A method for estimating the remaining life of cement-stabilized macadam base of asphalt pavement based on modulus

Abstract

The present invention discloses a modulus-based method for estimating the remaining life of a cement-stabilized macadam base layer of an asphalt pavement. The method first obtains the thickness of each structural layer in the asphalt pavement corresponding to the cement-stabilized macadam base layer for which life estimation is required, as well as the initial structural modulus of each structural layer; obtains the flexural tensile strength of the cement-stabilized macadam base layer material; obtains the current structural modulus of the cement-stabilized macadam base layer at the wheel track of the asphalt pavement; determines the number of single-lane equivalent design axle loads acting on the asphalt pavement per year; determines the number of freeze-thaw cycles, freezing temperature, and freeze-thaw humidity of the cement-stabilized macadam base layer per year; and then calculates the remaining life and remaining service life of the cement-stabilized macadam base layer by establishing an attenuation equation for the modulus of the cement-stabilized macadam material under freeze-thaw cycles and an attenuation equation for the structural modulus of the cement-stabilized macadam under traffic loads. The present invention, based on a computer, can quantitatively estimate the remaining life and service life of the cement-stabilized macadam base layer, providing a basis for the timing and strategy of pavement maintenance.

Description

Technical Field

[0001] The invention relates to the technical field of computer-aided design, and in particular to a method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on a modulus. Background Art

[0002] The main structural form of high-grade highway pavement is an asphalt concrete surface layer paved on a cement-stabilized gravel base.

[0003] The cement-stabilized gravel base, as the primary load-bearing structure of a road, has a lifespan that directly impacts its overall performance. Therefore, estimating the remaining life of the existing cement-stabilized gravel base is crucial when evaluating the performance of older roads.

[0004] However, research on estimating the remaining life of existing cement-stabilized gravel bases has not received sufficient attention. Currently, in terms of performance evaluation of old roads, the main approach is to evaluate the overall condition of the road surface and the bearing capacity of the pavement structure. The main indicators for evaluating the road surface condition include: Pavement Condition Index (PCI), Pavement Quality Index (RQI), Pavement Rutting Depth Index (RDI), Pavement Skid Resistance Index (SRI), etc. The evaluation index for the bearing capacity of the pavement structure is: Pavement Structure Strength Index (PSSI). The above indicators can characterize the damage of the road surface or the overall performance of the road, but cannot characterize the remaining life of the cement-stabilized gravel base. Therefore, in actual projects, designers can only qualitatively analyze the remaining life of the cement-stabilized gravel base through empirical judgment, excavation verification, etc., but cannot conduct an objective and quantitative analysis of the remaining life of the cement-stabilized gravel base, which is obviously subjective and arbitrary.

[0005] Furthermore, in seasonally frozen areas, cement-stabilized crushed stone bases are primarily subjected to traffic loads and freeze-thaw cycles. Traffic loads can cause cracking in the base, leading to pavement cracking, while freeze-thaw cycles can loosen the base. Both of these effects can degrade the performance of cement-stabilized crushed stone bases and reduce their service life. Currently, the impact of these two effects on the lifespan of cement-stabilized crushed stone bases has not been fully considered when estimating the remaining lifespan of cement-stabilized crushed stone bases.

[0006] Therefore, how to achieve an objective and quantitative estimation of the remaining life of the cement-stabilized macadam base of an asphalt pavement has become a technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the present invention provides a modulus-based method for estimating the remaining life of a cement-stabilized macadam base layer of an asphalt pavement. The purpose of the present invention is to enable a rapid and efficient objective quantitative estimation of the remaining life of a cement-stabilized macadam base layer of an asphalt pavement, thereby laying the foundation for the evaluation of pavement structure performance and assisting in the formulation of pavement maintenance and repair decisions.

[0008] To achieve the above object, the present invention discloses a method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus, comprising the following steps:

[0009] Step 1: Obtain the thickness of each structural layer and the initial structural modulus of each structural layer in the asphalt pavement corresponding to the cement-stabilized crushed stone base for which remaining life estimation is required; wherein the initial structural modulus of the cement-stabilized crushed stone base is denoted as E0;

[0010] Obtaining the flexural tensile strength R of the cement-stabilized crushed stone base material;

[0011] Obtain the current structural modulus E of the cement-stabilized macadam base at the wheel track of the asphalt pavement D1 ;

[0012] Determine the number of times n the equivalent design axle load of a single lane acts on the asphalt pavement each year i ;

[0013] Determine the freeze-thaw frequency, freezing temperature and freeze-thaw humidity of the cement-stabilized crushed stone base layer in one year;

[0014] Step 2: Establish the attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles and the attenuation equation of the modulus of cement-stabilized crushed stone structure under traffic loads;

[0015] The attenuation equation of the modulus of cement-stabilized crushed stone material under the freeze-thaw cycle is as follows:

[0016]

[0017] Among them, E m is the material modulus after m freeze-thaw cycles, in MPa;

[0018] E C0 is the initial material modulus, in MPa;

[0019] t is the freezing temperature of the cement-stabilized crushed stone base, in °C;

[0020] ω is the moisture content of the cement-stabilized gravel base;

[0021] a1, b1, c1 are parameters;

[0022] The attenuation equation of the modulus of the cement-stabilized crushed stone structure under traffic load is as follows:

[0023]

[0024]

[0025]

[0026]

[0027] Wherein, N is the fatigue life of the cement stabilized crushed stone base, in times;

[0028] k a is the adjustment coefficient for seasonally frozen areas;

[0029] k T2 is the temperature adjustment coefficient;

[0030] R is the flexural tensile strength of the cement-stabilized crushed stone base material, in MPa;

[0031] σ is the maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer, in MPa;

[0032] k c is the on-site comprehensive correction coefficient;

[0033] h a 、h b are the thickness of the asphalt surface layer of the asphalt pavement and the thickness of the cement-stabilized macadam base layer respectively;

[0034] β is the target reliability indicator;

[0035] D is the amount of base layer damage;

[0036] n is the number of traffic load loading times, in times;

[0037] E D is the structural modulus of the cement-stabilized crushed stone base when the damage reaches D, in MPa;

[0038] E0 is the initial structural modulus of the cement-stabilized crushed stone base, in MPa;

[0039] a2 and b2 are parameters;

