A method for establishing a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water and its application

Abstract

This invention proposes a method for establishing and applying a multiscale model of asphalt pavement damage that considers the combined effects of dynamic and static water. The multiscale model establishment method includes: determining a comprehensive damage factor for the combined effects of dynamic and static water through experimental analysis of the water damage characteristics of asphalt mortar and asphalt mixture; establishing a micromechanical model, including a viscoelastic constitutive model for water damage to asphalt mortar, a model for the evolution of static water damage, and a cohesive force model describing adhesion and cohesive damage; and establishing a macromechanical model, including a viscoelastic constitutive model for water damage to asphalt mixture, a model for the evolution of static water damage, and a model for the evolution of dynamic water damage. Finite element analysis is used to establish the RVE model and macromodel of the asphalt pavement, respectively. The viscoelastic constitutive model is incorporated into the UMAT subroutine, and numerical calculations are performed for the macro- and micro-scale water damage model for the combined effects of dynamic and static water. The macro- and micro-scale numerical models are then connected using a homogenization method to achieve water damage prediction from microscopic properties to macroscopic performance.

Description

Technical Field

[0001] The invention belongs to the field of road engineering mechanics models. Background Art

[0002] Water is the main factor causing various early damages to asphalt pavements. When the pavement is in a certain humid or water environment for a long time, moisture continuously invades the interior of the mixture, the physical and chemical properties of the asphalt binder change, the adhesion between the asphalt and the aggregate decreases, and eventually the asphalt peels off from the aggregate surface, leading to a series of pavement diseases such as potholes, subsidence, and cracking, which affect the performance and life of the pavement.

[0003] According to mechanical adhesion theory, water damage to asphalt pavements can be divided into two stages: water diffusion (referred to as static hydrodynamics) and water accumulation and erosion, resulting in dynamic water flow (referred to as dynamic hydrodynamics). When free water is present in an asphalt pavement, water molecules continuously diffuse into the asphalt mixture. As water accumulates, the pores within the asphalt mixture gradually fill with water, connecting the pore channels. The pumping action of vehicle loads generates hydrodynamic pressure, which erodes the asphalt-aggregate bond, causing cracking of the binder film and entry of water into the binder-aggregate interface. The resulting mechanical abrasion accelerates asphalt spalling. The water diffusion stage is a long-term, chronic damage process, as the entry of water molecules into the asphalt mixture involves molecular motion and takes a long time. In contrast, the accumulation and dynamic flow of water are macroscopic physical processes that depend on factors such as mixture type, traffic load, and environmental conditions. Therefore, the second stage is a short-term, localized damage process.

[0004] Water damage to asphalt pavement is the combined result of long-term static water immersion and short-term dynamic water flow scouring and pumping. Long-term static water action and short-term dynamic water action are two different damage mechanisms. Due to the difference in damage mechanisms, existing research on water damage to asphalt pavements often separates dynamic water action from static water action. In terms of testing, test methods representing static water action and dynamic water action have been developed separately. For example, the representative test for static water action is the improved Lottman test; dynamic water action usually uses MIST for water sensitivity testing. In terms of numerical analysis, static water research usually establishes a microscopic model of asphalt mixture based on water diffusion theory, while dynamic water research usually establishes a pavement macroscopic structure model based on Biot consolidation theory and porous media theory. Current research has not combined long-term and short-term water damage effects under dynamic and static water environments. Although these experimental methods and numerical simulation methods can reveal the water damage mechanical behavior of asphalt pavement materials at different scales at the macro, micro and micro scales respectively, the separation between different scales makes it impossible to accurately predict the occurrence of macro water damage of asphalt pavements. In order to more effectively reduce the occurrence of early diseases of asphalt pavements and extend the service life of asphalt pavements, it is necessary to develop a multi-scale model that can connect the microstructural properties of asphalt mixtures with the macro water damage mechanical properties of pavements. Summary of the Invention

