CN110765691B - Four-layer pavement modulus back calculation method based on FWD deflection basin geometric features - Google Patents
Four-layer pavement modulus back calculation method based on FWD deflection basin geometric features Download PDFInfo
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Abstract
The invention discloses a four-layer pavement modulus back calculation method based on geometrical characteristics of an FWD deflection basin, which comprises the following steps: 1. calculating a theoretical deflection basin and a corresponding characteristic value of the pavement to be back calculated by adopting an elastic layered system mechanical model; 2. establishing a relation model of equivalent distal deflection points and soil base modulus by adopting a nonlinear function; 3. establishing a relation model of the center point deflection ratio and the surface layer and base layer modulus ratio by adopting a nonlinear function; 4. establishing a relation model of the deflection ratio of the fourth point and the central point and the modulus ratio of the surface layer and the subbase layer by adopting a nonlinear function; 5. and extracting geometrical characteristic values of the actually measured deflection basin according to the constructed relation model, and respectively reversely calculating modulus parameters of each structural layer corresponding to the actually measured FWD deflection basin according to two different convergence discrimination modes of the deflection of the central point and the area of the deflection basin. The four-layer modulus back calculation result is stable, has small difference from a theoretical calculation value, and can provide a reliable basis for evaluating the actual modulus state of each structural layer of the in-service pavement.
Description
Technical Field
The invention relates to a four-layer modulus back calculation method based on geometrical characteristics of an FWD deflection basin, and belongs to the technical field of road engineering.
Background
The FWD (Falling Weight Deflectometer, drop hammer type deflectometer) is used as one of the most advanced pavement nondestructive testing equipment in the world at present, and the pavement surface deflectometer detected by the FWD is used for obtaining the modulus parameters of different structural layers by a modulus back calculation method, so that the method is a method for effectively evaluating the service state of each structural layer of the in-service pavement.
The existing modulus back calculation method mainly comprises an iteration method and a database search method, is widely applied to pavement engineering, and has certain limitations. If the difference between the actual measurement deflection basin and the theoretical deflection basin is large, the situation that the actual measurement deflection basin has no solution is calculated in a back calculation way; the geometrical characteristics of the deflection basin are less considered, so that the back calculation result is not converged, the error is larger, and the like.
Based on the analysis of a theoretical deflection basin by using a small-deformation elastic layered mechanical system, the method provides a four-layer modulus back calculation method based on the geometrical characteristics of the FWD deflection basin and the internal relation and rules of the theoretical deflection basin in geometrical characteristics and modulus parameters of the actual measurement deflection basin, and effectively evaluates the mechanical state of the existing pavement structure.
Disclosure of Invention
The invention aims to solve the defects of the existing FWD deflection basin modulus back calculation method in China, provides the FWD deflection basin modulus back calculation method based on a mechanics-experience method, calculates a theoretical deflection basin characteristic value according to engineering experience and material characteristics, constructs a relation model of the theoretical deflection basin characteristic value and each structural layer modulus, and back calculates the modulus of each structural layer through two convergence methods of center point deflection and deflection basin area of an actually measured deflection basin.
The invention mainly comprises the following steps:
1. calculation of theoretical deflection basin and geometric characteristic value and construction of theoretical value database
In the method, considering the stability of inverse modulus calculation, the pavement structure is simplified into a four-layer system: asphalt surface layer, base layer, subbing layer and soil base, modulus and thickness are respectively marked as E 1 、h 1 ；E 2 、h 2 ；E 3 、h 3 ；E 0 The poisson ratio is selected according to conventional settings. The linear elastic layered system theory is adopted, and all the interlayer states are completely continuous.
Nine-point deflection basin D for FWD actual measurement 0 、D 1 、D 2 、D 3 、D 4 、D 5 、D 6 、D 7 、D 8 (0, 230mm,530mm, 460 mm,850mm,1160mm,1530mm,1750mm,2050 mm) from the center point in this order), and several key parameters are selected to describe the deflection basinIs characterized by the following geometry: (1) center point deflection: d (D) 0 The method comprises the steps of carrying out a first treatment on the surface of the (2) equivalent distal point deflection: (D) 6 +D 7 +D 8 ) 3, denoted 3D; (3) area of the deflection basin: s, S; (4) first point to center point deflection ratio: d (D) 1 /D 0 The method comprises the steps of carrying out a first treatment on the surface of the (5) fourth point to center point deflection ratio: d (D) 3 /D 0
And then, according to engineering experience and material characteristics, setting a wider modulus range for each layer of structure, suggesting to take 5 moduli, and then, calculating a large number of theoretical deflection basin and geometric characteristic values of the deflection basin for the combination of the moduli, so as to establish a database of the theoretical deflection basin.
