pF 3 blockage tests 64.26％ 21.12pF 4 blockage tests 66.78％ 21.28pF 5 blockage tests 72.46％ 21.52pF 6 blockage tests 74.48％ 21.58pF 7 blockage tests 78.58％ 21.78pF 8 blockage tests 80.12％ 21.84pF 9 blockage tests 86.28％ 22.22pF 10 blockage tests 88.48％ 22.34pF
[0098] (5) Using statistical software and the least squares method, the degree of congestion I is determined. n A binomial fit was performed with the capacitance value C, and the fitting equation was obtained as follows:
[0099] I n = -0.0064C 2 +0.4687C -6.3736
[0100] After the newly constructed permeable asphalt road has been in use for a period of time, the planar capacitance sensor should be calibrated before testing the actual permeable asphalt road surface. The steps are as follows:
[0101] (1) Select a dry and flat area on the road surface to be tested, and draw a square with a size of 100mm×100mm with a point as the centroid. The centroid of the square is point 1.
[0102] (2) Place the planar capacitance sensor at the centroid and four vertices of the square to measure the capacitance value. Take the average of the five values as the capacitance value of point 1. The theoretical degree of blockage is obtained based on the fitting formula.
[0103] (3) Draw a square with a size of 400mm×400mm with point 1 as the centroid. Select the four vertices of the square and measure the capacitance value according to the above method to obtain the theoretical degree of blockage.
[0104] (4) Conduct field permeability tests on permeable asphalt pavement at 5 measuring points respectively, obtain the permeability coefficients at 5 points using a permeation device and perform temperature correction, and calculate the actual degree of blockage at 5 points.
[0105] The main basis for the on-site pavement permeability coefficient measurement method is JTG / T 0971-2008 "Specifications for On-site Testing of Highway Subgrade and Pavement". The instruments and materials required for the on-site permeability coefficient test include: a pavement permeability meter, a water cylinder and large funnel, a stopwatch, sealing materials (waterproof putty, putty or modeling clay) and other materials (water, chalk, plastic rings, scraper, broom, etc.). The calculation method is as follows: In the formula, C wV1 is the water permeability coefficient of the road surface (mL / min), V2 is the water volume at the first timing (mL), usually 100mL, V3 is the water volume at the second timing (mL), usually 500mL, t1 is the time of the first timing (s), and t2 is the time of the second timing (s).
[0106] The calibration results are shown in Table 3 below:
[0107] Table 3
[0108]
[0109] The degree of congestion, I, is calculated using statistical software and the least squares method. n And the actual degree of congestion I r After fitting and calibration, the following relationship was obtained:
[0110] I r =0.992I n +0.0048
[0111] The above method can be used to quickly, non-destructively, and continuously detect the degree of blockage of permeable asphalt pavement using planar capacitance, which is of great significance for the decision-making on the timing of modern road washing. That is, when the degree of blockage of permeable asphalt pavement reaches the threshold, road washing should be carried out.
[0112] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any 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 invention should be within the protection scope of the present invention.
Claims
1. A method for determining the timing of flushing permeable asphalt pavement based on sensor detection, characterized in that, Includes the following steps: (1) Prepare asphalt mixture specimens and use a planar capacitance sensor to obtain the initial capacitance value of the specimens. ; (2) Using a permeability coefficient testing device, the initial permeability coefficient of the asphalt mixture specimen was tested. ; (3) Multiple in-situ plugging tests were conducted on the asphalt mixture specimens. After each plugging test, the capacitance value of the specimens was obtained using a planar capacitance sensor. The permeability coefficient of the specimens at water temperature T℃ was tested using a permeability coefficient testing device. ; (4) Regarding the initial permeability coefficient and the permeability coefficient after each group of plugging tests Perform temperature correction and obtain the permeability coefficient corrected to the standard temperature. Permeability coefficient after the nth group of plugging tests ; (5) Calculate the degree of blockage of the asphalt mixture after each blockage test using the corrected permeability coefficient. ; (6) Determine the degree of blockage after each blockage test. and capacitance value By performing a fitting process, a fitting formula for the degree of blockage and the capacitance value is obtained; (7) The actual permeable asphalt pavement is detected by a planar capacitance sensor to obtain the capacitance value of the asphalt mixture, and the theoretical blockage degree of the permeable asphalt pavement is obtained by the fitting formula. (8) Make a decision on when to wash the permeable asphalt pavement based on the degree of blockage.
2. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 1, characterized in that, In steps (1) and (3), the planar capacitance sensor includes two coplanar electrodes, an excitation power supply connected to the coplanar electrodes, a sensing electrode connected to the coplanar electrodes, and a data acquisition system connected to the sensing electrode.
3. The method for determining the timing of flushing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, The coplanar electrodes are made of copper sheets, each electrode plate having a size of... The spacing between the electrodes is The width of the inter-electrode shielding strip is ; When measuring the capacitance value of asphalt mixture specimens, place the specimen at the center of the planar capacitance sensor.
4. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, In steps (2) and (3), the asphalt mixture permeability coefficient test apparatus includes: Permeable cylinder: Located at the top of the asphalt mixture sample, used for injecting water from the upper surface of the asphalt mixture sample; Metal sleeve: Located at the lower end of the permeable cylinder, used to fix the asphalt mixture sample and prevent seepage water from flowing out; Overflow trough: The permeable cylinder, metal sleeve and asphalt mixture sample are all placed in the overflow trough, and the water seeping out from the lower surface of the asphalt mixture sample is collected in the overflow trough; Ruler: Used to measure the dimensions of asphalt mixture samples, permeable cylinders, and overflow troughs; The inner diameter of the permeable cylinder is matched with the diameter of the asphalt mixture sample.
5. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, In steps (2) and (3), the method for calculating the permeability coefficient is as follows: In the formula, After the nth group of blockage tests, the water temperature was The permeability coefficient of the specimen, in units of , For test specimens The amount of water flowing out of the overflow pipe of the overflow tank within seconds , The height of time, in units of , The upper surface area of the specimen is given in units of 1000 m². , The difference between the water level in the permeable cylinder and the water level in the overflow tank, expressed in units of... .
6. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, In step (3), during the in-situ blockage test, a particle size of [missing value] is selected. and The particles are mixed and configured into clogging particles, wherein The particle content was 45.2%. The proportion of particles was 54.8%; In step (3), in the in-situ plugging test, 10g of plugging particles are evenly spread on the surface of the asphalt mixture each time, and then the artificial rainfall simulation system is turned on. The rainfall intensity is 0.2mm / min and the rainfall time is 30s. After the flushing is completed, wait for it to evaporate and dry. Then, the capacitance value and permeability coefficient are tested. A total of 10 in-situ tests are carried out.
7. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, In step (4), the temperature correction for the permeability coefficient is to unify the permeability coefficient measured in the experiment to a constant value. The permeability coefficient of the specimen is converted using the following method: In the formula, After the nth group of blockage tests, the specimen was subjected to standard temperature. The permeability coefficient of the specimen, in units of , for The dynamic viscosity coefficient of water, in units of , for The dynamic viscosity coefficient of water, in units of .
8. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 1, characterized in that, In step (5), the method for calculating the degree of blockage in the asphalt mixture is as follows: That is, the degree of blockage = (1 - permeability coefficient after the nth blockage test / initial permeability coefficient) × 100%; In step (6), the blockage degree and capacitance value data obtained from 10 experiments are input into the computer through the acquisition system, and the blockage degree and capacitance value are fitted using statistical software.
9. The method for determining the timing of washing permeable asphalt pavement based on sensor detection according to claim 2, characterized in that, In step (7), before detecting the degree of blockage on the actual permeable asphalt pavement, the planar capacitance sensor needs to be calibrated. The steps include: (1) Select a dry and flat area on the road surface to be inspected, and draw a circle with a size of 1.5 as the centroid. A square, with point 1 as its centroid; (2) The planar capacitance sensor was placed at the centroid and four vertices of the square to measure the capacitance value. The average of the five values was taken as the capacitance value of point 1. The theoretical degree of blockage was obtained based on the fitting formula. (3) Draw a circle with point 1 as the centroid and a dimension of [missing information]. For a square, select 4 vertices of the square and measure the capacitance value using the method described above to obtain the theoretical degree of blockage; (4) Conduct field permeability tests on permeable asphalt pavement at 5 measuring points respectively, obtain the permeability coefficients at 5 points using a permeation device and perform temperature correction, and calculate the actual degree of blockage at 5 points. (5) The theoretical degree of blockage is calibrated based on the actual degree of blockage and input into the planar capacitance sensor.