Asphalt concrete pavement snow-melting and ice-melting discrete element numerical simulation method

Abstract

This invention discloses a discrete element numerical simulation method for snow and ice melting on asphalt concrete pavements. First, a two-dimensional discrete element sample model of the asphalt concrete pavement and ice surface is established, and different micromechanical parameters are assigned to different bonding types. After heat is transferred to the ice layer, the mass loss of ice particles, the amount of liquid generated, and the new size of the ice particles are calculated at regular intervals. The ice melting rate is transferred to the CFD field, and then the CFD, using coupled information and with the help of the developed OpenFoam multiphase solver, calculates the temperature field within the ice layer. This method can effectively simulate the effect of carbon fiber heating on snow and ice melting of asphalt concrete pavements, and can be used to study the heating efficiency of carbon fibers and the ice melting process of the pavement.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering construction technology, and relates to a pavement snow melting and ice removal technology, and more particularly to a discrete element numerical simulation method for snow melting and ice removal of asphalt concrete pavement. Background Technology

[0002] Road surface conditions are a crucial factor affecting road traffic. In winter, snow accumulation or icing on roads has a significant impact on transportation, causing considerable disruption to the national economy and people's lives, and posing significant traffic hazards. The currently widely used method of salting to melt snow and ice severely affects the durability of concrete and damages road infrastructure. Therefore, the pursuit of new snow and ice melting methods is of great practical significance. Carbon fiber conductive heating has become an effective method for snow and ice melting. With the rapid development of computer technology and the significant improvement in human computing power, numerical simulation has gradually become an important means for understanding natural laws. However, the finite element method or finite difference method currently widely used cannot accurately reflect the melting process of refined ice particle elements and the interaction between the liquid temperature field and ice particles after the ice layer melts. Compared with the finite element method and finite difference method, the numerical simulation method coupled with CFD-DEM has natural advantages in simulating discrete elements and particle-fluid interactions. However, its application in the field of snow and ice melting using carbon fiber conductive heating for pavement has not yet been reported. Summary of the Invention

[0003] The purpose of this invention is to provide a discrete element numerical simulation method for snow and ice melting on asphalt concrete pavements. This method simplifies the asphalt concrete pavement under low-temperature conditions into concrete particles, asphalt particles, ice particles, concrete-concrete bonds, concrete-asphalt bonds, asphalt-asphalt bonds, ice-ice bonds, and ice-asphalt bonds. The method uses particles to simulate carbon fiber heating the concrete subgrade and employs CFD-DEM coupling to simulate the ice melting process on the pavement. This approach is simple to operate, provides reliable results, and effectively simulates the snow and ice melting process on pavements.

[0004] The technical solution adopted to achieve the purpose of this invention is as follows:

[0005] A discrete element numerical simulation method for snow melting and ice removal on asphalt concrete pavement, characterized by the following steps:

[0006] Step 1: Establish a two-dimensional discrete element sample model of asphalt concrete pavement and ice surface and assign mechanical parameters. The two-dimensional discrete element sample model includes a geometric model and a contact model. The geometric model includes a concrete particle layer, an asphalt particle layer and an ice particle layer arranged from bottom to top. The contact model includes the bonding between adjacent particles. Carbon fiber particles are set in the concrete particle layer to simulate carbon fiber heating. The ice melting process is simulated by changing the mass of ice particles in the ice particle layer.

[0007] Step 2: Set the heat transfer model for each particle in the two-dimensional discrete element sample model, and then set the heating temperature for the carbon fiber particles to simulate the melting process.

[0008] Step 3: During the temperature transfer process, the surface temperature of the ice particles is automatically calculated at regular intervals, thereby calculating the mass loss of the ice particles, the new particle size, and the amount of liquid generated.

[0009] Step 4: Transmit data such as the ice melting rate and the amount of liquid generated after the ice particles melt to the CFD unit. Then, the CFD unit will use the coupling information with the help of the developed OpenFoam multiphase solver to calculate the temperature field inside the ice layer and update the surface temperature of the ice particles.

[0010] Step 5: After the ice layer has completely melted, complete a numerical simulation of snow melting and ice removal.

