Method for coordinating rigidity difference between paving system and lower bearing structure

Abstract

A method for coordinating the rigidity difference between a paving system and a lower bearing structure comprises the following steps that S1, a target paving structure combination is preliminarily planned, specifically, on the basis of an original datum paving structure, a rigidity transition layer is additionally arranged between a surface paving system and the lower bearing structure, and a rigidity transition paving structure is constructed; the rigidity transition pavement structure comprises a surface pavement system, a rigidity transition layer and a lower bearing structure from top to bottom. S2, according to the target pavement structure combination, establishing a rigidity transition pavement structure mechanical model; s3, designing a response curved surface analysis test according to the mechanical model of the rigidity transition pavement structure to obtain a final response curved surface model; and S4, according to the final response curved surface model, target pavement structure parameters are drawn up. Rigidity transition of an inner surface paving system of the paving structure and a lower bearing structure of the paving structure can be achieved, the rigidity difference is coordinated, and the stress level of the paving structure is reduced.

Description

Technical Field

[0001] The invention relates to coordinating the difference in stiffness between a paving system and an underlying structure, and in particular to a method for coordinating the difference in stiffness between a paving system and an underlying structure. Background Art

[0002] The pavement structure consists of a surface pavement system and a supporting structure. It is a common structural combination in engineering, such as multi-layer flexible pavement, airport pavement, and multi-layer foundation pavement. The surface pavement system includes one, two, or three layers, and the outermost layer is the surface pavement layer. The supporting structure plays an important role in connecting the upper and lower parts of the pavement structure and diffusing the traffic load. Therefore, the stiffness of the supporting structure affects the mechanical behavior mode of the entire pavement structure.

[0003] Depending on the materials used, the modulus of the underlying structure varies greatly: some are only a few hundred megapascals, while others can reach tens of thousands of megapascals. According to the mechanics theory of layered elastic systems, different pavement system-underlying structure stiffness combinations will result in very different overall force modes for the pavement structure: when the modulus of the underlying structure is high and the stiffness is large, the underlying structure will bear most of the external force load, and the surface pavement system is in a compressive state, and the stress level of the underlying structure is high; when the modulus of the underlying structure is low and the stiffness is small, the pavement system will mainly bear bending and tension, and the bearing requirements for the underlying structure will also be greatly increased.

[0004] On the other hand, the stiffness difference between the surface pavement system and the underlying structure will also have a significant impact on the mechanical response characteristics of a single structural layer: when the stiffness of the underlying structure is large, the increase in the stiffness difference between the surface pavement system and the underlying structure will increase the shear stress level of the surface pavement system; when the stiffness of the underlying structure is small, the stiffness difference between the surface pavement system and the underlying structure will have an adverse effect on the bending and tensile stress of the surface pavement system. It can be seen that the influence of the internal stiffness combination of the pavement structure on the internal stress condition of the structure is very complex, and the coordination of the stiffness combination plays a key role in reducing the excessive concentration of stress in the pavement structure on a certain indicator and improving the durability of the pavement structure. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a method for coordinating the stiffness difference between the pavement system and the underlying structure, which can achieve the stiffness transition between the pavement system on the inner surface of the pavement structure and its underlying structure, coordinate their stiffness differences, and reduce the stress level of the pavement structure.

[0006] The technical solution adopted by the present invention to solve the technical problem is a method for coordinating the stiffness difference between the paving system and the underlying structure, comprising the following steps:

[0007] Step S1: Preliminary target pavement structure combination: on the basis of the original reference pavement structure, a stiffness transition layer is added between the surface pavement system and the underlying structure to construct a stiffness transition pavement structure; the stiffness transition pavement structure includes the surface pavement system, the stiffness transition layer and the underlying structure from top to bottom;

[0008] Step S2, establishing a stiffness transition pavement structure mechanical model according to the target pavement structure combination;

[0009] Step S3: designing a response surface analysis experiment based on the stiffness transition pavement structure mechanical model to obtain the final response surface model;

[0010] Step S4: According to the final response surface model, the target pavement structure parameters are formulated.

[0011] Further, in step S1, the original reference paving structure is a semi-rigid base asphalt pavement structure.

