Optimization method for key sieve pore passing rate of AC-13 mixture coarse aggregate

Abstract

The invention relates to the technical field of traffic civil engineering, and discloses an AC-13 mixture coarse aggregate key mesh passing rate optimization method, which comprises the following steps: determining standard particle size composition in aggregate, and generating a closed rectangular area by using PFC2D; calculating an area composed of standard particle sizes in the aggregate, creating and storing polygonal information, generating circular particles, converting the polygonal information of the aggregate into coarse aggregate units, and generating an aggregate mixture model; the aggregate standard quantity is determined, aggregate mixture models of different proportions are generated, and the sieve mesh passing rate is controlled; pressurizing the model to monitor the stress; in the model pressurization stress monitoring process, contact force is obtained, residual average contact force is calculated, pressurization and contact force calculation is carried out on different aggregate mixture models, and the optimal aggregate proportion is determined; and the coarse aggregate key sieve pore passing rate is optimized through the optimal aggregate proportion. The invention provides a special coarse aggregate key sieve pore passing rate optimization method for an AC-13 asphalt mixture.

Description

Technical Field

[0001] The present invention relates to the technical field of transportation civil engineering, and in particular to a method for optimizing the pass rate of key sieve holes of coarse aggregate of an AC-13 mixture. Background Art

[0002] AC-13 asphalt mixture is a commonly used pavement construction material, especially in the road surface layer. However, AC-13 asphalt mixture has serious early disease problems during use, such as rutting and fatigue cracking. The coarse aggregate skeleton gradation of AC-13 asphalt mixture is a key factor in ensuring its performance. By optimizing the coarse aggregate skeleton gradation, the mechanical properties, durability, construction performance and anti-skid properties of the mixture can be significantly improved, while reducing project costs and environmental impact. Therefore, rationally and accurately optimizing the critical sieve pass rate of the coarse aggregate of AC-13 asphalt mixture is of great significance to improving the durability of AC-13 asphalt mixture.

[0003] In actual projects, the coarse aggregate gradation of AC-13 asphalt mixture is mainly composed of three types of aggregate: 10-15mm aggregate (mainly used to adjust the pass rate of 13.2mm and 9.5mm sieve apertures), 5-10mm aggregate (mainly used to adjust the pass rate of 4.75mm sieve apertures), and 3-5mm aggregate (mainly used to adjust the pass rate of 2.36mm sieve apertures). Existing technical means generally use the following steps to optimize the pass rate of key sieve apertures of AC-13 asphalt mixture:

[0004] (1) The standard usage of three types of aggregates, 10-15 mm, 5-10 mm, and 3-5 mm, is determined through the target mix ratio of AC-13 asphalt mixture;

[0005] (2) 5-10 mm aggregates at standard dosage, standard dosage ±1%, standard dosage ±2%, and standard dosage ±3% were added to 10-15 mm aggregates at standard dosage, and the filling density of the mixed aggregates at different proportions was tested. The target ratio of the two specifications of aggregates, 5-10 mm aggregate and 10-15 mm aggregate, was determined based on the principle of maximum filling density.

[0006] (3) adding the standard amount, standard amount ±1%, standard amount ±2%, and standard amount ±3% of 3-5 mm aggregate to the optimal mixed aggregate of 5-10 mm aggregate and 10-15 mm aggregate obtained in step (2), respectively, and testing the filling density of the mixed aggregates in different proportions. The target proportions of the three specifications of aggregate, 3-5 mm aggregate, 5-10 mm aggregate, and 10-15 mm aggregate, are determined based on the principle of maximum filling density;

[0007] (4) Using sieving tests to determine the standard particle size composition of three types of aggregates: 10-15 mm, 5-10 mm, and 3-5 mm. Calculate the change in the passing rate of 9.5 mm sieve openings, 4.75 mm sieve openings, and 2.36 mm sieve openings for each 1% change in the proportion of the three types of aggregates.

[0008] (5) According to the result of step (4), the target ratios of the three aggregate sizes of 3-5 mm, 5-10 mm, and 10-15 mm are converted to obtain the optimized pass rates of 9.5 mm sieve hole, 4.75 mm sieve hole, and 2.36 mm sieve hole.