2. Establishing a relation model of equivalent far-end point deflection 3D and soil base modulus
By calculating the theoretical deflection basin, the equivalent far-end deflection 3D and the soil base modulus E are summarized 0 For example, using a Bradley model fit as follows:
wherein a is 0 、b 0 Is a coefficient.
3. Establishing a central point deflection ratio D 1 /D 0 Modulus ratio E with respect to the surface layer and the base layer 1 /E 2 Is a relational model of (2)
Summarizing and summarizing theoretical deflection basin geometric feature value D 1 /D 0 And E is connected with 1 /E 2 Fitting with a high fitness function model, such as Log3P1 model, as follows:
D 1 /D 0 ＝A 1 -B 1 ·ln(E 1 /E 2 +C 1 ) Formula (2)
Wherein A is 1 、B 1 、C 1 Is a coefficient.
Secondly, establishing regression coefficients A in the fitting model 1 、B 1 、C 1 Modulus with soil E 0 Is a model of the relationship of (a). Taking the square root of the modulus of the soil base and A 1 、C 1 Coefficients respectively adopt linesSex model, and B 1 The coefficients are in a logarithmic model. The models are shown in formulas (3) - (5), and the regression coefficients are shown in Table 6.
Wherein a is 1 、b 1 、a 2 、b 2 、a 3 、b 3 Is a coefficient.
4. Establishing a fourth point-to-center point deflection ratio D 3 /D 0 Modulus ratio E with respect to topcoat and subbing layer 1 /E 3 Is a relational model of (2)
Summarizing and summarizing theoretical deflection basin geometric feature value D 1 /D 0 And E is connected with 1 /E 2 Fitting with a high fitness function model, such as Log3P1 model, as follows:
D 3 /D 0 ＝A 2 -B 2 ·ln(E 1 /E 3 +C 2 ) Formula (6)
Wherein A is 2 、B 2 、C 2 Is a coefficient.
Similar to the above analysis, a square root of the earth modulus and a regression coefficient A are established 2 、B 2 、C 2 See table 10. Wherein A is 2 、C 2 Coefficients adopt the Expdec1 model, B 2 The coefficients adopt a sliding 1 model, and the formulas (7), (8) and (9) are shown.
ExpDec1 model:
slogic 1 model:
wherein d is 1 、f 1 、g 1 、d 2 、f 2 、g 2 And alpha, k and Xc are coefficients.
5. And extracting the geometric characteristic value of the actually measured deflection basin, and respectively performing back calculation by adopting two different convergence discrimination modes of the deflection of the central point and the area of the deflection basin.
Extracting a series of geometric characteristic values for the FWD deflection basin to be measured: 3D, D 0 、S、D 1 /D 0 、D 3 /D 0 . And then, according to the relation model, reversely calculating a group of modulus parameters of different structural layers. Then according to D 0 S two different convergence modes, determining the back calculation modulus E of the final two groups of asphalt surface layer, base layer, subbase layer and soil base 1D 、E 2D 、E 3D 、E 0D And E is 1S 、E 2S 、E 3S 、E 0S 。
The invention adopts the model relation established between the geometric characteristic value and the modulus of the specific deflection basin, provides a four-layer modulus back calculation method, has small error between the calculation result and the theoretical calculation value and stable numerical value, and can provide reliable basis for evaluating the actual modulus state of each structural layer of the in-service pavement.
Drawings
FIG. 1 is a flow chart of the modulus back-calculation method of the present invention.
Detailed Description
Table 1 shows a FWD deflection basin measured for a road surface structure, and the modulus of the 4-layer structure was calculated in reverse from this.
