Evaluation method of load transfer behavior of asphalt mixture based on quantification of force chain characteristics

Abstract

The present invention discloses a method for evaluating the load transfer behavior of asphalt mixture based on the quantification of force chain characteristics, comprising: (1) establishing a two-dimensional discrete element model of asphalt mixture according to the composition of the asphalt mixture; (2) performing a virtual bearing test on the discrete element model of the asphalt mixture to obtain contact information between aggregates and aggregate information; (3) setting a force chain formation standard according to the contact information between aggregates; (4) identifying the asphalt mixture force chains one by one based on the set force chain formation standard; (5) defining a force chain characteristic quantification index; (6) calculating the force chain characteristic quantification index; (7) evaluating the external load transfer behavior of the asphalt mixture according to the calculation result of the force chain characteristic quantification index; the present invention realizes the accurate evaluation of the load transfer behavior of the asphalt mixture from the perspective of the quantification of force chain characteristics.

Description

Technical Field

[0001] The invention relates to an evaluation method for load transfer behavior of asphalt mixture, and in particular to an evaluation method for load transfer behavior of asphalt mixture based on quantification of force chain characteristics. Background Art

[0002] Under the action of external load, the load transfer behavior of asphalt mixture directly affects the bearing capacity of asphalt pavement. At present, the load transfer behavior of asphalt mixture is mostly evaluated through statistical analysis of contact force between aggregates, which has not yet reflected the load transfer behavior. Granular material mechanics believes that under the action of external load, many load transfer paths with different strengths will be formed inside the asphalt mixture, which are called force chains. Therefore, the force chain characteristics determine the load transfer behavior of asphalt mixture. Although researchers in the field of pavement material research have begun to use force chains to study asphalt mixtures, and related research has achieved certain new insights. However, related research only describes the force chain structure from a qualitative perspective and lacks quantitative analysis. Summary of the invention

[0003] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide an evaluation method for the load transfer behavior of asphalt mixture based on the quantification of force chain characteristics, so as to accurately evaluate the load transfer behavior of asphalt mixture from the perspective of quantification of force chain characteristics.

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

[0005] The present invention provides an evaluation method for load transfer behavior of asphalt mixture based on quantification of force chain characteristics, comprising the following steps:

[0006] (1) According to the composition of asphalt mixture, a two-dimensional discrete element model of asphalt mixture is established;

[0007] (2) Setting a virtual bearing plate on the two-dimensional discrete element model of asphalt mixture established in step (1), performing a virtual bearing test on the two-dimensional discrete element model of asphalt mixture, and obtaining aggregate contact information and aggregate information that meet the requirement of being greater than or equal to the normal contact force threshold; the aggregate contact information includes the normal contact force value between aggregates, the contact number, and the coordinates of aggregates in contact with each other; the aggregate information includes the aggregate coordinates, the aggregate number, and the particle size information of the aggregate; and establishing aggregate sets MAM and MAAM based on the aggregate information;

[0008] (3) according to the contact information between aggregates obtained in step (2), setting the force chain formation standard;

[0009] (4) searching for force chains according to the force chain formation standard set in step (3) to obtain a plurality of force chains;

[0010] (5) performing repeated force chain definition on the multiple force chains obtained in step (4), performing repeated force chain search, and deleting repeated force chains in the force chain structure;

[0011] (6) defining quantitative indexes of force chain characteristics for the force chain after deleting the duplicate force chain in step (5);

[0012] (7) calculating the characteristic quantitative index value of the force chain in step (6) according to the definition of step (6);

[0013] (8) Based on the calculation results of the quantitative index of the force chain characteristics obtained in step (7), the external load transfer behavior of the asphalt mixture is evaluated.

[0014] Preferably, in step (1), when establishing the two-dimensional discrete element model of asphalt mixture, it is assumed that the aggregate particles of the asphalt mixture are round.

[0015] Preferably, the normal contact force threshold in step (2) is the average value of the normal contact force between aggregates in the two-dimensional discrete element model of asphalt mixture.

[0016] Preferably, the force chain formation standard in step (3) includes:

[0017] (31) One force chain is searched at a time, and the starting aggregate of the force chain is determined according to the order of the aggregate y coordinates from large to small;

[0018] (32) The next level of aggregates is the aggregate that is in contact with the current aggregate in this force chain and whose height is less than or equal to the height of the current aggregate;

[0019] (33) The angle between two adjacent normal contacts forming a force chain is less than or equal to θ, where θ is the angle value;

[0020] (34) The number of aggregate particles in the force chain is greater than or equal to N, where N is a positive integer.

