JPH10185633A - Underground displacement measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] An object is to provide a device that can easily measure not only a vertical direction but also a horizontal direction with respect to gravity and that can easily detect a wide-angle angle in real time. And [Constitution] In a device in which an underground displacement meter is inserted into a boring hole 63 at an underground displacement measurement point to obtain an underground displacement, the underground displacement meter has a connecting rod portion 29 and a sensor rod portion. The sensor rod 30 is connected to
It comprises a sensor unit 31 for detecting an angle from a change in a gap due to an inclination, and a converter unit 32 for converting a detection signal of the sensor unit 31 into an electric signal. With such a configuration,
Many measurement points can be measured, and the measurement can be performed in both the horizontal direction and the vertical direction only by changing the direction of the sensor unit 31. In addition, the length in the longitudinal direction can be made extremely small. Further, the calculation of the angle is simple, and the configuration of the underground displacement meter 28 can be made robust, which is favorable for detecting the underground displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground displacement measuring device for observing the behavior of a ground, railway, or embankment 13 of a motorway for disaster prevention.

[0002]

2. Description of the Related Art In a disaster countermeasure or disaster prevention business, a measurement task of observing the behavior of a ground 11 or an embankment 13 in a mountain area occurs. In this measurement work, various measurement methods are used. One of the methods is to drill a vertical boring hole at a measurement point as shown in FIG. 11 (a), or as shown in FIG. 11 (b). By digging horizontal boring holes and examining the displacement and deformation in these holes with a rod-shaped inclinometer 12, the landslide surface in the landslide mass 11 and landslide can be specified, and the behavior of the ground 11 and embankment 13 can be determined. Can be caught.

Conventionally, as a method of grasping the displacement and deformation state of the borehole, from the viewpoint of cost and reliability, there are the following methods. 1. a differential transformer system; The strain gauge method has been widely used. These two types will be described below. 1. Differential Transformer As shown in FIG. 12B, the differential transformer 21 includes a primary coil 18 connected to a drive oscillator 20 and a secondary coil 19 connected symmetrically and in the opposite direction. The iron core 17 is inserted into the center space of the bobbin in a donut shape in a non-contact state, and is divided into two parts by a change in the relative position between the iron core 17 and the primary and secondary coils 18 and 19. Further, the mutual inductance of the secondary coil 19 with respect to the primary coil 18 changes, causing a difference in the induced electromotive voltage of the secondary coil 19, and the difference is obtained as an output to the output transformer 22.

[0004] In a device for detecting inclination using the principle of such a differential transformer 21, as shown in FIG. 12 (a), a weight 14 is hung on a hanging string 15 of a pendulum 16, The core 17 is integrally attached.
With this configuration, when the object to be measured is tilted, the pendulum 16 is maintained in the vertical state, and the primary coil 18 and the secondary coil 19 are tilted, so that the tilt is detected based on the relative movement distance of the iron core 17. .

[0005] 2. Strain gauge method The X-direction strain gauge 24 (or the Y-direction strain gauge 25) as shown in FIG. 13 measures the surface strain of the object to be measured by changing the resistance value of the metal resistance element. Generally, the resistance value of a metal material has a property of increasing when stretched and decreasing when compressed when an external force is applied.
For example, assuming that the length of the first one is elongated by Δ1 (the distortion at that time is Δ1 / 1 = ε), and if the resistance value which was initially R changes by ΔR, the following relationship is established. . ΔR / R = KSε KS is called a gauge factor and is a coefficient representing the sensitivity of the strain gauge.

As shown in FIG. 13 (a), the X-direction strain gauge 24 and the Y-direction strain gauge 25 are adhered to the pipe 23 in the X-direction and the Y-direction, respectively, and their outputs are output. As shown in FIG. 13B, it is connected to one side of the bridge circuit 27. The change in the amount of distortion of the pipe 23 is detected based on how the output from the output transformer 22 with respect to the input voltage from the input terminal 26 is changed by the X-direction strain gauge 24 (or the Y-direction strain gauge 25).

[0007]

[Problems to be solved by the invention]

1. The differential transformer system has features such as being less susceptible to temperature changes due to the compensation structure of the differential transformer 21 itself, and being non-contact, so that the conversion unit is less likely to deteriorate. On the other hand, because of the pendulum structure, there is a problem that it is difficult to reduce the scale in the longitudinal direction.