[0012] Further, in step S1, the stiffness transition pavement structure includes, from top to bottom, a surface pavement system, a stiffness transition layer, a first lower supporting structure, a second lower supporting structure, and a third lower supporting structure.

[0013] Furthermore, the surface paving system is an asphalt surface layer, the first supporting structure is a first cement-stabilized gravel base layer, the second supporting structure is a second cement-stabilized gravel base layer, and the third supporting structure is a cement-stabilized soil layer.

[0014] Further, in step S2, the standard lane width in the driving direction is used as the length, the standard lane width perpendicular to the driving direction is used as the width, and the value in the depth direction that is not less than the roadbed working area is used as the height to construct a cubic model. The cubic model is divided into an asphalt surface layer, a rigidity transition layer, a first cement-stabilized gravel base layer, a second cement-stabilized gravel base layer, a cement-stabilized soil layer, and a soil base layer from top to bottom; the thickness of each structural layer is: an asphalt surface layer of to-be-determined thickness x1, a rigidity transition layer of to-be-determined thickness x2, and the thickness of the remaining structural layers is consistent with the original semi-rigid base asphalt pavement structure.

[0015] Furthermore, in the mechanical model of the stiffness transition pavement structure, the thickness of the surface pavement system is consistent with the original reference pavement structure, the thickness of the stiffness transition layer is consistent with the surface pavement system, and the thickness of the underlying structural layer is consistent with the original reference pavement structure; the initial material characteristics of each structural layer are as follows: the material parameters of the surface pavement system are consistent with the original reference pavement structure, the material parameters of the stiffness transition layer are the same as the surface pavement system, and the material parameters of the underlying structural layer are the same as those of the original reference pavement structure.

[0016] Further, in step S3, the designed response surface test takes the maximum shear stress y of the surface paving system / rigidity transition layer as the output variable, and the input variables are the surface paving system thickness x1, the stiffness transition layer thickness x2 and the ratio of the stiffness transition layer modulus to the surface paving system modulus x3, referred to as the modulus ratio. Each input variable factor takes three levels: high, medium and low. The response surface analysis test adopts the Box-Behnken design method. According to the set response surface analysis test, the shear stress of the surface paving system, the shear stress of the stiffness transition layer and the maximum shear stress are calculated, wherein the maximum shear stress = MAX (shear stress of the surface paving system, shear stress of the stiffness transition layer), with the goal of reducing the shear stress level of the surface paving system and the stiffness transition layer, so that τ max =MAX (surface paving system shear stress, stiffness transition layer shear stress) minimum;

[0017] Assume y is the output variable τ max , and the input variables surface paving system thickness x1, stiffness transition layer thickness x2, stiffness transition layer and surface paving system modulus ratio x3 have the following relationship:

[0018] y=f(x1,x2,x3)+ε (1)

[0019]

[0020] Where: ε is a random variable or random error, β0 is a constant; x i 、x j are input variables, i=1,2,3, j=1,2,3, β i For x i The linear effect coefficient of ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient of

[0021] When the test area is close to or in the optimal area, there is a nonlinear relationship between the response value and the factors. The maximum shear stress data are fitted to obtain the final response surface model.

[0022] Further, in step S3, the response surface model is:

[0023] τ max =β0+β1x1+β2x2+β3x3+β 12 x1x2+β 13 x1x3+β 23 x2x3+β 11 x1 2 +β 22 x2 2+β 33 x3 2 (3)

[0024] Where: τ max is the maximum shear stress, β0, β1, β2, β3, β 12 , β 13 , β 23 , β 11 , β 22 , β 33 is the coefficient, x1 is the thickness of the surface paving system, x2 is the thickness of the stiffness transition layer, and x3 is the modulus ratio.

[0025] Furthermore, β0=0.317103, β1=0.014573, β2=0.001061, β3=-0.006306, β 12 =0,β 13 =0.000508, β 23 =0,β 11 =-0.000475, β 22 =-0.000022, β 33 =0.

