JPS61218910A - Measuring system for subsided quantity of ground - Google Patents

Abstract

PURPOSE:To measure movement or subsidence of ground precisely by laying plural high-frequency coils under the underground to be measured in the direction of the depth in order making the axial direction parallel and detecting the magnetic force sent out from these coils with a magnetic coil with two axes. CONSTITUTION:The electromagnetic coil 1 detecting generating signals of the high-frequency coils 4-1-4-n is constituted with two axes of a Z direction and an X direction so that the positions of the high-frequency coils can be discriminated from the magnetic flux direction and force of the generating signals. Since the high-frequency signals become smaller in inverse proportion to a square - cubic of the distance when the distance from the signals to the high- frequency coils is separated, the winding with a number of times of winding is performed on a magnetic core with high permeability so that the weak signals can be detected. Th high-frequency signals from an oscillator 6 are amplified and given to the high-frequency coils 4-1-4-n and the high-frequency signals sensed with the coils indicating the Z direction of the electromagnetic coil 1 and the high-frequency signals sensed with the coils indicating the X direction of the coil 1 are received with a receiver 2a and a receiver 2b respectively.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] [Prior art] In recent years, on mountain slopes and land development areas.

Measuring the movement of the ground and the amount of subsidence has been raised as an important issue. This type of measurement method is generally applied to mainly measure changes in the ground surface, such as triangulation and leveling; it is rarely used to measure underground movement. This is the current situation.

To provide a method for measuring the amount of ground subsidence that can accurately detect the amount of ground subsidence.I: Yes.

[Structure of the invention]

The method of measuring the amount of ground subsidence according to the present invention is to bury a sheet vertically inside the ground with the axes of a plurality of high-frequency coils parallel to each other and installed in the vertical direction. An electromagnetic coil composed of 92 axes is suspended in a hole vertically polled inside the ground at a distance, and the plurality of high-frequency coils are excited from the ground by the output of an oscillator, and the electromagnetic coil is The magnetic force transmitted from each of the high-frequency coils is detected by the two-axis sensor of the electromagnetic coil by movement of the hole in the depth direction.

This is shown in a diagram. In this figure, 1 is an electromagnetic coil, 2a and 2b are receivers, and 3a is a receiver.

3b is a synchronous detector, 4-1 to 4-n are high frequency coils, 5
is an amplifier, 6 is an oscillator, 7 is an arithmetic unit, 8 is a recorder, 9
is a waveform analyzer. this house.

Each of the high frequency coils 4-1 to 4-n is a thin linear magnetic material having a high saturation magnetic flux density and wound with enameled wire or the like. The number of winding layers should not be large since n winding layers are installed at regular intervals within the sheet. To generate high frequency signals that reach far away,
A material that has a high magnetic flux density and is difficult to saturate is used as the magnetic core. Its materials include pure iron and silicon steel.

Fe-Co-V alloy etc. are suitable. In addition, in order to strongly excite the magnetic core with high frequency, it is suitable to use thin wires whose surfaces are oxidized and bundled together. this is.

This is to reduce power loss due to eddy currents.

This loss of power is dissipated as heat and may corrode the bellows-like sheet, so care must be taken. or,
Since these high-frequency coils are buried underground, they can be molded with electrically insulating resin to prevent leakage of electrical signals.

The electromagnetic coil 1 that detects the signals generated by the high-frequency coils 4-1 to 4-n is configured with two axes in two directions and the X direction so that the position of the high-frequency coil can be determined from the magnetic flux direction and strength of the generated signals. has been done. As this high-frequency signal increases the distance from the high-frequency coil, it decreases in inverse proportion to the square to the cube of the distance. Therefore, in order to sufficiently detect the weak high-frequency signal, the number of turns on the magnetic core with high magnetic permeability must be increased. It has many windings.

A high frequency signal generated by one oscillator 6 is amplified by an amplifier 5 and applied to the high frequency coils 4-1 to 4-n. On the other hand, the high frequency signals sensed by the coils indicating the two directions of the electromagnetic coil 1 are received by the receiver 2a, and the high frequency signals sensed by the coils indicating the X direction are received by the receiver 2b. The synchronous detectors 3a and 3b are connected to the receivers 2a and 2b, respectively.
The received signal received from the oscillator 6 is synchronously detected by the output signal of the oscillator 6. Through this synchronous detection.