[0005] In response to the current situation where the interaction of dynamic and static water on asphalt pavements is insufficiently considered and research methods are limited, the present invention provides a multi-scale model of asphalt pavement damage that takes into account the interaction of dynamic and static water, which is used to address the problem of inaccurate prediction of water damage performance of asphalt pavements in existing technologies. By leveraging the theory of continuum damage mechanics, the theory of micromechanics, and indoor experiments on asphalt materials, the present invention proposes a comprehensive damage factor for the interaction of dynamic and static water on asphalt materials and establishes a macro- and micro-mechanical model of water damage on asphalt pavements. Using simulation software, the present invention establishes a macro- and micro-numerical model of the pavement structure and a micro-numerical model of the asphalt mixture. The macro- and micro-numerical models of the pavement structure and the asphalt mixture are then linked through a homogenization method. Finally, the present invention completes the numerical analysis of the multi-scale model of asphalt pavement damage that takes into account the interaction of dynamic and static water, thereby realizing the prediction of water damage on asphalt pavements.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] One of the technical solutions:

[0008] A method for establishing a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water, wherein the multi-scale model includes a micromechanical model and a macromechanical model, and the establishment method includes the following steps:

[0009] Step 1: Selection of raw materials for asphalt mortar and asphalt mixture and characterization of physical and mechanical properties;

[0010] Step 2: Design of water damage test for asphalt pavement materials;

[0011] Step 3: Experimental analysis of water damage characteristics of asphalt pavement materials;

[0012] Step 4: Determine the static water damage factor based on continuum damage mechanics and water damage characteristics test data of asphalt pavement materials , dynamic water damage factor , comprehensive damage factor of dynamic and static water ;

[0013] Step 5: Establish a micromechanical model, including: based on the Maxwell model and the hydrostatic damage factor , a viscoelastic constitutive model of water damage to asphalt mortar was established; Fick's second law was used to describe the diffusion of water in asphalt mortar, and a model of the hydrostatic damage evolution process at the mesoscopic scale was established; a cohesive force model was used to describe the bonding and cohesive damage;

[0014] Step 6: Establish a macroscopic mechanical model, including: a comprehensive damage factor based on the Maxwell model and the combined action of dynamic and static water , a viscoelastic constitutive model of water damage of asphalt mixture is established; Fick's second law is used to describe the diffusion effect of water in asphalt mixture, and a model of the static water damage evolution process on a macro scale is established; Biot consolidation theory is used to describe the pumping effect of water in asphalt mixture, and a model of the dynamic water damage evolution process on a macro scale is established.

[0015] Technical solution 2:

[0016] An application of a multi-scale model for asphalt pavement damage that considers the combined effects of dynamic and static water. The multi-scale model is established using the above method, and asphalt pavement water damage prediction is achieved based on the multi-scale model.

[0017] Furthermore, asphalt pavement water damage prediction based on the multi-scale model includes the following steps:

[0018] Step S1: The RVE of the asphalt pavement is selected as the mesoscopic numerical model of the asphalt mixture. In the mesoscopic numerical model, the aggregate is defined as an elastic material, the asphalt mortar is defined as a viscoelastic material, and the bonding damage at the interface between the aggregate and the asphalt mortar and the cohesive damage within the asphalt mortar are both characterized using the CZM model;

[0019] At the same time, a macroscopic numerical model of the asphalt pavement structure is established, in which: the top layer is the asphalt mixture surface layer; the second is the semi-rigid cement stabilized gravel base layer; and the bottom layer is the soil base layer;

[0020] Step S2: Based on the mesoscopic numerical model and macroscopic numerical model from step S1, the water damage viscoelastic constitutive model of asphalt mortar and the water damage viscoelastic constitutive model of asphalt mixture are written into the finite element UMAT subroutine respectively to realize the numerical calculation of the macroscopic and microscopic water damage models under the combined action of dynamic and static water.

[0021] Step S3: The fine numerical model and the macro numerical model are linked by a homogenization method to complete the numerical analysis of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water;

[0022] Step S4: Based on the macro-equivalent stress-strain response of the asphalt pavement, the macro-equivalent elastic parameters of the asphalt pavement are calculated to predict the water damage performance of the asphalt pavement.

[0023] The beneficial effects of the present invention are:

[0024] The present invention considers the long-term effects of static water and the short-term effects of dynamic water on asphalt pavements during their service, and proposes a multi-scale model of asphalt pavement damage that considers the combined effects of static and dynamic water. The model is used to predict the water damage performance of asphalt pavements, which makes up for the shortcomings of existing asphalt material water damage test methods that only consider static water or dynamic water damage separately. It has important reference significance for understanding the changes in the mechanical properties of real asphalt pavements under the combined effects of static and dynamic water.

