CN108829939A - A kind of theory and method for numerical simulation for examining the skeleton stability that gathers materials - Google Patents
A kind of theory and method for numerical simulation for examining the skeleton stability that gathers materials Download PDFInfo
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Abstract
The invention discloses a kind of theories and method for numerical simulation for examining the skeleton stability that gathers materials, including：Determine material composition, the local theory's method of inspection, global theory testing method of asphalt；Skeleton sieve pore range of gathering materials is determined according to theory testing；Determine that each shelves gather materials the volume fraction in asphalt；It determines the dispensing number that each shelves gather materials, partial size regulation coefficient, constructs the discrete element simulation model of aggregate mix；Define the rill evolution to gather materials；Determine virtual load mode；Determine virtual load stop condition；Export Simulation results；It determines the key sieve for constituting the skeleton that gathers materials, has determined the key sieve of stabilization, determined the key sieve of interference effect.The present invention realizes the determination of the sieve pore range for playing skeleton function by part and global theory testing method, by the discrete element l-G simulation test of aggregate mix, realizes the method for examining and gathering materials skeleton stability and searching interference partial size.
Description
Technical Field
The invention relates to a theoretical test of aggregate skeleton stability and an aggregate mixture discrete element simulation technology, in particular to a theoretical and numerical simulation method for testing aggregate skeleton stability, which is an aggregate mixture skeleton stability test method based on a three-dimensional discrete unit method and belongs to the technical field of road engineering. .
Background
To test the framework stability of the aggregate mixture in the asphalt mixture, firstly, the material composition and the material properties of the asphalt mixture need to be obtained, and a local and global theoretical test method is established under the conditions of known aggregate gradation, asphalt content, void ratio, effective asphalt content, asphalt content absorbed by the aggregate, asphalt density and aggregate density. If the conditions are known, the adding number of each grade of aggregate can be calculated according to the material composition, and an aggregate mixture virtual test piece is established to carry out a three-dimensional aggregate mixture compression test.
It is required to know that the stability of aggregate gradation cannot be visually checked in indoor tests and field tests, the contribution rate of aggregates with different meshes to an aggregate framework cannot be known, and the stability of the aggregate framework can be indirectly evaluated only through the macroscopic performance of the asphalt mixture at various temperatures, so that time consumption and cost are increased, and the evaluation result obtained by the tests is not ideal.
However, the stability of the aggregate framework can be visually checked through the aggregate mixture virtual compression test, and the contribution rate of aggregates with different particle sizes to the aggregate framework can be counted.
Disclosure of Invention
The invention aims to provide a theoretical and numerical simulation method for testing aggregate skeleton stability, the method is a theoretical and numerical simulation test method under the conditions of known aggregate gradation, asphalt content, void ratio, effective asphalt content, asphalt content absorbed by the aggregate, asphalt density, asphalt mixture density and aggregate density, the sieve pore range forming the aggregate framework can be obtained according to the local and global theoretical inspection methods, the interference effect of substances outside the aggregate framework range on the framework is determined, according to the aggregate mixture compression test, the key sieve pores forming the aggregate framework under the gradation, the key sieve pores playing a stabilizing role and the key sieve pores playing an interfering role can be quickly and accurately obtained, the problems of high cost, time consumption, non-visual test results and volatility of the current indoor test and field test are solved.
