A method for comparing and selecting road base solutions in seasonally frozen soil areas

Abstract

The invention discloses a method for comparing and selecting road base programs in seasonal frozen soil areas, comprising the following steps: step 1: analyzing the special geographical environment of seasonal frozen soil areas, clarifying the evaluation object system of the program, and listing the influencing factors of the research object; step 2: analyzing the manifestation of the influencing factors at all levels, describing the influence mechanism of the manifestation of the influencing factors on the research object, determining the evaluation index system, and constructing a pre-analysis framework for comprehensive evaluation; step 3: based on a data evaluation model, unifying the original observation point data of the evaluation index, obtaining a forward matrix and performing normalization processing to eliminate the influence of the dimensions of the indicators at all levels, and determining the analysis data matrix; step 4: calculating the distance between each evaluation object and the optimal program and the worst program, and using this as the basis for evaluating the pros and cons; step 5: sorting the distance between the evaluation object and the optimal solution and the worst solution, judging the relative closeness of each evaluation object to the optimal program, and realizing the optimal comparison and selection of the program.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering, and in particular relates to a method for comparing and selecting road base solutions in seasonally frozen soil areas. Background Art

[0002] China has a vast territory and a large difference in latitude between north and south, resulting in the distribution of permafrost areas accounting for nearly 3 / 4 of the country's land area, of which seasonal permafrost areas account for 1 / 2 of the permafrost areas. Due to the natural alternation of frost heave in winter and thaw in spring in seasonal permafrost areas, road projects have put forward special requirements for the low-temperature crack resistance, frost resistance, and deformation resistance of the pavement, especially the pavement base. Therefore, the selection of the pavement base structure plan in seasonal permafrost areas has become one of the most important decision-making challenges.

[0003] At present, for the construction of pavement base in permafrost areas, road designers mostly choose semi-rigid base stabilized by inorganic binders. The reason is mainly due to the high strength, good integrity, excellent flatness and road performance of the semi-rigid base, but the difficulties of construction and pouring, large shrinkage deformation and road cracks caused by it are ignored. In a few permafrost areas, the design of the pavement base structure is mainly based on the designer's construction experience. The design of the pavement base structure based on personal preference lacks standardization, rationality and universality, and it is easy for the designer to make wrong decisions, resulting in irreversible damage to the entire pavement project.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] In order to ensure that the road base in seasonally frozen areas has sufficient bearing strength, freezing stability and low-temperature deformation resistance, the present invention provides a method for comparing and selecting road base structure schemes in seasonally frozen areas that is reliable, scientific and feasible.

[0006] In order to achieve the above object, the present invention provides a method for comparing and selecting road base solutions in seasonally frozen soil areas, comprising the following steps:

[0007] Step 1: Analyze the special geographical environment of seasonal frozen soil areas, clarify the evaluation object system of pavement base structure scheme in frozen soil areas, and list the influencing factors of the comprehensive characteristics of the research object;

[0008] Step 2: Analyze the manifestation of influencing factors at all levels of the pavement base structure scheme in seasonal frozen soil areas, describe the impact mechanism of the manifestation of influencing factors on the research object, determine the evaluation index system, and build a pre-analysis framework for comprehensive evaluation;

[0009] Step 3: Based on the data evaluation model, unify the original observation point data of the evaluation index (forward processing), obtain the forward matrix, and then normalize the forward matrix to eliminate the influence of the dimensions of indicators at all levels, and determine the analysis data matrix;

[0010] Step 4: By judging the evaluation indicators at all levels in the analysis data matrix, determine the optimal and worst values ​​of each indicator, and then calculate the distance between each evaluation object and the optimal and worst solutions respectively, which serves as the basis for evaluation;

[0011] Step 5: Sort the distances between the evaluation objects and the optimal solution and the worst solution, determine the relative closeness of each evaluation object to the optimal solution, and achieve optimal comparison and selection of pavement base structure solutions in seasonally frozen soil areas.

