JPH0860611A - Repairing method for asphalt pavement - Google Patents

Abstract

PURPOSE: To quickly determine the extend of repairing and to perform the work of repairing an asphalt pavement most suitably, by respectively finding rediual strength and an elastic modulus of a subgrade through a deflection remainder and a deflection value of an asphalt mixture layer. CONSTITUTION: Rediual strength TAO is found through a deflection remainder of an asphalt mixture layer according to the following formula. TAO=-28.5log (Do-Dx)+11.1 where TAO is the product of the distance from the loading point to the measurement point by the residual strength at the measurement point, Do is the deflection value at the loading point, and Dx is the product of the distance from the loading point to the measurement point by the deflection value at the measurement point. After that, the elastic modules Ex of the subgrade is found through the deflection value of the asphalt mixture layer according the following formula. Ex=10/Dx where Ex is the product of the distance from the loading point to the measurement point by the elastic modulus of the subgrade of the measurement point. After that, the improving of the subgrade, the replacing of the asphalt mixture layer, the overlaying thereof, or the partial repairing thereof is selected on the basis of the position shown in a diagram whose axes are measured values of the residal strength TAO and the elastic modulus Ex.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of repairing a pavement having an asphalt mixture layer. More specifically, for an asphalt pavement, typically an asphalt pavement, the degree of repair (construction method) is quickly determined based on the residual strength TAO of the asphalt mixture layer and the roadbed elastic modulus Ex, and the optimum repair work is performed. Regarding the repair method that enables it.

[0002]

2. Description of the Related Art Conventionally, repair of asphalt paved roads has been
In many cases, the degree of cracks and wear on the road surface is investigated by visual observation and measurement, and the repair location and repair method are determined based on experience. , The best repair work is not always done. In addition, it is also possible to partially sample the pavement surface to check the degree of deterioration, but it is not possible to carry out repair work quickly because sampling and analysis take time and labor. Moreover, it is often difficult to select an appropriate repair method because the survey area is partially limited.

[0003]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned conventional problems in the conventional method for repairing asphalt pavement, wherein the method for repairing the asphalt pavement can be easily determined, and the optimum repair work can be performed quickly. The purpose is to provide a repair method that can be carried out.

[0004]

According to the present invention, there is provided a method for repairing an asphalt pavement having the following structure. (1) (b) The residual degree TAO is calculated from the difference in deflection of the asphalt mixture layer according to the following equation (1), and TAO = −28.5 log (Do−Dx) +11.1 (1) where TAO is the distance from the loading point. Residual strength at a distance of x, Do is the amount of deflection at the loading point, Dx is the amount of deflection at a distance x from the loading point, and (b) the amount of deflection of the asphalt mixture layer according to the following equation (2) Ex is calculated as: Ex = 10 / Dx (2) where Ex is the roadbed elastic modulus at a distance x from the loading point, and Dx is as described above, (c) the residual strength TAO of the asphalt mixture layer and the roadbed. Based on the position occupied by the measured values of the residual strength TAO and the roadbed elastic modulus Ex in the plane coordinate system with the elastic modulus Ex as the coordinate axis, it is necessary to select the roadbed improvement, asphalt mixture layer replacement, overlay or partial repair. A characteristic method for repairing asphalt pavements.

Further, according to the present invention, there is provided the following repair method embodying the above repair method. (2) The residual strength TAO of the asphalt mixture layer and the plane coordinates with the roadbed elastic coefficient Ex as coordinate axes are the lower limit value (L) of the roadbed elastic coefficient, and the target reference value (L1) of the remaining strength TAO at the lower limit value. And setting reference value (L2), setting value of roadbed elastic modulus (S)
It is divided into the area (〓) (〓) (〓) (〓) by the target standard value (S1) and the setting standard value (S2) of the remaining strength TAO in, and the area (〓) is the above lower limit (L). The range and area (〓) below is the range on the coordinate axis connecting the set reference value (L2) and (S2) of the residual strength TAO and the range and area above the set value (S) below the target reference value (S2). (〓) is the range outside the area (〓),
The range of the residual strength TAO on the coordinate axis connecting the target reference value (L1) and (S1) and the range below the target reference value (S1) above the set value (S), the area (〓) is from the area (〓) The outer range,
Area (〓) is roadbed improvement, area (〓) is asphalt mixture layer replacement, area (〓) is overlay or partial repair, area (〓) is pavement strength fulfillment range, remaining strength TAO and road The repair method according to (1) above, in which the repair method is selected according to the division of the area occupied by the measured value of the floor elastic modulus Ex.

