JP2014062356A - Method for evaluating damage to pavement body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating damage to a pavement body, which enables a simple and inexpensive evaluation of the damage to the pavement body.SOLUTION: A method for evaluating damage to a pavement body, in which the damage to the pavement body is evaluated, includes: a measurement step S1 of measuring vertical acceleration in such a manner that a vehicle having an installed vibration measuring instrument travels on the pavement body; and a corrective dynamic load coefficient computing step S2 of computing a corrective dynamic load coefficient by substituting a value of the measured vertical acceleration into a regression equation precomputed by a dynamic load test.

Description

  The present invention relates to a damage evaluation method for a pavement that evaluates damage to the pavement.

  The pavement is subject to structural damage such as cracking and rutting due to long-term vehicle traffic and deterioration over time. Such damage causes a decrease in the stability of running performance and causes of noise. Therefore, it is necessary to periodically examine the pavement and examine whether repair is possible.

  A FWD (Falling Weight Deflectometer) shown in Non-Patent Document 1 is known as an apparatus for evaluating damage to a pavement. FWD can evaluate the damage of a pavement by dropping a weight on the road surface and simultaneously measuring the amount of deflection generated on the pavement at a plurality of points. As other methods for evaluating the damage of the pavement, a Benkelman beam test, a flat plate loading test, and the like are known.

Japan Road Construction Industry Association, FWD (pavement structure evaluation device), [online], December 26, 2011 search, Internet (URL: http://www.dohkenkyo.net/pavement/kikai/fwd.html )

  However, the conventional evaluation methods such as FWD have the advantage of being able to grasp the degree of damage of the pavement at the measurement location, but have the problem that the measurement takes time. In addition, the conventional evaluation method such as FWD has a problem that a dedicated vehicle must be used and traffic regulation is required, and the cost of the apparatus is high.

  The present invention has been developed from such a viewpoint, and an object of the present invention is to provide a pavement damage evaluation method that can easily and inexpensively evaluate pavement damage.

  In order to solve such a problem, the present invention is a damage evaluation method for a pavement that evaluates damage to the pavement, and the vehicle on which the vibration measuring device is installed travels on the pavement, A measuring step for measuring acceleration, a corrected dynamic load factor calculating step for calculating a corrected dynamic load factor by substituting the measured vertical acceleration value into a regression equation calculated in advance by a dynamic load test, and In the dynamic load test, the regression equation is obtained by dividing the dynamic load when a vehicle equipped with a vibration measuring instrument travels a predetermined position at a plurality of predetermined speeds by the axle load of the vehicle. It is obtained from the correlation between a plurality of corrected dynamic load coefficients obtained in this way and a plurality of vertical accelerations at the predetermined position obtained from the vibration measuring instrument.

  The applicant has found that the corrected dynamic load coefficient and the amount of flexure of the pavement have a high correlation based on the test results and analysis results obtained from tests using vehicles. Thereby, the damage of the measured pavement can be evaluated by calculating the corrected dynamic load coefficient from the vertical acceleration of the vehicle that has traveled. In addition, it is not necessary to use a dedicated vehicle, and it is only necessary to install a vibration measuring instrument on a normal vehicle and run it, so that traffic regulation is not imposed and the cost of the apparatus can be reduced. Further, by using the corrected dynamic load coefficient, the evaluation can be performed regardless of the type of vehicle that travels. “Vehicle axle weight” means a load value at a measurement position when the vehicle is stationary.

  Further, it is preferable to include a comparison step of comparing the reference value of the allowable deflection amount predetermined in the pavement with the calculated corrected dynamic load coefficient.

  The degree of damage of the pavement can be grasped by comparing the calculated corrected dynamic load coefficient with the reference value of the allowable deflection amount. For example, it is possible to predict changes in pavement damage by comparing the corrected dynamic load coefficient calculated for each service year and the reference value of the allowable deflection amount. The “reference value of the allowable deflection amount” is a value set in advance based on the planned traffic volume set for the pavement.

  In the measurement step, an imaging unit is installed in the vehicle and travels on the pavement, and the captured image of the pavement acquired by the imaging unit and the measured vertical acceleration are displayed in association with each other. It is preferable to display on the means.

  According to this method, since the captured image of the pavement at a position corresponding to the measured vertical acceleration can be seen, damage to the pavement can be visually evaluated.

  According to the damage evaluation method for a pavement according to the present invention, damage to the pavement can be evaluated easily and inexpensively.