[0009] However, the existing technical means have the following deficiencies:

[0010] (1) Packing density is a volumetric index, not a mechanical index, and cannot characterize the mechanical properties of the aggregate structure of AC-13 asphalt mixture. As a result, the optimization results of the key sieve holes of AC-13 asphalt mixture do not match the optimal value of the mechanical strength of AC-13 asphalt mixture, making it difficult to optimize the mechanical properties of the aggregate structure of AC-13 asphalt mixture. Packing density is used to evaluate the aggregate structure of AC-13 asphalt mixture because existing indoor test methods are difficult to directly measure the mechanical properties of the aggregate skeleton in the aggregate mixture.

[0011] (2) A large number of tests are required, resulting in losses in material costs, labor costs and time costs.

[0012] Therefore, there is an urgent need for an optimization method for the key sieve hole pass rate of coarse aggregate in AC-13 mixture to improve the above problems. Summary of the Invention

[0013] To address the above issues, this application proposes a method for optimizing the pass rate of key sieve holes of coarse aggregate in AC-13 mixture to improve the mechanical properties of the coarse aggregate skeleton structure of AC-13 asphalt mixture, thereby enhancing the mechanical strength of AC-13 asphalt mixture and achieving the purpose of reducing cement dosage and controlling cracking. The method comprises the following steps:

[0014] S1. Determine the standard particle size composition of aggregate according to standard methods, and use PFC 2D Generate a closed rectangular area;

[0015] S2. Calculate the area of ​​the standard particle size components in the aggregate, create and store polygonal information;

[0016] S3, generating circular particles in the closed rectangular area, converting the aggregate polygon information into coarse aggregate units, and completing the generation of the aggregate mixture model;

[0017] S4. Determine the standard amount of aggregate and generate aggregate mixture models with different proportions to control the sieve pass rate;

[0018] S5. Assign elastic modulus and Poisson's ratio to the aggregate, pressurize the model and monitor the stress;

[0019] S6. During the process of pressurizing and monitoring the force of the model, obtain the contact force, calculate the residual average contact force, perform pressurization and contact force calculation on different aggregate mixture models, and determine the optimal aggregate ratio;

[0020] S7. Optimize the critical sieve hole pass rate of coarse aggregate by optimizing the aggregate ratio.

[0021] Preferably, in S1, a screening test is used to determine the standard particle size composition of three types of aggregates: 10-15 mm aggregate, 5-10 mm aggregate, and 3-5 mm aggregate;

[0022] Utilizing PFC 2D The built-in command "wall" generates two vertical rigid walls and two horizontal rigid walls. The four walls are connected end to end to form a closed rectangular area.

[0023] Preferably, the expression for calculating the area of ​​the standard particle size composition in the aggregate in S2 is:

[0024]

[0025] Where: S i The area of ​​aggregate corresponding to the standard particle size (mm 2 ), P is the proportion of aggregate in the target mix (%), α i is the proportion of aggregate corresponding to the standard particle size in the aggregate (%), ρ is the density of the aggregate (g / cm 3 ), ρ 总 is the composite density of aggregate (g / cm 3 ), i is the i-th standard particle size;

[0026] The expression for creating and storing multilateral information is:

[0027]

[0028] Where: θ i,k and r i,k is the polar angle and radius of the kth aggregate polygon of the standard particle size aggregate, in mm, n k is the number of fixed points of the kth aggregate polygon, λ k is the random number corresponding to the kth aggregate polygon, R 0i R is the average radius of standard size aggregate in 10-15mm aggregate. i It is the difference between the upper and lower limits of the standard particle size aggregate in 10-15mm aggregate;

[0029] Preferably, the specific content of creating and storing the multilateral information is:

[0030] According to formula (2) and formula (3), the aggregate polygon information numbered k for the i-th particle size aggregate in the 10-15 mm aggregate is created. The aggregate polygon information includes ID, centroid coordinates, vertex coordinates. The vertex coordinates are within the closed rectangular area, and the area of ​​each polygon is recorded. When the polygon area reaches S i When stopped, through PFC 2D The built-in command "range" stores the created subset polygon information;

[0031] Several sub-aggregate polygon information constitute aggregate polygon information, and the aggregate polygon information includes 10-15 mm aggregate polygon information, 5-10 mm aggregate polygon information, and 3-5 mm aggregate polygon information.

