JP2001074514A - Distortion detecting apparatus for ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect ground distortion in any direction, to execute work without a preliminary survey of distortion direction with respect to the ground for an installation field, and to execute work and detect distortion even for the ground having unpredictable distortion direction. SOLUTION: A distortion-detecting outer pipe 1 capable of being bent in any direction by distortion in the ground 2 is embedded in a depth direction in the ground 2. A distortion-detecting inner pipe 9 capable of being axially bent in any direction is disposed inside the distortion-detecting outer pipe 1. The space between the inner and outer pipes 1, 9 is filled with a filler 14 causing a bend thereof due to distortion in the ground 2. Inside the distortion- detecting inner pipe 9, there is disposed a distortion-detecting rope-shaped body 14 having a lower end fixed to a lower end of the distortion-detecting outer pipe 1 and an upper end capable of being displaced downward by a bend of the rope-shaped body 13 due to the bend of the distortion-detecting inner pipe 9. A detection means 15 is linked to an upper end of the distortion-detecting rope-shaped body 13 so that the downward displacement thereof can be detected by it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting ground distortion such as landslides caused by torrential rainfall and crustal deformation due to volcanic activity, and for predicting and preventing disasters.

[0002]

2. Description of the Related Art Conventionally, a description will be given of an example of this type of a ground strain detecting device. A pillar is erected at two places separated in a direction in which a strain is expected to occur in the ground. One of the supports is erected so that the lower end thereof reaches an immovable land (immovable part) and is fixed, and the other support is erected so that the lower end thereof is in a movable state where it does not reach the immovable ground. You. A strain detection line made of Invar is stretched between the protrusions on the ground surface of both columns. This strain detecting line is covered by a protective pipe so as to be inserted into the center thereof. A recording pen is attached at a position closer to one of the columns in the strain detection line, and a roll-shaped recording paper is arranged corresponding to the recording pen,
The recording paper is rotated at a gentle rotation speed by the driving means, and the state of the ground is sequentially recorded on the recording paper rotated by the recording pen.

[0003] When distortion occurs in the ground and the position of the movable support with respect to the fixed support fluctuates, the recording state of the recording pen on the recording paper changes due to bending of the strain detection line. Therefore, it is possible to determine the presence or absence of the ground distortion and the magnitude of the distortion, that is, early determination of the landslide or the like and grasp of the behavior of the landslide or the like by this change.

[0004] Another example of the conventional ground strain detecting device will be described. A pillar is erected at two places separated in a direction in which strain is expected to occur in the ground. One of the columns is erected so that the lower end thereof reaches a fixed ground and is fixed, and the other column is erected such that the lower end thereof is in a movable state where it does not reach the fixed ground. The rotating body for distortion detection is supported on the protruding surface of the movable support so as to be rotatable about a horizontal axis. One end of an invar-made strain detecting wire is connected to the surface protruding portion of the fixed support, and the other side of the strain-detecting wire is hung on the strain detecting rotating body and is hung down.
A weight is attached to the lower end. The strain detecting wire is covered by a protective pipe so as to be inserted into the center thereof.

[0005] When distortion occurs in the ground and the position of the movable support with respect to the fixed support fluctuates, the strain detecting rotator is rotated by the strain detecting wire. Therefore, by measuring the rotation angle of the distortion detecting rotator, it is possible to determine whether or not the ground is generated and to determine the magnitude of the distortion, that is, early determination of a landslide or the like, and grasp of a behavior of the landslide or the like.

Another example of a conventional ground strain detecting device will be described. Strain gauges are attached to the surface of a flexible pipe at desired intervals along the axial direction. The pipe is buried in the ground in the depth direction, and the lower end of the pipe reaches a fixed ground and is held in a fixed state. At this time, the strain gauge is arranged so as to face the direction in which the occurrence of strain is expected.

[0007] When distortion occurs in the ground and the pipe is bent, the electric resistance of the strain gauge at that portion changes. Therefore, it is possible to determine whether or not the ground is strained due to the change in the electric resistance and to determine the magnitude of the strain, that is, early determination of a landslide or the like and grasp of a behavior of the landslide or the like.