It is a block diagram which shows the damage evaluation apparatus of the pavement which concerns on this embodiment. It is a schematic diagram which shows the installation location of the vibration measuring device which concerns on this embodiment. It is a table | surface which shows the reference value of allowable deflection amount. It is a flowchart which shows the damage evaluation method of the pavement which concerns on this embodiment. It is a figure which shows the display form of the graph 1 mode which concerns on this embodiment. It is a figure which shows the display form of the graph 2 mode which concerns on this embodiment. It is a flowchart which shows the examination flow which concerns on verification. It is a schematic diagram which shows the hump used for a dynamic load test. It is a graph which shows the relationship between the vertical acceleration and dynamic load in a dynamic load test. It is a graph which shows the relationship between the vertical acceleration in a dynamic load test, and a correction dynamic load coefficient. It is a schematic diagram which shows a QC model. It is a graph which shows the relationship between the measured value at the time of drive | working a hump, and PSD of a model calculation value. It is a table | surface which shows a calculation profile list. It is a graph which shows the relationship between a road surface profile and driving speed. It is a graph which shows PSD of the road surface profile of route number 6. It is a table | surface which shows the outline | summary of examination route. It is a figure which shows the survey outline of each route. It is a graph showing a modified and serviced lives dynamic load factor and D ₀ deflection of relationship. Fixed is a graph showing the relationship between the dynamic load factor and D ₀ deflection amount. It is a graph which shows the relationship between an asphalt elastic modulus and CBR of a roadbed. It is a block diagram which shows the damage evaluation apparatus of the pavement which concerns on 2nd embodiment. It is a figure which shows an example of the image processing mode which concerns on 2nd embodiment.

[First embodiment]
A first embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the damage evaluation apparatus 1 for a pavement according to the present embodiment is mainly composed of a vibration measuring instrument 2 and a controller 3 installed in a vehicle. The pavement damage evaluation apparatus 1 is an apparatus that can evaluate the damage of a pavement that has traveled by running the vehicle.

  The vibration measuring instrument 2 is installed in the vicinity of the axle V1 of the vehicle V as shown in FIG. In order to eliminate the influence of other devices such as the suspension of the vehicle V, it is preferable to install the vibration measuring instrument 2 on or near the axle V1. The vibration measuring instrument 2 is a vibration measuring unit that measures the acceleration in the vertical direction of the axle V1 in time series. The vibration measuring instrument 2 and the controller 3 are electrically connected via a cable.

  Although not specifically shown, the vibration measuring instrument 2 includes an acceleration sensor, an amplifier that amplifies the analog signal measured by the acceleration sensor, and an A / D that converts the analog signal amplified by the amplifier into digital data. It consists of a converter. Vibration acceleration data digitized by the A / D converter is supplied to the controller 3 via a cable.

  The controller 3 collects and calculates vibration acceleration data acquired by the vibration measuring instrument 2 and outputs a calculation result. As shown in FIG. 1, the controller 3 includes a storage unit 11 for storing various programs and data, a control unit 12, an input unit 13 including a keyboard and a mouse, and a display including a printer and a monitor. It is mainly comprised by the means 14 and the clock part 15 which time-measures a date.

  The storage unit 11 includes, for example, an HDD (Hard Disk Drive), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The storage unit 11 includes a calculation program 11a for calculating a corrected dynamic load coefficient, a graph creation program 11b for creating a graph based on the calculation result, a vehicle basic data file 11c, a pavement data file 11d, a vibration acceleration data file 11e, Various programs and data files such as the result data file 11f are stored.

  The vehicle basic data file 11c includes the traveling speed of the vehicle V, the vehicle length, the mass, the axle weight (the load value at the measurement point when the vehicle is stationary), the suspension spring constant, the tire spring constant, the suspension damping constant, the tire damping constant, and the like. The basic value of the vehicle V is stored. These data are stored in the storage unit 11 by the input means 13.

  The pavement data file 11d contains the name, length, width, planned traffic volume (traffic volume classification), allowable deflection amount standard value, and the length of one segment of the pavement to be set arbitrarily. Is stored. These data are stored in the storage unit 11 by the input means 13. As shown in Fig. 3, the "allowable deflection reference value" is set in advance based on the planned traffic volume related to the pavement (New Standard Survey Results Report, Initial Survey (Survey Guidelines), Civil Engineering) Research Materials, No. 3157, April 1993). For example, when the planned traffic volume is 750 (vehicles / day / direction), the allowable deflection amount reference value is 600 μm.

  The vibration acceleration data file 11e stores vibration acceleration data measured by the vibration measuring instrument 2 in time series. The vibration acceleration data file 11e stores the measurement start date and time when the measurement is started, the measured vibration acceleration data, position data (latitude and longitude) acquired by GPS (Global Positioning System), and distance data. Are stored in the order of measurement in association with the measurement date / time data. By associating the vibration acceleration data, the position data, the distance data, and the measurement date / time data, the actual position of the pavement according to each calculated corrected dynamic load coefficient can be specified. The GPS function may be configured by installing a GPS driver and a GPS receiver in the controller 3. The number of vibration acceleration data measurements may be set as appropriate. In this embodiment, vibration acceleration data is acquired at 500 Hz (500 per second). As the distance data, for example, the travel distance from the measurement start position of the vehicle V can be measured by a vehicle speed pulse sensor or the like installed on the wheel of the vehicle.

  The result data file 11f stores a calculation result calculated by the control unit 12. In the result data file 11f, the name of the pavement when measured in the past, the basic value of the pavement, the basic value of the vehicle V traveled, the vibration acceleration data measured in the past, Past result data calculated based on vibration acceleration data is stored. The past result data is stored in association with the measured pavement and the year when the measurement was performed on the pavement. More specifically, in the past result data, the RMS, the corrected dynamic load coefficient, and the deflection amount measured by FWD, which will be described later, for each measured pavement section are stored for each measurement year.

