Pavement structure analysis method, electronic equipment and medium

Abstract

The invention provides a pavement structure analysis method, electronic equipment and a medium, and the pavement structure analysis method comprises the following steps: adjusting the type of each structural layer of a pavement and / or the thickness of each structural layer of the pavement, so that the pavement structure meets the requirements of a pavement structure design limit state equation; a method for calculating the accumulated axle load action times based on designed axle loads such as double axles and single axles is established, and a basis is provided for road pavement structure design under different load conditions. The load fatigue stress is calculated according to single-axis, double-axis and other designed load axes under different load conditions, the load fatigue stress calculation result is more accurate, the method can be suitable for pavement structure design under different load conditions, and pavement load characteristics and engineering requirements are better reflected and met.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydropower and water conservancy engineering, and in particular relates to a pavement structure analysis method, electronic equipment and a medium. Background Art

[0002] The main function of hydropower and water conservancy project roads is to meet the transportation needs during the construction period of the power station. Some roads also undertake transportation tasks during the operation period. According to the survey, the types of vehicles passing through the hydropower and water conservancy project roads are mainly double rear axle vehicles (such as Figure 2 ) dump truck, rear three-axle (such as Figure 3 ) and rear five-axle (such as Figure 4 ) Trucks and trailers, while vehicles traveling on my country's highways can be divided into 11 categories. Compared with general highways, hydropower and water conservancy roads have distinct characteristics, including a simple axle load spectrum, concentrated peak traffic volume, widespread and severe overloading, and a large number of special vehicles.

[0003] Currently, cement concrete pavement is the predominant pavement structure for hydropower and water conservancy project roads. The pavement structure design in the "Specifications for the Design of Internal Traffic Roads for Hydropower Projects" (NB / T 10333-2019) and the "Specifications for the Design of Special Highways for External Traffic for Hydropower Projects" (NB / T 35012-2013) both refer to the relevant provisions of the "Specifications for the Design of Cement Concrete Pavements for Highways" (JTG D40). However, the axle loads of vehicles traveling on hydropower and water conservancy project roads are large, and using a 100kN single-axle, double-wheel design axle load would result in an over-conversion of the axle load action times and poor economic efficiency of the pavement structure design. Although the specification proposes that the mainstream axle load (single axle) can be used as the design axle load for extra-heavy and extremely heavy traffic, the transport vehicles of hydropower and water conservancy projects are mainly double-axle and triple-axle with generally large axle loads. When the mainstream axle load (single axle) is used as the design axle load, the stress influence (reduction) degree of the adjacent axle is ignored, thereby affecting the economic efficiency of the pavement structure design. In addition, when the mainstream axle load is used as the design axle load, there is a lack of basis for the selection of important design parameters or load stress calculations in the pavement structure design, such as the traffic load grade classification, the comprehensive rebound modulus value of the roadbed top surface, and the standard value of the flexural tensile strength of cement concrete, which affects the reliability of the pavement structure design.

[0004] The "Design Code for Factory and Mine Roads" (GBJ 22-87) has played an important role in guiding the construction of roads for hydropower and water conservancy projects in my country. However, its pavement structural design fails to consider the effects of temperature stress, varying load conditions, and axle configurations. Its concrete fatigue equations and axle load conversion formulas are crude, and its graphical method for determining pavement thickness results in significant errors, making it inadequate for project design. The "Technical Specification for On-site Construction Roads for Hydropower and Water Conservancy Projects DL / T5243-2010" largely adopts the "Design Code for Factory and Mine Roads" (GBJ 22-87) regarding the design calculation theory and structural design methods for cement concrete pavements. These regulations urgently need to be improved and refined. Summary of the Invention

[0005] The purpose of the present invention is to provide a pavement structure analysis method to address the deficiencies of the existing technology, which can be applied to the pavement structure design under different load conditions and improve the accuracy of pavement structure design.