[0025] The present invention establishes a multi-scale model of asphalt pavement damage that takes into account the combined effects of dynamic and static water, introduces water damage into the macro- and micro-mechanical models of asphalt pavements, and strengthens the theoretical basis for the study of water damage to asphalt pavements. Currently, research on the environmental impact of asphalt pavements is mostly considered in the form of external environmental loads, and research on the mechanical theory of materials and structures themselves is relatively weak. The present invention is of great help in developing more accurate mechanical models.

[0026] The present invention uses the UMAT subroutine to encapsulate the water damage viscoelastic constitutive model of the macro-micro mechanical model of water damage into the finite element calculation software, and establishes the association between the macro numerical model and the micro numerical model through the homogenization method, so as to realize the prediction of the macro water damage mechanical properties from the micro structural characteristics of the asphalt mixture. This will provide a theoretical basis for the prediction of pavement water damage performance, the optimal design of the structure, and the pre-maintenance decision of the pavement, and has important guiding significance for the development of water-damage-resistant asphalt pavements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the asphalt pavement being affected by the combined effects of dynamic and static water;

[0028] Figure 2 This is a flow chart for constructing a macro- and micro-mechanical model of pavement water damage according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of an asphalt pavement RVE according to an embodiment of the present invention;

[0030] Figure 4 This is a flowchart of the application of a multi-scale model of asphalt pavement damage under the combined action of dynamic and static water according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The technical solution provided by this application will be further described below in conjunction with specific embodiments and accompanying drawings. The advantages and features of this application will become more apparent with reference to the following description.

[0032] Example 1

[0033] This embodiment provides a method for establishing a multi-scale model of asphalt pavement damage that takes into account the combined effects of dynamic and static water.

[0034] like Figure 1 、 Figure 2 As shown, this embodiment takes into account the long-term effects of static water and the short-term effects of dynamic water that asphalt pavement is subjected to during service, and establishes a mesoscopic mechanical model of water damage to asphalt mortar and a macroscopic mechanical model of water damage to asphalt mixture. Specifically, the following steps are included:

[0035] Step 1: Raw material selection and characterization of its physical and mechanical properties;

[0036] Specifically, in this example, SBS modified asphalt was selected, an AC-13 aggregate gradation was designed based on the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004), and a target void ratio of 6% was set, resulting in a mixture asphalt-to-rock ratio of 4.35. Asphalt mortar and asphalt mixture specimens were prepared using a gyratory compactor. Physical and mechanical properties of the asphalt mortar and asphalt mixture were measured based on the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). Physical and mechanical properties of the asphalt mortar and asphalt mixture were measured to determine physical and mechanical parameters such as dynamic modulus and Poisson's ratio.

[0037] Step 2: Design of water damage test for asphalt pavement materials;

[0038] Specifically, the damaging effects of water on asphalt pavement materials include two aspects: water diffusion under the long-term action of static water and scouring and pumping under the short-term action of dynamic water, such as Figure 1 As shown in the figure, the static water Marshall test (JTG E20-2011) was used to simulate the long-term damage caused by static water, and the water damage sensitivity test (ASTM D7870) was used to simulate the short-term damage caused by dynamic water. Based on the actual traffic volume of asphalt pavement, by controlling the immersion time and the number of dynamic water exposures, a "long-term water immersion + short-term dynamic water" water damage test was designed to consider the combined effects of static and dynamic water.

[0039] Step 3: Test and analysis of water damage characteristics of asphalt pavement materials;

[0040] Specifically, the asphalt mortar and asphalt mixture specimens were subjected to static water test, dynamic water test and static and dynamic water combined test respectively. Then, the rheological properties of the asphalt mortar were tested by dynamic rheometry (DSR), and the uniaxial compression dynamic modulus of the asphalt mixture specimens were tested using Superpave asphalt mixture performance test equipment (AMPT). The viscoelastic attenuation law of asphalt mortar and asphalt mixture under different water treatment conditions was obtained.

