A system for identifying the movement state of particles of aeolian sand asphalt pavement and its use method

Abstract

The invention belongs to the field of civil engineering, and discloses a system for identifying the movement state of aeolian sand asphalt pavement particles and a method for using the system. The system comprises a base plate with support legs installed at the four corners of the bottom; a lifting device for driving a lifting plate to move up and down is installed on the base plate, a frequency modulation controller and a motor are fixed on the lifting plate, a rotating shaft is connected to the motor, the lower end of the rotating shaft passes through the base plate and a flywheel and a turntable are arranged; a plurality of rubber blocks are installed at the bottom of the turntable; a linear velocity sensor, a rotational velocity sensor and a torque sensor connected to a computer are respectively arranged on the rotating shaft; the system can simulate the dynamic migration process of aeolian sand particles on a real asphalt pavement at different initial velocities and aeolian sand densities, and obtain the variation trend of the friction coefficient value of the pavement at different aeolian sand densities through computer processing using the information obtained by the linear velocity sensor and the torque sensor, thereby providing an effective means for studying the anti-skid performance of the asphalt pavement; the method is simple, repeatable and stable.

Description

Technical Field

[0001] The present invention relates to the field of civil engineering technology, and in particular to a system for identifying the movement state of aeolian sand asphalt pavement particles and a method for using the system, which are used to observe and identify the movement state of aeolian sand particles on asphalt pavements in desert areas, understand the movement and migration state of aeolian sand particles, determine their friction coefficient, and evaluate the anti-skid performance of asphalt pavements. Background Art

[0002] With the rapid development of modern transportation, people's demand for roads is no longer limited to satisfying basic functions such as convenience, efficiency, and speed, but focuses on how to improve driving safety and driving comfort. The lack of anti-skid performance of asphalt pavement is an important factor leading to frequent traffic accidents. Within the design service life, under the long-term combined effects of factors such as driving load and natural environment, a lot of pollutants will accumulate and cover the road surface. Once the density of pollutants exceeds a certain range, it is bound to significantly weaken the anti-skid driving ability of the road surface. For desert areas, due to the year-round drought and little rain, blowing sand, sandstorms, and dust weather are common, resulting in the inevitable phenomenon of "sand accumulation" on the road surface of desert roads. The sand attached to the road surface will significantly affect the contact characteristics between the tire and the road surface, and the road's anti-skid ability will be sharply reduced, greatly affecting driving safety.

[0003] The anti-skid performance of pavement mainly includes two parts: the surface structure depth and the friction coefficient. The surface structure depth is usually tested by sand spreading method, digital imaging technology, 3D laser scanner, etc. The friction coefficient is usually collected by pendulum friction coefficient tester, dynamic rotation friction coefficient tester, SCRIM lateral force coefficient test vehicle, etc. to collect anti-skid performance indicators such as pendulum value, dynamic friction coefficient, lateral force coefficient, etc. The environmental factors that affect the anti-skid performance of asphalt pavement mainly include water accumulation, ice and snow, oil pollution, tire crumbs, mud, etc. In existing studies, numerical simulation is often used to explore the contact characteristics of tire-pavement in the presence of pollutants.

[0004] At present, there have been many research results on the anti-skid decay characteristics of asphalt pavement, but they are mainly conducted on pavement without pollutants or water accumulation and ice formation on the road surface. There is a lack of detailed research on the anti-skid performance of desert roads and the mechanical behavior of aeolian sand. Water accumulation and ice formation on the road surface can usually be simulated by finite elements, but the movement behavior of aeolian sand on the tire / road contact interface cannot be simply applied to the existing research results due to the heterogeneity and anisotropy of the particles. Summary of the invention

[0005] To solve the above problems, the present invention provides a system for identifying the movement state of aeolian sand asphalt pavement particles and a method for using the system. The system can simulate the dynamic migration process of aeolian sand particles on a real asphalt pavement, and by changing the initial rotation speed of a turntable and the density of aeolian sand, a high-speed camera is used to observe the migration and movement state of the marked aeolian sand particles at different initial turntable speeds and aeolian sand densities. The information obtained by a linear velocity sensor and a torque sensor is processed by a computer to obtain the change trend of the road friction coefficient value at different aeolian sand densities, thereby providing an effective means for studying the anti-skid performance of asphalt pavements in desert areas. The method is simple and has the advantages of repeatability, stability and significant data differences.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions.