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

[0007] A pavement structure analysis method, which adjusts the type and / or thickness of each pavement structure layer to make the pavement structure meet the requirements of the pavement structure design limit state equation;

[0008] The expression of the limit state equation of pavement structure design is as follows:

[0009] γ r (σ pr +σ tr )≤f

[0010] In the above formula, σ pr =k r k f k c σ ps ,

[0011]

[0012] Among them, γ r is the importance coefficient of the pavement structure, f is the standard value of the pavement flexural strength, σ pr is the fatigue stress of the surface plate caused by the design axial load at the critical load position of the surface plate, σ tr is the temperature fatigue stress, σ ps k is the surface plate load stress generated by the design axial load at the critical load position of the four-side free plate, r is the stress reduction factor, k c is the comprehensive coefficient, k f is the load fatigue stress coefficient, φ is the surface stress coefficient of the standard size plate at the critical load position, k L is the plate length correction factor for load stress of non-standard size plates, a is the equivalent load radius of double wheel load on one side, P s is the design axial load, L is the length of the surface plate, α L , β L is the regression coefficient of the plate length correction factor, l g is the equivalent relative stiffness radius of the double-layer plate when calculating the load stress, k is the axis type, q s is the ground pressure of the design axle load, d s It has a double wheelbase.

[0013] This method calculates load fatigue stress based on uniaxial and biaxial design loads under different load conditions. The results are more accurate and provide a basis for designing road pavement structures under different load conditions. This method is applicable to pavement structure design under different load conditions, better reflecting and meeting pavement load characteristics and engineering requirements.

[0014] Furthermore, for cement concrete pavement: f=f r ,

[0015] Steel fiber concrete pavement: f=(1+R e.300 )f fr ,

[0016]

[0017] Among them, f r is the standard value of the flexural tensile strength of cement concrete, f fr is the standard value of flexural tensile strength of steel fiber concrete, R e.300 is the post-crack bending toughness ratio of the steel fiber reinforced concrete beam when the mid-span deflection is 1 / 300 of the beam length, N e is the cumulative number of times the design axle load acts at the critical load position within the design service life, a f 、b f is the shape and strength parameter of steel fiber concrete, λ f is the characteristic value of steel fiber content, and θ' is the material fatigue index.

[0018] Furthermore, when the dual rear axles are designed for axle load, the expression for the cumulative number of times the design axle load acts at the critical load position within the design service life is as follows:

[0019]

[0020] Among them, f e is the lane coefficient, η e is the lateral distribution coefficient of the vehicle wheel track, P s is the design axle load, α k is the axle load coefficient of type k, k is the axle type, k = 1 is a single rear axle, k = 2 is a double rear axle, k = 3 is a rear three axle, N 100 The number of times the social traffic on the road that also serves as a local highway is converted into the design lane to withstand the 100KN single-axle double-wheel design axle load, n i is the number of transports by the i-th transport vehicle; P i,k is the representative axle load of the kth axle type of the i-th transport vehicle, and m is the number of transport vehicle types.

[0021] Furthermore, when the 100kN single-axle double-wheel load is the design axle load, the expression for the cumulative number of times the design axle load acts at the critical load position within the design service life is as follows:

[0022] N e =f e η e N s +N 100

[0023]

[0024] Among them, f e is the lane coefficient, η e is the lateral distribution coefficient of the vehicle wheel track, k is the axle type, k = 1 is a single rear axle, k = 2 is a double rear axle, k = 3 is a rear three axle, N 100 The number of times the social traffic on the road that also serves as a local highway is converted into the design lane to withstand the 100KN single-axle double-wheel design axle load, n i is the number of transports by the i-th transport vehicle; P i,k is the representative axle load of the kth axle type of the i-th transport vehicle, and m is the number of transport vehicle types.

[0025] Furthermore, the expression of the surface stress coefficient of the standard size plate at the critical load position is as follows:

[0026]

[0027] Among them, D c 、D b are the cross-sectional bending stiffness of the surface plate and the base plate, M cb is the total bending moment coefficient of the double-layer plate at the critical load position, is the moment distribution coefficient of the surface plate, h c is the thickness of the surface plate, d and e are the regression coefficients of the bending moment distribution coefficient, k v 、k v0 are the vertical spring coefficients between layers of the double-layer plate with and without interlayer, respectively.

[0028] Furthermore, the expression for the total bending moment coefficient of the double-layer plate at the critical load position is as follows:

[0029]

[0030] Among them, A, B, and C are the regression coefficients of the bending moment coefficient, a is the equivalent load radius of the double wheel load on one side, l g is the equivalent relative stiffness radius of the double-layer plate when calculating load stress.

[0031] Furthermore, the expression of temperature fatigue stress is as follows:

[0032]

[0033] Among them, α c is the linear expansion coefficient of concrete, T g.r is the fatigue temperature gradient of the benchmark pavement structure, E c is the elastic modulus of the surface layer, h c is the thickness of the surface layer, ξ t is the fatigue temperature gradient correction factor of the non-reference pavement structure, C L is the temperature warping stress coefficient at the middle of the longitudinal edge.