The invention adopts the following technical scheme for solving the technical problems:
the invention provides a theoretical and numerical simulation method for testing aggregate skeleton stability, which comprises the following steps:
(1) determining the material composition of the asphalt mixture: firstly, determining the material composition and the material property of the asphalt mixture, and then determining basic parameters required by calculation of inspection parameters according to the material property;
(2) determining a local theoretical inspection method: defining a local theoretical inspection method according to the state of contact between particles of adjacent sieve pores, and defining local inspection parameters;
(3) determining a global theoretical inspection method: defining a global theoretical inspection method according to the interference degree of substances outside the range of forming the aggregate framework on the aggregate framework, and defining global inspection parameters;
(4) determining the sieve pore range of the aggregate framework according to theoretical inspection: determining the sieve pore range of the aggregate framework according to the local and global theoretical inspection methods and the inspection parameters, and determining the interference effect of substances outside the aggregate framework range on the framework;
(5) determining the feeding number of each grade of aggregate: determining the volume fraction of the aggregate mixture in the asphalt mixture according to the material composition and the material property of the asphalt mixture, and determining the volume fraction of each grade of aggregate in the asphalt mixture by combining the passing rate of each grade of aggregate; determining the feeding number of each grade of aggregate according to the volume fraction of each grade of aggregate in the asphalt mixture, the volume fraction of the aggregate mixture in the asphalt mixture and the average particle size of each grade of aggregate;
(6) constructing a discrete element simulation model of the aggregate mixture: determining the size and loading rate of a virtual test piece, establishing a fixed boundary condition, determining the particle size adjustment coefficient of each grade of aggregate, determining the mesoscopic parameters of the aggregate, and establishing an aggregate mixture discrete element simulation model;
(7) determining a virtual loading mode: determining three states of a virtual loading mode according to the state of the aggregate mixture after the aggregate mixture is put, wherein the three states are natural stacking, preloading and formal loading in sequence;
(8) determining a virtual load stop condition: determining the maximum load of the aggregate which starts to be damaged as a first virtual loading stop condition according to a crushing value test of the aggregate mixture, and taking the maximum strain reaching 0.2 as a second virtual loading stop condition to prevent the structural reorganization of the aggregate mixture;
(9) outputting a simulation test result: outputting a simulation test result after the virtual loading is stopped, wherein the simulation test result comprises a virtual loading plate force-displacement curve, a contact force of each contact position of each grade of aggregate, the contact quantity of each grade of aggregate and the throwing number of each grade of aggregate;
(10) determining the key sieve pores constituting the aggregate skeleton: defining the contact force of at least one contact point of the particles playing the role of the aggregate skeleton to be larger than the average contact force of the aggregate mixture, defining the contact point playing the role of the skeleton in each grade of aggregate to be the contact force of the contact position in each grade of aggregate to be larger than the average contact force, and defining the contribution of each grade of aggregate to the aggregate skeleton to be the sum of the contact forces of the contact points playing the role of the skeleton of each grade of aggregate divided by the sum of the contact forces of the contact points playing the role of the skeleton of all grades of aggregate; counting the contribution of each grade of aggregate to the aggregate skeleton according to the simulation result output in the step (9), drawing a curve graph of the aggregate sieve holes and the contribution of the aggregates of the corresponding sieve holes to the aggregate skeleton, and defining that if the sum of the contributions of any two grades of aggregates at the wave crest to the aggregate skeleton exceeds 50%, the key sieve holes forming the aggregate skeleton are defined;
(11) determination of the critical mesh for stabilization: defining the contact force of the contact points of the particles playing a role in stabilizing the skeleton to be smaller than the average contact force of the aggregate mixture, defining the contact point playing a role in stabilizing in each grade of aggregate to be the contact force at the contact position in each grade of aggregate to be smaller than the average contact force, defining the contribution of each grade of aggregate to stabilizing the aggregate skeleton to be the sum of the contact forces of the contact points playing a role in stabilizing each grade of aggregate, and dividing the sum of the contact forces of the contact points playing a role in stabilizing all the grades of aggregate; counting the contribution of each grade of aggregate to a stable aggregate framework, drawing a graph of aggregate sieve holes and the contribution of aggregates with corresponding sieve holes to the stable aggregate framework, and defining the key sieve holes with the stabilizing effect if the sum of the contributions of any two grades of aggregates at the wave crest to the stable aggregate framework exceeds 50%;
(12) determination of the critical sieve openings that play a role in interference: and (4) according to the curve graph of the contribution of the aggregate sieve pores drawn in the step (11) and aggregates of the corresponding sieve pores to the stable aggregate framework, defining the sieve pore grain sizes corresponding to the positions with abnormal bulges adjacent to the wave crests as the key sieve pores playing a role in interference.
