A long-life asphalt pavement design method based on performance interval inversion of material structure integration

Abstract

This application discloses a material-structure integrated long-life asphalt pavement design method based on performance range inversion, belonging to the field of road engineering technology. The method includes the following steps: (1) engineering input and initial structural selection; (2) structural response analysis and calculation of three types of failure indices; (3) construction of three types of failure utilization rate models; (4) construction of a unified performance boundary function; (5) material performance range inversion; (6) material performance database screening; (7) establishment of a full life cycle cost model; (8) material-structure joint optimization design. This invention takes the structural stress and target life as premises, reversely calculates the required material performance range of each structural layer, and carries out multi-constraint optimization on this basis to realize the system coupling design of materials and structures.

Description

Technical Field

[0001] This application relates to a material-structure integrated long-life asphalt pavement design method based on performance range inversion, which belongs to the field of road engineering technology. Background Technology

[0002] Asphalt pavement is the most widely used structural form in transportation infrastructure, and its service performance and lifespan directly affect road operation safety and traffic efficiency. With the continuous increase in transportation intensity and the rising proportion of heavy-load traffic, pavements are more prone to various defects such as fatigue cracking, rutting deformation, and low-temperature cracking during long-term service. Meanwhile, the concept of "long-life roads" is gradually becoming the industry's development direction, requiring the design phase to consider material properties, structural stress, and future maintenance needs, ensuring stable performance throughout the pavement's life cycle and reducing maintenance costs. Although current design methods have formed a mature system, they still aim to meet the minimum requirements of specifications and have not yet fully adapted to the needs of long-life, high-reliability road construction.

[0003] The current design process in the "Specification for Design of Asphalt Pavement of Highways" (JTG D50-2017) is mainly as follows: first, the structural form is selected based on the road grade and experience; then, commonly used or modified asphalt mixtures are selected as surface and base course materials; finally, indicators such as fatigue, rutting, and low-temperature cracking are checked item by item. In this process, material properties are assumed to be constants as initial input parameters, and designers can only adjust the structural thickness to meet the specification requirements under given material conditions. This linear model of "structure first, material second" makes it difficult to propose material performance requirements based on the specific structural stress state, which can easily lead to insufficient material performance in critical layers and excessive material performance in non-critical layers. In addition, different models are used to check failure modes such as fatigue, permanent deformation, and low-temperature cracking, lacking a unified evaluation scale, which is not conducive to determining the main control failure and also increases the design complexity.

[0004] In recent years, although some studies have attempted to estimate the structural layer modulus through back-calculation methods, such as patent CN114164721A, which, under given material parameters, uses the thickness of the subgrade reinforcement layer as the independent variable and the thickness of the asphalt layer as the dependent variable, and optimizes different thickness combinations through fatigue and other damage control and cost comparison, it is essentially an economic thickness design under a given design life, and its material parameters are all predetermined. Patent CN118171360A, targeting roads already in service, calculates the existing structural modulus through deflection back-calculation, calculates the remaining equivalent axle load cycles, determines the minimum dynamic compression modulus of the maintenance layer without changing the road surface elevation, and establishes a fatigue equation using indirect tensile modulus and thermal shrinkage coefficient to enable the road to reach its original design life, it has already determined the structural layer thickness and does not involve the road's initial design. Existing technological achievements have not yet formed a material performance range inversion method that can be used in the design stage, let alone established a unified technical system with material database screening and full life cycle cost analysis. Therefore, under the current design system, it is difficult to achieve organic coordination between material selection, structural design and life prediction, and it is also difficult to ensure the long service life of asphalt pavement from the design source. Summary of the Invention

[0005] To address the aforementioned issues, a material-structure integrated long-life asphalt pavement design method based on performance range inversion is proposed. This method achieves inverse calculation of material performance parameters, screening of material databases, and collaborative optimization of structure, materials, lifespan, and cost by constructing a unified constraint model with multiple failure modes.