[0011] This invention uses concrete particle layers composed of concrete particles to simulate roadbeds, asphalt particle layers composed of asphalt particles to simulate road surfaces, and ice particle layers composed of ice particles to simulate ice layers. The concrete-concrete bond refers to the bond between concrete particles, the asphalt-asphalt bond to the bond between asphalt particles, the ice-ice bond to the bond between ice particles, the asphalt-ice bond to the bond between asphalt particles and ice particles, and the concrete-asphalt bond to the bond between concrete particles and asphalt particles. By establishing contact models based on these bonding relationships and setting mechanical parameters for each particle, the invention aims to truly simulate the snow-melting and ice-de-icing process of asphalt concrete pavements.

[0012] Since actual asphalt concrete pavement is designed in layers, the structural changes of each part on the cross section are very small. Therefore, a two-dimensional model of the cross section can be used to simulate the three-dimensional real situation, which greatly reduces the amount of calculation. Since in the two-dimensional model, the heated carbon fiber is cut into granular points, carbon fiber granules are used to simulate the heating of carbon fiber.

[0013] Furthermore, the contact models include concrete-concrete bond, asphalt-asphalt bond, concrete-asphalt bond, asphalt-ice bond, and ice-ice bond.

[0014] Furthermore, in step 3, the method for calculating the mass loss of ice particles is as follows:

[0015]

[0016] In the above formula, m′ is the mass loss when the ice particles melt, ρ is the density of the ice particles, and L f h is the latent heat of the ice particles, and h is the surface temperature of the ice particles. m The melting temperature of the ice particles is 0℃, and Δt is the time variable after melting begins.

[0017] Furthermore, in step 1, a two-dimensional discrete element sample model of asphalt concrete pavement and ice surface is established using PFC2D particle flow calculation software.

[0018] In this invention, particles are used to simulate the carbon fiber heating process. The actual temperature at which carbon fiber conducts electricity during heating can be selected, and the heat transfer state between the roadbed, pavement, and ice layer can be adjusted by setting parameters to make it as realistic as possible. The initial ambient temperature is given as 0℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. This invention simulates the heating of concrete subgrade by carbon fiber through particle simulation and uses CFD-DEM coupling to simulate the melting process of ice on the road surface. During the simulation, discrete element samples of the asphalt concrete pavement and ice layer are first established, and different micromechanical parameters are assigned to different bonding types. The mass loss of ice particles and the amount of liquid generated at the current time point are calculated, and the new particle size is then calculated. The ice melting rate is transferred to the CFD field, and then the CFD uses the coupling information, with the help of the developed OpenFoam multiphase solver, to calculate the temperature field within the ice layer. This method uses discrete element software to simulate the subgrade, pavement, and ice layer, and uses CFD to calculate the flow field temperature. It is simple to operate and can effectively simulate the snow-melting and ice-reducing effect of carbon fiber heating on asphalt concrete pavement. It can be used to study the heating efficiency of carbon fiber and the ice-reducing process of the road surface, providing a theoretical basis for road snow-melting and ice-reducing design.

[0021] 2. This invention uses a two-dimensional model to simulate the snow melting and ice removal process of asphalt concrete pavement in a three-dimensional state, which greatly reduces the amount of calculation. Attached Figure Description

[0022] Figure 1 This is a flowchart of the discrete element simulation of asphalt concrete pavement.

[0023] Figure 2 This is a schematic diagram of a two-dimensional discrete element sample model for asphalt concrete pavement and ice surface.

[0024] 1-Concrete particle layer, 2-Asphalt particle layer, 3-Ice particle layer, 4-Carbon fiber particles. Detailed Implementation

[0025] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0026] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the protection scope of the present invention.

[0027] This invention ignores the volume changes of the roadbed and pavement due to temperature; the heating temperature of the carbon fiber particles does not change; the particles are used to simulate carbon fiber heating, and the ice melting process is simulated by changing the mass of the ice particles, and the melting rate is transferred to the CFD element to calculate the temperature field.