[0007] (1) A system for identifying the movement state of particles on aeolian sand asphalt pavement, comprising a base plate, a computer and a camera; wherein support legs are symmetrically installed at the four corners of the bottom of the base plate; a lifting plate is arranged above the base plate, and a lifting device is installed on the base plate, and the lifting device is used to drive the lifting plate to move up and down;

[0008] The lifting plate is respectively fixed with a frequency modulation controller and a motor, wherein a signal output end of the frequency modulation controller is electrically connected to a signal input end of the motor; the frequency modulation controller is connected to the computer via a wireless network;

[0009] A rotating shaft is vertically connected to the output shaft of the motor, the lower end of the rotating shaft passes through the bottom plate and a flywheel and a turntable are arranged in sequence from top to bottom; a plurality of rubber blocks are evenly installed circumferentially at the bottom of the turntable through a spring sheet;

[0010] A linear speed sensor, a rotation speed sensor and a torque sensor are respectively arranged on the rotating shaft, and the linear speed sensor, the rotation speed sensor and the torque sensor are respectively connected to the computer via a wireless network;

[0011] The cameras are respectively arranged around the bottom plate, and are used to observe and record the migration and movement state of aeolian sand under different initial rotation speeds of the turntable and aeolian sand densities.

[0012] Preferably, the size of the rubber block is 3cm×3cm×2cm.

[0013] Preferably, the lifting device is an electric push rod; the electric push rod is symmetrically mounted on the base plate, and the upper end of the telescopic rod of the electric push rod is horizontally fixedly connected to the lifting plate.

[0014] Preferably, the linear velocity sensor is used to obtain the vertical falling speed information of the rotating shaft, and transmit the obtained vertical falling speed information of the rotating shaft to the computer; the torque sensor is used to obtain torque value information, and transmit the obtained torque value information to the computer; the computer calculates the friction coefficient between the rubber block and the aeolian sand particles based on the information obtained by the linear velocity sensor and the torque sensor.

[0015] Preferably, the rotation speed sensor is used to obtain real-time rotation speed information of the turntable.

[0016] Preferably, a spring is connected between the flywheel and the turntable.

[0017] Preferably, a spring damper is provided on the base plate.

[0018] Preferably, it further comprises a rutting plate, wherein the rutting plate is located below the supporting legs of the base plate; aeolian sand of different densities is placed on the rutting plate, and the aeolian sand is marked with colors.

[0019] Preferably, a memory is further included, and the signal output ends of the linear speed sensor, the rotational speed sensor and the torque sensor are electrically connected to the signal input ends of the memory respectively.

[0020] (II) A method for using a system for identifying the movement state of particles of aeolian sand asphalt pavement, comprising the following steps:

[0021] Step 1: Place the support legs in the aeolian sand asphalt pavement particle motion state recognition system on the asphalt pavement to be tested, and place cameras around the bottom plate respectively;

[0022] Step 2, laying aeolian sand of different densities on the asphalt pavement to be tested;

[0023] Step 3, control the motor to drive the turntable to rotate at different set initial speeds through the frequency modulation controller to ensure that the bottom surface of the rubber block on the turntable does not contact the aeolian sand, and at the same time, turn on the camera to continuously shoot the movement state of the aeolian sand particles;

[0024] Step 4: After the turntable reaches the set initial speed, the motor stops working, and the electric push rod controls the lifting plate to move downward, driving the rotating shaft, flywheel, turntable and rubber block to fall, so that the rubber block contacts the aeolian sand particles, and the electric push rod stops working. At this time, the torque sensor collects the torque value information of the rotating shaft, the linear speed sensor collects the vertical falling speed value information of the rotating shaft, and the rotation speed sensor collects the real-time rotation speed information of the turntable;

[0025] Step 5: Due to the friction between the rubber block and the asphalt road surface to be tested, the turntable gradually slows down and finally stops, the torque sensor, the linear speed sensor and the rotation speed sensor stop collecting data, and the camera stops shooting;

[0026] Step 6: The computer calculates the friction coefficient μ between the rubber block and the aeolian sand particles based on the information collected by the torque sensor and the linear velocity sensor.

