A method for predicting fatigue life of asphalt mixture layer of asphalt pavement

Abstract

The application discloses a kind of asphalt pavement asphalt mixture layer fatigue life prediction method, belong to data processing technical field, including preparation asphalt pavement structure fatigue life calculation layer asphalt mixture sample;Using beam four-point bending testing machine to carry out bending fatigue test to asphalt mixture, test the fatigue life of asphalt mixture under different test temperatures and strain levels, in combination with fatigue life test results, take the average of each test temperature and strain level combination, deduce fatigue life prediction model based on different each type asphalt mixture;According to the parameters of fatigue life prediction model based on different types of asphalt mixture, determine asphalt mixture layer fatigue cracking life model.The application constructs the fatigue life prediction model of pavement structure asphalt layer based on different types of asphalt mixture, and can realize the fatigue life prediction of asphalt pavement asphalt mixture layer for more than 30 years, is favorable for the accurate design and maintenance of long-life asphalt pavement structure.

Description

Technical Field

[0001] This invention discloses a method for predicting the fatigue life of asphalt mixture layers in asphalt pavement, belonging to the field of data processing technology. Background Technology

[0002] Fatigue cracking of asphalt pavement layers is one of the main forms of structural damage to asphalt pavements. The current Chinese highway asphalt pavement design specification (JTG D50-2017) provides a fatigue cracking life prediction model for asphalt pavement layers. This model has two main problems: First, the fatigue model in the specification is based on experimental research of matrix asphalt mixtures, and is not applicable to the specific asphalt mixtures commonly used in highways; it is not a fatigue model specifically designed for particular asphalt mixtures. Second, the design service life of asphalt pavement structures in my country is generally 15 years. The current highway asphalt pavement design specification (JTG D50-2017) asphalt layer fatigue prediction model is only applicable to conventional asphalt pavements (design service life of 15 years) and cannot achieve the design of long-life asphalt pavements (design service life exceeding 30 years). Summary of the Invention

[0003] The purpose of this invention is to provide a method for predicting the fatigue life of asphalt mixture layers in asphalt pavements, so as to solve the problem that the fatigue cracking life prediction model of asphalt mixture layers is not applicable and cannot perform long-life prediction in the prior art.

[0004] A method for predicting the fatigue life of asphalt mixture layers in asphalt pavement includes:

[0005] S1. Obtain the asphalt pavement structure to be studied and prepare asphalt mixture samples for fatigue life calculation layer;

[0006] S2. Using a small beam four-point bending tester, bending fatigue tests were conducted on specific asphalt mixtures to test the fatigue life of the asphalt mixtures under different test temperatures and strain levels.

[0007] S3. Combining the fatigue life test results in S2, take the average value of each test temperature and strain level combination, and derive the fatigue life prediction model based on different types of asphalt mixtures.

[0008] S4. Based on the parameters of fatigue life prediction models for different types of asphalt mixtures, determine the fatigue cracking life model for asphalt mixture layers in structural layers, which is used for fatigue life prediction of asphalt layers in asphalt pavement structures.

[0009] S5. Obtain road traffic load parameters using an on-site dynamic weighing system, and determine the cumulative equivalent axle load application times N of the design lane within the design service life by referring to Appendix A of the "Specifications for Design of Highway Asphalt Pavement" JTGD50-2017. e ;

[0010] S6. Determine whether the measured cumulative number of traffic axle load applications is less than the fatigue cracking life N of the asphalt layer. f .

[0011] In S2, when conducting flexural fatigue tests on asphalt mixtures, 27 specimens were used. Nine specimens were set for each of the three test temperatures: 10°C, 20°C, and 30°C. The nine specimens at each test temperature were divided into three strain levels on average, and the test frequency was 10 Hz.

[0012] In S2, the strain level satisfies the following condition:

[0013] (1) Ensure that the fatigue life of all specimens exceeds 10 years. 4 The next loop;

[0014] (2) At each test temperature, 22% of the specimens had a fatigue life exceeding 10. 6 Second-rate.

[0015] In S3, fatigue life prediction models based on different types of asphalt mixtures are used:

[0016]

[0017] In the formula, N lab E represents the fatigue life (times) at which the asphalt mixture flexural fatigue test specimen fails. lab The flexural stiffness modulus (MPa) at the current test frequency and temperature is determined by the master curve of the flexural stiffness modulus, ε. lab ε represents the strain (με) from the indoor bending fatigue test, and k1 to k5 are fitting parameters.