[0034] Furthermore, the fatigue temperature gradient correction coefficient of the non-reference pavement structure is expressed as follows:

[0035]

[0036] Among them, E c is the elastic modulus of the surface layer, h c is the thickness of the surface layer, f r is the standard value of flexural tensile strength of cement concrete, C L is the temperature warping stress coefficient at the middle of the longitudinal edge.

[0037] Based on the same inventive concept, the present invention further provides an electronic device, comprising:

[0038] one or more processors;

[0039] A memory having one or more programs stored thereon, which, when executed by the one or more processors, enables the one or more processors to implement the steps of the pavement structure analysis method.

[0040] Based on the same inventive concept, the present invention further provides a computer-readable storage medium storing a computer program, which implements the steps of the pavement structure analysis method when executed by a processor.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention establishes a calculation method for the cumulative number of axle load actions based on biaxial and uniaxial design axle loads, providing a basis for the design of road pavement structures under different load conditions.

[0043] The load fatigue stress is calculated based on the uniaxial and biaxial design load axes under different load conditions. The load fatigue stress calculation results are more accurate and can be applied to the pavement structure design under different load conditions, better reflecting and meeting the pavement load characteristics and engineering requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1is a schematic flow chart of the pavement structure design method of the present invention;

[0045] Figure 2 It is a schematic diagram of the double rear axle structure;

[0046] Figure 3 It is a schematic diagram of the rear three-axle structure;

[0047] Figure 4 Schematic diagram of the rear five-axis structure. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the following embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appearing below merely indicate the directions of upper, lower, left, and right relative to the accompanying drawings and do not limit the structure.

[0049] Example 1

[0050] In view of the fact that the current pavement structure design method for hydropower and water conservancy project roads does not fully consider the special road load conditions and functional requirements of hydropower and water conservancy project roads, this embodiment proposes a pavement structure design method for hydropower and water conservancy project roads from the aspects of pavement structure design working life, cumulative design axle load action times, pavement structure combination design, load fatigue stress calculation, temperature fatigue stress calculation, pavement structure limit state and verification standards, design parameters, etc. The method can be applied to pavement structure design under different load conditions, and better reflect and meet the pavement load characteristics and engineering requirements of hydropower and water conservancy project roads.

[0051] like Figure 1 The hydropower and water conservancy project road pavement structure design method of this embodiment includes the following steps:

[0052] Step 1: Collect road profile information.

[0053] Determine the natural zoning of the road location, road grade, pavement width, road properties, pavement design service life, and local fatigue temperature gradient.

[0054] When it is a temporary road, the design working life of the pavement is the same as the construction period of the hydropower and water conservancy project; when it is a permanent road, the design working life takes into account factors such as road grade and surface type, and is determined according to Table 1.

[0055] Table 1 Lower limit of design service life of permanent road pavement

[0056]

[0057] Step 2: Determine traffic load parameters based on traffic survey.

[0058] 2.1) Determine the design axle load based on traffic survey and the cumulative number of actions N of the 100KN single-axle design axle load e Or determine the traffic load level based on the biaxial design axle load.

[0059] 2.2) Calculate the cumulative number of times N the design axle load acts at the critical load position (the middle of the pavement longitudinal joint edge) within the design service life e .

[0060] When double rear axles are used as the design axle load, N e The calculation formula is as follows:

[0061]

[0062] Where: P s is the design axle load; P i,k is the representative axle load of the kth axle type of transport vehicle (k = 1 for a single rear axle, k = 2 for double rear axles, k = 3 for three rear axles); n i is the number of transports by the i-th transport vehicle; N 100 The number of times social traffic on a road that also serves as a local highway converts the load into a 100kN single-axle double-wheel design axle load that the design lane bears according to the "Highway Cement Concrete Pavement Design Code" (JTG D40-2011); N s f is the cumulative number of times the design axle load of the road power station transport vehicle acts within the design service life; e is the lane coefficient, which is 1 for single lane or dual lane, and 0.7 for two-way four lane; e is the lateral distribution coefficient of the vehicle wheel track. When the width of the one-way lane on the road is ≥4m, it is taken as 0.40; when the width of the one-way lane is ≤3.5m, it is taken as 0.70; k The axle type coefficient of the K-type axle type is α2 = 1 for the double rear axle and α3 = 1.5 for the rear three axles. The axle type coefficient α1 for the single axle is: ordinary concrete, reinforced concrete, steel fiber reinforced concrete α1 = 6.71l g -1.84 , RCC α1=4.85l g -1.63 , l g Indicates the equivalent relative stiffness radius (mm) of the double-layer plate when calculating load stress.

