Roadbed analysis and calculation method considering local deterioration of permafrost roadbed

Abstract

The invention relates to the field of frozen soil roadbed structure calculation, in particular to a roadbed analysis and calculation method considering local deterioration of a permafrost roadbed. According to the method, the diameter D and the height H of a pavement subsidence area are assumed as target subsidence, the position, the size and the deterioration degree of a deterioration area are assumed, numerical analysis is carried out through finite elements or discrete elements, the post-construction pavement subsidence condition is obtained, and the difference between the post-construction pavement subsidence and the target subsidence which are simulated and predicted is compared; the method comprises the following steps: randomly changing or purposefully changing the position, the size and the degradation degree of a degradation region according to a rule, carrying out repeated trial calculation to finally obtain a foundation degradation position, the size and the degradation degree which are almost consistent with target subsidence, and establishing a degradation region determined by a plurality of groups of degradation region parameters in a finite element or discrete element model, and respectively carrying out combined calculation with other loads of the road surface load calculation working condition, respectively calculating roadbed structure load effects corresponding to each degradation area, and designing or evaluating roadbed strength, deformation and stability by taking the most unfavorable value or average value.

Description

Technical Field

[0001] The invention relates to the technical field of frozen soil roadbed structure calculation, and in particular to a roadbed analysis and calculation method taking into account local degradation of permafrost roadbed. Background Art

[0002] When building roads in frozen areas, the freeze-thaw cycle of the roadbed must be considered. During the freezing and thawing process of the foundation, water migration will form ice lenses under the roadbed. The melting of the ice lenses will cause the local soil properties to deteriorate greatly, resulting in a reduction in the local bearing capacity of the roadbed, which will lead to uneven settlement of the roadbed in frozen areas.

[0003] At present, the design scheme of roadbed structure mainly considers the overall thawing and settlement characteristics, and the local soil deterioration mainly relies on the comprehensive consideration of the designer's experience. When calculating the foundation, it is necessary to consider the load combination of soil deterioration. Due to the nonlinearity of soil materials, there is a nonlinear relationship between load effects and load variables. Load combination must be performed first, and then the load effect is directly obtained. However, since the scope and degree of soil deterioration after freeze-thaw cycles are difficult to predict, the foundation verification in the design stage only roughly estimates the impact of local soil deterioration on the roadbed based on the overall thawing and settlement characteristics of the foundation soil, or assumes that the soil is a multi-layer homogeneous material. At present, there is still a lack of roadbed design methods that consider the degradation of local soil after freeze-thaw cycles.

[0004] The patent number is CN202210247719.X, and the patent name is "A method for comparing pavement base plans in seasonally frozen soil areas". It discloses a method for comparing pavement base plans in seasonally frozen soil areas, which takes into account the impact of frost heave and thaw settlement in frozen soil areas on the benefit indicators and cost indicators of the pavement base. However, it only provides a pavement design method, but does not provide a roadbed design method. It does not consider the superposition method of the effects of multiple nonlinear influencing factors on the bearing capacity, deformation, and stability of the foundation, and does not consider the impact of the deterioration of the underlying foundation frozen soil on the roadbed deformation.

[0005] The patent number is CN202310767954.4, and the patent name is a patent for a method for evaluating the degree of freeze-thaw damage of frozen soil roadbed based on sequential deviation. It is based on the ice-containing sequential deviation and takes into account the influence of external temperature changes to obtain the roadbed freeze-thaw damage field, revealing the spatial distribution of roadbed freeze-thaw damage. It can simulate and calculate the surface damage of the roadbed, but it cannot calculate the deep local degradation of the roadbed that is prone to local subsidence. Summary of the invention

[0006] In view of this, in order to solve the above problems, the present invention provides a roadbed analysis and calculation method taking into account the local degradation of permafrost roadbed.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: a roadbed analysis and calculation method considering local degradation of permafrost roadbed, the steps are:

[0008] S1: Determine the size of the road subsidence area, determine the diameter D and height H of the subsidence area according to the target guidance, and obtain the target subsidence;

[0009] S2: Assuming the location, size, and degree of deterioration of the deteriorated area, a calculation model is established, and numerical analysis is performed through finite element or discrete element to obtain the post-construction pavement settlement situation;

