JPH0548330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a sand level gauge used in the construction of compacted sand piles, and particularly to a sand level gauge using microwaves.

≪Prior art and problems≫ Conventionally, in order to improve the soil quality of soft ground, the so-called sand compaction method has been used, in which sand is buried in the ground and compacted by applying vibrations and shocks to form sand piles. is provided.

In the sand compaction method, a hollow cylindrical sheath is usually buried in the ground, a predetermined amount of sand is poured into the sheath, the sheath is lifted slightly, and the sand ejected at the tip of the sheath is subjected to vibrations and shocks. By adding sand, the sand is compacted, and when compaction has progressed to a certain extent, sand is added into the sheath. By repeating this operation in sequence, a sand pile of a predetermined length is created.

The strength of the formed sand pile is determined by the compaction of the sand. A device that confirms that construction is performed with the specified strength is a sand system that projects ultrasonic waves onto the sand surface and measures the distance between the measurement position and the sand surface based on the time difference between the projection and the reflected wave. A device has been proposed that uses a surface meter to measure the degree of compaction progress from changes in the position of the sand surface.

However, in this type of construction method, pressurized air is usually injected from above the sand surface in order to promote the discharge of sand in the sheath, but the sound of compressed air generated during injection and the impact of compaction and other sand pile construction It was difficult to make accurate measurements due to the mechanical impact noise generated by the work, so measurements of the sand surface had to be carried out after all compaction work and other surrounding work had been stopped.

In addition, when using a measuring device that uses reflected waves, in order to make accurate measurements, it is necessary to install the measuring device in a position where it can effectively project and receive sound waves or radio waves, and to measure over a wide range. There is.

However, in the sand compaction method, a good measurement position is near the upper end of the sheath, which can face the sand surface and block the passage of sand when sand is being introduced. Therefore, if a device with a wide area is installed at this location, it will not be possible to smoothly introduce sand, so when adding sand, the measuring device must be removed first, then the sand will be introduced, and then the device will be turned on again. The removal and installation work also caused delays in the construction period.

This invention was made in view of these problems, and its purpose is to make it possible to measure the sand level at the same time as the compaction work, and to measure the sand level when adding sand. To provide a sand level meter capable of shortening the construction period by moving the measuring device to a position where sand is not obstructed and easily returning the measuring device to the measuring position after sand is being poured.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention is a sand level meter used in a sand compaction method for compacting sand introduced into a hollow cylinder, the sand level meter comprising: A transmitting antenna that is located near the upper end of the hollow cylinder and projects microwaves downward of the hollow cylinder; a receiving antenna that receives reflected waves of the microwave from the sand surface; A processing device that transmits microwaves and calculates the sand surface based on the microwaves and reflected waves received by the receiving antenna, and a protective case that houses the transmitting and receiving antenna and the processing device, the protective case is formed into a flat case with a horizontal axis longer than the vertical axis, and is rotatably mounted in the hollow cylinder, and when the sand is introduced, the horizontal axis of the protective case is positioned in the axial direction of the hollow cylinder. and the horizontal axis of the protective case is positioned perpendicular to the axis of the hollow cylindrical body during measurement.

<<Function>> In the sand level meter with the above configuration, the horizontal axis of the protective case is positioned in the axial direction of the hollow cylindrical body when sand is being introduced, and the horizontal axis is positioned perpendicular to the axis of the hollow body during measurement. Measure the sand surface by reflecting waves. Therefore, when sand is being poured in, it does not interfere with the smooth sand feeding, and during measurement, there are noises such as air jet noise for discharging sand and mechanical impact noise from compaction and other surrounding work. Accurate measurements can be made without being affected by the accompanying sound waves.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show an embodiment of a sand level meter according to the present invention.

In the sand compaction method, sand 12 is poured into a hollow cylindrical body 10 penetrated into the soil.
The sand 12 is discharged from its tip, and the sand 12 is impacted and vibrated through the cylinder 10 to compact it and create a sand pile in the soil. The sand level meter according to the present invention is installed near the upper end of the cylindrical body 10 in order to measure the degree of compaction by measuring the position of the sand surface 12a.

As shown in detail in FIG. 2, the sand level gauge includes a disc-shaped protective case 14 that houses a transmitting antenna 16, a receiving antenna 18, and a processing device 20.
It is roughly composed of.

The transmitting/receiving antennas 16 and 18 are for projecting or receiving microwaves M (900MHz to 1GHz), and are made of a metal plate shaped like a pair of triangular vertices connected as shown in FIG. 2A. It is located on the upper surface side of the protective case 14 so as to cover it.