[0006] According to the first aspect of this application, this application provides a material-structure integrated long-life asphalt pavement design method based on performance range inversion, comprising the following steps:

[0007] (1) Engineering input and preliminary structural selection

[0008] Obtain the road grade, design service life, traffic load grade, and cumulative number of standard axle load applications N within the design life. design ;

[0009] Collect environmental temperature data for the project area over the past 10 years to determine the representative temperature range to be used;

[0010] Obtain the bearing capacity indicators of the subgrade, including the resilient modulus of the subgrade, the pavement surface layer structure, and the thickness of each structural layer;

[0011] (2) Structural response analysis and calculation of three types of failure indices

[0012] Under the structural system and environmental conditions set in step 1, the key mechanical responses, including the tensile strain ε at the bottom of the i-th layer, are calculated based on the multilayer elastic system theory program. t,i and the vertical compressive stress σ at the top of the i-th layer z,iAnd calculate the fatigue life N of the i-th layer respectively. f,i The permanent deformation R of the i-th layer structure a,i Low-temperature cracking index (CI) of asphalt surface layer;

[0013] (3) Construct three types of failure utilization models

[0014] The fatigue life, permanent deformation, and low-temperature cracking indices are dimensionless and defined as follows:

[0015] Fatigue failure utilization rate: ;where N f,i Let be the fatigue life of the i-th layer;

[0016] Permanent deformation failure utilization rate: , where R limit The allowable permanent deformation is determined according to the specifications, and n is the number of structural layers;

[0017] Low-temperature cracking failure utilization rate: CI limit The permissible low-temperature cracking index is determined according to the specifications;

[0018] (4) Construct a unified performance boundary function

[0019] Based on the three types of utilization rates obtained in step (3), a unified performance boundary function F is constructed: ;

[0020] (5) Material property range inversion

[0021] With the thickness of each structural layer and N fixed design Under the condition of F≤0.8, the material performance parameters in the three types of failure utilization models in step (3) are taken as unknowns, and their reasonable engineering range is taken as the initial domain to obtain the material performance parameter range that meets the constraint conditions.

[0022] (6) Screening of material property database

[0023] The material performance parameter range obtained in step (5) is compared with the material performance database item by item, and the set of all material types that meet the range conditions, Candidate_i, is selected.

[0024] (7) Establish a life-cycle cost model (LCC)

[0025] Where C0 is the initial construction cost, and Cm j For the cost of the jth maintenance, Cu j Let t be the user delay cost for the j-th time, r be the discount rate, and t be the cost of delay for the user. j The time of the j-th maintenance is when it occurs;

[0026] (8) Material-structure joint optimization design

[0027] ①Outer layer optimization

[0028] Select a material type from Candidate_i, calculate the corresponding LCC value based on the material type and the structural layer thickness, and use the material type and structural layer thickness corresponding to the minimum LCC value as the structure-material scheme;

[0029] ②Inner layer verification

[0030] Recalculate U based on the structure-material scheme obtained from the outer layer optimization. f U r U CI The unified performance boundary function F is used. If F ≤ 0.8, the scheme meets the life requirement and enters the candidate set; if F > 0.8, the structural layer thickness, material type or corresponding performance parameter range is adjusted until F ≤ 0.8 is met.

[0031] Step (1) Based on the requirements of the "Specification for Design of Asphalt Pavement of Highway" (JTG D50-2017) (hereinafter referred to as the Specification) regarding structural combination design, a preliminary selection of the pavement surface layer structure is made. No specific material performance parameters are preset. The required parameters will be obtained through performance inversion in subsequent steps.

[0032] The three performance indicators in step (2) can be uniformly constructed as a functional expression determined by the material performance parameters (fatigue parameters, permanent deformation parameters and low temperature parameters) and the structural mechanical response, which can be used as the mathematical basis for utilization calculation and performance range inversion.

[0033] Steps (3) and (4) unify the three different dimensions of indicators—fatigue life, permanent deformation, and low-temperature cracking—into dimensionless and construct a single performance boundary function. The purpose is to provide a unified constraint basis for "performance range inversion—material library screening—LCC optimization," rather than simple data normalization. By making the three failures dimensionless, a single criterion is merged, and the performance range of each layer of materials is inverted based on this criterion. The life redundancy is controlled with F≤0.8, and a two-layer optimization scheme is embedded. This application thus realizes the transformation of material performance from "input parameters" to "parameters to be determined," and completes the performance range inversion and the collaborative optimization of long life and full life cycle cost under given structural and life conditions.

[0034] When F≤1, the structure can meet the triple constraints of fatigue life, permanent deformation and low temperature cracking. However, this application further requires F≤0.8, which is equivalent to fatigue life being at least 25% higher than the minimum requirement; permanent deformation being at least 20% lower than the allowable limit; and the low temperature cracking safety margin being increased by at least 20%.

