A test method for simulating clogging behavior of permeable pavement and analyzing clogging degree simultaneously

Abstract

This invention relates to the field of permeable pavement blockage analysis, and specifically to an experimental method for simulating the blockage behavior of permeable pavements and simultaneously analyzing the degree of blockage. The method includes: configuring permeable pavement materials and graded simulated blockage materials; calculating the gradation and mass of the simulated blockage materials spread on the permeable pavement material under different traffic loads to approximate the actual blockage situation of the permeable pavement as closely as possible; cleverly employing a constant head permeability coefficient testing device to introduce the blockage material into the permeable pavement test specimen using a constant pressure head, with a specified holding time of 2-3 minutes to ensure the stability of the permeable pavement blockage; and extracting pore characteristic parameters from the specimen surface using photographs and ImageJ software. By comparing the changes in pore characteristic parameters before and after blockage, the degree of blockage is determined. Compared with existing technologies, this invention has advantages such as enabling indoor simulation of the blockage behavior and degree of permeable pavements under different traffic carrying capacities.

Description

Technical Field

[0001] This invention relates to the field of permeable pavement blockage analysis, and in particular to a test method for simulating the blockage behavior of permeable pavements and analyzing the degree of blockage. Background Technology

[0002] With the large-scale promotion and application of permeable pavement in my country, the problem of clogging under long-term use conditions has emerged. During a large amount of traffic activities and vehicle-road interaction, a large amount of sediment will accumulate on the road surface. As the permeable pavement is used for a long time, the pores will become clogged, resulting in a decrease in water permeability and loss of a series of functions such as cooling and noise reduction, and it is also detrimental to the lifespan of the permeable pavement.

[0003] Indoor simulations of permeable pavement blockage can effectively help maintenance departments predict the actual blockage situation. However, it is important to note that the simulated blockage material should closely resemble the actual pavement surface deposits. This requires a well-designed gradation of the simulated blockage material and a scientifically controlled application rate to effectively simulate the actual blockage conditions of permeable pavements under different traffic loads or seasons. Furthermore, analyzing the degree of blockage during the simulation can provide valuable insights for determining the appropriate timing of maintenance.

[0004] Chinese patent application CN110487700A provides a method for testing the clogging performance of permeable concrete, but its method only macroscopically evaluates the clogging performance of permeable concrete and does not simulate the clogging situation of permeable pavement under different traffic loads, nor does it propose a simulation scheme that better meets practical applications. Chinese patent application CN116718529A provides an indoor testing method and device for the clogging performance of composite permeable pavement. The method includes: collecting clogging material on a test section, calculating a second mass of the clogging material on the test area based on a first mass of the clogging material on the test section, and determining the test area's clogging performance. The method involves determining the gradation of the blockage material corresponding to the blockage area, and preparing test sand and gravel based on the gradation and the second mass of the blockage material. Following a pre-defined test procedure, a permeability test is conducted on a prefabricated composite permeable panel using the prepared test sand and gravel. The permeability coefficient of the prefabricated composite permeable panel is calculated based on the permeability time. While this application provides a method for simulating and evaluating the blockage performance of permeable pavements indoors, it does not simulate and analyze specific road conditions. Currently, the actual application of permeable pavements involves various scenarios, necessitating the development of simulation and analysis methods that better suit practical applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a test method for simulating the clogging behavior of permeable pavements and analyzing the degree of clogging. This addresses the lack of consideration for the gradation type of road surface sediments in the existing permeable pavement clogging simulation, and realizes a simulated clogging test scheme for permeable pavements under different traffic loads. Through simple pore extraction and analysis methods, the degree of clogging of permeable pavements can be evaluated efficiently and accurately. At the same time, a constant head permeability coefficient testing device is cleverly used for experimental testing.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A test method for simulating the clogging behavior of permeable pavements includes:

[0008] Prepare permeable pavement material and simulated blocking material. Calculate and weigh the mass of the simulated blocking material spread on the permeable pavement material. Apply the simulated blocking material to the surface of the permeable pavement material and then place it in a permeability coefficient testing device for experimentation. Introduce water into the specimen and simultaneously introduce the simulated blocking material into the permeable pavement material. Analyze the porosity of the permeable pavement material surface.

[0009] Furthermore, the mass of the simulated plugging material applied to the surface of the permeable pavement material is calculated according to formula (Ⅰ):

[0010]

[0011] Where m is the mass of the simulated plugging material, d is the diameter of the permeable pavement material, and m i This simulates the cumulative amount of blockage per unit area.