Further, according to the present invention, there is provided the following repair method in which the accuracy of the above repair method is improved. (3) The average temperature Tave of the asphalt mixture layer is calculated according to the following equation (3), and Tave = (aTsu + bTair + c) αZβ (3) where Tave is the average temperature of an arbitrary layer thickness, Tsu is the road surface temperature, Tair is the temperature, a, b, c, α, β are correction factors, and based on the average temperature Tave, temperature correction of the elastic coefficient of the asphalt mixture layer at the standard temperature is performed according to the following equation (4), and Est = Eave × 10 ^{[-0.0184x ( 20-Tave)]} (4) where Est is the elastic coefficient at standard temperature, Eave is the elastic coefficient at average temperature, and Tave is the deflection of the asphalt mixture layer obtained based on the temperature-corrected elastic coefficient as described above. The repair method of the above (1) using the difference.

[0007]

[Detailed Description] The flow chart of FIG. 1 shows the procedure for carrying out the repair method of the present invention. The repair method of the present invention is based on the residual strength TAO derived from the difference in the amount of flexure of the asphalt mixture layer (hereinafter abbreviated as the ascon layer) (bending difference) and the roadbed elastic coefficient Ex derived from the amount of flexure. Judge the degree and select the most suitable repair work.

(1) Method of Measuring Deflection A method for measuring the amount of deflection of the Ascon layer is to apply an impact load to the pavement surface and measure the amount of deflection generated at this time by using a falling weight deflectometer (Falling Weight).
Deflectometer: Hereinafter abbreviated as FWD. The non-destructive measurement method by () is known. The outline of the measuring method by this FWD is shown in FIG. As shown in the figure, the measuring method is to drop the weight 12 on the loading plate 11 installed on the road surface 10, and to measure the impact load by the pressure gauge 13 provided on the loading plate and the deflection sensors 14 installed at a plurality of points on the road surface. Measure the amount of deflection. According to this method, a large amount of data can be easily obtained in a short time, and by accurately evaluating the structure of the pavement, (1) estimation of the same section of the pavement structure, (2) pavement composition Estimating elastic modulus of layer, (3) Estimating cause of failure, (4)
It is possible to estimate the pavement life. The repair method of the present invention is a method that allows accurate structure evaluation of pavement and selection of an optimum repair construction method in a short time, and can be easily performed by using an FWD measuring device.

(2) Average Temperature of Ascon Layer Since the amount of deflection of the Ascon layer is greatly influenced by temperature, it is desirable to correct the temperature of the measured value. Conventionally,
Although the temperature of the deflection is corrected using the road surface temperature at the time of deflection measurement, in order to strictly compare and evaluate the deflection and the elastic coefficient of the Ascon layer at the standard temperature, the average temperature of the Ascon layer is calculated and the temperature is corrected. It is desirable to do. According to the study by the present inventors, the average temperature at a constant depth of the ascon layer can be calculated according to the following equation (5). Tave = aTsu + bTair + c (5) where Tave is the average temperature (° C) of any layer thickness, Tsu is the road surface temperature (° C), Tair is the temperature (° C), and a, b, c are correction factors,

The above temperature equation (5) is derived as follows.
As shown in FIGS. 3 (A) and 3 (B), a thermocouple for measuring the internal temperature of the Ascon layer is provided on the pavement 31 constructed for temperature measurement.
4 of 32 were embedded in the layer thickness of the ascon layer 13 cm. The air temperature was measured by a thermocouple in a hundred-leaf box located 2 m above the ground, and the road surface temperature was measured by using a contact thermometer. According to the measured values, the road surface temperature and the temperature of the thermocouple at a pavement depth of 0.5 mm are almost the same. In addition, using the temperature data of the thermocouple at each buried depth,
When the average temperature is calculated by integral averaging, the temperature at a depth of 7 cm and the calculated average temperature are almost the same. From this, the temperature at a depth of 7 cm can be regarded as the average temperature.