[0041] Step 4, determine the expression of comprehensive damage factors under the combined effects of dynamic and static water;

[0042] Based on the continuum damage mechanics and the water damage characteristics test data of asphalt pavement materials in step 3, the expressions of static water damage factor and dynamic water damage factor are determined based on the attenuation of dynamic modulus index, specifically:

[0043] (1)

[0044] (2)

[0045] Where, is the hydrostatic damage factor, is the dynamic modulus of asphalt mortar after hydrostatic action, is the initial dynamic modulus of asphalt mortar; is the dynamic water damage factor, is the dynamic modulus of asphalt mixture after water dynamics, is the initial dynamic modulus of asphalt mixture;

[0046] The test data were fitted to complete the superposition of static and dynamic water damage effects, and the expression of the comprehensive damage factor of the combined action of static and dynamic water was determined, specifically:

[0047] (3)

[0048] Where, It represents the comprehensive damage factor of the combined action of dynamic and static water; represents the dynamic water damage factor; Represents the hydrostatic damage factor.

[0049] Step 5: Establish a micromechanical model, including:

[0050] First, the hydrostatic damage factor based on the Maxwell model and step 4 , establish the water damage viscoelastic constitutive model of asphalt mortar; then:

[0051] Fick's second law is used to describe the diffusion of water in asphalt mortar, and a hydrostatic damage evolution model at the mesoscale is established.

[0052] The cohesive zone model (CZM) is used to describe the adhesion and cohesive damage.

[0053] Specifically, the water damage viscoelastic constitutive model of asphalt mortar based on the Maxwell model is:

[0054] (4)

[0055] Where, is stress, is the strain, E is the elastic modulus, is the viscosity coefficient, For time, is the hydrostatic damage factor in the mesoscopic model.

[0056] Specifically, the long-term effect of static water is water diffusion. Fick's second law is used to describe the diffusion of water in asphalt mortar, which is expressed as:

[0057] (5)

[0058] Where, is the diffusion coefficient of water in asphalt mortar; is the normalized moisture concentration in asphalt mortar; For the location;

[0059] The hydrostatic damage evolution model is:

[0060] (6)

[0061] Where, is the hydrostatic damage evolution process in the mesoscopic model, and is the inherent parameter of asphalt mortar; The concentration of humidity diffusion is related to time; is the hydrostatic damage factor in the mesoscopic model.

[0062] Specifically, in the micromechanical model, the adhesion and cohesive damage are characterized by the bilinear cohesive model (CZM).

[0063] Step 6: Establish a macroscopic mechanical model, including:

[0064] Based on the Maxwell model and the combined damage factor of dynamic and static water , establish the water damage viscoelastic constitutive model of asphalt mixture;

[0065] Fick's second law is used to describe the diffusion of water in asphalt mixtures, and a macroscopic hydrostatic damage evolution model is established.

[0066] The Biot consolidation theory is used to describe the pumping effect of water in asphalt mixture, and a macro-scale model of the dynamic water damage evolution process is established.

[0067] Specifically, the water damage viscoelastic constitutive model of asphalt mixture based on the Maxwell model is:

[0068] (8)

[0069] Where, is stress, is the strain, E is the elastic modulus, is the viscosity coefficient, is the comprehensive damage factor of the combined action of dynamic and static water in the macro model, For time.

[0070] Specifically, the long-term effect of static water is water diffusion. Fick's second law is used to describe the diffusion of water in asphalt mixture, which is expressed as:

[0071] (9)

[0072] Where, is the diffusion coefficient of water in asphalt mixture; is the normalized moisture concentration in asphalt mixture; For the location;

[0073] The hydrostatic damage evolution model in the macroscopic mechanical model is:

[0074] (10)

[0075] Where, is the hydrostatic damage evolution process in the macro model, and It is an inherent parameter of asphalt mixture and is calibrated through experiments; is the concentration of humidity diffusion, which is related to time; is the hydrostatic damage factor in the macroscopic model.

[0076] Specifically, the short-term effect of dynamic water is the pumping effect of water. The Biot consolidation theory is used to describe the pumping effect of water in asphalt mixture, which is expressed as:

[0077] (11)

[0078] Where, is the effective stress tensor; is the total stress tensor; is the Biot coefficient; is the pore water pressure; is the Crone symbol;

[0079] Assuming that dynamic water damage is related to the number of actions, the damage coefficient can be determined as a function of the number of actions. In the present invention, based on the coupled water-mechanical damage evolution equation, the dynamic water damage evolution process model in the macroscopic mechanical model is:

[0080] (12)

[0081] Where, is the evolution process of dynamic water damage in the macro model; and , k is the inherent parameter of asphalt mixture, which is calibrated through experiments; is the stress generated inside the mixture under the action of dynamic water; D is the damage variable; N is the number of dynamic water actions; is the damage factor of dynamic water action in the macro model.