[0021] Preferably, in step (4), the search process of launching a force chain search according to the force chain formation standard includes:

[0022] (41) Traverse the MAM set, select the aggregate with the largest y-axis coordinate value as the starting aggregate, increase the number of aggregate particles by 1, and delete the starting aggregate from the MAM set;

[0023] (42) Determine whether there are aggregates in the set MAAM that are in contact with the starting aggregates. If so, establish an aggregate set MBM for all aggregates that are in contact with the starting aggregates. If not, go to step (41).

[0024] (43) Traverse the set MBM, determine the aggregate at this level, and increase the number of aggregate particles by 1;

[0025] (44) If, in the set MAAM, no other aggregates are found in contact with the aggregates of this level except the starting aggregate, then go to step (45); if there are other aggregates in contact with the aggregates of this level, then calculate the angle between the two adjacent normal contacts of the starting aggregate, the aggregates of this level, and each corresponding aggregate of the next level in contact, and go to step (46);

[0026] (45) Determine whether the number of aggregate particles on the force chain is greater than or equal to N. If the requirement is met, save the force chain information to the force chain array FCMA; if not, there is no need to save, and further determine whether the set MBM has been traversed. If the traversal is completed, go to step (48); if the traversal is not completed, go to step (43);

[0027] (46) If all the calculated normal contact angles are greater than θ, go to step (47); if there is a normal contact angle less than or equal to θ, the aggregate corresponding to the minimum angle is used as the next level aggregate, and the number of aggregate particles is increased by 1. The aggregate of this level is defined as the new starting aggregate, and the aggregate of the next level is defined as the new aggregate of this level, and go to step (44);

[0028] (47) Determine whether the number of aggregate particles on the force chain is greater than or equal to N. If the requirement is met, save the force chain information to the force chain array FCMA; if not, no need to save. And further determine whether the set MBM has been traversed, then go to step (48), otherwise go to step (43);

[0029] (48) Determine whether the aggregates in the set MAM have been traversed. If not, go to step (41); if traversed, end the search for all force chains.

[0030] Preferably, in step (5), the repeated force chain structure is defined as the existence of two force chain structures. If the shorter force chain is completely consistent with a continuous part of another force chain, the two force chains are considered to be repeated force chains, and the shorter force chain should be deleted.

[0031] Preferably, in step (5), the specific process of repeating the force chain search includes:

[0032] (A) All force chains searched in step (4) are recorded as force chain array FCMA. At the same time, the force chain array FCMA is copied to the force chain array FCMB. At the same time, the duplicate force chains to be deleted are stored in the force chain array YSC.

[0033] (B) Traverse the force chain array FCMA and determine the analysis object, which is recorded as this force chain;

[0034] (C) Determine whether this force chain belongs to the force chain array YSC. If so, go to step (B); otherwise, go to step (D);

[0035] (D) traverse the force chain array FCMB and determine the comparison object, which is recorded as the comparison force chain;

[0036] (E) Determine whether the position number of the current force chain in the array FCMA is the same as the position number of the comparison force chain in the array FCMB. If they are the same, proceed to step (J); if they are not the same, proceed to step (F);

[0037] (F) Determine whether the comparison force chain belongs to the force chain array YSC. If not, go to step (G); if yes, compare the length relationship between the current force chain and the comparison force chain. If the length of the comparison force chain is longer than that of the current force chain, go to step (G); otherwise, go to step (J);

[0038] (G) judging and comparing the force chain and the current force chain, if the shorter force chain is completely consistent with a continuous part of the other force chain, proceeding to step (H); otherwise, proceeding to step (J);

[0039] (H) If the force chain is marked as a repeated force chain, the information of the force chain is saved into the force chain array YSC, and the process goes to step (I); if the comparison force chain is marked as a repeated force chain, the information of the comparison force chain is saved into the force chain array YSC, and the process goes to step (J);

[0040] (I) Determine whether the force chain array FCMA has been traversed completely. If not, go to step (B); if traversal is completed, end the search;

[0041] (J) Determine whether the force chain array FCMB has been traversed. If the force chain array FCMB has been traversed, determine whether the force chain array FCMA has been traversed. If the force chain array FCMA has not been traversed, go to step (B); if the force chain array FCMA has been traversed, end the search; if the force chain array FCMB has not been traversed, go to step (D).