[0035] In step (1), under the design of each structural layer thickness range, step (5) fixes the specific structural layer thickness and N. design Different thicknesses and N were obtained. design Combining these elements, with F≤0.8 as the constraint, we obtain the relationship between different thicknesses of each structural layer and N. design The range of material property parameters that satisfy the constraints under the combination of conditions.

[0036] Step (6) selects all material sets Candidate_i that meet the interval conditions for each structural layer, realizes the quantitative selection of material types, and transforms the material selection from experience-based judgment to a traceable screening process based on performance intervals.

[0037] The life cycle cost model (LCC) constructed in step (7) includes the initial construction cost, the maintenance cost at each maintenance time point in the life cycle, and the user delay cost caused by maintenance, so as to achieve synergistic optimization of economic efficiency and life performance.

[0038] Step (8) Through two-layer optimization, a design result that combines life reliability, material rationality and economy is formed, realizing a long-life design that integrates materials and structure.

[0039] Optionally, the road surface structure layer in step (1) includes a top layer, a middle layer, and a bottom layer.

[0040] Optionally, the fatigue life N of the i-th layer in step (2) f,i The calculation formula is: ,

[0041] In the formula, β—target reliability index;

[0042] k a —Adjustment coefficient for seasonally frozen soil areas;

[0043] k b,i — Fatigue loading mode coefficient of the i-th asphalt mixture;

[0044] k T1 —Temperature adjustment factor;

[0045] ε t,i —Tensile strain at the bottom of the i-th layer of the asphalt mixture;

[0046] E ′′ i —The dynamic compression modulus of the i-th asphalt mixture at 20°C;

[0047] VFA i —Asphalt saturation of the i-th asphalt mixture.

[0048] Specifically, the value of β is determined according to the design standards specified in the specifications based on the highway grade.

[0049] Specifically, the k a Determined according to Appendix B of the specification.

[0050] Specifically, the k b,i The calculation formula is: , where h i Let be the thickness of the i-th layer of the asphalt mixture.

[0051] Specifically, the k T,i Determined according to Appendix G in the specification.

[0052] Specifically, the ε t,i The calculation formula is: p is the tire ground contact pressure under standard axle load, δ is the equivalent circle radius, E0 is the resilient modulus of the roadbed top surface, h1, h2…h n-1 E1, E2…E represents the thickness of each structural layer. n-1 Let f(*) represent the modulus of each structural layer. The function f(*) represents the horizontal tensile strain structural response function at the bottom of the layer under the theory of multilayer elastic systems. Its specific solution can be achieved through existing multilayer elastic system calculation programs.

[0053] Specifically, the existing multi-layered elastic system calculation programs are BISAR 3.0, HPDS2017, and DKDAPD online pavement structure design system.

[0054] Specifically, the VFA i The value of should meet the requirements of the specification.

[0055] Optionally, the permanent deformation R of the i-th layer structure described in step (2) a,i The calculation formula is: ,

[0056] In the formula, k R,i —Comprehensive correction factor for the i-th layer of asphalt mixture;

[0057] T pef —Equivalent temperature of permanent deformation of asphalt mixture layer;

[0058] σ z,i —Vertical compressive stress at the top of the i-th layer of the asphalt mixture;

[0059] N e3 —The cumulative number of times the equivalent design axle load is applied on the design lane within the design service life or from the opening to the first rut repair;

[0060] h i —Thickness of the i-th layer;

[0061] h0—thickness of the rutting test specimen;

[0062] R 0,i —The permanent deformation of the i-th layer of asphalt mixture under rutting test at a test temperature of 60°C, a pressure of 0.7MPa, and 2520 loading cycles.

[0063] Specifically, the k R,i The calculation formula is: , where h a Z represents the thickness of the asphalt mixture layer. i The depth of the i-th layer of the asphalt mixture is taken as 15mm for the first layer and the depth of the other layers is the distance from the midpoint of the road surface to the layer.

[0064] Specifically, the T pef Determined according to Appendix G in the specification.

[0065] Specifically, the σ z,i The calculation formula is: The function f(*) represents the structural response function of vertical compressive stress on the top surface of the asphalt mixture layer under the multilayer elastic system theory. Its specific solution can be achieved through the existing multilayer elastic system calculation program.

[0066] Specifically, the N e3 Calculated according to Appendix A of the specification.

