A composite road surface rut prediction method

Abstract

The application discloses a composite pavement rut estimation method, which comprises the following steps: S1, determining the design parameter value of the asphalt surface layer of the composite pavement; S2, determining the interlayer friction coefficient of the composite pavement; S3, calculating the vertical pressure stress correction coefficient of the interlayer contact; S4, determining the road section speed; and S5, calculating the rut depth of the composite pavement according to the data of steps S1-S4. The rut is estimated in combination with the interlayer contact state and driving speed of the composite pavement, so that the rut estimation result is more consistent with the actual situation.

Description

Technical Field

[0001] This invention belongs to the field of composite pavement, specifically relating to a method for predicting rutting in composite pavement. Background Technology

[0002] Composite pavement is a road surface composed of two structural layers of different types and mechanical properties. It has the advantages of concrete pavement, such as high durability, strong load-bearing capacity and long service life, while also having the characteristics of asphalt concrete pavement, such as smooth surface, comfortable driving, convenient maintenance and low noise. It is a road structure form with good development prospects.

[0003] In engineering practice, it has been found that the asphalt surface layer of composite pavements is prone to significant rutting under repeated traffic loads and temperature stresses, affecting driving safety and pavement performance. Compared to semi-rigid base asphalt pavements, the contact between the asphalt concrete layer and the cement concrete layer in composite pavements is a weak point, easily leading to sliding shear failure under load. Engineering practice shows a significant correlation between this failure and rutting. Furthermore, road maintenance has revealed a certain relationship between rutting on composite pavements and vehicle speed.

[0004] Current pavement design is mainly completed according to standards such as the "Standard Specification for Design of Highway Asphalt Pavement" (JTGD50-2017) and the "Specification for Asphalt Pavement of Urban Roads" (CJJ-169). The rutting calculation model does not consider the influence of interlayer contact state and driving speed, which leads to inaccurate rutting prediction and a large difference from the actual rutting. Summary of the Invention

[0005] The purpose of this invention is to provide a method for predicting rutting in composite pavements. This method combines the interlayer contact state of the composite pavement with the vehicle speed to predict rutting, making the rutting prediction results more consistent with the actual situation.

[0006] The technical solution adopted in this invention is:

[0007] A composite method for predicting road rutting includes the following steps:

[0008] S1. Determine the relevant design parameter values ​​for composite pavement asphalt surface layer;

[0009] S2, determine the interlayer friction coefficient of composite pavement;

[0010] S3, the correction factor for vertical compressive stress in interlayer contact;

[0011] S4, determine the speed limit for the road section;

[0012] S5. Calculate the rut depth of the composite road surface based on the data from steps S1-S4.

[0013] According to the above scheme, in step S1, the relevant design parameter values ​​of the composite pavement asphalt surface layer include asphalt layer thickness, asphalt layer modulus, equivalent temperature of permanent deformation of asphalt mixture layer, cumulative number of times of design lane equivalent action, thickness of rutting test specimen, and permanent deformation of the i-th layer of asphalt mixture at test temperature of 60℃, pressure of 0.7MPa, and loading times of 2520 times, comprehensive correction coefficient, and vertical compressive stress on the top surface of the i-th layer of asphalt mixture.

[0014] According to the above scheme, in step S2, the interlayer friction coefficient of the composite pavement... The calculation formula is:

[0015]

[0016] In the formula: The coefficient of friction between composite pavement layers ranges from 0.1 to 1.0. For the interlayer shear strength of composite pavement; This refers to the shear strength of the asphalt layer in composite pavement.

[0017] According to the above scheme, in step S3, the vertical compressive stress correction factor for interlayer contact... The calculation formula is:

[0018]

[0019] In the formula: This is the correction factor for the vertical compressive stress in interlayer contact. The coefficient of friction between composite pavement layers ranges from 0.1 to 1.0.

[0020] According to the above scheme, the interlayer friction coefficient of the composite pavement is taken as a large value when the interlayer bonding effect is good, and a small value is taken as a negative value.

[0021] According to the above scheme, in step S5, the rut depth of the composite pavement The calculation formula is:

[0022]

[0023] In the formula: The permanent deformation of the i-th asphalt mixture layer (mm) is the rutting depth of the composite pavement. —Equivalent temperature of permanent deformation of asphalt mixture (°C); —The cumulative number of times the equivalent lane design is applied; —Thickness of the i-th layer (mm); —Thickness (mm) of the rutting test specimen; —Permanent deformation (mm) of the i-th layer of asphalt mixture under rutting test at a test temperature of 60℃, a pressure of 0.7MPa, and 2520 loading cycles. —Comprehensive correction factor; pi—Vertical compressive stress (MPa) on the top surface of the i-th layer of asphalt mixture; V is vehicle speed (100km / h).

