CN104122022B - Vehicle axles dynamic load measuring instrument and assessment method - Google Patents

Abstract

The vehicle wheel axle dynamic load measuring instrument of the present invention comprises a plurality of lengthened screw rods and a rotating platform, and is characterized in that: it also includes an installation platform, an encoder and a fixed rod, and the installation platform is rotatably fixed on the bearing rod through a bearing; the encoder is fixed on It is installed on the platform, and the input shaft of the encoder is fixedly connected with the bearing rod through a shaft coupling, and an acceleration sensor is arranged on the rotating platform. The evaluation method of the present invention includes a). Weighing the static axle load; b). Loading vehicle instruments; c). Vehicle driving; d). Data collection; e). Static load conversion factor; g). Convert dynamic load to static load. The vehicle wheel shaft dynamic load measuring instrument and method of the present invention proposes a scientific theory and calculation method for converting static loads into dynamic loads, provides more practical theoretical guidance for road construction, and provides a basis for studying the destructive effects of vehicles on road surfaces using dynamic loads. laid the theoretical foundation.

Description

Vehicle Wheel Axle Dynamic Load Measuring Instrument and Evaluation Method

technical field

The invention relates to a vehicle wheel shaft dynamic load measuring instrument and evaluation method, more specifically, to a vehicle wheel shaft dynamic load measuring instrument and evaluation method for analyzing the vehicle speed and vertical acceleration.

Background technique

In my country's asphalt pavement design theory, the vehicle load is regarded as a static load or an approximate equivalent static load. After years of development, the static load mode pavement design theory has been relatively perfect, widely used, and accepted by engineering designers. This assumption is acceptable for static load mode pavement structure design when the vehicle speed is low and the vehicle is small. However, judging from the development trend of China's road traffic, my country's road traffic has entered the stage of heavy traffic, and the speed of vehicles is getting faster and faster. From the perspective of road function, it is an inevitable event for a vehicle to travel at a certain speed, while it is an accidental event for a vehicle to stand still. The actual vehicles are all heavy-duty high-speed vehicles, and the dynamic load applied to the road surface is a dynamic load with random changes in amplitude and action space. Due to the existence of dynamic loads, the difference between the static load mode and the actual force on the road surface during the driving process of the vehicle is relatively large, and the dynamic characteristics of the pavement structure are far from what the static characteristics can describe. These defects and differences, The existing design theories and methods cannot be solved fundamentally, and there are many damage phenomena on the pavement that cannot be explained by the static theory, such as fatigue cracking and loose materials. The damage and destruction of pavement structures are closely related to the motion loads generated by heavy vehicles. Clarifying the damage mechanism of asphalt pavement dynamic effects will promote the design, construction, maintenance and reconstruction of pavement structures and lay a solid foundation for the development of road science. .

At present, the method of obtaining vehicle load is mainly the weighing system, and there are currently static weighing and dynamic weighing systems. Static weighing requires that the vehicle must stop every time it is weighed, so that the traffic must be interrupted, and it cannot adapt to the weighing of large-capacity traffic loads; the dynamic weighing technology (Weigh-In-MotionWIM) provides a method that does not interrupt traffic. A technical means to automatically record and process vehicle weight, vehicle classification, vehicle speed and other data. A highway weighing system is a set of sensors and supporting instruments that can be used to measure the presence of a moving vehicle and its dynamic tire forces at a specific time at a specific location. In addition to the real axle load acting on the measurement sensor system during the measurement of dynamic weighing, there are many interference forces generated by many factors, such as vehicle speed, vehicle vibration, vehicle vibration caused by the road surface, tire characteristics, environmental factors, etc., the measurement The real axle load is often submerged in various disturbance forces, which will seriously affect the accuracy of dynamic weighing. The function of the dynamic weighing system is to help the highway traffic department understand the vehicle type composition, axle load spectrum and overweight degree of the current driving vehicles on the road, analyze the impact of overweight vehicles on road surface damage, and formulate corresponding management measures and regulations. To provide effective technical means for road operation departments to charge by vehicle weight. The weighing system can only measure at fixed points, and cannot detect the dynamic load imposed by the vehicle on the road in real time. The dynamic load of the vehicle is not only related to the load of the vehicle, but also related to the vehicle speed, road surface roughness and vehicle suspension parameters. The fixed-point weighing system cannot realize the real-time monitoring of the dynamic load of the vehicle, so it cannot reflect the time domain characteristics of the dynamic load of the vehicle. And the relationship between dynamic load characteristics and road surface roughness.