[0008]

However, among the above-mentioned conventional examples, in the first conventional example and the second conventional example, the generation of the distortion in the direction of the distortion detecting filament is expected. In the third conventional configuration, the strain gauges must be arranged in a direction in which the occurrence of strain is expected. For this reason, it is necessary to investigate in advance the direction of occurrence of distortion on the ground at the installation site. As a result, not only is the construction cost increased, but also the construction requires attention and is troublesome. Further, as described above, in any of the conventional examples, since the installation direction is determined by the direction in which the strain is generated, it cannot be used on the ground where the direction in which the strain is generated cannot be predicted.

In the first and second conventional examples, the measuring person goes to the installation site almost every day to record on the recording paper by the recording pen or to rotate the rotating body for detecting distortion. Since it is necessary to check the angle, the management cost is high. Further, the occurrence of distortion in the surface portion of the ground can be detected, but the occurrence of distortion in a deep portion cannot be detected. On the other hand, in the third conventional example, since the output of the strain gauge can be transmitted to a management center or the like by radio or the like, the management cost is low, but a large number of strain gauges are required. ,
It will be expensive.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and it is possible to detect ground distortion in an arbitrary direction. It is possible to detect ground distortion by performing construction without prior investigation, and to detect ground distortion by performing construction even on ground where the direction of occurrence of distortion cannot be predicted. Ground strain of each layer in the vertical direction can be detected, therefore, the construction can be simplified, the cost can be reduced, and the detection capability can be improved. To provide.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problem, a ground strain detecting apparatus according to the present invention is embedded in a ground in a depth direction, and is capable of detecting a strain which can be refracted in an arbitrary direction due to ground strain. An outer tube for use, and an inner tube for strain detection that is arranged along the axial direction inside the outer tube for strain detection and can be refracted in any direction,
Filled between the inner periphery of the outer tube for distortion detection and the outer periphery of the inner tube for distortion detection, and refracts the outer tube for distortion detection due to ground distortion, and refracts the inner tube for distortion detection. Material, the lower end is disposed inside the inner tube for strain detection, the lower end is held in a fixed state at the lower end of the outer tube for strain detection, and the upper end is bent by the refraction of the inner tube for strain detection. A strain detecting rope that can be displaced downward is linked to an upper end of the strain detecting rope, and the upper end of the strain detecting rope is displaced downward to detect this displacement. And detection means.

[0012] In the above structure, the strain detecting outer pipe is divided and connected at desired intervals in the depth direction of the ground, and the strain detecting inner pipe is continuously connected to be a refractible synthetic resin. It is preferable to use a wire or a wire rope as the wire for strain detection.

[0013] Further, as detecting means, a supporting member attached to the ground, an operating member rotatably connected to the supporting member and connected to an upper end portion of the strain detecting cable, and a mounting member attached to the supporting member. The main body of the detector has an operating member linked to the operating member, and the upper end side of the strain detecting cord is displaced downward due to ground strain, and the operating member rotates to operate the operating member. Thereby, the detector for detecting the displacement and the operating member are held in the strain detection cable-like body so that the detector is not detected in a state where the displacement due to the distortion of the ground is not generated. And a spring.

Further, as a detecting means, a box body which is attached to the upper end of the outer tube for strain detection in a communicating state, is rotatably connected to the inside of the box, and is connected to the upper end of the rope for strain detection. An actuating member, a detector main body mounted in the box body, and an operating member linked to the actuating member, wherein an upper end side of the strain detecting cable is displaced downward due to ground strain, and the actuating member When the operation member is rotated and the operation member is operated, the detector for detecting the displacement, and the detector for detecting the displacement of the actuating member in the rope for distortion detection without causing the displacement due to the distortion of the ground. And a spring for holding it in a non-detection state. In this case, it is preferable that the box is buried in the ground.

According to the present invention configured as described above,
When distortion occurs in the ground, the outer tube for distortion detection is refracted, and accordingly, the inner tube for distortion detection and the cord for distortion detection inside the inner tube for distortion detection are refracted via the filler. Since the lower end portion of the strain detecting cable is held in the positioning state, the upper end side is displaced downward by refraction, and this displacement can be detected by the detecting means. In this way, ground distortion in an arbitrary direction can be detected, and therefore, it is possible to detect ground distortion by constructing the ground at the installation site without prior investigation of the direction in which the distortion is generated. Construction can be performed even on the ground where the direction of occurrence of the ground cannot be predicted, and the distortion of the ground can be detected.
Further, the ground strain of each layer in the depth direction of the ground can be detected.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described. FIGS. 1 to 4 show a ground distortion detecting apparatus according to a first embodiment of the present invention, FIG. 1 is an overall configuration diagram of an installed state, and FIG. 2 is an overall configuration diagram of a distortion detection state when distortion occurs. 3 and 4 are outer tubes for strain detection,
FIG. 3 is an enlarged view of an upper end portion and an enlarged cross-sectional view of a lower end portion of the strain detection inner tube and the strain detection cord.