[0067] Optionally, the formula for calculating the low-temperature cracking index CI of the asphalt pavement in step (2) is: ,

[0068] In the formula, S t — Creep stiffness of surface asphalt flexural beam under a 180s loading condition of low pavement design temperature plus 10°C test temperature;

[0069] b—Subgrade type parameter;

[0070] T—Road surface low-temperature design temperature, which is the average of the lowest temperatures over 10 consecutive years;

[0071] h a —Thickness of asphalt mixture layer.

[0072] In the calculation of the above three types of failure indices, apart from the material performance parameters that need to be obtained through inversion, the remaining parameters and coefficients are predetermined inputs, including fixed or recommended coefficients given by the specifications (such as asphalt saturation, temperature adjustment coefficient, etc.), and engineering design conditions already specified in step 1 (such as the roadbed resilient modulus and the thickness of each structural layer). The above-mentioned known parameters ensure the feasibility of the inversion process and the determinism of the calculation chain.

[0073] Optionally, the material performance parameters mentioned in step (5) include fatigue parameters, permanent deformation parameters and low-temperature performance parameters.

[0074] Optionally, the range of material performance parameters in step (5) includes:

[0075] 1) The dynamic compression modulus range of the i-th asphalt mixture [E] ′′ i_min E ′′ i_max ];

[0076] 2) The range of permanent deformation of the i-th asphalt mixture [R] 0_i_min R 0_i_max ];

[0077] 3) Creep stiffness range of surface asphalt layer [S] t-min S t-max ].

[0078] Optionally, the method for obtaining the material performance parameter range that satisfies the constraint conditions in step (5) is as follows: the dynamic compression modulus range of the i-th layer asphalt mixture is E ′′ i_min E represents the minimum dynamic compressive modulus required for each material type in the specification. ′′ i_max Through The formula calculates the permanent deformation range R of the i-th asphalt mixture. 0_i_min 0mm, R 0_i_max pass The formula calculates that S is in the creep stiffness range of the surface layer asphalt. t-min The range is 120-300MPa, S t-max pass The formula is used for calculation.

[0079] Optionally, the material type in step (6) is asphalt material, which includes at least one of aggregate, mineral powder and fiber.

[0080] Specifically, the aggregate includes at least one of natural aggregate, artificial aggregate, and recycled aggregate, wherein the natural aggregate is crushed stone, gravel, or sand, the artificial aggregate is steel slag aggregate or slag aggregate, and the recycled aggregate is recycled asphalt mixture aggregate.

[0081] Specifically, the mineral powder includes at least one of limestone mineral powder, manufactured sand mineral powder, and industrial by-product mineral powder.

[0082] Specifically, the fiber includes at least one of lignin fiber, mineral fiber, and synthetic fiber.

[0083] According to a second aspect of this application, this application provides the application of the material structure integrated long-life asphalt pavement design method based on performance range inversion as described above in the design of asphalt pavement structures.

[0084] The beneficial effects of this application include, but are not limited to:

[0085] 1. According to the material-structure integrated long-life asphalt pavement design method based on performance range inversion in this application, by constructing a unified constraint model for multiple failure modes, the material performance parameters can be inversely calculated, the material database can be screened, and the structure-material-life-cost can be synergistically optimized.

[0086] 2. The material-structure integrated long-life asphalt pavement design method based on performance range inversion of this application differs from the traditional linear design process that uses predetermined material parameters for verification. This invention takes structural stress and target life as prerequisites, reverse-engineers the required material performance range for each structural layer, and carries out multi-constraint optimization on this basis to realize the system coupling design of materials and structure.

[0087] 3. Based on the material structure integrated long-life asphalt pavement design method based on performance range inversion in this application, the long-life design requirements of asphalt pavement are achieved by constructing three types of failure utilization rate models and a unified performance boundary function F, and limiting F≤0.8.

[0088] 4. According to the material-structure integrated long-life asphalt pavement design method based on performance range inversion in this application, by unifying the three different dimensions of indicators—fatigue life, permanent deformation, and low-temperature cracking—into dimensionless, the three failures are merged into a single criterion, and the performance range of each layer of materials is inversely calculated based on this criterion. The life redundancy is controlled by F≤0.8 and a two-layer optimization scheme is embedded, thereby realizing the transformation of material performance from "input parameters" to "parameters to be determined". Under given structural and life conditions, the performance range inversion and the synergistic optimization of long life and full life cycle cost are completed.

