CN108871222B - Wide-range fiber grating aperture deformer and checking method thereof - Google Patents
Wide-range fiber grating aperture deformer and checking method thereof Download PDFInfo
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- CN108871222B CN108871222B CN201810884334.8A CN201810884334A CN108871222B CN 108871222 B CN108871222 B CN 108871222B CN 201810884334 A CN201810884334 A CN 201810884334A CN 108871222 B CN108871222 B CN 108871222B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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Abstract
The application discloses a wide-range fiber bragg grating aperture deformer and a checking method thereof, wherein the deformer comprises the following components: a housing; the fixed base material is arranged in the shell and comprises a pair of cantilever beams which are axially arranged and symmetrically arranged relative to the axle center of the deformation meter, and a rigid connecting piece which is used for connecting the two cantilever beams and can only rigidly move along the radial direction; the rigid force transmission piece is arranged on the cantilever beam and provided with a protruding part which faces to the outer side and protrudes out of the shell body to be in contact with the side wall of the drilling hole, and when the side wall of the drilling hole is deformed, the protruding part drives the cantilever beam to generate corresponding deflection deformation; and the grating wavelength of the measuring fiber grating arranged on the cantilever beam changes along with the deflection change of the cantilever beam.
Description
Technical Field
The present disclosure relates generally to the field of underground engineering surrounding rock stress testing, and in particular to a wide-range fiber bragg grating aperture deformer for measuring surrounding rock stress for a long time and a checking method thereof.
Background
With the increase of coal exploitation depth, geological conditions are more and more complex, surrounding rock stress is continuously increased, rock burst disasters are continuously increased, and the safety of underground personnel and equipment is seriously threatened. The stress field of surrounding rock directly affects the stress, deformation and damage of the rock coal body, and is basic data for predicting rock burst disasters; therefore, the long-term accurate monitoring of the stress of the surrounding rock has a higher guiding effect on predicting rock burst disasters.
The pore diameter deformation method is a surrounding rock stress testing method with the longest development time and mature technology. Has wide applicability and higher reliability. The conventional aperture deformation method calculates the stress state in a plane perpendicular to the axis of a borehole by measuring the deformation of the borehole diameter, and determines the three-dimensional stress state of a point by measuring three mutually unequal boreholes. Because the aperture deformation method does not need to adhere the sensor and the rock wall together through glue, the method has the advantages of simple installation process, less influencing factors and high measurement accuracy. But the currently adopted aperture deformation meter calculates the aperture deformation and the corresponding surrounding rock stress through the strain gauge. Because of the poor corrosion resistance and electromagnetic interference resistance of the resistive strain gage, the resistive strain gage is difficult to be applied to the condition of complex electromagnetic fields under the well. Meanwhile, the resistance strain gauge is easy to drift and fast in output signal attenuation when the temperature changes, so that the resistance strain gauge cannot adapt to conditions of obvious temperature change, long-distance acquisition, transmission and the like. Thus, currently employed aperture deformers are only used in short-term measurements of the surrounding rock raw rock stress and cannot be used for long-term monitoring of the surrounding rock stress.
The optical fiber grating sensing is one new type of sensing technology, and has optical fiber grating adhered to the base material, and when the base material is deformed by external force, the wavelength of the grating will change and the deformation and stress of the base material are calculated via the change in the wavelength of the grating. Publication [ publication No.: CN107328370A, CN206818160U fixes the fiber grating on the steel ring based on the fiber grating sensing principle, which solves the technical problem of monitoring the stress of surrounding rock for a long time; however, due to the limitation of the structural form, the maximum range is not more than 1.0 mm. When the situation that the surrounding rock is relatively softer and the stress change is larger is met, the borehole diameter is larger in deformation, the disclosed sensor fiber bragg grating can generate a chirp phenomenon, and the stress change of the surrounding rock cannot be accurately monitored. Therefore, development of a wide-range fiber bragg grating aperture deformer capable of monitoring the stress of surrounding rocks for a long time is urgently needed to solve the technical problem of long-term stress monitoring in different surrounding rock types.
Disclosure of Invention
In view of the foregoing drawbacks or shortcomings of the prior art, it is desirable to provide a wide-range fiber bragg grating aperture deformer for long-term measurement of surrounding rock stress and a method of calibrating the same.
In a first aspect, an embodiment of the present application provides a wide-range fiber bragg grating aperture deformer for long-term measurement of surrounding rock stress, including:
a housing;
The fixed base material is arranged in the shell and comprises at least one pair of cantilever beams which are axially arranged and symmetrically arranged relative to the axle center of the deformation meter, and a rigid connecting piece which is used for connecting the two cantilever beams and can only rigidly move along the radial direction;
The rigid force transmission piece is arranged on the cantilever beam and provided with a protruding part which faces to the outer side and protrudes out of the shell body to be in contact with the side wall of the drilling hole, and when the side wall of the drilling hole is deformed, the protruding part drives the cantilever beam to generate corresponding deflection deformation;
And the grating wavelength of the measuring fiber grating arranged on the cantilever beam changes along with the deflection change of the cantilever beam.
The aim and the technical problems of the invention can be further realized by adopting the following technical measures.