[0026] Further, in step S4, the method for formulating the target paving structure parameters is:

[0027] Formula (3) can be expressed in matrix form as:

[0028] Y=β0+Xb T +XBX T (4)

[0029]

[0030] Where: β0 is a constant; X = (x1, x2, x3); b = (β1, β2, β3), β i For x i The linear effect coefficient, i = 1, 2, 3; B is a k-order symmetric matrix, β ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient of

[0031] Take the first-order derivative of the variables x1, x2, and x3 in equation (4) respectively. If the response can reach the optimal point, then the response value has an extreme point in the variable interval, satisfying:

[0032]

[0033] Formula (6) is a three-term linear equation system including x1, x2, and x3. The solution of formula (6), namely X0, is a stable point. The stable point X0 is expressed as:

[0034]

[0035] Finally, the target pavement structure parameters under the optimal critical mechanical response level are obtained through equations (4) to (7); when there is no stable point X0, that is, when the solution of equation (6) is not within the variable value range, the minimum point of the critical mechanical response within the variable value range is calculated, and the solution of the independent variables x1, x2, and x3 corresponding to the minimum point is the target pavement structure parameter under the required minimum critical mechanical response level.

[0036] Compared with the prior art, the advantages of the present invention are as follows:

[0037] (1) The present invention sets a stiffness transition layer in the pavement structure, which can achieve stiffness transition between the pavement system on the inner surface of the pavement structure and its underlying structure, coordinate their stiffness differences, and reduce the stress level of the pavement structure.

[0038] (2) The present invention adopts the response surface method to solve the problem of nonlinear mechanical response data processing. When the mechanical response data is affected by multiple variables, the interaction of multiple variables on the mechanical response data is considered, and a polynomial model is used to fit the complex unknown function relationship in a small area to reduce the test cost, improve the test quality, and ultimately find the optimal target paving structure parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the existing semi-rigid base asphalt pavement structure.

[0040] Figure 2 It is a schematic diagram of a stiffness transition pavement structure according to an embodiment of the present invention.

[0041] Figure 3 It is a schematic diagram of the mechanical model of the stiffness transition pavement structure of an embodiment of the present invention.

[0042] Figure 4 is a flow chart of an embodiment of the present invention.

[0043] In the figure, 1 is asphalt surface layer, 2 is the first cement stabilized gravel base layer, 3 is the second cement stabilized gravel base layer, 4 is cement stabilized soil layer, and 5 is stiffness transition layer. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] In this embodiment, the reference paving structure selected when describing a method for coordinating the stiffness difference between the paving system and the underlying structure is a semi-rigid base asphalt pavement structure widely used in my country, such as Figure 1 The semi-rigid base asphalt pavement structure includes from top to bottom an asphalt surface layer 1, a first cement stabilized gravel base 2, a second cement stabilized gravel base 3, and a cement stabilized soil layer 4. The first cement stabilized gravel base 2, the second cement stabilized gravel base 3, and the cement stabilized soil layer 4 constitute a semi-rigid base. The asphalt surface layer of the semi-rigid base asphalt pavement is regarded as a surface paving system, and the semi-rigid base is a lower bearing structure.

[0046] A method for coordinating the stiffness difference between the paving system and the underlying structure proposed in the present invention is used to construct a semi-rigid base asphalt pavement structure with a transition in stiffness, aiming to solve the stiffness mutation problem between the flexible surface layer and the semi-rigid base layer in the semi-rigid base asphalt pavement and improve the stress of the paving structure.

[0047] The method of coordinating the stiffness difference between the paving system and the underlying structure in this embodiment includes the following steps:

[0048] Step S1: Preliminary target pavement structure combination: On the basis of the original reference pavement structure, a stiffness transition layer is added between the surface pavement system and the underlying structure to construct a stiffness transition pavement structure, which includes the surface pavement system, stiffness transition layer and underlying structure from top to bottom. The constructed stiffness transition pavement structure is called the target pavement structure.

[0049] like Figure 2 The original reference pavement structure of this embodiment is a semi-rigid base asphalt pavement structure, and the original reference pavement structure includes a surface paving system (asphalt surface layer 1), a first supporting structure (first cement-stabilized gravel base layer 2), a second supporting structure (second cement-stabilized gravel base layer 3), and a third supporting structure (cement-stabilized soil layer 4) from top to bottom. A stiffness transition layer 5 is added between the asphalt surface layer 1 and the first cement-stabilized gravel base layer 2 of the semi-rigid base asphalt pavement structure to construct a stiffness transition pavement structure. The stiffness transition pavement structure includes a surface paving system (asphalt surface layer 1), a stiffness transition layer 5, a first supporting structure (first cement-stabilized gravel base layer 2), a second supporting structure (second cement-stabilized gravel base layer 3), and a third supporting structure (cement-stabilized soil layer 4) from top to bottom.