[0027] Preferably, in step 1, the asphalt pavement to be tested is a rutting plate or a solid asphalt pavement.

[0028] Preferably, in step 6, the friction coefficient μ between the rubber block and the aeolian sand particles is calculated as follows:

[0029]

[0030] Wherein, M is the torque value of the rotating shaft collected by the torque sensor; m is the mass of the lifting plate, flywheel, turntable, rubber block and spring sheet; L is the circumference of the circle with the distance from the rotating shaft to the rubber block as the radius; It is the vertical falling speed value of the rotating shaft collected by the linear speed sensor; is the inverse of acceleration.

[0031] Preferably, the method further includes step 7, converting the motion state of the aeolian sand particles continuously photographed by the camera into a single-frame image, and determining the particle flow Q ejected from the contact point between the rubber block and the asphalt pavement to be tested according to the single-frame image. L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R ;

[0032] According to the particle flow Q ejected from the contact point between the rubber block and the asphalt road to be tested L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R Calculate the injection ratio IR L and recirculation ratio IR R , as follows:

[0033]

[0034]

[0035] The particle flow velocity is estimated by the following formula

[0036]

[0037] Among them, n p is the number of pixels separating the particle positions between two given frames, and △t is the time interval between the two frames.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] (1) The road aeolian sand movement state identification system of the present invention has a simple structure, convenient operation, intuitive and clear operation, and is repeatable, stable and accurate. The working state of the frequency modulation controller can be changed by computer software, and the frequency modulation controller can accurately control the motor speed. The motor drives the rotating shaft to rotate at a constant speed and can simulate different initial speeds on the turntable. The density of aeolian sand can be adjusted and controlled manually, and two variables of different turntable initial speeds and different aeolian sand densities can be simulated in the laboratory. The speed information and torque value information of the vertical falling of the rotating shaft are collected by a linear velocity sensor and a torque sensor. The change trend of the road friction coefficient value under different turntable initial speeds and aeolian sand densities is obtained through computer processing, which provides a new research direction for observing the movement state of particles under sand-accumulated roads and is of great significance for exploring the actual tire-sand-road contact state and sand movement mode under sand-accumulated roads.

[0040] (2) By installing support legs at the four corners of the bottom of the base plate, the camera has a wide viewing angle to ensure the accuracy of the recording. The size of the rubber block is 3cm×3cm×2cm, which can prevent the rubber block from generating torsional shear deformation during the operation of the device. The design of the size of the rubber block and the dyeing of the aeolian sand density can facilitate the high-speed camera to record the migration and movement state of aeolian sand particles under different turntable initial speeds and aeolian sand densities. The subsequent computer processing can improve the observation accuracy. The camera observation operation is convenient, intuitive and clear, which overcomes the problem that the existing test instruments do not consider the actual tire-sand-road contact state and sand movement mode on the aeolian sand road surface.

[0041] (3) The road aeolian sand movement state identification system of the present invention is simple to use and has the advantages of repeatability, stability and significant data difference. The particle flow Q ejected from the rubber block and the contact point of the asphalt road surface to be tested in the movement state diagram of the aeolian sand particles recorded by the high-speed camera is obtained by using Premiere Pro 2018 software. L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R Two parameters, and the injection ratio IR is calculated based on these two parameters L and recirculation ratio IR R , and then the movement and migration process of aeolian sand particles can be identified from a microscopic perspective, and how the initial rotation speed of the turntable affects the injection ratio IR can be analyzed L and recirculation ratio IR R ; And the anti-skid performance of asphalt pavement in desert areas can be analyzed by the obtained friction coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Figure 1 It is a structural schematic diagram of the road surface wind-blown sand movement state identification system of the present invention;

[0044] Figure 2 yes Figure 1 Bottom view of

[0045] Figure 3 is the dynamic friction coefficient curve;

[0046] Figure 4 The density of aeolian sand is 0.25 kg / m 2 Diagram of particle migration process.