[0042] Preferably, in step (6), the defined quantitative indicators of the force chain characteristics include the force chain length and the force chain direction angle; the length of a single force chain is defined as the sum of the particle sizes of all aggregates on the single force chain; the force chain direction angle is defined as the angle between the vector formed with the centroids of the starting and ending aggregates on the single force chain as the starting and ending coordinates and the horizontal x-axis direction.

[0043] Preferably, the step (7) specifically comprises:

[0044] Firstly, the number of force chains of asphalt mixture, the length of each force chain and the direction angle are obtained; then two types of indexes, force chain length distribution and force chain shape distribution, are given and the index values ​​are calculated;

[0045] The force chain length distribution index includes the total length of the force chain L sum , average force chain length Lavg And the proportion of force chains whose length is less than or equal to the height of the virtual specimen P l≤h , and the calculation formulas are as follows:

[0046]

[0047]

[0048]

[0049] in:

[0050] N: The total number of force chains generated inside the asphalt mixture under load;

[0051] l i : the length of the i-th force chain in asphalt mixture, in m;

[0052] L sum : Total length of the force chain of asphalt mixture, in m;

[0053] N l≤h : The total number of force chains whose length is less than or equal to the height of the virtual specimen;

[0054] P l≤h : The proportion of force chains whose length is less than or equal to the height of the virtual specimen;

[0055] The force chain morphology distribution index includes the average collimation coefficient of the force chain and the average direction angle of the force chain, and the calculation formulas thereof are as follows:

[0056]

[0057]

[0058]

[0059]

[0060] in:

[0061] α p : The angle between the pth adjacent normal contacts on the ith force chain;

[0062] M: total number of adjacent contacts;

[0063] δ i : the value of the collimation coefficient of the i-th force chain;

[0064] δ avg : The average collimation coefficient of the asphalt mixture force chain;

[0065] Coordinate (x A,y A ) and (x B ,y B ) are the position coordinates of aggregates A and B respectively;

[0066] θ i : The direction angle of the i-th force chain, between 0 and 180°;

[0067] θ avg : Average direction angle of force chain of asphalt mixture.

[0068] The beneficial effects of the present invention are:

[0069] The present invention is based on the defined quantitative index of force chain characteristics and can effectively distinguish the load transfer behaviors of different types of asphalt mixtures from the perspective of force chain characteristics quantification, and can overcome the deficiency of existing methods that cannot reflect load transfer behaviors. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0071] Figure 1 Schematic diagram of the angle between adjacent normal directions of the force chain in the present invention;

[0072] Figure 2 is the asphalt mixture gradation curve of the present invention;

[0073] Figure 3 A discrete element model of asphalt mixture established for the present invention;

[0074] Figure 4 It is a schematic diagram of a virtual test of asphalt mixture of the present invention;

[0075] Figure 5 It is the force chain search flow chart of the present invention;

[0076] Figure 6 A flow chart for searching for a repetitive force chain of the present invention;

[0077] Figure 7 This is a schematic diagram of the force chain structure of AC10 asphalt mixture;

[0078] Figure 8 This is a schematic diagram of the force chain structure of SMA10 asphalt mixture;

[0079] Fig. 9 It is a schematic diagram of the force chain direction angle in the present invention. DETAILED DESCRIPTION

[0080] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] like Figures 1 to 9 As shown, this embodiment provides a method for evaluating the load transfer behavior of asphalt mixture based on the quantification of force chain characteristics, which mainly includes the following steps:

[0082] (1) According to the material composition of asphalt mixture and the assumption of circular aggregate, a two-dimensional discrete element model of asphalt mixture is established; Figure 2 The aggregate gradation curves of AC10 and SMA10 asphalt mixtures in the paper are used to establish a discrete element model of asphalt mixture with a width of 40 mm and a length of 300 mm using PFC2D software. Figure 3 As shown, Figure 3 (a) is the AC10 discrete element model generation process. Figure 3 (b) The discrete element model generation process of SMA10;