[0032] Preferably, in S3, circular particles are generated in the closed rectangular area, and the aggregate polygon information is converted into coarse aggregate units to complete the generation of the aggregate mixture model. Specifically, the following steps are performed:

[0033] S301, through PFC 2D The built-in command "generate" generates circular particles with a radius of 0.5mm in a closed rectangular area and fills the closed rectangular area;

[0034] S302, through PFC 2D The built-in command "b_id" searches and reads the coordinates of the aggregate polygon vertex numbered k of the standard particle size aggregate in the aggregate, through PFC 2D The built-in command "line" connects the vertices to get the polygon area, and then passes the PFC 2D The built-in command "clump" combines the particles within the polygonal area into polygonal coarse aggregate units;

[0035] S303, converting all polygonal information of aggregate into corresponding coarse aggregate units;

[0036] S304, through PFC 2D The built-in command "delete" deletes the round particles that are not in the coarse aggregate unit and completes the generation of the aggregate mixture model.

[0037] Preferably, the standard amount of aggregate is determined by the target mix ratio of AC-13 asphalt mixture;

[0038] Control the standard quantity range, generate different aggregate mixture models, and obtain the sieve pass rate after back-calculating the mixture model.

[0039] Preferably, the elastic modulus and Poisson's ratio of the aggregate are assigned to the circular particles within the corresponding aggregate polygon;

[0040] Utilizing PFC 2D The built-in command "Servo-mechanism" applies a servo mechanism to the two vertical walls, applies a vertical downward speed of 1 mm / min to the upper horizontal wall to pressurize the aggregate mixture model, and monitors the force on the wall, stopping when the peak value is reached.

[0041] Preferably, S6 obtains the contact force, calculates the residual average contact force, performs pressurization and contact force calculation on different aggregate mixture models, and determines the optimal aggregate ratio in the following specific contents:

[0042] Utilizing PFC 2D The built-in command "force" obtains the contact force between different aggregate units, calculates the average contact force, and deletes the contact force between aggregate units that is smaller than the average contact force;

[0043] Calculate the average contact force between the remaining aggregate units and record it as the residual average contact force;

[0044] The target proportion of aggregate is determined based on the principle of maximizing the residual average contact force.

[0045] Preferably, the target aggregate ratio is converted to obtain the optimized sieve aperture pass rate.

[0046] Preferably, the length of the vertical rigid wall is 200 mm, and the length of the horizontal rigid wall is 100 mm.

[0047] In summary, compared with traditional technologies, the key sieve hole pass rate optimization method of the AC-13 mixture coarse aggregate of the present invention can directly characterize the mechanical properties of the AC-13 asphalt mixture aggregate structure, so that the optimization results of the key sieve holes of the AC-13 asphalt mixture are matched with the optimal values ​​of the mechanical properties of the AC-13 asphalt mixture, thereby improving the quality of pavement use; at the same time, it reduces indoor tests to a certain extent, reduces the loss of raw material costs, labor costs and time costs, and is conducive to ensuring the construction period and controlling engineering costs.

[0048] The technical method of the present invention is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a step diagram of a method for optimizing the pass rate of key sieve holes of coarse aggregate in an AC-13 mixture according to the present invention. DETAILED DESCRIPTION

[0050] The technical method of the present invention is further described below through the accompanying drawings and embodiments. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and values ​​described in these embodiments do not limit the scope of this application.

[0051] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0052] Technologies, systems, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0053] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0054] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0055] A method for optimizing the pass rate of key sieve holes of coarse aggregate in AC-13 mixture comprises the following steps:

[0056] S1. Determine the standard particle size composition of aggregate according to standard methods, and use PFC 2D Generate a closed rectangular area;

[0057] Furthermore, in S1, the standard particle size composition of three types of aggregates, namely 10-15 mm aggregate, 5-10 mm aggregate, and 3-5 mm aggregate, was determined using a sieving test;

[0058] Utilizing PFC 2D The built-in command "wall" generates two vertical rigid walls and two horizontal rigid walls. The four walls are connected end to end to form a closed rectangular area.

