Construction method for testing vehicle wet-slippery braking road

Abstract

The invention discloses a construction method of a road for testing the slippery braking performance of a vehicle. The construction method comprises the steps of water feeding system installation, water return ditch construction, circular aggregate mix proportion design, mixture mixing, mixture paving, mixture rolling and quality control. The method is high in friction coefficient qualification rate, 100% coverage of the water film is controlled, the safety is high, the qualification rate of the friction coefficient, the flatness, the elevation, the water film thickness and the water film uniformity after the low-adhesion asphalt pavement is formed can be effectively guaranteed, and various technical indexes of the pavement meet design and test requirements.

Description

Technical Field

[0001] The present invention relates to the field of construction of vehicle test roads, and in particular to a construction method for a road for testing the wet skid braking performance of vehicles. Background Art

[0002] The annular asphalt wet skid test road surface of an automobile test field is used to test the performance of the whole vehicle and tires of an automobile, such as wet braking, wet stability control, and wet grip. However, the friction coefficient of a conventional asphalt road surface is ≥0.8 in a wet state, and the designed and tested friction coefficient of the annular asphalt wet skid test road surface of this test field is 0.5. It is impossible to meet the standard of a friction coefficient of 0.5 by using conventional asphalt mixture to pave the annular asphalt wet skid test road surface. The water film forming devices of the existing ABS test roads in test sites are mainly defined as the following two types: high-pressure water spraying type, medium-pressure flow spreading type, and low-pressure flooding type. The high-pressure water spraying type includes 4 different forms, namely rotary high-spray type, directional low-spray type, directional shower type, and directional atomization type. The low-pressure flooding type has only 1 kind of open-top overflowing low-pressure flooding type, which requires the lowest working pressure and mainly overflows as a whole at the water outlet when discharging water. The high-pressure water spraying type will generate high-pressure spray, affecting the accuracy of vehicle testing. Seriously, it will affect the driver's vision and increase the test safety. The low-pressure flooding type requires the lowest working pressure, resulting in uneven formation of the water film on the road surface and affecting the vehicle test results. Therefore, it is urgent to solve the problems that the traditional water supply system of the annular low-adhesion asphalt test road surface cannot ensure the uniformity of the water film on the road surface, the conventional process cannot ensure the construction quality of the annular low-adhesion asphalt test road surface, and the formed friction coefficient of the annular low-adhesion asphalt test road surface cannot be controlled. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method for a road for testing the wet skid braking performance of vehicles, so as to solve the problems that the traditional water supply system of the annular low-adhesion asphalt test road surface cannot ensure the uniformity of the water film on the road surface, the conventional process cannot ensure the construction quality of the annular low-adhesion asphalt test road surface, and the formed friction coefficient of the annular low-adhesion asphalt test road surface cannot be controlled. The construction method for a road for testing the wet skid braking performance of vehicles provided by this method has a high qualified rate of friction coefficient, 100% coverage of water film control, and high safety, and can effectively ensure the qualified rates of the friction coefficient, flatness, elevation, water film thickness, and water film uniformity of the low-adhesion asphalt road surface after forming, so that the technical indicators of the road surface meet the design and test requirements.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A construction method for a road for testing the wet skid braking performance of vehicles, comprising the following steps:

[0006] Step 1, Installation of the water supply system: The water supply system for the annular low-adhesion asphalt pavement uses high-density polyethylene (HDPE) pipes. The HDPE pipes are connected using the hot melt method, and the HDPE pipes are encapsulated with fine aggregate concrete; it includes preliminary preparation, cutting, centering, heating, switching, melt butt welding, cooling, and pressure drop to zero; then, the installation of piano key + "one-shaped" nozzles: Design and construct the piano key water supply curbstone, first connect the "one-shaped" nozzle with the L-shaped HDPE pipe, and the connection uses the hot melt method. When connecting, first install the nozzle fixing plate on the "one-shaped" nozzle;

[0007] Step 2, Construction of the return gutter: Conduct trial mixing according to the preliminary mix ratio to detect its consistency and determine the production mix ratio; then carry out the construction of the cushion mortar and the installation of the return gutter. First, lay a layer of fine aggregate concrete cushion on the top of the concrete encapsulation, and install the resin drainage gutter on the upper part of the fine aggregate concrete cushion. First, install the resin drainage gutter at the position with branch pipes, and then install the resin drainage gutter at the position without branch pipes;

[0008] Step 3, Design of the circular aggregate mix ratio: The circular aggregate uses 7mm - 11mm rain flower stones, and 3% of wood-based carbon fiber is added to the rain flower stones through mixing to form the circular aggregate;