[0082] The above-mentioned multi-scale model of asphalt pavement damage that considers the combined effects of dynamic and static water can be used to predict the macroscopic water damage performance of the pavement from the microscopic water damage characteristics of the asphalt mixture, providing a theoretical basis for the prediction of pavement water damage performance, structural optimization design, and pavement pre-maintenance decision-making.

[0083] Example 2

[0084] Based on the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water in the above-mentioned embodiment 1, this embodiment further proposes a method for predicting water damage to asphalt pavement. This method uses simulation software to establish a macroscopic numerical model of the pavement structure and a microscopic numerical model of the asphalt mixture, and establishes an association between the macroscopic numerical model of the pavement structure and the microscopic numerical model of the asphalt mixture through a homogenization method. Finally, the numerical analysis of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water is completed, thereby realizing the prediction of water damage to asphalt pavement.

[0085] like Figure 3 、 Figure 4 As shown, the specific steps include:

[0086] Step S1: Selecting the asphalt pavement's representative volume element (RVE) as the mesoscopic numerical model of the asphalt mixture. The geometric scale of the asphalt pavement's REV is 50 mm x 50 mm. In the mesoscopic numerical model, the aggregate is defined as an elastic material, and the asphalt mortar is defined as a viscoelastic material. The bond damage at the interface between the aggregate and the asphalt mortar, as well as the cohesive damage within the asphalt mortar, are characterized using the CZM model.

[0087] At the same time, a macroscopic numerical model of the asphalt pavement structure was established with geometric dimensions of 6m wide and 3m high. The top layer is an asphalt mixture surface layer (asphalt surface layer) with a thickness of 18cm; the second is a semi-rigid cement-stabilized gravel base layer (pavement base layer) with a thickness of 60cm; and the bottom layer is a soil base layer (roadbed) with a thickness of 222cm.

[0088] Step S2: Based on the microscopic numerical model and macroscopic numerical model of step S1, the water damage viscoelastic constitutive model of asphalt mortar (as shown in formula (4)) and the water damage viscoelastic constitutive model of asphalt mixture (as shown in formula (8)) are written into the finite element UMAT subroutine respectively to realize the numerical calculation of the macroscopic and microscopic water damage model under the combined action of dynamic and static water.

[0089] Step S3: The fine numerical model and the macro numerical model are linked by the homogenization method to complete the numerical analysis of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water.

[0090] Specifically, based on the Mori-Tanaka micromechanics method, the uniform stiffness tensor of asphalt mixture is determined. The general idea of the homogenization method is:

[0091] (13)

[0092] Where: for The volume average value (equal to the macroscopic function); is a function at the local microscopic scale; is the volume of RVE.

[0093] The homogenization method is used to establish the relationship between the microscopic numerical model and the macroscopic numerical model, including:

[0094] Step S3.1: Apply reasonable boundary conditions to the macroscopic numerical model established in step S1. Considering that the real road surface is approximately an infinitely long plate structure, rigid constraints are applied to the side boundaries of the macroscopic numerical model. The lower surface is supported and also has rigid constraints. No constraints are applied to the upper surface.

[0095] Step S3.2: Based on step S2, the water-damaged viscoelastic constitutive model of asphalt mixture is used to calculate the stress-strain response of the macroscopic numerical model under the action of dynamic water;

[0096] Step S3.3: Use the stress-strain response results of the macroscopic numerical model in step S3.2 as the boundary conditions of the microscopic numerical model, impose boundary constraints on the selected RVE, calculate the non-uniform stress-strain response of the RVE, and use the homogenization method to homogenize the stress-strain response to obtain the macroscopic equivalent stress-strain response of the asphalt pavement.

[0097] Step S4: Based on the macro-equivalent stress-strain response of the asphalt pavement, the macro-equivalent elastic parameters of the asphalt pavement are calculated to predict the water damage performance of the asphalt pavement.

[0098] Specifically, the multi-scale model of asphalt pavement that considers the combined effects of dynamic and static water includes a viscoelastic constitutive model in its microscopic mechanical model that includes the time variable of static water damage, and a viscoelastic constitutive model in its macroscopic mechanical model that includes the time variable of dynamic water damage. By calculation, the macroscopic equivalent elastic parameters of the asphalt pavement under the effects of static water and dynamic water at different times can be obtained, thereby realizing the performance prediction of the asphalt pavement under different water damage conditions.