[0047] In the above figure: 1 base plate; 101 supporting leg; 2 computer; 3 lifting plate; 4 electric push rod; 5 motor; 6 frequency modulation controller; 7 rotating shaft; 8 flywheel; 9 turntable; 901 rubber block; 902 spring sheet; 10 linear velocity sensor; 11 rotational velocity sensor; 12 torque sensor; 13 camera; 14 rutting plate; 15 wind-blown sand; 16 memory; 17 wireless serial port module; 18 spring; 19 spring damper. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0049] (I) Reference Figure 1-2 , a road aeolian sand movement state identification system proposed according to an embodiment of the content of the present invention comprises a base plate 1 and a computer 2; wherein, support legs 101 are symmetrically installed at the four corners of the bottom of the base plate 1; a lifting plate 3 is arranged above the base plate 1, and a lifting device is installed on the base plate 1, and the lifting device is used to drive the lifting plate 3 to move up and down; a frequency modulation controller 6 and a motor 5 are fixed on the lifting plate 3, respectively, and the signal output end of the frequency modulation controller 6 is electrically connected to the signal input end of the motor 5; the frequency modulation controller 6 is connected to the computer 2 through a wireless network; a rotating shaft 7 is vertically connected to the output shaft of the motor 5, and the lower end of the rotating shaft 7 passes through the base plate 1 and a flywheel 8 and a turntable 9 are arranged in sequence from top to bottom; a plurality of rubber blocks 901 are evenly installed on the bottom of the turntable 9 through a spring sheet 902; a linear speed sensor 10, a rotation speed sensor 11 and a torque sensor 12 are respectively arranged on the rotating shaft 7, and the linear speed sensor 10, the rotation speed sensor 11 and the torque sensor 12 are respectively connected to the computer 2 through a wireless network.

[0050] In the above embodiment, four stainless steel support legs 101 are symmetrically installed at the four corners of the bottom of the base plate 1. When the road aeolian sand movement state identification system of the present invention is used for testing, the support legs 101 can be placed on an actual road surface paved with aeolian sand 15 or on a rutting plate 14 for testing. The density of the aeolian sand 15 laid can be 0.25 kg / m 2 , 0.5kg / m 2 , 0.75kg / m 2 , 1kg / m 2 Etc., the density of the aeolian sand 15 can be adjusted artificially according to actual needs. The information obtained by the linear velocity sensor 10, the rotational speed sensor 11 and the torque sensor 12 can be directly transmitted to the computer 2, or first transmitted to the memory 16 for storage, and the memory 16 is then connected to the computer 2 through the wireless serial port module 17, and the obtained information is processed by the computer 2. The frequency modulation controller 6 is connected to the wireless serial port module 17 through a wire, and the wireless serial port module 17 is externally connected to the computer 2 through a wireless network; the computer 2 controls the working state of the frequency modulation controller 6 through the wireless network to achieve the precise control of the speed of the motor 5 by the frequency modulation controller 6, the output shaft of the motor 5 is fixedly connected to the rotating shaft 7 through a coupling, and the motor 5 drives the rotating shaft 7 to rotate at a constant speed (the rotating shaft 7 is used to simulate the transmission shaft of the vehicle), thereby driving the flywheel 8 and the turntable 9 fixedly connected to the rotating shaft 7 to rotate at the set speed (the flywheel 8 and the turntable 9 are used to simulate the rotation of the actual wheel), and can simulate different turntable initial speeds v on the turntable 9, as follows:

[0051]

[0052] Wherein, v is the initial speed of the turntable, km / h; f is the frequency of the frequency modulation controller, Hz; L is the circumference of the circle with the distance from the rotating shaft to the rubber block as the radius, m; p is the number of motor pole pairs; s is the slip rate. The initial speed v of the turntable is adjusted by the frequency modulation controller, and the real-time speed information of the turntable can be obtained through the speed sensor 11 installed on the rotating shaft 7.

