A test device and method for measuring the maximum drainage capacity of porous asphalt concrete

Abstract

The present invention discloses a test device and method for measuring the maximum drainage capacity of porous asphalt concrete, the test device comprising a work cabinet, a water supply system, a specimen support mechanism, and a collection and weighing component. The test device of the present invention can use a porous asphalt concrete specimen formed indoors for testing, and under the conditions of simulating different rainfall intensities and transverse and longitudinal slopes of the road surface, respectively collect the drainage on the surface and inside of the porous asphalt concrete specimen, and use a line graph of the relationship between the drainage on the surface and inside of the specimen and the water supply flow rate to analyze and determine the maximum drainage capacity of the specimen, so as to provide a reasonable warning interval for the use of drainage pavement by road departments in rainfall, especially in heavy rainfall weather.

Description

Technical Field

[0001] The invention relates to a test device and a method for measuring the maximum drainage capacity of porous asphalt concrete, belonging to the field of road engineering. Technical Background

[0002] Drainage asphalt pavement has been widely studied and used in recent years due to its large-void structural characteristics, which bring about good drainage, anti-skid and noise reduction performance. At the same time, as the people's demand for travel quality and safety continues to increase, in order to ensure driving safety on drainage pavement in heavy rainfall weather, it is of great practical significance to be able to reasonably measure the maximum drainage capacity of drainage asphalt pavement and provide traffic control departments with early warning interval standards.

[0003] However, most of the current tests on the drainage performance of drainage asphalt pavements ignore the importance of determining the maximum drainage capacity of the pavement, and even directly use the rainfall intensity when there is no obvious water accumulation on the road surface as the maximum drainage capacity of the drainage pavement. This method is subjective and has a great impact on the test results. Secondly, many indoor tests ignore the influence of longitudinal and transverse slopes on the drainage performance of porous asphalt concrete specimens, which is one of the reasons why there is a significant difference between indoor simulation tests and actual pavement test results. In addition, existing equipment and methods do not fit the actual situation that drainage asphalt pavements will drain water from both the surface and the inside when encountering rainfall, especially heavy rainfall. Therefore, the pavement drainage is divided into surface and internal drainage, and this is used as the basis for analysis. Obtaining indicators such as the maximum drainage capacity of the pavement through reasonable test methods and analysis means is of great significance for driving safety and the optimization of the early design of drainage asphalt pavements.

[0004] Based on this, it is necessary to design a set of relevant test equipment and methods, which can consider the drainage of specimens into two aspects: surface drainage and internal drainage, and simulate different rainfall intensities and longitudinal and transverse slopes of the road surface, so as to make the indoor test environment as close as possible to the actual service conditions of the drainage pavement, and use reasonable test and analysis methods to calculate the maximum drainage capacity of porous asphalt concrete. Summary of the invention

[0005] Purpose of the invention: In view of the problems and shortcomings in the prior art, the purpose of the present invention is to provide a test device and method for measuring the maximum drainage capacity of porous asphalt concrete.

[0006] Technical solution: A test device for measuring the maximum drainage capacity of porous asphalt concrete, characterized by: comprising a working cabinet, a water supply system, a collection and weighing component, and a specimen supporting mechanism;

[0007] A first water collecting tank is provided inside the working cabinet, and a water pump of the water supply system is placed inside the first water collecting tank;

[0008] The collecting and weighing assembly comprises a second water collecting tank placed above the working cabinet, a third water collecting tank placed inside the second water collecting tank, and a first weighing instrument located below the third water collecting tank; a second control valve port is provided at the bottom of the second water collecting tank; a fourth water collecting tank and a second weighing instrument located below the fourth water collecting tank are provided below the second control valve port; the fourth water collecting tank and the second weighing instrument are located inside the working cabinet;

[0009] The specimen supporting mechanism is placed in the second water collecting tank and is located directly below the nozzle of the water supply system. The specimen supporting mechanism includes a specimen supporting frame, a large square frame located directly below the specimen supporting frame, a drainage channel and supporting legs arranged at the bottom of the large square frame, and the water outlet of the drainage channel is located above the third water collecting tank and is provided with a first control valve port;

[0010] The specimen support frame comprises a small square frame and a bottom plate located below the small square frame, the small square frame and the bottom plate are connected via a spring, and a limiting plate is movably connected to the small square frame;

[0011] The square small frame and the square large frame are connected by oblique guide plates on all sides; the outer edge of the bottom of the oblique guide plate is located in the second water collecting tank.