[0089] 5. According to the material-structure integrated long-life asphalt pavement design method based on performance range inversion of this application, through two-layer optimization, a design result that combines life reliability, material rationality and economy is formed, realizing the material-structure integrated long-life design. Attached Figure Description

[0090] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0091] Figure 1This is a basic flowchart of the material-structure integrated long-life asphalt pavement design method based on performance range inversion proposed in this application. Detailed Implementation

[0092] The present application is described in detail below with reference to specific embodiments, but it is not intended to limit the scope of protection of the present invention.

[0093] Unless otherwise specified, the methods used in the embodiments of this application are conventional methods in the prior art.

[0094] Example 1

[0095] This embodiment uses a Class I highway in Shandong Province as an example to describe the technical solution of the present invention in detail. The basic flowchart of the material-structure integrated long-life asphalt pavement design method based on performance range inversion is shown below. Figure 1 The details are as follows:

[0096] This embodiment relates to a material-structure integrated long-life asphalt pavement design method based on performance range inversion, including the following steps:

[0097] (1) Engineering input and preliminary structural selection

[0098] (1.1) Traffic conditions and pavement performance indicators

[0099] Road grade: Class I highway

[0100] • Design lifespan: 15 years

[0101] Traffic load rating: Heavy traffic

[0102] • Total number of equivalent standard axle loads during the design period:

[0103] N design =1.2×10 8 Second-rate

[0104] • Permissible permanent deformation of asphalt mixture layers:

[0105] R limit =15mm

[0106] • Permissible low-temperature cracking index of asphalt mixture layer:

[0107] CI limit =3

[0108] (1.2) Ambient temperature parameters (statistics over the past 10 years)

[0109] Average annual temperature: 12.7℃

[0110] Average temperature of the hottest month: 26.0℃

[0111] • Average annual minimum temperature:

[0112] T=-12.0℃

[0113] As determined by Appendix G of the "Specifications for Design of Asphalt Pavement of Highways" (JTG D50-2017):

[0114] • Temperature adjustment factor:

[0115] k T1 =1.21

[0116] • Equivalent temperature of permanent deformation of asphalt mixture layer:

[0117] T pef =19.7ºC

[0118] (1.3) Preliminary selection of roadbed conditions and structure

[0119] The roadbed in the area is dry, and the soil is well-graded sand. According to the specifications, the following should be taken:

[0120] E0=150MPa

[0121] Without pre-setting material performance parameters, the initial selection of structural combinations was conducted according to the specifications, and the pavement structure was determined as shown in Table 1:

[0122] Table 1 Road Structure

[0123]

[0124] Asphalt mixture layer thickness:

[0125] h a =180mm

[0126] (2) Structural response analysis and calculation of three types of failure indices

[0127] (2.1) Structural response analysis

[0128] Under the aforementioned structural system, subgrade conditions, and traffic load conditions, the key mechanical responses of each layer of the asphalt mixture were obtained using the multi-layer elastic system theory calculation program (DKDAPD system), as shown in Table 2.

[0129] Table 2 Key Mechanical Responses of Asphalt Mixture Layers

[0130]

[0131] (2.2) Fatigue life calculation

[0132] The fatigue life model of this invention is adopted:

[0133]

[0134] The possible values ​​are as follows:

[0135] ·β=1.28

[0136] ·k a =1.00

[0137] ·k T1 =1.21

[0138] • Upper layer VFA1=78%

[0139] Mid-layer VFA2=68%

[0140] The bottom layer VFA3=65%

[0141] ·k b,i Calculated using the formula of this invention;

[0142] ·E ′′ i The dynamic compression modulus of each layer of asphalt mixture at 20℃ is used as an unknown quantity for inverting the material property range.

[0143] After substitution and rearrangement, the relationship between fatigue life and modulus for each layer is obtained, as shown in Table 3:

[0144] Table 3 Relationship between fatigue life and modulus of each layer

[0145]

[0146] (2.3) Calculation of permanent deformation

[0147] The permanent deformation model of this invention is adopted:

[0148]

[0149] in,

[0150] ·T pef =19.7ºC, h1 / h2 / h3=40mm / 60mm / 80mm;

[0151] ·N e3 =1.01×10 8 Second-rate;

[0152] h0 = 50 mm;

[0153] ·k Ri Calculated using the formula of this invention. Where z1 / z2 / z3 = 15mm / 70mm / 140mm; h a =180mm;

[0154] ·R 0,iThis represents the permanent deformation from the rutting test, serving as an unknown quantity for inverting the material's property range.