[0050] Step S2, establishing a stiffness transition pavement structure mechanical model according to the target pavement structure combination;

[0051] According to the initially proposed target pavement structure combination, a mechanical model of the stiffness transition pavement structure is established based on the finite element method, such as Figure 3As shown, the standard lane width in the driving direction is used as the length, the standard lane width perpendicular to the driving direction is used as the width, and the value in the depth direction that is not less than the roadbed work area is used as the height to construct a cube model. The driving load of the cube model is determined according to the actual situation, and generally the single-axle double-wheel load is 0.707Mpa. In this embodiment, the length of the cube model is 3.75m in the driving direction, the width is 3.75m in the vertical driving direction, and the height is not less than the roadbed work area in the depth direction, generally 3m. The driving load parameters are determined according to the traffic conditions. In this embodiment, the driving load is 0.707MPa for a single-axle double-wheel load.

[0052] The cube model is divided into asphalt surface layer, stiffness transition layer, first cement stabilized gravel base, second cement stabilized gravel base, cement stabilized soil layer, and soil base from top to bottom. The thickness of each structural layer is: asphalt surface layer with a to-be-determined thickness of x1, stiffness transition layer with a to-be-determined thickness of x2, and the thickness of the other structural layers is consistent with the reference structural layer. In this embodiment, the thickness of the asphalt surface layer is set to x1, the initial value of the asphalt surface layer thickness is set to 18cm, the thickness of the stiffness transition layer is set to x2, the initial value of the stiffness transition layer thickness is set to 18cm, the thickness of the soil base is set to 2.08m, the cement stabilized soil layer is set to 20cm, the first cement stabilized gravel base is set to 18cm, and the second cement stabilized gravel base is set to 18cm. The modulus of the stiffness transition layer is to be determined, and the material parameters of the other structural layers of the pavement are consistent with the reference structure, as shown in Table 1, and the initial value of the stiffness transition layer modulus is set to 1400MPa.

[0053] Table 1 Mechanical model material parameters

[0054]

[0055]

[0056] In the mechanical model, the initial thickness characteristics of each structural layer are as follows: the thickness of the surface paving system is consistent with the reference structure, the thickness of the stiffness transition layer is consistent with the surface paving system, and the thickness of the underlying structural layer is consistent with the reference structure.

[0057] In the mechanical model, the initial material characteristics of each structural layer are as follows: the material parameters of the surface paving system are consistent with those of the reference structure, the material parameters of the stiffness transition layer are the same as those of the surface paving system, and the material parameters of the underlying structural layer are the same as those of the reference structure.

[0058] Step S3: designing a response surface analysis experiment based on the stiffness transition pavement structure mechanical model to obtain the final response surface model;

[0059] According to the stress characteristics and failure mode of the original pavement structure (reference structure), its key mechanical response is used as the design index of the method for coordinating the stiffness difference between the pavement system and the underlying structure. The key mechanical response is the most unfavorable mechanical response for controlling the failure of the pavement structure. In this embodiment, the maximum shear stress of the selected semi-rigid base asphalt pavement is used as the key mechanical response.

[0060] Reference Figure 4 The response surface test designed in this embodiment takes the maximum shear stress y of the asphalt surface layer / rigidity transition layer as the output variable, and the input variables are the asphalt surface layer thickness x1, the stiffness transition layer thickness x2, and the ratio of the stiffness transition layer modulus to the asphalt surface layer modulus x3 (referred to as modulus ratio). Each input variable factor takes three levels: high, medium, and low, as shown in Table 2. In Table 2, 1 represents a high level, 0 represents a medium level, and -1 represents a low level. In the high level group, the asphalt surface layer thickness x1 takes a value of 12 cm, the stiffness transition layer thickness x2 takes a value of 12 cm, and the modulus ratio x3 takes a value of 6; in the medium level group, the asphalt surface layer thickness x1 takes a value of 9 cm, the stiffness transition layer thickness x2 takes a value of 9 cm, and the modulus ratio x3 takes a value of 4; in the low level group, the asphalt surface layer thickness x1 takes a value of 6 cm, the stiffness transition layer thickness x2 takes a value of 6 cm, and the modulus ratio x3 takes a value of 2. The response surface analysis experiment in this embodiment adopts the Box-Behnken (BBD for short, a type of response surface design) design method, and the values ​​of the response surface experiment design factors are shown in Table 3.