[0040] Step 3: Using multi-layer elastomer analysis software to establish a road structure calculation model for the asphalt pavement; wherein the traffic load adopts the BZZ-100 standard axle load, the thickness of each structural layer in the software adopts the thickness of the existing pavement structure layer, and the modulus of each structural layer adopts the initial structural modulus, and the maximum tensile stress σ at the bottom of the cement-stabilized crushed stone base layer is calculated;

[0041] Step 4: Calculate the fatigue life N of the cement-stabilized crushed stone base according to equations (2) and (3);

[0042] Step 5: The current structural modulus E of the cement stabilized gravel base D1As the structural modulus E of the cement stabilized crushed stone base when the damage amount reaches D D , together with the initial structural modulus E0 of the cement-stabilized crushed stone base, the current damage amount D1 of the base is calculated using formula (5);

[0043] Step 6: Based on Miner's law, design the number of axle load actions n according to the single lane equivalent in one year i , calculate the damage amount D2 of the cement-stabilized gravel base after one year of traffic load, the specific formula is as follows:

[0044] D2=D1+n i / N formula (6);

[0045] Step 7: Using the initial structural modulus E0 of the cement-stabilized gravel base and the damage amount D2 of the cement-stabilized gravel base after one year of traffic load, the structural modulus E0 of the cement-stabilized gravel base after one year of traffic load is obtained using formula (5). D2 ;

[0046] Step 8: Combine the structural modulus E of the cement stabilized gravel base after one year of traffic load D2 As well as the number of freeze-thaw cycles, freezing temperature and freeze-thaw humidity of the base layer in one year, the base modulus estimation method under freeze-thaw cycles is used to calculate the structural modulus E of the cement-stabilized crushed stone base layer after one year of freeze-thaw cycles. D3 ;

[0047] Step 9: Using the structural modulus E of the cement-stabilized gravel base after one year of freeze-thaw cycle D3 and the initial structural modulus E0 of the cement-stabilized crushed stone base, and the damage amount D3 of the cement-stabilized crushed stone base after one year of freeze-thaw cycle is calculated by formula (5);

[0048] Step 10: Repeat steps 6 to 9 to calculate the damage accumulation of the cement-stabilized gravel base under traffic load and freeze-thaw cycles until the damage amount D=1;

[0049] The sum of the times the cement-stabilized gravel base layer is subjected to the equivalent design axle load before the damage amount D reaches 1 is the remaining life of the active base layer; the sum of the calculated years is the remaining service life of the active base layer.

[0050] Preferably, the method for estimating the base modulus under freeze-thaw cycles in step 8 is as follows:

[0051] Step 8.1: Assume that the cement-stabilized crushed stone base material experiences m1 and m2 freeze-thaw cycles under two freeze-thaw temperature and humidity conditions in one year;

[0052] Each of the freeze-thaw temperature and humidity conditions refers to a combination of freezing temperature and freeze-thaw humidity, and the two freeze-thaw temperature and humidity conditions are a first combination condition including a first freezing temperature t1 and a first freeze-thaw humidity ω1, and a second combination condition including a second freezing temperature t2 and a second freeze-thaw humidity ω2;

[0053] Step 8.2: The structural modulus E of the cement-stabilized crushed stone base after one year of traffic load D2 Multiply by 2 and convert to material modulus E m The initial structural modulus E0 of the cement stabilized gravel base is multiplied by 2 and converted into the initial material modulus E C0 ;

[0054] Step 8.3: Calculate the material modulus E of the cement-stabilized gravel base after m1 freeze-thaw cycles under the first combination condition. m1 The specific process is as follows:

[0055] The material modulus E m , the initial material modulus E C0 , the first freezing temperature t1 and the first freeze-thaw humidity ω1 are substituted into formula (1) to calculate the material modulus E corresponding to the first combination condition. m The first equivalent freeze-thaw number p1;

[0056] Then the initial material modulus E C0 , the first freezing temperature t1, the first freeze-thaw humidity ω1 and p1+m1 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition. m1 ;

[0057] Step 8.4: Calculate the material modulus E of the cement-stabilized gravel base after m2 freeze-thaw cycles under the second combination condition. m2 The specific process is as follows:

[0058] The material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition is m1 , the initial material modulus E C0 , the second freezing temperature t2 and the second freeze-thaw humidity ω2 are substituted into formula (1) to calculate the corresponding E under the second combination condition m1 The second equivalent freeze-thaw number p2;

[0059] Then the initial material modulus E C0, the second freezing temperature t2, the second freeze-thaw humidity ω2 and p2+m2 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m2 freeze-thaw cycles under the second combination condition. m2 ;E m2 That is, the material modulus of the cement-stabilized crushed stone base after experiencing m1 and m2 freeze-thaw cycles under the two freeze-thaw temperature and humidity conditions;

[0060] Step 8.5, E m2 Multiply by 0.5 as the structural modulus of the cement-stabilized gravel base after experiencing m1 and m2 freeze-thaw cycles under the two freeze-thaw temperature and humidity conditions, that is, the structural modulus E of the cement-stabilized gravel base after one year of freeze-thaw cycle. D3 .

[0061] More preferably, if there are three or more freeze-thaw temperature and humidity conditions in step 8.1, step 8.4 is repeated to calculate the base structure modulus of the cement-stabilized gravel base after multiple freeze-thaw cycles under all the freeze-thaw temperature and humidity conditions.

[0062] Preferably, a1=-0.1297; b1=0.2511; c1=0.1432.

[0063] Preferably, a2=11.0446; b2=3.8362.

[0064] Beneficial effects of the present invention:

[0065] (1) The present invention comprehensively considers the effects of traffic load and freeze-thaw cycle on the life of the base layer, and can well model and estimate the modulus of the cement-stabilized crushed stone base layer;

[0066] (2) In terms of base layer life prediction, the present invention can quantitatively predict the remaining life and remaining service life of the existing cement-stabilized crushed stone base based on the modulus attenuation law, comprehensive traffic load and freeze-thaw cycle effects, and provide a basis for the timing and maintenance strategy of pavement maintenance;

[0067] (3) The present invention overcomes the subjectivity and arbitrariness in estimating the remaining life of cement-stabilized crushed stone base in actual engineering.