[0012] Furthermore, the diameter of the permeable pavement material ranges from 101.6 ± 0.2 mm.

[0013] Furthermore, the simulated congestion material includes two gradations: a fully graded sand of uniform particle size distribution used to simulate heavy traffic, and a fully graded sand of predominantly coarse particles used to simulate light traffic.

[0014] The partial sieve residues of the fully graded sand (type 1) passing through the following sieve openings are as follows:

[0015] 4.75mm / 2.36mm / 1.18mm / 0.6mm / 0.3mm / 0.15mm / 0.075mm / <0.075mm: 0 / 3-3.5% / 12.5-13% / 15-15.5% / 24-24.5% / 17.5-18% / 18-18.5% / 7.5-8.5%;

[0016] The partial sieve residues of fully graded sand No. 2 passing through the following sieve openings are as follows:

[0017] 4.75mm / 2.36mm / 1.18mm / 0.6mm / 0.3mm / 0.15mm / 0.075mm / <0.075mm: 0 / 18-18.5% / 18-18.5% / 15-16% / 14-14.5% / 14-14.5% / 6-6.5% / 13-14%.

[0018] Furthermore, the permeable pavement material includes asphalt, coarse and fine aggregates, and mineral powder.

[0019] Furthermore, the asphalt is selected as high-viscosity modified asphalt, and the coarse and fine aggregates are selected as basalt.

[0020] Furthermore, the asphalt-aggregate ratio of the permeable pavement material is 3-5%.

[0021] Furthermore, the specimen was placed in a permeability testing device for testing. Under a constant water head (4cm), clear water was allowed to permeate the specimen for 2-3 minutes, which was recorded as one blockage.

[0022] Furthermore, the method involves repeating multiple clogging cycles to simulate the frequent clogging of permeable asphalt pavements under long-term use conditions.

[0023] Furthermore, after multiple clogging cycles, the specimens were dried in an 85°C oven for 8-10 hours, and then the surface of the specimens was photographed with a digital camera for subsequent analysis of the surface porosity.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] The method provided by this invention takes into account and optimizes the simulated blockages of different gradations to closely approximate actual road congestion conditions. It simulates the blockage behavior of permeable pavements under different traffic carrying capacities indoors. Through simple and convenient photography and pore feature extraction methods, it quantifies and analyzes the degree of blockage based on changes in surface pore feature parameters, providing a reference for maintenance decisions.

[0026] (1) Based on the actual road surface sediment collection and analysis results, this invention selects two types of simulated blockages with different gradations and sets a formula for calculating the spraying quality according to the blockage acceptance area of ​​the permeable pavement material, so as to approximate the actual blockage situation of the permeable pavement to the greatest extent.

[0027] (2) This invention specifies a test method for permeable pavement blockage, which cleverly uses a constant water head permeability coefficient test device to bring the blockage into the permeable pavement test specimen using a constant pressure water head, and specifies a holding time of 2-3 minutes to ensure the stability of permeable pavement blockage.

[0028] (3) This invention proposes a method for judging the degree of blockage based on the analysis of surface pore characteristics. After the blockage test, the surface of the specimen is digitally photographed, and the surface pore characteristic parameters of the specimen are extracted by combining Image J software. By comparing the changes in surface pore characteristic parameters before and after blockage, the degree of blockage is determined. Attached Figure Description

[0029] Figure 1 A flowchart of an experimental method for simulating the clogging behavior of permeable pavements and simultaneously analyzing the degree of clogging;

[0030] Figure 2 This is a surface pore feature extraction map based on digital photography and ImageJ.

[0031] Figure 3 This is a comparison chart of the surface porosity changes of the permeable pavement material in Example 1;

[0032] Figure 4 This is a comparison chart showing the changes in the number of pores on the surface of the permeable pavement material in Example 1;

[0033] Figure 5 This is a comparison chart of the fractal dimension changes on the surface of the permeable pavement material in Example 1;

[0034] Figure 6 This is a comparison chart of the surface porosity changes of the permeable pavement material in Example 2;

[0035] Figure 7 This is a comparison chart showing the changes in the number of pores on the surface of the permeable pavement material in Example 2;

[0036] Figure 8 This is a comparison chart of the fractal dimension changes on the surface of the permeable pavement material in Example 2. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] A test method for simulating the clogging behavior of permeable pavements and analyzing the degree of clogging, which can simulate the clogging behavior of permeable pavements under different traffic carrying capacities indoors, analyze the degree of clogging based on changes in surface porosity characteristics, and thus determine the clogging behavior of permeable pavements in actual applications, including:

[0039] Configuration of permeable pavement materials and simulated blockage materials:

[0040] Among them, the simulated blockage material is achieved through two types of simulated blockage materials with different gradations. Fully graded sand one is used to simulate road surface sediments with uniform particle size distribution under heavy traffic, and fully graded sand two is used to simulate road surface sediments with coarse particles under light traffic.

