JP2000160542A - Sand surface detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and accurately detectable sand surface detecting device becoming no hindrance to supplying earth and sand and requring no acting of a new member or water and compressed air. SOLUTION: This device is to detect the sand surface in a sand pile creating hollow pipe 2 of earth and sand 12 inputted to the sand pile creating hollow pipe 2 driven in the processing ground 1. In this case, the device is provided with a microstrip antenna 13 installed on an inner wall of the sand pile creating hollow pipe 2, a network analyzer 8 for receiving a reflected wave from the sand surface through the microstrip antenna 13 by inputting a high frequency sweep signal to the sand pile creating hollow pipe 2 through the microstrip antenna 13 by generating the high frequency sweep signal and an arithmetic processing unit 11 for performing an operation for detecting the sand surface on the basis of frequency characteristic data on the reflected wave received by the network analyzer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for forming sand pits in a treated ground to reinforce and stabilize the ground. The present invention relates to a device for detecting a sand surface.

[0002]

2. Description of the Related Art Conventionally, in the case of reinforcing soft ground or erection of a pier on the seabed, a hollow pipe for sand pit formation is cast, and earth and sand which is a sand pit material is poured into the pipe. Deposits are being made. FIG. 5 shows an example of an apparatus for this purpose.
As shown, a hollow tube 2 for sand formation in a treated ground 1.
Is poured by the vibrating device 3, and the earth and sand is introduced from the earth and sand supply port 4, and is deposited on the bottom of the hollow tube 2 for sand formation. The loading of the earth and sand is controlled by an opening and closing hatch 5 provided at the lower end of the earth and sand supply port 4. Further, the inside of the sand pit forming hollow tube 2 is pressurized by compressed air through a compressed air supply / exhaust pipe 6 and decompressed by exhaust gas. A coaxial waveguide converter 7 for exciting the tube 2 as a circular waveguide is provided. The coaxial waveguide converter 7 is connected to a network analyzer 8, inputs a high-frequency sweep signal generated by the network analyzer 8 into the hollow tube 2 for sand formation, and outputs a reflected wave from the sand surface. It receives and sends the received signal to the network analyzer 8. The driving depth of the sand pit formation hollow tube 2 into the processing ground 1 is measured by a depth gauge 9, and a control processor 10 controls the driving and pulling out of the sand pit formation hollow tube 2. Further, the control processor 10 and the network analyzer 8 are connected to a computer 11 for controlling the whole, and the computer 11 performs an operation for detecting a sand surface position from the frequency characteristic data obtained by the network analyzer 8.

In the sand formation, first, the hollow tube 2 for sand formation is vibrated by the vibration device 3 and is driven into the treated ground 1 to a predetermined depth D. Next, the opening / closing hatch 5 is opened, and the earth and sand is supplied from the earth and sand supply port 4 and is charged into the hollow pipe 2 for sand formation. By this charging, earth and sand 12 having a height H is deposited on the bottom of the hollow tube 2 for sand formation. In this state, the opening / closing hatch 5 is closed, and thereafter, the compressed air is supplied into the sand-producing hollow tube 2 through the compressed-air supply / exhaust pipe 6 to pull out the sand-producing hollow tube 2 while pressurizing the inside of the tube. Go. During this withdrawal, sand pits are formed in the processing ground 1, and at the same time, the depth D of the hollow pipes 2 for sand formation from the processing ground 1 is measured by the depth gauge 9, and the control processor 10 controls the depth D. Processing of the measured value is performed. At the same time, the network analyzer 8 generates a swept high-frequency signal from the built-in high-frequency oscillator, and sends the swept high-frequency signal from the coaxial waveguide converter 7
And then switch to the reflection characteristic mode to detect the reflected wave from the sand surface. And computer 1
In step 1, the sand surface (H) is calculated based on the frequency characteristics of the reflected wave using a predetermined arithmetic expression.