[0059] Furthermore, the length of the vertical rigid wall is 200 mm, and the length of the horizontal rigid wall is 100 mm.

[0060] S2. Calculate the area of ​​the standard particle size components in the aggregate, create and store polygonal information;

[0061] Furthermore, the expression for calculating the area of ​​the standard particle size component in the aggregate in S2 is:

[0062]

[0063] Where: S i The area of ​​aggregate corresponding to the standard particle size (mm 2), P is the proportion of aggregate in the target mix (%), α i is the proportion of aggregate corresponding to the standard particle size in the aggregate (%), ρ is the density of the aggregate (g / cm 3 ), ρ 总 is the composite density of aggregate (g / cm 3 ), i is the i-th standard particle size;

[0064] The expression for creating and storing multilateral information is:

[0065]

[0066] Where: θ i,k and r i,k is the polar angle and radius of the kth aggregate polygon of the standard particle size aggregate, in mm, n k is the number of fixed points of the kth aggregate polygon, λ k is the random number corresponding to the kth aggregate polygon, R 0i R is the average radius of standard size aggregate in 10-15mm aggregate. i It is the difference between the upper and lower limits of the standard particle size aggregate in 10-15mm aggregate;

[0067] Furthermore, the specific contents of creating and storing multilateral information are as follows:

[0068] According to formula (2) and formula (3), the aggregate polygon information numbered k for the i-th particle size aggregate in the 10-15 mm aggregate is created. The aggregate polygon information includes ID, centroid coordinates, vertex coordinates. The vertex coordinates are within the closed rectangular area, and the area of ​​each polygon is recorded. When the polygon area reaches S i When stopped, through PFC 2D The built-in command "range" stores the created subset polygon information;

[0069] Several sub-aggregate polygon information constitute aggregate polygon information, and the aggregate polygon information includes 10-15 mm aggregate polygon information, 5-10 mm aggregate polygon information, and 3-5 mm aggregate polygon information.

[0070] S3, generating circular particles in the closed rectangular area, converting the aggregate polygon information into coarse aggregate units, and completing the generation of the aggregate mixture model;

[0071] Furthermore, in S3, circular particles are generated in the closed rectangular area, and the aggregate polygon information is converted into coarse aggregate units. The specific contents of completing the generation of the aggregate mixture model are as follows:

[0072] S301, through PFC 2DThe built-in command "generate" generates circular particles with a radius of 0.5mm in a closed rectangular area and fills the closed rectangular area;

[0073] S302, through PFC 2D The built-in command "b_id" searches and reads the coordinates of the aggregate polygon vertex numbered k of the standard particle size aggregate in the aggregate, through PFC 2D The built-in command "line" connects the vertices to get the polygon area, and then passes PFC 2D The built-in command "clump" combines the particles within the polygonal area into polygonal coarse aggregate units;

[0074] S303, converting all polygonal information of aggregate into corresponding coarse aggregate units;

[0075] S304, through PFC 2D The built-in command "delete" deletes the round particles that are not in the coarse aggregate unit and completes the generation of the aggregate mixture model.

[0076] S4. Determine the standard amount of aggregate and generate aggregate mixture models with different proportions to control the sieve pass rate;

[0077] Furthermore, the standard amount of aggregate is determined by the target mix ratio of AC-13 asphalt mixture;

[0078] Control the standard quantity range, generate different aggregate mixture models, and obtain the sieve pass rate after back-calculating the mixture model.

[0079] S5. Assign elastic modulus and Poisson's ratio to the aggregate, pressurize the model and monitor the stress;

[0080] Furthermore, the elastic modulus and Poisson's ratio of the aggregate are assigned to the circular particles within the corresponding aggregate polygon;

[0081] Utilizing PFC 2D The built-in command "Servo-mechanism" applies a servo mechanism to the two vertical walls, applies a vertical downward speed of 1 mm / min to the upper horizontal wall to pressurize the aggregate mixture model, and monitors the force on the wall, stopping when the peak value is reached.