[0009] Step 4, Mixing of the mixture: Dry mixing and wet mixing are carried out in sequence. After the first batch of the mixture is mixed, unload the mixture and observe the appearance and uniformity of the mixture; conduct temperature detection; the mixture should be uniform, without white and flower materials, without agglomeration or serious segregation of coarse and fine materials. Discard the abnormal mixture, and if there is no abnormality, mix it normally;

[0010] Step 5, Paving of the mixture: The paver should be adjusted to the best working condition, adjust the automatic material levelers at both ends of the spiral feeder, and make the opening of the material gate, the speed of the chain feeder, and the rotation speed of the spiral feeder match; the surface of the mixture in the spiral feeder should be slightly higher than 2 / 3 of the spiral feeder, so that the height of the mixture in front of the baffle of the screed is consistent within the full width to avoid segregation of the paving layer;

[0011] Step 6, Compaction of the mixture: During the compaction process, follow the principles of closely following, slow compaction, uniform speed, slow start and stop, moving forward and backward on the same straight line, and the compaction turns following the paving direction in a stepped shape. Orient the driving wheel of the roller towards the paver to avoid pushing and squeezing the mixture during compaction to form bulges; the hot joint plate follows the principle of compaction from low to high, compacting from the low side to the high side of the cross slope along the wheel axle, and the position where the roller turns back at both ends each time should be in a stepped shape, following the forward movement of the paver, so that the turning back points are not on the same cross section;

[0012] Step 7, Quality control: It includes flatness control, friction coefficient control, and water film thickness detection, and uses an adhesion coefficient adjustment vehicle, a flatness continuous monitoring instrument, and a water film thickness detector for quality control.

[0013] In Step 1, when switching, remove the heating plate, quickly make the two hot-melt end faces adhere to each other and apply pressure. To ensure the quality of the butt fusion, the shorter the switching period, the better. After reaching the heat absorption time, quickly open the machine and remove the heating plate. When removing the heating plate, avoid colliding with the molten end face. If a collision has occurred, the entire welding process should be restarted after the molten end face has completely cooled.

[0014] In Step 1, the prefabrication method of the piano-key water supply roadside stone is as follows: After the mold is processed and formed, first install the steel mesh in the mold, then pour C30 concrete. After pouring the concrete, use a small vibrating rod to vibrate it until it is dense. The density standard is that there are no obvious air bubbles on the surface of the concrete during vibration.

[0015] In Step 1, the installation method of the piano-key water supply roadside stone is as follows: Transport the qualified piano-key roadside stone to the site and use a crane for hoisting. When hoisting, the water spray nozzles of the piano-key water supply roadside stone should correspond one by one to the HDPE pipe joints of the water supply system.

[0016] In Step 2, the construction method of the cushion mortar is as follows: Before laying the cushion, first blow the floating dust, debris, and loose materials on the mixed water-stabilized base clean, and do not leave any debris that affects the quality. After the subgrade is cleaned, sprinkle water to moisten it. After the subgrade is cleaned, lay a fine aggregate concrete cushion. The laying height is controlled according to the elevation data calculated by reversing the designed elevation of the drainage ditch. After laying, use a special small rammer to ram it manually until there are no obvious voids. The fine aggregate concrete cushion cannot be laid too much at one time. It is necessary to lay the cushion while installing the linear drainage ditch.

[0017] After the resin drainage ditch in Step 2 is installed, use an electronic level to measure the inner edge of the drainage ditch at a spacing of 5m. When measuring, the elevation of the inner edge of the drainage ditch is controlled to be 2mm higher than the designed elevation, and the extra 1mm is used as the function of the water retaining plate.

[0018] In Step 5, when paving the mixture, for the one-way turning section of the annular low-adhesion asphalt pavement, the plate width division is based on the inner side as the main paving line and the outer side as the auxiliary line. The outer plate width is a gradually changing width, and the inner side is a fixed width, which corresponds to the paver. For the one-way turning section, 1 fixed-width paver and 1 movable-width paver are used for tandem operation. The adjustable range of the plate width of the movable-width paver is 4.2 - 5.6m, and the fixed width of the plate width of the fixed-width paver is 3.8m. During the paving process, the movable-width paver travels in front, and the fixed-width paver travels behind. After the gradually changing width paving is completed, it drives out of the paving area, and finally the fixed-width paver completes the main line paving. There is no cold joint in the one-way turning section, and all are hot joints.

