JPH03221832A - Method and marker for measuring displacement of soil grain - Google Patents

Abstract

PURPOSE:To highly accurately measure the displacement of soil grains by forming transparent plates on one side of a soil tank, sticking plural markers to the insides of the transparent plates so as to optionally slide them, filling the tank with soil, and when pressure is impressed to the upper surfaces of the soil, measuring the displace ment of soil grains by the movement of the markers. CONSTITUTION:Acrylic plates 2a to 2c are engaged with one side of the soil tank 1 whose upper face is opened and plural markers 3 are slidably and regularly stuck to the insides of the plates 2a to 2c. Each marker 3 forms a cross mark on the surface 3b of a circle main body 3a and ruggedness 3d is formed on its rear face 3c. On the other hand, reference fixed points 4 for measuring the movement of the markers 3 are provided on the plates 2a to 2c. The tank 1 is filled with soil E, and while pressing the upper face by a pressing roll 5, the marker 3 is photographed from the front face. Since the markers 3 are moved following the displacement of soil grains based upon the difference of frictional resistance between the front and rear faces of the plates 3a to 3c, relation between the driving state of the roll 5 and the hardening of the soil E can be grasped from the movement of the markers 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a method for measuring the displacement of soil particles in a soil tank when pressure is applied to the top surface of the soil filled in the soil tank, and The present invention relates to a marker suitable for measuring displacement of particles.

[Conventional technology]

For example, when compacting a road surface in civil engineering work, the compaction state inside the road surface cannot be inspected by digging up the road surface under construction, so it must be determined from the road surface.

Therefore, in order to accurately grasp the internal compaction state, it is necessary to investigate the relationship between the compaction work on the road surface and the compaction state inside the road surface through experiments.

Therefore, conventionally, for example, a compaction roll is operated on the top surface of the soil filled in a soil tank for experiments, and the displacement of soil particles in the soil tank at that time is measured, and based on the measurement results, the Experiments are being conducted to investigate the distortion or deformation of the soil.

However, the displacement of soil particles needs to be investigated in detail according to the driving status of the compaction roll, so even in experiments, it is not possible to dig up the soil and examine the displacement of soil particles, and it must be measured externally. Must be.

Conventionally, various techniques such as those described below have been proposed and implemented as methods for externally measuring the displacement of soil particles in a soil tank.

First conventional example: One side of the earthen tank is made of a transparent plate, and
A thin checkered pattern is drawn on the inner surface of the transparent plate (0,
After pasting a rubber membrane (approximately 2 mm thick) with the lattice pattern facing outward using grease or the like, the soil tank is filled with soil. Then, when pressure is applied to the soil surface, the displacement of the soil particles is transmitted to the rubber membrane and the grid pattern is deformed, so the displacement of the soil particles can be measured based on the deformation of the grid pattern visible through the transparent plate. .

Second conventional example: A plurality of small-diameter lead works are embedded in the soil in a soil tank, and the positions of the lead works are determined by irradiation with radiation and photographed, and the displacement of soil particles is measured.

Third conventional example: After filling the earth tank with soil, the transparent side wall of the earth tank is removed, marks are drawn directly on the exposed soil surface, and the side wall is reattached. Then, the displacement of the soil particles is measured by the movement of the mark visible through the transparent plate.

[Problem to be solved by the invention]

However, the above conventional technology has the following problems.

That is, in the first conventional example, when the pressure applied to the top surface of the soil is released, the deformed rubber membrane restores itself due to its own elastic force, so that the compaction roll passes through the soil. There is a problem in that there is a large discrepancy between the amount of displacement of the soil particles and the amount of deformation of the rubber membrane.

The rubber film has a large friction with the side wall plate, and it is necessary to attach it to a transparent plate through grease etc. for lubrication, so the shear resistance of the grease becomes an obstacle, and the rubber film prevents the displacement of soil particles. It is not possible to accurately follow the deformation of the grease, and furthermore, the viscosity of grease changes depending on the temperature, etc., so there is a problem that temperature control must be carried out during experiments.

In addition, in the second conventional example, since radiation is used,
It may have an adverse effect on the human body, requires a qualification to handle it, and the equipment is expensive. Since the difference in specific gravity between the soil and the lead work is large, there is a problem that a large discrepancy occurs between the displacement of the soil particles and the displacement of the lead work, and the reliability of the measured value is low. There is also the disadvantage that the strength of the soil changes when there are a large number of lead works.

Furthermore, although there is no problem with the third conventional example for roughly measuring the displacement of soil particles, it is not suitable for measuring fine displacements, so it is recommended that it be used for high-precision analysis. It is not possible to obtain accurate data.

Therefore, the present invention was made by focusing on the unresolved problems of the conventional technology, and is an object of the present invention to measure the displacement of soil particles in a soil tank with high precision without causing a significant increase in cost. The purpose of the present invention is to provide a method for measuring soil particle displacement, and a marker for measuring soil particle displacement suitable for the measurement.