[0010] S3: Compare the post-construction road surface settlement predicted by simulation with the target settlement, randomly change or change the location, size and degree of deterioration of the deterioration area purposefully according to the rules, and finally obtain multiple sets of foundation deterioration locations, sizes and degrees of deterioration that almost match the target settlement and meet the conditions through repeated trial calculations;

[0011] S4: Assume that the foundation deterioration meets the above-mentioned location, size, and degree of deterioration, simulate the construction process, combine the given roadbed scheme, consider the load combination such as vehicle load, and verify the stress and deformation of the roadbed structure under the nonlinear load combination of multiple working conditions. When three groups of deterioration solutions are taken, take the most unfavorable value as the reference value; when the value is greater than three groups, take the average value as the reference value for design or evaluation.

[0012] Further, the specific method of step S2 is: the deteriorated area is located directly below or below the subsidence area, and multiple groups of deteriorated area parameters are assumed to include the diameter d i , Degraded area height b i 、Deteriorated area distance to road surface h i , the distance from the center of the deteriorated area to the center of the subsidence is L i , establish a finite element or discrete element model, set the elastic modulus, internal friction angle, and cohesion parameters of the soil in the local deterioration area to the minimum value to simulate the rapid deterioration of the soil caused by water migration, and calculate the settlement range parameter D i , H i .

[0013] Further, the specific method of step S3 is: according to the principle of being favorable or unfavorable to the subsidence area, the position, size, and degree of degradation of the degradation area are randomly changed or regularly and purposefully changed, and the maximum and minimum values ​​of each parameter are calculated to obtain the feasible domain of the degradation area parameters, and the initial parameters are repeatedly modified for trial calculation, and the subsidence area parameters D calculated by comparing the assumed degradation area are obtained. i , H i and target subsidence area parameters D, H, and screen 3 or more groups of assumed subsidence area parameters di, bi, hi, Li (i∈(3,n)) that meet the error range.

[0014] Furthermore, the diameter D and height H of the subsidence area in step S1) are determined by statistics based on the road damage conditions in the frozen soil area.

[0015] Compared with the prior art, the advantages of the present invention are as follows:

[0016] 1. The present invention determines the scope of settlement through target orientation as the basis, calculates settlement by randomly selecting or purposefully modifying local degradation parameters of foundation, and iterates the calculation to make the calculated settlement closer to the target settlement, thereby determining the local degradation parameters of foundation. A method for calculating local degradation of roadbed is proposed, which is more objective than the traditional experience-based evaluation and design method.

[0017] 2. The present invention provides a foundation verification method that takes into account local foundation deterioration. The verification process can consider the nonlinear superposition of local soil deterioration and other loads acting on the foundation soil, and can more comprehensively evaluate the foundation bearing capacity, deformation and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of roadbed deterioration according to the present invention.

[0019] Figure 2 Schematic diagram of the flow chart of the calculation method for roadbed analysis considering local degradation. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The technical solutions provided by the embodiments of the present invention are described in detail below in conjunction with the drawings.

[0021] The present invention provides a roadbed analysis and calculation method considering local degradation of permafrost roadbed, the steps are:

[0022] S1: Determine the size of the road subsidence area, determine the diameter D and height H of the subsidence area according to the target orientation, and obtain the target subsidence; the diameter D and height H of the subsidence area are determined by statistics based on the road disease conditions in the frozen soil area;

[0023] S2: Assuming the location, size, and degree of deterioration of the deterioration area, a calculation model is established, and numerical analysis is performed through finite element or discrete element to obtain the post-construction road surface settlement. The deterioration area is located directly below or below the side of the settlement area, and multiple groups of deterioration area parameters are assumed, including the diameter d i , Degraded area height b i 、Deteriorated area distance to road surface h i , the distance from the center of the deteriorated area to the center of the subsidence is L i, establish a finite element or discrete element model, set the elastic modulus, internal friction angle, and cohesion parameters of the soil in the local deterioration area to the minimum value to simulate the rapid deterioration of the soil caused by water migration, and calculate the settlement range parameter D i , H i ;

[0024] S3: Compare the post-construction road surface settlement predicted by simulation with the target settlement, randomly change or change the location, size and degree of deterioration of the deterioration area purposefully according to the rules, and finally obtain multiple sets of foundation deterioration locations, sizes and degrees of deterioration that almost match the target settlement and meet the conditions through repeated trial calculations;