[0068] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 FIG. 1 shows an execution flow chart of an embodiment of the present invention.

[0070] Figure 2A schematic diagram showing the calculation of the base modulus under freeze-thaw cycles in one embodiment of the present invention is shown.

[0071] Figure 3 A comparison chart of measured data of the base material modulus and data calculated by the attenuation equation in one embodiment of the present invention is shown.

[0072] Figure 4 A comparison chart of measured data of the base structure modulus and data calculated by the attenuation equation in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0073] Example 1

[0074] like Figure 1 As shown in FIG, the method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus includes the following steps:

[0075] Step 1: Obtain the thickness of each structural layer and the initial structural modulus of each structural layer in the asphalt pavement corresponding to the cement-stabilized crushed stone base for which remaining life estimation is required; wherein the initial structural modulus of the cement-stabilized crushed stone base is denoted as E0;

[0076] Obtain the flexural tensile strength R of the cement-stabilized crushed stone base material;

[0077] Get the current structural modulus E of the cement-stabilized crushed stone base at the wheel track of the asphalt pavement D1 ;

[0078] Determine the number of times n the equivalent design axle load acts on the asphalt pavement per year i ;

[0079] Determine the freeze-thaw frequency, freezing temperature and freeze-thaw humidity of the cement-stabilized crushed stone base in a year;

[0080] Step 2: Establish the attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles and the attenuation equation of the modulus of cement-stabilized crushed stone structure under traffic loads;

[0081] The attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles is as follows:

[0082]

[0083] Among them, E m is the material modulus after m freeze-thaw cycles, in MPa;

[0084] E C0 is the initial material modulus, in MPa;

[0085] t is the freezing temperature of the cement-stabilized crushed stone base, in °C;

[0086] ω is the moisture content of the cement-stabilized gravel base;

[0087] a1, b1, c1 are parameters;

[0088] The attenuation equation of the modulus of cement-stabilized crushed stone structure under traffic load is as follows:

[0089]

[0090]

[0091]

[0092]

[0093] Wherein, N is the fatigue life of cement-stabilized crushed stone base, in times;

[0094] k a is the adjustment coefficient for seasonally frozen areas; it can be obtained from the "Highway Asphalt Pavement Design Specification" JTG D50-2017;

[0095] k T2 is the temperature adjustment coefficient, which can be obtained from Appendix G of the "Highway Asphalt Pavement Design Specification" JTG D50-2017;

[0096] R is the flexural strength of the cement-stabilized crushed stone base material, in MPa;

[0097] σ is the maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer, in MPa;

[0098] k c is the on-site comprehensive correction coefficient;

[0099] h a 、h b They are the thickness of asphalt surface layer and cement stabilized macadam base layer of asphalt pavement respectively;

[0100] β is the target reliability index, which can be obtained from the "Highway Asphalt Pavement Design Specification" JTG D50-2017;

[0101] D is the amount of base layer damage;

[0102] n is the number of traffic load loading times, in times;

[0103] E D is the structural modulus of the cement-stabilized crushed stone base when the damage reaches D, in MPa;

[0104] E0 is the initial structural modulus of the cement-stabilized crushed stone base, in MPa;

[0105] a2 and b2 are parameters;

[0106] Step 3: Use multi-layer elastomer analysis software to establish a road structure calculation model for the asphalt pavement; the traffic load uses the BZZ-100 standard axle load, the thickness of each structural layer in the software uses the thickness of the existing pavement structure layer, and the modulus of each structural layer uses the initial structural modulus. The maximum tensile stress σ at the bottom of the cement-stabilized crushed stone base layer is calculated;

[0107] Step 4: Calculate the fatigue life N of the cement-stabilized crushed stone base according to equations (2) and (3);

[0108] Step 5: The current structural modulus E of the cement stabilized gravel base D1 As the structural modulus E of the cement-stabilized crushed stone base when the damage reaches D D , together with the initial structural modulus E0 of the cement-stabilized crushed stone base, the current damage amount D1 of the base is calculated using formula (5);

[0109] Step 6: Based on Miner's law, design the number of axle load actions n according to the single lane equivalent in one year i , calculate the damage amount D2 of cement-stabilized crushed stone base after one year of traffic load. The specific formula is as follows:

[0110] D2=D1+n i / N formula (6);

[0111] Step 7: Using the initial structural modulus E0 of the cement-stabilized gravel base and the damage amount D2 of the cement-stabilized gravel base after one year of traffic load, the structural modulus E0 of the cement-stabilized gravel base after one year of traffic load is obtained using formula (5). D2 ;

[0112] Step 8: Combine the structural modulus E of the cement-stabilized gravel base after one year of traffic load D2 As well as the number of freeze-thaw cycles, freezing temperature and freeze-thaw humidity of the base layer in a year, the modulus estimation method of the base layer under freeze-thaw cycles is used to calculate the structural modulus E of the cement-stabilized crushed stone base layer after a one-year freeze-thaw cycle. D3 ;

[0113] Step 9: Use cement to stabilize the gravel base and obtain the structural modulus E after one year of freeze-thaw cycle. D3 and the initial structural modulus E0 of the cement-stabilized crushed stone base, and the damage amount D3 of the cement-stabilized crushed stone base after one year of freeze-thaw cycle is calculated by formula (5);

[0114] Step 10: Repeat steps 6 to 9 to calculate the damage accumulation of the cement-stabilized gravel base under traffic load and freeze-thaw cycles until the damage amount D=1;

[0115] The sum of the times the cement-stabilized gravel base layer is subjected to the equivalent design axle load before the damage amount D reaches 1 is the remaining life of the active base layer; the sum of the calculated years is the remaining service life of the active base layer.

[0116] In certain embodiments, the method for estimating the modulus of the base layer under freeze-thaw cycles in step 8 is as follows:

[0117] Step 8.1: Assume that the cement-stabilized crushed stone base material experiences m1 and m2 freeze-thaw cycles in a year under two different freeze-thaw temperature and humidity conditions.