[0008] 2. The strain gauge method has a feature that the structure is simple and therefore, the manufacturing is easy. But,
In order to detect a change in the angle, it is necessary not only to attach a large number of X-direction strain gauges 24 or Y-direction strain gauges 25 for each predetermined angle, but also it is troublesome to calculate the angle based on each gauge output. When the pipe 23 is inclined without distortion, there is a problem that the change in the angle cannot be measured.

According to the present invention, it is possible to easily measure not only the vertical direction but also the horizontal direction with respect to gravity, which has been difficult with the differential transformer method, and it is also possible to easily detect a wide area angle in real time. It is intended to provide a device.

[0010]

According to the present invention, there is provided an underground displacement measuring apparatus in which a boring hole 63 is drilled at an underground displacement measuring point and an underground displacement meter 28 is inserted to obtain an underground displacement. The underground displacement meter 28 is formed by connecting a connecting rod 29 and a sensor rod 30. The sensor rod 30 includes a sensor unit 31 for detecting an angle from a change in a gap due to an inclination, and a sensor unit 31 for detecting an angle. And a converter unit for converting the detection signal into an electric signal.

Since the sensor unit 31 for detecting an angle from a change in the gap due to the inclination and the converter unit 32 for converting the detection signal into an electric signal are provided, many measuring points can be measured in real time, Both the direction and the vertical direction can be measured simply by changing the direction of the sensor unit 31. In addition, the length in the longitudinal direction can be made extremely small. When the sensor unit 31 is tilted, the spring 47
The suspended target 46 moves in the inclined direction, and the distance D from the probe 48 changes. A correlation is obtained between the change in the distance D and the oscillation voltage of the probe 48. The relevant and accurate output signal is output from the probe 48. Accordingly, the calculation of the angle is simple, and the configuration of the underground displacement meter 28 can be made robust, which is favorable for detecting the underground displacement.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. The underground displacement meter 28 used in the underground displacement measuring device of the present invention has a sensor rod 3 as shown in FIG.
0 and the connecting rod 29, for example, a unit length of 1 m
Is formed in a long rod-like shape such as a clothesline in which the underground displacement meters 28 are sequentially connected to a length of several meters to several tens of meters. Such an underground displacement meter 28 is formed by vertically drilling a borehole 63 at a measurement point such as the ground 11 to be measured, and is inserted therein. In this case, the lowermost end of the underground displacement meter 28 is inserted into a deep and stable stratum that is not likely to cause a landslide, and as shown in FIG. It is desirable to set so that the middle of the total 28 is inclined.

As shown in FIGS. 2 to 4, the sensor rod portion 30 has a sensor unit 31 and a converter unit 32 housed and fixed in two semi-cylindrical sensor cases 34. It is. The sensor case 34 has a diameter of 4
It is made of a vinyl chloride pipe of 0 to 50 mm or the like.
A sensor storage section 35 and a converter storage section 36 which are partitioned by two wall sections 37 are formed. This sensor storage unit 35
The sensor unit 31 having a low columnar shape includes a horizontal storage portion 44 for setting the sensor unit 31 horizontally in the axial direction and a vertical storage portion 43 for setting the sensor unit 31 vertically in the axial direction.

As shown in FIG. 6B, the internal structure of the sensor unit 31 is such that a disk-shaped target 46 made of iron, copper, or the like is made of beryllium copper or the like in a cylindrical sensor housing 45 having a small height. The sensor 48 is mounted so as to float in the air, and a probe 48 is provided on one surface of the sensor housing 45 so as to face the target 46 at a predetermined distance D. This probe 4
As shown in FIG. 6A, a coil 8 mainly includes a coil 49, and a capacitor 50 and an oscillation circuit 51 are connected to the other end.

In order to perform measurement by burying the underground displacement meter 28 vertically as shown in FIG. 1 (a), if the sensor unit 31 is to be sensitive to front, rear, left and right inclinations, Then, the sensor unit 31 is housed in the vertical housing 43 as shown in FIG. 4B (a direction orthogonal to the length direction of the sensor rod 30). Then, the converter unit 32 is stored in the converter storage section 36, and the cable 33 is
2, the mold 62 is packed in the gap between the sensor housing 35 and the converter housing 36 to fit the two sensor cases 34 together. At this time, one sensor case 3
The positioning projection 39 of 4 is positioned by fitting into the other positioning hole 40, and then a screw 61 is inserted into the connecting screw hole 41 to be integrally fixed.

If the sensor unit 31 is to be sensitive to vertical inclination in order to perform the measurement by burying the underground displacement meter 28 horizontally, the sensor unit 31 is connected to the sensor unit 31 as shown in FIG. ) Is stored in the horizontal storage portion 44 (in the same direction as the length direction of the sensor rod portion 30).

