JPH04125436A - Method for measuring reaction force on road surface - Google Patents

Abstract

PURPOSE:To reduce a cost and save power by measuring reaction force on a road surface which a mass body is applied from difference in external force respectively functioning to the mass body between a state with the body on the road surface and a state with the body floating. CONSTITUTION:When vertical vibratory force F is applied to a mass body 2 on a road surface 6, the body is subjected to external force R(t) from the road surface 6, a frame 1, etc. where R(t)=Malpha0-F. When the vibratory force F is applied when the mass body 2 floats from the road surface 6, the body is subjected to external force R1(t) from the frame 1, etc. where R1(t)=Malpha1-F. By subtracting the external force R1(t) from the external force R(t), reaction force R0(+) can be obtained. External force functioning to the mass body 2 can be obtained from a product of vertical acceleration and a mass M with the vibratory force F subtracted therefrom. Thus indirect measurement of reac tion force is possible while a cost is reduced and power is saved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to a vibrating roller, a vibrating compactor, etc.
The present invention relates to a method of measuring the reaction force that a mass body receives from a road surface when using a device that compacts a road surface by vertically vibrating the mass body.

[Conventional technology]

A compaction device such as a vibrating roller or a vibratory compactor is a device that applies an excitation force in the vertical direction to a mass body such as a roller or a plate, and compacts a road surface using the impact force generated by the vertical movement of the mass body at that time.

Here, as the compaction of the road surface progresses, the amount of depression of the road surface due to the vertical movement of the mass body decreases, so the reaction force exerted by the road surface on the mass body increases in proportion to the degree of compaction of the road surface.

Therefore, by measuring the reaction force exerted by the road surface on a mass body, it is possible to quantitatively understand the degree of compaction of the road surface, thereby preventing problems such as insufficient compaction or repeated unnecessary construction. It disappears.

One conventional method for measuring the reaction force that a mass body receives from the road surface is to embed an earth pressure gauge in the road surface and directly measure it.

[Problem to be solved by the invention]

However, with the conventional method of directly measuring the reaction force received from the road surface using soil pressure gauges embedded in the road surface, a large number of soil pressure gauges are required to measure the reaction force over a wide area during construction work. However, this method was impracticable in practice due to the enormous cost and labor involved.

This invention was made by focusing on such unresolved problems with the conventional technology, and it is possible to measure the reaction force that the mass body of a compaction device receives from the road surface without expending a large amount of cost and effort. The purpose is to provide a method that can be used.

[Means for Solving the Problems] In order to achieve the above object, the invention as set forth in claim (1) provides a method for causing the mass body to compact the road surface by applying an excitation force in the vertical direction to the mass body. A method of measuring the reaction force received from the mass body when the mass body is placed on the road surface from an external force that acts on the mass body when the vibration force is applied to the mass body when the mass body is placed on the road surface. The reaction force that the mass body receives from the road surface is measured by subtracting the external force that acts on the mass body when the vibration force is applied to the body.

Further, the invention according to claim (2) is a method for measuring a reaction force that a mass body receives from a road surface when compacting a road surface by applying an excitation force in the vertical direction to a mass body, the method comprising: Measure the vertical acceleration of the mass body when the excitation force is applied to the mass body in a state where the mass body is placed at Then, determine the external force that acts on the mass body during vibration on the road surface, measure the vertical acceleration of the mass body when the vibration force is applied to the mass body while floating from the road surface, and calculate the vertical acceleration and The excitation force is subtracted from the value multiplied by the mass of the mass body to determine the external force that acts on the mass body during air vibration, and the external force that acts on the mass body during vibration on the road surface is calculated from the The reaction force that the mass body receives from the road surface is measured by subtracting the external force that acts on the mass body during aerial vibration.

[Effect]

When a vertical excitation force F is applied to the mass body placed on the road surface, the mass body receives a predetermined acceleration α while receiving an external force R(t) from the road surface side, the frame side of the compaction device, etc. . Since it moves up and down, if the mass of the mass body is M, the equation of motion is as shown in equation (1) below.