[0053] The initial speed of the turntable 9 can be set to 5 gears, namely 20km / h, 30km / h, 40km / h, 50km / h, and 60km / h; when the speed of the turntable 9 reaches the set initial speed, the motor 5 stops working; the lifting device drives the lifting plate 3 to move downward, driving the rotating shaft 7 and the flywheel 8, the turntable 9 and the rubber block 901 to move downward, so that the rubber block 901 contacts the aeolian sand 15 on the road surface or the aeolian sand 15 on the rutting plate 14. At this moment, the linear velocity sensor 10 and the torque sensor 12 respectively collect the vertical falling speed information and torque value information of the rotating shaft 7 in real time, and the lifting device stops working at the same time. Due to the friction between the rubber block 901 and the road surface or the rutting plate 14, the turntable 9 gradually slows down and finally stops working, and the linear velocity sensor 10 and the torque sensor 12 stop data collection. The information collected by the linear velocity sensor 10 and the torque sensor 12 is transmitted to the memory 16 for storage, and the memory 16 transmits the acquired information to the computer 2. The computer 2 calculates the friction coefficient μ between the rubber block 901 and the aeolian sand 15 particles according to the information acquired by the linear velocity sensor 10 and the torque sensor 12, which is as follows:

[0054]

[0055] Wherein, M is the torque value collected by the torque sensor, N·m; m is the mass of the lifting plate and the falling bodies such as the flywheel, turntable, rubber block, and spring sheet, kg; L is the circumference of the circle with the distance from the rotating axis to the rubber block as the radius, m; The vertical falling velocity of the rotating shaft collected by the linear velocity sensor, m / s; is the inverse of acceleration.

[0056] In the road aeolian sand motion state identification system of the present invention, the rotation speed of the motor 5 can be accurately controlled by the frequency modulation controller 6, and the density of the aeolian sand 15 particles on the rutting plate 14 can be controlled, so the two variables of different turntable initial speeds and different aeolian sand densities can be simulated in the laboratory. Under the influence of the adhering medium such as aeolian sand 15, the road macrostructure is filled, resulting in the loss of structural depth and surface morphology, and the greater the density of the aeolian sand 15 particles between the tire and the road surface, the tire-road contact will gradually become the tire-sand-road three-way contact. When the turntable 9 drives the rubber block 901 to fall, the rubber block 901 will generate dynamic friction with the aeolian sand 15 particles until the static friction value is finally reached and the rotation stops. Under the action of dynamic friction, the particles will undergo mechanical behaviors such as embedding, compression, shearing, deformation, and crushing. With the increase of the density of aeolian sand and the initial speed of the turntable, the probability of migration and ejection of particles due to shearing increases. Data is collected through the torque sensor 12 and the linear speed sensor 10, and the friction coefficient of the road surface under different turntable initial speeds and aeolian sand densities is obtained after being processed by the computer 2; then, on the coordinate graph, the real-time turntable speed and the friction coefficient are used as the X and Y coordinates respectively, and the points are drawn and connected to obtain the change trend of the road surface friction coefficient value under different turntable initial speeds and aeolian sand densities, which is conducive to understanding the attenuation law of its anti-skid performance and further enriching the test results.

[0057] refer to Figure 1 According to one embodiment of the present invention, it further includes a camera 13, which is respectively arranged around the bottom plate 1, and is used to observe and record the migration and movement state of the aeolian sand 15 under different initial rotation speeds of the turntable and aeolian sand densities.

[0058] In the above embodiment, stainless steel support legs 101 are welded at the four corners of the bottom of the base plate 1, so that the camera 13 has a wide viewing angle to ensure the accuracy of the recording. The camera 13 uses four Sony FDR-AX100E high-speed cameras 13, and the four high-speed cameras 13 are connected to the computer 2 respectively. The frame rate of the high-speed camera is fixed at 60 frames / second, the effective pixel is 1 million, the maximum resolution is 1280×960, the size is 12μm×12μm, the pixel bit depth is 12bit, the exposure time is 0.0184ms, the exposure mode is frame exposure, the sensor type is CMOS sensor, and the color imaging is performed. Four high-speed cameras 13 are arranged 30 cm away from the four sides of the rutting plate 14 to be tested. The lens height is 6 cm. The shooting data can be connected to the computer 2 via a USB data cable. A single-frame image can be exported after being processed by Premiere CC to accurately observe the position and movement trend of the marked particles at a certain moment. Furthermore, a time interval can be framed for continuous observation and tracking, and finally the migration and movement state of the aeolian sand 15 particles when the rubber block 901 and the aeolian sand 15 particles are in contact with each other under different turntable initial rotation speeds and aeolian sand densities can be obtained.

[0059] refer to Figure 2 According to one embodiment of the present invention, the size of the rubber block 901 is 3 cm×3 cm×2 cm.