Contents of the invention

In order to overcome the disadvantages of the above-mentioned technical problems, the present invention provides a vehicle wheel axle dynamic load measuring instrument and evaluation method for analyzing the speed and vertical acceleration of the vehicle.

The vehicle wheel shaft dynamic load measuring instrument of the present invention includes a plurality of lengthening screws fixed on the vehicle hub and a rotating platform fixed on the lengthening screws, and bolt holes matching the lengthening screws are opened around the rotating platform; its special features In that: it also includes an installation platform, an encoder and a fixed rod, the center of the rotating platform is provided with a bolt hole matched with the bearing rod, the installation platform is rotatably fixed on the bearing rod through the bearing; the encoder is fixed on the installation On the platform, and the input shaft of the encoder is fixedly connected with the bearing rod through the coupling, the fixed rod is fixed with the rotating platform, and the upper end of the fixed rod is fixed with the non-rotating part of the car body during measurement; Acceleration sensor for vertical acceleration during vehicle running.

The extended screw rod is fixed on the wheel hub of the vehicle, and the rotating platform is fixed on the extended screw rod, so that the rotating platform can rotate with the rotation of the wheel. The installation platform is fixed on the bearing rod through bearings, and the installation platform is provided with a fixed rod fixed to the vehicle body, so that the rotating platform is in a static state relative to the vehicle body during the passing of the vehicle, so that An acceleration sensor is set on the installation platform to measure the vertical acceleration of the vehicle during driving. The input shaft of the encoder is fixed to the bearing rod through the shaft coupling, so that the input shaft of the encoder rotates with the rotation of the rotating platform, thereby realizing the measurement of the driving speed of the vehicle.

In the vehicle axle dynamic load measuring instrument of the present invention, the installation platform is in the shape of a U-shaped groove, and through holes are opened on both sides of the U-shaped groove installation platform, and the through holes on one side of the installation platform are matched with the bearings, and the other side The through hole matches the encoder.

In the vehicle wheel axle dynamic load measuring instrument of the present invention, the middle part of the elongated screw is provided with a boss or one end is provided with an elongated cap.

In the vehicle axle dynamic load measuring instrument of the present invention, the elongated screw rod is fixed to the rotating platform through the first nut, and the bearing rod is fixed to the rotating platform through the second nut.

The evaluation method of the vehicle wheel axle dynamic load measuring instrument of the present invention converts the vehicle dynamic load into a static load based on the principle of road surface damage equivalent, and its special feature is that it is realized by the following steps: a). Weighing the static axle load, Select a vehicle for a typical experiment and weigh the static vehicle axle load B). Load vehicle instrument, install the vehicle axle dynamic load measuring instrument as described in claim 1 on the wheel hub of the vehicle axle to be evaluated, to measure the speed and acceleration in the vehicle running process; c). Vehicle running , select a certain section of the actual road as the experimental section, and let the vehicle to be evaluated run on the experimental section; d). Data collection, in the process of vehicle driving, the instantaneous speed of the vehicle is continuously collected by using the encoder and the acceleration sensor in a fixed period and vertical vibration acceleration ;select speed The distance traveled by the vehicle within a period of time with a relatively stable size is taken as the effective experimental road section, and a total of group instantaneous speed and acceleration , ; Use the formula (1) to calculate the average speed in the effective experimental road section :

(1);

e). Calculate the dynamic load factor and its standard deviation, and calculate the vehicle dynamic load factor according to formula (2) :

(2)

in, is the acceleration of gravity;

Use the formula (3) to calculate the standard deviation of the vehicle dynamic load factor:

(3);

f). Calculate the static load conversion factor at the average speed Under the conditions, use the formula (4) to calculate the conversion factor of the dynamic load of the vehicle wheel axle into the static load required for asphalt pavement design :

(4)

in, is the dynamic load factor, is the distribution probability of the dynamic load coefficient, and its value is determined according to the following table:

Table 1 Dynamic load coefficient and its distribution probability

i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 dynamic load factor 3 σ _D 2.9σ _{D 2.7σD} 2.5 σ _{D 2.3σD 2.1σD} 1.9σ _{D 1.7σD} Distribution probability % 0.135 0.1205 0.2106 0.3537 0.5705 0.8847 1.318 1.8869

Continued Table 2 Dynamic load coefficient and its distribution probability

i=9 i=10 i=11 i=12 i=13 i=14 i=15 i=16 dynamic load factor 3 σ _D 2.9σ _{D 2.7σD} 2.5 σ _{D 2.3σD 2.1σD} 1.9σ _{D 1.7σD} Distribution probability % 0.135 0.1205 0.2106 0.3537 0.5705 0.8847 1.318 1.8869

g). Convert the dynamic load into static load, according to the equivalent principle of dynamic and static load damage to the road surface, when the vehicle speed is Under the condition of , according to the formula (5), the dynamic load is transformed into the static load required for pavement design:

(5)

By using the load values converted from dynamic loads to static loads for evaluation, a more practical theoretical guidance is put forward for pavement construction.

The evaluation method of the vehicle axle dynamic load measuring instrument of the present invention, the speed described in step d) is to expressway and first-class highway: =60km/h, 80km/h, 100km/h, 120km/h; for second, third and fourth grade roads: =20km/h, 40km/h, 60km/h, 80km/h.

The beneficial effect of the present invention is: the vehicle wheel axle dynamic load measuring instrument of the present invention, the rotating platform is fixed on the vehicle wheel hub through the lengthened screw rod, the bearing rod is fixed at the center of the rotating platform, and the encoder is fixed to the bearing rod through the shaft coupling , using the encoder to realize the measurement of the vehicle speed; the installation platform is fixed on the bearing rod through the bearing, and the installation platform is provided with a fixed rod fixed with the vehicle body, so that the installation platform does not rotate with the rotation of the rotating platform, which is convenient for fixing The acceleration sensor measures the acceleration in the vertical direction when the vehicle is passing by. According to the measured vehicle speed, vertical acceleration and vehicle weight, the wheel axle dynamic load of the vehicle can be analyzed to provide a reliable theoretical basis for road construction and maintenance.

The evaluation method of the vehicle axle dynamic load measuring instrument of the present invention converts the vehicle dynamic load into a static load based on the principle of road surface damage equivalent, and first obtains the average speed of a typical vehicle in an effective experimental road section , dynamic load coefficient and the standard deviation of the dynamic load coefficient, the conversion coefficient of static load to dynamic load is calculated by using the dynamic load coefficient and its distribution probability , and finally the static load is calculated by the conversion coefficient, and the load value after the dynamic load is converted into the static load is used for evaluation. The evaluation method of the vehicle wheel shaft dynamic load measuring instrument of the present invention proposes a scientific theory and calculation method for converting static loads into dynamic loads, and provides more practical theoretical guidance for road construction, and is used to study the destructiveness of vehicles on road surfaces using dynamic loads. Influence lays the theoretical foundation.

Description of drawings

Fig. 1 is the structural representation of vehicle axle dynamic load measuring instrument and evaluation method of the present invention;

Fig. 2 is the exploded view of vehicle axle dynamic load measuring instrument and evaluation method of the present invention;

Fig. 3 is a structural schematic diagram of a vehicle axle dynamic load measuring instrument and an evaluation method applied to a truck;

Fig. 4 is the structural representation of rotating platform among the present invention;

Fig. 5 is a structural schematic diagram of the installation platform in the present invention.

In the figure: 1 extended screw rod, 2 bearing rod, 3 rotating platform, 4 first nut, 5 second nut, 6 bearing, 7 installation platform, 8 coupling, 9 fixed rod, 10 encoder, 11 boss, 12 Long nut, 13 through holes.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1 and Fig. 2, the structure diagram and exploded view of the vehicle axle dynamic load measuring instrument and evaluation method of the present invention are provided, which include an extended screw rod 1, a bearing rod 2, a rotating platform 3, an installation platform 7, a joint Shaft device 8, fixed rod 9, encoder 10; the number of lengthening screw rod 1 shown is over 10, one end of lengthening screw rod 1 is fixed with the wheel hub of the vehicle, and the other end is fixed with the rotating platform 3, as shown in Figure 4 , shows a schematic view of the structure of the rotating platform, the rotating platform 3 is shown around the opening with a through hole 13 to match the lengthening screw 1 . Through the cooperation between the first nut 4 and the lengthening screw 1 , the rotating platform 3 can be firmly fixed on the lengthening screw 1 . The central position of the rotating platform 3 is provided with a through hole matched with the bearing rod 2, and the bearing rod 2 is fixed at the central position of the rotating platform 3 by the second nut 5, so that in the process of rotating the rotating platform 3, the bearing rod 2 Can rotate with it.