[0019] In Step 5, the S-shaped double turning is a transition from an inner-low and outer-high flat curve to an outer-high and inner-low flat curve. During paving, an adjustable screed paver is used for paving. During the paving process, the operators on both sides of the paver adjust the error of the screed's lifting and lowering according to the modified control table in real time to ensure the smoothness of the curve in the transition section of the vertical and horizontal curves.

[0020] In Step 7, a road surface friction coefficient adjustment vehicle is used to control the friction coefficient. The road surface friction coefficient adjustment vehicle mainly consists of a horizontally stable main beam, a hydraulic cylinder, a counterweight beam, a vertical column, a grinding rubber wheel, a traveling wheel, a towing triangle, a tractor, etc.

[0021] In Step 7, a water film thickness detector is used for water film thickness detection. One point is measured per 10 ㎡ on the formed road surface. The requirements for measuring the water film thickness are: 0.5mm ≤ h ≤ 1.5mm, and the qualification rate is 97.9%.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) High friction coefficient qualification rate: The annular asphalt wet and slippery test road surface uses new smooth round aggregates with a particle size of 7mm - 11mm. After the road surface is paved and formed and then processed by the road surface friction coefficient adjustment vehicle, the surface friction coefficient is lower than that of the road surface formed by granite or basalt. By applying new raw materials, the friction coefficient qualification rate of the annular low-adhesion asphalt road surface is ensured.

[0024] (2) 100% coverage of water film control: The annular asphalt wet and slippery test road surface adopts a spray and diffusion combination system of piano keys + "one-shaped" nozzles to supply water to the formed low-adhesion asphalt road surface, so that the uniformity and coverage rate of the test water film on the road surface meet the design and test requirements. A water supply system of piano keys + "one-shaped" nozzles is installed on the higher side of the test road surface elevation. Through the fan-shaped water supply of the piano keys, the formed low-adhesion asphalt road surface is diffusely supplied with water to achieve the requirement that the water film on the road surface is within ±2mm and the water film coverage rate reaches 100%. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the piano key water supply curbstone of the present invention. Detailed Embodiments

[0026] To make the design concept and method of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Refer to Figure 1 , a construction method for a drainage side ditch of a test site, including the following steps:

[0028] Step 1, Installation of the water supply system: The water supply system for the annular low-adhesion asphalt pavement uses high-density polyethylene (HDPE) pipes. The HDPE pipes are connected using the hot melt method and are encapsulated with fine aggregate concrete. First, during the preliminary preparation: Connect the power supply to each component of the welding machine. It is necessary to use alternating current with a voltage of 220V and a frequency of 50Hz, with the voltage variation within ±10%. The power supply should have a grounding wire; at the same time, ensure that the surface of the heating plate is clean and free of scratches. Connect the pump station and the frame with hydraulic wires. Before connection, check and clean the dirt at the joints to prevent dirt from entering the hydraulic system and damaging the hydraulic components; after connecting the hydraulic wires, lock the joint part to prevent the joint from being opened during high-pressure operation. Enter the welding data according to the selected working mode: diameter; wall thickness or SDR value; temperature setting of the heating plate; welder code. Clamp the PE pipe or fitting in a flat position on the butt welding machine, leaving a cutting allowance of 10 - 20mm. Select the appropriate chuck fixture according to the welded PE pipe and fitting, and clamp the pipe to prepare for cutting. Second, cutting: Cut the impurities and oxide layers on the end faces of the welded pipe sections and fittings to ensure that the two butt end faces are flat, smooth, and free of impurities. Open the frame, insert the milling cutter, rotate the locking knob to fix the milling cutter on the frame. First, turn on the power switch of the milling cutter, then close the two ends of the pipe and apply appropriate pressure until continuous chips appear at both ends (the chip thickness is 0.5 - 10mm, and the chip thickness can be adjusted by adjusting the height of the milling cutter blades). Remove the pressure, wait for a moment, then retract the movable frame and turn off the power of the milling cutter; when starting the pump station, it should be done when the direction control handle is in the middle position, and it is strictly prohibited to start under high pressure. Start the milling cutter, close the fixture, and cut the end faces of the pipe and fitting. When continuous cutting is formed, reduce the pressure, open the fixture, and turn off the milling cutter. This process must be carried out in the order of first reducing the pressure, then opening the fixture, and finally turning off the milling cutter. Remove the milling cutter, close the fixture, close the two ends of the pipe, and check the alignment of the two ends (the misalignment amount at both ends of the pipe cannot exceed 10% of the wall thickness, which can be improved by adjusting the straightness of the pipe and tightening or loosening the chuck; check the gap between the two ends of the PE pipe. The gap amount shall not be greater than 0.3mm (for pipes with a diameter of de225mm or less). If the requirements are not met, re-mill until the requirements are satisfied. When removing the milling cutter from the frame, avoid the milling cutter colliding with the end face. If it has occurred, re-mill; do not touch the milled end face with your hand or let it be contaminated by oil or dirt. Third, centering: Check the coaxiality of the PE pipe (the maximum misalignment amount is 10% of the wall thickness). When the gap and misalignment amount between the two end faces do not meet the requirements, re-clamp and mill the workpiece to be welded, and only after passing the inspection can the next step be carried out. Fourth, heating: Check whether the temperature of the heating plate is appropriate, 210°C - 230°C, and it is appropriate that the molten length at both end faces is 1 - 2mm. The red indicator light on the heating plate should be on or flashing. After the red indicator light on the heating plate first lights up, wait for another 10 minutes before use to make the temperature of the entire heating plate uniform. Test the dragging pressure P0 of the system and record it.The dragging pressure of each welded joint needs to be measured; when the dragging pressure is too high, methods such as padding short pipes can be used to solve it. Place the heating plate at an appropriate temperature on the frame, close the fixture, and set the system pressure P1. P1 = P0 + joint pressure. When the protrusions between the PE pipes (pipe fittings) are uniform and the height reaches the requirement, lower the pressure to approximately the dragging pressure, and at the same time press the endothermic timing button to start recording the endothermic time. P2 = P0 + endothermic pressure (the endothermic pressure is almost zero). If the heating time is too short, it is easy to cause uneven heating of the pipe fittings, resulting in difficulty in aligning the ports; if the heating time is too long, the pipe fittings will be melted as a whole, and too much colloidal substance will appear and flow away. Fifth, switching. Remove the heating plate and quickly make the two hot-melt end faces stick together and apply pressure. To ensure the quality of the fusion butt joint, the shorter the switching cycle, the better. After reaching the endothermic time, quickly open the machine tool and remove the heating plate. When removing the heating plate, avoid colliding with the molten end face; if it has occurred, after the melted end face has completely cooled, restart the entire welding process. Sixth, fusion butt joint. Butt joint is the key to welding. The butt joint process should always be carried out under the molten pressure, and the bead width should be appropriate at 1 - 2 mm. Seventh, cooling. Keep the butt joint pressure unchanged and let the joint cool slowly. The cooling time is determined by feeling that the bead is hard when touched by hand and there is no heat. Quickly close the fixture, and within the specified time, quickly adjust the pressure to P3, and at the same time press the timer to record the cooling time. P3 = P0 + cooling pressure. When the pressure is increased after the fixture is closed, the pressure should be increased evenly, not too fast or too slow, and it should be completed within the specified time; otherwise, false welding or loose welding may occur, and this pressure should be maintained until the welded joint is completely cooled. Eighth, pressure drop to zero. After the butt joint is completed and the cooling time is reached, drop the pressure to zero, open the fixture, remove the welded pipe (pipe fitting), move the butt joint machine, and prepare for the connection of the next interface. Be sure to drop the system pressure to zero before removing the pipe; if the welding machine needs to be moved, remove the hydraulic wire and promptly do a good job in dust prevention at the joint.

[0029] Installation of piano keys + "one - character" nozzles: First, the design of the piano - key water supply curbstone. The outline dimensions of the "piano - key" water supply curbstone design (total length 99 cm, width 57 cm, front - end thickness 13 cm, rear - end thickness 18 cm) are a total length of 99 cm, width 57 cm, and thickness 18 cm. The nozzle outlet is square, and the height of the water - retaining surface is 4 cm. After construction, there will be a 5 - cm step - height difference between the test road and its adjacent road. Second, the construction of the piano - key water supply curbstone, mold production: The total length of the piano - key - shaped water supply curbstone is 99 cm, width 57 cm, and thickness 18 cm. The nozzle outlet is square, and the height of the water - retaining surface is 4 cm. After construction, there will be a 5 - cm step - height difference between the test road and its adjacent road. The outlet changes from a square to an eight - character - shaped opening with a 106° angle, and the front - end thickness is 5 cm less than the rear - end thickness. The surface is in a slope form. After construction, there will be a 5 - cm step - height difference between the test road and its adjacent road. Prefabrication of the piano - key water supply curbstone: After the mold is processed and formed, first install a steel - wire mesh in the mold, and then pour C30 concrete. After pouring the concrete, use a small vibrating rod to vibrate it densely. The densification standard is that there are no obvious air bubbles on the concrete surface during vibration. After vibration, cure the formed piano - key water supply curbstone for 7 days, and demold it after the curing period expires. Third, the installation of the piano - key water supply curbstone. Transport the qualified piano - key curbstone to the site and use a crane for hoisting. When hoisting, the water - spraying openings of the piano - key water supply curbstone should correspond one - by - one with the HDPE pipe joints of the water - supply system. Fourth, the installation of the "one - character" nozzle. First, connect the "one - character" nozzle with the L - shaped HDPE pipe. The connection uses the hot - melt method. When connecting, first install a nozzle fixing plate on the "one - character" nozzle. The nozzle fixing plate is made of 2 - mm - thick galvanized steel plate.