[0018] In S3, a four-point bending tester for small beams is used to conduct bending stiffness modulus tests on different types of asphalt mixtures. The bending stiffness modulus of asphalt mixtures under different test temperatures and loading frequencies is tested. Based on the bending stiffness modulus test results, the average value of each test temperature and test frequency combination is taken, and the main curve of bending stiffness modulus is established according to the time-temperature equivalence principle.

[0019] In S4, the fatigue cracking life model for asphalt mixture layers is as follows:

[0020]

[0021] In the formula, N f E represents the fatigue life (times) of an asphalt mixture layer. d The design flexural stiffness modulus (MPa) is given by ε, the tensile strain at the bottom of the asphalt mixture layer (με), k1~k5 are the fitting parameters determined by the fatigue life prediction model of the asphalt mixture, and β is the fatigue cracking reliability factor of the asphalt mixture layer, which is determined by the highway grade and traffic volume.

[0022] In S4, the flexural strain ε at the bottom of the asphalt mixture layer is determined by the pavement structure mechanics software. Based on the proposed asphalt pavement structure, the design flexural modulus of the asphalt mixture in each asphalt layer is input into the mechanical calculation software BISAR3.0 to obtain the calculated value of the strain at the bottom of the asphalt mixture layer.

[0023] Compared with existing technologies, this invention constructs a fatigue life prediction model for asphalt layers of pavement structures based on different types of asphalt mixtures, and can predict the fatigue life of asphalt mixture layers of asphalt pavement for more than 30 years, which is beneficial to the precise design and maintenance of asphalt pavement structures. Attached Figure Description

[0024] Figure 1 It is the master curve of flexural stiffness modulus of SMA-13, AC-20, AC-25 and LSPM-25 asphalt mixtures at a reference temperature of 20℃. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] A method for predicting the fatigue life of asphalt mixture layers in asphalt pavement includes:

[0027] S1. Obtain the asphalt pavement structure to be studied and prepare asphalt mixture samples for fatigue life calculation layer;

[0028] S2. A four-point bending tester was used to conduct bending fatigue tests on asphalt mixtures to test the fatigue life of specific asphalt mixtures under different test temperatures and strain levels.

[0029] S3. Combining the fatigue life test results in S2, take the average value of each test temperature and strain level combination, and derive the fatigue life prediction model based on different types of asphalt mixtures.

[0030] S4. Based on the parameters of fatigue life prediction models for different types of asphalt mixtures, determine the fatigue cracking life model for asphalt mixture layers in structural layers, which is used for fatigue life prediction of asphalt layers in asphalt pavement structures.

[0031] S5. Obtain road traffic load parameters using the on-site dynamic weighing system, and determine the cumulative equivalent axle load application times Ne for the design lane within the design service life by referring to Appendix A of the "Specifications for Design of Highway Asphalt Pavement" JTGD50-2017.

[0032] S6. Determine whether the measured cumulative number of traffic axle load applications is less than the fatigue cracking life Nf of the asphalt layer.

[0033] In S2, when conducting flexural fatigue tests on asphalt mixtures, 27 specimens were used. Nine specimens were set for each of the three test temperatures: 10°C, 20°C, and 30°C. The nine specimens at each test temperature were divided into three strain levels on average, and the test frequency was 10 Hz.

[0034] In S2, the strain level satisfies the following condition:

[0035] (1) Ensure that the fatigue life of all specimens exceeds 10 years. 4 The next loop;

[0036] (2) At each test temperature, 22% of the specimens had a fatigue life exceeding 10. 6 Second-rate.

[0037] In S3, the fatigue life prediction model based on different types of asphalt mixtures is as follows:

[0038]

[0039] In the formula, N lab E represents the fatigue life (times) at which the asphalt mixture flexural fatigue test specimen fails. lab The flexural stiffness modulus (MPa) at the current test frequency and temperature is determined by the master curve of the flexural stiffness modulus, ε. lab ε represents the strain (με) from the indoor bending fatigue test, and k1 to k5 are fitting parameters.