[0118] Each freeze-thaw temperature and humidity condition refers to a combination of freezing temperature and freeze-thaw humidity, and the two freeze-thaw temperature and humidity conditions are a first combination condition including a first freezing temperature t1 and a first freeze-thaw humidity ω1, and a second combination condition including a second freezing temperature t2 and a second freeze-thaw humidity ω2;

[0119] Step 8.2: The structural modulus E of the cement-stabilized crushed stone base after one year of traffic load D2 Multiply by 2 and convert to material modulus E m ; Multiply the initial structural modulus E0 of the cement stabilized gravel base by 2 and convert it into the initial material modulus E C0 ;

[0120] Step 8.3: Calculate the material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition. m1 The specific process is as follows:

[0121] The material modulus E m , initial material modulus E C0 , the first freezing temperature t1 and the first freeze-thaw humidity ω1 are substituted into formula (1) to calculate the corresponding material modulus E under the first combination condition m The first equivalent freeze-thaw number p1;

[0122] Then the initial material modulus E C0 , the first freezing temperature t1, the first freeze-thaw humidity ω1 and p1+m1 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition. m1 ;

[0123] Step 8.4: Calculate the material modulus E of the cement-stabilized crushed stone base after m2 freeze-thaw cycles under the second combination condition. m2 The specific process is as follows:

[0124] The material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition is m1 , initial material modulus E C0, the second freezing temperature t2 and the second freeze-thaw humidity ω2 are substituted into formula (1) to calculate the corresponding E under the second combination condition. m1 The second equivalent freeze-thaw number p2;

[0125] Then the initial material modulus E C0 , the second freezing temperature t2, the second freeze-thaw humidity ω2 and p2+m2 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m2 freeze-thaw cycles under the second combination condition. m2 ;E m2 It is the material modulus of the cement-stabilized crushed stone base after experiencing m1 and m2 freeze-thaw cycles under two freeze-thaw temperature and humidity conditions;

[0126] Step 8.5, E m2 Multiply by 0.5 as the structural modulus of the cement-stabilized gravel base after experiencing m1 and m2 freeze-thaw cycles under two freeze-thaw temperature and humidity conditions, that is, the structural modulus E of the cement-stabilized gravel base after one year of freeze-thaw cycle. D3 .

[0127] like Figure 2 As shown, in some embodiments, if there are more than three freeze-thaw temperature and humidity conditions in step 8.1, step 8.4 is repeated to calculate the base structure modulus of the cement-stabilized gravel base after multiple freeze-thaw cycles under all freeze-thaw temperature and humidity conditions.

[0128] In certain embodiments, a1 = -0.1297; b1 = 0.2511; c1 = 0.1432.

[0129] According to the Test Procedure for Stabilized Materials with Inorganic Binders for Highway Engineering (JTG E51-2009), cylindrical specimens of cement-stabilized crushed stone with different gradations and cement contents were made and used in indoor freeze-thaw cycle tests.

[0130] In the experiment, the different gradations were suspended dense and skeleton dense, two common gradations. The different cement content was 4%, 5%, and 6%. The indoor freeze-thaw cycle test conditions are shown in Table 1.

[0131] Table 1 Indoor freeze-thaw cycle test conditions

[0132] Group Moisture content (%) Freezing temperature (℃) Cement stabilized gravel material mix ratio A 5 -18 x-4, x-5, x-6, g-4, g-5, g-6 B 5 -5 x-5, g-5 C 4 -18 x-5, g-5 D 4 -10 x-5, g-5 E 3 -10 x-5, g-5 F 3 -5 x-5, g-5

[0133] In the table, x represents the suspended dense gradation, g represents the skeleton dense gradation, and the numbers represent the cement content. For example, x-4 represents a suspended dense cement-stabilized crushed stone base material with 4% cement added.

[0134] The specifications of cylindrical specimens are:

[0135] There shall be no less than 9 parallel cylindrical specimens with the same gradation and cement content.

[0136] The freeze-thaw temperature conditions are: freezing temperatures are -5°C, -10°C, and -18°C, and melting temperature is 20°C.

[0137] The freeze-thaw humidity conditions were as follows: the moisture contents of the cylindrical specimens were 3%, 4%, and 5%, respectively.

[0138] A complete freeze-thaw cycle is as follows: freeze the cylindrical specimen at a certain freezing temperature for 16 hours, then melt the cylindrical specimen at a 20°C melting temperature for 8 hours. A complete freeze-thaw cycle takes 24 hours.

[0139] Cement-stabilized crushed stone cylindrical specimens were subjected to indoor freeze-thaw cycle tests under varying freeze-thaw temperature and freeze-thaw humidity conditions. The material modulus of the cylindrical specimens was measured after 0, 5, 10, 15, and 20 freeze-thaw cycles using the uniaxial compression modulus test method, according to the "Highway Asphalt Pavement Design Specification" (JTG D50-2017). The material modulus at 0 freeze-thaw cycle was used as the initial material modulus of the cement-stabilized crushed stone. The test results are shown in Table 2.

[0140] Table 2 Indoor freeze-thaw cycle test results

[0141]

[0142]

[0143] According to the material modulus after freeze-thaw cycles measured under different freeze-thaw temperature conditions and freeze-thaw humidity conditions, the attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles was established. The attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles is:

[0144]

[0145] Among them, E m is the material modulus after m freeze-thaw cycles, in MPa;

[0146] E C0 is the initial material modulus, in MPa;

[0147] t is the freezing temperature of the cement-stabilized crushed stone base, in °C;

[0148] ω is the moisture content of the cement-stabilized gravel base;

[0149] a1, b1, c1 are parameters.

[0150] Finally, we get a1 = -0.1297; b1 = 0.2511; c1 = 0.1432. Comparison of the measured data of the base material modulus with the data calculated by the attenuation equation, as shown in the following example: Figure 3 shown.

[0151] In certain embodiments, a2=11.0446; b2=3.8362.

[0152] The accelerated loading test section data of cement-stabilized crushed stone base asphalt pavement at home and abroad were collected to clarify the thickness of each structural layer in the accelerated loading test section, the initial structural modulus of each structural layer, the traffic load conditions, and the flexural and tensile strength of the cement-stabilized crushed stone base material. The number of traffic load loading times and the base structure modulus data during the accelerated loading test were obtained.

[0153] Eleven accelerated loading test section data were obtained, with section numbers A2, B1, B2, EXP3301, Exp3302, Exp3304, Exp3307, Exp3308, Exp3309, Exp3310, and Exp3311.