[0030] Step 2, Construction of the return water channel: First, design the mix ratio of fine aggregate concrete. Conduct trial mixing according to the preliminary mix ratio to detect its consistency. If the indicators meet the design requirements, this mix ratio is the reference mix ratio. After trial mixing, when the water consumption and water-cement ratio are determined, conduct trial mixing of the other two mix ratios. Adjust the water-cement ratio by ±0.05 based on the determined water consumption for trial mixing. After trial mixing, determine the production mix ratio. According to the mix ratio, conduct trial adaptation of the concrete and pour it into a 150*150*150 test mold, and cure it under standard conditions. Measure its 7-day strength and 28-day strength respectively. According to the strength results of the trial mixing, select a water-cement ratio of 0.39 as the construction mix ratio. Second, construct the cushion mortar. Before laying the cushion, blow the floating dust, sundries, and loose materials on the cement stabilized base clean, and no sundries affecting the quality shall be left. After the underlying layer is cleaned, sprinkle water to moisten it. After the underlying layer is cleaned, lay the fine aggregate concrete cushion. The laying height is controlled according to the elevation data calculated by reversing the design elevation of the drainage ditch. After laying, use a special small tamper board manually to tamp it until there are no obvious voids. The fine aggregate concrete cushion cannot be laid too much at one time. It is necessary to lay the cushion while installing the linear drainage ditch. Third, install the return water channel. First, lay a layer of fine aggregate concrete cushion on the top of the concrete encapsulation. Install the resin drainage ditch on the upper part of the fine aggregate concrete cushion. First install the resin drainage ditch at the position with branch pipes, and then install the resin drainage ditch at the position without branch pipes. After installing the resin drainage ditch, use an electronic level to conduct leveling measurement on the inner edge of the drainage ditch at an interval of 5m. When measuring, control the elevation of the inner edge of the drainage ditch to be 2mm higher than the design elevation, and the extra 1mm is used as the function of the water retaining plate.

[0031] Step 3, Design of the mix ratio of round aggregates: The round aggregates are designed with a mix ratio: The round aggregates use 7mm-11mm Yuhua stones, and add 3% of wood-based carbon fiber to the Yuhua stones through mixing to form round aggregates;

[0032] Step 4, Mixing of the mixture: Due to the particularity of this mixture, the mixing time is different from that of other mixtures. The dry mixing time is 10s, and the wet mixing time is 40s. After the first batch of the mixture is mixed, unload the mixture and observe the appearance and uniformity of the mixture; conduct temperature detection; the mixture should be uniform, without white and flower materials, no agglomeration or serious separation of coarse and fine materials. Discard the abnormal mixture and mix normally if there is no abnormality.

[0033] Step 5, Mix paving: The paver should be adjusted to the best working condition, the automatic levelers at both ends of the spiral feeder should be adjusted, and the opening of the material gate, the speed of the chain feeder, and the rotation speed of the spiral feeder should be matched. The surface of the mixture in the spiral feeder should be slightly higher than 2 / 3 of the spiral feeder, so that the height of the mixture in front of the baffle of the screed is consistent within the full width to avoid segregation of the paving layer. During the paving process, it should be paved slowly, evenly, and continuously. When the paving thickness increases, the paver must be adjusted. The paving of the mixture should be carried out at a reasonable speed and adjusted reasonably according to the mixing capacity of the mixing plant, generally not exceeding 2 m / min, and paved slowly, evenly, and continuously. For the one-way turning section of the circular low-adhesion asphalt pavement, the paving main line is on the inner side and the auxiliary line is on the outer side within the width division of the slab. The width of the outer slab is a gradually changing width, and the inner side is a fixed width, corresponding to the paver. One fixed paver and one movable paver are used in a echelon operation at the one-way turning section. The adjustable width range of the movable paver is 4.2 - 5.6 m, and the fixed width of the fixed paver is 3.8 m. During the paving process, the movable paver travels in front and the fixed paver travels behind. After the gradually changing width paving is completed, it drives out of the paving area, and finally the fixed paver completes the main line paving. No cold joints are set at the one-way turning section, and all are hot joints. For the S-shaped two-way turning section, it is mostly transitioned from an inner-low and outer-high horizontal curve with a radius of 5 m - 25 m to an outer-high and inner-low horizontal curve with a radius of 25 m - 78 m. The slope rate changes from +1.5% to 0%, and then from 0% to -1.5%. During the paving of this area, one movable paver is used for paving. During the paving process, the operators on both sides of the paver adjust the lifting error of the screed according to the control table at all times to ensure the smoothness of the curve in the transition section of the horizontal / vertical curve.