[0024] According to the above plan, in step S4, the speed of vehicles on the road segment is determined according to different road configurations, and may be determined based on traffic survey data if necessary.

[0025] The different road configurations refer to general road sections, at-grade intersections with turns, and crossroads.

[0026] According to the above scheme, the relevant design parameters of the composite pavement asphalt surface layer should be reasonably selected based on the specifications and actual engineering conditions.

[0027] According to the above scheme, in step S5, it is determined whether the rutting depth of the composite pavement meets the specification requirements. If it does not meet the requirements, the pavement structure design is modified until the rutting depth of the composite pavement meets the specification requirements.

[0028] The beneficial effects of this invention are as follows:

[0029] It quantifies the impact of interlayer contact state and vehicle speed on rutting, and is applicable to the accurate prediction of rutting in asphalt pavement of composite pavement. It controls rutting within the specified range during the design stage, avoids or reduces excessive rutting and other defects caused by it during the service of composite pavement asphalt pavement, effectively reduces the operation and maintenance cost of composite pavement, and ensures the service performance of composite pavement from the perspective of rutting control.

[0030] This invention is simple and easy to operate, and can be widely applied in the prediction of rutting in composite road surfaces. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0032] Figure 1 This is a flowchart illustrating the composite road rutting prediction method. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] See Figure 1 A composite method for predicting road ruts includes the following steps:

[0035] S1. Determine the relevant design parameters for the composite pavement asphalt surface layer. These parameters include asphalt layer thickness, asphalt layer modulus, equivalent temperature of permanent deformation of the asphalt mixture layer, cumulative number of load cycles for the design lane, thickness of the rutting test specimen, and the permanent deformation of the i-th asphalt mixture layer under test conditions of 60℃, 0.7MPa, and 2520 load cycles, as well as the comprehensive correction factor and vertical compressive stress on the top surface of the i-th asphalt mixture layer. The above-mentioned design parameters for the composite pavement asphalt surface layer are reasonably selected based on specifications and actual engineering conditions.

[0036] S2, Determine the interlayer friction coefficient of the composite pavement.

[0037] interlayer friction coefficient of composite pavement The calculation formula is:

[0038]

[0039] In the formula: The coefficient of friction between composite pavement layers ranges from 0.1 to 1.0. For the interlayer shear strength of composite pavement; This refers to the shear strength of the asphalt layer in composite pavement.

[0040] S3, Correction factor for vertical compressive stress in interlayer contact calculation

[0041] Vertical compressive stress correction factor for interlayer contact The calculation formula is:

[0042]

[0043] In the formula: This is the correction factor for the vertical compressive stress in interlayer contact. The coefficient of friction between composite pavement layers ranges from 0.1 to 1.0. A larger coefficient of friction is used when the interlayer bonding effect is good, and a smaller coefficient is used when the interlayer bonding effect is poor.

[0044] S4 determines the speed limit for a road segment. The speed limit for this segment is determined separately for different road types, such as general road segments, at-grade intersections, and crossroads. If necessary, it may be determined based on traffic survey data.

[0045] S5, Calculate the rut depth of the composite pavement based on the data from steps S1-S4.

[0046] Composite road rut depth The calculation formula is:

[0047]

[0048] In the formula: The permanent deformation of the i-th asphalt mixture layer (mm) is the rutting depth of the composite pavement. —Equivalent temperature of permanent deformation of asphalt mixture (°C); —The cumulative number of times the equivalent lane design is applied; —Thickness of the i-th layer (mm); —Thickness (mm) of the rutting test specimen; —Permanent deformation (mm) of the i-th layer of asphalt mixture under rutting test at a test temperature of 60℃, a pressure of 0.7MPa, and 2520 loading cycles. —Comprehensive correction factor; pi—Vertical compressive stress on the top surface of the i-th layer of asphalt mixture (MPa); V is vehicle speed (100km / h);

[0049] Determine whether the rutting depth of the composite pavement meets the specifications. If not, modify the pavement structure design until the rutting depth of the composite pavement meets the specifications.

[0050] Specific examples:

[0051] A certain Class I highway adopts an AC+CRC composite pavement structure. The AC layer has a design life of 15 years, a design speed of 80 km / h, and a cumulative axle load application count of 2.1E+07 within the design reference period, classifying it as a heavy traffic load. The initial proposed CRC+AC structure features an AC layer with a total thickness of 120 mm (SMA-13 ​​40 mm + AC-25 80 mm), and a CRC layer thickness of 240 mm. The CRC layer surface is milled, and SBS modified asphalt is sprayed between the layers. The highest summer temperature at the location of this highway is 30℃.