[0041] The corresponding gradations are shown in the table below:

[0042] Table 1

[0043]

[0044] The main materials for preparing permeable asphalt pavement materials include asphalt, coarse and fine aggregates, and mineral powder. The asphalt is high-viscosity modified asphalt, and the coarse and fine aggregates are all made of basalt. The asphalt-aggregate ratio (mass ratio of asphalt to all aggregates) is 5.0%. The gradation design of permeable asphalt pavement materials refers to the "Technical Specification for Design and Construction of Drainage Asphalt Pavement" (JTG / T3350-03—2020).

[0045] Calculate according to the following formula (Ⅰ): Calculate and weigh the mass of the simulated blocking material spread on the permeable pavement material. Apply the simulated blocking material to the surface of the permeable pavement material and then place it in the permeability coefficient testing device (the device is disclosed in the "Technical Specification for Permeable Cement Concrete Pavement" CJJ / T135-2009, the same below) for the experiment. Place the permeable asphalt pavement material with the simulated blocking material at the bottom of the sleeve, and then inject clean water at the top of the sleeve. Use the clean water to carry the blocking material into the interior of the permeable asphalt pavement material. Excess water will flow out from the overflow trough, allowing the clean water to penetrate the permeable asphalt pavement material. At the same time, the simulated blocking material will be carried into the permeable pavement material. Then, analyze the porosity of the surface of the permeable pavement material.

[0046]

[0047] Where m is the mass of the simulated plugging material, d is the diameter of the permeable pavement material, and m i This simulates the cumulative amount of blockage per unit area.

[0048] In some specific embodiments, the diameter of the permeable pavement material is in the range of 101.6 ± 0.2 mm, and 101.6 mm is taken as specified.

[0049] In some specific embodiments, m i The cumulative amount of simulated blockage per unit area is taken as 2000g / m². 2 .

[0050] In some specific embodiments, after weighing, the sand and gravel of different sizes are evenly mixed and placed in a clean tray, then dried at 105°C for 4 hours for later use.

[0051] In some specific embodiments, a constant head permeability coefficient testing device is used to simulate a clogging cycle. First, a clean, soft brush is used to evenly apply dried simulated clogging material to the surface of the permeable pavement material. Then, the material is placed in the constant head permeability coefficient testing device. To prevent side leakage, the top of the permeable pavement material is sealed with putty. After the permeable asphalt pavement material is placed in the cylinder of the device, gaps will appear around its perimeter. To prevent water from flowing out of these gaps, putty is used to seal them. Under a constant head, clean water is allowed to permeate the specimen, simultaneously introducing the surface clogging material into the permeable pavement specimen. This process is maintained for 2-3 minutes to ensure the clogging material fully enters the pavement's porous structure. This is recorded as one clogging cycle. Multiple clogging cycles can be performed as needed, following the same steps. After the clogging cycle, the specimen is placed in an 85℃ oven to dry for 8 hours. A digital camera is used to photograph the surface of the specimen for subsequent analysis of surface porosity. Method for analyzing the degree of clogging in permeable pavement:

[0052] After the circulation was blocked, the specimen was dried in an 85℃ oven for 8 hours. Then, the surface of the specimen was photographed using a digital camera, ensuring sufficient lighting and clear images. ImageJ software was then used to extract the surface porosity characteristics of the specimen. The main surface porosity characteristics are as follows:

[0053] Surface porosity P: The ratio of the total area of ​​pores in a two-dimensional plane to the cross-sectional area;

[0054] Surface porosity Pc: The number of two-dimensional planar pores in porous asphalt mixtures;

[0055] Surface equivalent aperture D: represents the diameter of the corresponding sphere that corresponds to the volume of the irregularly shaped pore;

[0056]

[0057] Where D is the equivalent diameter of the pores, ∑A i ∑P represents the total pore area of ​​the processed image. i This represents the total number of pores for each image.