[0034] Step 6, Mix compaction: Designate a special person to manage the compaction construction. Use a temperature gun to detect the compaction temperature. The internal temperature of the mixture at the start of compaction should not be lower than 165 °C, and the surface temperature at the end of compaction should not be lower than 100 °C. In case of any abnormal situation, immediately notify the on-site person in charge for timely handling; mark the paragraphs of initial compaction, re-compaction, and final compaction for easy identification by the driver; check the roller combination, compaction passes, and compaction speed to avoid over-compaction and missed compaction. During the compaction process, follow the principles of closely following and slowly compressing, uniform speed, slow start and stop, moving forward and backward on the same straight line, and the compaction turns following the paving direction in a stepped shape. Point the driving wheel of the roller towards the paver to avoid pushing and squeezing the mixture during compaction to form bumps. The hot joint plate follows the principle of compressing from low to high, and compresses and densifies from the low side to the high side of the cross slope. The position where the roller turns back at both ends each time should be stepped, and as the paver advances forward, the turning-back points are not on the same cross-section. During the compaction of the cold joint, first compact from the formed road surface to the newly paved road surface, following the principles of from low to high, first light then heavy, and first weak vibration then strong vibration. The vibration of the steel wheel roller overlaps 20 cm each time, and the static pressure overlaps 1 / 3 of the wheel width. Keep a uniform speed during compaction and prohibit staying and turning on the newly paved mixture.

[0035] Step 7, Quality Control: First, flatness control: For flatness detection, a "3m" continuous rolling detection device is used. When using this device for flatness detection, first install the device. The traveling wheels are installed below the connecting fixed frame, and the rolling induction wheel is installed in the middle position between the two traveling wheel axles. Before use, place the device on a special leveling plate for leveling. The leveling plate ensures absolute flatness. Manually place the detection pointer at the zero position and fix it with bolts below to ensure that the traveling wheels and the rolling detection wheel are on the same horizontal plane. Hold the handles of the direction control rods tightly with both hands and push the device to move smoothly on the road surface. According to the flatness of the road surface, the rolling induction wheel rises and falls, driving the detection pointer to swing, and the swing amplitude is presented on the display dial. When the rolling induction wheel encounters a raised road surface during travel, the detection pointer will indicate a positive value; when the rolling induction wheel encounters a sunken road surface during travel, the detection pointer will indicate a negative value. Read and record according to the scale pointed by the tip of the pointer. During the reading process, look directly at the instrument display panel to avoid reading errors caused by angle problems. After compaction, pull the detection instrument by hand. Due to the unevenness of the road surface, it will drive the up and down movement of the small wheels and drive the measuring rod to slide up and down in the small hole groove of the displacement sensor, and then determine the flatness of the asphalt road surface by combining the magnitude output by the sensor. Sort out the data, find the areas with larger flatness, analyze the reasons, and avoid recurrence next time. Second, friction coefficient control. The road surface friction coefficient adjustment vehicle mainly consists of a horizontally stable main beam, a hydraulic cylinder, a counterweight beam, a vertical column, a grinding rubber wheel, a traveling wheel, a towing triangle, a tractor, etc. The horizontally stable main beam and the counterweight beam are welded with 250*200*3mm channel steel, with a frame length of 250cm and a width of 90cm. The vertical column is a square steel with a wall thickness of 3mm and is perpendicularly welded to the horizontally stable frame. The height of the vertical column is 148cm. The vertical column is the vertical support for fixing the hydraulic cylinder, and its function is to cooperate with the telescopic height of the hydraulic cylinder for the traveling wheel and the grinding rubber wheel. The counterweight beam is welded above the horizontally stable frame with 2 square steels of 200*200*3mm. The counterweight beam is parallel to the traveling wheel bearing, and the length of the counterweight beam is 315cm. The hydraulic cylinder and hydraulic oil pipes. The hydraulic cylinder uses a Φ40 secondary jack column, with a maximum lifting speed of 400mm / s, a pressure resistance of 31.5Mpa, and a minimum starting pressure of 0.3Mpa. 2 hydraulic oil pipes are connected to each hydraulic cylinder, and the hydraulic oil pipes are special hoses with a diameter of Φ1.5cm. The traveling wheel and the grinding rubber wheel. The traveling wheel uses a Φ60cm conventional tire, and the grinding rubber wheel uses a Φ40cm conventional tire. The grinding rubber wheels are grouped in sets of 3, with a total of 4 sets. The bearings of each set of grinding rubber wheels form a 30° angle with the horizontally stable main beam. The towing triangle is welded and formed with 150*150*3mm square steel, and the welding inner angle forms a 60° angle with the horizontally stable main beam. The tractor selects a high-power tractor head, and the tractor needs to have a special hydraulic control system.There are 2 traveling wheels and 12 grinding rubber wheels installed at the lower part of the road surface friction coefficient adjustment vehicle. When grinding, the vehicle moves forward using the grinding rubber wheels, and after the operation is completed, it moves using the traveling wheels. The road surface friction coefficient adjustment vehicle has a remarkable use effect, is convenient to operate, and has a small cost investment; it improves the quality problem of local unqualified friction coefficient of asphalt pavement, avoids the cost input during conventional treatment, and improves the qualified rate of the pavement quality after forming. Through comprehensive analysis of the frame structure and materials of the friction vehicle, by increasing or decreasing the counterweight of the friction vehicle, the friction coefficient of the road surface is accurately controlled, effectively solving the problem that the grinding coefficient is uncontrollable. Third, for the water film thickness detection, use a water film detector to measure 1 point per 10 ㎡ on the formed road surface. The requirements for measuring the water film thickness are: 0.5mm ≤ h ≤ 1.5mm, and the qualified rate is 97.9%.