[0061] Table 2 Design factors and level factors

[0062]

[0063] Table 3 Response surface test design factor values

[0064]

[0065] According to the set response surface analysis test, the shear stress of the asphalt surface layer, the shear stress of the stiffness transition layer and the maximum shear stress are calculated, where the maximum shear stress = MAX (asphalt surface layer shear stress, stiffness transition layer shear stress). The shear stress data of the response surface analysis test are shown in Table 4.

[0066] Table 4 Shear stress data of response surface test

[0067]

[0068] The goal is to reduce the shear stress level of the asphalt surface layer and the stiffness transition layer, that is, to comprehensively consider the asphalt surface layer and the stiffness transition layer, so that τ max =MAX(asphalt surface layer shear stress, stiffness transition layer shear stress) is minimum.

[0069] Assume y is the output variable τ max, and the input variables asphalt surface layer thickness x1, stiffness transition layer thickness x2, stiffness transition layer and asphalt surface layer modulus ratio x3 have the following relationship:

[0070] y=f(x1,x2,x3)+ε (1)

[0071]

[0072] Where: ε is a random variable or random error, β0 is a constant; x i 、x j are input variables, i=1,2,3, j=1,2,3, β i For x i The linear effect coefficient of ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient.

[0073] When the test area is close to or in the optimal area, the response value and the factor show a nonlinear relationship. The maximum shear stress data is fitted to obtain the final response surface model. The final response surface model is formula (3):

[0074] τ max =β0+β1x1+β2x2+β3x3+β 12 x1x2+β 13 x1x3+β 23 x2x3+β 11 x1 2 +β 22 x2 2 +β 33 x3 2 (3)

[0075] Where: τ max is the maximum shear stress, β0, β1, β2, β3, β 12 , β 13 , β 23 , β 11 , β 22 , β 33 are coefficients, where β0 = 0.317103, β1 = 0.014573, β2 = 0.001061, β3 = -0.006306, β 12 =0,β 13 =0.000508, β 23 =0,β 11 =-0.000475, β 22 =-0.000022, β 33=0, x1 is the thickness of the asphalt surface layer, x2 is the thickness of the stiffness transition layer, and x3 is the modulus ratio.

[0076] The specific process is: fit the maximum shear stress data to obtain the initial response surface model, perform variance analysis on the initial response surface model to find the significant influencing factors of the model, eliminate non-significant influencing factors, adjust the initial response surface model, and obtain the final response surface model.

[0077] The results of variance analysis are shown in Table 5:

[0078] Table 5 Variance analysis table

[0079]

[0080] From the variance analysis in Table 5, we can see that the F value of the fitting model is 614.73 and the P value is less than 0.05, indicating that the model is significant. 2 , x2 2 All of them are significant model terms. It can be seen that the thickness of the asphalt surface layer, the thickness of the stiffness transition layer, the modulus ratio of the stiffness transition layer to the asphalt surface layer and their interaction are all the maximum shear stress τ of the asphalt surface layer. max Significant influencing factors.

[0081] Step S4: According to the final response surface model, the target pavement structure parameters are formulated;

[0082] Formula (3) can be expressed in matrix form as:

[0083] Y=β0+Xb T +XBX T (4)

[0084]

[0085] Where: β0 is a constant; X = (x1, x2, x3); b = (β1, β2, β3), β i For x i The linear effect coefficient, i = 1, 2, 3; B is a k-order symmetric matrix, β ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient.