[0040] In S3, a four-point bending tester for small beams is used to conduct bending stiffness modulus tests on different types of asphalt mixtures. The bending stiffness modulus of asphalt mixtures under different test temperatures and loading frequencies is tested. Based on the bending stiffness modulus test results, the average value of each test temperature and test frequency combination is taken, and the main curve of bending stiffness modulus is established according to the time-temperature equivalence principle.

[0041] In S4, the fatigue cracking life model for asphalt mixture layers is as follows:

[0042]

[0043] In the formula, N f E represents the fatigue life (times) of an asphalt mixture layer. d To design the flexural stiffness modulus (MPa), ε is the tensile strain at the bottom of the asphalt mixture layer (με), k1~k5 are the fitting parameters determined by the fatigue life prediction model of asphalt mixture, and β is the fatigue cracking reliability factor of asphalt mixture layer, which is determined by the highway grade and traffic volume, as shown in Table 1.

[0044] Table 1. Reliability factor (β) for fatigue cracking of asphalt layer

[0045]

[0046] In S4, the flexural strain ε at the bottom of the asphalt mixture layer is determined by the pavement structure mechanics software. Based on the proposed asphalt pavement structure, the design flexural modulus of the asphalt mixture in each asphalt layer is input into the mechanical calculation software BISAR3.0 to obtain the calculated value of the strain at the bottom of the asphalt mixture layer.

[0047] The calculation of flexural stiffness modulus includes:

[0048] B1. Obtain the measured temperature field data of the asphalt pavement to be studied through the pavement structure temperature measurement device, and use the least squares method to obtain the calculation model of the temperature at different depths of the pavement, and determine the equivalent temperature of each structural layer of the asphalt surface layer as the design temperature.

[0049] B2. Obtain the speed of heavy vehicles in each lane of the highway on the asphalt pavement to be studied through the traffic axle load dynamic testing system, select the representative speed value as the design speed of heavy vehicles, and determine the loading frequency of vehicle load on the target structural layer of asphalt pavement at the design speed.

[0050] B3. Based on the master curve of flexural stiffness modulus, determine the calculation model of flexural stiffness modulus of asphalt mixture under different temperatures and loading frequencies;

[0051] B4 inputs the values ​​into the calculation model of the flexural stiffness modulus of asphalt mixtures under different temperatures and loading frequencies to obtain the experimental void ratio modulus.

[0052] B5. Adjust the test void ratio modulus to the service void ratio modulus to complete the prediction of the flexural stiffness modulus of asphalt pavement.

[0053] The calculation model for temperature at different depths of the road surface is as follows:

[0054] T′=α5×z 5 +α4×z 4 +α3×z 3 +α2×z 2 +α1×z+α0

[0055] In the formula, T′ is the actual measured temperature (°C), α5, α4, α3, α2, α1, and α0 are model parameters, z is the thickness of the asphalt surface layer (cm), and the bottom of the asphalt layer is taken as the starting point.

[0056] The equivalent temperature of each structural layer of the asphalt pavement is determined as the design temperature using the following formula:

[0057]

[0058] In the formula, T di h represents the equivalent temperature (°C) of each structural layer of the asphalt surface course. i Let be the thickness (cm) of each structural layer of the asphalt pavement, and i be the number of structural layers of the asphalt pavement, i = 1, 2, 3...n.

[0059] The loading frequency of vehicle load on the target structural layer of asphalt pavement at the design speed shall be determined according to the following formula:

[0060]

[0061] Among them, f d The loading frequency (Hz) of the vehicle load on the target structural layer of the asphalt pavement at the design speed is given by h, which is the depth of the road surface downwards (cm), and v is the design speed of the loaded vehicle (km / h).

[0062] The calculation model E for the flexural stiffness modulus of asphalt mixtures under different temperatures and loading frequencies is as follows:

[0063]

[0064] Where: α, β, f c m, k, c1, c2 are model parameters, and T ref The reference temperature is 20℃.

[0065] Adjust the porosity modulus of asphalt mixtures in laboratory tests to the predicted modulus using the following formula:

[0066]

[0067] The loading frequency includes at least eight frequencies between 0.1 Hz and 25 Hz.

[0068] The test temperatures include at least three of the following: 5°C, 10°C, 20°C, 30°C, 40°C, and 50°C.

[0069] Taking a newly built expressway in Jinan, Shandong Province as an example, the fatigue life of the asphalt mixture layer of the expressway pavement is determined using the method proposed in this invention.