[0036] The above details the solutions provided by the embodiments of the present invention. For general designers in the field, there will be changes in the specific implementation methods and application scopes according to the ideas of the embodiments of the present invention. The scope to be protected by the present invention is not limited to the technical solutions mentioned in this embodiment. Any technical solution inspired by the present invention falls within the protection scope of the present invention.

Claims

1. A construction method for testing the wet braking performance of a vehicle, comprising the following steps: Step 1, water supply system installation: The circular low-adhesion asphalt pavement water supply system uses high-density polyethylene HDPE pipes. The HDPE pipes are connected by hot-melt method and are encapsulated with fine stone concrete; including preliminary preparation, cutting, centering, heating, switching, melting docking, cooling and pressure drop to zero; then install the piano key + "one-shaped" sprinkler: design, construct and install the piano key water supply curbstone, first connect the "one-shaped" sprinkler with the L-shaped HDPE pipe, and use hot-melt method to connect. When connecting, first install the sprinkler fixing plate on the "one-shaped" sprinkler; Step 2: Construction of water return ditch: Test the consistency of the preliminary mix ratio to determine the production mix ratio; then carry out the construction of cushion mortar and installation of water return ditch. First, lay a layer of fine stone concrete cushion on the top of the concrete encapsulation, and install the resin drainage ditch on the top of the fine stone concrete cushion. First, install the resin drainage ditch with branch pipe position, and then install the resin drainage ditch without branch pipe position. Step 3: Round aggregate mix design: The round aggregate is made of 7mm-11mm Yuhua stone, and 3% of wood carbon fiber is added to the Yuhua stone and mixed to form round aggregate; Step 4: Mixing the mixture: dry mixing and wet mixing are carried out in sequence. After the first batch of mixture is mixed, unload the mixture to observe the appearance and uniformity of the mixture; temperature detection; the mixture should be uniform and consistent, without white material, no agglomeration or serious separation of coarse and fine materials. Abnormal mixtures should be discarded, and normal mixing should be carried out if there are no abnormalities; Step 5: Spreading the mixture: The paver should be adjusted to the best working state, the automatic level gauges at both ends of the spiral distributor should be adjusted, and the material door opening, the speed of the chain plate feeder and the rotation speed of the spiral distributor should match each other; the surface of the mixture in the spiral distributor should be slightly higher than 2 / 3 of the spiral distributor, so that the height of the mixture in front of the baffle of the screed plate is consistent throughout the width to avoid segregation of the paving layer; Step 6, rolling of the mixture: During the rolling process, the principles of close follow-up slow rolling, uniform speed, slow start and slow stop, forward and backward on the same straight line, and rolling back in a step-shaped manner along the paving direction should be implemented. The driving wheel of the roller should be directed toward the paver to avoid squeezing the mixture and causing congestion during the rolling process; the hot-joint plate should follow the principle of rolling from low to high, and the wheel axle should roll closely from the low side of the cross slope to the high side. The position where the roller turns back from both ends each time should be in a step-shaped manner, and as the paver moves forward, the turning point should not be on the same cross section; Step seven, quality control: including flatness control, friction coefficient control and water film thickness detection, using adhesion coefficient adjustment vehicle, flatness continuous monitoring instrument and water film thickness detector for quality control.

