JPS63120210A - Apparatus for measuring deformation of pipe - Google Patents

Abstract

PURPOSE:To obtain an accurate measured value without receiving the effect of the material quality of a pipe to be measured and earth magnetism, by a method wherein a measuring rod having a leaf spring part having strain gauges adhered to the front and back surfaces thereof is inserted in an underground embedded pipe in parallel to the axis of said pipe when the deformation of the embedded pipe is measured and the deformation of the embedded pipe is measured on the basis of the outputs of the strain gauges. CONSTITUTION:Four symmetric grooves 12 are usually provided on the inner wall surface of a boring hole or the pipe 10 to be measured arranged in the ground and a measuring rod 14 made of a rigid material having rod-shaped centralizers 16 inserted in the grooves 12 protruded therefrom is inserted in the pipe 10 to be measured in parallel to the axis thereof by utilizing said grooves 12. At this time, two rods 14 are prepared and a deformation detection part 18 is fixed between said rods 14. Horizontal and vertical leaf spring parts 22, 24 are provided on both sides of the central connection part 26 of the detection part 18 so as to hold said connection part 26 therebetween, and bending detecting strain gauges 30a and distortion detecting strain gauges 30b, 30c symmetric to the center axis of the pie 10 to be measured at 45 deg. are respectively adhered to the front and back surfaces of said leaf spring parts 22, 24 and the outer periphery of the detection part 18 is covered with a flexible protective pipe 28. By this method, a structure is made simple and the operation is facilitated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for measuring large bends in poling holes, deformation of underground pipes, etc. The deformation of the pipe to be measured can be measured by connecting the rod with a bendable temporary spring part and inserting it into the pipe to be measured, and measuring the amount of deformation with strain gauges attached to the front and back surfaces of the plate spring part. This relates to a device that has been used.

[Prior Art] Conventionally, inclinometers have been widely used to measure the surface roughness of poling holes, deformation of underground pipes, and the like. In this type of instrument, inclination in the vertical plane is accurately measured using gravity using servo accelerometers and potentiometers, but these cannot be used to measure displacement in the horizontal direction, and fluxgate type magnetic flux is used to measure displacement in the horizontal direction. A geomagnetic sensor such as a geomagnetic sensor is used.

Deformation of the pipe to be measured can be measured by inserting an inclinometer from the mouth end and measuring the amount of inclination for each insertion amount (insertion measurement method), or by accommodating a large number of inclinometers in a string and measuring the inclination at each part. This is done by measuring the amount of inclination (fixed measurement method).

[Means for solving the problem] Therefore, if the pipe to be measured is an iron pipe buried horizontally, the orientation (horizontal displacement) cannot be measured, and even if the pipe to be measured is made of non-magnetic material. Even if the geomagnetic field is made up of , the direction cannot be determined if there is magnetic material buried nearby or if there is disturbance in the geomagnetic field. There are other azimuth measuring devices such as gyro compasses, but they are quite large and cannot be used with thin tubes, and they also have the disadvantage of poor accuracy.

Furthermore, in measurements using conventional inclinometers, a gauging tube with a predetermined groove formed in it is used as the tube to be measured, and the wheels of the measurement probe are fitted into the groove and inserted along the groove, resulting in the casing being twisted. In some cases, the torsion cannot be measured, resulting in a measurement error, and the wheel often derails from the groove, resulting in an even larger measurement error.
There are also problems such as having to repeat measurement work many times.

In addition, the outer circumference of the PVC pipe is divided into two or four equal parts, and strain gauges are pasted on the axial extension line at intervals of 1 to 2 m, and the holes are buried in the poling holes to measure the hole surface roughness. Some pipes have strain gauges attached to them, but they can only be used to roughly measure the shape of deformation in ground water, and are not suitable for measuring deformation in a strict sense.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to be able to handle tubes to be measured of any material and shape, and to prevent bending, twisting, etc. of the tube even when the tube is arranged horizontally. It is an object of the present invention to provide a device that makes it possible to easily measure the deformation of a pipe to be measured, including the deformation of the pipe to be measured, easily and accurately at low cost.

[Means for Solving the Problems] The present invention, which can achieve the objects as described in L, has a structure in which a plurality of measuring rods made of a novel material are connected via a bendable deformation detection part. This is a pipe deformation measuring device.