[0082] S6. During the process of pressurizing and monitoring the force of the model, obtain the contact force, calculate the residual average contact force, perform pressurization and contact force calculation on different aggregate mixture models, and determine the optimal aggregate ratio;

[0083] Furthermore, S6 obtains the contact force, calculates the residual average contact force, performs pressurization and contact force calculations on different aggregate mixture models, and determines the optimal aggregate ratio. The specific contents are as follows:

[0084] Utilizing PFC 2D The built-in command "force" obtains the contact force between different aggregate units, calculates the average contact force, and deletes the contact force between aggregate units that is smaller than the average contact force;

[0085] Calculate the average contact force between the remaining aggregate units and record it as the residual average contact force;

[0086] The target proportion of aggregate is determined based on the principle of maximizing the residual average contact force.

[0087] S7. Optimize the critical sieve hole pass rate of coarse aggregate by optimizing the aggregate ratio.

[0088] Furthermore, the target aggregate ratio is converted to obtain the optimized sieve hole pass rate.

[0089] Example 1

[0090] Step 1: According to the standard method, the standard particle size composition of three types of aggregates, namely 10-15 mm aggregate, 5-10 mm aggregate, and 3-5 mm aggregate, is determined by screening test;

[0091] Step 2: Utilize PFC 2D The built-in command "wall" generates two vertical rigid walls with a length of 200 mm and two horizontal rigid walls with a length of 100 mm. The four walls are connected end to end to form a closed rectangular area.

[0092] Step 3, based on the standard particle size composition of 10-15 mm aggregate obtained in step 1, calculate the area of ​​the i-th particle size aggregate in the 10-15 mm aggregate according to formula (1);

[0093]

[0094] Where: S i is the area of ​​aggregate corresponding to the i-th particle size (mm 2 ), P is the proportion of 10-15mm aggregate in the target mix (%), α i is the proportion of the aggregate corresponding to the i-th particle size in the 10-15 mm aggregate (%), ρ is the density of the 10-15 mm aggregate (g / cm 3 ), ρ 总 The composite density of three types of aggregates (g / cm2): 10-15mm aggregate, 5-10mm aggregate, and 3-5mm aggregate 3 );

[0095] Step 4: Create the aggregate polygon information numbered k for the i-th particle size aggregate in the 10-15 mm aggregate according to formula (2) and formula (3). The aggregate polygon information includes ID, centroid coordinates, and vertex coordinates. The vertex coordinates must be within the closed rectangular area created in step 2, and the area of ​​each polygon is recorded. When the polygon area reaches S i Stop when PFC is used 2D The built-in command "range" stores the created aggregate polygon information;

[0096]

[0097] Where: θ i,k and r i,k The polar angle and radius of the kth aggregate polygon of the i-th particle size aggregate in the 10-15mm aggregate, in mm, n k is the fixed point number of the kth aggregate polygon, which is a random natural number between 4 and 8. k is the random number corresponding to the kth aggregate polygon, and the random number is a real number between 0 and 1. 0i is the average radius of the i-th size aggregate in the 10-15 mm aggregate, R i It is the difference between the upper limit and the lower limit of the particle size of the i-th particle size aggregate in the 10-15mm aggregate.

[0098] Step 5: Repeat steps 3 and 4 to create and store all aggregate polygon information in the 10-15 mm aggregate.

[0099] Step 6: Using the same method as steps 3, 4, and 5, create and store aggregate polygon information corresponding to 5-10 mm aggregate and 3-5 mm aggregate in sequence;

[0100] Step 7, through PFC 2D The built-in command "generate" generates circular particles with a radius of 0.5 mm in step 2 and fills the closed rectangular area generated in step 2;

[0101] Step 8, through PFC 2D The built-in command "b_id" searches and reads the coordinates of the vertex of the aggregate polygon numbered k of the i-th size aggregate in the 10-15mm aggregate, through PFC 2D The built-in command "line" connects the vertices to get the polygon area, and then passes the PFC 2D The built-in command "clump" combines the particles within the polygonal area into polygonal coarse aggregate units;