Mα. -F + R(t)...
...(1) Therefore, the external force R(t) acting on the mass body is
It can be expressed as the following equation (2).

R(t) −Mα. -F...
(2) On the other hand, when a vertical excitation force F is applied to the mass body while it is suspended from the road surface, the mass body receives an external force R, (t) from the frame side, etc., and receives an acceleration α1. Since it moves up and down, the equation of motion in this case is as shown in equation (3) below.

Mα+ =F+R+(t)...
-(3) Therefore, the external force R+(t) acting on the mass body in this state can be expressed as in the following equation (4).

R+ (t) = Mα, -F...
...(4) Then, the external force R(t
) includes the external force acting from the road surface, that is, the reaction force R6 (1) that the road surface gives to the mass body, but the external force R + (t) shown in equation (4) above includes the reaction force Ro (t). is not included, so if external force R+(t) is subtracted from external force R(t), reaction force R8(1) remains.

Therefore, as in the invention described in claim (1), from the external force that acts on the mass body when an excitation force is applied while it is placed on a road surface, the mass body when an excitation force is applied while it is suspended from the road surface. By subtracting the external force acting on the body, the reaction force that the mass body receives from the road surface can be found.

Furthermore, as shown in equations (2) and (4) above, the external force acting on the mass body is the vertical acceleration α of the mass body. , can be obtained by subtracting the excitation force F from the product of α1 and the mass M.

Therefore, if the vertical acceleration of the mass body is measured as in the invention described in claim (2), the excitation force and the mass of the mass body are known, so the external force acting on the mass body can be calculated by calculation. ,
As a result, the reaction force that the mass body receives from the road surface is measured.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram of a vibrating roller, which is one of the compaction devices. In this roll 2, a vibrator 3 that applies an excitation force to the roll 2 is provided integrally with the roll 2 (but independently in the rotational direction).

The exciter 3 has two rotating shafts 3a and 3b that are horizontal to the frame 1 and parallel to each other.
and 3b are connected to an unillustrated rotary drive device constituted by an engine or the like so as to rotate in opposite directions and at the same speed.

Weights 3c and 3d eccentric from the axis are fixed to each of the rotating shafts 3a and 3b, and these weights 3c and 3d have the same mass and move as the rotating shafts 3a and 3b rotate. The vertical components of the generated centrifugal force are fixed in the same direction, and the horizontal components are fixed in opposite directions.

Therefore, when the rotating shafts 3a and 3b rotate, centrifugal force is generated on the rotating shafts 3a and 3b by the weights 3c and 3d, but the horizontal component of the centrifugal force is
and 3b, so that an excitation force F in the vertical direction is generated in the exciter 3.

The exciter 3 also includes an acceleration sensor 4 that measures the vertical acceleration generated in the exciter 3, and a center of gravity of the weight 3d that is located on the exciter 3.
A pulse sensor 5 that generates a pulse when facing outward in the horizontal direction is provided. In addition, in FIG. 1, 6 is a road surface.

FIG. 2 is a diagram modeled on the vibrating roller shown in FIG. 1, in which the spring constant between the frame 1 and the roll 2 is
1 decay constant between frame 1 and roll 2 is CI, roll 2
and the spring constant between the road surface 6 is 0, the damping constant between the roll 2 and the road surface 6 is 00, the mass of the frame 1 (spring mass) is M8, the mass of the roll 2 (spring mass) is M, the mass of the roll 2 is Let the vertical displacement be X.

As mentioned above, the excitation force F is generated by the two rotating shafts 3.
1. Because it is the resultant force of the vertical component of the centrifugal force generated when rotating a and 3b. The rotational angular velocity of the rotating shafts 3a and 3b is ω, and the magnitude of the centrifugal force generated on each of the rotating shafts 3a and 3b is F. /2, the following equation (5) is obtained.