As shown in FIGS. 1 to 3, the outer tube 1 for detecting strain is made of vinyl chloride or a metal having corrosion resistance. The outer tube 1 for strain detection is buried in the ground 2 in the depth direction, but is divided at desired intervals in the axial direction (the depth direction of the ground) so as to be easily refracted in an arbitrary direction due to the strain of the ground 2. The divided short tubes 3 are sequentially connected to one another by fitting the fitting projection 4 and the fitting recess 5. Holes 6 are formed at a plurality of locations around the lower end of the outer tube 1 for strain detection, and screw holes 7
And a hole 8 are formed.

The strain detecting inner tube 9 is formed of a flexible vinyl or the like so as to be refracted in an arbitrary direction, and is arranged inside the strain detecting outer tube 1 along the axial direction. It is formed to have a small diameter so that a relatively large space is formed with the inner peripheral surface of the outer tube 1. A hole 10 is formed at the lower edge of the inner tube 9 for strain detection so as to face the same. The fixing member 11 is formed of a hard synthetic resin, metal, or the like into a rod shape, and has a screw portion 12 at an end. The fixing member 11 is inserted into the hole 8 of the outer tube 1 for strain detection and the hole 10 of the inner tube 9 for strain detection from the screw portion 12 side, and the screw portion 12 is screwed into the screw hole 7 of the outer tube 1 for strain detection. It is worn and fixed. The position of the upper end of the inner tube 9 for strain detection is set to substantially match the position of the upper end of the outer tube 1 for strain detection.

The strain detecting cable 13 is preferably made of a low expansion material such as invar, and various structures such as a wire, a wire rope, and a chain can be used.
In the present embodiment, a wire is used. Wire 1
Reference numeral 3 denotes a lower end fixed to the center of the fixing member 11, disposed inside the strain detecting inner tube 9, and an upper end of the wire 13 set to protrude above the strain detecting inner tube 9. I have. In this manner, the lower end of the wire 13 is fixed to the lower end of the outer tube 1 for strain detection, and the outer peripheral surface and the inner peripheral surface of the inner tube 9 for distortion detection are connected to the outer peripheral surface of the outer tube 1 for distortion detection and the wire 13. A substantially uniform interval can be maintained on the circumference.

A filler 14 is filled between the inner periphery of the outer tube 1 for strain detection and the outer periphery of the inner tube 9 for strain detection during construction. The filler 14 is made of a material capable of refracting the inner tube 9 for strain detection with the refraction of the outer tube 1 for strain detection, for example, foamed cement, earth and sand on site, and the like.

The detecting means 15 in this embodiment is provided on the surface of the earth. More specifically, a support arm 16b protrudes in a horizontal direction above a support 16a standing on the ground 2, and an elbow of a bell crank 17 serving as an operating member is provided at a tip of the support arm 16b in a horizontal axis. Are connected rotatably. The support arm 16 has a support arm 16a.
Variable resistor 1 used as a detector above b
The base of the main body 19 is mounted, and the distal end of the operating member 20 of the variable resistor 18 is rotatably connected to one side of the bell crank 17 by a horizontal shaft. The upper end of the wire 13 is connected to the tip of the other side of the bell crank 17 so as to allow the bell crank 17 to rotate. Operating member 2 of upper end of support 16a and bell crank 17
A tension spring 21 is stretched at the leading end on the connection side of No. 0 to prevent the bell crank 17 from rotating due to the load of the wire 13 due to the elasticity of the tension spring 21, that is, the operation member 20 of the variable resistor 18. Is kept from operating.