[0012] The technical solution further defined in the present invention is that a test piece placement area is provided below the second weighing instrument.

[0013] Preferably, a third control valve port is provided at the bottom of the third water collecting tank, a fourth control valve port is provided at the bottom of the fourth water collecting tank, and a water outlet of the fourth control valve port is located above the first water collecting tank.

[0014] Preferably, the water supply system includes the water pump, the water pipe and the nozzle, the water pipe and the nozzle are fixed by a support frame, the support frame is provided with a power switch, a water supply switch and a flow digital display controller, and the flow digital display controller is connected to the water pipe.

[0015] Preferably, the effective rainfall area of ​​the nozzle is less than 300mm×300mm, and the horizontal dimension of the inner frame of the small square frame is 300mm×300mm.

[0016] The present invention also relates to a method for measuring the drainage performance of porous asphalt concrete, using the above-mentioned test device, the method comprises the following steps:

[0017] (1) Place the specimen in the specimen support and press the specimen. Use the elasticity of the spring to make the upper surface of the specimen flush with the small square frame. Rotate the limit plate on the small square frame to fix the position of the specimen. Then apply waterproof glue and smooth the joint formed by the top surface of the specimen and the inner frame of the small square frame to prevent the drainage on the surface of the specimen from directly flowing into the drainage channel from the joint. Close the control valves of the third and fourth water collecting tanks, and open the drainage channel and the control valve of the second water collecting tank.

[0018] (2) Measure the maximum drainage capacity P of the porous asphalt concrete specimen: adjust the height of each support leg to achieve the simulated longitudinal and transverse slope of the road surface required for the test, then turn on the power switch, adjust the water supply flow rate through the flow digital display controller to reach the initial rainfall intensity required for the test, recorded as Q1 (mL / s), record the rainfall time as T (s), turn on the water supply switch, start the test, and immediately close the control valve of the drainage channel and the second water collection tank after the rainfall ends. After the display values ​​of the first and second weighing instruments are stable, the drainage volume on the surface and inside of the specimen is recorded as V 表1 (mL), V 内1 (mL), then open the control valves of the drainage channel, the second water collecting tank, the third water collecting tank and the fourth water collecting tank to re-collect the water into the first water collecting tank. Under the condition that other working conditions remain unchanged, increase the water flow rate according to the preset proportion of the test and repeat the test. Record the different water flow rates Q i (mL / s), the surface water displacement V of the specimen 表i (mL) and the internal displacement V of the specimen 内i (mL).

[0019] (3) Using the recorded specimen surface and internal drainage data, a line graph is drawn with the water flow rate as the horizontal axis and the specimen drainage as the vertical axis. The horizontal axis corresponding to the inflection point in the line graph where the growth of the specimen internal drainage obviously slows down with the increase of the water flow rate is taken as the specimen maximum drainage capacity interval value P1; the horizontal axis corresponding to the inflection point in the line graph where the growth of the specimen surface drainage obviously speeds up with the increase of the water flow rate is taken as the maximum drainage capacity interval value P2; then the maximum drainage capacity P of the porous asphalt concrete specimen is calculated by the formula.

[0020] Preferably, the calculation formula for the maximum drainage capacity P of the porous asphalt concrete specimen in step (2) is: Unit: mL / s.

[0021] Beneficial effects: The present invention has the following advantages:

[0022] (1) The drainage of porous asphalt concrete specimens is divided into two parts: surface drainage and internal drainage. This can match the drainage path of actual porous asphalt pavement when it encounters rainfall, especially heavy rainfall. Based on this, the maximum drainage capacity range of the specimen is obtained through reasonable test steps and the analysis form of the line graph, and the maximum drainage capacity value of the specimen is calculated through the formula.

[0023] (2) This experimental device has a simple structure and flexible operation. It can accurately simulate different rainfall intensities and transverse and longitudinal slopes of the road surface, and realize water recycling and save resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a test device for measuring maximum drainage capacity in an embodiment of the present invention;

[0025] Figure 2 This is a front view of a test device for measuring maximum drainage performance in an embodiment of the present invention;

[0026] Figure 3 Schematic diagram of a specimen supporting mechanism in an embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the structure of the specimen supporting mechanism after the specimen is placed in the embodiment of the present invention;

[0028] Figure 5 A top view of the specimen supporting mechanism after the specimen is placed in the embodiment of the present invention;

[0029] Figure 6 is a schematic diagram of the specimen at position I;

[0030] Figure 7 It is a schematic diagram of the position II where the specimen is located;

[0031] Figure 8 This is the maximum drainage capacity analysis diagram.