The sensor rod 30 constructed as described above
The small diameter portion 38 for connection is fitted to the end of the connecting rod portion 29 and fixedly connected by welding or with an adhesive 60 to form the underground displacement meter 28 of about 1 m in length. You. Underground displacement gauges 28 having such a unit length are connected to several to several tens according to the purpose, and even longer if necessary.

The underground displacement meter 28 constructed as described above
Is inserted into a vertical boring hole 63 as shown in FIG. When a landslide occurs and is bent and inclined by the landslide mass 11 as shown in FIG. 1B, the inclined sensor unit 31 detects and outputs the angle.

The principle of measuring the tilt angle of the sensor unit 31 will be described with reference to FIG. When an oscillation circuit 51 of several MHz is connected to the coil 49 of the probe 48,
When the distance D between the target 9 and the target 46 is short, the target 46
An eddy current is generated. When the distance D is further reduced and the supply of energy from the coil 49 increases, the probe 4
The oscillation voltage rises as the transmission voltage of No. 8 decreases and, on the contrary, increases.

Here, when the sensor unit 31 is inclined, the target 4 suspended by the spring 47 is moved.
Since 6 moves in the inclined direction, the distance D from the probe 48 changes. Since a correlation is obtained between the change in the distance D and the oscillation voltage of the probe 48, a signal having a correlation with the distance D is output from the probe 48. The output of the sensor unit 31 is input to the converter unit 32 shown in FIG. 5, detected by the detection circuit 52, amplified by the signal amplification circuit 53, and outputted from the voltage output circuit 54 to the signal output terminal 58. The power supply in the converter unit 32 is a power supply 5
9 through a noise canceller 55 and a stabilizing power supply 56 to remove noise and supply a stabilized voltage. Since the oscillation voltage of the sensor unit 31 and the distance D have a non-linear relationship, they are corrected by the linearization circuit so as to have a proportional relationship. In FIG. 5, 57
Is a shield case.

Next, the operation of the sensor unit 31 as the underground displacement meter 28 will be described with reference to FIG.
In FIG. 1 (c), the underground displacement meter 28 immediately after installation is in a vertical state as shown in FIG. 1 (a), and the inclined underground displacement meter 28 is indicated by a circle in FIG. 1 (b). This is the state after the change enclosed. In FIG. 1 (c), L1 is an underground displacement meter 2
8, An is the amount of variation, θn is the inclination angle, L2 is the length of the hypotenuse, and if L1 ≒ L2, then An = L2tan
θn. The relative displacement d in the boring hole 63 can be obtained by accumulating this An by the following equation.

Next, specific test results will be described below. (1) Specimen The underground displacement meter 28 used in the test has a connecting rod 29 and a sensor rod 30 made of a PVC pipe having an inner diameter of 40 mm and a length of 1 m, in which a sensor unit 31 and a converter unit are provided. 32 are stored as one unit length, and eight units (8 m) are connected linearly with the adhesive 60. In this case, as shown in FIG. 4B, the sensor unit 31 is attached so as to have sensitivity in the front, rear, left and right directions.

(2) Test method An 8 m underground displacement meter 28 is inserted into a vertical boring hole 63, and the upper and lower ends are fixedly attached. Is measured. That is, the case where the upper and lower ends of the underground displacement meter 28 do not have a landslide but have a landslide at the center is measured. The amount of deformation of the pipe is measured by measuring the distance between the pipe and a reference line perpendicular to the measurement points provided at 0.5 m intervals on the test piece and bending the pipe in a bow shape, and plotting the displacement state of the test piece. Further, the sensor output value in each displacement state is measured by the sensor unit 31 and sent to the converter unit 32 to calculate the displacement amount of the test object. The displacement amount at the point of action was sequentially displaced every 100 mm to 100 mm. The following three types of measurement directions (sensitivity directions) of the underground displacement meter 28 were used as shown in FIGS. 7A, 7B, and 7C. In FIG. 7, the double-lined arrow indicates the displacement direction, and the single-lined arrow indicates the sensitivity direction of the sensor unit 31. Test 1: As shown in FIG.
1 in the direction parallel to the sensitivity direction. Test 2: As shown in FIG.
1 in the direction parallel to the sensitivity direction. Test 3: As shown in FIG.
1 in the direction perpendicular to the sensitivity direction.

(3) Test Equipment All the signal output terminals 58 from the sensor rod 30 attached to the eight underground displacement meters 28 are input to a recorder (not shown), and the sensor output values are output. Measure.