As a further technical solution of the present invention, in the step (1), the determining the material composition and the material property of the asphalt mixture specifically includes: total content of asphalt WbContent of effective asphaltAsphalt content absorbed by aggregateVoid fraction VvDensity of bitumen ρbApparent density of asphalt mixture ρmDensity of aggregate ρaVolume V of asphalt mixture test pieceTAnd the passing rate P of the ith grade aggregatea(i) Wherein, the i-1 st grade grain size is the maximum first grade aggregate grain size, and the aggregate grain size decreases with the increase of i;
the determination of the basic parameters required for the calculation of the inspection parameters from the material properties specifically comprises: volume fraction of ith grade aggregateAverage particle size of i-th grade aggregateVolume of asphalt absorbed by aggregateVolume of available asphaltTotal volume V of aggregate mixtureatAnd the volume fraction of the aggregate mixture in the bituminous mixture test pieceNumber ofWherein, Di-1is the particle size of the sieve mesh of the i-1 st gear, DiThe particle size of the sieve mesh of the i-th grade.
As a further technical solution of the present invention, in the step (2), the method for determining the local theoretical inspection specifically comprises: the sieve pores which form the aggregate framework are in a state that the particles between adjacent sieve pores are required to be kept in contact, the limit state of the sieve pores is divided into a close contact state and a loose contact state, the close contact is defined as the condition that the aggregate particles with larger sieve pores in two adjacent grades of aggregates are kept in mutual contact, the aggregate particles with smaller sieve pores in the two adjacent grades of aggregates are filled in the gaps of the aggregate with larger sieve pores, and the loose contact is defined as the condition that the aggregate particles with larger sieve pores in the two adjacent grades of aggregates are kept in mutual contact with the aggregate particles with smaller sieve pores in the two adjacent grades of aggregates;
the local theoretical inspection parameters of the i-th grade aggregate comprise the weighted average grain diameter of the i-th grade aggregate and the i + 1-th grade aggregateAnd the volume fraction of the ith grade aggregate in the ith grade and the (i + 1) th grade aggregatesWherein,
if the local theoretical inspection parameters of the ith grade aggregate meet the local theoretical inspection formulaAndnamely, the aggregate of the grade meets the local theoretical inspection; and (4) sequentially inspecting the aggregates from the first grade to the last grade according to a local theoretical inspection formula, thereby determining the sieve pore range of the aggregate framework.
As a further technical solution of the present invention, in the step (3), the determining of the global theoretical inspection method specifically includes: the global theoretical test method is defined as that the gap formed by the aggregate skeleton can be filled with medium components without interference, and the expression isThe interference factor is defined as the interference degree D of the medium components on the aggregate skeletonFWherein the volume of the void formed by the aggregate in the sieve pore range constituting the aggregate skeleton obtained in the step (2), Va SSIs less than the aggregate total volume of the smallest sieve pore of the aggregate skeleton,is the volume of asphalt absorbed that is less than the fine aggregate making up the smallest mesh opening of the aggregate skeleton.
As a further technical proposal of the invention, in the step (5), the throwing number of the i-th grade aggregateWherein the volume fraction of the i-th grade aggregate in the asphalt mixture
As a further technical solution of the present invention, in the step (6), the constructing of the discrete element simulation model of the aggregate mixture specifically includes: determining the size and loading rate of a virtual test piece according to an asphalt mixture compression test in a road engineering asphalt and asphalt mixture test procedure, establishing a fixed boundary condition, putting each grade of aggregate in the virtual test piece in a random distribution mode according to the putting number of each grade of aggregate calculated in the step (5), defining mesoscopic parameters of the aggregate according to the macroscopic property of the aggregate and a conversion formula of mesoscopic and macroscopic, and determining an ith grade particle size adjustment coefficient A according to the fact that the put volume is equal to the actual volumef(i) The particle size of each grade of aggregate is scaled by adopting a particle size adjusting coefficient, and an aggregate mixture discrete element simulation model is established; wherein A isf(i) Is calculated by the formulaVk(i) Is the volume of the kth aggregate in the ith grade of aggregate.