Next, an example of the temperature distribution in the Ascon layer for one day is shown in FIG. Further, since the temperature distribution of one day differs depending on the time, the temperature distribution of each month at the same time is shown in FIG. In the temperature distribution at the same time, there are some months with similar distribution shapes. As a result, it can be seen that the annual temperature group can be classified into three types. Using the temperature of 7 cm depth as the objective variable and the temperature and the road surface temperature as explanatory variables, divide the year into three groups, and calculate the multiple regression equation as one hour group from 6:00 to 18:00. Equation (5) is obtained.

FIG. 6 shows the average temperature calculated based on the actual measurement data of the road surface temperature and the temperature equation (5) for the Ascon layer for one day. As shown in the figure, the result calculated by the temperature equation and the average temperature at the depth of 7 cm are in good agreement. This temperature equation (5) is for a pavement with an Ascon layer having a thickness of 13 cm, and a correction term is added to obtain the average temperature of the Ascon layer having an arbitrary thickness. It is known that the temperature distribution shape in the asphalt mixture does not change even if the thickness of the ascon layer is different, so that the temperature can be calculated by regarding the thermal diffusivity as constant. Then, based on this, the temperature equation (3) having the temperature correction term shown in the following equation is obtained. Tave = (aTsu + bTair + c) αZβ (3) Here, Tave is the average temperature of an arbitrary layer thickness, Tsu is the road surface temperature, Tair is the temperature, and a, b, c, α, β are correction coefficients, and this average temperature equation (5 FIG. 7 shows the result of comparison between the temperature calculated by) and the measured value of the average temperature. This graph is an example where the layer thickness of the ascon layer is 20 cm, but the average square error is 1.5 ° C, and the results are in good agreement.

(3) Temperature correction of elastic coefficient of asphalt mixture layer Temperature correction of elastic coefficient of the ascon layer can be performed based on the average temperature Tave of the ascon layer obtained as described above. FIG. 8 shows the relationship between the average temperature Tave of the ascon layer and the elastic coefficient of the ascon layer obtained by the inverse analysis from the FWD measurement results. Generally, the relationship between the average temperature of the ascon layer obtained in the indoor test and the elastic coefficient is approximated by a higher-order curve because the elastic coefficient significantly decreases on the high temperature side. It can be seen that the elastic modulus of the layer does not decrease extremely at high temperature, and the relationship between the two can be approximated by a linear line.

Using the slope of the regression line of the average temperature and elastic coefficient of the Ascon layer shown in FIG. 8, the elastic coefficient Eave of the Ascon layer at the average temperature Tave is calculated to obtain the elastic coefficient Est of the Ascon layer at the standard temperature of 20 ° C. Calculation formula of elastic modulus shown in the following formula
(4) is obtained. Est = Eave × 10 ^{[-0.0184x (20-Tave)]} (4) Here, Est is the elastic coefficient at the standard temperature, Eave is the elastic coefficient at the average temperature, and Tave is as described above. Highly accurate determination can be performed by obtaining the deflection amount and the deflection difference of the Ascon layer based on the elastic coefficient of the Ascon layer at the standard temperature (usually 20 ° C.) obtained by this temperature correction.

(4) Measurement of deflection difference of ascon layer In the repairing method of the present invention, the residual strength TAO obtained from the deflection difference of the asphalt mixture layer is used as one of the criteria for judging the repairing method according to the following equation (1). To do. TAO = −28.5 log (Do−Dx) +11.1 (1) Where, TAO is the residual strength at the position x distance from the loading point, Do is the amount of deflection of the loading point, and Dx is the distance x from the loading point. It is the amount of deflection of the position.

FIG. 9 schematically shows a load distribution and a bending curve when a load is applied to an actual road. When a load is applied to the pavement, the vertical stress is dispersed conically around the loading point of the load. Here, it can be considered that the shape of the bending curve in the figure is determined by the total amount of elastic compression of each pavement layer. Further, the load influence line is a boundary line where vertical compression strain hardly occurs outside the load influence line, and the amount of deflection Dx at a position away from the loading point by distance x is related to a certain depth or more inside the load influence line. Only the amount of compression of the layers. On the other hand, immediately below the loading point, all layers are inside the load-influence line, so the sum of the elastic compression amounts of all layers appears as the deflection amount Do immediately below the loading point.
In addition, it can be considered that the difference between the adjacent bending amounts represents the elastic compression amount of the layer located in the middle.