  The control unit 12 is mainly configured by a CPU (Central Processing Unit) as an arithmetic device, and controls the entire operation of the pavement damage evaluation apparatus 1. The control unit 12 functions as the modified dynamic load coefficient calculation unit 12a when the calculation program 11a is read from the storage unit 11 and executed, and functions as the graph generation unit 12b when the graph generation program 11b is read from the storage unit 11 and executed.

  The modified dynamic load coefficient calculating means 12a first reads a plurality of vibration acceleration data for each section (for example, 20 m) of the pavement that has traveled, and substitutes it into the following equation 1 to calculate the root mean square (hereinafter, (Also referred to as “RMS”).

The corrected dynamic load coefficient calculating means 12a stores the calculated RMS in the result data file 11f for each section. For example, RMS corresponding to section 1 (less than 20 m from the measurement start position) is RMS ₁ , RMS corresponding to section 2 (less than 20 to 40 m) is RMS ₂ , RMS corresponding to section n is RMS _n. Remember.

Then, the corrected dynamic load coefficient calculating means 12a reads RMS _n from the result data file 11f and substitutes it into the following equation 2 to calculate the corrected dynamic load coefficient y for each section. Equation 2 is a regression equation Y calculated in advance by a dynamic load test described later. The calculation method of the regression equation Y will be described later.
y = 0.0284x + 1 (formula 2: regression equation Y)

Then, the corrected dynamic load coefficient calculation unit 12a stores the calculated corrected dynamic load coefficient y in the result data file 11f for each section. For example, modifying the dynamic load factor corresponding to Category 1 y _1, corrected dynamic load factor corresponding to the segment 2 y _2, modified dynamic load factor corresponding to the classification n which stores a y _n · · ·.

  The graph creating means 12b graphs the newly calculated corrected dynamic load coefficient, the past corrected dynamic load coefficient, the amount of deflection, and the conditions such as the service life of the pavement, and outputs the graph to the display means 14. To do. The graph creating unit 12b according to the present embodiment includes, for example, “graph 1 mode” and “graph 2 mode”.

  In the graph 1 mode, as shown in FIG. 5, the relationship between the service years and the corrected dynamic load coefficient is graphed by an instruction from the input means 13. That is, the graph creating unit 12b reads the corrected dynamic load coefficient y calculated this time from the result data file 11f of the storage unit 11, and reads past result data corresponding to the pavement measured this time from the result data file 11f. To reflect on the graph. Thereby, transition of the corrected dynamic load coefficient with respect to the serviced years of the measured pavement can be grasped.

  In the graph 2 mode, as shown in FIG. 6, the relationship between the corrected dynamic load coefficient and the deflection amount is graphed according to the command from the input means 13. The graph creation means 12b reads the past result data corresponding to the pavement measured this time from the result data file 11f of the storage unit 11 and reflects it in the graph to calculate the regression equation Z. The graph creating unit 12b reads the corrected dynamic load coefficient y calculated this time, substitutes it in the calculated regression equation Z, and reflects it in the graph. Further, the graph creating means 12b reads the reference value of the allowable deflection amount corresponding to the pavement measured from the pavement data file 11d and reflects it in the graph. Thereby, the future damage of the measured pavement can be predicted.

  The pavement damage evaluation apparatus 1 having such a configuration includes a measurement mode for measuring vertical vibrations of a traveling pavement and an analysis mode for analyzing the measurement result.

  Next, the damage evaluation method for a pavement according to this embodiment will be specifically described. As shown in FIG. 4, in the damage evaluation method for a pavement, a measurement step S1, a modified dynamic load coefficient calculation step S2, and a comparison step S3 are performed. This time, the case where the pavement of the 11th year from the start of service is measured is illustrated. The traveling distance of the pavement is 200 m, and the section is set by dividing the pavement at a pitch of 20 m. The reference value of the allowable deflection amount of the pavement to be measured is predetermined by the traffic volume classification, and is set to 600 μm in this embodiment.

  First, the operator installs the vibration measuring instrument 2 in the vicinity of the axle V1 of the vehicle V and inputs the basic value of the vehicle V and the basic value of the pavement through the input means 13 prior to the measurement step S1. The past result data relating to the pavement to be measured this time is stored in the storage unit 11 in advance. The past result data stores past result data measured in the first year, the eighth year, and the tenth year (a corrected dynamic load coefficient calculated in each year, a deflection amount obtained by FWD, and the like). It is preferable that the past measurement data includes at least two times of data. In this embodiment, although the result measured in 1,8,10 years is shown, the measurement data of other years may be sufficient.

  The operator travels on the pavement to be measured by the vehicle V and operates the input means 13 to input a measurement mode start command. The control unit 12 reads the date / time data measured by the clock unit and records it in the vibration acceleration data file 11e of the storage unit 11 as “measurement start date / time”.