[0154] The thicknesses of the A2, B1, and B2 structural layers are shown in Table 3. The thicknesses of the EXP3301, Exp3302, Exp3304, Exp3307, Exp3308, Exp3309, Exp3310, and Exp3311 structural layers are shown in Table 4. The initial structural moduli of each structural layer for the 11 test sections are shown in Tables 5 and 6, the traffic load conditions are shown in Tables 7 and 8, the flexural and tensile strengths of the cement-stabilized crushed stone base material are shown in Tables 9 and 10, and the traffic load loading times and base structural modulus data during the accelerated loading test are shown in Table 11.

[0155] Table 3 Thickness of each structural layer in the test section

[0156] Stratum Surface grassroots Subbase roadbed Material asphalt mixture Cement-stabilized gravel Sandy / silty soil gravel thickness 3cm 18cm 20cm >2m

[0157] Table 4 Thickness of each structural layer in the test section

[0158]

[0159] Table 5 Initial structural modulus of each structural layer

[0160]

[0161] Table 6 Initial structural modulus of each structural layer

[0162]

[0163]

[0164] Table 7 Traffic load conditions of the test section

[0165]

[0166] Table 8 Traffic load conditions of the test section

[0167]

[0168] Table 9 Flexural strength of cement stabilized crushed stone base materials

[0169]

[0170] Table 10 Flexural strength of cement stabilized crushed stone base materials

[0171]

[0172]

[0173] The maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer was determined for each test section. BISAR analysis software was used to establish a road structure calculation model for the asphalt pavement. The traffic load conditions in Tables 7 and 8 were used, the thicknesses of each structural layer were based on the thicknesses in Tables 3 and 4, and the initial structural moduli in Tables 5 and 6 were used for each structural layer. The maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer was calculated, and the results are shown in Tables 12 and 13.

[0174] Table 12 Maximum tensile stress at the bottom of cement-stabilized crushed stone base layer in each test section

[0175]

[0176] Table 13 Maximum tensile stress at the bottom of cement-stabilized crushed stone base layer in each test section

[0177]

[0178] According to the "Highway Asphalt Pavement Design Specification" JTG D50-2017, the fatigue life of the base layer was determined. The calculation results of the fatigue life of the base layer in each test section are shown in Tables 14 and 15. The calculation formula for the fatigue life of the base layer is:

[0179]

[0180]

[0181] Wherein, N is the fatigue life of cement-stabilized crushed stone base, in times;

[0182] k a is the adjustment coefficient for seasonally frozen areas; it can be obtained from the "Highway Asphalt Pavement Design Specification" JTG D50-2017;

[0183] k T2is the temperature adjustment coefficient, which can be obtained from Appendix G of the "Highway Asphalt Pavement Design Specification" JTG D50-2017;

[0184] R is the flexural strength of the cement-stabilized crushed stone base material, in MPa;

[0185] σ is the maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer, in MPa;

[0186] k c is the on-site comprehensive correction coefficient;

[0187] h a 、h b They are the thickness of asphalt surface layer and cement stabilized macadam base layer of asphalt pavement respectively;

[0188] β is the target reliability index, which can be obtained from the "Highway Asphalt Pavement Design Specification" JTG D50-2017.

[0189] Table 14 Calculation results of fatigue life of base layer in each test section

[0190]

[0191] Table 15 Calculation results of fatigue life of base layer in each test section

[0192]

[0193] Combined with the data in Table 11, the attenuation equation of the modulus of the cement-stabilized crushed stone structure under traffic load is established, which is:

[0194]

[0195]

[0196] Where D is the amount of base layer damage;

[0197] n is the number of traffic load loading times, in times;

[0198] E D is the structural modulus of the cement-stabilized crushed stone base when the damage reaches D, in MPa;

[0199] E0 is the initial structural modulus of the cement-stabilized crushed stone base, in MPa;

[0200] a2 and b2 are parameters.

[0201] Finally, we get a2=11.0446; b2=3.8362. Comparison of measured data of base structure modulus and calculated data of attenuation equation Figure 4 shown.

[0202] Example 2

[0203] like Figure 1 As shown in the figure, the remaining life of the existing cement-stabilized gravel base can be estimated by using the attenuation equations for the modulus of cement-stabilized gravel materials under freeze-thaw cycles and the attenuation equations for the structural modulus of cement-stabilized gravel under traffic loads. The specific process for estimating the remaining life of cement-stabilized gravel base is as follows:

[0204] Project example: Take a highway that was completed and opened to traffic in a certain year as an example. The highway is a first-class highway located in a medium-frozen area. The designed service life is 15 years. It has been in operation for 6 consecutive years. Estimate the remaining life and remaining service life of the existing cement-stabilized gravel base.

[0205] The thickness of each structural layer and the initial structural modulus of each structural layer are obtained, where the initial structural modulus of the cement-stabilized crushed stone base is recorded as E0.

[0206] There are three main ways to obtain the initial structural modulus of each structural layer:

[0207] (1) Obtain the initial structural modulus of each structural layer through road design data or completion acceptance data.

[0208] (2) The pavement deflection basin parameters are detected by a falling weight deflectometer (FWD) on the shoulder or emergency lane, and the initial structural modulus of each structural layer is calculated by the modulus back calculation method.

[0209] (3) Drill a core sample of the base layer on the shoulder or emergency lane, and measure the material modulus of the cylindrical specimen using the "Uniaxial Compression Modulus Test Method" according to the "Highway Asphalt Pavement Design Code" JTGD50-2017. Multiply the material modulus by 0.5 to convert it into a structural modulus, which is used as the initial structural modulus of the base layer.

[0210] In this project, a falling weight deflectometer (FWD) was used to measure the pavement deflection basin parameters in the emergency lane. The initial structural modulus of each structural layer was calculated using the modulus inverse method. The thickness and initial structural modulus of each structural layer in this project are shown in Table 16.

[0211] Table 16 Thickness of each structural layer and initial structural modulus

[0212] Structural layer thickness Initial structural modulus (MPa) Asphalt surface 7 10200 Cement stabilized gravel base 40 13123 roadbed — 104

[0213] Obtain the flexural tensile strength R of the cement-stabilized crushed stone base material.

[0214] There are two main ways to obtain the flexural strength of cement-stabilized crushed stone base materials:

[0215] (1) Obtain the flexural and tensile strength of the base material through road design data or completion acceptance data.