Both outputs are given to a computing unit 7, where the phase relationship between the two is measured so that initial positioning with respect to the high frequency coil and subsequent positional deviation of the high frequency coil can be measured. Furthermore, by using the waveform analyzer 9 in the measurement system, it is possible to adapt to the complex ground 1 in the urban area i. Note that the recorder 8 is used to record measurement results.

FIG. 2 is a diagram showing an example of setting states of the high frequency coil and the electromagnetic coil in the embodiment of FIG. 1. In this figure, reference numeral 11 indicates a bellows-shaped sheet on which high-frequency coils 4-1 to 4-n are mounted. Usually, this sheet is disposable, so one made of vinyl is suitable. As another example, high frequency coils 4 are placed at regular intervals on a mesh sheet.
-1 to 4-n may be attached. High frequency coil 4-1~
4-n are attached to the sheet 11 in parallel alignment, and are buried in holes perpendicularly drilled in the ground at the location to be measured. ``This hole will be filled after the sheet 11 is buried.

The electromagnetic coil 1 is suspended into a hole 12 made parallel to the buried sheet 11 at a certain distance. The connection wires of the high frequency coils 4-1 to 4-n and the electromagnetic coil 1 are led to the ground equipment 10, and the output terminals of the amplifier 5 and the receiver 2 housed therein are respectively guided to the ground equipment 10.
It is connected to the input terminals a and 2b.

In the measurement, first, when the sheet 11 is buried, the magnetic force sent out from each high-frequency coil is received while moving the magnetic coil 1 inserted into the hole 12 in the depth direction.

The result is recorded on the recorder 8 as shown in FIG. 3(a). Next, for example, let us assume that a similar measurement is carried out one year later or ten years later and results as shown in FIG. 9(b) are obtained. By comparing the recorded results in Figure 3 (a) and (b) obtained in this way and measuring the difference z1 (or Z2), the moving position of the high-frequency coil, that is, the amount of ground subsidence can be measured. be able to.

In addition, in the above embodiment, the high frequency coils 4-1 to 4
-n are preferably buried in the horizontal direction and aligned in either the X direction or the Y direction. Further, it is necessary to set the sense axis of the detection magnetic coil 1 in advance in the direction in which the maximum detection output is obtained so that the sense axis is the same as the direction of the beam generated by the high-frequency coil 1.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a plurality of high-frequency coils are sequentially buried underground in the ground to be measured with their axial directions parallel to each other in the depth direction.

By detecting the magnetic force sent out from these coils using biaxial magnetic coils, it becomes possible to accurately measure ground movement and subsidence.

It has great benefits when used to determine the presence or absence of dangers from landslides and to investigate the ground.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention;
FIG. 2 is a diagram showing an example of setting states of the high-frequency coil and electromagnetic coil in the embodiment of FIG. 1, and FIG. 6 is a graph showing an example of measurement data obtained by moving the electromagnetic coil in FIG. 2. It is. In the figure, 1 is an electromagnetic coil, 2a and 2b are receivers, and 3
a and 3b are synchronous detectors, 4-1 to 4-n are high-frequency coils, 5 is an amplifier, 6 is an oscillator, 7 is an arithmetic unit, 8 is a recorder, 9 is a waveform analyzer, 11 is a sheet, and 12 is a polling device. It's a hole. Preface 2

Claims (1)

[Claims] 1. A sheet installed vertically with the axes of multiple high-frequency coils parallel to each other is buried vertically inside the ground,
An electromagnetic coil consisting of two shafts is suspended into a hole bored vertically inside the ground at a certain distance from the buried sheet, and the plurality of high-frequency coils are connected to the output of an oscillator from the ground. The magnetic force transmitted from each of the high-frequency coils is detected by the two-axis sensor of the electromagnetic coil by the movement of the electromagnetic coil in the depth direction of the hole. Measurement method.