In order to use the above-described ground strain detector,
In a place where a disaster may occur due to distortion of the ground 2 such as landslide or crustal deformation, a hole 22 is firstly excavated in the ground 2 by an auger (not shown) in a desired arrangement. Next, a fixing member 11 is attached to the lower end of the outer tube 1 for strain detection.
With the lower end portions of the strain detecting inner tube 9 and the wire 13 fixed, the strain detecting outer tube 1, the strain detecting inner tube 9 and the wire 13 are integrally inserted into the auger hole 22.
Next, cement milk 23 is poured from the ground into the inner lower end of the outer tube 1 for strain detection, and a part of the cement milk 23 is exuded into the ground 2 through the hole 6 at the lower end of the outer tube 1 for strain detection. And solidify. Thus, the lower end portions of the outer tube 1 for strain detection, the inner tube 9 for strain detection, and the wire 13 can be held in the ground 2 in a fixed state.

Next, a filling material 14 is filled in the inner circumference of the outer tube 1 for strain detection and the outer circumference of the inner pipe 9 for strain detection. The filler 14 prevents the inner tube 9 for strain detection from being crushed at the time of filling, and allows the wire 13 to slide with respect to the inner tube 9 for strain detection. The filler 14 is made of a material such as earth and sand excavated by an auger, foam cement, or the like that can refract the outer tube 1 for strain detection and the inner tube 9 for strain detection due to the distortion of the ground 2. Is used. On the other hand, the support 16a of the detection means 15 is erected on the ground 2. Next, the upper end of the wire 13 is connected to the bell crank 17 of the detecting means 15. Then, for example, the output section of the variable resistor main body 19 is connected to a wireless transmission means or the like by a conducting wire (not shown), and the input section of the variable resistor main body 19 is connected to a power supply (not shown) such as a solar cell or a storage battery. To complete the construction.

In the state shown in FIG. 1 in which no distortion occurs in the ground 2, the variable resistor 18 in which the bell crank 17 does not operate due to the tension of the tension spring 21 is kept in a non-detection state. Now, it is assumed that distortion occurs in the ground 2 due to crustal deformation or the like, and as shown in FIG. 2, an earth pressure X is applied to the distortion detection outer pipe 1. At this time, as described above, the outer tube 1 for strain detection is divided and connected at desired intervals, for example, at intervals of 500 mm, and the filler 14 is bent by the outer tube 1 for distortion detection and the inner tube 9 for distortion detection. The outer tube 1 for strain detection is refracted by the earth pressure X, and the inner tube 9 for strain detection is
Is refracted. Accordingly, the wire 13 is bent. At this time, since the lower end of the wire 13 is held in the ground 2 by the strain detecting outer tube 1 as described above, the upper end is displaced downward by refraction. Along with this, the bell crank 17 is rotated against the tensile force of the tension spring 21, and the operation member 20 of the variable resistor 18 is pulled,
The resistance value or voltage output from the variable resistor 18 changes. The changed output is received by the wireless receiving means or the like of the management center via the wireless transmitting means or the like, and can be analyzed by the management center.

As a result of the analysis, when it is determined that there is a possibility of crustal deformation, a disaster or the like can be prevented beforehand by notifying the residents in the vicinity. If the detection information from the detection means 15 is transmitted to the management center in this way, it is not necessary for the measurement staff or the like to go to the site as in the related art, and therefore, it is possible to significantly reduce the management costs and the like. .

Next, a second embodiment of the present invention will be described. FIG. 5 is an overall configuration diagram of an installed state showing a ground strain detection device according to a second embodiment of the present invention.

In the first embodiment, the detecting means 15 is exposed above the ground, whereas in the present embodiment, the structure is different in that the detecting means 15 is buried underground. Therefore, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and different configurations will be mainly described.

As shown in FIG. 5, a box 24 is attached to the upper end of the outer tube 1 for strain detection. The box 24 includes a main body 25, an inner lid 6, and an outer lid 27, and is formed of vinyl chloride or the like. The lower end of the main body 25 is attached to the upper end of the distortion detecting outer tube 1 in a communicating state, the inner lid 26 is attached to the upper end of the main body 25, and the main body 25 and the inner lid 26 are covered with the outer lid 27, and the inside is waterproof. Have been. In the main body 25, a base portion of an arm 28, which is an operation member, is rotatably mounted on a horizontal axis. The base of the main body 19 of the variable resistor 18 used as a detector is attached to the inner side of the inner lid 26, and the tip of the operating member 20 of the variable resistor 18 is attached to the tip of the arm 28 by a horizontal shaft. Are connected rotatably.