[0216] (2) Drill a core sample of the base layer on the shoulder or emergency lane and measure the unconfined compressive strength of the cylindrical specimen according to the "Test Procedure for Stabilized Materials with Inorganic Binders for Highway Engineering" JTG E51-2009. Multiply the compressive strength by 0.21 to obtain the flexural tensile strength of the base layer.

[0217] In this project, core samples of the base layer were drilled from the emergency lane, and the average unconfined compressive strength of the specimens was measured to be 7.24 MPa. This compressive strength was multiplied by 0.21 to obtain 1.52 MPa, which was used as the flexural tensile strength of the cement-stabilized crushed stone base material.

[0218] Get the current structural modulus E of the cement-stabilized gravel base at the wheel track of the roadway D1 .

[0219] At the wheel track of the driving lane, the pavement deflection basin parameters were detected by a falling weight deflectometer (FWD), and the current structural modulus of the cement-stabilized gravel base was calculated using the modulus back calculation method.

[0220] The current structural modulus of the existing cement-stabilized gravel base calculated in this project is 7547 MPa.

[0221] Determine the number of times n the equivalent design axle load of a single lane is applied each year i .

[0222] The number of equivalent design axle load actions on a single lane in the initial year and the average annual growth rate of traffic volume can be obtained from the road design data. The number of equivalent design axle load actions on a single lane each year after the road is built can be calculated using the following formula: i .

[0223] n i =n1×(1+r) i-1 ;

[0224] Where n i is the number of times the single lane equivalent design axle load acts in the i-th year (times); n1 is the number of times the single lane equivalent design axle load acts in the initial year (times); r represents the average annual growth rate of traffic volume.

[0225] The number of equivalent design axle load actions on a single lane in the initial year of this project is 4.73×10 7 The average annual growth rate of traffic volume is 3%. The number of times the equivalent design axle load of a single lane acts each year is calculated. The number of times the equivalent design axle load of a single lane acts from the first to the fifteenth year is: 4.73×10 7 times, 4.88×10 7 times, 5.02×10 7 times, 5.17×10 7 times, 5.33×10 7times, 5.49×10 7 times, 5.65×10 7 times, 5.82×10 7 times, 6.00×10 7 times, 6.18×10 7 times, 6.36×10 7 times, 6.55×10 7 times, 6.75×10 7 times, 6.95×10 7 times, 7.16×10 7 Second-rate.

[0226] Determine the number of freeze-thaw cycles, freezing temperature, and freeze-thaw humidity of the base layer in a year.

[0227] The basis for determining whether a freeze-thaw cycle has occurred in the base layer is as follows: the temperature in the middle of the base layer drops from above 0℃ to below 0℃ and remains below 0℃ for more than 2 hours, which is a freezing; the temperature in the middle of the base layer rises from below 0℃ to above 0℃ and remains above 0℃ for more than 2 hours, which is a melting. Together, they constitute a complete freeze-thaw cycle.

[0228] There are two main ways to obtain the number of freeze-thaw cycles and freeze-thaw temperature conditions of the base layer:

[0229] (1) The temperature change in the middle of the base layer is obtained by using a thermometer pre-buried in the base layer to determine the number of freeze-thaw cycles of the base layer, and the lowest temperature in a freezing cycle is used as the freezing temperature of that freezing-thaw cycle.

[0230] (2) Using local temperature data and the pavement temperature estimation method, the temperature change in the middle of the base layer is estimated to determine the number of freeze-thaw cycles of the base layer, and the lowest temperature in a freezing cycle is used as the freezing temperature of that freezing-thaw cycle.

[0231] The road surface temperature estimation method specifically includes: a daily temperature variation model, a road surface temperature estimation model, and a temperature estimation model at different depths of the road. The road surface temperature estimation method is not protected by this patent.

[0232] The daily temperature variation model uses the daily maximum temperature and daily minimum temperature to better estimate the daily temperature variation process over time. The model expression is:

[0233] T a =T b +T c [0.96sinw(v-v0)+0.14sin2w(v-v0)] Formula (6);

[0234]

[0235]

[0236] Where, T a Indicates the temperature in °C; T b is the daily average temperature, in °C; T c is the daily temperature amplitude, in °C; is the maximum daily temperature, in °C; is the daily minimum temperature, in °C;

[0237] v0 is the difference between the time of maximum solar radiation (12 noon solar time) and the time of maximum temperature plus 1, generally v0 = 3 (hours);

[0238] v is time, and it is specified that at 6 o'clock in the morning (solar time), v = 0 (hour);

[0239] w is the angular frequency, w=2π / 24 (1 / hour).

[0240] The road surface temperature prediction model uses the average temperature of the previous five hours and the average monthly temperature over the years to better predict the road surface temperature at different times. The model expression is:

[0241] T p =-0.425+1.239T aS +0.08T m Formula (9)

[0242] Where, T p Indicates the surface temperature of asphalt pavement (℃); T a5 Indicates the average temperature in the previous 5 hours (℃); T m It represents the regional correction coefficient, i.e. the monthly average temperature over the years (℃).

[0243] The temperature estimation model at different depths of the road can better estimate the temperature at any depth of the pavement structure using the road surface temperature. The model expression is:

[0244]

[0245]

[0246]

[0247]

[0248] Where, T h represents the daily maximum temperature at a certain depth of the road surface (°C); T1 represents the daily minimum temperature at a certain depth of the road surface (°C); Z represents the road surface depth, which is the road surface depth at the middle of the base layer (mm); T s.y Indicates the annual average temperature of the road surface (℃); Ts Indicates the average temperature of the road surface for one or several days (℃). When Z < 100mm, the average temperature is calculated. When Z ≥ 100mm, the statistical period is increased by 1 day. s.h1 It indicates the daily temperature difference of the road surface, which is the difference between the daily maximum and minimum temperatures of the road surface (°C); α indicates the thermal conductivity of the material, which is 0.0032 (m 2 / h).

[0249] Furthermore, based on the overall trend and most cases, regional temperature fluctuations follow a cyclical pattern. Therefore, we can use local historical temperature average statistics (average daily maximum and minimum temperatures, and monthly average temperatures) to estimate temperature variations in the middle of the basement over the course of a year, thereby determining the basement freezing temperature and freeze-thaw frequency within a year.