[0155] After substituting the parameters, we obtain Table 4:

[0156] Table 4. Relationship between permanent deformation of each layer and permanent deformation in rutting tests.

[0157]

[0158] (2.4) Calculation of Low Temperature Cracking Index (CI)

[0159] The CI model of this invention is adopted:

[0160]

[0161] in,

[0162] b=5;

[0163] ·T=-12°C, h a =180mm;

[0164] ·S t The surface layer asphalt creep stiffness is used as an unknown quantity in the inversion.

[0165] Simplifying, we get:

[0166]

[0167] (3) Construct three types of failure utilization models

[0168] The utilization rates of three types of failures—fatigue, permanent deformation, and low-temperature cracking—are dimensionless to obtain utilization rate models for these three types of failures:

[0169] (3.1) Fatigue failure utilization rate

[0170]

[0171] (3.2) Permanent deformation failure utilization rate

[0172]

[0173] (3.3) Low-temperature cracking failure utilization rate

[0174]

[0175] (4) Construct a unified performance boundary function

[0176]

[0177] The pavement structure must be able to simultaneously meet the control requirements for three types of failures—fatigue, permanent deformation, and low-temperature cracking—during its design life, and must have a certain safety redundancy.

[0178] (5) Results of material property range inversion

[0179] With fixed structural layer thickness and N design Under the condition of F≤0.8, the material performance parameters are inverted to obtain the performance range that satisfies the constraint as follows.

[0180] (5.1) Dynamic compression modulus range

[0181] Constrained by fatigue failure utilization rate

[0182]

[0183] Based on the specifications, the dynamic compression modulus range of each structural layer of asphalt mixture at 20℃ was obtained through inversion:

[0184] • Top layer:

[0185]

[0186] • Middle layer:

[0187]

[0188] • Bottom layer:

[0189]

[0190] (5.2) Range of permanent deformation in rutting test

[0191] Constrained by the utilization rate of permanent deformation failure:

[0192]

[0193] And take the allowable permanent deformation amount:

[0194]

[0195] The total permanent deformation constraint of the asphalt mixture layer can be obtained as follows:

[0196]

[0197] Combining the relation obtained in step (2.3), we can derive:

[0198]

[0199] Under the premise of satisfying the above general constraints, the reasonable range of permanent deformation values ​​for each rutting test layer can be expressed as follows:

[0200] • Top layer:

[0201]

[0202] • Middle layer:

[0203]

[0204] • Bottom layer:

[0205]

[0206] When S t-min When the endpoint value is [120, 300] MPa, the requirements of this application can also be met.

[0207] (5.3) Creep stiffness range of surface layer asphalt

[0208] Constrained by low-temperature cracking failure utilization rate:

[0209]

[0210] And take the allowable low temperature cracking index:

[0211]

[0212] The low-temperature cracking control condition can be expressed as:

[0213]

[0214] Combining the low-temperature cracking index model in step (2.4), the reasonable range of creep stiffness for the surface layer asphalt is obtained through inversion:

[0215]

[0216] (5.4) Explanation of the interval inversion results

[0217] The aforementioned material performance ranges are not isolated values, but rather collaborative ranges formed under the constraints of a unified performance boundary function. Within this range, any set of material performance parameters can be selected, and as long as the three types of constraints—fatigue, permanent deformation, and low-temperature cracking—are simultaneously satisfied, it can be ensured that the structure has sufficient safety redundancy during its design life. This provides a clear and executable criterion basis for subsequent material performance database screening and material-structure joint optimization.

[0218] (6) Screening of material property database

[0219] The material performance parameter ranges obtained in step (5) are compared item by item with the material performance database to select all material types that meet the range conditions, set Candidate_i. Since there are many material types that meet the range conditions, they are not listed here. In this embodiment, considering the fatigue performance, permanent deformation performance and low temperature performance of the three-layer asphalt mixture, and combining the material cost, construction adaptability and maintenance characteristics during the service life, the materials that meet the performance range requirements are combined to form the following three feasible structure-material schemes.

[0220] Option I: Balanced performance option (benchmark option), as shown in Table 5:

[0221] Table 5 Scheme I

[0222]

[0223] Option II: High-durability option, as shown in Table 6:

[0224] Table 6 Scheme II

[0225]

[0226] Option III: The economically optimized option, as shown in Table 7:

[0227] Table 7 Scheme III

[0228]

[0229] (7) Calculation of total life cycle cost

[0230] In satisfying Under the premise of ≤0.8, a life cycle cost analysis is performed on the above material-structure scheme.