[0012] Preferably, in step 1, the characteristics of high temperature difference, long sunshine, and frozen soil in seasonal frozen areas are comprehensively considered, and three pavement base structure schemes of rigid, semi-rigid, and flexible are selected as evaluation objects, and the influencing factors of the all-round characteristics of the research object are determined according to the special geographical environment;

[0013] Preferably, in step 2, based on the positive and negative impact mechanisms of the influencing factors at all levels, the extremely large indicators and extremely small indicators in the research object are judged, the extremely large indicators are benefit indicators, and the extremely small indicators are cost indicators, the mediating effects and regulatory effects between the evaluation indicators at all levels are explored, and a pre-analysis framework for comprehensive evaluation is constructed;

[0014] Preferably, in step 3, all indicators are transformed into extremely large indicators, a positive correlation between the evaluation object and each evaluation indicator is established in the comprehensive evaluation process, and then the vector data normalization formula is used. Among them, x ij : The influence of the i-th teaching evaluation indicator on the j-th evaluation object, eliminating the influence of the dimensions of indicators at all levels, and determining the analysis data matrix;

[0015] Preferably, in step 4, the contribution of a single evaluation index to all evaluation objects is determined, and the maximum value of each evaluation index is selected to form a column vector as the optimal value of each index: + ={max(z 11 ,z 21 ,…z n1 ),max(z 12 ,z 22 ,…z n2 ),…,max(z 1n ,z 2n ,…z nn )}, similarly select the minimum value of each evaluation index to form a column vector as the worst value of each index: z- ={min(z 11 ,z 21 ,…z n1 ),min(z 12 ,z 22 ,…z n2 ),…,min(z 1n ,z 2n ,…z nn )}; Calculate the optimal value Z of each element of each evaluation index + The distance D + , and the worst value Z - The distance D - ;

[0016] Preferably, in step 5, the relative closeness of each evaluation object to the optimal solution is judged by the effect degree of each evaluation index on the evaluation object, and the multi-objective decision analysis of the pavement base solution in the frozen soil area is determined to achieve the optimal comparison of the pavement base structure solution in the seasonal frozen soil area.

[0017] The method for comparing and selecting road base solutions in seasonally frozen soil areas provided by the present invention has the following beneficial effects:

[0018] The present invention effectively solves the problems of difficulty in pouring the construction of pavement base in seasonally frozen soil areas, large shrinkage and deformation resulting in pavement cracks and other diseases, and overcomes a series of engineering problems such as construction and maintenance caused by excessive reliance on the designer's construction experience in the design of pavement base structure schemes. The present invention provides a reliable, scientific and feasible method for comparing pavement base structure schemes in seasonally frozen soil areas, which can maximize the full life cycle of roads in seasonally frozen soil areas while more standardized and reasonable pavement base design. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention provides a pre-analysis framework for comprehensive evaluation of a road base program comparison method in seasonally frozen soil areas. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with specific embodiments and drawings to help understand the content of the present invention.

[0021] The present invention provides a method for comparing and selecting road base solutions in seasonally frozen areas, comprising the following steps:

[0022] Step 1: The high-altitude frozen soil area has a special environment, with complex and multi-purpose terrain and landforms, and has the characteristics of high temperature difference, long sunshine, and many frozen soils. Due to the natural alternation of frost heave in winter and thaw in spring in seasonal frozen soil areas, road projects have put forward special requirements for the low-temperature crack resistance, frost resistance, and deformation resistance of the pavement, especially the pavement base. So far, a system of evaluation objects for three pavement base schemes, namely rigid, semi-rigid and flexible base, has been established. Considering the benefit factors and cost factors in the entire life cycle of the pavement base, bearing strength, freezing stability, fatigue resistance, and deformation resistance are selected as benefit indicators, and construction cost, energy consumption, and maintenance cost are selected as cost indicators;

[0023] Step 2: Take the benefit indicators (bearing strength, freezing stability, fatigue resistance and deformation resistance) as the large-scale indicators, and the cost indicators (construction cost, energy consumption and maintenance cost) as the small-scale indicators. There is a positive mediating effect between the indicators at all levels in the benefit factor (for example, changes in energy consumption will inevitably have a positive impact on the construction cost), while there is more mutual regulation effect between the indicators at all levels in the cost factor. Based on the mediating effect and regulation effect between the evaluation indicators at all levels, a pre-analysis framework for comprehensive evaluation is constructed;