[0250] This project example uses the local historical temperature average statistical data (average daily maximum temperature, average daily minimum temperature, and monthly average temperature over the years) and adopts the pavement temperature estimation method to calculate that the number of freeze-thaw cycles of the base layer in a year is 20 times, and the freezing temperatures are -0.8℃, -2.2℃, -0.5℃, -0.7℃, -0.7℃, -0.7℃, -0.6℃, -1.3℃, -17.9℃, -0.3℃, -0.1℃, -1.4℃, -2.5℃, -1.7℃, -1.8℃, -2.6℃, -2.4℃, -2.3℃, -1.6℃, and -0.2℃.

[0251] There are two main ways to obtain the freeze-thaw humidity of the base layer:

[0252] (1) Obtain the base layer humidity through a hygrometer pre-buried in the base layer.

[0253] (2) Drill core samples of the base layer and measure the average moisture content of the core samples.

[0254] Furthermore, the cement-stabilized macadam base layer is located beneath the asphalt surface layer, and its moisture content is less affected by atmospheric humidity and precipitation. Therefore, the base layer moisture content fluctuates less, and the moisture content measured by the base layer core sample can be used as the base layer freeze-thaw moisture content.

[0255] In this project, core samples of the base layer were drilled and the average moisture content of the core samples was measured to be 1.3%.

[0256] Calculate the maximum tensile stress σ at the bottom of the cement-stabilized crushed stone base layer. Use multilayer elastomer analysis software to establish a road structure calculation model. Use the BZZ-100 standard axle load for traffic load, the thickness of each structural layer based on the thickness of the existing pavement structure layer, and the initial structural modulus for each structural layer to calculate the maximum tensile stress at the bottom of the base layer.

[0257] In this project example, the maximum tensile stress at the bottom of the base layer was calculated using BISAR calculation software to be 0.3023 MPa.

[0258] Calculate the fatigue life N of the cement-stabilized crushed stone base. According to the "Highway Asphalt Pavement Design Code" JTG D50-2017, the fatigue life of the base is determined. The base fatigue life calculation formula is Equation (2) and Equation (3).

[0259] This project example refers to the "Highway Asphalt Pavement Design Code" JTG D50-2017, and the value of k is obtained according to the local climate conditions, pavement structure combination and highway grade. a Take it as 0.79, k T2 Take it as 0.76, k c is taken as -1.077, β is taken as 1.28, and the fatigue life of the base layer N is 9.11×10 8 Second-rate.

[0260] Calculate the damage amount D1 corresponding to the current structural modulus of the base layer. Use the current structural modulus E of the base layer D1 and the initial structural modulus E0 of the base layer, the current damage amount D1 of the base layer is calculated using formula (5).

[0261] Calculate the damage D2 of the base after one year of traffic load. Based on Miner's law, the number of axle loads n is designed according to the equivalent of one lane in one year. i , use formula (6) to calculate the damage amount D2 of the base after being subjected to one year of traffic load.

[0262] D2=D1+n i / N Formula (6)

[0263] Calculate the structural modulus E of the base after one year of traffic load D2 Using the initial structural modulus E0 and damage amount D2 of the base layer, and using formula (5), the structural modulus E of the base layer after one year of traffic load is obtained. D2 .

[0264] Calculate the structural modulus E of the base after one year of freeze-thaw cycle D3 Combined structural modulus E D2 As well as the number of freeze-thaw cycles, freezing temperature and freeze-thaw humidity of the base layer in a year, the base layer modulus estimation method under freeze-thaw cycles is used to calculate the structural modulus E of the base layer after being subjected to one year of freeze-thaw cycles. D3 .

[0265] Calculate the damage D3 of the base after one year of freeze-thaw cycle. Using the structural modulus E D3 And the initial structural modulus E0 of the base layer, the damage amount D3 of the base layer after one year of freeze-thaw cycle is calculated through formula (5).

[0266] Calculate the remaining life and remaining service life of the base layer. Repeat the above four steps, calculating the cumulative damage to the base layer under traffic loads and freeze-thaw cycles, in years, until the damage amount D = 1. Sum the number of equivalent design axle loads applied to the base layer before the damage amount D reaches 1 to obtain the remaining life of the active base layer. Sum the calculated years to obtain the remaining service life of the active base layer.

[0267] In this project, the remaining life of the existing cement-stabilized gravel base was calculated to be 4.70×10 8 The remaining useful life is 7 years.