(4) Test Results Test 1: 0 every 10 mm in the same direction as the measurement direction line
The approximate center of the eight underground displacement meters 28 is displaced to 100 mm. The test results are as shown in FIG. Test 2: 0 every 10 mm in the direction opposite to the measurement direction line
The approximate center of the eight underground displacement meters 28 is displaced to 100 mm. The test results are as shown in FIG. Test 3: The center of eight underground displacement meters 28 is displaced from 0 to 100 mm every 10 mm by shifting the measurement direction line by 90 degrees. The test results are as shown in FIG.

(5) Data Analysis Based on the test results, the actual displacement amount of the PVC pipe is compared with the measured amount of the sensor rod 30, and errors and installation and construction characteristics are grasped. Analysis: The voltage output value from the underground displacement meter 28 is calculated from the relative displacement angle from the initial state and the displacement amount of the pipe,
By accumulating this, the displacement amount of the pipe is calculated. The state of FIG. 1A in which the underground displacement meter 28 is installed vertically is defined as an initial state. Based on this state, a difference when a displacement is applied to the test body is obtained. FIG. 6C shows a state where a displacement is applied to the test body. At this time, assuming that the length of the lowermost underground displacement meter 28 is L1, the variation is A1, and the inclination angle is θ1, A1 can be approximately obtained by the following equation (1). A1 ≒ 1000 × tan θ1 (1) In this embodiment, eight PVC pipes L1, L2, L3,.
Variations A1, A2, A3,... A8 at each side point of L8
Is calculated using the above equation (1). The relative variation An at each side point of the PVC pipe was determined by the following equation (2). In the example as shown in FIG. 6C, the relative displacement d can be obtained as d = A1 + A2 + A3. Results 5. Based on the test results. The relative displacement of the test specimen was determined using the method described in (1). The calculation results are as shown in FIGS. 8, 9, and 10. From the results of these tests 1 and 2, it can be seen that the fluctuation amount of the test specimen by actual measurement and the fluctuation amount (calculated value) of the test specimen due to the sensor output value are very similar. As a result, it is understood that the displacement shape (unit inclination length) can be grasped by measuring the displacement amount (inclination angle) using the underground measurement device according to the present invention. In Test 3, it can be seen that the amount of displacement cannot be captured for the change in the direction perpendicular to the sensor sensitivity direction.

[0027]

【The invention's effect】

(1) The present invention includes the sensor unit 31 for detecting an angle from a change in the gap due to the inclination and the converter unit 32 for converting the detection signal into an electric signal, so that many measurement points can be measured in real time. Further, measurement can be performed in both the horizontal direction and the vertical direction by simply changing the direction of the sensor unit 31. In addition, the length in the longitudinal direction can be made extremely small, and the conventional differential transformer system has a pendulum type structure, thereby solving the problem of difficulty in downscaling in the longitudinal direction.

(2) According to the present invention, when the sensor unit 31 is inclined, the target 46 suspended by the spring 47 moves in the inclined direction, and the distance D from the probe 48 changes. And the oscillation voltage of the probe 48, a correct output signal having a correlation with the distance D is output from the probe 48. In addition, the sensitivity can have directivity. Accordingly, the calculation of the angle is simple, and the configuration of the underground displacement meter 28 can be made robust, which is favorable for detecting the underground displacement.

[Brief description of the drawings]

FIG. 1 illustrates the basic operation of an underground displacement measuring device according to the present invention.
3 is an explanatory diagram in which an underground displacement gauge 28 is inserted by drilling 3
(B) is an explanatory view of a state in which a part of the underground displacement meter 28 is inclined by the landslide mass 11, and (c) is an explanatory view of calculation of an inclination angle.

FIG. 2 is an exploded perspective view of a sensor rod 30 according to the present invention.

FIG. 3 is an exploded perspective view showing an example in which a sensor unit 31 in FIG. 2 is mounted with a mounting angle shifted by 90 degrees.

4A is a cross-sectional view of a state where the sensor unit 31 is attached to the state of FIG. 2 and assembled, and FIG. 4B is a cross-sectional view of a state where the sensor unit 31 is attached and assembled to the state of FIG. is there.

FIG. 5 is a block diagram of a converter unit 32 according to the present invention.

6A is an explanatory view of the principle of the sensor unit 31, FIG. 6B is a cross-sectional view of the sensor unit 31, and FIG.
FIG. 8 is an explanatory diagram of a calculation when the underground displacement meter 28 is displaced.