An upper end of the wire 13 is connected to an intermediate portion of the arm 28 so as to allow the arm 28 to rotate. A tension spring 21 is stretched between the arm 28 and the inner lid 26 at a position opposite to the connection position of the operation member 20 with respect to the connection position of the wire 13 on the arm 28.
Is held so that the arm 28 does not rotate due to the load of the wire 13, that is, the operation member 20 of the variable resistor 18 does not operate.

In order to use the ground strain detecting device in this embodiment, a hole 22 is excavated in the ground 2 in the depth direction by an auger as in the above embodiment, and an upper portion of the hole 22 on the surface side of the ground is a large-diameter hole. 29. Next, similarly to the first embodiment, the outer tube 1 for strain detection, the inner tube 9 for strain detection, and the wire 13 are integrally inserted into the auger hole 22, and the outer tube 1 for strain detection is Thus, the wire 13 is fixed in the ground 2 and the lower end of the wire 13 is held in the positioned state. After filling the filler 14 around the outer tube 1 for strain detection and the inner tube 9 for strain detection, the upper end of the wire 13 is connected to the arm 28 and the main body 25 of the box 24 is distorted in the hole 29. Outer tube for detection 1
And the box 24 is buried with earth and sand at the site.

In the state shown by the solid line in FIG. 5 where no distortion occurs in the ground 2, the variable resistor 18 in which the arm 28 does not operate due to the tensile force of the tension spring 21 is held in the non-detection state. Now, it is assumed that strain is generated in the ground 2 which is inclined due to concentrated torrential rain and the like, a slip surface Y is generated in the ground 2 as shown by a dotted line in FIG. 5, and earth pressure is applied to the outer tube 1 for strain detection. At this time, as described above, the outer tube 1 for strain detection is divided and connected at desired intervals, for example, at intervals of 500 mm.
Since the filler 14 does not hinder the refraction of the outer tube 1 for strain detection and the inner tube 9 for strain detection, the outer tube 1 for strain detection is refracted by the earth pressure due to the slip surface Y as shown by a chain line in FIG. The inner tube 9 for strain detection is refracted via the filler 14. Along with this,
The wire 13 is bent. At this time, since the lower end of the wire 13 is held in the ground 2 by the strain detecting outer tube 1 as described above, the upper end is displaced downward by refraction. Accordingly, the arm 28 is connected to the tension spring 2
The rotating member is rotated against the pulling force of 1, and the operating member 20 of the variable resistor 18 is pulled, so that the resistance value or the voltage output from the variable resistor 18 changes. The changed output is received by the wireless receiving means or the like of the management center via the wireless transmitting means or the like, and can be analyzed by the management center.

As a result of the analysis, if it is determined that there is a risk of a landslide or the like, a disaster or the like can be prevented beforehand by notifying the residents or the like in the vicinity. If the detection information from the detection means 15 is transmitted to the management center in this way, it is not necessary for the measurement staff or the like to go to the site as in the related art, and therefore, it is possible to significantly reduce the management costs and the like. .

According to the present embodiment, since the detection means 15 is buried in the ground, it is possible to prevent malfunction due to collision of animals.

In the first embodiment, the detecting means 15 can be covered with a box to prevent malfunction. Further, the outer tube for strain detection 1 is divided and connected, but may be connected to one another if it is formed of a refractible material. The lower end of the outer tube 1 for strain detection is ground 2
The blade member may be buried in an immovable ground (immovable part) inside, or a blade member may be attached to the lower end portion, and after inserting into the ground 2, the blade member may be expanded and stopped.
The inner tube 9 for strain detection is composed of the outer tube 1 for strain detection and the wire 1.
In order to make it easy to create an almost uniform space on the circumference between
Although the lower end is fixedly attached to the fixing member 11, it is not always necessary to fix the lower end.
After inserting 3 into the hole 22 of the ground 2, it can also be inserted. Further, a variable resistor 18 is used as a detector of the detecting means 14.
A switch for ON and OFF can be used in place of the above. Further, various detecting means such as a recording means using a recording paper and a recording pen as in the conventional example, a rotation angle detecting means by rotating a rotator for distortion detection, and the like. Means can be employed. In addition, the present invention can be variously changed in design without changing the basic technical idea.