The pavement deteriorates due to repeated traffic loads, seasonal fluctuations, etc., leading to destruction. The number of standard wheel loads up to the point of failure is called the allowable number of loaded wheels, and if the load is constant, the stress / strain that occurs will differ due to the difference in the structural strength of the pavement. From this, it is possible to determine the bending limit value for each traffic volume level from the relationship between the bending amount just below the loading point indicating the strength characteristics of the pavement including the roadbed and the allowable number of loaded wheels. FIG. 10 shows a plot of the relationship between the deflection amount Do immediately below the loading point and the allowable loading wheel number converted to 49 kN (5 tf) in a log-log graph. According to this graph, those with good road surface properties and those with linear cracks are linearly dispersed. Here, deflection Do and 49kN (5tf) just below the loading point on a good road surface
The correlation coefficient of the converted allowable number of loaded wheels is -0.89, and both have a linearly proportional correlation. This solid line is the regression line for all data. Here, the 85% tile value of Do (D
85 = regression line + 1.04σ), the dotted line shown in the figure is obtained. It can be judged that this dotted line is the boundary of the deflection where the road surface is good or linear cracks occur.
As a result, the dotted line in the figure can be regarded as the limit line of flexure Do immediately below the loading point (generation of linear crack). The formula of this limit line is shown in the following formula (6). log (Domax) = − 0.23 log (N5) (6) Where, Domax is the critical deflection (mm), N5 is the allowable load number (times) converted to 49kN (5tf) obtained from the tensile strain of the bottom surface of the Ascon layer. Is.

As an evaluation index showing the structural characteristics of the Ascon layer, the product of the elastic coefficient E1 of the Ascon layer and the layer thickness h1 (hereinafter,
Attention is paid to the layer coefficient of the Ascon layer) and the deflection difference Do-Dx. This relationship is shown in FIG. The plot in the figure has a unique relationship between the layer thickness of the asphalt mixture layer of 5 and the layer coefficient of the ascon layer. That is, if the layer thickness of the ascon layer is known, the elastic coefficient of the ascon layer can be calculated from the deflection difference Do-Dx. This relationship is expressed by the following equations (7), (8)
Shown in log (E1 × h1) = − 0.91 log (Do−Dx) +1.80 (7) or E1 = 63 × (Do−Dx) ^−0.91 / h1 (8) where E1 is the elastic coefficient of the Ascon layer ( MPa), h1 is the layer thickness of the ascon layer (cm), Do-Dx is the amount of deflection at the loading point and the distance x
This is the difference (mm) in the amount of bending at distant positions.

The deflection difference Do-Dx is the amount of deformation of the pavement,
Since it is considered to represent the strength of the pavement, the relationship between the equivalent conversion thickness TA and the deflection difference Do-Dx at the time of the design of the survey route less than 3 years after the start of service is obtained, and the result of FIG. 12 is obtained. The relationship between the two is almost linear on the semi-logarithmic graph, and the correlation coefficient thereof has a strong correlation of -0.91. In addition, most of the plots in FIG. 12 are less than one year after starting operation,
Part of the data includes pavement with good road surface less than 3 years after starting operation. The confidence interval with a reliability of 90% is in the range of the dotted line in the figure, and has a width of TA ± 1.9 cm on average. From the above results, the regression equation of the deflection difference Do-Dx and TA is expressed by the following equation (9). TA = −28.5 log (Do−Dx) +11.1 (9) Where, TA is the equivalent thickness, Do is the deflection of the loading point, Dx
Is the amount of flexure at a distance x from the loading point. The above equivalent thickness TA is the residual strength TAO that the pavement currently has.
Equivalent to.