TABLE 1 FWD actual measurement deflection basin
1. Calculation of theoretical deflection basin and extraction of geometric characteristic value
Taking a typical asphalt pavement structure as an example, a wider modulus range is set according to the material characteristics and engineering experience of each layer of the structure, such as: the modulus of the surface asphalt mixture is set to be 15000-1000 MPa, the modulus of the base cement stable graded broken stone is set to be 20000-3000 MPa, the modulus of the subbase cement soil is set to be 6000-1000 MPa, and the soil base modulus is set to be 400-100 MPa, as shown in Table 2.
Table 2: calculation parameter summary table for certain asphalt pavement structure
| Structural layer | Thickness/m | modulus/MPa | Poisson's ratio |
| Surface layer | 0.12 | E1：15000,10000,7000,4000,1000 | 0.25 |
| Basic unit (Water stable graded broken stone) | 0.4 | E2：20000,15000,10000,5000,3000 | 0.2 |
| Underlayment (Cement soil) | 0.4 | E3：6000,4500,3000,1500,1000 | 0.25 |
| Soil foundation | - | E0：400,300,250,200,150,100 | 0.35 |
According to the modulus settings, a large number of theoretical deflection basin calculations are carried out, and the relation between the geometric characteristic value of the theoretical deflection basin and the modulus (ratio) of each layer of material is analyzed one by one.
2. Establishing the relation of the soil base modulus and equivalent distal point deflection
Summarizing the differences E 1 、E 2 、E 3 And E is 0 Under the condition, the change rule of 3D deflection of the equivalent far-end point is shown in table 3.
Table 3: different E 1 、E 2 、E 3 、E 0 Distal point deflection 3D under conditions
Establishing the equivalent far-end point deflection 3D average value with the soil base modulus E according to the equivalent far-end point deflection 3D average value under different soil base moduli 0 Is a model of the relationship of (a). This example uses Bradley function fitting, with the following results:
fitting results: a, a 0 ＝-29.2076，b 0 = -0.17061, correlation coefficient R 2 ＝0.9981
3. Center point deflection ratio D 1 /D 0 Modulus ratio E with respect to the surface layer and the base layer 1 /E 2 Is a relational model of (2)
According to the calculation result of the theoretical deflection basin, summarizing and analyzing different E 1 /E 2 、E 0 Lower D 1 /D 0 See table 4.
Table 4: different E 1 /E 2 、E 0 D of (2) 1 /D 0
Fitting by adopting Log3P1 function to establish E 1 /E 2 And D 1 /D 0 The results are shown in Table 5. From the data in the table, the correlation coefficient (R 2 ) All are above 0.99, which indicates the high reliability of the fitting model.
Log3P1 model: d (D) 1 /D 0 ＝A 1 -B 1 ·ln(E 1 /E 2 +C 1 ) Formula (2)
Table 5: e (E) 1 /E 2 Value and D 1 /D 0 Value fitting model statistical parameter summary table
Secondly, establishing regression coefficients A in the fitting model 1 、B 1 、C 1 Modulus with soil E 0 Is a model of the relationship of (a). Taking the square root of the modulus of the soil base and A 1 、C 1 The coefficients are respectively linear models and B 1 The coefficients are in a logarithmic model. The models are shown in formulas (3) - (5), and the regression coefficients are shown in Table 6.
TABLE 6 coefficient A 1 、B 1 、C 1 Regression model coefficients
The introduction and calculation of equivalent stiffness of the base layer and the subbing layer. Through the analysis, E under the same combined condition of the base layer and the subbase layer is finally obtained 1 /E 2 And D 1 /D 0 Is a model of the relationship of (a).
4. Fourth Point to center Point deflection ratio D 3 /D 0 Modulus ratio E with respect to topcoat and subbing layer 1 /E 3 Is a relational model of (2)
Likewise, according to the theoretical deflection basin result calculated by the set parameters, different E are analyzed in a summarizing way 1 /E 3 、E 0 Lower D 3 /D 0 See table 7.
Table 7: different E 1 /E 3 、E 0 Lower D 3 /D 0
Still using Log3P1 model, for a set of E 2 +E 3 Build E 1 /E 3 And D 3 /D 0 The results are shown in Table 8.