[0063] When the design axle load is 100kN, the load of the single-axle double-wheel group is N e The calculation formula is as follows:

[0064] N e =f e η e N s +N 100

[0065]

[0066] Step three: Preliminary design of the pavement structure and determination of parameters of each structural layer.

[0067] The parameters of each structural layer include the type of each structural layer of the pavement, the thickness of each structural layer of the pavement, the elastic modulus of each structural layer of the pavement, the Poisson's ratio of each structural layer of the pavement, the linear expansion coefficient of concrete, the length of the surface layer, the width of the surface layer, the flexural strength of concrete, and the comprehensive rebound modulus of the roadbed top surface.

[0068] The type, thickness, surface plate length and width of each structural layer are customized by the designer. The elastic modulus of each structural layer of the pavement, the Poisson's ratio of each structural layer of the pavement, the linear expansion coefficient of concrete, the comprehensive rebound modulus of the roadbed top surface, etc. are determined in accordance with the "Highway Cement Concrete Pavement Design Code" (JTG D40).

[0069] The standard values ​​of the surface flexural strength required for each traffic level are determined according to Table 2.

[0070] Table 2 Minimum value of standard value of bending tensile strength of surface layer

[0071]

[0072] When roller compacted concrete is used as the base layer, the strength of the roller compacted concrete shall not be less than 2.5MPa.

[0073] Step 4: Calculate load fatigue stress.

[0074] 4.1) Calculation formula for load fatigue stress of concrete pavement generated by repeated action of design axle load σ pr as follows:

[0075] σ pr =k r k f k c σ ps

[0076] Where: σ pr is the fatigue stress of the surface plate caused by the design axle load at the critical load position of the surface plate (the middle of the edge of the longitudinal joint of the pavement) (MPa); ps is the load stress of the surface layer plate generated by the design axle load at the critical load position of the four-side free plate (the middle of the edge of the longitudinal joint of the pavement) (MPa); r is the stress reduction factor that takes into account the effects of joint load transfer and road panel width; when concrete shoulders are used, k r =0.80~0.85 (the lower value is taken when the shoulder surface layer is of the same thickness as the road surface layer, and the higher value is taken when the thickness is reduced); when a flexible shoulder or earth shoulder is used, k r=0.90; if there is a permanent crash barrier on the shoulder side, or the road panel width exceeds 4m, k r =0.75; k c k is a comprehensive coefficient that takes into account the difference between calculation theory and actual conditions as well as the influence of dynamic load and other factors; f Load fatigue stress coefficient to consider the cumulative fatigue effect of load stress within the design service life: When the surface layer (base layer) material is ordinary concrete, reinforced concrete, roller-compacted concrete or lean concrete: When the surface layer (base layer) material is steel fiber concrete:

[0077] R e.300 is the post-crack bending toughness ratio of the steel fiber reinforced concrete beam when the mid-span deflection is 1 / 300 of the beam length, R e.300 It is related to the characteristic value of steel fiber content, as well as the shape and strength of the steel fiber end, and is determined by experiments; θ' is the material fatigue index, θ'=0.057 for ordinary concrete, reinforced concrete, and steel fiber concrete, and θ'=0.065 for roller-compacted concrete; a f 、b f is a parameter related to the shape and strength of steel fiber concrete, determined through experiments; f is the characteristic value of steel fiber content, λ f =ρ f l f / d f ρ f 、l f d f are the volume ratio (%), length (mm), and diameter (mm) of the steel fiber respectively.

[0078] The four-side free board has the standard size of 5m in length and 3.75m in width.

[0079] Comprehensive coefficient k considering the difference between calculation theory and actual situation and the influence of factors such as dynamic load c Determine according to Table 3.

[0080] Table 3 Comprehensive coefficient k of theoretical deviation and dynamic load influence c

[0081]

[0082] 4.2) Load stress σ of a plate with four free edges ps The calculation formula is as follows:

[0083] σ ps =P s k L φ

[0084]

[0085]

[0086] Where: P s is the design axial load (uniaxial or biaxial); φ is the surface stress coefficient of the standard size (5.0×3.75m) plate at the critical load position; L is the plate length of the surface layer (m), k L is the plate length correction factor for non-standard size plates; α L , β L is the regression coefficient of the plate length correction factor, determined according to Table 4; a is the equivalent load radius of double wheel load on one side (mm).