[0060] In the above embodiments, the size of the existing rubber block is generally 2cm×2cm×1cm, and the thickness is relatively thin, which makes it inconvenient to observe the migration and movement of the aeolian sand when the rubber block and the aeolian sand are in contact with each other through the camera. In order to prevent the rubber block 901 from generating torsional shear deformation during the operation of the device, three rubber blocks 901 with a size of 3cm×3cm×2cm are customized, with a Shore hardness of 65, connected to the turntable 9 through a spring sheet 902, and the central angle between the two is 120°; and the size of the rubber block of the present invention is adopted, which makes it convenient to observe the migration and movement of the aeolian sand 15 particles when the rubber block 901 and the aeolian sand 15 particles are in contact with each other through the camera.

[0061] refer to Figure 1 According to one embodiment of the present invention, the lifting device is an electric push rod 4; the electric push rod 4 is symmetrically installed on the base plate 1, and the upper end of the telescopic rod of the electric push rod 4 is horizontally fixedly connected to the lifting plate 3.

[0062] In the above embodiment, the lifting plate 3 is driven up and down by the electric push rod 4, thereby driving the rotating shaft 7, the flywheel 8, the turntable 9, the rubber block 901 fixedly connected to the lifting plate 3, the motor 5 and the frequency modulation controller 6 to move up and down together, so that when the turntable 9 reaches the set speed, the rubber block 901 can contact the aeolian sand 15 particles on the road surface or the rutting plate 14, which is convenient for subsequent tests.

[0063] According to one embodiment of the present invention, a spring 18 is connected between the flywheel 8 and the turntable 9 .

[0064] In the above embodiment, a balancing connection spring 18 is sandwiched between the flywheel 8 and the turntable 9 to keep the flywheel 8 and the turntable 9 in relative position.

[0065] refer to Figure 1 According to one embodiment of the present invention, a spring damper 19 is provided on the base plate 1 .

[0066] In the above embodiment, the spring damper 19 is used to reduce the vibration of the entire road surface aeolian sand movement state identification system during operation, thereby ensuring the test stability and the accuracy of data measurement.

[0067] refer to Figure 1 According to one embodiment of the present invention, it further includes a rutting plate 14, which is located below the supporting legs 101 of the base plate 1; aeolian sand 15 of different densities is placed on the rutting plate 14, and the aeolian sand 15 is marked with colors.

[0068] In the above embodiments, the rutting plate 14 is used to simulate the actual road surface structure. Different densities of aeolian sand 15 are laid on the rutting plate 14 to facilitate the test. The rutting plate 14 is covered with aeolian sand 15 particles marked by dyeing. The dyeing makes it easier for the camera 13 to observe and record the movement and migration trajectory of the aeolian sand 15.

[0069] (II) Taking the simulation of the wheel rutting plate 14 as an example, the method for using the system for identifying the movement state of particles of aeolian sand asphalt pavement of the present invention comprises the following steps:

[0070] Step 1: According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", make AC-13 graded asphalt mixture rutting plate specimens with a specimen size of 50cm*50cm*5cm.

[0071] Step 2: Place the support legs in the aeolian sand asphalt pavement particle motion state identification system on the rutting plate specimen, and lay the rutting plate specimens with a density of 0.25 kg / m 2 , 0.5kg / m 2 , 0.75kg / m 2 , 1.0kg / m 2 The aeolian sand of different density was measured and dyed; four cameras were placed 30 cm away from the test area around the rutting plate specimen, and the lens height of the four cameras was 6 cm, and the lenses were facing the surface of the aeolian sand particles.

[0072] Step 3, control the motor to drive the turntable to rotate at an initial speed of 40 km / h through the frequency modulation controller to ensure that the bottom surface of the rubber block on the turntable does not come into contact with the aeolian sand. At the same time, turn on the camera to continuously shoot the movement of the aeolian sand particles. The camera shoots the movement of the sand particles in the process of the rubber block falling from the initial speed until the speed drops to 0.

[0073] Step 4: After the turntable reaches the set initial speed of 40 km / h, the motor stops working, and the electric push rod controls the lifting plate to move downward, driving the rotating shaft, flywheel, turntable and rubber block to fall, so that the rubber block contacts the aeolian sand particles, and the electric push rod stops working. At this time, the torque sensor collects the torque value information of the rotating shaft, the linear speed sensor collects the vertical falling speed value information of the rotating shaft, and the rotation speed sensor collects the real-time rotation speed information of the turntable.