Here, each measuring rod is equipped with a positioning mechanism such as a centrifuge that maintains a constant position within the tube to be measured in a plane perpendicular to its axis. In addition, the deformation detection section has a measurement port and a bendable plate spring section that connects the dots. be.

A more desirable embodiment is a configuration in which two leaf spring parts are arranged perpendicular to each other and shifted in the axial direction, and a plurality of strain gauges are attached to the front and back surfaces of the leaf spring parts in the axial direction and in a direction inclined with respect to the axis. .

[Operation] The measuring rods located on both sides of the deformation detecting section are kept at a constant position in a plane perpendicular to the central axis within the tube to be measured by their respective positioning mechanisms. If the tube to be measured is deformed, such as by bending, the deformation appears as deformation of the leaf spring section. The temporary spring part is equipped with strain gauges on both the front and back sides.
Deformation of the leaf spring section is detected by a strain gauge.

That is, deformation of the tube to be measured can be detected from the outside by the output of the strain gauge.

If two plate spring sections are connected orthogonally to each other and installed, bending in two axes can be detected, and by changing the angle at which the strain gauge is attached to the temporary spring section, twisting of the tube to be measured can be detected. can be detected.

[Example] FIG. 1 is an explanatory view showing an example of a pipe deformation measuring device according to the present invention, and FIG. 2 is a ll-Tl sectional view thereof.

This embodiment measures the deformation of a pipe to be measured lO buried horizontally in the soil, and is an insertion type measuring device.

The pipe to be measured 10 is buried in the soil, and its cross section is
As is clear from the figure, the conventional technique has a structure in which four grooves 12 are formed symmetrically at 1190 degrees. Now, this device has two measuring rods 14 made of a rigid material,
Each measuring rod 14 is equipped with a centrifuge 16 as a positioning device that maintains a constant position within the tube 10 to be measured in a plane perpendicular to its axis. The centrifuge 16 is fitted into the tube a 12 of the tube to be measured 10, and constantly holds the measuring rod 14 with respect to the central axis while preventing rotation about the axis.

The remeasurement rods 14 are connected by a deformation detection section 18, and an insertion rod 20 is connected to the end of one of the measurement rods 16.
is attached so that it can be pushed in from the open end side and moved freely within the tube to be measured.

Now, an example of the deformation detection section according to the present invention is shown in FIGS. 3 to 5. In this embodiment, the deformation detection section 18 has two leaf spring sections 22, 24 and a connecting section 26. The two leaf spring parts 22 and 24 are both arranged on the central axis and have a bendable structure, and as is clear from the cross-sectional views of Figs. 4 and 5, they are arranged in directions 90 degrees different from each other. They are arranged at different axial positions. And these leaf spring parts 22
．． 24 is the connecting part 26 in the center and the measurement throats 14 on both sides.
are connected by a flexible protection tube 28 on the outside.
sealed. It is desirable that the flexible protection tube 28 has a structure in which, for example, piano wire is arranged in a spiral shape and buried inside rubber, so that it will not be crushed by bending or chamfering.

A large number of strain gauges 30 are attached to the same positions on both the front and back surfaces of the leaf spring section 22. This embodiment consists of a bending detection strain gauge 30a arranged along the central axis, and torsion detection strain gauges 30b and 30C mounted symmetrically at 45 degrees with respect to the central axis. Leaf spring part 2
4 also has strain gauges 30 arranged in exactly the same way.

These strain gauges may be attached to the front and back surfaces of the leaf spring section with an adhesive or the like, or the strain gauges may be formed directly on the front surface of the temporary spring section using vacuum deposition or sputtering techniques. In particular, with such a thin film structure, since no adhesive is used, there is no creep and high performance with excellent long-term stability can be achieved.

In either case, a strain gauge disposed on the central axis detects bending of the leaf spring, and strain gauges mounted at angles in two directions with respect to the central axis detect twisting of the leaf spring.

In this embodiment, each measuring loft is depicted as having a solid structure, but it is preferable to have a hollow structure with a built-in strain gauge preamplifier or a structure through which a cable is passed.

Now, the operation of this apparatus configured as described above and the procedure for its use are as follows. In Fig. 1, the insertion rod 2
The measuring rod 14 is pushed into the tube to be measured 10 from the open end using the centrifuge 16 of the tube to be measured 10. Get stuck in 12 and follow it! Move without lJJ.