The shown installation platform 7 is a U-shaped groove shape, and the two side plates of the U-shaped groove-shaped installation platform 7 are provided with passages 13. As shown in Figure 5, the structural representation of the installation platform is provided. One side of the installation platform 7 A bearing 6 matched with the bearing rod 2 is arranged in the through hole of the through hole, and the encoder 10 is fixed at the through hole on the other side of the installation platform 7 . The input shaft of the encoder 10 passes through the through hole and is fixed to the bearing rod 2 through the shaft coupling 8. In this way, when the rotating platform 3 rotates with the vehicle, the bearing rod 2 will drive the input shaft of the encoder 10 to rotate together. Realize the measurement of vehicle speed.

The shown fixed rod 9 is fixed with the installation platform 7, and in use, the fixed rod 9 is fixed with the non-rotating part of the vehicle to ensure that the installation platform 7 is in a static state relative to the vehicle body. The shown installation platform 7 is set in a horizontal state, and the installation platform is fixed with an acceleration sensor for measuring the acceleration in the vertical direction during the running of the vehicle. The acceleration sensor can use a three-axis acceleration sensor to measure the acceleration in three directions. The acceleration value in the vertical direction of the vehicle is sufficient. On the basis of obtaining the speed of the vehicle and the acceleration in the vertical direction, combined with the weight of the vehicle, the dynamic load of the wheel axle of the vehicle can be calculated and analyzed, and then the force state of the road surface can be analyzed, which can provide a basis for the construction and maintenance of the road surface. And maintenance to provide scientific reference.

Bosses 11 are provided at the middle of the lengthening screw 1 in Fig. 1 and Fig. 2 to realize the limiting effect on the rotating platform 3. The lengthening screw 1 of this structure is suitable for the measurement of the dynamic load of the wheel axle of a car. In FIG. 3 , a long nut 12 is fixed at one end of the lengthening screw 1 shown. The lengthening screw 1 of this structure is used to cooperate with the wheel hub of the truck to realize the measurement of the dynamic load of the wheel axle of the truck.

The acceleration sensor can use a three-axis acceleration sensor, such as a sensor model GY-521, its functions and characteristics are: power supply: 3-5v (internal low dropout voltage regulator); communication method: standard IIC communication protocol; chip built-in 16bitAD Converter, 16-bit data output; power supply: 3-5v. The encoder 10 can be an incremental rotary encoder of type 400P/R, which can generate counting pulse signals with recognizable directions through the rotating grating disk and optocoupler; performance: 400 pulses per revolution; working voltage: 5-24V, maximum mechanical The speed is 1000 rpm.

The installation method of the vehicle axle dynamic load measuring instrument and evaluation method of the present invention is as follows (taking the detection of a car as an example):

(1) Replace the fastening screw in the wheel hub of the car with the extended screw 1, thereby lengthening the fastening screw of the vehicle tire;

(2) Install the rotating platform 3 on the extension screw 1, and fasten it with the first nut 4;

(3) Install the bearing rod 2 on the rotating platform and fasten it with the second nut 5;

(5) Install the bearing 6 on the through hole on one side of the installation platform 7;

(6) Install the installation platform 7 on which the upper bearing 6 is installed on the bearing rod 2;

(7) Install the encoder 10 on the other end of the installation platform 7 and fasten it with screws;

(8) Install one end of the coupling 8 on the bearing rod 2, and install the other end on the input shaft of the encoder 10 to realize the synchronous rotation of the bearing rod 2 and the encoder 10, so that the wheel rotation speed can be measured;