  Then, the control unit 12 continuously samples the vibration acceleration data supplied from the vibration measuring instrument 2 according to a preset sampling rate, and records it in the vibration acceleration data file 11e of the storage unit 11 (measurement process). S1). When the vehicle V finishes traveling in the measurement section of the pavement, the operator operates the input means 13 to input a measurement mode end command. Thereby, the measurement mode ends.

  In the measurement mode described above, the control unit 12 causes the display unit 14 to display the output signal from the vibration measuring instrument 2 in real time. Thereby, the operator can confirm that the vibration measuring instrument 2 is operating normally during measurement.

  Next, the operator operates the input means 13 to input an analysis mode command. The control unit 12 executes the modified dynamic load coefficient calculation unit 12a and calculates the RMS for each section based on the above-described Expression 1. Then, the control unit 12 substitutes the calculated RMS into Equation 2 to calculate a corrected dynamic load coefficient for each section, and stores it in the result data file 11f in association with the measured pavement, service years, and section. At the same time, the calculation result is displayed on the display means 14 (modified dynamic load coefficient calculation step S2).

  Next, the operator operates the input means 13 to input a command for the graph 1 mode. The control part 12 performs the graph preparation means 12b, and graphs the relationship of the correction dynamic load coefficient with respect to service years, as shown in FIG. The graph creation means 12b reads the modified dynamic load coefficient y calculated this time (11th year) and the past result data corresponding to the currently measured pavement from the result data file 11f, and creates the created graph. And is displayed on the display means 14.

  Next, the operator operates the input means 13 to input a command for the graph 2 mode. The control unit 12 executes the graph creating unit 12b and graphs the relationship between the deflection amount and the corrected dynamic load coefficient as shown in FIG.

First, graph generator 12b is the first year was measured pavement, 8th years, reads the historical performance data for 10 years, the amount of deflection and correction dynamic load factor of each section in each year (D ₀ deflection Plot the amount). In FIG. 6, the past result data is represented by “□”. Then, the graph creating unit 12b derives the regression equation Z from the relationship between the corrected dynamic load coefficient related to the past result data and the deflection amount, and reflects it in the graph. In addition, the reference value of the allowable deflection amount (600 μm in this embodiment) is reflected in the graph. Here, the regression equation Z is expressed by the following equation 3, for example.
z = 900.68x-545.19 (formula 3: regression equation Z)

  Then, the graph creating means 12b substitutes the corrected dynamic load coefficient calculated by the current (11th year) measurement in Equation 3, and calculates the deflection amount derived from the current measurement result. In FIG. 6, the current deflection amount is represented by “x” (contrast step S3).

  As shown in FIG. 5, according to the graph displayed in the graph 1 mode, it can be seen that the value of the corrected dynamic load coefficient increases as the service life increases. The applicant found that the corrected dynamic load coefficient and the amount of flexure of the pavement are in a high correlation by a test using the vehicle V. That is, according to the graph of FIG. 5, it is possible to grasp the tendency of the amount of flexure of the pavement as the service life increases, that is, how the damage of the pavement increases. .

  Also, as shown in FIG. 6, according to the graph displayed in the graph 2 mode, as the service life increases, it is grasped at what ratio the corrected dynamic load coefficient approaches the reference value of the allowable deflection amount. it can. For example, if the amount of deflection calculated by this measurement exceeds 600 μm, it can be predicted that the pavement needs to be repaired.

  Further, the corrected dynamic load coefficient corresponding to the point where the calculated regression equation Z and the reference value of the allowable deflection amount intersect becomes the critical value. As an example, substituting the reference value of the allowable deflection amount of 600 μm into z = 900.68x−545.19, which is the regression equation Z, gives x = 1.27. If the modified dynamic load coefficient of the pavement is less than 1.27, it can be estimated that the pavement is generally sound.

  Thus, according to this embodiment, the measured damage to the pavement can be evaluated by obtaining the corrected dynamic load coefficient from the vertical acceleration of the vehicle that has traveled.

  In order to calculate the regression equation Z, it is necessary to acquire the past corrected dynamic load coefficient in the pavement to be measured and the past deflection amount using, for example, FWD, but if the regression equation Z can be calculated, If the data of the corrected dynamic load coefficient calculated in the measurement step S1 and the corrected dynamic load coefficient calculation step S2 is substituted into the regression equation Z, the damage can be evaluated. In other words, in the measurement year after the regression equation Z is calculated, it is not necessary to use a dedicated vehicle like FWD, and it is only necessary to install a vibration measuring instrument on a normal vehicle and run it. The cost of the apparatus can be reduced. Further, by using the corrected dynamic load coefficient, the evaluation can be performed regardless of the type of vehicle that travels.

  In order to calculate the regression equation Z, it is considered that there should be at least two years of past result data, but it goes without saying that more reliable results can be derived based on past results data of many years. .

  Although the embodiments of the present invention have been described above, design changes can be made as appropriate without departing from the spirit of the present invention. For example, in the present embodiment, two types of graphs, the graph 1 mode and the graph 2 mode, have been described, but other conditions may be combined to form a graph. For example, it is configured so that the relationship between one or two of FWD data, CBR (California Bearing Ratio), asphalt elastic modulus, service life, etc. acquired in advance and the corrected dynamic load coefficient is graphed and compared. Also good.