(5) Calculation of hearth elastic modulus Next, due to the stress distribution of the load applied to the pavement, the flexure at the position away from the loading point is hardly affected by the pavement thickness and depends only on the bearing capacity of the roadbed. (See FIG. 9).
Therefore, when the relationship between the flexure amounts of the elastic coefficient Ex and Dx of the roadbed is obtained, the result of FIG. 13 is obtained. The graph of FIG. 13 shows the design CBR test values 3, 4, 6, according to the traffic volume classifications A, B, C, and D shown in the standard design criteria for asphalt pavement.
With 8 and 12 pavement configurations (20 types in total),
Examine D1500 (deflection amount at a point 1500mm away from the loading point) when varying from 100 to 4000kgf / c〓, and load 5tf
7 is a graph showing the relationship between the roadbed elastic modulus and the amount of flexure at the time. The relationship between the two changes linearly, and the slope is almost -1.
Is. From this, the elastic coefficient of the roadbed can be calculated based on the amount of deflection. This calculation formula is shown in the following formula (10). Ex = 10 / Dx (10) where Ex is the roadbed elastic coefficient at a position separated by a distance x from the loading point, and Dx is as described above.

(6) Selection of repair method The repair method is selected based on the residual strength TA0 and the roadbed elastic coefficient Ex which represent the mechanical characteristics of the current pavement structure, and the traffic volume is added to the selection. It is preferable. As a specific example, a conceptual diagram of a repair method selection chart is shown in FIG. This chart shows the residual strength T of the asphalt mixture layer.
It consists of AO and plane coordinates with the roadbed elastic coefficient Ex as coordinate axes, and the lower limit value (L) of the roadbed elastic coefficient, the target reference value (L1) and the set reference value (L2) of the remaining strength TAO at the lower limit value, Area (〓) (〓) according to the target reference value (S1) and the setting reference value (S2) of the remaining strength TAO at the set value (S) of the roadbed elastic modulus
It is divided into (〓) and (〓). Here, the area (〓) is a range less than the lower limit (L) above, and the area (〓) is the range on the coordinate axis connecting the set reference value (L2) and (S2) of the residual strength TAO and the target reference value ( It is a range that is less than S2) and exceeds the set value (S) above.
The area (〓) is the area outside the area (〓), the range on the coordinate axis connecting the target reference value (L1) and (S1) of the residual strength TAO, and the above setting below the target reference value (S1). The range exceeds the value (S), and the area (〓) is the area outside the area (〓). Here, the area (〓) is the range and area where roadbed improvement is required.
(〓) is the range that requires replacement of the Ascon layer, the area (〓) is the range that requires overlay or partial repair, and the area (〓) is sufficient for the pavement strength, and can be treated individually according to damage. This is a sufficient range. In this plane coordinate, residual strength TAO
The repair method is selected according to the division of the area occupied by the measured value of the roadbed elastic modulus Ex.

At the above coordinates, the lower limit value of the roadbed elastic modulus
The target reference value (S1) and setting reference value (S2) of the eye strength TAO of the remaining strength TAO in (L) are preferably set according to the traffic volume. Specific examples of this are shown in FIGS. Each figure shows the above value for each design traffic volume category known as a design standard for asphalt pavement. FIG. 15 is a traffic volume A, FIG. 16 is a traffic volume B, FIG. 17 is a traffic volume C, and FIG. Is the case of traffic volume D.

Incidentally, the relationship between the roadbed elastic modulus and the CBR test value relating to the roadbed supporting force is that Ex (kgf / c〓) = 100 to 200CBR {Ex (MPa) for cohesive soil or sandy soil according to previous studies. = 10 ~
20CBR}, gravel mixed soil, etc. Ex (kgf / c〓) = 50-100C
It is known that BR {Ex (MPa) = 5 to 10 CBR}. The repair method selection coordinates shown in the figure are the median values of cohesive soil and sandy soil, Ex (kgf / c〓) = 150 CBR {Ex (MPa) =
It is based on the relational expression of 15CBR}.

FIG. 19 shows an application example of the repair method of the present invention. In this example, the roadbed elastic modulus E determined by the FWD device
Is 40MPa, target TA is 27cm, Do-after temperature correction
The residual strength TAO determined from D1500 is 14 cm. If you plot the measured value (○) before repair on this coordinate,
The measured values are located in the area (〓) as shown in the figure, and it can be seen that repairs of the replacement method are necessary. Therefore, repair was carried out by a method of providing a recycled CAE roadbed, which is a similar repair method. After one month from the repair, the amount of flexure of the repaired part was measured, and the residual strength TAO and the roadbed elastic modulus Ex were calculated and plotted on the coordinates (marked by □), the residual strength TAO was recovered to 27 cm, and the road was recovered. It was confirmed that the floor elastic modulus Ex was also larger than that before the repair, and the measured value was located in the area (〓), which satisfied the pavement strength. The application examples of the present invention are summarized in Table 4. In each of the construction examples, the same results as in the above application example were confirmed before and after the repair.