[0025] According to the principle of advantages and disadvantages for the subsidence area, the position, size and degree of deterioration of the deterioration area are randomly changed or regularly and purposefully changed to calculate the maximum and minimum values ​​of each parameter, and the feasible domain of the deterioration area parameters is obtained. The initial parameters are repeatedly modified for trial calculation, and the subsidence area parameters D calculated by comparing the assumed deterioration area are obtained. i , H i and target subsidence area parameters D, H, and screen 3 or more groups of assumed subsidence area parameters di, bi, hi, Li (i∈(3,n)) that meet the error range;

[0026] S4: Assume that the foundation deterioration meets the above-mentioned location, size, and degree of deterioration, simulate the construction process, combine the given roadbed scheme, consider the load combination such as vehicle load, and verify the stress and deformation of the roadbed structure under the nonlinear load combination of multiple working conditions. When three groups of deterioration solutions are taken, take the most unfavorable value as the reference value; when the value is greater than three groups, take the average value as the reference value for design or evaluation.

[0027] Embodiment 1:

[0028] A roadbed analysis and calculation method considering local degradation of permafrost roadbed, assuming that the deteriorated area is located directly below the subsidence area, uses a random change method to determine the deteriorated area parameters. The flow chart is as follows Figure 2 As shown:

[0029] S1: Determine the size of the road subsidence area, determine the diameter D and H of the subsidence area according to the target orientation, and obtain the target subsidence; among them, D and H can be determined by statistics based on the road disease conditions in the frozen soil area, such as Figure 1 As shown;

[0030] S2: Assuming that the deteriorated area is located directly below the subsidence area, multiple sets of assumed deteriorated area parameters are used, including the diameter d i , Degraded area height b i 、Deteriorated area distance to road surface h i, establish a calculation model, set the elastic modulus, internal friction angle and cohesion parameters of the soil in the local degradation area to the minimum value, and calculate the settlement range parameter D i , H i ;

[0031] S3: Compare the post-construction road settlement predicted by simulation with the target settlement. The selection of random parameters in the deterioration area can be based on the principle of advantages and disadvantages for the settlement area, and the maximum and minimum values ​​of each parameter can be calculated to obtain the feasible domain of the deterioration area parameters. In the feasible domain, two of the three deterioration area parameters can be randomly selected, and the other parameter can be calculated iteratively to gradually approach the target settlement. For example, the selected parameter d i and b i , in the feasible region of the degradation area, h i The maximum value is h0, the minimum value is h1, and the corresponding subsidence range parameters are D0, H0, D1, H1. If the errors of D0, H0 and D1, H1 cannot meet the requirements, then Use finite element method or discrete element method to get D j , H j , if D j , H j If the error does not meet the requirement, Iterate the calculation until the subsidence area parameters meet the requirements; repeatedly modify the initial parameters for trial calculation, and compare the subsidence area parameters D calculated by the assumed deterioration area i , H i and target subsidence area parameters D, H, and screen 3 or more groups of assumed subsidence area parameters di, bi, hi, Li (i∈(3,n)) that meet the error range.

[0032] S4: Assume that the foundation deterioration meets the above-mentioned location, size, and degree of deterioration, simulate the construction process, combine the given roadbed scheme, consider the load combination such as vehicle load, and verify the stress and deformation of the roadbed structure under the nonlinear load combination of multiple working conditions. When three groups of deterioration solutions are taken, take the most unfavorable value as the reference value; when the value is greater than three groups, take the average value as the reference value for design or evaluation.