As a further technical scheme of the invention, in the step (10), the contribution of the ith grade aggregate to the aggregate skeletonWherein the average contact force of the entire aggregate mixtureFijThe contact force at the jth contact point in the ith grade aggregate is m, and the total grade number of the sieve holes is m.
As a further technical scheme of the invention, in the step (11), the contribution of the ith grade aggregate to the stable aggregate skeletonWherein the average contact force of the entire aggregate mixtureFijFor the jth contact point in the ith grade aggregateM is the total number of sieve holes.
As a further technical scheme of the invention, in the steps (10) and (11), a graph of the abscissa of the aggregate sieve pore and the contribution of the aggregate in the corresponding sieve pore to the aggregate skeleton is drawn.
Compared with the prior art, the invention adopting the technical scheme has the following technical effects: according to the method for testing the local and global theories of the stability of the aggregate framework, provided by the invention, the sieve pore range of the aggregate framework formed by multiple gradations can be determined by defining the local and global theories and testing parameters, and the interference effect of substances outside the range of the aggregate framework on the framework is determined; through the virtual compression test of the aggregate mixture, the stability of the aggregate mixture framework under the states of various gradations, various asphalt using amounts and various medium void ratios can be simulated, the key sieve pores forming the aggregate framework, the key sieve pores playing a stabilizing role and the key sieve pores playing an interfering role can be visually determined, and the contribution rate of each grade of aggregate to the stability of the aggregate framework can be known.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings:
as shown in fig. 1, a theoretical and numerical simulation method for testing aggregate skeleton stability includes the following steps:
determining the material composition and material properties of the asphalt mixture: including total content of asphalt (W)b) Content of effective asphaltAsphalt content absorbed by aggregateVoid ratio (V)v) Density of bitumen (. rho.)b) Apparent density of asphalt mixture (p)m) Density of aggregate (ρ)a) Volume of asphalt specimen (V)T) And the passing rate (P) of the ith grade aggregatea(i) And the i-1 st grade grain size is the maximum first grade aggregate grain size, and the aggregate grain size is reduced along with the increase of i.
The determination of the basic parameters required for the calculation of the inspection parameters from the material properties specifically comprises: volume fraction of ith grade aggregateAverage particle size of i-th grade aggregateVolume of asphalt absorbed by aggregateVolume of available asphaltTotal volume of aggregate mixture (V)at) The volume fraction of the aggregate mixture in the asphalt mixture test pieceThe calculation formula is as follows:
in the formula, Di-1Is the particle size of the sieve mesh of the i-1 st gear, DiThe particle size of the sieve mesh of the i-th grade.
(II) determining a local theoretical inspection method:
the sieve pores which are consistent with the sieve pores forming the aggregate framework are required to meet the condition that particles between adjacent sieve pores are required to be kept in contact, the limit state of the sieve pores is divided into a close contact state and a loose contact state, the close contact state is defined as that the particles of the aggregate with the larger sieve pores in two adjacent grades of aggregates are kept in mutual contact, the particles of the aggregate with the smaller sieve pores in the two adjacent grades of aggregates are filled in the gaps of the aggregate with the larger sieve pores, and the loose contact state is defined as that the particles of the aggregate with the larger sieve pores in the two adjacent grades of aggregates are kept in mutual contact with the particles of.
The local theoretical inspection parameters of the i-th grade aggregate comprise the weighted average grain diameter of the i-th grade aggregate and the i + 1-th grade aggregateAnd the volume fraction of the ith grade aggregate in the ith grade and the (i + 1) th grade aggregatesThe calculation formulas are respectively formula (7) and (8):
if the local theoretical inspection parameters of the ith grade aggregate are satisfied between the close contact state and the loose contact state (including the close contact state and the loose contact state), namely, the grade aggregate satisfies the local theoretical inspection, the inspection formulas are expressed as formulas (9) and (10):
and sequentially inspecting the first gear to the last gear according to a local theoretical inspection formula to determine the sieve pore range capable of forming the aggregate framework.