[0025]

[Table 4]

As described above, according to the method of the present invention, the degree of repair can be easily discriminated based on the flexure amount and flexure difference of the Ascon layer, and the optimum repair work can be carried out promptly. In addition to the repair method of the present invention, as a method related thereto, the soundness of the pavement, the elastic modulus of each layer of the pavement can be obtained, and the structure of the pavement can be evaluated. Hereinafter, this method will be described.

(Soundness of pavement) Table 1 shows the boundary values at which the quality of pavement is classified according to the design traffic volumes A to D, using the above-mentioned deflection amount and deflection difference as indexes. This value is 5tf (49kN) equivalent number of wheels corresponding to 10 years of design period for each traffic segment of traffic volume A, traffic volume B, traffic volume C, and traffic volume D.
Assuming 35 million times, 5 tf of each flexure evaluation index
(49kN) The average value of the deflection (Dave) in the converted number of wheels is good.
The boundary value is (good) and normal (normal), and the deflection average value + standard deviation (Dave + σ) is used as the boundary value between poor (normal) and normal (normal). From the results in Table 1, it can be seen that the soundness of the pavement can be classified into three ranks based on the deflection at the standard temperature of 20 ° C.

[0028]

[Table 1]

(Elastic Modulus of Each Layer of Pavement) Structural analysis of pavement is generally carried out by using the multilayer elasticity theory. When the number of layers is n using this multilayer elasticity theory, it is possible to obtain the stress and strain at any position in the ground if the following four types of values are known. As for, it suffices if any two of these three values are known. Elastic modulus of material forming each layer (E1 to En) Poisson's ratio of material forming each layer (ν1 to νn) Thickness of each layer (h1 to hn) Magnitude of load, contact radius, contact pressure (P, a) Depth (z) and radial distance by setting the above values
Normal stress (σz) at any point in (r), radial stress
(σr), tangential stress (σt), shear stress (τrz), vertical displacement
(ω), radial displacement (υ) are calculated.

As a method of estimating the elastic coefficient of each layer in a multilayer structure, a method is known in which the difference between the measured bending and the calculated bending obtained by the multilayer elastic calculation is minimized. This method first sets the elastic coefficient, Poisson's ratio, etc. of each layer,
Calculate the deflection. Compare the calculated deflection and the measured deflection, and if the difference between the two is larger than the specified error range, or if the value of the evaluation function set for the judgment of convergence is larger than the set value, the difference between the two is reduced. This is a method in which the elastic coefficient is modified and the calculation of deflection is repeated. In addition, an elastic coefficient inverse analysis program LMBS, which uses the modified Gauss-Newton method for the optimization method using the least squares method, has been announced. Is shown in the following equation (11).

[0031]

[Formula 11]

Inverse analysis of the elastic modulus of each pavement layer has been performed up to now by a method using a nomograph, a pattern search method, a least squares method, or the like. In case of least squares analysis,
Depending on the initial value of the elastic coefficient to be input, the number of calculations until the solution converges may be large, or the solution may diverge in some cases. Therefore, with the pavement structure shown in FIG. 20 as a reference, the elastic coefficient input as the initial value of the inverse analysis program can be obtained as follows. That is, as the value of the elastic coefficient input as the initial value of the inverse analysis program, a completely unknown value should not be randomly selected, but a value within a range considered to be appropriate must be selected. Therefore, the elastic coefficient can be derived by further narrowing down the initial value of the elastic coefficient using the bending evaluation index. A good result is obtained by evaluating the flexural residual, which represents the degree of coincidence of the elastic coefficients, using equation (11).