[0231] The life-cycle cost model is as follows:

[0232]

[0233] Where C0 is the initial construction cost, and Cm j For the cost of the jth maintenance, Cu j Let t be the user delay cost for the j-th time, r be the discount rate, and t be the cost of delay for the user. j The time of the j-th maintenance is when it occurs;

[0234] (7.1) Cost parameters and discount rate values:

[0235] This embodiment uses the discount rate:

[0236] r=5%

[0237] The initial construction cost is:

[0238] Option I: C0 = 1 million yuan / km

[0239] Option II: C0 = 1.12 million yuan / km

[0240] Option III: C0 = 890,000 yuan / km;

[0241] The cost parameters for each maintenance session are as follows:

[0242] First maintenance:

[0243] C m1 =120,000 yuan / km, C u1 =50,000 yuan / km

[0244] C m1 +C u1 =170,000 yuan / km

[0245] Second maintenance:

[0246] C m2 =170,000 yuan / km, C u2 =60,000 yuan / km

[0247] C m2 +C u2 =230,000 yuan / km

[0248] • Third maintenance (same as the second maintenance in terms of engineering measures and traffic disruption, and its cost parameters use the same values ​​as the second maintenance):

[0249] C m3 =170,000 yuan / km, C u3 =60,000 yuan / km

[0250] C m3 +C u3 =230,000 yuan / km

[0251] (7.3) Maintenance strategies for the three schemes

[0252] In this embodiment, the maintenance time arrangements for the three schemes are as follows:

[0253] Option I: First maintenance in the 8th year, second maintenance in the 12th year;

[0254] Option II: Maintenance only required in the 12th year;

[0255] • Option III: First maintenance in the 8th year, followed by continuous maintenance in the 11th and 13th years.

[0256] (7.4) LCC calculation results for the three schemes:

[0257] Option I:

[0258]

[0259] Option II:

[0260]

[0261] Option III:

[0262]

[0263] (8) Results of material-structure joint optimization design

[0264] (8.1) Outer layer optimization (aiming at minimizing LCC)

[0265] In the candidate structure-material scheme set, the combination of material type and structural layer thickness corresponding to the minimum LCC value is taken as the outer layer optimization result. According to the calculation result of step (7), scheme II has the minimum LCC, so scheme II is determined to be the optimal structure-material scheme obtained by outer layer optimization.

[0266] (8.2) Inner layer verification (unified performance boundary function constraints)

[0267] For scheme II obtained from outer layer optimization, recalculate its fatigue utilization rate U. f Permanent deformation utilization rate Ur, low-temperature cracking utilization rate U CI And the unified performance boundary function F.

[0268]

[0269]

[0270]

[0271]

[0272] The results show that Scheme II meets the following requirements: that is, the scheme meets multiple performance requirements such as fatigue, rutting and low temperature cracking during the design life.

[0273] Therefore, under the premise of meeting the unified performance constraints, and taking into account the principle of minimizing the total life cycle cost, Scheme II was finally determined as the optimal structure-material integrated design scheme for this embodiment.