7A is an explanatory diagram of test 1 (in the case where the sensitivity direction of the sensor unit 31 is parallel to the measurement direction line), and FIG. 7B is a diagram illustrating test 2 (the sensitivity direction of the sensor unit 31). (C) is an explanatory diagram of test 3 (a case perpendicular to the sensitivity direction of the sensor unit 31).

FIG. 8 is a graph showing measurement results of Test 1.

FIG. 9 is a graph of a measurement result of Test 2.

FIG. 10 is a graph showing measurement results of Test 3.

11 (a) is an explanatory view of digging a vertical boring hole at a measurement point and examining displacement / deformation in the hole with a rod-shaped inclinometer 12, and FIG. 11 (b) shows a horizontal boring hole. It is an explanatory view in the case of excavating and examining displacement / deformation in the hole with a rod-shaped inclinometer 12.

FIG. 12A is an explanatory diagram of a measuring method using a conventional differential transformer system, and FIG. 12B is an explanatory diagram of the principle of a differential transformer.

FIG. 13A is an explanatory diagram of a measuring method using a conventional strain gauge system, and FIG. 13B is an explanatory diagram of the principle of a strain gauge.

[Explanation of symbols]

10: ground mountain, 11: landslide mass, 12: inclinometer, 13
... embankment, 14 ... weight, 15 ... hanging string, 16 ... pendulum, 17
... iron core, 18 ... primary coil, 19 ... secondary coil, 20 ...
Driving oscillator, 21 ... Differential transformer, 22 ... Output transformer, 23 ... Pipe, 24 ... X direction strain gauge, 25 ... Y
Directional strain gauge, 26 ... Input terminal, 27 ... Bridge circuit, 28 ... Underground displacement meter, 29 ... Connecting rod, 30 ... Sensor rod, 31 ... Sensor unit, 32 ... Transducer unit
33 ... Cable, 34 ... Sensor Case, 35 ... Sensor Storage Section, 36 ... Converter Storage Section, 37 ... Wall Section, 38 ... Connecting Small Diameter Section, 39 ... Alignment Protrusion, 40 ... Alignment Hole,
41 ... connecting screw hole, 42 ... cable hole, 43 ... vertical storage part, 44 ... horizontal storage part, 45 ... sensor housing, 46
... Target, 47 ... Spring, 48 ... Probe, 4
9: coil, 50: capacitor, 51: oscillation circuit, 52
Detector circuit 53 Signal amplifier circuit 54 Voltage output circuit 55 Noise canceller 56 Stabilized power supply 5
7 Shield case, 58 Signal output terminal, 59 Power supply, 60 Adhesive, 61 Screw, 62 Mold, 63
... boring holes.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ken Okada 624-1 Shinyoshida-cho, Kohoku-ku, Yokohama-shi, Kanagawa Lumiere A-101 (72) Inventor Tohru Tomonari 4-48-17 Honcho, Nakano-ku, Tokyo Stock Company electronic applications

Claims (5)

[Claims] 1. An underground displacement measuring device in which a boring hole 63 is drilled at an underground displacement measuring point and an underground displacement meter 28 is inserted to obtain an underground displacement.
Is formed by connecting the connecting rod portion 29 and the sensor rod portion 30,
The sensor rod portion 30 includes a sensor unit 31 that detects an angle from a change in a gap due to an inclination, and a converter unit 32 that converts a detection signal of the sensor unit 31 into an electric signal. Underground displacement measurement device. 2. An underground displacement meter 28 is formed by connecting a connecting rod portion 29 and a sensor rod portion 30 to form an underground displacement meter 28 having a unit length. The underground displacement measuring device according to claim 1, wherein the underground displacement measuring device is connected in a permanent manner. The sensor unit 31 includes a conductor 47 and a spring 47 in a sensor housing 45.
And a probe 48 is provided on one surface of the sensor housing 45 so as to face the target 46 at a fixed distance.
9, a high-frequency oscillation circuit 51 is connected to
2. An underground displacement measuring apparatus according to claim 1, wherein an eddy current is generated in the sub-surface, and a distance is calculated from a change in the oscillation voltage of the probe to obtain an inclination angle. 4. The sensor unit 31 includes an underground displacement meter 28.
When the sensor unit 31 is embedded vertically and has sensitivity to the front-back, left-right inclination, the sensor unit 31 is
The underground displacement measuring device according to claim 1, wherein the underground displacement measuring device is housed in a direction orthogonal to a length direction of the underground. 5. The sensor unit 31 includes an underground displacement meter 28.
The sensor unit 31 is housed in the same direction as the length direction of the sensor rod portion 30 when the sensor unit 31 is embedded horizontally and has sensitivity to vertical inclination. Underground displacement measuring device.