[0070] The pavement structure is a composite base asphalt concrete pavement structure, consisting of an asphalt layer, a flexible base course, a base course, and a subgrade from top to bottom. The asphalt layer is 180mm thick and is further divided into a top layer, an intermediate layer, and a bottom layer. The top layer is 40mm thick and made of modified SMA13; the intermediate layer is 60mm thick and made of modified AC20; and the bottom layer is 80mm thick and made of modified AC25. The flexible base course is a 100mm thick large-particle-size permeable modified asphalt mixture LSPM25, and the base course consists of three 180mm layers of cement-stabilized crushed stone. The target reliability of the pavement structure is 97%.

[0071] Asphalt mixture samples were prepared. Typical service void ratios for asphalt mixtures were: 5.0% for AC-7, AC-10, and AC-13; 7% for AC-16, AC-20, and AC-25; 4.0% for SMA-10, SMA-13, and SMA-14; 17.0% for LSPM-25; 3.5% for EME-14; and 4.5% for EME-20. In this invention, the test void ratios selected were 3% for SMA-13, 5.0% for AC-20, 5.0% for AC-25, and 15.0% for LSPM-25.

[0072] The test temperatures were set at 5, 10, 20, 30, and 40℃, and the test frequencies at each temperature were 0.1, 0.2, 0.5, 1, 5, 10, 20, and 25 Hz. The test results are shown in Table 2. The master curves for the flexural stiffness modulus of the asphalt mixture in each structural layer of the asphalt layer were established, as shown in Table 2. Figure 1 .

[0073] Table 2 Results of Bending Stiffness Modulus Test

[0074]

[0075]

[0076] Based on the master curve of the flexural stiffness modulus of asphalt mixtures, the calculation model of the flexural stiffness modulus of asphalt mixtures in each structural layer of the asphalt layer under different temperatures and loading frequencies is obtained, as shown below:

[0077]

[0078] Where: E1 is the flexural stiffness modulus of the upper SMA-13 ​​layer (MPa); T1 is the thickness equivalent temperature of the upper layer; f1 is the loading frequency of the upper layer (Hz);

[0079]

[0080] Where: E2 is the flexural stiffness modulus (MPa) of the middle layer AC-20; T2 is the thickness equivalent temperature of the top layer; f2 is the loading frequency (Hz) of the top layer;

[0081]

[0082] Where: E3 is the flexural stiffness modulus of the lower layer AC-25 (MPa); T3 is the thickness equivalent temperature of the lower layer; f3 is the loading frequency of the lower layer (Hz);

[0083]

[0084] Where: E4 is the flexural stiffness modulus (MPa) of the flexible base layer LSPM-25; T4 is the equivalent temperature of the flexible base layer thickness; f4 is the loading frequency (Hz) of the underlying layer;

[0085] The equivalent temperatures of each structural layer of the asphalt pavement are determined as follows:

[0086]

[0087] Wherein: T d1 The equivalent temperature of the upper SMA-13 ​​layer is given by z, and the thickness of the asphalt surface layer is given by z. The origin is set at the bottom of the asphalt layer (cm).

[0088]

[0089] Wherein: T d2 The equivalent temperature of the AC-20 intermediate layer is given by z, and the thickness of the asphalt surface layer is given by z. The origin is set at the bottom of the asphalt layer (cm).

[0090]

[0091] Wherein: T d3 Let z be the equivalent temperature of the lower AC-25 layer, z be the coordinate of the asphalt surface layer thickness, and the origin be the bottom of the asphalt layer (cm).

[0092]

[0093] Wherein: T d4 The equivalent temperature of the flexible base layer LSPM-25 is given by z, which is the coordinate of the asphalt surface layer thickness. The origin is set at the bottom of the asphalt layer (cm).

[0094] The calculated equivalent temperatures of the thicknesses of the top, middle, bottom, and flexible base layers of the asphalt pavement structure are 50.5℃, 47.5℃, 43.3℃, ​​and 35.2℃, respectively.

[0095] By setting up a dynamic weighing system on the asphalt pavement surface and obtaining the design speed of a heavy vehicle at 100 km / h, the loading frequencies of the asphalt pavement structure's top layer, middle layer, bottom layer, and flexible base layer were found to be 12 Hz, 10 Hz, 7 Hz, and 6.5 Hz, respectively.