D 3 /D 0 ＝A 2 -B 2 ·ln(E 1 /E 3 +C 2 ) Formula (6)
Table 8E 1 /E 3 And D 3 /D 0 Relational model
Similar to the above analysis, a square root of the earth modulus and a regression coefficient A are established 2 、B 2 、C 2 See table 9. Wherein A is 2 、C 2 Coefficients adopt the Expdec1 model, B 2 The coefficients adopt a sliding 1 model, and the formulas are shown in formulas (7), (8) and (9).
ExpDec1 model:
slogic 1 model:
TABLE 9 regression coefficient A 2 、B 2 、C 2 Relational model
5. Extraction of geometric characteristic value of actually measured deflection basin and inverse calculation of modulus
From the given deflection basin, calculate the deflection mean value of the distal point 3D, D 1 /D 0 And D 3 /D 0 Simultaneously, according to the 3D mean value of deflection of the distal point, calculating corresponding soil base modulus E according to the Bradley fitting model 0 See table 10.
TABLE 10 extraction of the geometric eigenvalues of the deflection basin
| Deflection basin | D 0 /0.1mm | S | 3D | D 1 /D 0 | D 3 /D 0 | E 0 /MPa |
| 1# | 52.4 | 65.52 | 21.7 | 0.870 | 0.682 | 354 |
Calculating E according to the established relation model 1 When D 1 /D 0 When meeting the requirements E 1 = 40947MPa, when D 3 /D 0 When meeting the requirements E 1 =31031 MPa, averaged 35989MPa, and finally determined E 1 For 36000MPa, a corresponding set of deflection basins and geometric characteristic values thereof are calculated according to engineering experience and material characteristics, and are shown in Table 11.
Table 11 determination E 1 In the case of different E 2 、E 3 Combination of two or more kinds of materialsTheoretical deflection basin of (2)
| E 1 | E 2 | E 3 | E 0 | D 0 | D 1 | D 2 | D 3 | D 4 | D 5 | D 6 | D 7 | D 8 | D 1 /D 0 | D 3 /D 0 | 3D | S |
| 36000 | 20000 | 10600 | 354 | 31.80 | 27.06 | 24.36 | 23.47 | 22.65 | 21.13 | 19.40 | 18.42 | 17.14 | 0.851 | 0.738 | 18.32 | 45.78 |
| 36000 | 16000 | 7770 | 354 | 34.49 | 29.23 | 25.94 | 24.86 | 23.88 | 22.10 | 20.12 | 19.02 | 17.59 | 0.847 | 0.721 | 18.91 | 48.30 |
| 36000 | 12000 | 5020 | 354 | 38.60 | 32.53 | 28.29 | 26.89 | 25.65 | 23.46 | 21.08 | 19.78 | 18.14 | 0.843 | 0.697 | 19.67 | 51.96 |
| 36000 | 8000 | 2550 | 354 | 45.84 | 38.47 | 32.33 | 30.30 | 28.54 | 25.54 | 22.45 | 20.82 | 18.81 | 0.839 | 0.661 | 20.69 | 58.00 |
| 36000 | 4000 | 681 | 354 | 64.40 | 53.85 | 42.49 | 38.54 | 35.23 | 29.94 | 24.97 | 22.55 | 19.75 | 0.836 | 0.598 | 22.42 | 72.27 |
The following are respectively according to the deflection D of the central point 0 And performing convergence discrimination on the two indexes of the deflection basin area S, and performing interpolation calculation to obtain a corresponding modulus back calculation result, wherein the modulus back calculation result is shown in a table 12.
Table 12 results of back-calculation modulus for each structural layer in two different convergence discriminants
And respectively calculating corresponding deflection basin according to the back calculation result, and respectively evaluating fitting accuracy of two modulus groups according to deflection root mean square error and deflection basin area error of each measuring point, wherein the result is shown in table 13.