(9) On the installation platform 7, install the acceleration sensor and fasten it with screws; in order to prevent the short circuit between the sensor and the installation platform 7, it is necessary to apply a layer of epoxy resin on the installation platform 7;

(10) Install the fixed rod 9 on the loading platform 7 and fasten it with a nut;

(11) Connect the fixed rod 9 to the carriage to meet the requirements that the fixed rod can slide up and down, but cannot move in translation, so as to achieve the purpose of vertical free vibration of the acceleration sensor installation platform but not rotation;

(12) Connect the acceleration sensor and the encoder 10 data line with the computer with calculation function;

(13) The acceleration signal is converted into vibration acceleration, and then converted into axle vibration load, and the encoder signal is converted into vehicle speed signal, so that the real-time correlation measurement of vehicle speed and axle dynamic load can be realized.

The evaluation method of the vehicle axle dynamic load measuring instrument of the present invention converts the dynamic load of the vehicle into a static load based on the principle of road surface damage equivalent, and realizes through the following steps:

a). Weigh the static axle load, select a typical experimental vehicle, and weigh the static vehicle axle load ;

b). Loading the vehicle instrument, installing the vehicle wheel axle dynamic load measuring instrument as described in claim 1 on the wheel hub of the vehicle axle to be evaluated, to measure the speed and acceleration during the running of the vehicle;

In this step, the stated speeds for expressways and first-class roads: =60km/h, 80km/h, 100km/h, 120km/h; for second, third and fourth grade roads: =20km/h, 40km/h, 60km/h, 80km/h.

c). When the vehicle is running, select a certain section of the actual road as the experimental road section, and let the vehicle to be evaluated run on the experimental road section;

d). Data acquisition. During the driving process of the vehicle, the encoder and acceleration sensor are used in a fixed period to continuously collect the instantaneous speed of the vehicle and vertical vibration acceleration ;

select speed The distance traveled by the vehicle within a period of time with a relatively stable size is taken as the effective experimental road section, and a total of group instantaneous speed and acceleration , ; Use the formula (1) to calculate the average speed in the effective experimental road section :

(1);

e). Calculate the dynamic load factor and its standard deviation, and calculate the vehicle dynamic load factor according to formula (2) :

(2)

in, is the acceleration of gravity;

Use the formula (3) to calculate the standard deviation of the vehicle dynamic load factor:

(3);

f). Calculate the static load conversion factor at the average speed Under the conditions, use the formula (4) to calculate the conversion factor of the dynamic load of the vehicle wheel axle into the static load required for asphalt pavement design :

(4)

in, is the dynamic load factor, is the distribution probability of the dynamic load coefficient, and its value is determined according to the following table:

Table 1 Dynamic load coefficient and its distribution probability

i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 dynamic load factor 3 σ _D 2.9σ _{D 2.7σD} 2.5 σ _{D 2.3σD 2.1σD} 1.9σ _{D 1.7σD} Distribution probability % 0.135 0.1205 0.2106 0.3537 0.5705 0.8847 1.318 1.8869

Continued Table 2 Dynamic load coefficient and its distribution probability

i=9 i=10 i=11 i=12 i=13 i=14 i=15 i=16 dynamic load factor 3 σ _D 2.9σ _{D 2.7σD} 2.5 σ _{D 2.3σD 2.1σD} 1.9σ _{D 1.7σD} Distribution probability % 0.135 0.1205 0.2106 0.3537 0.5705 0.8847 1.318 1.8869

g). Convert the dynamic load into static load, according to the equivalent principle of dynamic and static load damage to the road surface, when the vehicle speed is Under the condition of , according to the formula (5), the dynamic load is transformed into the static load required for pavement design:

(5)

By using the load values converted from dynamic loads to static loads for evaluation, a more practical theoretical guidance is put forward for pavement construction.

The evaluation method of the vehicle axle dynamic load measuring instrument of the present invention converts the dynamic load of the vehicle into a static load based on the principle of pavement damage equivalence, and proposes a scientific theory and calculation method for converting static load into dynamic load, which is more suitable for road construction. The practical theoretical guidance has laid a theoretical foundation for the study of the destructive impact of vehicles on the road surface by using dynamic loads.