[0074] Step 5: Due to the friction between the rubber block and the rutting plate, the turntable gradually slows down and eventually stops. The torque sensor, linear velocity sensor, and rotational velocity sensor stop collecting data, and the camera stops shooting. Repeat the test three times at the same turntable initial speed and aeolian sand density. When the dynamic friction coefficient does not differ by more than 0.03, stop the test. This process becomes a set of tests. After each set of tests, use a high-power vacuum cleaner to clean the aeolian sand on the surface of the rutting plate.

[0075] Step 6: The computer calculates the friction coefficient μ between the rubber block and the aeolian sand particles based on the information collected by the torque sensor and the linear velocity sensor. The specific calculation process has been introduced in the structure of the aeolian sand asphalt pavement particle motion state identification system. On the coordinate graph, the real-time rotation speed and friction coefficient of the turntable collected by the rotation speed sensor are used as the X and Y coordinates to draw a graph of the road friction coefficient value under different aeolian sand densities, as shown in the figure below: Figure 3 shown.

[0076] Step 7: Use Premiere Pro 2018 software to convert the motion state of aeolian sand particles captured continuously by the camera into single-frame images, and analyze the motion behavior of aeolian sand particles based on the single-frame images, decomposing them into two particle motion flows, namely, particle flow Q ejected from the contact point between the rubber block and the asphalt pavement to be tested and particle flow Q L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R ; Then according to the particle flow Q ejected from the contact point between the rubber block and the asphalt road to be tested L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R Calculate the injection ratio IR L and recirculation ratio IR R , the results are shown in Table 1, as follows:

[0077]

[0078]

[0079] The particle flow velocity is estimated by the following formula

[0080]

[0081] Among them, n p is the number of pixels separating the particle positions between two given frames, and △t is the time interval between the two frames.

[0082] Table 1 Injection ratio IR of different aeolian sand density L and recirculation ratio IR R

[0083]

[0084] Figure 4 This is a 0.25kg / m image captured using Premiere Pro 2018 software. 2 Three single-frame images of aeolian sand density. The migration process of three aeolian sand particles can be observed in the marks in the picture.

[0085] Combined with the road friction coefficient value diagram and injection ratio IR under different wind-blown sand densities L and recirculation ratio IR R , analyze the movement behavior of sand particles with different densities and their impact on the anti-skid performance of the road surface; and analyze how the initial speed of the turntable affects the injection ratio IR L and recirculation ratio IR R .

[0086] It can be seen from the above results that the system and method for identifying the movement state of aeolian sand asphalt pavement particles of the present invention can display the dynamic migration behavior of aeolian sand from a microscopic perspective. The analysis of the dynamic migration behavior of aeolian sand is one of the important contents of analyzing the anti-skid performance of roads in desert areas. Therefore, the present invention is of great significance to the research on road driving safety in special areas.

[0087] Although the present invention has been described in detail in general terms and in specific embodiments in this specification, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A system for identifying the movement state of particles of aeolian sand asphalt pavement, characterized in that: The device comprises a base plate (1), a computer (2) and a camera (13); wherein the four corners of the bottom of the base plate (1) are symmetrically provided with support legs (101); a lifting plate (3) is arranged above the base plate (1), and a lifting device is installed on the base plate (1), and the lifting device is used to drive the lifting plate (3) to move up and down; The lifting plate (3) is respectively fixed with a frequency modulation controller (6) and a motor (5), and a signal output end of the frequency modulation controller (6) is electrically connected to a signal input end of the motor (5); the frequency modulation controller (6) is connected to the computer (2) via a wireless network; A rotating shaft (7) is vertically connected to the output shaft of the motor (5); the lower end of the rotating shaft (7) passes through the bottom plate (1) and is provided with a flywheel (8) and a turntable (9) in sequence from top to bottom; a plurality of rubber blocks (901) are evenly installed in the circumference of the bottom of the turntable (9) via a spring sheet (902); A linear speed sensor (10), a rotational speed sensor (11) and a torque sensor (12) are respectively arranged on the rotating shaft (7), and the linear speed sensor (10), the rotational speed sensor (11) and the torque sensor (12) are respectively connected to the computer (2) via a wireless network; The cameras (13) are respectively arranged around the bottom plate (1), and the cameras (13) are used to observe and record the migration and movement state of the aeolian sand (15) under different initial rotation speeds of the turntable and aeolian sand densities; The linear velocity sensor (10) is used to obtain vertical falling velocity information of the rotating shaft (7), and transmit the obtained vertical falling velocity information of the rotating shaft (7) to the computer (2); the torque sensor (12) is used to obtain torque value information, and transmit the obtained torque value information to the computer (2); the computer (2) calculates the friction coefficient between the rubber block (901) and the aeolian sand (15) particles based on the information obtained by the linear velocity sensor (10) and the torque sensor (12); The rotation speed sensor (11) is used to obtain real-time rotation speed information of the turntable (9).