The processing device 20 is located on the bottom side of the protective case 14 and is electrically connected to the antennas 16 and 18, and includes an oscillator that transmits microwaves M to the transmitting antenna 16 and a reflected microwave M received by the receiving antenna 18. It is comprised of an amplifier for amplification, an arithmetic unit for calculating the sand surface based on the time difference between transmission and reception of the microwave M projected toward the sand surface 12a, a power source battery, and the like.

The protective case 14 has an internal antenna 16,1
8, etc., and is made of a material that does not absorb electromagnetic waves, such as rubber or plastic. An air cylinder 22 for rotating the protective case 14 in any direction is connected to the outside of the body 10 via this shaft.

At the time of measurement, the sand level meter having the above-mentioned configuration is operated so that the air cylinder is perpendicular to the radial direction (horizontal direction) 10 of the flat disk-shaped protective case 14, as shown by the solid line in FIG. The transmitting/receiving antenna 16, 1 is rotated by 22 and located on the top side thereof.
8 is set so as to face the sand surface 12a side.

In this state, the microwave M is projected from the transmitting antenna 16 toward the sand surface 12a below the cylinder 10, and the receiving antenna 18 receives the reflected wave upward after the microwave collides with the sand surface 12a.

Then, the sand surface 12a is measured by the processing device 20 based on the time difference between transmission and reception of the microwave M, and the results are outputted to an appropriate display device and recording device.

At this time, since microwave M is used, which is not affected by surrounding sound waves, measurement can be performed concurrently with compaction work, so unlike conventional methods, compaction work can be performed when measuring the sand surface. and there is no need to interrupt surrounding work.

On the other hand, when the sand 12 is poured in after the measurement, the radial direction of the flat disk-shaped protective case 14 is rotated in the axial direction of the cylinder 10 by the air cylinder 22, as shown by the dotted line in FIG. .

As a result, the sand 12 is smoothly introduced into the cylindrical body 10, and the antennas 16, 18 and the processing device 20 are placed inside the protective case 14, and the sand 12 is smoothly introduced into the cylinder 10.
Failures caused by the input of 2 are prevented.

After adding the sand 12, the protective case 14 is rotated again using the air cylinder 22 and set so that the transmitting/receiving antennas 16 and 18 face the sand surface 12a, and the compaction work and sand surface measurement are resumed. .
The same operation is then repeated to create sand piles of the specified length.

In addition, in the above embodiment of the present invention, the protective case is shown as a flat disk-shaped case, but the protective case used in the present invention is not limited to this, and the point is that it is similar to the case of the above embodiment. It is sufficient that the length in the horizontal direction, that is, the horizontal axis, is longer than the length in the vertical direction, that is, the vertical axis.

<<Effects of the Invention>> As explained above in detail in the examples, the sand level meter according to the present invention is not affected by the sound waves generated inside and outside the cylindrical body into which sand is charged and compacted. Since microwaves are used, accurate measurements of the sand surface can be taken simultaneously with compaction work and other surrounding work without interrupting these works. Furthermore, when sand is being introduced, the protective case can be rotated and moved to a position where it does not interfere with the sand being added, and after sand has been added, the protective case can be easily returned to the measurement position, thereby shortening the construction period.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing the installation state of the sand level meter of the present invention, and FIG. 2 is a plan view of the main part of the sand level meter. 10... Cylindrical body, 12... Sand, 14... Protective case, 16... Transmitting antenna, 18... Receiving antenna, 20... Processing device, 22... Air cylinder.

Claims (1)

[Claims] 1. A sand level gauge used in the sand compaction method for compacting sand put into a hollow cylinder, and the sand level meter is located near the upper end of the hollow cylinder and has a micro-scale toward the bottom of the hollow cylinder. A transmitting antenna that projects waves, a receiving antenna that receives reflected waves of the microwave from the sand surface, and a system that transmits the microwave to the transmitting antenna and based on the reflected wave received by the receiving antenna. It consists of a processing device that calculates the sand surface, and a protective case that houses the transmitting/receiving antenna and the processing device, and the protective case is formed into a flat case whose horizontal axis is longer than the vertical axis. The horizontal axis of the protective case is positioned in the axial direction of the hollow cylindrical body when the sand is introduced, and the horizontal axis of the protective case is aligned with the axis of the hollow cylindrical body during measurement. A sand level gauge characterized by being positioned perpendicular to the sand level.