F −F 0CO3(L) t −
...(5) Therefore, when the excitation force F is applied to the roll 2 placed on the road surface 6 (hereinafter referred to as vibration on the road surface), the equation of motion is as shown in equation (6) below. become. however,
Since the vibrations generated in the frame 1 are minute compared to the vibrations on the roll 2 side, it is assumed here that the frame 1 is stationary.

MM + c, large + x + co large + kox = FoCO3ω
t...(6) On the other hand, when the roll 2 is suspended from the road surface 6 and the excitation force F is applied (hereinafter referred to as air vibration), the equation of motion is:
It will look like (7) 2 below.

MX+c, i+ +x=FoCO3ωt...(
7) And among the elements included in (6) 2 above, road surface 6
The external force applied to the roll 2 from the side, that is, the reaction force R8 (1) applied to the roll 2 by the road surface 6 has a spring constant k.

and the part related to the damping constant 00, so the following (8)
It can be expressed as the formula.

Ro(t)-〇. i tenk. X ・Old・(8
) Therefore, in order to find the reaction force Re(t), the displacement χ.

High speed, acceleration i, mass M, spring constant +, damping constant 01, and excitation force F. If COSωt is known, the acceleration factor can be measured by the acceleration sensor 4, the mass M of the roll 2, and the excitation force F. COSω
t is determined from the specification values of the vibrating roller. And other factors, external force R+(
t)=c, x+, and x is obtained from the following equation (9), which is a modification of the above equation (7).

R+(t)=FoCOSωt M! ...
(9) Furthermore, the external force R (t) = cli + kl It will be done.

R(t) = F. COS ω t −M wise ・・・・・・0 mouth) And,
If we pay attention to the external force R, (t), R(t) and the reaction force RO(t), it can be seen that the reaction force Ro(t) is obtained by the following equation 01).

Ro(t)=R(t) R+(t) ・
...(11) However, the excitation force F. Since COSωt is a sine wave that vibrates at a predetermined frequency, the excitation force F. C
If the phase difference between OSωt and the acceleration value is not known, the above equations (9) and 0(1) cannot be calculated.

Therefore, the phase difference is determined based on the pulse that the pulse sensor 5 emits every rotation of the rotating shaft 3b and the acceleration that the acceleration sensor 4 measures.

FIG. 3 is a graph in which the acceleration during air vibration and the output pulse of the pulse sensor 4 are plotted on the same time axis. However, the rotational speed of the engine to which the rotating shafts 3a and 3b of the exciter 3 were connected was 1.60 Or pm, and the vibration frequency of the exciter 3 was 2112 rpm.

That is, the output pulse and the excitation force F. Since the period is the same as that of CO8ω, the phase difference between this output pulse and the acceleration source is the excitation force F. This is the phase difference between CO8ωt and the acceleration factor.

Further, FIG. 4 is a graph in which the acceleration rate during vibration on the road surface and the output pulse of the pulse sensor 4 are plotted on the same time axis. In this case as well, the rotational speed of the engine to which the rotating shafts 3a and 3b of the vibration generator 'a3 were connected was 1600 rpm, but the vibration frequency of the vibration generator 3 was 2016 rpm.

The reason why the vibration frequency is different when vibrating in the air and when vibrating on the road surface is that the required horsepower is different when vibrating in the air and when vibrating on the road surface.Since it is driven by hydraulic pressure, the vibration frequency can be accurately controlled by the engine speed. This is because it is difficult to do so, but an error of this degree does not actually pose a problem.

From the results shown in FIG. 3, the force Mid generated on the roll 2 during aerial vibration is the excitation force F of the roll 2, as shown in the upper part of FIG. CO8ωt is shown in the middle row of Figure 5, and the external force R+ (t) which is the difference between these (see equation (9) above)
is as shown in the lower part of FIG.

Here, as can be seen from FIG. 5, the external force R+(t) lags behind the force M and the excitation force F0CO3ωt by about π/2. This is because the damping force between the frame 1 and the roll 2 has a large influence.