[0028] Example 1: As Figure 1 and Figure 2 As shown, a discrete element numerical simulation method for snow melting and ice removal on asphalt concrete pavement includes the following steps:

[0029] Step 1: Using PFC2D particle flow calculation software, establish a two-dimensional discrete element sample model for asphalt concrete pavement and ice layer. The two-dimensional discrete element sample model is a particle flow sample, such as... Figure 2 As shown, the two-dimensional discrete element sample model includes a geometric model and a contact model. The geometric model includes a concrete particle layer 1, an asphalt particle layer 2, and an ice particle layer 3 arranged sequentially from bottom to top. The contact model includes the bonding between adjacent particles. Carbon fiber particles 4 are placed in the concrete particle layer 1 to simulate carbon fiber heating. The melting process of the ice layer is simulated by changing the mass of the ice particles in the ice particle layer. The contact model includes concrete-concrete bonding, asphalt-asphalt bonding, concrete-asphalt bonding, asphalt-ice bonding, and ice-ice bonding.

[0030] Step 2: Assign mechanical parameters to each particle of the two-dimensional discrete element sample model and set the heat transfer model; after setting the initial heating temperature for the carbon fiber particles, start simulating the ice melting process.

[0031] Step 3: During the melting process, the PFC2D particle flow calculation software automatically calculates the surface temperature of the ice particles at the current time.

[0032] The mass loss of ice particles at the current temperature is calculated based on their surface temperature. The method for calculating mass loss is as follows:

[0033]

[0034] In the above formula, m′ is the mass loss when the ice particles melt, ρ is the density of the ice particles, and L fh is the latent heat of the ice particles, and h is the surface temperature of the ice particles. m Δt represents the melting temperature of the ice particles, which is 0℃ here, and Δt is the time variable after melting begins.

[0035] The new particle size and the amount of liquid produced are calculated by the mass loss of the ice particles.

[0036] Step 4: Transfer the amount of liquid generated after the ice layer begins to melt to the CFD unit, calculate the current temperature field, feed it back to the ice particles, and calculate the new particle surface temperature.

[0037] Step 5: Repeat this melting process until the last ice particle has completely melted, thus completing one snow melting and ice-melting numerical simulation.

[0038] The above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Although the invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the invention do not depart from the spirit and scope of the invention and should be covered within the scope of the claims of the invention.

Claims

1. A discrete element numerical simulation method for snow melting and ice removal on asphalt concrete pavements, characterized in that, Includes the following steps: Step 1: Establish a two-dimensional discrete element sample model of asphalt concrete pavement and ice surface and assign mechanical parameters. The two-dimensional discrete element sample model includes a geometric model and a contact model. The geometric model includes a concrete particle layer, an asphalt particle layer and an ice particle layer arranged from bottom to top. The contact model includes the bonding between adjacent particles. Carbon fiber particles are set in the concrete particle layer to simulate carbon fiber heating. The ice melting process is simulated by changing the mass of ice particles in the ice particle layer. Step 2: Set the heat transfer model for each particle in the two-dimensional discrete element sample model, and then set the heating temperature for the carbon fiber particles to simulate the melting process. Step 3: During the temperature transfer process, the surface temperature of the ice particles is automatically calculated at regular intervals, thereby calculating the mass loss of the ice particles, the new particle size, and the amount of liquid generated. Step 4: Transmit data such as the ice melting rate and the amount of liquid generated after the ice particles melt to the CFD unit. Then, the CFD unit will use the coupling information with the help of the developed OpenFoam multiphase solver to calculate the temperature field inside the ice layer and update the surface temperature of the ice particles. Step 5: After the ice layer has completely melted, complete a numerical simulation of snow melting and ice removal. In step 3, the method for calculating the mass loss of ice particles is as follows: In the above formula, This refers to the mass loss when ice particles melt. The density of ice particles, The latent heat of ice particles, The surface temperature of the ice particles. This is the melting temperature of ice particles, which is 0℃ here. This is the time variable after melting begins.

2. The discrete element numerical simulation method for snow melting and ice removal on asphalt concrete pavement according to claim 1, characterized in that: The contact models include concrete-concrete bond, asphalt-asphalt bond, concrete-asphalt bond, asphalt-ice bond, and ice-ice bond.

3. The discrete element numerical simulation method for snow melting and ice removal on asphalt concrete pavement according to claim 1, characterized in that: In step 1, a two-dimensional discrete element sample model of asphalt concrete pavement and ice surface is established using PFC2D particle flow calculation software.

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