  By multiplying the modified dynamic load coefficient by the number of passing wheels and the passing axle weight, it is considered that the damage to the pavement caused by the vehicle passing through the pavement can be estimated in a manner close to actual.

  Next, the correlation between the road surface profile (road surface unevenness) and the structural damage of the pavement is verified according to the flow shown in FIG.

<Examination of calculation method of dynamic load: S11 in FIG. 7>
In order to grasp the damage of the pavement, it is necessary to accurately grasp the dynamic load applied to the pavement by the traveling vehicle. Therefore, a method has been considered in which the acceleration in the vertical direction of the axle (hereinafter also referred to as “unsprung”) is measured while the vehicle is running, and thereby the dynamic load is calculated. In order to verify its effectiveness, we conducted an on-site running test (dynamic load test) and compared the “dynamic load calculated from the unsprung vertical acceleration” with the “dynamic load calculated from the measured strain”. evaluated.

<Understanding of Influence of Road Surface Profile and Travel Speed on Dynamic Load: S12 in FIG. 7>
Since the road surface profile and travel speed can be considered as factors affecting the dynamic load, the theoretical calculation using the quarter car (hereinafter referred to as “QC”) model is used to determine the effect of these two factors on the dynamic load. I asked for.

<Relationship between road surface profile and pavement damage on actual road: S13 in FIG. 7>
Based on the above-mentioned theory, the road surface profile and the structural damage of the pavement are calculated using the “road surface profile and FWD data” in the actual road recorded in the LTPP (Long-Term Pavement Performance) published by the US Federal Road Authority. The relationship was examined.

First, the study (S11) of the dynamic load calculation method in FIG. 7 will be described in detail. Here, it was examined whether the dynamic load applied to the pavement by the traveling vehicle can be calculated from the unsprung vertical acceleration during traveling of the vehicle. In this examination, as shown in FIG. 8, a hump 21 having a known shape is provided on the test track on the premises, and the vertical acceleration under the spring when the vehicle V travels on the hump 21 is measured by the vibration measuring instrument 2 (see FIG. 2). More measured. A strain gauge 22 was installed on the back surface of the hump 21, and a dynamic load applied to the hump 21 by the traveling vehicle was determined based on the measured strain. Specifically, the dynamic strain was determined by introducing the measured strain when passing through the hump according to the relational expression (formula 4) between the load (P) and the strain (ε) of the hump 21 confirmed in advance in the laboratory test. The method of comparing the measured acceleration and dynamic load was examined.
P = 3.25 × 10 ⁶ ε (Formula 4)

  The running conditions of the dynamic load test were set to 9 to 11 conditions in the range of 5 to 40 km / h in the running speed, and the running speed was constant. The traveling vehicle was a regular car and a light vehicle truck.

  FIG. 9 is a graph showing the relationship between the vertical acceleration and the dynamic load in the dynamic load test. As shown in FIG. 9, the correlation coefficient between the vertical acceleration and the dynamic load was R = 0.88, and it was confirmed that there was a correlation between the vertical acceleration and the dynamic load. However, it was confirmed that the relationship between the vertical acceleration and the dynamic load differs depending on the traveling vehicle.

  In general, dynamic load is calculated as the product of acceleration and mass, so the axle load of the vehicle is regarded as one factor that determines the dynamic load. By removing this factor, measurement is possible regardless of the vehicle type. It was thought that the dynamic load was obtained from the vertical acceleration. Specifically, a value obtained by dividing the dynamic load by the axle load of the vehicle (the load value when the vehicle is stationary on the hump 21) is defined as “corrected dynamic load coefficient”. The relationship with vertical acceleration was obtained.

  FIG. 10 is a graph showing the relationship between the vertical acceleration and the corrected dynamic load coefficient in the dynamic load test. As shown in FIG. 10, the unsprung vertical acceleration and the corrected dynamic load coefficient do not depend on the vehicle type and are distributed on the regression equation Y (y = 0.0.284x + 1), and the correlation coefficient is R = 0.87, which is a large value. From this, it can be determined that it is effective to obtain the “corrected dynamic load coefficient” obtained by dividing the dynamic load obtained from the unsprung vertical acceleration by the axial load. That is, even in a traveling vehicle with an unknown axle load, it is possible to obtain the corrected dynamic load coefficient from the unsprung vertical acceleration during traveling, and it can be said that the influence of the dynamic load can be estimated. In this dynamic load test, an experiment was conducted using two types of vehicles to derive the regression equation Y, but it goes without saying that the regression equation Y varies as appropriate depending on the type of vehicle and the number of vehicles used in the test.

  Next, the grasp (S12) of the influence of the road surface profile and the traveling speed on the dynamic load in FIG. 7 will be described in detail. The vertical acceleration during vehicle travel is predicted to change depending on the road profile and the travel speed of the vehicle. Therefore, the change in vertical acceleration when the traveling speed was changed was obtained by calculation for a plurality of routes having different IRI (International Roughness Index), which is an index of the road surface profile. In addition, in order to verify whether the QC model used for the calculation can be applied in this study, first, verification regarding the adaptability of the QC model was performed.

