JP2001050781A - Disturbed state measuring device for ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor and measure the disturbed state of the ground even when the direction of disturbed state is known and the disturbed state quantity is minimum, and even when the direction of disturbed state is unknown and the quantity is maximum, by providing a groove for fixing core wire on one face of a member stuck with a flexible optical fiber core wire in one specific direction. SOLUTION: A member 20 is fundamentally provided with rigidity, provided with flexibility only in one direction, and a groove 22 for sticking an optical fiber core wire 30 on the opposite side of a irregular part 21. The member 20 is provided so that the irregular part 21 side of arranged dales and hills is stuck to the disturbed state generated place of the ground or the like. When the direction of the disturbed ground is known, a strain-loss joint type optical pulse tester is connected to one end of the optical fiber core wire, strain of the optical fiber core wire 30 accompanying the disturbed state of ground is measured, and diplacement generating it is obtained to compute the disturbed state of ground. When the direction of the ground disturbed state is unknown, a plurality of the members 20 are combined to be provided in the respective directions, the disturbed states in the respective directions are measured, these strains are vector-compounded, and the disturbed state quantity and the direction of the measured point can be computed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a deformation of an object to be measured by detecting a distortion of an optical fiber core attached to the object to be measured.

[0002]

2. Description of the Related Art When measuring deformation such as distortion of a structure or ground, a method of converting distortion into electric resistance using a strain gauge or the like has been conventionally used. According to this conventional method, it is possible to accurately measure the deformation in the vicinity of several mm to several cm to which the strain gauge is attached. However, in the above conventional example,
There is a drawback that it is difficult to measure the deformation over a long distance.

[0003] Conventionally, ground deformation has been measured by visual observation of cracks and the like, and by using inclinometers, sinkers, displacement meters, and load meters. However, measuring in this way requires a lot of trouble because it is necessary to perform observations periodically, and the measurement points become discontinuous points.
The disadvantage is that it is difficult to monitor and measure large-scale structures and deformations in a wide area.

Further, when the amount of deformation is large, such as in an earthquake, surveying by aerial photography is performed before or after the earthquake, or the deformation is actually measured. However, such a measurement requires a great deal of time and labor, and has a drawback that it is difficult to measure the data during or immediately after the earthquake.

On the other hand, as a method for easily measuring a deformation over a long distance, a method for measuring the deformation using an optical fiber is known. This method is a method of measuring deformation by bonding an optical fiber to a deformed object, and the frequency distribution related to the intensity of Brillouin scattered light in the longitudinal direction of the optical fiber shifts according to the size of the deformation. This is a method of measuring the deformation over a long distance. In this measurement method, a measurement light pulse is incident on an optical fiber bonded and fixed to a deformed object, and the measurement position can be determined based on the time until the scattered light generated in the optical fiber is received. In addition, by analyzing the frequency distribution of the intensity of the scattered light, it is possible to determine the deformation at the measurement position.

[0006]

The conventional technique for measuring the deformation using the optical fiber can obtain a wide range of data as information on a line along the optical fiber.

However, the above-described conventional technique of measuring deformation using an optical fiber does not take into account the vertical distribution of ground deformation and the exact direction of large deformation or deformation.

According to the present invention, it is possible to perform high-precision monitoring and measurement when the deformation direction is known but the amount of deformation is small, assuming deformation of the ground due to observation construction and proximity construction. Moreover, assuming the ground deformation due to the liquefaction phenomenon during an earthquake, the direction of the deformation is unknown, but when the deformation amount is large, the ground direction and the large deformation amount can be detected. It is an object of the present invention to provide a ground deformation measuring device for monitoring and measuring the ground.

[0009]

According to the present invention, there is provided an apparatus for measuring a deformation of an object to be measured by detecting a distortion of an optical fiber core deforming together with the object to be measured.
A member having flexibility in only one predetermined direction, a member to which the optical fiber core is attached, and a groove for fixing the optical fiber core provided on one surface of the member. It is a deformation measuring device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a ground deformation measuring apparatus 10 according to a first embodiment of the present invention.