[0032] In the figure: 1-working cabinet; 2-drain outlet; 3-water supply system; 31-water pump; 32-first water collecting tank; 33-water pipe; 34-water supply switch; 35-power switch; 36-flow digital display controller; 37-support frame; 38-nozzle; 4-specimen supporting mechanism; 41-specimen supporting frame; 411-square small frame; 412-spring; 413-bottom plate; 414-limiting plate; 42-oblique drainage plate; 43-square large frame; 44-drainage channel; 45-support leg; 5-collecting and weighing assembly; 51-second weighing scale; 52-fourth water collecting tank; 53-first weighing scale; 54-third water collecting tank; 55-second water collecting tank; 6-porous asphalt concrete specimen. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0034] This embodiment provides a test device for measuring the drainage performance of porous asphalt concrete. Figure 1-Figure 7 As shown: it includes a work cabinet 1, a water supply system 3, a collection and weighing component 5, and a test piece supporting mechanism 4; a drain port 2 is provided on the lower right side of the top plate of the work cabinet 1, and its internal space is divided into left and right areas, and the right area is divided into upper and lower layers by a partition, and the lower area can be used to place the test piece; the water supply system 3 includes a first water collecting tank 32 placed in the left area inside the work cabinet 1, a water pump 31 placed in the first water collecting tank 32, a support frame 37 installed on the work cabinet 1, a nozzle 38 arranged on the support frame 37, a power switch 35, a water supply switch 34, a flow digital display controller 36, and a water pump 33 connecting the water pump 31 and the nozzle 38; the water flow rate of the nozzle 38 can be accurately adjusted and displayed in real time by the flow digital display controller 36, so as to simulate different rainfall intensities.

[0035] The collecting and weighing assembly 5 comprises a second weighing scale 51 placed on the upper layer of the right area inside the work cabinet 1, a fourth water collecting tank 52 placed on the second weighing scale 51, a second water collecting tank 55 placed on the work cabinet 1, a waterproof first weighing scale 53 placed in the second water collecting tank 55 and a third water collecting tank 54 placed thereon; the fourth water collecting tank 52, the second water collecting tank 55 and the third water collecting tank 54 are all equipped with control valves, and the collected water can be re-integrated into the first water collecting tank 32 through the control valve to realize water recycling; the control valve of the second water collecting tank 55 is located in the drain outlet 2.

[0036] The specimen support mechanism 4 is placed in the second water collecting tank 55 and is located directly below the nozzle 37, and includes a specimen support frame 41, a large square frame 43 located directly below the specimen support frame 41, four oblique drainage plates 42 connecting the specimen support frame 41 and the large square frame 43 into a whole, a drainage channel 44 arranged at the bottom of the large square frame 43, and four supporting legs 45; the specimen support frame 41 includes a small square frame 411, a limit plate 414 movably arranged on the small square frame 411, and a bottom plate 413 having the same horizontal size as the small square frame 411 and located directly below it. And four corners are connected with springs of the bottom plate 413 and the small square frame 411; the position of the specimen can be fixed by rotating the limit plate 414; the bottom plate 413 directly supports the specimen; the oblique drainage plate 42 can guide the drainage on the surface of the specimen to flow into the second water collecting tank 55, and then flow into the fourth water collecting tank 52 through the control valve of the second water collecting tank; the drainage channel 44 can guide the drainage inside the specimen to flow into the third water collecting tank 54, and a control valve is provided at the bottom of the drainage channel; the height of the support leg 45 can be adjusted by a thread to simulate the longitudinal and transverse slopes of the actual road surface.

[0037] The specimen is a porous asphalt concrete specimen 6 formed by the rolling wheel method, with a size of 300mm×300mm×50~100mm. A waterproofing agent is applied to the bottom to simulate a waterproof bonding layer, so that the internal drainage of the specimen is discharged from the side of the specimen to simulate the actual drainage path of the drainage pavement; the effective rainfall area of ​​the nozzle 38 is less than 300mm×300mm to ensure that rainfall only acts on the specimen; the horizontal size of the inner frame of the square small frame 411 is 300mm×300mm to ensure its fit with the specimen.