[0268] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for estimating the remaining life of cement-stabilized macadam base of asphalt pavement based on modulus; characterized by: The process includes the following steps: Step 1: Obtain the thickness of each structural layer and the initial structural modulus of each structural layer in the asphalt pavement corresponding to the cement-stabilized crushed stone base for which remaining life estimation is required; wherein the initial structural modulus of the cement-stabilized crushed stone base is denoted as E0; Obtaining the flexural tensile strength R of the cement-stabilized crushed stone base material; Obtain the current structural modulus E of the cement-stabilized macadam base at the wheel track of the asphalt pavement D1 ; Determine the number of times n the equivalent design axle load of a single lane acts on the asphalt pavement each year i ; Determine the freeze-thaw frequency, freezing temperature and freeze-thaw humidity of the cement-stabilized crushed stone base layer in one year; Step 2: Establish the attenuation equation of the modulus of cement-stabilized crushed stone material under freeze-thaw cycles and the attenuation equation of the modulus of cement-stabilized crushed stone structure under traffic loads; The attenuation equation of the modulus of cement-stabilized crushed stone material under the freeze-thaw cycle is as follows: Among them, E m is the material modulus after m freeze-thaw cycles, in MPa; E C0 is the initial material modulus, in MPa; t is the freezing temperature of the cement-stabilized crushed stone base, in °C; ω is the moisture content of the cement-stabilized gravel base; a1, b1, c1 are parameters; The attenuation equation of the modulus of the cement-stabilized crushed stone structure under traffic load is as follows: Wherein, N is the fatigue life of the cement stabilized crushed stone base, in times; k a is the adjustment coefficient for seasonally frozen areas; k T2 is the temperature adjustment coefficient; R is the flexural tensile strength of the cement-stabilized crushed stone base material, in MPa; σ is the maximum tensile stress at the bottom of the cement-stabilized crushed stone base layer, in MPa; k c is the on-site comprehensive correction coefficient; h a 、h b are the thickness of the asphalt surface layer of the asphalt pavement and the thickness of the cement-stabilized macadam base layer respectively; β is the target reliability indicator; D is the amount of base layer damage; n is the number of traffic load loading times, in times; E D is the structural modulus of the cement-stabilized crushed stone base when the damage reaches D, in MPa; E0 is the initial structural modulus of the cement-stabilized crushed stone base, in MPa; a2 and b2 are parameters; Step 3: Using multi-layer elastomer analysis software to establish a road structure calculation model for the asphalt pavement; wherein the traffic load adopts the BZZ-100 standard axle load, the thickness of each structural layer in the software adopts the thickness of the existing pavement structure layer, and the modulus of each structural layer adopts the initial structural modulus, and the maximum tensile stress σ at the bottom of the cement-stabilized crushed stone base layer is calculated; Step 4: Calculate the fatigue life N of the cement-stabilized crushed stone base according to equations (2) and (3); Step 5: The current structural modulus E of the cement stabilized gravel base D1 As the structural modulus E of the cement stabilized crushed stone base when the damage amount reaches D D , together with the initial structural modulus E0 of the cement-stabilized crushed stone base, the current damage amount D1 of the base is calculated using formula (5); Step 6: Based on Miner's law, design the number of axle load actions n according to the single lane equivalent in one year i , calculate the damage amount D2 of the cement-stabilized gravel base after one year of traffic load, the specific formula is as follows: D2=D1+n i / N formula (6); Step 7: Using the initial structural modulus E0 of the cement-stabilized gravel base and the damage amount D2 of the cement-stabilized gravel base after one year of traffic load, the structural modulus E0 of the cement-stabilized gravel base after one year of traffic load is obtained using formula (5). D2 ; Step 8: Combine the structural modulus E of the cement stabilized gravel base after one year of traffic load D2 As well as the number of freeze-thaw cycles, freezing temperature and freeze-thaw humidity of the base layer in one year, the base modulus estimation method under freeze-thaw cycles is used to calculate the structural modulus E of the cement-stabilized crushed stone base layer after one year of freeze-thaw cycles. D3 ; Step 9: Using the structural modulus E of the cement-stabilized gravel base after one year of freeze-thaw cycle D3 and the initial structural modulus E0 of the cement-stabilized crushed stone base, and the damage amount D3 of the cement-stabilized crushed stone base after one year of freeze-thaw cycle is calculated by formula (5); Step 10: Repeat steps 6 to 9 to calculate the damage accumulation of the cement-stabilized gravel base under traffic load and freeze-thaw cycles until the damage amount D=1; The sum of the times the cement-stabilized gravel base layer is subjected to the equivalent design axle load before the damage amount D reaches 1 is the remaining life of the active base layer; the sum of the calculated years is the remaining service life of the active base layer.

2. The method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus according to claim 1 is characterized in that: The method for estimating the modulus of the base layer under freeze-thaw cycles described in step 8 is as follows: Step 8.1: Assume that the cement-stabilized crushed stone base material experiences m1 and m2 freeze-thaw cycles under two freeze-thaw temperature and humidity conditions in one year; Each of the freeze-thaw temperature and humidity conditions refers to a combination of freezing temperature and freeze-thaw humidity, and the two freeze-thaw temperature and humidity conditions are a first combination condition including a first freezing temperature t1 and a first freeze-thaw humidity ω1, and a second combination condition including a second freezing temperature t2 and a second freeze-thaw humidity ω2; Step 8.2: The structural modulus E of the cement-stabilized crushed stone base after one year of traffic load D2 Multiply by 2 and convert to material modulus E m The initial structural modulus E0 of the cement stabilized macadam base is multiplied by 2 and converted into the initial material modulus E C0 ; Step 8.3: Calculate the material modulus E of the cement-stabilized gravel base after m1 freeze-thaw cycles under the first combination condition. m1 The specific process is as follows: The material modulus E m , the initial material modulus E C0 , the first freezing temperature t1 and the first freeze-thaw humidity ω1 are substituted into formula (1) to calculate the material modulus E corresponding to the first combination condition. m The first equivalent freeze-thaw number p1; Then the initial material modulus E C0 , the first freezing temperature t1, the first freeze-thaw humidity ω1 and p1+m1 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition. m1 ; Step 8.4: Calculate the material modulus E of the cement-stabilized gravel base after m2 freeze-thaw cycles under the second combination condition. m2 The specific process is as follows: The material modulus E of the cement-stabilized crushed stone base after m1 freeze-thaw cycles under the first combination condition is m1 , the initial material modulus E C0 , the second freezing temperature t2 and the second freeze-thaw humidity ω2 are substituted into formula (1) to calculate the corresponding E under the second combination condition m1 The second equivalent freeze-thaw number p2; Then the initial material modulus E C0 , the second freezing temperature t2, the second freeze-thaw humidity ω2 and p2+m2 as m are substituted into formula (1) to calculate the material modulus E of the cement-stabilized crushed stone base after m2 freeze-thaw cycles under the second combination condition. m2 ;E m2 That is, the material modulus of the cement-stabilized crushed stone base after experiencing m1 and m2 freeze-thaw cycles under the two freeze-thaw temperature and humidity conditions; Step 8.5, E m2 Multiply by 0.5 as the structural modulus of the cement-stabilized gravel base after experiencing m1 and m2 freeze-thaw cycles under the two freeze-thaw temperature and humidity conditions, that is, the structural modulus E of the cement-stabilized gravel base after one year of freeze-thaw cycle. D3 .

3. The method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus according to claim 2 is characterized in that: If there are more than three freeze-thaw temperature and humidity conditions in step 8.1, repeat step 8.4 to calculate the base structure modulus of the cement-stabilized crushed stone base after multiple freeze-thaw cycles under all the freeze-thaw temperature and humidity conditions.

4. The method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus according to claim 1 is characterized in that: a1=-0.1297; b1=0.2511; c1=0.1432.

5. The method for estimating the remaining life of an asphalt pavement cement-stabilized macadam base based on modulus according to claim 1 is characterized in that: <h2 style=";text-align:left;direction:ltr">a2=11.0446;b2=3.8362。

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