[0058] The following embodiments are implemented based on the above-described technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0059] The following are more detailed implementation examples, which further illustrate the technical solution of the present invention and the technical effects that can be obtained.

[0060] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0061] Example 1

[0062] This embodiment provides a test method for simulating the clogging behavior of permeable pavements. This embodiment only performs one clogging cycle, and specifically includes the following steps:

[0063] (1) Preparation of permeable asphalt pavement material, the main materials include: asphalt, coarse and fine aggregates, and filler mineral powder. Among them, the asphalt is high-viscosity modified asphalt, and both coarse and fine aggregates are basalt. The asphalt-aggregate ratio (mass ratio of asphalt to all aggregates) is 5.0%. The gradation design of permeable asphalt pavement material refers to the "Technical Specification for Design and Construction of Drainage Asphalt Pavement" (JTG / T 3350-03—2020);

[0064] (2) After the material is prepared, a digital camera is used to take pictures of the surface of the permeable asphalt pavement material for subsequent analysis of the surface pore characteristics before clogging.

[0065] (3) Refer to the table below to prepare two types of simulated blockage materials, mix them evenly, place them in a clean tray, and dry them at 105℃ for 4 hours for later use.

[0066] Table 1

[0067]

[0068] (4) Calculate the mass of the simulated blockage material spread on the surface of the permeable asphalt pavement material according to the following formula (Ⅰ) and the surface area of ​​the permeable asphalt pavement material, and then weigh it.

[0069] In this embodiment, the diameter of the permeable asphalt pavement material is 101.6 mm; the thickness of the permeable asphalt pavement material is 63.5 mm.

[0070] The cumulative amount of simulated blockage per unit area is taken as 2000 g / m². 2 ;

[0071] According to formula (Ⅰ), the mass of the simulated blocking material spread on the surface of the permeable asphalt pavement is 16.21g;

[0072]

[0073] Where m is the mass of the simulated plugging material, d is the diameter of the permeable pavement material, and m i This simulates the cumulative amount of blockage per unit area.

[0074] (5) Use a clean soft brush to evenly apply the two gradations of simulated plugging materials to the surface of the permeable asphalt pavement material, place it in the constant water head permeability coefficient test device, and seal the upper part of the permeable asphalt pavement material with putty to prevent side leakage.

[0075] (6) While allowing clean water to permeate the specimen under a constant water head (4cm), the blockage material is introduced and maintained for 2-3 minutes, which is recorded as one blockage cycle;

[0076] (7) After the first clogging cycle, the specimen was dried in an 85℃ oven for 8 hours. The surface of the specimen was photographed using a digital camera for subsequent analysis of the surface porosity characteristics after clogging. ImageJ software was used to extract the surface porosity characteristic parameters of the specimen (e.g., ...). Figure 1 The image shown is a surface pore feature extraction map based on digital photography and ImageJ. The main surface pore feature parameters are as follows:

[0077] Surface porosity P: The ratio of the total area of ​​pores in a two-dimensional plane to the cross-sectional area;

[0078] Surface porosity Pc: The number of two-dimensional planar pores in porous asphalt mixtures;

[0079] Surface equivalent aperture D: represents the diameter of the corresponding sphere that corresponds to the volume of the irregularly shaped pore;

[0080]

[0081] Where D is the equivalent diameter of the pores, ∑A i ∑P represents the total pore area of ​​the processed image. i This represents the total number of pores for each image.

[0082] (8) Draw the changes in surface porosity characteristics of permeable asphalt pavement material before and after the first clogging, as shown in the figure. Figure 2 , 3 As shown in Figure 4, where, Figure 2 This is a comparison chart of the surface porosity changes of the permeable pavement material in this embodiment; Figure 3 This is a comparison chart showing the changes in the number of pores on the surface of the permeable pavement material in this embodiment; Figure 4 This is a comparison chart of the fractal dimension changes of the permeable pavement material surface in this embodiment;

[0083] The data shows that after the initial blockage, the surface porosity decreased slightly, but the number of surface pores increased significantly. This indicates that the pore area of ​​the two-dimensional cross-section decreased, but the surface formed finer pores due to the introduction of the blockage, increasing the number of pores. The fractal dimension did not change much. The fractal dimension is often used to quantitatively describe the texture features of an image. The various indicators are directly displayed by ImageJ software.