[0024] Step 3: Based on the measured data values ​​of the evaluation indicators at all levels, all indicators are positively transformed into maximum value indicators. The formula for converting extremely small indicators into extremely large indicators is shown in Formula 1. The influence of the dimensions of indicators at all levels is eliminated through the vector data normalization formula (see Formula 2), and the analysis data matrix is ​​established;

[0025] max(x i1 ,x i2 ,…,x in )-x ij (1)

[0026]

[0027] Among them, x ij : The influence of the i-th teaching evaluation indicator on the j-th evaluation object.

[0028] Step 4: Determine the contribution of a single evaluation index to all evaluation objects, select the maximum value of each evaluation index, and form a column vector as the optimal value of each index (see formula 3). Similarly, select the minimum value of each evaluation index and form a column vector as the worst value of each index (see formula 4). And calculate the relationship between each element of each evaluation index and the optimal value Z according to formulas 5 and 6 + The distance D + , and the worst value Z - The distance D - ;

[0029] z + ={max(z11 ,z 21 ,…z m1 ),max(z 12 ,z 22 ,…z m2 ),…,max(z 1n ,z 2n ,…z mn )} (3)

[0030] z - ={min(z 11 ,z 21 ,…z m1 ),min(z 12 ,z 22 ,…z m2 ),…,min(z 1n ,z 2n ,…z mn )} (4)

[0031]

[0032]

[0033] Among them, z ij : Corresponding elements in the analysis data matrix. D i + : The distance between the i-th evaluation object and the optimal value. D i - : The distance between the ith evaluation object and the worst value.

[0034] Step 5: By using the effect index and cost index to determine the influence of the three types of pavement base, the relative closeness between the three types of pavement base structure schemes in seasonal frozen soil areas and the optimal scheme is determined (see Formula 7). The relative closeness is ranked and the multi-objective decision analysis of the pavement base scheme in frozen soil areas is determined to achieve the optimal comparison of the pavement base structure scheme in seasonal frozen soil areas.

[0035]

[0036] Among them, C i : The relative closeness between the i-th evaluation index and the optimal value.

[0037] A highway in Qinghai Province was selected as the research object, and rigid, semi-rigid and flexible bases were selected as test sections, with a unified section length of 2 km. For benefit indicators, the rigid base test section is mainly based on ordinary concrete, which has the characteristics of high strength, high durability, and high plate body; the semi-rigid base test section is mainly based on cement stabilized aggregate, which has the characteristics of greater strength and higher integrity; the flexible base test section is mainly based on graded crushed stone, which is not easy to produce thermal shrinkage and shrinkage cracks, and has good freezing stability, but cannot withstand high strength. Therefore, by comparing the benefit indicators of the three types of pavement base measured sections, "1, 3, 5" are judged according to the relative degree of excellence. At the same time, the construction cost data of the test sections of three different pavement base structure schemes are queried, and the final measured data of the impact effects of various indicators on the three pavement base schemes are shown in Table 1.

[0038] Table 1 Measured sample data of indicators at all levels for different pavement base solutions

[0039]

[0040] Step 1: Due to the natural alternation of frost heave in winter and thaw settlement in spring in seasonal frozen soil areas, road projects have put forward special requirements for the low-temperature crack resistance, frost resistance, and deformation resistance of the pavement, especially the pavement base. So far, a system of evaluation objects for three pavement base schemes, namely rigid, semi-rigid, and flexible bases, has been established. Considering the benefit and cost factors of the pavement base throughout its life cycle, bearing strength, freezing stability, fatigue resistance, and deformation resistance are selected as benefit indicators, and construction cost, energy consumption, and maintenance cost are selected as cost indicators;