[0087] E c 、h c are the elastic modulus (MPa) and thickness (m) of the surface layer; E b 、h b are the elastic modulus (MPa) and thickness (m) of the base plate; D c 、D b are the cross-sectional bending stiffness of the surface plate and the base plate (MPa×m 3 ), Here i is c, b. i is the Poisson's ratio of the surface layer or base layer, ν c is the Poisson's ratio of the surface plate, ν b is the Poisson's ratio of the base plate.

[0088] M cb is the total bending moment coefficient of the double-layer plate at the critical load position; is the bending moment distribution coefficient of the surface plate; d and e are the regression coefficients of the bending moment distribution coefficient of the pavement structure, determined according to Table 4; k v 、k v0 are the vertical spring coefficients between the layers of the double-layer plate with and without interlayer (MN / m); E 3c 、h 3c are the elastic modulus (MPa) and thickness (m) of the interlayer between the double-layer plates, respectively.

[0089] The above mentioned pavement structure bending moment coefficient M at different critical load positions cb The calculation formula is as follows:

[0090]

[0091] Where: P s is the design axle load (single or double axis); q s is the ground pressure of the design axle load (MPa), which is obtained through actual measurement. When there is no actual measurement data, the design double axle load P s When <270kN, take q s =0.7MPa, P s =270~450kN, take qs =0.9MPa, design shaft load P s When >450kN, take q s =1.20MPa; 100kN uniaxial load, take q s =0.572MPa.

[0092] d s is the double wheelbase, which can generally be taken as 0.34m; a is the equivalent load radius of double wheel load on one side (mm); k is the axle type, k=1 is a single rear axle, k=2 is a double rear axle, and k=3 is a rear three axle.

[0093] l g The equivalent relative stiffness radius (mm) of a double-layer plate when calculating load stress; when it is a single-layer plate, it is changed to the relative stiffness radius of the single-layer plate r c (m), still calculated according to the above formula, take D b =0, k v →∞.

[0094] E t 、v t are the equivalent rebound modulus (MPa) and Poisson's ratio of the slab bottom foundation respectively; A, B, and C are the regression coefficients of the bending moment coefficient of the pavement structure, determined according to Table 4.

[0095] Table 4 Pavement structure bending moment regression coefficients A, B, C, d, e

[0096]

[0097] Equivalent rebound modulus E of the top surface of the granular layer of the newly built highway t The calculation formula is as follows:

[0098]

[0099] η=0.86+0.26lnh x

[0100] Where: E0 is the comprehensive rebound modulus of the roadbed top (MPa); η' is the total thickness of the granular layer h x The relevant regression coefficient; E x is the equivalent rebound modulus of the granular layer (MPa): h x is the total thickness of the granular layer (m): n is the number of granular layers; E i 、h i is the resilience modulus (MPa) and thickness (m) of the i-th granular structural layer.

[0101] Step 5: Calculate the temperature fatigue stress.

[0102] The temperature fatigue stress σ of the single-layer ply or the upper layer of the double-layer ply at the critical load position within the design service life of the pavement structure tr The calculation formula is as follows:

[0103]

[0104] Where: α c is the linear expansion coefficient of concrete (℃ -1 );T g.r is the fatigue temperature gradient of the benchmark pavement structure (℃ / m); f C is the temperature warping stress coefficient at the midpoint of the beam; ξ t is the fatigue temperature gradient correction factor for non-reference pavement structures (reference pavement structures: h c =0.22m, E c =31000MPa,α c =1×10 -5 ℃ -1 , f r = infinite plate with a pressure of 5 MPa); L is the length of the surface plate (m).

[0105] r g.t To calculate the bending stiffness radius of the double-layer plate relative to the roadbed when calculating temperature stress (m): When it is a single-layer plate, it is changed to the bending stiffness radius r of the single-layer plate relative to the roadbed c,t , still calculate according to this formula, take D b =0.

[0106] ζ is a parameter related to the double-layer plate structure: For a single-layer plate, ζ=0.

[0107] r β is the interlayer contact parameter (m):

[0108] k v.t is the vertical contact stiffness between the surface layer and the base layer (MPa / m), when there is no asphalt interlayer, For calculation, when there is asphalt interlayer, take 3000MPa / m.

[0109] C L is the temperature warping stress coefficient at the middle of the longitudinal edge.

[0110] Step six: determine whether the type and thickness of the initially proposed pavement structure meet the requirements of the pavement structure limit state equation.