[0099] The above description is only a description of the preferred embodiments of the present application and does not limit the scope of the present application. Any changes or modifications made by any person skilled in the art based on the above disclosed technical content should be regarded as equivalent valid embodiments and fall within the scope of protection of the technical solution of the present application.

Claims

1. A method for establishing a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water, characterized in that: The multi-scale model includes a microscopic mechanical model and a macroscopic mechanical model, and the establishment method includes the following steps: Step 1: Selection of raw materials for asphalt mortar and asphalt mixture and characterization of physical and mechanical properties, specifically: Select asphalt type, aggregate gradation, void ratio and asphalt-to-stone ratio parameters, prepare asphalt mortar specimens and asphalt mixture specimens using a rotary compactor, and obtain physical and mechanical parameters of the asphalt mortar and asphalt mixture through physical and mechanical property tests, the physical and mechanical parameters including but not limited to dynamic modulus and Poisson's ratio; Step 2: Design of water damage test for asphalt pavement materials; Step 3: Experimental analysis of water damage characteristics of asphalt pavement materials; Step 4: Determine the static water damage factor based on continuum damage mechanics and water damage characteristics test data of asphalt pavement materials , dynamic water damage factor , comprehensive damage factor of dynamic and static water , specifically: Based on the attenuation of the dynamic modulus index, the expression of the static water damage factor and the dynamic water damage factor is determined respectively, which is expressed as: （1） （2） Where, is the hydrostatic damage factor, is the dynamic modulus of asphalt mortar after hydrostatic action, is the initial dynamic modulus of asphalt mortar; is the dynamic water damage factor, is the dynamic modulus of asphalt mixture after water dynamics, is the initial dynamic modulus of asphalt mixture; The test data were fitted to complete the superposition of static and dynamic water damage effects, and the expression of the comprehensive damage factor of the combined action of static and dynamic water was determined, which is expressed as: （3） Where, It represents the comprehensive damage factor of the combined action of dynamic and static water; represents the dynamic water damage factor; represents the hydrostatic damage factor; Step 5: Establish a micromechanical model, including: based on the Maxwell model and the hydrostatic damage factor , a viscoelastic constitutive model of water damage to asphalt mortar was established; Fick's second law was used to describe the diffusion of water in asphalt mortar, and a model of the hydrostatic damage evolution process at the mesoscale was established; a cohesive force model was used to describe the bonding and cohesive damage, specifically: The water damage viscoelastic constitutive model of asphalt mortar established based on the Maxwell model is: （4） Where, is stress, is the strain, E is the elastic modulus, is the viscosity coefficient, For time, is the hydrostatic damage factor in the mesoscopic model; The long-term effect of static water is water diffusion. Fick's second law is used to describe the diffusion of water in asphalt mortar, which is expressed as: （5） Where, is the diffusion coefficient of water in asphalt mortar; is the normalized moisture concentration in asphalt mortar; For the location; The hydrostatic damage evolution model is: （6） Where, is the hydrostatic damage evolution process in the mesoscopic model, and is the inherent parameter of asphalt mortar; The concentration of humidity diffusion is related to time; is the hydrostatic damage factor in the mesoscopic model; Step 6: Establish a macroscopic mechanical model, including: a comprehensive damage factor based on the Maxwell model and the combined action of dynamic and static water , a viscoelastic constitutive model of water damage in asphalt mixture is established; Fick's second law is used to describe the diffusion of water in asphalt mixture, and a model of the evolution process of static water damage on a macro scale is established; Biot's consolidation theory is used to describe the pumping effect of water in asphalt mixture, and a model of the evolution process of dynamic water damage on a macro scale is established; specifically: The water damage viscoelastic constitutive model of asphalt mixture based on Maxwell model is: （8） Where, is stress, is the strain, E is the elastic modulus, is the viscosity coefficient, is the comprehensive damage factor of the combined action of dynamic and static water in the macro model, For time; The long-term effect of static water is water diffusion. Fick's second law is used to describe the diffusion of water in asphalt mixture, which is expressed as: （9） Where, is the diffusion coefficient of water in asphalt mixture; is the normalized moisture concentration in asphalt mixture; For the location; The hydrostatic damage evolution model in the macroscopic mechanical model is: （10） Where, is the hydrostatic damage evolution process in the macro model, and It is an inherent parameter of asphalt mixture and is calibrated through experiments; is the concentration of humidity diffusion, which is related to time; is the hydrostatic damage factor in the macroscopic model; The short-term effect of dynamic water is the pumping effect of water. The Biot consolidation theory is used to describe the pumping effect of water in asphalt mixture, which is expressed as: （11） Where, is the effective stress tensor; is the total stress tensor; is the Biot coefficient; is the pore water pressure; is the Crone symbol; The evolution model of hydrodynamic damage in the macroscopic mechanical model is: （12） Where, is the evolution process of dynamic water damage in the macro model; and , k is the inherent parameter of asphalt mixture, which is calibrated through experiments; is the stress generated inside the mixture under the action of dynamic water; D is the damage variable; N is the number of dynamic water actions; is the damage factor of dynamic water action in the macro model.