(III) determining a global theoretical inspection method:
obtaining the sieve pore range capable of forming aggregate skeleton according to local theoretical inspection method, and calculating the volume of the void formed by aggregate in the sieve pore rangeCalculating aggregate total volume V smaller than minimum sieve pore of aggregate skeletona SSAnd the volume of pitch absorbed
The global theoretical test method is defined as that the gap formed by the aggregate main skeleton can be filled with medium components without interference, and the expression is shown in formula (11); the interference factor is defined as the interference degree (D) of the medium components on the aggregate skeletonF) The calculation formula is shown in formula (12).
And (IV) determining the sieve pore range of the aggregate framework according to theoretical inspection: determining the sieve pore range of the aggregate framework according to the local and global theoretical detection methods and detection parameters, and determining the interference effect of substances outside the aggregate framework range on the framework.
(V) determining the feeding number of each grade of aggregate: according to volume fraction of i-th grade aggregateThe volume fraction of the mixture of the aggregate and the asphalt mixtureCalculating the volume fraction of the i-th aggregate in the asphalt mixtureThe calculation formula is formula (13); then according to the volume fraction of the i-th grade aggregate in the asphalt mixtureAverage particle size of i-th grade aggregateAnd volume (V) of specimen of asphalt mixtureT) Determining the number of i-th grade aggregate (N)i) The calculation formula is formula (14).
(VI) constructing a discrete element simulation model of the aggregate mixture: determining the size and loading rate of a virtual test piece according to a uniaxial compression test of asphalt mixture in a JTG E20-2011 highway engineering asphalt and asphalt mixture test procedure, randomly putting the number of each grade of aggregate obtained by the previous step in the virtual test piece as the aggregate is an unbonded discrete mixture during loading, defining the mesoscopic parameters of the aggregate according to the macroscopic property of the aggregate and a conversion formula of mesoscopic and macroscopic, and determining the particle size adjustment coefficient of the ith grade (A) according to the fact that the put volume is equal to the actual volumef(i) And (15) scaling the grain diameter of each grade of aggregate by using the grain diameter adjusting coefficient to establish an aggregate mixture discrete element simulation model closer to the actual state.
(VII) determining a virtual loading mode: and determining three states of a virtual loading mode, namely natural stacking, preloading and formal loading in sequence according to the state of the aggregate mixture after the aggregate mixture is put.
(eight) determining a virtual load stop condition: the maximum load at which the aggregate begins to fail is determined as a first virtual load stop condition based on a crush value test of the aggregate mixture, and a maximum strain of 0.2 is required as a second virtual load stop condition to prevent structural reorganization of the aggregate mixture.
(nine) outputting a simulation test result: and after the virtual loading is stopped, outputting a simulation test result which comprises a virtual loading plate force-displacement curve, a contact force of each contact position of each grade of aggregate, the contact quantity of each grade of aggregate and the throwing quantity of each grade of aggregate.
(ten) determining the key sieve pores forming the aggregate skeleton:
extracting contact force of ith grade aggregateAnd the number of ith aggregate (N)i) Calculating the average contact force (F) of the entire aggregate mixturetavg) The calculation formula is (16).
Defining the contact force of at least one contact point of the particles playing the role of aggregate skeleton to be larger than the average contact force of the aggregate mixture, defining the contact point playing the role of skeleton in the ith grade of aggregate as the contact force of the contact position in the ith grade of aggregate to be larger than the average contact force, defining the contribution f of the ith grade of aggregate to the aggregate skeletonti＞tavgThe sum of the contact forces of the contact points which act as the skeleton for each grade of aggregate divided by the sum of the contact forces of the contact points which act as the skeleton for all grades of aggregate is calculated as (17).