[0274] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A material-structure integrated long-life asphalt pavement design method based on performance range inversion, characterized in that, Includes the following steps: (1) Engineering input and preliminary structural selection Obtain the road grade, design service life, traffic load grade, and cumulative number of standard axle load applications N within the design life. design ; Collect environmental temperature data for the project area over the past 10 years to determine the representative temperature range to be used; Obtain the bearing capacity indicators of the subgrade, including the resilient modulus of the subgrade, the pavement surface layer structure, and the thickness of each structural layer; (2) Structural response analysis and calculation of three types of failure indices Under the structural system and environmental conditions set in step (1), the key mechanical responses, including the tensile strain ε at the bottom of the i-th layer, are calculated based on the multilayer elastic system theory program. t,i and the vertical compressive stress σ at the top of the i-th layer z,i And calculate the fatigue life N of the i-th layer respectively. f,i The permanent deformation R of the i-th layer structure a,i Low-temperature cracking index (CI) of asphalt surface layer; (3) Construct three types of failure utilization models The fatigue life, permanent deformation, and low-temperature cracking indices are dimensionless and defined as follows: Fatigue failure utilization rate: ;where N f,i Let be the fatigue life of the i-th layer; Permanent deformation failure utilization rate: , where R limit The allowable permanent deformation is determined according to the specifications, and n is the number of structural layers; Low-temperature cracking failure utilization rate: CI limit The permissible low-temperature cracking index is determined according to the specifications; (4) Construct a unified performance boundary function Based on the three types of utilization rates obtained in step (3), a unified performance boundary function F is constructed: ; (5) Material property range inversion With the thickness of each structural layer and N fixed design Under the condition of F≤0.8, the material performance parameters in the three types of failure utilization models in step (3) are taken as unknowns, and their reasonable engineering range is taken as the initial domain to obtain the material performance parameter range that meets the constraint conditions. (6) Screening of material property database The material performance parameter range obtained in step (5) is compared with the material performance database item by item, and the set of all material types that meet the range conditions, Candidate_i, is selected. (7) Establish a life-cycle cost model (LCC) Where C0 is the initial construction cost, and Cm j For the cost of the jth maintenance, Cu j Let t be the user delay cost for the j-th time, r be the discount rate, and t be the cost of delay for the user. j The time of the j-th maintenance is when it occurs; (8) Material-structure joint optimization design ①Outer layer optimization Select a material type from Candidate_i, calculate the corresponding LCC value based on the material type and the structural layer thickness, and use the material type and structural layer thickness corresponding to the minimum LCC value as the structure-material scheme; ②Inner layer verification Recalculate U based on the structure-material scheme obtained from the outer layer optimization. f U r U CI The unified performance boundary function F is used. If F ≤ 0.8, the scheme meets the life requirement and enters the candidate set; if F > 0.8, the structural layer thickness, material type or corresponding performance parameter range is adjusted until F ≤ 0.8 is met.

2. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion as described in claim 1, characterized in that, The road surface structure layer mentioned in step (1) includes a top layer, a middle layer, and a bottom layer.

3. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion as described in claim 1, characterized in that, The fatigue life N of the i-th layer mentioned in step (2) f,i The calculation formula is: , In the formula, β—target reliability index; k a —Adjustment coefficient for seasonally frozen soil areas; k b,i — Fatigue loading mode coefficient of the i-th asphalt mixture; k T1 —Temperature adjustment factor; ε t,i —Tensile strain at the bottom of the i-th layer of the asphalt mixture; E ′′ i —The dynamic compression modulus of the i-th asphalt mixture at 20°C; VFA i —Asphalt saturation of the i-th asphalt mixture.

4. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion as described in claim 1, characterized in that, The permanent deformation R of the i-th layer structure mentioned in step (2) a,i The calculation formula is: , In the formula, k Ri —Comprehensive correction factor; T pef —Equivalent temperature of permanent deformation of asphalt mixture layer; σ z,i —Vertical compressive stress at the top of the i-th layer of the asphalt mixture; N e3 —The cumulative number of times the equivalent design axle load is applied on the design lane within the design service life or from the opening to the first rut repair; h i —Thickness of the i-th layer; h0—thickness of the rutting test specimen; R 0,i —The permanent deformation of the i-th layer of asphalt mixture under rutting test at a test temperature of 60°C, a pressure of 0.7MPa, and 2520 loading cycles.

5. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion according to claim 1, characterized in that, The formula for calculating the low-temperature cracking index CI of the asphalt pavement in step (2) is as follows: , In the formula, S t Creep stiffness of surface asphalt flexural beam under 180s loading in rheological test at -10°C; b—Subgrade type parameter; T—Road surface low-temperature design temperature, which is the average of the lowest temperatures over 10 consecutive years; h a —Thickness of asphalt binder layer.

6. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion according to claim 1, characterized in that, The material performance parameters mentioned in step (5) include fatigue parameters, permanent deformation parameters, and low-temperature performance parameters.

7. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion as described in claim 1, characterized in that, The material performance parameter range mentioned in step (5) includes: The dynamic compression modulus range of the i-th asphalt mixture [E] ′′ i_min E ′′ i_max ]; The permanent deformation range of the i-th asphalt mixture [R] 0_i_min R 0_i_max ]; Surface layer asphalt creep stiffness range [S] t-min S t-max ].

8. The integrated material and structure design method for long-life asphalt pavement based on performance range inversion according to claim 1, characterized in that, In step (6), the material type is asphalt material, which includes at least one of aggregate, mineral powder, and fiber.

9. The application of the material structure integrated long-life asphalt pavement design method based on performance range inversion as described in any one of claims 1-8 in asphalt pavement structure design.

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