[0084] Example 2

[0085] This embodiment provides a test method for simulating the clogging behavior of permeable pavements. This embodiment performs multiple clogging cycles, and differs from Embodiment 1 in that:

[0086] In step (6), after one blocking cycle, the blocking step is repeated. When the water level in the constant head permeability coefficient test device no longer drops within a fixed time, the specimen is considered to be completely blocked and recorded as the last blocking cycle. The other steps are the same as in Example 1.

[0087] The changes in surface porosity characteristics of permeable asphalt pavement materials before and after the first clogging are plotted as follows: Figure 5 , 6 As shown in Figures 7 and 8, among which, Figure 5 This is a comparison chart of the surface porosity changes of the permeable pavement material in this embodiment; Figure 6 This is a comparison chart showing the changes in the number of pores on the surface of the permeable pavement material in this embodiment; Figure 7 This is a comparison chart of the fractal dimension changes on the surface of the permeable pavement material in this embodiment.

[0088] It can be seen that after complete blockage, the surface porosity decreased to 10% or less. The fully graded sand 1, being more uniform, had more particles penetrating into the specimen, resulting in a greater decrease. In contrast, the fully graded sand 2, with its higher proportion of coarse particles, had more surface porosity, leading to a significant increase in the number of surface pores. The fractal dimension of both sands decreased significantly after complete blockage.

[0089] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A test method for simulating the clogging behavior of permeable pavements, characterized in that, include: Prepare permeable pavement material and simulated blocking material, calculate and weigh the mass of simulated blocking material spread on the permeable pavement material, apply the simulated blocking material to the surface of the permeable pavement material, and then place it in a permeability coefficient testing device for experimentation. Allow water to permeate the specimen, and at the same time bring the simulated blocking material into the permeable pavement material. Then analyze the porosity of the surface of the permeable pavement material. The mass of the simulated plugging material applied to the surface of the permeable pavement material is calculated according to formula (Ⅰ): （Ⅰ） Where m is the mass of the simulated plugging material, d is the diameter of the permeable pavement material, and m i This simulates the cumulative amount of blockage per unit area. The simulated congestion material includes two gradations: a fully graded sand of uniform particle size distribution used to simulate heavy traffic, and a fully graded sand of predominantly coarse particles used to simulate light traffic. The partial sieve residues of the fully graded sand (type 1) passing through the following sieve openings are as follows: 4.75mm / 2.36mm / 1.18mm / 0.6mm / 0.3mm / 0.15mm / 0.075mm / <0.075mm: 0 / 3-3.5% / 12.5-13% / 15-15.5% / 24-24.5% / 17.5-18% / 18-18.5% / 7.5-8.5%; The partial sieve residues of fully graded sand No. 2 passing through the following sieve openings are as follows: 4.75mm / 2.36mm / 1.18mm / 0.6mm / 0.3mm / 0.15mm / 0.075mm / <0.075mm: 0 / 18-18.5% / 18-18.5% / 15-16% / 14-14.5% / 14-14.5% / 6-6.5% / 13-14%; The specimen was placed in a permeability testing device for testing. Under a constant water head, clear water was allowed to permeate the specimen for 2-3 minutes, which was recorded as one blockage. The blockage was repeated multiple times. After multiple blockage cycles, the specimen was placed in an 85℃ oven to dry for 8-10 hours. The surface of the specimen was then photographed with a digital camera for subsequent analysis of the surface porosity.

2. The test method for simulating the clogging behavior of permeable pavement according to claim 1, characterized in that, The diameter of the permeable pavement material is in the range of 101.6 ± 0.2 mm.

3. The test method for simulating the clogging behavior of permeable pavement according to claim 1, characterized in that, The permeable pavement material includes asphalt, coarse and fine aggregates, and mineral powder.

4. The test method for simulating the clogging behavior of permeable pavement according to claim 3, characterized in that, The asphalt is selected from high-viscosity modified asphalt, and the coarse and fine aggregates are selected from basalt.

5. The test method for simulating the clogging behavior of permeable pavement according to claim 1, characterized in that, The asphalt-aggregate ratio of the permeable pavement material is 3-5%.

6. The test method for simulating the clogging behavior of permeable pavement according to claim 1, characterized in that, Place the specimen in a permeability testing device for testing. Allow clean water to permeate the specimen for 2-3 minutes under a constant water head, and record this as one blockage.

7. The test method for simulating the clogging behavior of permeable pavements according to claim 6, characterized in that, This method involves repeated blocking multiple times during the process.

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