Table 13 calculated deflection basin and error for the center point deflection and deflection basin area convergence, respectively
Claims (3)
1. A four-layer modulus back calculation method based on FWD deflection basin geometric features comprises the following steps:
1) Dividing a pavement structure to be back calculated into a surface layer, a base layer, a subbase layer and a soil base 4-layer structure according to engineering experience and material characteristics, determining the range of modulus and poisson ratio mechanical parameters of each structural layer for a pavement elastic layered system model, and calculating and constructing a theoretical value database of a pavement surface deflection basin and characteristic values thereof;
2) Establishing equivalent distal deflection point 3D and soil base modulus E by adopting high-fitting nonlinear function model 0 Is a relational model of (a);
3) Establishing a center point deflection ratio D by adopting a nonlinear function model with high fitting degree 1 /D 0 Modulus ratio E with surface layer, base layer 1 /E 0 Is a relational model of (a);
4) Establishing a fourth point deflection ratio D by adopting a nonlinear function with high fitting degree 3 /D 0 Deflection ratio E with surface layer and bottom layer 1 /E 3 Is a relational model of (a);
5) Extracting geometrical characteristic values of the actually measured deflection basin according to a relation model established by a theoretical deflection basin database and deflection D according to a central point 0 And the deflection basin area S two different convergence judging methods, determining the back calculation modulus of each structural layer of the actually measured pavement;
the theoretical value of the road surface deflection basin and the characteristic value thereof are as follows: theoretical deflection basin Di, i=0 to 8, wherein D 0 ～D 8 Respectively, the deflection at different positions of the road surface, D 0 Is the center point is bent and sink, D 8 For the most distal point to sag, the eigenvalues include: equivalent far point deflection 3 d= (D) 6 +D 7 +D 8 ) 3, center point deflection ratio D 1 /D 0 Deflection ratio D of fourth point to center point 3 /D 0 Deflection of center point D 0 And deflection basin surfaceThe modulus of the surface layer, the base layer, the subbing layer and the soil matrix are respectively represented by E 1 、E 2 、E 3 、E 0 A representation;
said step 2) equivalent distal point deflection 3D and earth base modulus E 0 Is fitted using a Bradley model as follows:
wherein a is 0 、b 0 Is a coefficient;
the center point deflection ratio D of the step 3) 1 /D 0 Modulus ratio E with surface layer, base layer 1 /E 0 Is fitted as follows using a log3P1 model:
D 1 /D 0 ＝A 1 -B 1 ·ln(E 1 /E 2 +C 1 ) Formula (2)
Wherein A is 1 、B 1 、C 1 Is a coefficient;
said step 3) A in equation (2) 1 、B 1 、C 1 Modulus with soil E 0 The relationship model of (2) is:
wherein a is 1 、b 1 、a 2 、b 2 、a 3 、b 3 Is a coefficient;
the fourth point deflection and the center point deflection ratio D in the step 4) 3 /D 0 Deflection ratio E with surface layer and bottom layer 1 /E 3 Is a model of the relationship:
D 3 /D 0 ＝A 2 -B 2 ·ln(E 1 /E 3 +C 2 ) Formula (6)
Wherein A is 2 、B 2 、C 2 Is a coefficient;
the step 4) A in the formula (6) 2 、B 2 、C 2 Modulus with soil E 0 The relationship model of (2) is:
wherein d is 1 、f 1 、g 1 、d 2 、f 2 、g 2 、α、k、x c Is a coefficient.
2. The method of claim 1, wherein in the step 1), the 4-layer structure takes 5 representative values for each layer according to engineering experience and material characteristics, and the elastic layered system analysis software is adopted to calculate the theoretical deflection basin Di of the road table.
3. The method of claim 1, wherein the high fitting degree nonlinear functions used in steps 2), 3) and 4) have correlation coefficients greater than 0.90.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102505622A (en) * | 2011-10-10 | 2012-06-20 | 同济大学 | Method for pavement condition nondestructive detection based on FWD |
| CN110110495A (en) * | 2019-06-10 | 2019-08-09 | 交通运输部公路科学研究所 | A kind of reverse calculation algorithms synchronizing determining asphalt pavement structural layer modulus and asphalt surface course Poisson's ratio |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102505622A (en) * | 2011-10-10 | 2012-06-20 | 同济大学 | Method for pavement condition nondestructive detection based on FWD |
| CN110110495A (en) * | 2019-06-10 | 2019-08-09 | 交通运输部公路科学研究所 | A kind of reverse calculation algorithms synchronizing determining asphalt pavement structural layer modulus and asphalt surface course Poisson's ratio |
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| Title |
|---|
| FWD弯沉盆几何参数与路面结构强度关系分析;杨庆振 等;山东交通科技(第05期);全文 * |
| 沥青路面反算模量与沥青混合料动态模量的关系;宋小金;土木工程学报;第52卷(第4期);全文 * |
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