[0004]

However, in the sand surface detecting device configured as described above, the coaxial waveguide converter 7 is not used.
Is protruded from the inner wall of the sand-producing hollow tube 2, not only hinders the passage and fall of the earth and sand supplied from the earth and sand supply port 4, but also prevents the coaxial waveguide converter 7 from passing. It may also cause the earth and sand to adhere and lower the detection accuracy. Further, in some cases, the coaxial waveguide converter 7 may be damaged by the impact of earth and sand. To cope with the above-described problems, Japanese Patent Application Laid-Open No. 8-41854 discloses that the coaxial waveguide converter 7 has a folded dipole shape or that an eaves or impeller-like rotation is provided above the coaxial waveguide converter 7. To attach the body,
It is described that countermeasures such as applying water or compressed air to the coaxial waveguide converter 7 are taken. However, with these countermeasures, in the case of the folded dipole type, it is still the same as being protruded from the inner wall of the hollow pipe 2 for sand formation, and the problem of breakage still remains, and the eaves and the like still remain. When adding new members, maintenance is required in addition to the cost of the members themselves, and when applying water or compressed air, the running cost is increased and the apparatus becomes complicated.

Accordingly, an object of the present invention is to provide an inexpensive and accurate sand surface detection which does not hinder the supplied earth and sand, and does not require the use of new members or the action of water or compressed air. It is to provide a device.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to detect a sand surface of earth and sand introduced into a hollow pipe for sand formation formed on a treated ground according to the present invention. A microstrip antenna mounted on the inner wall of the sand-producing hollow tube, generating a high-frequency sweep signal, and transmitting the high-frequency sweep signal to the sand-producing hollow tube via the microstrip antenna. A network analyzer for inputting and receiving a reflected wave from a sand surface via the microstrip antenna, and an operation for performing an operation for sand surface detection based on frequency characteristic data of the reflected wave received by the network analyzer And a processing device.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. In the sand surface detection device of the present invention, a microstrip antenna 13 is mounted on the inner wall of the sand tube 2 for sand formation instead of the coaxial waveguide converter 7 of the sand surface detection device described with reference to FIG. It is characterized by having done. The structure of the microstrip antenna 13 may be a known one. For example, as shown in FIG. 2, a dielectric 16 and a patch 16 made of a metal plate are sequentially laminated on a base metal 14, and It is curved to the same curvature as the inner wall of the hollow tube 2 for use. Preferably, the surface of the patch 16 is protected by a dielectric material. Although the microstrip antenna 13 may be fixed on the inner wall surface of the hollow tube 2 for sand formation, as shown in FIG. Matching recess 17
And the microstrip antenna 1 is provided in the recess 17.
It is particularly preferred to bury 3. As shown in FIG. 3, the input / output lead 18 of the microstrip antenna 13 is made to pass through the sand-producing hollow tube 2 so as to be taken out.

The area of the patch 16 of the microstrip antenna 13 is not particularly limited, and the size (diameter and overall length) of the hollow tube 2 for sand formation and the wavelength of a high-frequency sweep wave used for measurement are taken into consideration. Is set as appropriate. Further, in order to minimize the detection error, the microstrip antenna 13 is arranged to start from the highest position in the reflection path of the hollow pipe 2 for sand formation, and to perform λ / 4 of the high-frequency sweep wave used for measurement.
It is preferable to mount at a separated position.

Since the microstrip antenna 13 is a flat surface and does not protrude from the inner wall surface of the hollow pipe 2 for sand formation, it does not hinder the supply of earth and sand, and there is no possibility of breakage. In addition, since it is a vertical surface, the earth and sand do not fall naturally and adhere to it, and there is no need to apply water, compressed air, or the like.