[Means to solve the problem]

In order to achieve the above object, the method for measuring displacement of soil particles according to claim (1) comprises forming at least one side of a soil tank with a transparent plate, and attaching a plurality of markers to the inner surface of the transparent plate in a slidable manner. Then, fill the soil tank with soil, and measure the displacement of the soil particles in the soil tank based on the behavior of the marker when pressure is applied to the top surface of the soil filled in the soil tank. do.

In addition, the soil particle displacement measurement marker according to claim (2) includes:
A marker used in the method for measuring soil particle displacement according to claim (1) above, wherein the sheet faces the transparent plate and has a mark printed on its smooth surface, and has unevenness formed on its back surface facing upward. Consisting of

Furthermore, the soil particle displacement measuring method according to claim (3) is the soil particle displacement measuring method according to claim (1), wherein marks are printed on the smooth surface facing the transparent plate side and facing upward. A marker made of C.I. with unevenness formed on the back surface is used, and the marker is attached to the inner surface of the transparent plate through water.

[Effect]

In the invention set forth in claim (1), when the soil particles are displaced by the pressure applied to the upper surface of the soil, the plurality of forces attached to the inner surface of the transparent plate are moved, so that the markers are Based on the movement, the displacement of the soil particles is measured.

Since the behavior of each marker is independent of the behavior of other markers, even if the pressure applied to the top surface of the soil is released, the position of the marker will not be restored.

Furthermore, in the invention described in claim (2), since the surface of the marker is smooth, the frictional resistance between the marker and the transparent plate is extremely small, and since the back surface of the marker is uneven, it is possible to avoid dirt. and the marker mesh with each other, and the displacement of the soil particles is transmitted to the marker with high accuracy, so that the marker moves to accurately follow the displacement of the soil particles. And since the marker is in sheet form, there is no risk of affecting the strength of the soil.
It is possible to attach the marker without the use of highly adhesive grease or the like, and the mark printed on the surface of the marker makes it easy to measure the displacement of the marker.

In the invention described in claim (3), the above claim (1)
) and (2), and the water interposed between the marker and the transparent plate has a low viscosity (most of it evaporates while filling the soil tank with soil). Therefore, as long as there is no freezing, it will not interfere with the movement of the marker.

〔Example〕

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

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention.

That is, as shown in FIG. 1, a box-shaped earthen tank 1 with an open upper surface has transparent acrylic plates 2a, 2 on a part of its lower side.
b and 2c are fitted so that the inside can be seen from the outside.

Note that the acrylic plates 2a to 2c are susceptible to bending or breakage due to the pressure of the soil in the soil tank 1, so they are formed to a thickness (about 30 mm) that provides sufficient strength.

A plurality of markers 3 are regularly and slidably attached to the inner surface of each acrylic plate 2a to 2C (the surface facing the inside of the earthen tank 1). In addition, in this example, the arrangement density of the markers 3 was made higher as the upper acrylic plate is placed.When pressure is applied to the upper surface of the soil in the soil tank 1, the closer to the upper surface the soil particles are affected by the pressure. This is because the displacement is complicated.

Moreover, an immovable reference fixed point 4 for measuring the behavior of the marker 3 is provided at a predetermined position on each of the acrylic plates 2a to 2C.

Here, as shown in FIG. 2(a) which is a front view and FIG. 2(b) which is a side view, the marker 3 has a circular sheet-like main body 3a, and the main body 3a has a smooth surface. surface 3b
A cross mark is printed on the back side 3C, and unevenness 3d is formed on the back side 3C.

Furthermore, if the main body 3a is too hard, the adhesion of the markers 3 to the acrylic plates 2a to 2c will deteriorate, making it difficult to stick them.On the other hand, if the main body 3a is too soft, the movement of soil particles, which will be described later, will cause the markers 3 to stick to the acrylic plates 2a to 2c. Since there is a possibility that the marker 3 may peel off from the plates 2a to 2c, the hardness of the main body 3 is determined in consideration of these factors.

Therefore, the main body 3a is preferably molded from polyester or Tetron, for example, but may be made of other materials.

According to experiments conducted by the present inventors, the main body 3a has a diameter of 5
Forming to a size of ~8M and a thickness of about 0.03mm yielded the best results in terms of work efficiency during sticking and ability to follow the displacement of soil particles.

Further, the unevenness 3d can be formed by applying a thin layer of adhesive to the back surface 3c of the main body 3a in advance, and using the adhesive to laminate, for example, soil particles or the like on the back surface 3C.

The marker 3 is attached with the surface 3b of the main body 3a facing the acrylic plates 2a to 2c via water.

That is, water sticks the markers 3 to the acrylic plates 2a to 2c due to its surface tension, but the resistance in the shearing direction is extremely small and evaporates while filling with soil, and the surface 3b of the main body 3a is smooth. Therefore, the marker 3 can freely move on the back surfaces of the attached acrylic plates 2a to 2C.