[0033] Embodiment 2:

[0034] A roadbed analysis and calculation method considering local deterioration of permafrost roadbed, assuming that the deteriorated area is located on the side of the subsidence area, uses a purposeful adjustment method to determine the deteriorated area parameters. The flow chart is as follows Figure 2 As shown:

[0035] S1: Determine the size of the road subsidence area, determine the diameter D and H of the subsidence area according to the target orientation, and obtain the target subsidence; among them, D and H can be determined by statistics based on the road disease conditions in the frozen soil area, such as Figure 1 As shown;

[0036] S2: Assuming that the deteriorated area is located on the side of the subsidence area, multiple groups of deteriorated area parameters are assumed, including the diameter d i , Degraded area height b i 、Deteriorated area distance to road surface h i , the distance from the center of the deteriorated area to the center of the subsidence is L i , establish a finite element or discrete element model, set the elastic modulus, internal friction angle, and cohesion parameters of the soil within the local degradation area to the minimum value, and calculate the settlement range parameter D i , H i ;

[0037] S3: Through trial calculation, d i 、b i 、h i , L i With D i , H i The relationship between the deterioration area and the target area is analyzed by multivariate logistic regression analysis. The deterioration area parameters that contribute more to the subsidence range in the regression analysis are adjusted first, and the subsidence range is calculated until the subsidence area is close to the target subsidence. The initial parameters with smaller contributions are repeatedly modified for trial calculation. The subsidence area parameters D calculated by comparing the assumed deterioration area are calculated. i , H i and the target subsidence area parameters D and H, 3 or more sets of assumed subsidence area parameters di, bi, hi, Li (i∈(3,n)) that meet the error range can be obtained.

[0038] S4: Assume that the foundation deterioration meets the above-mentioned location, size, and degree of deterioration, simulate the construction process, combine the given roadbed scheme, consider the load combination such as vehicle load, and verify the stress and deformation of the roadbed structure under the nonlinear load combination of multiple working conditions. When three groups of deterioration solutions are taken, take the most unfavorable value as the reference value; when the value is greater than three groups, take the average value as the reference value for design or evaluation.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A roadbed analysis and calculation method considering local degradation of permafrost roadbed, characterized in that: The steps are: S1: Determine the size of the road subsidence area, determine the diameter D and height H of the subsidence area according to the target guidance, and obtain the target subsidence; S2: Assuming the location, size, and degree of deterioration of the deteriorated area, a calculation model is established, and numerical analysis is performed through finite element or discrete element to obtain the post-construction pavement settlement situation; S3: Compare the post-construction road surface settlement predicted by simulation with the target settlement, randomly change or change the location, size and degree of deterioration of the deterioration area purposefully according to the rules, and finally obtain multiple sets of foundation deterioration locations, sizes and degrees of deterioration that almost match the target settlement and meet the conditions through repeated trial calculations; S4: Assume that the foundation deterioration meets the above-mentioned location, size, and degree of deterioration, simulate the construction process, combine the given roadbed scheme, consider the load combination such as vehicle load, and verify the stress and deformation of the roadbed structure under the nonlinear load combination of multiple working conditions. When three groups of deterioration solutions are taken, take the most unfavorable value as the reference value; when the value is greater than three groups, take the average value as the reference value for design or evaluation.

2. A roadbed analysis and calculation method considering local degradation of permafrost roadbed according to claim 1, characterized in that: The specific method of step S2 is: the deteriorated area is located directly below or below the subsidence area, and multiple groups of deteriorated area parameters are assumed to include the diameter d i , Degraded area height b i 、Deteriorated area distance to road surface h i , the distance from the center of the deteriorated area to the center of the subsidence is L i , establish a finite element or discrete element model, set the elastic modulus, internal friction angle, and cohesion parameters of the soil in the local deterioration area to the minimum value to simulate the rapid deterioration of the soil caused by water migration, and calculate the settlement range parameter D i , H i .

3. A roadbed analysis and calculation method considering local degradation of permafrost roadbed according to claim 1 or 2, characterized in that: The specific method of step S3 is: according to the principle of being favorable or unfavorable to the subsidence area, the position, size, and degree of degradation of the degradation area are randomly changed or regularly and purposefully changed, and the maximum and minimum values ​​of each parameter are calculated to obtain the feasible domain of the degradation area parameters, and the initial parameters are repeatedly modified for trial calculation. By comparing the calculated subsidence area parameters D of the assumed degradation area, the subsidence area parameters D i , H i and target subsidence area parameters D, H, and screen 3 or more groups of assumed subsidence area parameters di, bi, hi, Li (i∈(3,n)) that meet the error range.

4. A roadbed analysis and calculation method considering local degradation of permafrost roadbed according to claim 3, characterized in that: The diameter D and height H of the subsidence area in step S1) are determined by statistics based on the road damage conditions in the frozen soil area.

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