[0041] Step 2: Take the benefit index as the largest index and the cost index as the smallest index. There is a positive mediation effect between the indicators at all levels in the benefit factor (for example, changes in energy consumption will inevitably have a positive impact on construction costs), while there is more mutual regulation effect between the indicators at all levels in the cost factor. Based on the mediation effect and regulation effect between the evaluation indicators at all levels, the pre-analysis framework for comprehensive evaluation is constructed. Figure 1 ;

[0042] Step 3: Based on the measured data values ​​of the evaluation indicators at all levels, the extremely small indicators are converted into extremely large indicators through formula (1) in the technical solution; at the same time, the vector data is normalized through formula (2) in the technical solution to eliminate the influence of the dimensions of the indicators at all levels, and the analysis data matrix is ​​established as follows;

[0043] Optionally, step 3 includes:

[0044] 3.1 Convert all indicators into very large indicators, that is, make the indicators positive, see Table 2 below

[0045] Table 2 Positive data of various indicators on measured samples of different pavement base solutions

[0046]

[0047]

[0048] 3.2 Normalize the original data to eliminate the dimension and obtain the analysis data matrix:

[0049]

[0050] Step 4: Determine the contribution of a single evaluation index to all evaluation objects. Select the maximum value of each evaluation index through formula (3) in the technical solution to form a column vector as the optimal value of each index. Similarly, select the minimum value of each evaluation index to form a column vector as the worst value of each index. And calculate the relationship between each element of each evaluation index and the optimal value z according to formulas (5) and (6) in the technical solution. + The distance D + , and the worst value z - The distance D - ;

[0051] Optionally, step 4 includes:

[0052] 4.1 Find the optimal and worst values ​​of each indicator and establish the optimal value vector z + and the worst value vector z - :

[0053]

[0054]

[0055] 4.2 Calculate the distances between the three pavement base structure schemes and the optimal and worst values ​​as shown in Table 3:

[0056] Table 3 Distance between the pavement base structure scheme and the optimal and worst values

[0057]

[0058] Step 5: The relative closeness between the three structural schemes of the pavement base in seasonal frozen soil areas and the optimal scheme is determined by formula (7) in the technical scheme (see Table 4), and the relative closeness is ranked to determine the multi-objective decision analysis of the pavement base scheme in frozen soil areas, so as to achieve the optimal comparison of the pavement base structure scheme in seasonal frozen soil areas.

[0059] Table 4 The relative closeness between the three structural schemes of the pavement base and the optimal scheme

[0060]

[0061] For a highway in Qinghai Province located in a seasonal frozen land area, the special geographical environment of the seasonal frozen land area was considered, and the benefit index and cost index measured data evaluation model were used for analysis. The results showed that compared with the rigid and semi-rigid base solutions, the relative closeness of the flexible base to the optimal solution was 0.599 at most. Therefore, for this test section in Qinghai Province in a seasonal frozen land area, under the premise of fully considering the relevant influencing factors, the flexible base is the optimal structural solution for the pavement base of this section of highway.

[0062] The invention concept is described in detail using specific examples herein, and the description of the above embodiments is only used to help understand the core idea of ​​the invention. It should be pointed out that any obvious modification, equivalent substitution or other improvement made by a person of ordinary skill in the art without departing from the invention concept should be included in the protection scope of the present invention.