The members other than the microstrip antenna 13 may be the same as those of the sand surface position detecting device shown in FIG. To give a supplementary explanation, a high frequency sweep signal in the range of 160 to 250 MHz is generated from the network analyzer 8 and the microstrip antenna 13 is generated.
Through the hollow pipe 2 for sand formation. Then, the high-frequency sweep signal propagates through the inside of the sand-producing hollow tube 2 toward the sand surface, the reflected wave is received by the microstrip antenna 13, and the received signal is sent to the network analyzer 8.

Here, the principle of detecting a sand surface by a sweep signal will be described. In general, assuming that a transmission wave is emitted toward an object separated from the antenna by a distance L and a reflected wave is received after a time t, the following relationship is obtained: t = 2L / C (1). Here, C is the speed of light. Therefore, t
Is measured, the distance L can be calculated. At this time, as shown in FIG. 4, if a sweep wave whose frequency repeatedly increases and decreases linearly during the sweep time T is used as the transmission wave, the emission frequency fs and the reflection frequency fr are shifted by the time difference t. And overlap. And
Assuming that the modulation frequency (the maximum change amount of the frequency) by this sweep is F and the frequency difference at the time difference t is fb, there is a relationship of fb / F = t / T (2). From equation (2), D = C · fb · T / 2F (3) is obtained. Therefore, the distance D can be calculated by measuring the frequency difference fb (= fs−fr). The above sweeping operation is performed by the network analyzer 8, and the calculation is performed by the computer 11.

Various modifications can be made to the sand surface detecting device of the present invention. For example, instead of the patch 16 of the microstrip antenna 13, a microstrip line may be used. Further, as described in Japanese Patent Application Laid-Open No. 8-41854, a predetermined reference position is set, and the above arithmetic expression is changed so as to calculate the sand surface from a relative distance from the reference position, thereby detecting the sand surface. Can also be performed.

[0013]

As described above, according to the sand surface detecting device of the present invention, since there is no projecting member in the hollow pipe for sand formation, there is no possibility of adhesion or breakage of earth and sand, and no maintenance is required. Becomes Furthermore, since there is no need to act on water or compressed air, there is no running cost. In this way, it is possible to eliminate all the problems that have conventionally occurred when supplying earth and sand.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a sand surface detection device of the present invention.

2A and 2B are a perspective view and a cross-sectional view illustrating an example of a microstrip antenna.

FIG. 3 is a cross-sectional view showing a state in which the microstrip antenna is embedded in a hollow tube for sand formation.

FIG. 4 is a diagram for explaining a principle of detecting a position of an object by a sweep signal.

FIG. 5 is a schematic diagram showing a configuration of a conventional sand surface detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing ground 2 Hollow pipe for sand formation 3 Shaking device 4 Sediment supply port 5 Opening / closing hatch 6 Compressed air supply / exhaust pipe 7 Coaxial waveguide converter 8 Network analyzer 9 Depth gauge 10 Control processor 11 Computer 12 Sediment 13 Microstrip antenna 14 Metal 15 Dielectric 16 Patch 17 Concave part 18 Lead wire

Claims (3)

[Claims] 1. An apparatus for detecting a sand surface of earth and sand introduced into a hollow pipe for sand formation formed on a treated ground, in the hollow pipe for sand formation. A microstrip antenna mounted on the inner wall of the hollow tube, generating a high-frequency sweep signal, inputting the high-frequency sweep signal through the microstrip antenna to the hollow tube for sand formation, and transmitting a reflected wave from a sand surface to the microstrip. A network analyzer for receiving via a strip antenna; and a sand surface, comprising: an arithmetic processor for performing an operation for sand surface detection based on frequency characteristic data of the reflected wave received by the network analyzer. Detection device. 2. The sand-surface positioning device according to claim 1, wherein the microstrip antenna is embedded so as to be flush with an inner wall of the sand-producing hollow tube. 3. The microstrip antenna according to claim 1, wherein the microstrip antenna is mounted at a position separated by λ / 4 of a high-frequency sweep wave to be used from a highest position in a reflection path of the hollow tube for sand formation. The sand surface detecting device according to claim 1.