The ground deformation measuring apparatus 10 is a member 20 for measuring ground deformation, and an optical fiber core 30 is attached to the member 20.

The member 20 has a plate-like shape, and its one surface (surface) is provided with irregularities 21 on which peaks and valleys are aligned.
Having. That is, the heights of the plurality of peaks in the unevenness 21 are the same, and the depths of the plurality of valleys in the unevenness 21 are the same. Note that a rod-shaped or film-shaped member may be used as the member 20 instead of the plate-shaped member.

The member 20 is basically a member having rigidity, but has flexibility only in one direction. In other words, in the direction of the ridgeline of the mountain (direction B) in the unevenness 21 of the member 20,
Although it has great rigidity, it has flexibility in the direction (A direction) orthogonal to the ridgeline of the mountain in the member 20 because the rigidity is reduced by the valley.

The member 20 has a groove 22 for attaching an optical fiber 30 on the surface (back surface) opposite to the unevenness 21. The optical fiber 30 is reciprocated about several times in the groove 22, and the optical fiber 30 is integrated with the member 20.

Next, the operation of the ground deformation measuring apparatus 10 according to the above embodiment will be described.

First, the concave-convex 21 side of the member 20 to which the optical fiber core 30 is attached is arranged in close contact with a place where deformation occurs such as the ground.

At one end of the optical fiber core 30,
A conventional distortion / loss integrated optical pulse tester (not shown)
TDR) is connected, and measures the distortion of the optical fiber core wire 30 accompanying the deformation of the ground, and calculates the amount of deformation of the ground by calculating the displacement causing the distortion.

In the direction of the ridgeline (direction B) of the ridges and projections 21 of the member 20, there is little distortion due to high rigidity, and the rigidity is low (direction perpendicular to the ridgeline direction of the mountain, direction A). Distortion occurs. Therefore, the member 20
By using the optical fiber core 30 stuck on the ridge, it is possible to detect only the distortion in the direction (A direction) perpendicular to the ridgeline direction of the mountain.

The above embodiment is used when the direction of the ground deformation is known and the amount of deformation in the direction of the ground deformation is calculated.

As the rigidity of the member 20 itself, a rigidity suitable for the rigidity of the ground to be measured is selected. As the member 20, for example, hard vinyl or hard rubber is used.

FIG. 2 is a view showing a ground deformation measuring apparatus 11 according to a second embodiment of the present invention.

FIG. 3 is a view showing a ground deformation measuring apparatus 12 according to a third embodiment of the present invention.

FIG. 4 is a view showing a ground deformation measuring apparatus 13 according to a fourth embodiment of the present invention.

The ground deformation measuring devices 11, 12, and 13
It is an example of arrangement of the member 20 when the direction of the ground deformation is unknown.

When the direction of the ground deformation is unknown, the deformation of the ground in each direction can be measured by installing a plurality of members 20 as shown in FIGS. . In this case, the distortion obtained by projecting the ground deformation in a direction perpendicular to each member 20 is measured by each optical fiber core 30. Also, by combining the distortion as a vector, the magnitude and direction of the deformation at the measurement point can be calculated.

The torsion of the member 20 can be grasped from the state of distribution of the strain of the member 20 measured by the optical fiber 30 stuck back and forth.

Particularly, when monitoring and measuring the deformation of the ground due to the liquefaction phenomenon during an earthquake, the deformation range of the ground becomes large, and it becomes difficult to calculate the absolute displacement. It is desirable to embed and use until a depth without displacement is reached.

In the above embodiment, the flexible member 2
Since 0 is used, the ground followability is improved, and the deformation of the ground can be accurately measured.

Further, in the above embodiment, the unevenness 2
By causing the member 20 having 1 to follow the movement of the ground, the distortion of the member 20 can be limited to one direction, so that only the deformation in a specific direction can be measured.

Further, by using a plurality of members 20 in combination and combining the observed deformations as vectors, the direction of the deformation can be measured with high accuracy.