If the layer thickness h1 of the asphalt mixture is known from the above-mentioned deflection difference Do-D200, the elastic modulus E1 of the asphalt mixture layer can be obtained, and the roadbed elastic modulus E4 can be obtained from D1500. Here, if the elastic coefficients E2 and E3 of the roadbed layer are calculated, the elastic coefficient of each pavement layer can be calculated. Therefore, with respect to the FWD measurement values at about 300 points, the elastic coefficients E2 and E3 of the roadbed layer are used as the target variables, and the elastic modulus E other than the roadbed layer, layer thickness h, deflection of each sensor D, deflection between each sensor By performing multiple regression analysis using the difference as the dependent variable, the following multiple regression equation (12) is obtained.
In this case, since the strain level generated in the roadbed layer varies depending on the thickness of the ascon layer, the elastic modulus E of the roadbed layer E
For 2 and E3, the multiple regression equation was examined for each layer thickness h1 of the ascon layer, and the case of using the granular roadbed for the upper layer and the case of performing the asphalt stabilization treatment were examined. Ei = f (E1, E4, hi, Di, Di-Dj) (12) where Ei is the elastic modulus (i = 2,3) (MPa) of the roadbed layer, and E1 is the elastic modulus (MPa of the asphalt mixture layer. ), E4 is the elastic modulus of the roadbed (MPa), hi is the layer thickness of each layer (i = 1 to 3) (m), Di is the deflection at each position (μm), and Di-Dj is the deflection difference (μm). is there.

Table 2 shows the multiple regression coefficients when the upper roadbed is granular crushed stone (Unbound Base), and Table 3 shows the multiple regression coefficients when the upper roadbed is asphalt stabilization (Bound Base).
Numerical values in the table indicate partial regression coefficients obtained by dividing the values of each dependent variable by the average value and normalizing. From the table, it can be seen that in the calculation of E2 and E3, the variable having a large partial regression coefficient differs depending on the thickness of the asphalt mixture, and the thicker the mixture layer, the more important the deflection and the difference in deflection at the position away from the loading point.

[0035]

[Table 2]

[0036]

[Table 3]

The asphalt mixture has a modulus of elasticity of 6000 (MP
a), the elastic coefficient of recycled CAE roadbed is 2000 (MPa), the elastic coefficient of cut crushed stone is 150 (MPa), and the initial value of elastic coefficient and the value obtained by the above regression equation (12) FIG. 21 shows a comparison when the initial values are set. From this figure, when the regression estimated value based on the deflection is used as the initial value of the elastic coefficient, the residual sum of squares (RMS) of the initial value is small and the number of times of convergence is small. Therefore, according to the above regression equation (12), It can be seen that the elastic modulus of each pavement layer can be calculated in a short time.

[0038]

According to the repair method of the present invention, the extent of repair can be easily determined by the residual strength and the roadbed elastic coefficient based on the flexure amount and flexure difference of the Ascon layer, and the optimum repair work can be carried out quickly. be able to. Further, the repairing method can be selected with higher accuracy by correcting the elastic coefficient of the ascon layer with temperature.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for carrying out a repair method of the present invention.

FIG. 2 is a conceptual diagram of a measurement system using an FWD device.

FIG. 3A is a schematic cross-sectional view of a pavement for temperature measurement,
(B) Layout of thermocouple

[Figure 4] Temperature distribution map in the Ascon layer for 1 day

[Figure 5] Monthly temperature distribution map in the Ascon layer

[Fig.6] Temperature change diagram in the Ascon layer for 1 day

[Figure 7] Comparison graph of calculated temperature and average temperature in Ascon layer

FIG. 8 is a graph showing the relationship between the average temperature of the ascon layer and the elastic modulus.

FIG. 9 is a schematic explanatory view showing a load distribution and a bending curve inside the pavement.

FIG. 10 is a graph showing the relationship between the deflection amount Do immediately below the loading point and the 49kN (5tf) allowable loading wheel number.

FIG. 11 is a graph showing the relationship between the difference in deflection, the thickness of the Ascon layer, and the product of the elastic modulus.

FIG. 12 is a graph showing the relationship between the deflection difference and the equivalent thickness.

FIG. 13 is a graph showing the relationship between the amount of flexure of D1500 and the roadbed elastic modulus Ex.