2. The method for establishing a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water according to claim 1, characterized in that: Step 2: The static water Marshall test is used to simulate the long-term damage of static water, and the water damage sensitivity test is used to simulate the short-term damage of dynamic water. Based on the actual traffic volume of asphalt pavement, by controlling the immersion time and the ratio of the number of dynamic water effects, a "long-term water immersion + short-term dynamic water" water damage test is designed to consider the combined effects of static and dynamic water.

3. The method for establishing a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water according to claim 1, characterized in that: Step 3: The asphalt mortar and asphalt mixture specimens were subjected to static water test, dynamic water test and static and dynamic water combined test respectively. Then, the rheological properties of the asphalt mortar were tested by a dynamic rheological shear instrument, and the uniaxial compression dynamic modulus of the asphalt mixture specimens were tested using Superpave asphalt mixture performance testing equipment. The viscoelastic attenuation law of asphalt mortar and asphalt mixture under different water treatment conditions was obtained.

4. An application of a multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water, characterized in that: The multi-scale model is established using the method according to claim 1, and asphalt pavement water damage prediction is achieved based on the multi-scale model.

5. The application of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water as claimed in claim 4, characterized in that: The prediction of asphalt pavement water damage based on the multi-scale model includes the following steps: Step S1: The RVE of the asphalt pavement is selected as the mesoscopic numerical model of the asphalt mixture. In the mesoscopic numerical model, the aggregate is defined as an elastic material, the asphalt mortar is defined as a viscoelastic material, and the bonding damage at the interface between the aggregate and the asphalt mortar and the cohesive damage within the asphalt mortar are both characterized using the CZM model; At the same time, a macroscopic numerical model of the asphalt pavement structure is established, in which: the top layer is the asphalt mixture surface layer; the second is the semi-rigid cement stabilized gravel base layer; and the bottom layer is the soil base layer; Step S2: Based on the mesoscopic numerical model and macroscopic numerical model from step S1, the water damage viscoelastic constitutive model of asphalt mortar and the water damage viscoelastic constitutive model of asphalt mixture are written into the finite element UMAT subroutine respectively to realize the numerical calculation of the macroscopic and microscopic water damage models under the combined action of dynamic and static water. Step S3: The fine numerical model and the macro numerical model are linked by a homogenization method to complete the numerical analysis of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water; Step S4: Based on the macro-equivalent stress-strain response of the asphalt pavement, the macro-equivalent elastic parameters of the asphalt pavement are calculated to predict the water damage performance of the asphalt pavement.

6. The application of the multi-scale model of asphalt pavement damage considering the combined effects of dynamic and static water as claimed in claim 5, characterized in that: The step S3, establishing the association between the microscopic numerical model and the macroscopic numerical model by a homogenization method, specifically includes: Step S3.1 applies boundary conditions to the macroscopic numerical model established in step S1; Step S3.2: Based on step S2, the water-damaged viscoelastic constitutive model of asphalt mixture is used to calculate the stress-strain response of the macroscopic numerical model under the action of dynamic water; Step S3.3: Use the stress-strain response results of the macroscopic numerical model in step S3.2 as the boundary conditions of the microscopic numerical model, impose boundary constraints on the selected RVE, calculate the non-uniform stress-strain response of the RVE, and use the homogenization method to homogenize the stress-strain response to obtain the macroscopic equivalent stress-strain response of the asphalt pavement.

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