Both: The rod 14 for fixing the rod 14 is configured so that it can be relatively displaced and directed via the deformation detection section 18, so it always remains located at its central axis J2 following the deformation of the tube to be measured IO. . Therefore, if the tube to be measured 10 is deformed such as bending or twisting due to deformation of the ground, the deformation appears as a deformation of the leaf spring portions 22, 24 of the deformation detection section 18.

As described above, the strain gauge disposed on the central axis detects the bending of the leaf spring portion. Since each strain gauge is provided in pairs on both the front and back surfaces of the temporary spring section, accurate measurements can be made by differentially amplifying the outputs of the corresponding strain gauges. Further, strain gauges attached at 45 degrees in two directions with respect to the central axis detect the torsion of the leaf spring.

In the case of torsion, one strain gauge (for example 30b) expands and the other strain gauge (in this case 300) located symmetrically with it contracts, so that the magnitude and direction can be detected by them.

Therefore, by detecting the bending of one leaf spring section 22 (shown in FIG. 4) with a strain gauge placed in the center, the bending in the horizontal direction can be measured, and the bending of the other temporary spring section 24 (shown in FIG. 5) can be measured. Vertical bending can be measured by detecting the bending with a strain gauge also placed in the center.

The torsion of the tube 10 to be measured can be measured by strain gauges located on both sides of each leaf spring section. In this way, the measuring rod 2
By continuing the measurement while changing the measurement point based on 0, the deformation of the tube to be measured IO can be determined accurately.

FIG. 6 shows another embodiment of the present invention, and is an example of a fixed measurement method. This is a configuration in which a deformation detecting section 1B is inserted between a large number of measuring rods 14 in the tube 10 to be measured, and the amount of deformation of each deformed section is measured. Since each part of the apparatus may be basically the same as in the above embodiment, corresponding parts are given the same reference numerals and detailed explanation thereof will be omitted.

Although preferred embodiments of the present invention have been described in detail above, it is important to note that the present invention is not limited to only such configurations. If it is necessary to detect bending in only one direction, only one temporary spring part may be used. Therefore, a measuring device can be constructed in combination with a conventional inclinometer or the like. In addition, (if there is no need to detect return), the strain gauge may have a structure in which a pair of front and back sides are provided in the central axis direction for each leaf spring part, and the tube to be measured does not have to have a grooved structure. It can also be applied to measuring deformation of buried pipes, etc.

The positioning mechanism attached to the measuring rod may be a spring-type centrifuge or a wheel system, and in some cases, the measuring rod may be pressed against one wall using a spring or the like to keep it in a fixed position. can.

[Effects of the Invention] As described above, the present invention has a structure in which a plurality of measurement rods each having a positioning mechanism and made of an open material are connected via a temporary spring portion having a strain gauge, so that the influence of the material of the pipe to be measured can be avoided. It is also possible to measure inside iron pipes without being affected by geomagnetism, so it has the effect of easily measuring bends in existing horizontal pipes, etc.

Furthermore, in the present invention, since the measuring rod is connected via a bendable leaf spring part, even if the casing is twisted, it is possible to measure the torsion including that twist, which may increase the measurement error of bending. In addition, it has an N-unit structure, can be manufactured at low cost, and has excellent effects such as ease of operation.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of the pipe deformation measuring device according to the present invention, Fig. 2 is a sectional view taken along line nn, and Fig. 3 is a detailed view of the deformation detecting section of the pipe deformation measuring device according to the present invention. An explanatory diagram showing an example, FIG. 4 is a cross-sectional view of the IV-rV, and FIG.
-V sectional view and FIG. 6 are explanatory diagrams showing another usage state of the device according to the present invention. 10...Measurement tube, 14...Measurement rod, 16.
・・Centralizer, 1B・・・Deformation detection part, 22゜2
4...Temporary spring part, 30...Strain gauge. Patent Applicant: Yoyoi Geology Co., Ltd. Director Shigemi Minoru 6i
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Claims (1)

[Claims] 1. A plurality of measurement rods made of a rigid material are equipped with a positioning mechanism that maintains a constant position in a plane perpendicular to the axis within the pipe to be measured, and are placed in parallel to the axis via a bendable leaf spring section. A pipe deformation measuring device characterized in that the plate spring portion is connected to each other and strain gauges are provided on both the front and back surfaces of the plate spring portion.