[Fig. 14] Repair method selection coordinates

[Fig.15] Repair method selection coordinates for traffic A

[Fig. 16] Repair method selection coordinates for traffic volume B

Fig. 17 Coordinates for selecting repair method for traffic volume C

[Fig. 18] Repair method selection coordinates for traffic volume D

FIG. 19: Actual measurement coordinates for repair method selection

FIG. 20 is a schematic diagram showing a four-layer structure of pavement.

FIG. 21 is a comparison graph of the number of convergences when the initial value of the elastic coefficient based on the calculation formula and the reference value are used.

[Explanation of Codes] 10-Road Surface 11-Loading Plate 12-Weight 13-Pressure Gauge 14-Bend Sensor 31-Pavement 32-Thermocouple

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Maruyama 1603-1 Kamitomioka-cho, Nagaoka-shi, Niigata Nagaoka University of Technology

Claims (4)

[Claims] (A) The residual strength TAO is calculated from the deflection difference of the asphalt mixture layer according to the following formula (1), and TAO = -28.5 log (Do-Dx) +11.1 (1) where TAO is the loading point. Residual strength at a distance x from, Do is the deflection at the loading point, Dx is the deflection at a distance x from the loading point, (b) From the deflection of the asphalt mixture layer according to the following equation (2), The elastic modulus Ex is calculated as follows: Ex = 10 / Dx (2) where Ex is the roadbed elastic modulus at a distance x from the loading point, and Dx is, as described above, (c) the residual strength TAO of the asphalt mixture layer and Residual strength TAO in plane coordinates with the roadbed elastic modulus Ex as the coordinate axis
And the position occupied by the measured value of the roadbed elastic modulus Ex,
A method of repairing an asphalt pavement, which comprises improving a roadbed, replacing an asphalt mixture layer, and selecting overlay or partial repair. 2. The residual strength TAO of the asphalt mixture layer and the plane coordinates with the roadbed elastic modulus Ex as coordinate axes are the lower limit value (L) of the roadbed elastic coefficient, and the residual strength TAO at the lower limit value.
Target reference value (L1) and setting reference value (L2), target reference value (S1) of the remaining strength TAO at the set value (S) of the roadbed elastic coefficient
It is divided into areas (〓) (〓) (〓) (〓) by the setting reference value (S2), the area (〓) is the range below the lower limit (L) above, and the area (〓) is the residual strength TAO. Range of the coordinate axis connecting the set reference value (L2) and (S2) and the set value above the target reference value (S2)
The range beyond (S), the range (〓) is outside the range (〓), the range on the coordinate axis connecting the target reference value (L1) of residual strength TAO and (S1), and the target reference value ( Area (〓) is outside of area (〓), area (〓) is road improvement, area (〓) is asphalt mixture layer strike Instead, the area (〓) is each area of overlay or partial repair, and the area (〓) is each area of pavement strength fulfillment, and the repair method is selected according to the division of the area occupied by the measured values of the residual strength TAO and the roadbed elastic coefficient Ex. The repair method according to claim 1. 3. An average temperature Tave of the asphalt mixture layer is calculated according to the following equation (3), and Tave = (aTsu + bTair + c) αZβ (3) where Tave is an average temperature of an arbitrary layer thickness, Tsu is a road surface temperature, and Tair is Temperature, a, b, c, α, β are correction coefficients, and the elastic coefficient of the asphalt mixture layer at the standard temperature is temperature-corrected according to the following equation (4) based on the above-mentioned average temperature Tave, and Est = Eave × 10 ^{[-0.0184 x (20-Tave)]} (4) Here, Est is the elastic coefficient at the standard temperature, Eave is the elastic coefficient at the average temperature, and Tave is the asphalt mixture layer obtained based on the temperature-corrected elastic coefficient as described above. The repair method according to claim 1, wherein the flexure difference is used. 4. The lower limit (L) of the roadbed elastic modulus in a plane coordinate system having the residual strength TAO of the asphalt mixture layer and the roadbed elastic coefficient Ex as coordinate axes, and a target reference value of the remaining strength TAO at the lower limit (L). L1) and the set reference value (L2), the target reference value of the above remaining strength TAO at the set value (S) of the roadbed elastic coefficient
The repair method according to claim 1, wherein (S1) and the set reference value (S2) are determined according to the traffic volume.