[0038] When the porous asphalt concrete specimen 6 is just placed in the specimen support 41, its height is higher than the small square frame 411. At this time, the elasticity of the spring 412 can be used to press the specimen from above to make its height flush with the small square frame 411, and fix it by rotating the limit plate 414 on the small square frame 411.

[0039] The specific steps of the method for measuring the maximum drainage capacity of porous asphalt concrete in this embodiment are as follows:

[0040] Step 1: Prepare the specimen: Use the indoor roller method to form a porous asphalt concrete specimen with a size of 300mm×300mm×50mm. The void ratio is measured by the volume method to be 20%. Apply waterproofing agent on the bottom of the specimen to simulate the waterproof adhesive layer under the actual road drainage surface layer. Curing at room temperature for 20 hours is ready for use.

[0041] Step 2: Preparation before the experiment: Place the porous asphalt concrete specimen in the specimen support frame. Figure 6The test piece is then pressed to position I as shown, and the elasticity of the spring is used to make it Figure 7 At position II as shown, then rotate the limit plate on the small square frame inward to fix the position of the specimen. After ensuring that the height of the specimen is flush with the small square frame, apply waterproof glue and smooth the joint formed by the specimen and the inner frame of the small square frame to prevent drainage on the surface of the specimen from flowing directly into the drainage channel from the joint. Then close the corresponding control valves of the third water collecting tank and the fourth water collecting tank, and open the drainage channel and the corresponding control valve of the second water collecting tank.

[0042] Step 3: Measure the surface and internal drainage of the specimen under different rainfall intensities: Determine the horizontal and vertical directions according to the wheel rolling direction when the specimen is formed, adjust the height of each support leg through the thread, make the horizontal slope of the road surface 2%, the vertical slope 3%, and the combined slope 3.6%, then turn on the power switch, adjust the water supply flow rate through the flow digital display controller to reach the initial rainfall intensity of the test Q1 = 60mL / s, fix the rainfall time to 40s, turn on the water supply switch, start the test, and after the rainfall is over, immediately close the drainage channel and the control valve of the second water collection tank, and turn off the water supply switch at the same time. After the display values ​​of the first and second weighing instruments are stable, the surface and internal drainage of the specimen is obtained as V 表1 (mL), V 内1 (mL), then open the control valves of the drainage channel, the second water collection tank, the third water collection tank and the fourth water collection tank to re-collect the water into the first water collection tank. When the road slope and rainfall time remain unchanged, the water supply flow rate is increased by 5mL / s each time and repeated tests are carried out. The water discharge volume on the surface and inside of the specimen under different water supply flow rates is V 表i (mL), V 内i (mL).

[0043] Step 4: Draw a line graph of the data: Draw a line graph of the surface and internal displacement data of the specimen at different water flow rates, with the horizontal axis being the water flow rate and the vertical axis being the displacement of the specimen, such as Figure 8 As shown, the horizontal coordinate corresponding to the inflection point in the line graph where the internal drainage of the specimen increases significantly slower with the increase of the water supply flow rate is taken as the maximum drainage capacity interval value P1 (mL / s) of the specimen; the horizontal coordinate corresponding to the inflection point in the line graph where the surface drainage of the specimen increases significantly faster with the increase of the water supply flow rate is taken as the maximum drainage capacity interval value P2 (mL / s).

[0044] (5) Through the formula Calculate the maximum drainage capacity P of the specimen: The maximum drainage capacity interval of the porous asphalt concrete specimen with a porosity of 20% is [75, 80], and the maximum drainage capacity value P = 77.5 (mL / s);

[0045] The test device provided in this embodiment can use porous asphalt concrete specimens formed indoors for testing, and can simulate different rainfall intensities and transverse and longitudinal slopes of the road surface, respectively collect drainage on the surface and inside of the specimen, and use the relationship line graph of the collected surface and internal drainage of the specimen and the water supply flow rate to analyze and determine the maximum drainage capacity of the specimen, thereby providing a reasonable warning range for the road department for the use of drainage pavement during rainfall, especially heavy rainfall.