[0111] The structural design limit state equations for cement concrete pavement, reinforced concrete pavement, and roller-compacted concrete pavement are as follows:

[0112] γ r (σpr +σ tr )≤f r

[0113] The limit state equation for the design of steel fiber concrete pavement structure is as follows:

[0114] γ r (σ pr +σ tr )≤(1+R e.300 )f fr

[0115] Where: f r is the standard value of flexural tensile strength of cement concrete (MPa); f fr is the standard value of the initial crack strength of steel fiber concrete (MPa); R e.300 is the post-crack bending toughness ratio of the steel fiber reinforced concrete beam when the mid-span deflection is 1 / 300 of the beam length; r is the pavement structure importance coefficient.

[0116] Pavement structure importance coefficient γ r Determine according to Table 5.

[0117] When using large equipment such as slipform pavers for construction, the pavement structure importance coefficient shall be taken as the lower limit of the range in Table 5; when using small equipment for construction, the pavement structure importance coefficient shall be taken as the upper limit of the range in Table 5; temporary roads can be used at a lower level, and roads that also serve as local highways can be used at a higher level.

[0118] Table 5 Pavement structure importance coefficient γ r

[0119]

[0120] When the pavement structure limit state equation is not satisfied, it is necessary to adjust the structural layer thickness or the pavement structure type, such as thickening / reducing the thickness of a certain structural layer, changing the pavement structure type, and return to step three until the pavement structure limit state equation is satisfied.

[0121] Fatigue temperature gradient, load fatigue stress coefficient, etc. are quoted from "Highway Cement Concrete Pavement Design Code" (JTG3340) (Draft for Comments).

[0122] The load stress and temperature fatigue stress of the surface slab are supplemented and improved based on the "Highway Cement Concrete Pavement Design Code" (JTG 3340) (Draft for Comments) and combined with the road load characteristics of hydropower and water conservancy projects. It is applicable to the load stress calculation of biaxial and uniaxial design axle loads under different load conditions.

[0123] This method establishes a calculation method for the cumulative number of axle load actions based on biaxial and uniaxial design axle loads, and calculates load fatigue stress according to the biaxial and uniaxial design axle loads under different load conditions, making the load fatigue stress calculation results more accurate and providing a basis for the design of road pavement structures under different load conditions.

[0124] This method proposes a design method for cement concrete pavement structure of hydropower and water conservancy project roads based on the design service life of pavement structure, pavement structure combination design, load fatigue stress calculation, temperature fatigue stress calculation, pavement structure limit state and verification standard, design parameters, etc. It can be applied to the pavement structure design under different load conditions, and better reflect and meet the load characteristics and engineering requirements of hydropower and water conservancy project roads.

[0125] Example 2

[0126] In this embodiment, a concrete road in a certain hydropower station is used as an example for specific calculation. The specific steps are as follows:

[0127] Step 1: Collect road profile information.

[0128] The natural zone is VII, with no frozen soil. The road grade is the main secondary road on site, with a road width of 8m (two lanes in both directions). The road nature is a permanent road, with a designed working life of 20 years and a fatigue temperature gradient of 42℃ / m.

[0129] Step 2: Determine traffic load parameters based on traffic survey.

[0130] 2.1) Determine the design axle load and traffic load level

[0131] The main cargo transported by road is gravel and slag, with a total transport volume of 4.0949 million tons, and the transport vehicles are double rear axle dump trucks.

[0132] The average loading capacity of a double rear axle dump truck is 32t, and the number of transports is 4,094,900t / 32t = 127,965 times.

[0133] The vehicle weight of a double rear axle dump truck is 12.5t, and the total vehicle weight is 12.5+32=44.5t. According to Table 6, the total weight axle load coefficient of the double rear axles is 0.82, and the average axle load of the double rear axles is 44.5t×0.82=364KN.

[0134] The rear axle unevenness correction coefficient of the double rear axle dump truck is 1. According to Table 7, the guarantee rate coefficient representing the axle load is 1.04, and the representative axle load is 1×1.04×364KN=378kN.

[0135] From now on, double axles are used as the design axle type, and the design axle load is 378KN. According to Table 8, the traffic load level is heavy.

[0136] Table 6 Axle load factors of different vehicle models

[0137]

[0138] Table 7 Guarantee coefficients of representative axle loads of various vehicles

[0139]

[0140] Table 8 Traffic classification range

[0141]

[0142] 2.2) Calculate the cumulative number of times N the design axle load acts at the critical load position (the middle of the pavement longitudinal joint edge) within the design service life e .