Claims (6)

1. A vehicle wheel shaft dynamic load measuring instrument, comprising a plurality of lengthened screw rods (1) fixed on the vehicle hub and a rotating platform (3) fixed on the lengthened screw rod, the surrounding of the rotating platform is equipped with a Bolt holes; it is characterized in that: it also includes a mounting platform (7), an encoder (10) and a fixed rod (9), and the center position of the rotating platform is provided with a bolt hole matched with the bearing rod (2), and the installation The platform is rotatably fixed on the bearing rod through the bearing (6); the encoder is fixed on the installation platform, and the input shaft of the encoder is fixedly connected with the bearing rod through the coupling (8), and the fixed rod is fixed to the installation platform. During the measurement, the upper end of the fixed rod is fixed to the non-rotating part of the car body; the rotating platform is provided with an acceleration sensor for measuring the acceleration in the vertical direction during the running of the vehicle. 2. The vehicle wheel axle dynamic load measuring instrument according to claim 1, characterized in that: the installation platform (7) is in the shape of a U-shaped groove, and both sides of the U-shaped groove installation platform are provided with through holes (13) , the through hole on one side of the mounting platform matches the bearing (6), and the through hole on the other side matches the encoder (10). 3. The vehicle axle dynamic load measuring instrument according to claim 1 or 2, characterized in that: the middle part of the elongated screw (1) is provided with a boss (11) or one end is provided with an elongated cap (12). 4. The vehicle wheel axle dynamic load measuring instrument according to claim 1 or 2, characterized in that: the elongated screw rod (1) is fixed to the rotating platform (3) through the first nut (4), and the bearing rod (2) It is fixed with the rotating platform through the second nut (5). 5. A method of evaluation based on the vehicle wheel axle dynamic load measuring instrument according to claim 1, the vehicle dynamic load is converted into a static load based on the road surface damage equivalent, and it is characterized in that it is realized by the following steps: a). Weigh the static axle load, select a typical experimental vehicle, and weigh the static vehicle axle load G _S ; b). Loading the vehicle instrument, installing the vehicle wheel axle dynamic load measuring instrument as described in claim 1 on the wheel hub of the vehicle axle to be evaluated, to measure the speed and acceleration during the running of the vehicle; c). When the vehicle is running, select a certain section of the actual road as the experimental road section, and let the vehicle to be evaluated run on the experimental road section; d). Data collection. During the driving process of the vehicle, the encoder and the acceleration sensor are used in a fixed period to continuously collect the instantaneous velocity v and the vertical vibration acceleration a of the vehicle; Select the distance traveled by the vehicle within a period of time when the speed v is relatively stable as the effective experimental road section, and there are n groups of instantaneous speed v _j and acceleration a _j in the effective experimental road section, j=0,1,2,...,n; Use the formula (1) to calculate the average speed V in the effective experimental road section: $\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ e). Calculate the dynamic load coefficient and its standard deviation, and calculate the dynamic load coefficient D _i of the vehicle according to the formula (2): ${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ Among them, g is the acceleration due to gravity; Use the formula (3) to calculate the standard deviation of the vehicle dynamic load factor: ${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; =</span>\sqrt{\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ f). Calculate the static load conversion coefficient. Under the condition of average speed V, use the formula (4) to calculate the conversion coefficient k of the static load required for the asphalt pavement design from the dynamic load of the vehicle wheel axle: $\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 16</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 4.35</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 16</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 4.35</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$ Among them, a _i is the dynamic load coefficient, p _i is the distribution probability of the dynamic load coefficient, and its value is taken according to the following table: Table 1 Dynamic load coefficient and its distribution probability Continued Table 2 Dynamic load coefficient and its distribution probability g). Convert dynamic loads into static loads. According to the equivalent principle of dynamic and static loads on road surface damage, under the condition of vehicle speed V, convert dynamic loads into static loads required for road surface design according to formula (5): G _D =k×Gs(5) By using the load values converted from dynamic loads to static loads for evaluation, a more practical theoretical guidance is put forward for pavement construction. 6. The evaluation method of vehicle axle dynamic load measuring instrument according to claim 5, characterized in that: the speed described in step d) is to expressway and first-class road: v=60km/h or 80km/h or 100km /h or 120km/h; for second, third and fourth grade roads: v=20km/h or 40km/h or 60km/h or 80km/h.