Note that since the marker 3 is extremely lightweight, it moves even in response to minute external forces.

Note that the marker 3 may be attached using a material other than water (for example, grease, etc.), but if it is attached using a material that is too viscous, the ability of the marker 3 to follow the displacement of soil particles will be poor. , it becomes impossible to accurately measure the displacement of soil particles.

Furthermore, the soil tank 1 is filled with soil E.

However, the soil E is filled after the markers 3 are pasted on the back surfaces of the acrylic plates 2a to 2c.

Then, as shown in FIG. 1, the compaction roll 5 is driven to compact the upper surface of the soil E, and each time the compaction roll 5 advances a predetermined distance, the marker 3 is inserted through the acrylic plates 2a to 2'c. Take a photo from the front.

Here, when the compaction roll 5 rolls, the upper surface of the soil E is pressurized, so that the soil particles inside are displaced and the soil E is gradually compacted.

Then, when the soil particles of soil E are displaced, the back surface 3 of marker 3
The unevenness 3d formed on the soil E engages with the soil particles of the soil E, and as mentioned above, the acrylic plates 2a to 2c and the marker 3
Since the frictional resistance between the marker and the surface 3b is extremely small, the marker 3 moves following the displacement of the soil particles.

Therefore, the relationship between the driving state of the compaction roll 5 and the compaction of the soil E can be grasped from the behavior of the marker 3 shown in the photograph taken as the compaction roll 5 advances.

Therefore, the movement of the marker 3 shown in the photograph is read into an analysis device such as a computer.

For example, the reading method is to place the photos one by one on an XY moving table in the order in which they were taken.
The photograph is enlarged and displayed on a monitor using a video camera or the like. Then, the worker operates the controller while monitoring the monitor to move the photo on the XYl moving table, and sets the coordinates of the cross mark of marker 3 in the photo with reference to the reference fixed point 4 in the photo. It is sufficient to sequentially read the markers 3 as points, transmit their coordinate values to the analysis device, do this for all the photographs taken, and have the analysis device record the behavior of each marker 3 as a data string.

The analysis device analyzes the stress distribution and strain within the soil E using the obtained data string and according to a predetermined processing procedure, for example, using an analysis method used in the finite element method.

As a result, the relationship between the driving status of the compaction roll 5 and the compaction status of the soil E can be quantitatively grasped.

In the above embodiment, since no attractive force or repulsive force is exerted between each marker 3 and other markers 3, even when the compaction roll 5 passes, the individual marker 3 does not return to the position before movement. As mentioned above, since the displacement of the soil particles is accurately followed, the displacement of the soil particles can be measured with high precision.

Z Furthermore, since the marker 3 is in the form of a thin sheet and the unevenness 3d formed on the back surface 3c does not need to be extremely thick, there is no fear that it will affect the strength of the soil E.

Furthermore, since an expensive device such as a radiation irradiation device is not required, there is no need for a significant increase in cost.

In the above embodiment, the case where the marker 3 is circular has been described, but it goes without saying that it may have another shape, and the mark printed on the surface thereof is not limited to the 10 mark.

Furthermore, in the above embodiment, a case has been described in which the unevenness 3d is formed by laminating soil particles etc. on the back surface 3c of the marker 3 via an adhesive.
Other means may be used as long as d is formed.

〔Effect of the invention〕

As explained above, according to the invention set forth in claim (1), the displacement of soil particles in a soil tank is measured based on the behavior of a plurality of markers attached to a slidably transparent plate. This has the effect of making it possible to measure the displacement of soil particles with high precision.

According to the invention described in claims (2) and (3),
Since the marker follows the displacement of the soil particles with high precision, the displacement of the soil particles can be measured with even higher precision.

[Brief explanation of drawings]

FIG. 1 shows the constituent countries of an embodiment of the present invention, FIG. 2(a) is a front view of a marker applied to this embodiment, and FIG. 2(b) is a plane view of the same marker.

Claims (3)

[Claims] (1) At least one side of the soil tank is made up of a transparent plate, a plurality of markers are slidably pasted on the inner surface of the transparent plate, and then the soil tank is filled with soil, and the soil tank is filled with soil. A method for measuring displacement of soil particles, the method comprising measuring the displacement of soil particles in a soil tank based on the behavior of the marker when pressure is applied to the top surface of the filled soil. (2) The soil particle displacement measurement according to claim (1), characterized in that the sheet is made of a sheet having a mark printed on the smooth surface facing the transparent plate side and unevenness formed on the back surface facing upward. A marker for measuring soil particle displacement used in the method. (3) Use a marker made of a sheet with a mark printed on the smooth surface facing the transparent plate and an uneven surface on the back side facing upward, and apply the marker to the transparent plate through water. The soil particle displacement measuring method according to claim (1), wherein the method is applied to an inner surface of a soil particle.