[0143] Double rear axle type k=2,α2=1,the cumulative number of times the design axle load of the power station transport vehicle acts within the design service life The cumulative number of times N the design axle load of social traffic acts 100 =0.

[0144] Lane coefficient f e =1, vehicle wheel track lateral distribution coefficient η e =0.4, the cumulative number of times the design axle load acts at the critical load position within the design service life

[0145] Step 3: Preliminary design of the pavement structure and determination of the parameters of each structural layer, as shown in Table 9.

[0146] Table 9 Preliminary pavement structure and material parameters

[0147]

[0148] Concrete linear expansion coefficient α c =10×10 -6 / ℃, the surface layer board is 5m long, 4m wide, the standard value of the flexural tensile strength of cement concrete is 5.5Mpa, and the initial surface layer thickness is 25cm.

[0149] Step 4: Calculate load fatigue stress.

[0150] Bending stiffness of surface layer D c =43.96MN×m, equivalent base bending stiffness D b =8.33MN×m, equivalent bending stiffness of the surface layer D c +D b =52.29MN×m.

[0151] Vertical spring coefficient between layers of double-layer plate kv0 =33846MN / m.

[0152] Stiffness radius of equivalent surface plate l g =0.910m.

[0153] Double wheel equivalent load circle radius Among them, the axis type k=2.

[0154] Total bending moment coefficient of pavement structure Among them, A=0.049, B=0.434, and C=-0.174.

[0155] Moment distribution coefficient of the surface plate Where d = 0.696, e = 0.846.

[0156] Plate length correction factor where α L =0.9, β L =1.2.

[0157] The surface stress coefficient of the standard size (5.0×3.75m) plate at the critical load position is:

[0158] Regression coefficient of granular layer:

[0159] η=0.86+0.26lnh x =0.442

[0160] Equivalent rebound modulus of the top surface of the granular layer:

[0161]

[0162] Load stress of a plate with four free sides

[0163] Load fatigue stress coefficient within the design service life of the pavement structure Where θ' = 0.057.

[0164] Stress reduction factor k considering the effects of joint load transfer and road slab width r =0.8.

[0165] Comprehensive coefficient k considering the difference between calculation theory and actual situation and the influence of factors such as dynamic load c =1.02.

[0166] Load fatigue stress σ generated by repeated action of design axle load on concrete pavement pr =k r k f k c σ ps=3.77MPa.

[0167] Step 5: Calculate the warm fatigue stress.

[0168] Bending stiffness radius of the double-layer plate relative to the roadbed when calculating temperature stress

[0169] Thermal warping stress coefficient C at the middle of the longitudinal edge L Calculate as follows:

[0170]

[0171] C L =0.790.

[0172] The temperature internal stress and thickness correction coefficient of non-reference pavement structure are as follows:

[0173]

[0174] ξ t =0.718.

[0175] Fatigue temperature stress of concrete panels

[0176] Step six: determine whether the type and thickness of the initially proposed pavement structure meet the requirements of the pavement structure limit state equation.

[0177] Pavement structure importance coefficient γ r =1.1,γ r (σ pr +σ tr )=5.23MPa,f r =5.50MPa.

[0178] From the above, we can see that γ r (σ pr +σ tr )≤f r , meeting the pavement structure limit state equation, the initially proposed pavement structure layer and thickness meet the requirements.

[0179] Example 3

[0180] This embodiment provides an electronic device, including:

[0181] one or more processors;

[0182] The memory stores one or more programs, which, when executed by one or more processors, enable the one or more processors to implement the steps of the pavement structure analysis method.

[0183] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk storage.

[0184] In other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors, which are not limited herein.

[0185] This embodiment provides a computer-readable storage medium storing a computer program, which implements the steps of the pavement structure analysis method when executed by a processor.