  FIG. 11 is a schematic diagram showing a QC model. The QC model used here is a virtual vehicle obtained by extracting only one wheel of a two-shaft, four-wheeled passenger car that is also used for IRI calculation.

  The measured value of the vibration in the vertical direction when the vehicle traveled on the hump 21 was compared with the case of the QC model, and its adaptability was confirmed. In this verification, ISO (ISO 8608: Mechanical vibration-Road surface profiles-Reporting of measured data) proposes the measured value of unsprung vertical acceleration when running on hump 21 and the vertical acceleration obtained from QC model simulation. Comparison was made based on the power spectral density (hereinafter also referred to as “PSD”).

  FIG. 12 is a graph showing the relationship between the actual measurement value and the model calculation value PSD when traveling on humps. As shown in FIG. 12, it was found that the relationship between the measured value, the frequency of the QC model, and the PSD showed the same tendency. Based on this, it was considered possible to estimate the vibration acceleration in the vertical direction of the vehicle when traveling on various pavements using this QC model, and the vertical vibration of the traveling vehicle was calculated using the QC model. .

  The road surface profile used in this study is 10 lines with different IRI values (see FIG. 13). Moreover, the traveling speed of the QC model was set to seven conditions of 20, 30, 40, 50, 60, 70, and 80 km / h. Further, the load condition was set with a corrected dynamic load coefficient 1.0 of 49 kN.

  The corrected dynamic load coefficient was calculated by setting “Underspring vertical acceleration” when traveling on a pavement having different road surface profiles of IRI as the root mean square (hereinafter referred to as “RMS”) representing the intensity of vibration. The calculation formula of RMS is as described above (Formula 1).

    FIG. 14 is a graph showing the relationship between the road surface profile and the traveling speed. Considering FIG. 14, it can be seen that the corrected dynamic load coefficient increases as the traveling speed increases regardless of the IRI. Moreover, the corrected dynamic load coefficient tends to increase as the pavement body has a larger IRI. In addition, a route with a large change in the corrected dynamic load coefficient with respect to the traveling speed was observed. This is because the two natural frequencies (0.065 cycle / m and 0.42 cycle / m when running at 80 km / h) of the QC model match the frequency of the profile when running at a certain running speed. It is thought that resonance occurred. In order to confirm this, the PSD of the road surface profile was obtained for the route number 6 (IRI = 2.23) in which the corrected dynamic load coefficient was large at the traveling speed of 50 km / h.

    FIG. 15 is a graph showing the PSD of the road surface profile of the route number 6. As shown in FIG. 15, route number 6 indicates a large PSD at a frequency of 0.6 to 0.8 cycle / m (portion surrounded by a dotted line in FIG. 15). The natural frequency when the QC model travels at 50 km / h is 0.67 cycle / m (= 0.42 cycle / m × 80 km / h ÷ 50 km / h). From this, it can be considered that resonance has occurred and the corrected dynamic load coefficient has increased.

  As described above, in grasping the influence of the road surface profile and the traveling speed on the dynamic load (S12), the corrected dynamic load coefficient is larger as the paving body has a larger IRI, and further increases as the traveling speed increases. I understood. Therefore, on routes with the same traffic conditions such as the type of traffic vehicle and traffic volume, it is considered that a pavement with a larger IRI has a larger dynamic load and a greater damage to the pavement.

Next, the relationship (S13) between the road surface profile and the pavement damage on the actual road in FIG. 7 will be described in detail. Maximum amount of deflection measured road surface profile and FWD real path (hereinafter, referred to as "D ₀ deflection amount") is used to examine whether possible to estimate the structural damage of the pavement from the road surface profile.

Here, using the amount of change D ₀ deflection of the same portion as a structural damage pavements. This is because the purpose is not to specify the damaged portion of the pavement, but to estimate the degree of damage as a whole pavement from the road surface profile.

In this study, the corrected dynamic load coefficient is calculated from the known road surface profile data, the relationship between the deterioration over time and the change in the FWD D ₀ deflection amount is obtained, and there is a correlation between the road surface profile and the structural damage of the pavement. I evaluated it.

  The data used in the study is the results of a follow-up survey of a pavement (GPS-1) composed of an asphalt mixture layer and granular roadbed contained in LTPP Standard Data Release # 24 published by the Federal Highway Administration. . Among them, three lines (R105, R166, I-19) having different asphalt mixture layer thicknesses were selected.

  FIG. 16 is a table showing an outline of the study route. FIG. 17 is a diagram showing a survey outline of each route. As shown in FIGS. 16 and 17, the survey section has an extension of 152.4 m as one unit. The FWD is measured at a pitch of 7.6 m at OWP (outer wheel travel position). In this study, the calculation was performed with 22.8m (7.6 x 3) as one section, considering that the survey interval of pavement is generally about 20m in Japan. Based on this, the road profile data used in this study was also measured at OWP.