2. A construction method for testing the wet braking performance of a vehicle according to claim 1, characterized in that: In step one, when switching, remove the heating plate, quickly let the two hot-melt end faces stick together and pressurize them. To ensure the quality of fusion butt joint, the switching cycle should be as short as possible. After the endothermic time is reached, quickly open the machine and remove the heating plate. When removing the heating plate, avoid collision with the molten end face. If it has occurred, restart the entire welding process after the melted end face has completely cooled down.

3. A construction method for testing the wet braking performance of a vehicle according to claim 1, characterized in that: In step one, the piano key water curb is prefabricated in the following way: after the mold is processed and formed, the steel mesh is first installed in the mold, and then C30 concrete is poured. After pouring the concrete, a small vibrator is used to vibrate and compact it. The compaction standard is that no obvious bubbles emerge from the surface of the concrete during vibration.

4. A construction method for testing the wet braking performance of a vehicle according to claim 3, characterized in that: In step one, the piano key water supply curb is installed as follows: the qualified piano key curb is transported to the site and hoisted by a crane. During hoisting, the water outlet of the piano key water supply curb must correspond one by one to the HDPE pipe joint of the water supply system.

5. The method for constructing a road for testing vehicle slippery braking performance according to claim 1, characterized in that: In step two, the cushion layer mortar construction method is: before laying the cushion layer, the floating dust, debris and loose materials on the mixed water stabilized base layer must be blown away, and no debris that affects the quality must be left. After the lower bearing layer is cleaned, sprinkle water to moisten it; after the lower bearing layer is cleaned, the fine stone concrete cushion layer is laid, and the laying height is controlled according to the elevation data after inverse calculation of the design elevation of the drainage ditch. After laying, it is manually compacted with a special small tamping board until there are no obvious gaps; the fine stone concrete cushion layer cannot be laid too much at one time, and the linear drainage ditch must be installed while the cushion layer is spread.

6. A construction method for testing the wet braking performance of vehicles according to claim 1, characterized in that: After the resin drainage ditch in step 2 is installed, use an electronic level to measure the inner edge of the drainage ditch at intervals of 5m. During measurement, the elevation of the inner edge of the drainage ditch is controlled to be 2mm higher than the design elevation, and the excess 1mm serves as a water retaining plate.

7. The method for constructing a road for testing vehicle slippery braking performance according to claim 1, characterized in that: In step five, when paving the mixture, the slab width at the one-way turn of the circular low-adhesion asphalt pavement is divided into the inner side as the main paving line and the outer side as the auxiliary line. The outer slab width is a gradual width and the inner side is a fixed width. The width corresponds to the paver. At the one-way turn, one fixed slab paver and one movable slab paver are used in a echelon operation. The slab width adjustment range of the movable slab paver is 4.2-5.6m, and the fixed slab paver slab width is 3.8m. During the paving process, the movable slab is driven in front and the fixed slab paver is driven in the back. After the gradual width paving is completed, it leaves the paving area and is finally paved by the fixed slab paver for the main line. No cold joints are set at the one-way turn, and all are hot joints.

8. A method for constructing a road for testing vehicle slippery braking performance according to claim 7, characterized in that: In step five, the S-shaped two-way turning section is a transition from a flat curve with a low inner side and a high outer side to a flat curve with a high outer side and a low inner side. A movable plate paver is used for paving. During the paving process, the operators on both sides of the paver adjust the ironing plate take-off and lowering errors according to the control table to ensure the smoothness of the transition section between the flat and vertical curves.

9. A construction method for testing the wet braking performance of vehicles according to claim 8, characterized in that: In step seven, the friction coefficient is controlled by a road friction coefficient adjusting vehicle, which is mainly composed of a horizontal stable main beam, a hydraulic cylinder, a counterweight beam, a vertical column, a grinding rubber wheel, a traveling wheel, a traction triangle, a traction vehicle, etc.

10. The method for constructing a road for testing vehicle slippery braking performance according to claim 1, characterized in that: In step seven, a water film detector is used to detect the water film thickness. One point is measured every 10 m2 on the formed road surface. The water film thickness measurement requirement is: 0.5mm≤h≤1.5mm, and the pass rate is 97.9%.

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