2. The system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 1 is characterized in that: The size of the rubber block (901) is 3cm×3cm×2cm.

3. The system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 1 is characterized in that: The lifting device is an electric push rod (4); the electric push rod (4) is symmetrically mounted on the base plate (1), and the upper end of the telescopic rod of the electric push rod (4) is horizontally fixedly connected to the lifting plate (3).

4. The system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 1 is characterized in that: A spring damper (19) is arranged on the base plate (1).

5. The method for using the system for identifying the movement state of aeolian sand asphalt pavement particles according to claims 1 to 4, characterized in that: The following steps are involved: Step 1: Place the support legs in the aeolian sand asphalt pavement particle motion state recognition system on the asphalt pavement to be tested, and place cameras around the bottom plate respectively; Step 2, laying aeolian sand of different densities on the asphalt pavement to be tested; Step 3, control the motor to drive the turntable to rotate at different set initial speeds through the frequency modulation controller to ensure that the bottom surface of the rubber block on the turntable does not contact the aeolian sand, and at the same time, turn on the camera to continuously shoot the movement state of the aeolian sand particles; Step 4: After the turntable reaches the set initial speed, the motor stops working, and the electric push rod controls the lifting plate to move downward, driving the rotating shaft, flywheel, turntable and rubber block to fall, so that the rubber block contacts the aeolian sand particles, and the electric push rod stops working. At this time, the torque sensor collects the torque value information of the rotating shaft, the linear speed sensor collects the vertical falling speed value information of the rotating shaft, and the rotation speed sensor collects the real-time rotation speed information of the turntable; Step 5: Due to the friction between the rubber block and the asphalt road surface to be tested, the turntable gradually slows down and finally stops, the torque sensor, the linear speed sensor and the rotation speed sensor stop collecting data, and the camera stops shooting; Step 6: The computer calculates the friction coefficient μ between the rubber block and the aeolian sand particles based on the information collected by the torque sensor and the linear velocity sensor.

6. The method for using the system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 5 is characterized in that: In step 1, the asphalt pavement to be tested is a rutting plate or a physical asphalt pavement.

7. The method for using the system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 5, characterized in that: In step 6, the friction coefficient μ between the rubber block and the aeolian sand particles is calculated as follows: Wherein, M is the torque value of the rotating shaft collected by the torque sensor; m is the mass of the lifting plate, flywheel, turntable, rubber block and spring sheet; L is the circumference of the circle with the distance from the rotating shaft to the rubber block as the radius; It is the vertical falling speed value of the rotating shaft collected by the linear speed sensor; is the inverse of acceleration.

8. The method for using the system for identifying the movement state of aeolian sand asphalt pavement particles according to claim 5, characterized in that: The step 7 is also included, in which the motion state of the aeolian sand particles continuously photographed by the camera is converted into a single-frame image, and the particle flow Q ejected from the contact point between the rubber block and the asphalt pavement to be tested is determined according to the single-frame image. L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R ; According to the particle flow Q ejected from the contact point between the rubber block and the asphalt road to be tested L and the particle flow Q that is bounced by the rubber block and falls back to the asphalt road surface to be tested R Calculate the injection ratio IR L and recirculation ratio IR R , as follows: The particle flow velocity is estimated by the following formula Among them, n p is the number of pixels separating the particle positions between two given frames, and △t is the time interval between the two frames.

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