[0046] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A test device for measuring the maximum drainage capacity of porous asphalt concrete, characterized in that: It includes working cabinet, water supply system, collection and weighing components and specimen supporting mechanism; A first water collecting tank is provided inside the working cabinet, and a water pump of the water supply system is placed inside the first water collecting tank; The collecting and weighing assembly comprises a second water collecting tank placed above the working cabinet, a third water collecting tank placed inside the second water collecting tank, and a first weighing instrument located below the third water collecting tank; a second control valve port is provided at the bottom of the second water collecting tank; a fourth water collecting tank and a second weighing instrument located below the fourth water collecting tank are provided below the second control valve port; the fourth water collecting tank and the second weighing instrument are located inside the working cabinet; The specimen supporting mechanism is placed in the second water collecting tank and is located directly below the nozzle of the water supply system. The specimen supporting mechanism includes a specimen supporting frame, a large square frame located directly below the specimen supporting frame, a drainage channel and supporting legs arranged at the bottom of the large square frame, and the water outlet of the drainage channel is located above the third water collecting tank and is provided with a first control valve port; The specimen support frame comprises a small square frame and a bottom plate located below the small square frame, the small square frame and the bottom plate are connected via a spring, and a limiting plate is movably connected to the small square frame; The square small frame and the square large frame are connected by oblique guide plates on all sides, and the outer edge of the bottom of the oblique guide plates is located in the second water collecting tank.

2. A test device for measuring the maximum drainage capacity of porous asphalt concrete according to claim 1, characterized in that: A test piece placement area is provided below the second weighing instrument.

3. A test device for measuring the maximum drainage capacity of porous asphalt concrete according to claim 1, characterized in that: A third control valve port is provided at the bottom of the third water collecting tank, a fourth control valve port is provided at the bottom of the fourth water collecting tank, and a water outlet of the fourth control valve port is located above the first water collecting tank.

4. A test device for measuring the maximum drainage capacity of porous asphalt concrete according to claim 1, characterized in that: The water supply system includes a water pump, a water pipe and a nozzle. The water pipe and the nozzle are fixed by a support frame. The support frame is provided with a power switch, a water supply switch and a flow digital display controller. The flow digital display controller is connected to the water pump.

5. A test device for measuring the maximum drainage capacity of porous asphalt concrete according to claim 1, characterized in that: The effective rainfall area of ​​the nozzle is less than 300mm×300mm, and the horizontal size of the inner frame of the square small frame is 300mm×300mm.

6. A method for measuring the maximum drainage capacity of porous asphalt concrete, using the test device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) Place the specimen in the specimen support and press the specimen. Use the elasticity of the spring to make the upper surface of the specimen flush with the small square frame. Rotate the limiter on the small square frame to fix the position of the specimen. Then apply waterproof glue to the joint formed between the top surface of the specimen and the inner frame of the small square frame and smooth it to prevent the drainage on the surface of the specimen from directly flowing into the drainage channel from the joint. Close the control valves of the third and fourth water collecting tanks, and open the control valves of the drainage channel and the second water collecting tank. (2) Measure the maximum drainage capacity P of the porous asphalt concrete specimen: adjust the height of each support leg to achieve the simulated longitudinal and transverse slopes of the road surface required for the test, turn on the power switch, and adjust the water supply flow rate through the flow digital display controller to reach the initial rainfall intensity required for the test, recorded as Q1, mL / s, and the rainfall time is recorded as T, unit s. Turn on the water supply switch and start the test. After the rainfall ends, immediately close the control valves of the drainage channel and the second water collection tank. After the displayed values ​​of the first and second weighing instruments are stable, the drainage volume on the surface and inside of the specimen is recorded as V 表1 ,mL、V 内1 , mL, then open the control valves of the drainage channel, the second water collecting tank, the third water collecting tank and the fourth water collecting tank to re-collect the water into the first water collecting tank. Under the condition that other working conditions remain unchanged, increase the water flow rate according to the preset proportion of the test and repeat the test. Record the different water flow rates Q i In this case, the surface water displacement V of the specimen 表i and the internal displacement V of the specimen 内i ; (3) Using the recorded specimen surface and internal drainage data, a line graph is drawn with the water flow rate as the horizontal axis and the specimen drainage as the vertical axis. The horizontal axis corresponding to the inflection point in the line graph where the growth of the specimen internal drainage obviously slows down with the increase of the water flow rate is taken as the specimen maximum drainage capacity interval value P1; the horizontal axis corresponding to the inflection point in the line graph where the growth of the specimen surface drainage obviously speeds up with the increase of the water flow rate is taken as the maximum drainage capacity interval value P2; then the maximum drainage capacity P of the porous asphalt concrete specimen is calculated by the formula.

7. A method for measuring the maximum drainage capacity of porous asphalt concrete according to claim 6, characterized in that: The calculation formula for the maximum drainage capacity P of the porous asphalt concrete specimen in step (3) is: Unit: mL / s.

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