Claims

1. A method for comparing and selecting road base solutions in seasonally frozen areas, characterized in that: The following steps are involved: Step 1: Analyze the special geographical environment of seasonal frozen soil areas, clarify the evaluation object system of pavement base structure schemes in frozen soil areas, and list the influencing factors of the all-round characteristics of the research object; the environment of high-altitude frozen soil areas is special, the terrain is complex and multi-purpose, and it has the characteristics of high temperature difference, long sunshine, and many frozen soils. Due to the natural alternation of frost heave in winter and thaw in spring in seasonal frozen soil areas, road projects put forward special requirements on the low-temperature crack resistance, frost resistance, and deformation resistance of the pavement, especially the pavement base. So far, an evaluation object system of three pavement base schemes, rigid, semi-rigid and flexible base, is established. Considering the benefit factors and cost factors in the whole life cycle of the pavement base, bearing strength, freezing stability, fatigue resistance, and deformation resistance are selected as benefit indicators. Select construction cost, energy consumption and maintenance cost as cost indicators; Step 2: Analyze the manifestation of influencing factors at all levels of the road base structure scheme in seasonal frozen soil areas, characterize the influence mechanism of the manifestation of influencing factors on the research object, determine the evaluation index system, and construct a pre-analysis framework for comprehensive evaluation; take the benefit indicators including bearing strength, freezing stability, fatigue resistance and deformation resistance as the extremely large indicators, and take the cost indicators including construction cost, energy consumption and maintenance cost as the extremely small indicators. There is a positive mediating effect between the indicators at all levels in the benefit factors, and there is more mutual regulation effect between the indicators at all levels in the cost factors. Based on the mediating effect and regulation effect between the evaluation indicators at all levels, a pre-analysis framework for comprehensive evaluation is constructed; Step 3: Based on the data evaluation model, unify the original observation point data of the evaluation index to obtain the forward matrix, and then normalize the forward matrix to eliminate the influence of the dimensions of the indicators at all levels to determine the analysis data matrix; Step 4: By judging the evaluation indicators at all levels in the analysis data matrix, determine the optimal and worst values ​​of each indicator, and then calculate the distance between each evaluation object and the optimal and worst solutions respectively, which is used as the basis for evaluation; judge the contribution of a single evaluation indicator to all evaluation objects, select the maximum value of each evaluation indicator, and form a column vector as the optimal value of each indicator: z + ={max(z 11 ,z 21 ,…z n1 ),max(z 12 ,z 22 ,…z n2 ),…,max(z 1n ,z 2n ,…z nn )}, similarly select the minimum value of each evaluation index to form a column vector as the worst value of each index: z - ={min(z 11 ,z 21 ,…z n1 ),min(z 12 ,z 22 ,…z n2 ),…,min(z 1n ,z 2n ,…z nn )}; Calculate the optimal value Z of each element of each evaluation index + The distance D + , and the worst value Z - The distance D - ; Step 5: Sort the distances between the evaluation objects and the optimal solution and the worst solution, determine the relative closeness of each evaluation object to the optimal solution, and achieve optimal comparison and selection of pavement base structure solutions in seasonally frozen soil areas.

2. The method for selecting a road base plan in a seasonally frozen soil region according to claim 1, characterized in that: In step 1, the high temperature difference, long sunshine and frozen soil characteristics of seasonal frozen soil areas are comprehensively considered, and three pavement base structure schemes of rigid, semi-rigid and flexible are selected as evaluation objects, and the influencing factors of the all-round characteristics of the research object are determined according to the special geographical environment.

3. The method for selecting a road base solution in a seasonally frozen soil region according to claim 1, characterized in that: In step 2, based on the positive and negative impact mechanisms of influencing factors at all levels, the extremely large indicators and extremely small indicators in the research object are judged, the extremely large indicators are benefit indicators, and the extremely small indicators are cost indicators, the mediating effects and regulatory effects between the evaluation indicators at all levels are explored, and a pre-analysis framework for comprehensive evaluation is constructed.

4. The method for selecting a road base plan in a seasonally frozen soil region according to claim 1, characterized in that: In step 3, all indicators are transformed into extremely large indicators, and a positive correlation between the evaluation object and each evaluation indicator is established in the comprehensive evaluation process, and then the vector data normalization formula is used. Among them, x ij :The influence of the i-th teaching evaluation indicator on the j-th evaluation object, eliminate the influence of the dimensions of indicators at all levels, and determine the analysis data matrix.

5. The method for selecting a road base solution in a seasonally frozen soil region according to claim 1, characterized in that: In step 5, the relative closeness of each evaluation object to the optimal solution is judged by the effect of each evaluation index on the evaluation object, and the multi-objective decision analysis of the pavement base solution in the frozen soil area is determined to achieve the optimal comparison of the pavement base structure solution in the seasonal frozen soil area.

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