And (7) counting the contribution of each grade of aggregate to the aggregate skeleton according to the simulation result output in the step (nine), drawing a curve graph of aggregate sieve holes (abscissa) and the contribution of the aggregate of the corresponding sieve holes to the aggregate skeleton, and defining that if the sum of the contributions of any two grades of aggregates at the wave crest to the aggregate skeleton exceeds 50%, the key sieve holes forming the aggregate skeleton are defined.
In the formula, FijThe contact force at the jth contact point in the ith grade aggregate is m, and the total grade number is m.
(eleven) determination of the critical mesh for stabilization:
defining the contact force of the contact point of the particles which play a role of stabilizing the skeleton to be less than the average contact force of the aggregate mixture, defining the contact point which plays a role of stabilizing in the ith grade of aggregate to be the contact point of the contact position in the ith grade of aggregate to be less than the average contact force, and defining the ith gradeContribution f of grade aggregate to stable aggregate frameworkti≤tavgThe sum of the contact forces of the contact points with the stabilization function for the ith grade aggregate is divided by the sum of the contact forces of the contact points with the stabilization function for all the grade aggregates, and the calculation formula is the formula (18).
And (7) counting the contribution of each grade of aggregate to the stable aggregate skeleton according to the simulation result output in the step (nine), drawing a curve graph of aggregate sieve holes (abscissa) and the contribution of the aggregate with the corresponding sieve holes to the stable aggregate skeleton, and defining the key sieve holes with the stabilizing effect if the sum of the contributions of any two grades of aggregates at the wave crest to the stable aggregate skeleton exceeds 50%.
(twelve) determination of the critical mesh that plays a role in interference:
and (5) according to the curve graph of the aggregate sieve pores (abscissa) drawn in the step (eleven) and the contribution of aggregates of the corresponding sieve pores to the stable aggregate skeleton, defining the sieve pore grain size corresponding to the position with abnormal bulges adjacent to the wave crest as the key sieve pore playing the role of interference.
The invention relates to a theory and numerical simulation method for testing aggregate skeleton stability, which realizes the determination of the sieve pore range playing the skeleton function through a local and global theory test method, and realizes the methods for testing the aggregate skeleton stability and searching for interference particle size through a discrete element simulation test of an aggregate mixture. The theoretical inspection method and the simulation program inspection algorithm have strong reproducibility and intelligence, do not limit the type of inspection gradation, and provide reference for the optimization design of aggregate gradation and asphalt mixture.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can understand that the modifications or substitutions within the technical scope of the present invention are included in the scope of the present invention, and therefore, the scope of the present invention should be subject to the protection scope of the claims.
Claims (9)
1. A theory and numerical simulation method for testing aggregate skeleton stability is characterized by comprising the following steps:
(1) determining the material composition of the asphalt mixture: firstly, determining the material composition and the material property of the asphalt mixture, and then determining basic parameters required by calculation of inspection parameters according to the material property;
(2) determining a local theoretical inspection method: defining a local theoretical inspection method according to the state of contact between particles of adjacent sieve pores, and defining local inspection parameters;
(3) determining a global theoretical inspection method: defining a global theoretical inspection method according to the interference degree of substances outside the range of forming the aggregate framework on the aggregate framework, and defining global inspection parameters;
(4) determining the sieve pore range of the aggregate framework according to theoretical inspection: determining the sieve pore range of the aggregate framework according to the local and global theoretical inspection methods and the inspection parameters, and determining the interference effect of substances outside the aggregate framework range on the framework;
(5) determining the feeding number of each grade of aggregate: determining the volume fraction of the aggregate mixture in the asphalt mixture according to the material composition and the material property of the asphalt mixture, and determining the volume fraction of each grade of aggregate in the asphalt mixture by combining the passing rate of each grade of aggregate; determining the feeding number of each grade of aggregate according to the volume fraction of each grade of aggregate in the asphalt mixture, the volume fraction of the aggregate mixture in the asphalt mixture and the average particle size of each grade of aggregate;