The corrected dynamic load coefficient of each line is obtained by calculating the RMS of the unsprung vertical acceleration when the QC model travels on the measurement pavement, and the RMS value is represented by the relational expression (y = 0.0284x + 1 (formula 2: Substituting into the regression equation Y)), the modified dynamic load coefficient was calculated. Since all three routes selected in this study were places where high speed travel was possible, the travel speed of the QC model was 80 km / h for all routes. In addition, the correction method shown in "Appendix L Asphalt pavement deflection temperature correction" proposed by the American Association of All-Traffic Road Transportation Administration (AASHTO) was used for the D ₀ deflection amount.

  In addition, in order to confirm the presence and location of structural failure, the FWD test results were used to obtain the asphalt elastic modulus and the roadbed CBR. However, the calculation method used was the deflection formula of “Let's use FWD” from the Road Maintenance Center.

FIG. 18 is a graph showing the relationship between the service years, the corrected dynamic load coefficient, and the D ₀ deflection amount. From FIG. 18, it can be confirmed that the aging change of the corrected dynamic load coefficient and the aging change amount of the D ₀ deflection amount show the same tendency in all three routes.

FIG. 19 is a graph showing the relationship between the corrected dynamic load coefficient and the D ₀ deflection amount. As shown in FIG. 19, it was confirmed that the correlation coefficient was R = 0.66 or more for all three routes.

  FIG. 20 is a graph showing the relationship between the asphalt elastic modulus and the roadbed CBR. As shown in FIG. 20, in R105 and R166, the elastic modulus of the asphalt layer was low. Moreover, in I-19, since the CBR of the roadbed is decreasing year by year, it is understood that the roadbed is damaged.

From the above, as generally said, the D ₀ deflection amount shows a smaller value as the asphalt elastic modulus and the CBR of the road bed increase. Therefore, the dynamic loads applied from the running vehicle, if the pavement is damaged, D ₀ deflection amount for asphalt modulus decreases layers damaged increases. From this, it is possible to estimate the damage of the pavement from the secular change of the D ₀ deflection amount. In addition, since it was confirmed that the D ₀ deflection amount and the corrected dynamic load coefficient have the same tendency and there is a correlation, the secular change of the D ₀ deflection amount can be confirmed by examining the change over time of the corrected dynamic load coefficient. The damage level of the pavement can be estimated in the same way as

  From the verification described above, it was found that the dynamic load of the traveling vehicle can be calculated by measuring the unsprung vertical acceleration. In addition, it is understood that the dynamic load of the traveling vehicle can be estimated regardless of the type of vehicle by using the “corrected dynamic load coefficient” obtained by dividing the dynamic load by the axial load. It was.

  It was also found that the dynamic load is affected by the road profile and the running speed of the vehicle. In addition, as a result of investigating the relationship between the modified dynamic load coefficient and the structural damage of the pavement using actual road measurement data, the secular change of the structural damage of the pavement correlates with the secular change of the corrected dynamic load coefficient. I found out that

  Therefore, by calculating the modified dynamic load coefficient devised as an evaluation index of dynamic load from the road surface profile and grasping its secular change, it is possible to predict structural damage of pavement that has been difficult until now It became. In addition, by multiplying the corrected dynamic load coefficient by the number of passing wheels and the passing axle weight, it is considered that the damage to the pavement caused by the passing traveling vehicle can be estimated in a form close to actual. From this, it is considered that there is a possibility that the life expectancy of the pavement considering the road surface profile can be relatively easily performed by using the modified dynamic load coefficient.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. As shown in FIG. 21, the pavement damage evaluation apparatus 1 </ b> A according to the second embodiment is different from the first embodiment in that the imaging unit 4 is installed in the vehicle and the captured image of the pavement is displayed on the display unit 14. Is different. In the second embodiment, the description will focus on the parts that are different from the first embodiment, and the description of the overlapping parts will be omitted.

  As shown in FIG. 21, in the pavement damage evaluation apparatus 1 </ b> A, an imaging unit 4 is installed in a vehicle V used for measurement, and an image processing unit 12 c is formed in the control unit 12. The imaging unit 4 is configured by a video camera, for example, and images the road surface of the pavement while the vehicle V is traveling. The imaging unit 4 is electrically connected to the control unit 12 via an image interface or the like. The imaging unit 4 starts imaging based on an operator's start command for the measurement mode, and ends imaging with the measurement mode end command. The captured image data obtained by the imaging means 4 is stored in the vibration acceleration data file 11e in association with vibration acceleration data, date / time data, position data obtained by the GPS function, distance data, and the like acquired from the vibration measuring instrument 2. .

  The image processing unit 12 c executes an “image processing mode” in which the captured image data acquired by the imaging unit 4 is displayed on the display unit 14 such as a monitor. More specifically, the image processing unit 12c reads each data such as captured image data, date / time data, position data, and distance data corresponding to arbitrary vibration acceleration data from the vibration acceleration data file 11e and displays it on the display unit 14. Display.