[0083] (2) A virtual bearing plate is set on the asphalt mixture discrete element model, and a virtual bearing experiment is performed on the asphalt mixture discrete element model, such as Figure 4 As shown; the contact information between aggregates and aggregate information that meet the requirement of being greater than or equal to the normal contact force threshold are obtained; the contact information includes: the normal contact force value between aggregates, the contact number and the coordinates of the aggregates in contact with each other; the aggregate information includes: the aggregate coordinates, the aggregate number and the particle size information of the aggregate; the normal contact force threshold is the average value of the normal contact force between aggregates in the asphalt mixture discrete element model, and at the same time, based on the aggregate information, the aggregate sets MAM and MAAM are established respectively;

[0084] (3) According to the contact information between aggregates, a force chain formation standard is set; the force chain formation standard includes the following:

[0085] Criterion 1: Search one force chain at a time and determine the starting aggregate of the force chain according to the order of the aggregate y coordinates from large to small;

[0086] Criterion 2: The next level aggregate is the aggregate that is in contact with the current aggregate in this force chain and whose height is less than or equal to the height of the current aggregate;

[0087] Criterion 3: The angle between two adjacent normal contacts forming a force chain is less than or equal to θ, and in this embodiment, θ = 45°;

[0088] Criterion 4: The number of aggregate particles in the force chain is greater than or equal to N. In this embodiment, N = 3;

[0089] (4) Based on the Matlab software platform and according to the force chain formation standard set in this embodiment, an algorithm is compiled to carry out force chain search in the asphalt mixture discrete element model to obtain the force chain structure of the asphalt mixture. The force chain search process is as follows: Figure 5 As shown; the force chain search algorithm process is as follows:

[0090] Step ①: Traverse the MAM set, select the aggregate with the largest y-axis coordinate value as the starting aggregate, add 1 to the number of aggregate particles, and delete the starting aggregate from the MAM set;

[0091] Step ②: Determine whether there are aggregates in the set MAAM that are in contact with the starting aggregates. If so, create an aggregate array MBM for all aggregates that are in contact with the starting aggregates; if not, go to step ①;

[0092] Step ③: Traverse the set MBM, determine the aggregate at this level, and increase the number of aggregate particles by 1;

[0093] Step ④: If, in the set MAAM, no other aggregates are found in contact with the aggregates of this level except the starting aggregate, then go to step ⑤; if there are other aggregates in contact with the aggregates of this level, then calculate the angle between the two adjacent normal contacts of the starting aggregate, the aggregates of this level, and each corresponding aggregate of the next level in contact, and go to step ⑥;

[0094] Step ⑤: Determine whether the number of aggregate particles on the force chain is greater than or equal to 3. If the requirement is met, save the force chain information to the force chain array FCMA; if not, no need to save. And further determine whether the set MBM has been traversed. If the traversal is completed, go to step ⑧; otherwise, go to step ③;

[0095] Step ⑥: If all the calculated normal contact angles are greater than 45°, go to step ⑦; if there is a normal contact angle less than or equal to 45°, the aggregate corresponding to the minimum angle is used as the next level aggregate, and the number of aggregate particles is increased by 1; the current level aggregate is defined as the new starting aggregate, and the next level aggregate is defined as the new current level aggregate, and go to step ④;

[0096] Step ⑦: Determine whether the number of aggregate particles on the force chain is greater than or equal to 3. If the requirement is met, save the force chain information to the force chain array FCMA; if not, no need to save; and further determine whether the set MBM has been traversed, then go to step ⑧, otherwise go to step ③;

[0097] Step ⑧: Determine whether the aggregates in the MAM set have been traversed. If not, go to step ①; if yes, end the search for all force chains;

[0098] (5) Define a repeated force chain structure, and define a repeated force chain structure as the existence of two force chain structures. If the shorter force chain is completely consistent with a continuous part of another force chain, the two force chains are considered to be repeated force chains, and the shorter force chain should be deleted. Based on the definition of repeated force chains and the Matlab software platform, an algorithm is compiled to identify the repeated force chain structure in the above force chain; the repeated force chain structure identification is as follows: Figure 6 As shown in the figure, after force chain search and repeated force chain deletion, the force chain structures of AC10 and SMA10 are obtained as follows: Figure 7 and Figure 8 As shown, Figure 7 (a) is a schematic diagram of all aggregate particles of AC10. Figure 7 (b) is a schematic diagram of the aggregate particles of AC10 located on the force chain; Figure 8 (a) is a schematic diagram of all aggregate particles of SMA10. Figure 8 (b) is a schematic diagram of the aggregate particles of SMA10 located on the force chain; the specific identification process of the repeated force chain is as follows:

[0099] Step A: All force chains obtained by the above search process are recorded as force chain array FCMA. At the same time, the force chain array FCMA is copied to the force chain array FCMB. At the same time, the duplicate force chains to be deleted are stored in the force chain array YSC.