[0096] Based on the calculation model of the flexural stiffness modulus of asphalt mixture, the flexural stiffness moduli of SMA-13, AC-20, AC-25 and LSPM-25 under the design temperature and heavy vehicle design speed are determined to be 1287MPa, 2662MPa, 2272MPa and 2307MPa, respectively.

[0097] Adjusting the test porosity modulus of SMA-13, AC-20, AC-25, and LSPM-25 to their service porosity modulus, the test porosities of SMA-13, AC-20, AC-25, and LSPM-25 are 3%, 5.0%, 5.0%, and 15%, respectively. The service porosities in engineering implementation are 4.0%, 7%, 7%, and 17%, respectively. Therefore, the service porosity moduli of SMA-13, AC-20, AC-25, and LSPM-25 are 1216 MPa, 2329 MPa, 1988 MPa, and 1538 MPa, respectively.

[0098] LSPM-25 asphalt mixture was prepared and subjected to flexural fatigue tests. A total of 27 specimens were tested at three different temperatures: 10°C, 20°C, and 30°C, with nine specimens at each temperature. The nine specimens at each temperature were averaged across three strain levels, and the test frequency was 10 Hz. The test results are shown in Table 3.

[0099] Table 3 Results of Bending Fatigue Tests on Asphalt Mixtures

[0100] Specimen Temperature (T)(°C) <![CDATA[Strain amplitude (ε lab )]]> <![CDATA[Number of fatigue failures (N lab )]]> 1 10 130 1,127,940 2 10 130 2,199,483 3 10 130 1,240,735 4 10 180 281,429 5 10 180 201,021 6 10 180 408,072 7 10 280 57,992 8 10 280 19,330 9 10 280 15,465 10 20 170 504,219 11 20 170 1,232,537 12 20 170 784,342 13 20 200 236,754 14 20 200 184,668 15 20 200 497,184 16 20 300 27,607 17 20 300 138,034 18 20 300 49,692 19 30 200 1,945,031 20 30 200 1,264,271 21 30 200 4,862,575 22 30 380 64,794 23 30 380 143,842 24 30 380 90,711 25 30 450 34,380 26 30 450 26,446 27 30 450 50,248

[0101] Based on the experimental results in the table, the fatigue prediction model for LSPM-25 mixture is as follows:

[0102]

[0103] The fatigue life prediction model for asphalt pavement structures is as follows:

[0104]

[0105] Based on the highway grade and the target reliability of the pavement structure, the fatigue cracking reliability factor of the asphalt mixture layer is determined to be 9.0.

[0106] The flexural tensile strain ε at the bottom of the asphalt mixture layer of this pavement structure was calculated to be 29.4 με using the pavement structure mechanics software BISAR3.0. Therefore, the fatigue life of the asphalt layer of the pavement structure is:

[0107]