  As illustrated in FIG. 22, the image processing unit 12 c displays, for example, the captured image 31, the GPS image 32, and the acceleration graph 33 on the display unit 14. The captured image 31 is image data captured by the imaging unit 4. In the captured image 31, the surface of the pavement at an arbitrary point is displayed. For example, as shown in the portion surrounded by the symbol “E” in the captured image 31, the captured image 31 can grasp a crack formed in the pavement.

  The GPS image 32 is an image in which position data acquired by the GPS function is displayed on a map. For example, as indicated by a mark F, the GPS image 32 displays position data corresponding to arbitrary vibration acceleration data on a map.

  The acceleration graph 33 represents the relationship between measured vibration acceleration data and distance data. The acceleration graph 33 is created by the graph creation means 12b. The graph creation means 12b reads the vibration acceleration data and the distance data from the vibration acceleration data file 11e and creates an acceleration graph 33. The acceleration graph 33 may use date / time data (time data) instead of the distance data. The acceleration graph 33 may use a corrected dynamic load coefficient instead of the vibration acceleration data.

  Next, a specific operation of the pavement damage evaluation apparatus 1A will be described. Here, a different part from 1st embodiment is demonstrated in detail. In the measurement step S1, the operator operates the input means 13 to input a measurement mode start command. The control unit 12 reads the date / time data measured by the clock unit and records it in the vibration acceleration data file 11e of the storage unit 11 as “measurement start date / time”.

  Then, the control unit 12 continuously samples the vibration acceleration data supplied from the vibration measuring instrument 2 according to a preset sampling rate, and records it in the vibration acceleration data file 11e of the storage unit 11. Further, the control unit 12 stores the captured image data acquired by the imaging unit 4 in the vibration acceleration data file 11e in association with vibration acceleration data, date / time data, position data, distance data, and the like (measurement step S1). When the vehicle V finishes traveling in the measurement section of the pavement, the operator operates the input means 13 to input a measurement mode end command. Thereby, the measurement mode ends.

  Next, the operator operates the input unit 13 to input an image processing mode command. As shown in FIG. 22, the image processing unit 12 c reads the captured image 31, the GPS image 32, and the acceleration graph 33 from the vibration acceleration data file 11 e and displays them on the display unit 14. As an initial image of the captured image 31 and the GPS image 32 in the image processing mode, for example, an image at a measurement start position is displayed.

  As shown in FIG. 22, for example, the image processing unit 12c moves (executes) the cursor G by moving the cursor G to a position at a predetermined distance in the acceleration graph 33 (for example, a position 150 m from the measurement start position). Thus, the captured image 31 and the GPS image 32 corresponding to the position are displayed.

  In the pavement damage evaluation apparatus 1A described above, the imaging means 4 is provided, and the picked-up image 31 at a position corresponding to the measured vibration acceleration data can be seen. Therefore, damage to the pavement is visually evaluated. be able to.

  Further, in the present embodiment, by displaying the GPS image 32 obtained by the GPS function and the captured image 31 in association with each other, the situation of the pavement at a certain position can be visually confirmed, and the map on the place is displayed. The position can also be grasped. Thereby, it is possible to easily grasp the site of the pavement that is predicted to be damaged. In addition, in the conventional pavement inspection apparatus, the measurement cost is high because a dedicated vehicle has to be used. However, according to the present embodiment, any vehicle can be measured, so the measurement can be performed at low cost. Can do.

  In the second embodiment, design changes can be made as appropriate without departing from the spirit of the invention. For example, in the measurement mode described above, each data obtained from the vibration measuring instrument 2 and the imaging unit 4 may be displayed on the display unit 14 in real time as the captured image 31, the GPS image 32, and the acceleration graph 33. Thereby, the present condition of a pavement can be visually grasped while measuring.

DESCRIPTION OF SYMBOLS 1 Pavement damage evaluation apparatus 2 Vibration measuring instrument 3 Controller 4 Imaging means 11 Storage part 12 Control part 13 Input means 14 Display means 15 Clock part

Claims (3)

A pavement damage evaluation method for evaluating pavement damage,
A measurement step of running a vehicle with a vibration measuring instrument on the pavement and measuring vertical acceleration;
Substituting the measured vertical acceleration value into a regression equation calculated in advance by a dynamic load test, and calculating a corrected dynamic load coefficient,
The regression equation was obtained by dividing the dynamic load when a vehicle equipped with a vibration measuring instrument travels a predetermined position at a plurality of predetermined speeds by the axle load of the vehicle in the dynamic load test. A pavement damage evaluation method characterized by being obtained from a correlation between a plurality of corrected dynamic load coefficients and a plurality of vertical accelerations at the predetermined position obtained from the vibration measuring instrument.   2. The pavement according to claim 1, further comprising a comparison step of comparing a reference value of a predetermined allowable deflection amount in the pavement with the calculated corrected dynamic load coefficient. Damage evaluation method.   In the measurement step, an imaging unit is installed in the vehicle and travels on the pavement, and the captured image of the pavement acquired by the imaging unit and the measured vertical acceleration are associated with the display unit. The damage evaluation method for a pavement according to claim 1, wherein the damage is displayed.

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