[0186] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

Claims

1. A pavement structure analysis method, characterized in that: By adjusting the type and / or thickness of each structural layer of the pavement, the pavement structure can meet the requirements of the limit state equation of the pavement structure design; The expression of the limit state equation of pavement structure design is as follows: c r (s pr +s tr )≤f In the above formula, σ pr =k r k f k c σ ps , Among them, γ r is the importance coefficient of the pavement structure, f is the standard value of the pavement flexural strength, σ pr is the fatigue stress of the surface plate caused by the design axial load at the critical load position of the surface plate, σ tr is the temperature fatigue stress, σ ps k is the surface plate load stress generated by the design axial load at the critical load position of the four-side free plate, r is the stress reduction factor, k c is the comprehensive coefficient, k f is the load fatigue stress coefficient, φ is the surface stress coefficient of the standard size plate at the critical load position, k L is the plate length correction factor for load stress of non-standard size plates, a is the equivalent load radius of double wheel load on one side, P s is the design axial load, L is the length of the surface plate, α L , β L is the regression coefficient of the plate length correction factor, l g is the equivalent relative stiffness radius of the double-layer plate when calculating the load stress, k is the axis type, q s is the ground pressure of the design axle load, d s It has a double wheelbase.

2. The pavement structure analysis method according to claim 1, characterized in that: Cement concrete pavement: f=f r , Steel fiber concrete pavement: f=(1+R e.300 )f fr , Among them, f r is the standard value of the flexural tensile strength of cement concrete, f fr is the standard value of flexural tensile strength of steel fiber concrete, R e.300 is the post-crack bending toughness ratio of the steel fiber reinforced concrete beam when the mid-span deflection is 1 / 300 of the beam length, N e is the cumulative number of times the design axle load acts at the critical load position within the design service life, a f 、b f is the shape and strength parameter of steel fiber concrete, λ f is the characteristic value of steel fiber content, and θ' is the material fatigue index.

3. The pavement structure analysis method according to claim 2, characterized in that: When the double rear axles are designed for axle load, the expression for the cumulative number of times the design axle load acts at the critical load position within the design service life is as follows: Among them, f e is the lane coefficient, η e is the lateral distribution coefficient of the vehicle wheel track, P s is the design axle load, α k is the shaft load factor of type k shaft, k is the shaft type, N 100 The number of times the social traffic on the road that also serves as a local highway is converted into the design lane to withstand the 100KN single-axle double-wheel design axle load, n i is the number of transports by the i-th transport vehicle; P i,k is the representative axle load of the kth axle type of the i-th transport vehicle, and m is the number of transport vehicle types.

4. The pavement structure analysis method according to claim 2, characterized in that: When the 100kN single-axle double-wheel load is the design axle load, the expression for the cumulative number of times the design axle load acts at the critical load position within the design service life is as follows: N e =f e or e N s +N 100 Among them, f e is the lane coefficient, η e is the lateral distribution coefficient of the vehicle wheel track, k is the axle type, N 100 The number of times the social traffic on the road that also serves as a local highway is converted into the design lane to withstand the 100KN single-axle double-wheel design axle load, n i is the number of transports by the i-th transport vehicle; P i,k is the representative axle load of the kth axle type of the i-th transport vehicle, and m is the number of transport vehicle types.

5. The pavement structure analysis method according to claim 1, characterized in that: The expression of the surface stress coefficient of the standard size plate at the critical load position is as follows: Among them, D c 、D b are the cross-sectional bending stiffness of the surface plate and the base plate, M cb is the total bending moment coefficient of the double-layer plate at the critical load position, is the moment distribution coefficient of the surface plate, h c is the thickness of the surface plate, d and e are the regression coefficients of the bending moment distribution coefficient, k v 、k v0 are the vertical spring coefficients between layers of the double-layer plate with and without interlayer, respectively.

6. The pavement structure analysis method according to claim 5, characterized in that: The expression of the total bending moment coefficient of the double-layer plate at the critical load position is as follows: Among them, A, B, and C are the regression coefficients of the bending moment coefficient, a is the equivalent load radius of the double wheel load on one side, l g is the equivalent relative stiffness radius of the double-layer plate when calculating load stress.

7. The pavement structure analysis method according to claim 1, characterized in that: The expression of temperature fatigue stress is as follows: Among them, α c is the linear expansion coefficient of concrete, T g.r is the fatigue temperature gradient of the benchmark pavement structure, E c is the elastic modulus of the surface layer, h c is the thickness of the surface layer, ξ t is the fatigue temperature gradient correction factor of the non-reference pavement structure, C L is the temperature warping stress coefficient at the middle of the longitudinal edge.

8. The pavement structure analysis method according to claim 7, characterized in that: The expression of the fatigue temperature gradient correction coefficient of non-reference pavement structure is as follows: Among them, f r It is the standard value of flexural tensile strength of cement concrete.

9. An electronic device, characterized in that: include: one or more processors; A memory having one or more programs stored thereon, which, when executed by the one or more processors, enables the one or more processors to implement the steps of the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that The computer program is stored therein, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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