[0102] Step 9: Convert all polygonal information of 10-15 mm aggregate into corresponding coarse aggregate units according to step 8, thereby completing the generation of 10-15 mm aggregate;

[0103] Step 10: Using the same method as steps 8 and 9, convert all polygon information of 5-10mm aggregate and 3-5mm aggregate into corresponding coarse aggregate units. 2D The built-in command "delete" deletes the round particles that are not in any coarse aggregate unit, thus completing the generation of the aggregate mixture model;

[0104] Step 11: Determine the standard amount of 10-15mm aggregate, 5-10mm aggregate, and 3-5mm aggregate using the target mix ratio of AC-13 asphalt mixture. According to steps 3 to 10, the standard amount of 10-15mm aggregate: 5-10mm aggregate: 3-5mm aggregate is equal to: standard amount: standard amount, standard amount: standard amount ± 1%: standard amount, respectively. 1%, standard amount: standard amount ± 2%: standard amount 2%, generate different aggregate mixture models; the corresponding 9.5mm sieve hole, 4.75mm sieve hole, and 2.36mm sieve hole pass rates of each mixture model after back calculation should be controlled within 75-86%, 41-51%, and 26-31%;

[0105] Step 12: assign the elastic modulus and Poisson's ratio of 10-15mm aggregate, 5-10mm aggregate, and 3-5mm aggregate to the circular particles within the corresponding aggregate polygon; use PFC 2D The built-in command "Servo-mechanism" applies a servo mechanism to the two vertical walls generated in step 2, applies a vertical downward velocity of 1 mm / min to the upper horizontal wall to pressurize the aggregate mixture model, and monitors the force on the wall, stopping when the peak force is reached.

[0106] Step 13: Utilize PFC 2D The built-in command "force" obtains the contact force between different aggregate units and calculates the average contact force. The contact force between aggregate units that is smaller than the average contact force is deleted, and the average contact force of the remaining aggregate units is calculated and recorded as the residual average contact force.

[0107] Step 14, performing steps 12 and 13 on the different aggregate mixture models described in step 11, respectively, and determining target proportions of three sizes of aggregates: 10-15 mm aggregate, 5-10 mm aggregate, and 3-5 mm aggregate, based on the principle of maximizing the residual average contact force;

[0108] In step 15, the target ratios of the three aggregate sizes of 3-5 mm, 5-10 mm, and 10-15 mm are converted to obtain the optimized pass rates of 9.5 mm sieve holes, 4.75 mm sieve holes, and 2.36 mm sieve holes, thereby optimizing the pass rate of the key sieve holes of the coarse aggregate of the AC-13 asphalt mixture.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical method of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that they can still modify or replace the technical method of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical method to deviate from the spirit and scope of the technical method of the present invention.

Claims

1. A method for optimizing the pass rate of key sieve holes of coarse aggregate in AC-13 mixture, characterized in that: The following steps are involved: S1. Determine the standard particle size composition of aggregate according to standard methods, and use PFC 2D Generate a closed rectangular area; S2. Calculate the area of ​​the standard particle size components in the aggregate, create and store polygonal information; S3, generating circular particles in the closed rectangular area, converting the aggregate polygon information into coarse aggregate units, and completing the generation of the aggregate mixture model; S4. Determine the standard amount of aggregate and generate aggregate mixture models with different proportions to control the sieve pass rate; S5. Assign elastic modulus and Poisson's ratio to the aggregate, and pressurize the model to monitor the stress; S6. During the process of pressurizing and monitoring the force of the model, the contact force is obtained, the residual average contact force is calculated, pressurization and contact force calculation are performed on different aggregate mixture models, and the optimal aggregate ratio is determined; S7. Optimize the critical sieve hole pass rate of coarse aggregate by optimizing the aggregate ratio.

2. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 1, characterized in that: In S1, the standard particle size composition of three types of aggregates, 10-15 mm aggregate, 5-10 mm aggregate, and 3-5 mm aggregate, was determined by sieving test; Utilizing PFC 2D The built-in command "wall" creates two vertical rigid walls and two horizontal rigid walls. The four walls are connected end to end to form a closed rectangular area.

3. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 2, characterized in that: The expression for calculating the area of ​​the standard particle size component in the aggregate in S2 is: Where: S i The area of ​​aggregate corresponding to the standard particle size is mm 2 , P is the proportion of aggregate in the target mix ratio, α i is the proportion of aggregate corresponding to the standard particle size in the aggregate, ρ is the density of the aggregate g / cm 3 ,ρ 总 is the composite density of aggregate g / cm 3 , i is the i-th standard particle size; The expression for creating and storing multilateral information is: Where: θ i,k and r i,k is the polar angle and radius of the kth aggregate polygon of the standard particle size aggregate, in mm, n k is the number of fixed points of the kth aggregate polygon, λ k is the random number corresponding to the kth aggregate polygon, R 0i R is the average radius of standard size aggregate in 10-15mm aggregate. i It is the difference between the upper and lower limits of the standard particle size aggregate in 10-15mm aggregate.

4. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 3, characterized in that: The specific contents of creating and storing multilateral information are: According to formula (2) and formula (3), the aggregate polygon information numbered k for the i-th particle size aggregate in the 10-15 mm aggregate is created. The aggregate polygon information includes ID, centroid coordinates, vertex coordinates. The vertex coordinates are within the closed rectangular area, and the area of ​​each polygon is recorded. When the polygon area reaches S i When stopped, through PFC 2D The built-in command "range" stores the created subset polygon information; Several sub-aggregate polygon information constitute aggregate polygon information, and the aggregate polygon information includes 10-15 mm aggregate polygon information, 5-10 mm aggregate polygon information, and 3-5 mm aggregate polygon information.

5. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 4, characterized in that: In S3, circular particles are generated in the closed rectangular area, and the aggregate polygon information is converted into coarse aggregate units to complete the generation of the aggregate mixture model. The specific contents are as follows: S301, through PFC 2D The built-in command "generate" generates circular particles with a radius of 0.5mm in a closed rectangular area and fills the closed rectangular area; S302, through PFC 2D The built-in command "b_id" searches and reads the coordinates of the aggregate polygon vertex numbered k of the standard particle size aggregate in the aggregate, through PFC 2D The built-in command "line" connects the vertices to get the polygon area, and then passes PFC 2D The built-in command "clump" combines particles within the polygonal region into polygonal coarse aggregate units; S303, converting all polygonal information of aggregate into corresponding coarse aggregate units; S304, through PFC 2D The built-in command "delete" deletes the round particles that are not in the coarse aggregate unit and completes the generation of the aggregate mixture model.

6. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 5, characterized in that: Determine the standard amount of aggregates of different specifications through the actual target mix ratio of AC-13 asphalt mixture; Control the standard quantity range, generate different aggregate mixture models, and obtain the sieve pass rate after back-calculating the mixture model.

7. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 6, characterized in that: Assign the elastic modulus and Poisson's ratio of the aggregate to the circular particles within the corresponding aggregate polygon; Utilizing PFC 2D The built-in command "Servo-mechanism" applies a servo mechanism to the two vertical walls, applies a vertical downward velocity of 1 mm / min to the upper horizontal wall to pressurize the aggregate mixture model, and monitors the force on the wall, stopping when the peak force is reached.

8. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 7, characterized in that: S6 obtains the contact force, calculates the residual average contact force, performs pressurization and contact force calculations on different aggregate mixture models, and determines the optimal aggregate ratio. The specific contents are: Utilizing PFC 2D The built-in command "force" obtains the contact force between different aggregate units, calculates the average contact force, and deletes the contact force between aggregate units that is smaller than the average contact force; Calculate the average contact force between the remaining aggregate units and record it as the residual average contact force; The target proportion of aggregate is determined based on the principle of maximizing the residual average contact force.

9. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 8, characterized in that: Convert the target aggregate ratio to obtain the optimized sieve pass rate.

10. The method for optimizing the pass rate of key sieve holes of coarse aggregate of AC-13 mixture according to claim 2, characterized in that: The length of the vertical rigid wall is 200 mm, and the length of the horizontal rigid wall is 100 mm.

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