(6) constructing a discrete element simulation model of the aggregate mixture: determining the size and loading rate of a virtual test piece, establishing a fixed boundary condition, determining the particle size adjustment coefficient of each grade of aggregate, determining the mesoscopic parameters of the aggregate, and establishing an aggregate mixture discrete element simulation model;
(7) determining a virtual loading mode: determining three states of a virtual loading mode according to the state of the aggregate mixture after the aggregate mixture is put, wherein the three states are natural stacking, preloading and formal loading in sequence;
(8) determining a virtual load stop condition: determining the maximum load of the aggregate which starts to be damaged as a first virtual loading stop condition according to a crushing value test of the aggregate mixture, and taking the maximum strain reaching 0.2 as a second virtual loading stop condition to prevent the structural reorganization of the aggregate mixture;
(9) outputting a simulation test result: outputting a simulation test result after the virtual loading is stopped, wherein the simulation test result comprises a virtual loading plate force-displacement curve, a contact force of each contact position of each grade of aggregate, the contact quantity of each grade of aggregate and the throwing number of each grade of aggregate;
(10) determining the key sieve pores constituting the aggregate skeleton: defining the contact force of at least one contact point of the particles playing the role of the aggregate skeleton to be larger than the average contact force of the aggregate mixture, defining the contact point playing the role of the skeleton in each grade of aggregate to be the contact force of the contact position in each grade of aggregate to be larger than the average contact force, and defining the contribution of each grade of aggregate to the aggregate skeleton to be the sum of the contact forces of the contact points playing the role of the skeleton of each grade of aggregate divided by the sum of the contact forces of the contact points playing the role of the skeleton of all grades of aggregate; counting the contribution of each grade of aggregate to the aggregate skeleton according to the simulation result output in the step (9), drawing a curve graph of the aggregate sieve holes and the contribution of the aggregates of the corresponding sieve holes to the aggregate skeleton, and defining that if the sum of the contributions of any two grades of aggregates at the wave crest to the aggregate skeleton exceeds 50%, the key sieve holes forming the aggregate skeleton are defined;
(11) determination of the critical mesh for stabilization: defining the contact force of the contact points of the particles playing a role in stabilizing the skeleton to be smaller than the average contact force of the aggregate mixture, defining the contact point playing a role in stabilizing in each grade of aggregate to be the contact force at the contact position in each grade of aggregate to be smaller than the average contact force, defining the contribution of each grade of aggregate to stabilizing the aggregate skeleton to be the sum of the contact forces of the contact points playing a role in stabilizing each grade of aggregate, and dividing the sum of the contact forces of the contact points playing a role in stabilizing all the grades of aggregate; counting the contribution of each grade of aggregate to a stable aggregate framework, drawing a graph of aggregate sieve holes and the contribution of aggregates with corresponding sieve holes to the stable aggregate framework, and defining the key sieve holes with the stabilizing effect if the sum of the contributions of any two grades of aggregates at the wave crest to the stable aggregate framework exceeds 50%;
(12) determination of the critical sieve openings that play a role in interference: and (4) according to the curve graph of the contribution of the aggregate sieve pores drawn in the step (11) and aggregates of the corresponding sieve pores to the stable aggregate framework, defining the sieve pore grain sizes corresponding to the positions with abnormal bulges adjacent to the wave crests as the key sieve pores playing a role in interference.
2. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 1, wherein in the step (1), the determining the material composition and the material properties of the asphalt mixture specifically comprises: total content of asphalt WbIs provided withContent of effective asphaltAsphalt content absorbed by aggregateVoid fraction VvDensity of bitumen ρbApparent density of asphalt mixture ρmDensity of aggregate ρaVolume V of asphalt mixture test pieceTAnd the passing rate P of the ith grade aggregatea(i) Wherein, the i-1 st grade grain size is the maximum first grade aggregate grain size, and the aggregate grain size decreases with the increase of i;
the determination of the basic parameters required for the calculation of the inspection parameters from the material properties specifically comprises: volume fraction of ith grade aggregateAverage particle size of i-th grade aggregateVolume of asphalt absorbed by aggregateVolume of available asphaltTotal volume V of aggregate mixtureatAnd the volume fraction of the aggregate mixture in the asphalt mixture test pieceWherein,
Di-1for the i-1 th screenParticle size of pores, DiThe particle size of the sieve mesh of the i-th grade.
3. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 2, wherein in the step (2), the method for determining the local theoretical test specifically comprises the following steps: the sieve pores which form the aggregate framework are in a state that the particles between adjacent sieve pores are required to be kept in contact, the limit state of the sieve pores is divided into a close contact state and a loose contact state, the close contact is defined as the condition that the aggregate particles with larger sieve pores in two adjacent grades of aggregates are kept in mutual contact, the aggregate particles with smaller sieve pores in the two adjacent grades of aggregates are filled in the gaps of the aggregate with larger sieve pores, and the loose contact is defined as the condition that the aggregate particles with larger sieve pores in the two adjacent grades of aggregates are kept in mutual contact with the aggregate particles with smaller sieve pores in the two adjacent grades of aggregates;
the local theoretical inspection parameters of the i-th grade aggregate comprise the weighted average grain diameter of the i-th grade aggregate and the i + 1-th grade aggregateAnd the volume fraction of the ith grade aggregate in the ith grade and the (i + 1) th grade aggregatesWherein,
if the local theoretical inspection parameters of the ith grade aggregate meet the local theoretical inspection formulaAndnamely, the aggregate of the grade meets the local theoretical inspection; according to local theoryThe first grade to the last grade of aggregate are sequentially inspected by an inspection formula, so that the sieve pore range of the aggregate framework is determined.
4. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 3, wherein in the step (3), the method for determining the global theoretical test is specifically as follows: the global theoretical test method is defined as that the gap formed by the aggregate skeleton can be filled with medium components without interference, and the expression isThe interference factor is defined as the interference degree D of the medium components on the aggregate skeletonFWherein the volume of the void formed by the aggregate in the sieve pore range constituting the aggregate skeleton obtained in the step (2), Va SSIs less than the aggregate total volume of the smallest sieve pore of the aggregate skeleton,is the volume of asphalt absorbed that is less than the fine aggregate making up the smallest mesh opening of the aggregate skeleton.
5. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 4, wherein in the step (5), the number of i-th grade aggregates to be put is determinedWherein the volume fraction of the i-th grade aggregate in the asphalt mixture
6. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 5, wherein in the step (6), the construction of the discrete element simulation model of the aggregate mixture comprises: determining the size and loading rate of a virtual test piece according to an asphalt mixture compression test in a road engineering asphalt and asphalt mixture test procedure, establishing a fixed boundary condition, putting each grade of aggregate in the virtual test piece in a random distribution mode according to the putting number of each grade of aggregate calculated in the step (5), defining mesoscopic parameters of the aggregate according to the macroscopic property of the aggregate and a conversion formula of mesoscopic and macroscopic, and determining an ith grade particle size adjustment coefficient A according to the fact that the put volume is equal to the actual volumef(i) The particle size of each grade of aggregate is scaled by adopting a particle size adjusting coefficient, and an aggregate mixture discrete element simulation model is established; wherein A isf(i) Is calculated by the formulaVk(i) Is the volume of the kth aggregate in the ith grade of aggregate.
7. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 6, wherein in the step (10), the contribution of the ith grade aggregate to the aggregate skeletonWherein the average contact force of the entire aggregate mixtureFijThe contact force at the jth contact point in the ith grade aggregate is m, and the total grade number is m.
8. The theoretical and numerical simulation method for testing aggregate skeleton stability according to claim 6, wherein, in the step (11),contribution of ith grade aggregate to stable aggregate skeletonWherein the average contact force of the entire aggregate mixtureFijThe contact force at the jth contact point in the ith grade aggregate is m, and the total grade number is m.
9. A theoretical and numerical simulation method for testing aggregate skeletal stability according to claim 1, characterized in that, in steps (10) and (11), the abscissa of the aggregate mesh and the contribution of the aggregate in the corresponding mesh to the aggregate skeleton are plotted.
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