[0100] Step B: traverse the force chain array FCMA and determine the analysis object, which is recorded as this force chain;

[0101] Step C: Determine whether this force chain belongs to the force chain array YSC. If so, go to step B; otherwise, go to step D.

[0102] Step D: traverse the force chain array FCMB and determine the comparison object, which is recorded as the comparison force chain;

[0103] Step E: Determine whether the position number of the current force chain in the array FCMA is the same as the position number of the comparison force chain in the array FCMB. If they are the same, proceed to step J; if they are not the same, proceed to step F;

[0104] Step F: Determine whether the comparison force chain belongs to the force chain array YSC. If not, go to step G. If yes, compare the length relationship between the current force chain and the comparison force chain. If the length of the comparison force chain is longer than that of the current force chain, go to step G. Otherwise, go to step J.

[0105] Step G: judge and compare the force chain with the current force chain. If the shorter force chain is completely consistent with a continuous part of the other force chain, proceed to step H; otherwise, proceed to step J.

[0106] Step H: If the force chain is marked as a repeated force chain, the information of the force chain is saved into the force chain array YSC, and the process goes to step I; if the comparison force chain is marked as a repeated force chain, the information of the comparison force chain is saved into the force chain array YSC, and the process goes to step J;

[0107] Step I: Determine whether the force chain array FCMA has been traversed. If not, go to step B; if it has been traversed, end the search;

[0108] Step J: Determine whether the force chain array FCMB has been traversed. If the force chain array FCMB has been traversed, determine whether the force chain array FCMA has been traversed. If the force chain array FCMA has not been traversed, go to step B; if the force chain array FCMA has been traversed, end the search; if the force chain array FCMB has not been traversed, go to step D;

[0109] (6) Define the quantitative index of force chain characteristics. The quantitative index of force chain characteristics specifically includes the length of the force chain and the direction angle of the force chain. The length of a single force chain is defined as the sum of the particle sizes of all aggregates on the single force chain. The direction angle of the force chain is defined as the angle between the vector formed by the centroids of the starting and ending aggregates on the single force chain as the starting and ending coordinates and the horizontal x-axis direction, such as Fig. 9 As shown;

[0110] (7) Calculate the quantitative index of force chain characteristics. First, obtain the number of force chains in the asphalt mixture, the length of each force chain, and the direction angle. Then, give two types of indexes: force chain length distribution and force chain shape distribution, and calculate the values ​​of each index.

[0111] The force chain length distribution index includes the total length of the force chain L sum , average force chain length L avg And the proportion of force chains whose length is less than or equal to the height of the virtual specimen P l≤h , and the calculation formulas are as follows:

[0112]

[0113]

[0114]

[0115] in:

[0116] N: The total number of force chains generated inside the asphalt mixture under load;

[0117] l i : the length of the i-th force chain in asphalt mixture, in m;

[0118] L sum : Total length of the force chain of asphalt mixture, in m;

[0119] N l≤h : The total number of force chains whose length is less than or equal to the height of the virtual specimen;

[0120] P l≤h : The proportion of force chains whose length is less than or equal to the height of the virtual specimen;

[0121] The force chain morphology distribution index includes the average collimation coefficient of the force chain and the average direction angle of the force chain, and the calculation formulas thereof are as follows:

[0122]

[0123]

[0124]

[0125]

[0126] in:

[0127] α p : The angle between the pth adjacent normal contacts on the ith force chain;

[0128] M: total number of adjacent contacts;

[0129] δ i : the collimation coefficient value of the i-th force chain;

[0130] δ avg : The average collimation coefficient of the asphalt mixture force chain;

[0131] Coordinate (x A ,y A ) and (x B ,y B ) are the position coordinates of aggregates A and B respectively;

[0132] θ i : The direction angle of the i-th force chain, between 0 and 180°;

[0133] θ avg : Average direction angle of force chain of asphalt mixture.