Furthermore, by twisting the optical fiber core 30 back and forth on the member 20 several times, the twisted state of the member 20 can be grasped. In other words, as described above, the deformation of the member 20 is restricted so as to occur only in one direction. However, it is expected that the twist may still occur depending on the direction of deformation of the ground. A large difference occurs in the measured values at both ends of the core wire 30, and by detecting this difference, the torsion state of the member 20 can be grasped.

Further, in the above-described embodiment, it is possible to eliminate the directional deformation error. That is, since the projections and depressions 21 are provided on the surface of the member 20, the strain generated in the member 20 is limited to one direction. The value of only the strain measured at the central portion of the optical fiber core 30 that has been reciprocated and adhered is used.

In the above embodiment, the cross-sectional shape of the unevenness 21 is triangular, but a polygon such as a rectangle may be used instead of a triangle, or a semicircle may be used.

The member 20 in the above embodiment has irregularities 21 in which peaks and valleys are aligned.
Instead, a member having irregularities that are regularly repeated in one predetermined direction may be used. That is, the member 20 has flexibility only in one predetermined direction,
It is an example of a member to which an optical fiber is attached.

Instead of the member 20, for example, a flexible flat plate or the like in which metal rods are embedded in parallel at equal intervals may be used. Even if you do this,
Flexibility can be provided in only one direction.

[0036]

According to the present invention, high-precision monitoring / measurement is performed when the deformation direction is known but the deformation amount is small, assuming the ground deformation due to the observation construction and the proximity construction. In addition, assuming the ground deformation due to the liquefaction phenomenon during the earthquake, if the deformation direction is unknown but the deformation amount is large, the deformation direction and large deformation amount are detected. It has the effect of being able to do so.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a ground deformation measuring apparatus 10 according to a first embodiment of the present invention.

FIG. 2 is a view showing a ground deformation measuring apparatus 11 according to a second embodiment of the present invention.

FIG. 3 is a view showing a ground deformation measuring apparatus 12 according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a ground deformation measuring apparatus 13 according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10, 11, 12, 13 ... ground deformation measuring device, 20 ... member, 21 ... unevenness, 22 ... groove, 30 ... optical fiber core.

Continuation of front page (72) Inventor Hiroshi Komatsu 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2F065 AA65 CC00 CC40 DD00 FF12 FF33 LL02 PP01 UU03 2F076 BA01 BA11 BB09 BD05 BD06 BD17 BE02 2G086 CC03 DD05

Claims (8)

[Claims] An apparatus for measuring a deformation of an object to be measured by detecting a distortion of an optical fiber core deformed together with the object to be measured, wherein the apparatus has flexibility only in one predetermined direction, A ground deformation measuring apparatus comprising: a member to which the optical fiber core is attached; and a groove for fixing the optical fiber core provided on one surface of the member. 2. The ground deformation according to claim 1, wherein the member is provided with irregularities that are regularly repeated in one predetermined direction on a surface opposite to the one surface. Condition measuring device. 3. The ground deformation measuring apparatus according to claim 2, wherein the irregularities are irregularities in which peaks and valleys are aligned. 4. The ground deformation measuring apparatus according to claim 2, wherein the unevenness has a polygonal or semicircular cross-sectional shape. 5. The ground deformation measuring apparatus according to claim 1, wherein the member is at least one member of a plate shape, a rod shape, and a film shape. 6. The ground deformation measuring apparatus according to claim 1, wherein the fixing groove of the optical fiber is a groove that reciprocates continuously. 7. The ground deformation measuring device according to claim 1, wherein a plurality of ground deformation measuring devices are provided, and a T-shaped or L-shaped shape is determined by the plurality of ground deformation measuring devices. A ground deformation measuring device characterized by being formed. 8. The deformation of a ground according to claim 7, wherein a direction of the deformation is measured by synthesizing a deformation measured by each of the plurality of ground deformation measuring devices as a vector. Condition measuring device.