[0108] Road traffic load parameters were obtained using an on-site dynamic weighing system. Referring to Appendix A of the "Specifications for Design of Highway Asphalt Pavement" JTGD50-2017, the cumulative equivalent axle load application times Ne for the design lanes within the 15-year and 30-year design service life were determined to be 4.2 × 10⁻⁶. 7 and 1.21×10 8 All of them are less than the fatigue life of the asphalt layer in the asphalt pavement structure.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the fatigue life of asphalt mixture layers in asphalt pavement, characterized in that, include: S1. Obtain the asphalt pavement structure to be studied and prepare asphalt mixture samples for fatigue life calculation layer; S2. A four-point bending tester was used to conduct bending fatigue tests on asphalt mixtures to test the fatigue life of asphalt mixtures under different test temperatures and strain levels. S3. Combining the fatigue life test results in S2, take the average value of each test temperature and strain level combination, and derive the fatigue life prediction model based on different types of asphalt mixtures. S4. Based on the parameters of fatigue life prediction models for different types of asphalt mixtures, determine the fatigue cracking life model for asphalt mixture layers in structural layers, which is used for fatigue life prediction of asphalt layers in asphalt pavement structures. S5. Obtain road traffic load parameters using an on-site dynamic weighing system to determine the cumulative equivalent axle load application times for the design lane within its design service life. ; S6. Determine whether the measured cumulative number of traffic axle load applications is less than the fatigue cracking life of the asphalt layer. ; In S3, the fatigue life prediction model based on different types of asphalt mixtures is as follows: ； In the formula, The fatigue life of the asphalt mixture specimen at failure during flexural fatigue testing is expressed in cycles. This represents the flexural stiffness modulus at the current test frequency and temperature, in MPa, determined by the master curve of flexural stiffness modulus. The strain measured in indoor bending fatigue tests is expressed in units of 1. , ~ These are the fitting parameters; The fatigue cracking life model for asphalt mixture layers is as follows: ； In the formula, The fatigue life of an asphalt mixture layer is expressed in cycles. To design the flexural stiffness modulus, the unit is MPa. The tensile strain at the bottom of the asphalt mixture layer is expressed in με. ~ Fitting parameters determined for the fatigue life prediction model of asphalt mixtures. The fatigue cracking reliability factor of asphalt mixture layers is determined by the highway grade and traffic volume. In S4, the flexural strain ε at the bottom of the asphalt mixture layer is determined by the pavement structure mechanics software. Based on the proposed asphalt pavement structure, the design flexural modulus of the asphalt mixture in each asphalt layer is input into the mechanical calculation software BISAR3.0 to obtain the calculated value of the strain at the bottom of the asphalt mixture layer. The calculation of flexural stiffness modulus includes: B1. Obtain the measured temperature field data of the asphalt pavement to be studied through the pavement structure temperature measurement device, and use the least squares method to obtain the calculation model of the temperature at different depths of the pavement, and determine the equivalent temperature of each structural layer of the asphalt surface layer as the design temperature. B2. Obtain the speed of heavy vehicles in each lane of the highway on the asphalt pavement to be studied through the traffic axle load dynamic testing system, select the representative speed value as the design speed of heavy vehicles, and determine the loading frequency of vehicle load on the target structural layer of asphalt pavement at the design speed. B3. Based on the master curve of flexural stiffness modulus, determine the calculation model of flexural stiffness modulus of asphalt mixture under different temperatures and loading frequencies; The calculation model for temperature at different depths of the road surface is as follows: ； In the formula, The temperature was measured on-site, and the unit is... , , , , , , Here are the model parameters, z is the thickness of the asphalt surface layer in cm, and the starting point is the bottom of the asphalt layer. The equivalent temperature of each structural layer of the asphalt pavement is determined as the design temperature using the following formula: ； In the formula, The equivalent temperature of each structural layer of the asphalt surface layer, in units of... , The thickness of each structural layer of the asphalt surface layer is given in cm. The number of asphalt pavement layers. =1, 2, 3...n; The loading frequency of vehicle load on the target structural layer of asphalt pavement at the design speed shall be determined according to the following formula: ； in, The loading frequency of vehicle load on the target structural layer of asphalt pavement at the design speed is expressed in Hz, h is the depth of the road surface downwards in cm, and v is the design speed of the heavy vehicle in km / h. Calculation model of flexural stiffness modulus of asphalt mixture under different temperatures and loading frequencies for: ； in: , , , , , , For model parameters, For reference temperature, the value is 20. .

2. The method for predicting the fatigue life of asphalt mixture layers in asphalt pavement according to claim 1, characterized in that, In S2, when conducting flexural fatigue tests on asphalt mixtures, 27 samples were used, and three test temperatures were applied. 20 and 30 Nine specimens were set up for each test temperature, and the nine specimens for each test temperature were divided into three strain levels on average. The test frequency was 10 Hz.

3. The method for predicting the fatigue life of asphalt mixture layers in asphalt pavement according to claim 2, characterized in that, In S2, the strain test level used meets the following conditions: The fatigue life of all specimens exceeded Second-rate; At each test temperature, 22% of the specimens had a fatigue life exceeding [a certain value]. Second-rate.

4. The method for predicting the fatigue life of asphalt mixture layers in asphalt pavement according to claim 3, characterized in that, In S3, a four-point bending tester for small beams is used to conduct bending stiffness modulus tests on different types of asphalt mixtures. The bending stiffness modulus of asphalt mixtures under different test temperatures and loading frequencies is tested. Based on the bending stiffness modulus test results, the average value of each test temperature and test frequency combination is taken, and the main curve of bending stiffness modulus is established according to the time-temperature equivalence principle.

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