[0134] In this embodiment, the calculation results of the two major types of indicators are shown in the following table:

[0135]

[0136] From the results in the table, it can be seen that the total length of the force chain of AC10 asphalt mixture is the longest, the number of force chains is also the largest, and the average length of the force chain is smaller; therefore, compared with SMA10, AC10 exhibits a weaker ability to transfer external loads. From the force chain morphology distribution index, it can be seen that the average collimation coefficient of SMA10 is greater than that of AC10, indicating that the force chain of SMA10 is closer to a straight line and has better stability when transferring loads. From the perspective of the average force chain direction, AC10 is greater than SMA10, indicating that the force chain morphology of AC10 is closer to a trapezoid, SMA10 is closer to a rectangle, and SMA10 has a higher load transfer efficiency. This conclusion shows the rationality and scientificity of the evaluation of the load transfer behavior of asphalt mixtures based on the quantitative index of force chain characteristics in this embodiment.

[0137] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. The load transfer behavior evaluation method of asphalt mixture based on the quantification of force chain characteristics is characterized by: The following steps are involved: (1) According to the composition of asphalt mixture, a two-dimensional discrete element model of asphalt mixture is established; (2) Setting a virtual bearing plate on the two-dimensional discrete element model of asphalt mixture established in step (1), performing a virtual bearing test on the two-dimensional discrete element model of asphalt mixture, and obtaining aggregate contact information and aggregate information that meet the requirement of being greater than or equal to the normal contact force threshold; the aggregate contact information includes the normal contact force value between aggregates, the contact number, and the coordinates of aggregates in contact with each other; the aggregate information includes the aggregate coordinates, the aggregate number, and the particle size information of the aggregate; and establishing aggregate sets MAM and MAAM based on the aggregate information; (3) according to the contact information between aggregates obtained in step (2), setting the force chain formation standard; (4) searching for force chains according to the force chain formation standard set in step (3) to obtain a plurality of force chains; (5) performing repeated force chain definition on the multiple force chains obtained in step (4), performing repeated force chain search, and deleting repeated force chains in the force chain structure; (6) defining quantitative indexes of force chain characteristics for the force chain after deleting the duplicate force chain in step (5); (7) calculating the characteristic quantitative index value of the force chain in step (6) according to the definition of step (6); (8) Based on the calculation results of the quantitative index of the force chain characteristics obtained in step (7), the external load transfer behavior of the asphalt mixture is evaluated.

2. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: In the step (1), when establishing the two-dimensional discrete element model of asphalt mixture, it is assumed that the aggregate particles of the asphalt mixture are round.

3. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: The normal contact force threshold in step (2) is the average value of the normal contact force between aggregates in the two-dimensional discrete element model of asphalt mixture.

4. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: The force chain formation standard in step (3) includes: (31) One force chain is searched at a time, and the starting aggregate of the force chain is determined according to the order of the aggregate y coordinates from large to small; (32) The next level of aggregates is the aggregate that is in contact with the current aggregate in this force chain and whose height is less than or equal to the height of the current aggregate; (33) The angle between two adjacent normal contacts forming a force chain is less than or equal to θ, where θ is the angle value; (34) The number of aggregate particles in the force chain is greater than or equal to N, where N is a positive integer.

5. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: In the step (4), the search process of launching the force chain search according to the force chain formation standard includes: (41) Traverse the MAM set, select the aggregate with the largest y-axis coordinate value as the starting aggregate, increase the number of aggregate particles by 1, and delete the starting aggregate from the MAM set; (42) Determine whether there are aggregates in the set MAAM that are in contact with the starting aggregates. If so, establish an aggregate set MBM for all aggregates that are in contact with the starting aggregates. If not, go to step (41). (43) Traverse the set MBM, determine the aggregate at this level, and increase the number of aggregate particles by 1; (44) If, in the set MAAM, no other aggregates are found in contact with the aggregates of this level except the starting aggregate, then go to step (45); if there are other aggregates in contact with the aggregates of this level, then calculate the angle between the two adjacent normal contacts of the starting aggregate, the aggregates of this level, and each corresponding aggregate of the next level in contact, and go to step (46); (45) Determine whether the number of aggregate particles on the force chain is greater than or equal to N. If the requirement is met, save the force chain information to the force chain array FCMA; if not, there is no need to save, and further determine whether the set MBM has been traversed. If the traversal is completed, go to step (48); if the traversal is not completed, go to step (43); (46) If all the calculated normal contact angles are greater than θ, go to step (47); if there is a normal contact angle less than or equal to θ, the aggregate corresponding to the minimum angle is used as the next level aggregate, and the number of aggregate particles is increased by 1; and the aggregate of this level is defined as the new starting aggregate, and the aggregate of the next level is defined as the new aggregate of this level, and go to step (44); (47) Determine whether the number of aggregate particles on the force chain is greater than or equal to N. If the requirement is met, save the force chain information to the force chain array FCMA; if not, no need to save; and further determine whether the set MBM has been traversed, then go to step (48), otherwise go to step (43); (48) Determine whether the aggregates in the set MAM have been traversed. If not, go to step (41); if traversed, end the search for all force chains.

6. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: In step (5), the repeated force chain structure is defined as the existence of two force chain structures. If the shorter force chain is completely consistent with a continuous part of another force chain, the two force chains are considered to be repeated force chains, and the shorter force chain should be deleted.

7. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: In step (5), the specific process of repeating the force chain search includes: (A) All force chains searched in step (4) are recorded as force chain array FCMA. At the same time, the force chain array FCMA is copied to the force chain array FCMB. At the same time, the duplicate force chains to be deleted are stored in the force chain array YSC. (B) Traverse the force chain array FCMA and determine the analysis object, which is recorded as this force chain; (C) Determine whether this force chain belongs to the force chain array YSC. If so, go to step (B); otherwise, go to step (D); (D) traverse the force chain array FCMB and determine the comparison object, which is recorded as the comparison force chain; (E) Determine whether the position number of the current force chain in the array FCMA is the same as the position number of the comparison force chain in the array FCMB. If they are the same, proceed to step (J); if they are not the same, proceed to step (F); (F) Determine whether the comparison force chain belongs to the force chain array YSC. If not, go to step (G); if yes, compare the length relationship between the current force chain and the comparison force chain. If the length of the comparison force chain is longer than that of the current force chain, go to step (G); otherwise, go to step (J); (G) judging and comparing the force chain and the current force chain, if the shorter force chain is completely consistent with a certain continuous part of the other force chain, proceeding to step (H); otherwise, proceeding to step (J); (H) If the force chain is marked as a repeated force chain, the information of the force chain is saved into the force chain array YSC, and the process goes to step (I); if the comparison force chain is marked as a repeated force chain, the information of the comparison force chain is saved into the force chain array YSC, and the process goes to step (J); (I) Determine whether the force chain array FCMA has been traversed completely. If not, go to step (B); if traversal is completed, end the search; (J) Determine whether the force chain array FCMB has been traversed. If the force chain array FCMB has been traversed, determine whether the force chain array FCMA has been traversed. If the force chain array FCMA has not been traversed, go to step (B); if the force chain array FCMA has been traversed, end the search; if the force chain array FCMB has not been traversed, go to step (D).

8. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: In step (6), the defined quantitative indicators of force chain characteristics include force chain length and force chain direction angle; the length of a single force chain is defined as the sum of all aggregate particle sizes on the single force chain; the force chain direction angle is defined as the angle between the vector formed by the centroids of the starting and ending aggregates on the single force chain as the starting and ending coordinates and the horizontal x-axis direction.

9. The method for evaluating load transfer behavior of asphalt mixture based on quantification of force chain characteristics according to claim 1 is characterized in that: The step (7) specifically comprises: Firstly, the number of force chains of asphalt mixture, the length of each force chain and the direction angle are obtained; then two types of indexes, force chain length distribution and force chain shape distribution, are given and the index values ​​are calculated; The force chain length distribution index includes the total length of the force chain L sum , average force chain length L avg And the proportion of force chains whose length is less than or equal to the height of the virtual specimen P l≤h , and the calculation formulas are as follows: in: N: The total number of force chains generated inside the asphalt mixture under load; l i : The length of the i-th force chain in asphalt mixture, in m; L sum : Total length of the force chain of asphalt mixture, in m; N l≤h : The total number of force chains whose length is less than or equal to the height of the virtual specimen; P l≤h : The proportion of force chains whose length is less than or equal to the height of the virtual specimen; The force chain morphology distribution index includes the average collimation coefficient of the force chain and the average direction angle of the force chain, and the calculation formulas thereof are as follows: in: α p : The angle between the pth adjacent normal contacts on the ith force chain; M: total number of adjacent contacts; δ i : the collimation coefficient value of the i-th force chain; δ avg : The average collimation coefficient of the asphalt mixture force chain; Coordinate (x A ,y A ) and (x B ,y B ) are the position coordinates of aggregates A and B respectively; θ i : The direction angle of the i-th force chain, between 0 and 180°; θ avg : Average direction angle of force chain of asphalt mixture.

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