[0035]

As described above, according to the present invention, when distortion occurs in the ground, the outer tube for strain detection bends, and accordingly, the inner tube for strain detection and the inside of the tube for strain detection are interposed via the filler. The strain detecting cord is bent. Since the lower end portion of the strain detecting cable is held in the positioning state, the upper end side is displaced downward by refraction, and this displacement can be detected by the detecting means. In this way, ground distortion in an arbitrary direction can be detected, and therefore, it is possible to detect ground distortion by constructing the ground at the installation site without prior investigation of the direction in which the distortion is generated. Construction can be performed even on the ground where the direction of occurrence of the ground cannot be predicted, and the distortion of the ground can be detected.
Further, the ground strain of each layer in the depth direction of the ground can be detected. Therefore, construction is easy, and
The cost can be reduced, and the detection capability can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an installed state of a ground strain detection device according to a first embodiment of the present invention.

FIG. 2 shows the distortion detection device, and is an overall view of a distortion detection state.

FIG. 3 is an enlarged view showing upper end portions of an outer tube for distortion detection, an inner tube for distortion detection, and a cord for distortion detection in the distortion detection device.

FIG. 4 is an enlarged sectional view showing a lower end portion of an outer tube for distortion detection, an inner tube for distortion detection, and a cord for distortion detection in the distortion detection device.

FIG. 5 is an overall configuration diagram illustrating an installed state of a ground strain detection device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer pipe for strain detection 2 Ground 9 Inner pipe for strain detection 13 Wire (cord for strain detection) 14 Filler 15 Detecting means 17 Bell crank (operating member) 18 Variable resistor (detector) 19 Main body 20 Operating member 21 Tension spring 23 Cement milk

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D044 EA07 2F063 AA25 BA16 CA01 CA13 DA02 DA08 EA02 FA01 KA01 KA03 NA01 ZA01 2F073 AA01 BC02 CC02 2F076 BA11 BB09 BD02 BD17 BE18

Claims (7)

[Claims] 1. A strain detecting outer tube buried in the ground in a depth direction and capable of being bent in an arbitrary direction due to ground strain, and disposed inside the strain detecting outer tube along an axial direction. The inner tube for strain detection, which can be bent in any direction, is filled between the inner periphery of the outer tube for strain detection and the outer periphery of the inner tube for strain detection, and the outer tube for strain detection due to ground distortion. Along with refracting the filler for refracting the inner tube for strain detection, the lower end is disposed inside the inner tube for strain detection and the lower end is held in a fixed state at the lower end of the outer tube for strain detection, A strain detecting rope that can be displaced downward at the upper end by being refracted by the refraction of the distortion detecting inner tube, and a strain detecting rope that is linked to the upper end of the strain detecting rope. And a detecting means for detecting the displacement by displacing the upper end of the ground downward. 2. The ground strain detecting device according to claim 1, wherein the strain detecting outer pipe is divided and connected at desired intervals in a depth direction of the ground. 3. The ground strain detecting device according to claim 1, wherein the strain detecting inner pipe is formed of a synthetic resin that is continuous and refractible. 4. The ground strain detecting apparatus according to claim 1, wherein the strain detecting cord-like body is made of a wire or a wire rope. 5. A detecting means, comprising: a supporting member mounted on the ground; an operating member rotatably connected to the supporting member; and an operating member connected to an upper end portion of the strain detecting cable, and a detecting means mounted on the supporting member. The main body of the detector has an operating member linked to the operating member, and the upper end side of the strain detecting cord is displaced downward due to ground strain, and the operating member rotates to operate the operating member. Thereby, the detector for detecting the displacement and the operating member are held in the strain detection cable-like body so that the detector is not detected in a state where the displacement due to the distortion of the ground is not generated. 5. The method according to claim 1, further comprising a spring.
The ground strain detecting device according to any one of the above. 6. A box attached to an upper end of the outer tube for strain detection in a communicating state with the detecting means, rotatably connected to the box, and connected to an upper end of the rope for strain detection. An actuating member, a detector main body mounted in the box body, and an operating member linked to the actuating member, wherein an upper end side of the strain detecting cable is displaced downward due to ground strain, and the actuating member When the operation member is rotated and the operation member is operated, the detector for detecting the displacement, and the detector for detecting the displacement of the actuating member in the rope for distortion detection without causing the displacement due to the distortion of the ground. The ground strain detecting device according to any one of claims 1 to 4, further comprising a spring for holding the ground so as to be in the non-detecting state. 7. The ground strain detecting device according to claim 6, wherein the box is buried in the ground.