Furthermore, from the results shown in FIG. 4, the force MW generated on the roll 2 during vibration on the road surface is the excitation force F of the roll 2, as shown in the upper part of FIG. COSωt is shown in the middle part of Figure 6, and the external force R(t), which is the difference between these (see formula 00 above), is
The result will be as shown in the lower part of the figure.

In addition, the excitation force F during air vibration. COSωt (see the middle row of Figure 5) and the excitation force F during vibration on the road surface. COSωt (6th
(See the middle row of the figure) is slightly different because, as mentioned above, the vibration frequency is slightly different due to the difference in experimental conditions.

If the external forces R+(t) and R(t) are drawn in one graph, it will be as shown in the upper part of FIG. 7, and if the difference between these is calculated, it will be as shown in the lower part of FIG. This is the reaction force R8(1) that the roll 2 receives from the road surface 6.

However, the static molding amount M+g+Mg (g is gravitational acceleration) of the frame 1 and roll 2 is added to the final reaction force Ro(t).

In this way, in this embodiment, the reaction force Ro(t) that the roll 2 receives from the road surface 6 can be determined indirectly based on the output of the acceleration sensor 4, so that Since a large number of soil pressure gauges and the like are not required, it can be carried out without expending a great deal of cost and labor.

If the reaction force Ro(t) is measured, it is possible to quantitatively understand the compaction state of the road surface 6.
Problems such as insufficient compaction or repeated unnecessary construction work after sufficient compaction are eliminated.

In the above embodiment, the present invention is applied to a vibrating roller having the roll 2 as a mass body, but the present invention is not limited to this, and the present invention can also be applied to a vibrating compactor in which the mass body is in the form of a flat plate. The same applies.

〔Effect of the invention〕

As explained above, according to the present invention, there is an effect that the reaction force that the mass body of the compaction device receives from the road surface can be determined indirectly without spending a great deal of cost or effort. The compacted state of the road surface can be easily and quantitatively understood during construction work.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the vibrating roller, Fig. 2 is a model showing the configuration of Fig. 1, Fig. 3 is a graph showing output pulses and acceleration during vibration in the air, and Fig. 4 is a graph showing the vibration roller on the road surface. A graph showing the output pulse and acceleration during vibration, Fig. 5 is a graph showing the force acting on the roll, excitation force, and external force during air vibration, Fig. 6
The figure is a graph showing the force acting on the roll, the excitation force, and the external force during vibration on the road surface, and FIG. 7 is a graph showing the external force acting on the roll and the reaction force from the road surface.

Claims (2)

[Claims] (1) A method for measuring the reaction force that a mass body receives from the road surface when compacting the road surface by applying a vertical vibrational force to the mass body, the method of measuring the reaction force that the mass body receives from the road surface while the mass body is placed on the road surface. From the external force that acts on the mass body when the excitation force is applied,
The road surface reaction method is characterized in that the reaction force that the mass body receives from the road surface is measured by subtracting the external force that acts on the mass body when the excitation force is applied to the mass body while it is suspended from the road surface. Force measurement method. (2) A method of measuring the reaction force that the mass body receives from the road surface when compacting the road surface by applying an excitation force in the vertical direction to the mass body, wherein the mass body is placed on the road surface. The vertical acceleration of the mass body when the vibration excitation force is applied is measured, and the vibration force is subtracted from the value obtained by multiplying the vertical acceleration and the mass of the mass body. Find the external force acting on the mass body, measure the vertical acceleration of the mass body when the excitation force is applied to the mass body while floating from the road surface, and multiply the vertical acceleration by the mass of the mass body. Subtract the excitation force from the above value to determine the external force that acts on the mass body during aerial vibration, and calculate the external force that acts on the mass body during the vibration on the road surface from the external force that acts on the mass body during the air vibration. Subtracting the external force,
A road surface reaction force measuring method, comprising measuring a reaction force that the mass body receives from the road surface.