[0052] The rutting amount was calculated according to current specifications without considering interlayer contact conditions and vehicle speed. Using BISAR 3.0 software, the rutting amount was calculated without considering the influence of interlayer contact conditions and vehicle speed. Typical representative values ​​were taken from the specifications, and the calculated rutting amount was 6.26 mm.

[0053] Calculate the interlayer friction coefficient of the composite pavement. Prepare AC-25 asphalt mixture oblique shear test specimens and determine the shear strength of the AC-25 asphalt mixture. =0.8 MPa. AC-25+CRC oblique shear test specimens were prepared, following the procedures outlined in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The interlayer shear strength of the AC-25+CRC specimens was determined. The interlayer treatment was consistent with the design data. The determined interlayer shear strength of AC-25+CRC was... =0.4MPa. Therefore, the interlayer friction coefficient of the composite pavement is... =0.5.

[0054] Calculate the vertical compressive stress correction factor considering interlayer contact. Then, calculate the interlayer friction coefficient of the composite pavement. Substitute into the formula:

[0055]

[0056] The vertical compressive stress correction factor considering interlayer contact is calculated. =1.0679.

[0057] Determine the representative vehicle speed for the road segment. Based on the design data, the road segment is selected as a general road segment, and the vehicle speed is set to V=0.8 (100km / h).

[0058] Calculate the rutting depth of a composite pavement that simultaneously considers interlayer contact conditions and vehicle speed. A vertical compressive stress correction factor considering interlayer contact will be applied. Substitute the vehicle speed V into the equation:

[0059]

[0060] The calculated rut depth of the composite pavement, taking into account both interlayer contact conditions and vehicle speed, is 8.336 mm, which meets the specification requirement of no more than 15 mm.

[0061] Based on the present invention, the design for rutting control of composite pavement is supplemented on the basis of traditional design specifications. It helps to judge whether the composite pavement structure design and interlayer treatment are reasonable, thereby avoiding serious rutting problems in the asphalt surface layer of composite pavement and improving the design level of composite pavement.

[0062] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A composite road rut prediction method, characterized in that, Includes the following steps: S1. Determine the relevant design parameter values ​​for composite pavement asphalt surface layer; S2, determine the interlayer friction coefficient of composite pavement; interlayer friction coefficient of composite pavement The calculation formula is: In the formula: The coefficient of friction between composite pavement layers ranges from 0.1 to 1.

0. For the interlayer shear strength of composite pavement; Shear strength of composite pavement asphalt layer; S3, the correction factor for vertical compressive stress in interlayer contact; Vertical compressive stress correction factor for interlayer contact The calculation formula is: In the formula: This is the correction factor for the vertical compressive stress in interlayer contact. The coefficient of friction between composite pavement layers ranges from 0.1 to 1.

0. A larger value is taken when the interlayer bonding effect is good, and a smaller value is taken when the interlayer bonding effect is poor. S4, determine the speed limit for the road section; S5, Calculate the rut depth of the composite road surface based on the data from steps S1-S4; Composite road rut depth The calculation formula is: In the formula: The permanent deformation of the i-th asphalt mixture layer (mm) is the rutting depth of the composite pavement. —Equivalent temperature of permanent deformation of asphalt mixture (°C); —The cumulative number of times the equivalent lane design is applied; —Thickness of the i-th layer (mm); —Thickness (mm) of the rutting test specimen; —Permanent deformation (mm) of the i-th layer of asphalt mixture under rutting test at a test temperature of 60℃, a pressure of 0.7MPa, and 2520 loading cycles. —Comprehensive correction factor; pi—Vertical compressive stress (MPa) on the top surface of the i-th layer of asphalt mixture; V is vehicle speed (100km / h).

2. The composite road rutting prediction method according to claim 1, characterized in that: In step S1, the relevant design parameters of the composite pavement asphalt surface layer include asphalt layer thickness, asphalt layer modulus, equivalent temperature of permanent deformation of asphalt mixture layer, cumulative number of loads of design lane equivalent, thickness of rutting test specimen, and permanent deformation of the i-th asphalt mixture layer under test temperature of 60℃, pressure of 0.7MPa, and loading times of 2520 times, comprehensive correction coefficient, and vertical compressive stress on the top surface of the i-th layer of asphalt mixture.

3. The composite road rutting prediction method according to claim 1, characterized in that: The relevant design parameters for composite pavement asphalt surface layer should be reasonably selected based on specifications and actual engineering conditions.

4. The composite road rutting prediction method according to claim 1, characterized in that: In step S5, it is determined whether the rutting depth of the composite pavement meets the specification requirements. If it does not meet the requirements, the pavement structure design is modified until the rutting depth of the composite pavement meets the specification requirements.

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