[0086] Take the first-order derivative of the variables x1, x2, and x3 in equation (4) respectively. If the response can reach the optimal point, then the response value has an extreme point in the variable interval, satisfying:

[0087]

[0088] Formula (6) is a three-term linear equation system including x1, x2, and x3. The solution of formula (6), namely X0, is a stable point. The stable point X0 is expressed as:

[0089]

[0090] Finally, the target pavement structure parameters under the optimal critical mechanical response level can be obtained through equations (4) to (7). When there is no stable point X0, that is, when the solution of equation (6) is not within the variable value range, the minimum point of the critical mechanical response within the variable value range is calculated, and the solution of the independent variables x1, x2, and x3 corresponding to the minimum point is the target pavement structure parameter under the minimum critical mechanical response level.

[0091] In this embodiment, the target pavement structure parameters obtained are: the thickness of the asphalt surface layer is 6cm, the thickness of the rigid transition layer is 6.8cm, the modulus of the rigid transition layer is 6 times the modulus of the asphalt surface layer, that is, 8400MPa, the cement stabilized soil layer is set to 20cm, the first cement stabilized gravel base is set to 18cm, and the second cement stabilized gravel base is set to 18cm. After calculation, the shear stress of the asphalt surface layer is 0.37MPa, and the shear stress of the rigid transition layer is 0.36MPa. In contrast, when the asphalt surface layer of the semi-rigid base asphalt pavement structure without a rigid transition layer is 12.8cm thick, the maximum shear stress of the asphalt surface layer is 0.43MPa. The shear stress level of the modulus transition semi-rigid base asphalt pavement structure obtained by the method of the present invention is greatly reduced.

[0092] The present invention sets a stiffness transition layer in the pavement structure, which can achieve the stiffness transition between the pavement system on the inner surface of the pavement structure and its underlying structure, coordinate their stiffness differences, and reduce the stress level of the pavement structure. The present invention adopts the response surface method to solve the problem of nonlinear mechanical response data processing. When the mechanical response data is affected by multiple variables, the interaction of multiple variables on the mechanical response data is considered, and a polynomial model is used to fit complex unknown function relationships in a small area to reduce the test cost, improve the test quality, and finally find the optimal target pavement structure parameters.

[0093] The proposed pavement structure thickness parameters do not limit the patent of the present invention. The specific target pavement structure layer parameters and material parameters can be adjusted using the method of the present invention according to the structural combination, material parameters and other influencing factors in the actual benchmark structure.

[0094] Those skilled in the art may make various modifications and variations to the present invention. If these modifications and variations are within the scope of the claims of the present invention and their equivalents, then these modifications and variations are also within the protection scope of the present invention.

[0095] The contents not described in detail in the specification are prior art known to those skilled in the art.

Claims

1. A method for coordinating the stiffness difference between the paving system and the underlying structure, characterized by: The following steps are involved: Step S1: Preliminary target pavement structure combination: on the basis of the original reference pavement structure, a stiffness transition layer is added between the surface pavement system and the underlying structure to construct a stiffness transition pavement structure; the stiffness transition pavement structure includes the surface pavement system, the stiffness transition layer and the underlying structure from top to bottom; Step S2, establishing a stiffness transition pavement structure mechanical model according to the target pavement structure combination; Step S3: designing a response surface analysis experiment based on the stiffness transition pavement structure mechanical model to obtain the final response surface model; Step S4: According to the final response surface model, the target pavement structure parameters are formulated.

2. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 1, characterized in that: In step S1, the original reference paving structure is a semi-rigid base asphalt pavement structure.

3. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 2, characterized in that: In step S1, the stiffness transition pavement structure includes, from top to bottom, a surface pavement system, a stiffness transition layer, a first lower supporting structure, a second lower supporting structure, and a third lower supporting structure.

4. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 3, characterized in that: The surface paving system is an asphalt surface layer, the first underlying structure is a first cement-stabilized gravel base layer, the second underlying structure is a second cement-stabilized gravel base layer, and the third underlying structure is a cement-stabilized soil layer.

5. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 4, characterized in that: In step S2, the standard lane width in the driving direction is used as the length, the standard lane width perpendicular to the driving direction is used as the width, and the value in the depth direction that is not less than the roadbed working area is used as the height to construct a cubic model. The cubic model is divided into an asphalt surface layer, a rigidity transition layer, a first cement-stabilized gravel base layer, a second cement-stabilized gravel base layer, a cement-stabilized soil layer, and a soil base layer from top to bottom; the thickness of each structural layer is: an asphalt surface layer of to-be-determined thickness x1, a rigidity transition layer of to-be-determined thickness x2, and the thickness of the remaining structural layers is consistent with the original semi-rigid base asphalt pavement structure.

6. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 5, characterized in that: In the mechanical model of the stiffness transition pavement structure, the thickness of the surface pavement system is consistent with that of the original reference pavement structure, the thickness of the stiffness transition layer is consistent with that of the surface pavement system, and the thickness of the underlying structural layer is consistent with that of the original reference pavement structure; The initial material characteristics of each structural layer are as follows: the material parameters of the surface paving system are consistent with the original reference paving structure, the material parameters of the stiffness transition layer are the same as the surface paving system, and the material parameters of the underlying structural layer are the same as the original reference paving structure.

7. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 1, characterized in that: In step S3, the designed response surface test takes the maximum shear stress y of the surface paving system / rigidity transition layer as the output variable, and the input variables are the surface paving system thickness x1, the stiffness transition layer thickness x2 and the ratio of the stiffness transition layer modulus to the surface paving system modulus x3, referred to as the modulus ratio. Each input variable factor takes three levels: high, medium and low. The response surface analysis test adopts the Box-Behnken design method. According to the set response surface analysis test, the shear stress of the surface paving system, the shear stress of the stiffness transition layer and the maximum shear stress are calculated, wherein the maximum shear stress = MAX (shear stress of the surface paving system, shear stress of the stiffness transition layer), with the goal of reducing the shear stress levels of the surface paving system and the stiffness transition layer, so that τ max =MAX (surface paving system shear stress, stiffness transition layer shear stress) minimum; Assume y is the output variable τ max , and the input variables surface paving system thickness x1, stiffness transition layer thickness x2, stiffness transition layer and surface paving system modulus ratio x3 have the following relationship: y=f(x1,x2,x3)+ε (1) Where: ε is a random variable or random error, β0 is a constant; x i 、x j are input variables, i=1,2,3, j=1,2,3, β i For x i The linear effect coefficient of ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient of When the test area is close to or in the optimal area, there is a nonlinear relationship between the response value and the factors. The maximum shear stress data are fitted to obtain the final response surface model.

8. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 4, characterized in that: In step S3, the response surface model is: t max =β0+β1x1+β2x2+β3x3+β 12 x1x2+b 13 x1x3+b 23 x2x3+b 11 x1 2 +b 22 x2 2 +b 33 x3 2 (3) Where: τ max is the maximum shear stress, β0, β1, β2, β3, β 12 , β 13 , β 23 , β 11 , β 22 , β 33 is the coefficient, x1 is the thickness of the surface paving system, x2 is the thickness of the stiffness transition layer, and x3 is the modulus ratio.

9. The method for coordinating the stiffness difference between the paving system and the underlying structure as claimed in claim 8, characterized in that: The β0=0.317103, β1=0.014573, β2=0.001061, β3=-0.006306, β 12 =0,β 13 =0.000508, β 23 =0,β 11 =-0.000475, β 22 =-0.000022, β 33 =0.

10. The method for coordinating the stiffness difference between the paving system and the underlying structure according to claim 8, characterized in that: In step S4, the method for formulating the target paving structure parameters is: Formula (3) can be expressed in matrix form as: Y=β0+Xb T +XBX T (4) Where: β0 is a constant; X = (x1, x2, x3); b = (β1, β2, β3), β i For x i The linear effect coefficient, i = 1, 2, 3; B is a k-order symmetric matrix, β ij For x i With x j The linear interaction coefficient between ii For x i The quadratic effect coefficient of Take the first-order derivative of the variables x1, x2, and x3 in equation (4) respectively. If the response can reach the optimal point, then the response value has an extreme point in the variable interval, satisfying: Formula (6) is a three-term linear equation system including x1, x2, and x3. The solution of formula (6), namely X0, is a stable point. The stable point X0 is expressed as: Finally, the target pavement structure parameters under the optimal critical mechanical response level are obtained through equations (4) to (7); when there is no stable point X0, that is, when the solution of equation (6) is not within the variable value range, the minimum point of the critical mechanical response within the variable value range is calculated, and the solution of the independent variables x1, x2, and x3 corresponding to the minimum point is the target pavement structure parameter under the required minimum critical mechanical response level.

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