The cantilever beam comprises an equal-strength beam area, the fiber gratings are arranged at the equal-strength beam area, and even if the two measuring fiber gratings are different along the installation position of the cantilever beam, the wavelength change measured by the two fiber gratings corresponding to each pair of the cantilever beams can be ensured to be equal, namelyThe accuracy and stability of the monitored values are ensured.
The measuring fiber gratings are at least provided with four pairs, and the four pairs of measuring fiber gratings are uniformly distributed in the circular projection of the shell along the cross section. The four pairs of measuring fiber gratings are uniformly arranged in the projection of the vertical axis plane, and the four pairs of measuring fiber gratings respectively correspond to 0 degrees, 45 degrees, 90 degrees and 135 degrees under a local coordinate system.
According to the theory of elastic mechanics, the wavelength variation of each measuring fiber grating has the following relation. In the actual monitoring process, the above relation can be used for checking and checking the results, and unreasonable results can be removed in time, so that the monitoring precision is greatly improved.
The cantilever beam is made of spring steel.
The deformation meter further comprises a fixed support for setting the fixed base material.
The fixed support comprises a support connecting part fixedly connected with the shell and a substrate fixing part used for setting the fixed substrate.
The substrate fixing part is of a cylindrical structure, a through hole for the rigid connecting piece to pass through is formed in the substrate fixing part, the size of the through hole is matched with the cross section size of the rigid connecting piece, and rotation of the rigid connecting piece is limited, so that the rigid connecting piece can only rigidly move along the radial direction.
The fixed support comprises a first fixed support part and a second fixed support used for fixing the same rigid connecting piece, the first fixed support and the second fixed support are fixedly arranged in the shell, a first through hole is formed in the first fixed support, a second through hole is formed in the second fixed support, and the first through hole and the second through hole are used for penetrating the rigid connecting piece and only allowing the rigid connecting piece to rigidly move along the radial direction.
The deformation meter further comprises a temperature compensation fiber grating which is arranged at the rear end of the shell and is in a free deformation state.
In a second aspect, the embodiment of the application also provides a checking method of a wide-range fiber bragg grating aperture deformer for measuring surrounding rock stress for a long time, which comprises the following steps:
The deformation meter is arranged in a center penetrating round hole of the organic glass block, and the organic glass block is uniform in material quality and isotropy;
applying pressure to the organic glass block, wherein the direction of the pressure is perpendicular to a plane parallel to the axis direction of the round hole, checking whether the wavelength change and the pressure change of the measured fiber bragg grating in different directions are in good linear relation, and if not, checking disqualification by a deformation meter;
Checking whether the wavelength changes of the two corresponding fiber bragg gratings on each pair of cantilever beams are equal, if not, checking disqualification by the deformer;
And checking whether the sum of the wavelength variation values of the two staggered queues of fiber gratings is equal to the sum of the wavelength variation values of the other two queues of fiber gratings, and if not, checking disqualification by the deformer.
The fiber grating aperture deformer provided by the embodiment of the application is based on the fiber grating sensing principle, the fiber gratings are welded on the cantilever beams made of spring steel, and the paired cantilever beams can rigidly move along the radial direction, so that the measurement accuracy can be ensured. The structure ensures that the deformation meter has the characteristics of electromagnetic interference resistance, corrosion resistance, high precision, good long-term stability and the like. Meanwhile, the cantilever beam is adopted as the fiber grating substrate, the measuring range of the deformation meter can be adjusted by adjusting the length of the beam, the deformation meter can be suitable for long-term monitoring of surrounding rock stress under the conditions of different lithology and different stress levels, the application range of the deformation meter is improved, and the problem of long-term monitoring of surrounding rock three-dimensional stress in a complex environment is solved.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:
FIG. 1 shows a schematic diagram of a deformation gauge in an embodiment of the application;
FIG. 2 shows a schematic view of a structure of a fixing support in an embodiment of the application;
FIG. 3 illustrates a cantilever beam profile in an embodiment of the present application;
FIG. 4 illustrates a front view of a cantilever beam in an embodiment of the present application;
FIG. 5 illustrates a top view of a cantilever beam in an embodiment of the present application;
FIG. 6 illustrates a left side view of a cantilever beam in an embodiment of the present application;
FIG. 7 shows a graph of the deformation of the hole wall and the wavelength change of the measured fiber grating in an embodiment of the application;
FIG. 8 shows a graph of the relationship between the applied pressure and the wavelength variation of each fiber grating in the precision calibration test in the embodiment of the present application;
FIG. 9 shows wavelength variation curves of two fiber gratings on each pair of cantilevers in an accuracy calibration test in an embodiment of the present application;
FIG. 10 shows the variation curves of fiber gratings in different orientations in a precision calibration test in an embodiment of the present application;
FIG. 11 shows a graph of the wavelength variation of a measured fiber grating under different deformation conditions in an embodiment of the present application;
FIG. 12 shows the results of stress calculation errors for an cantilever beam aperture strain gauge in an embodiment of the application;
Fig. 13 shows a front view of a mounting bracket structure in another embodiment of the application.
The device comprises a 1-stainless steel shell, a 2-fixed support, a 3-cantilever beam, a 4-measuring fiber grating, a 5-force transmission cap, a 6-temperature compensation fiber grating, a 7-armored optical cable, an 8-rigid connecting piece, a 9-support connecting part, a 10-substrate fixing part, a 11-first fixed support and a 12-second fixed support.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. For convenience of description, only parts related to the invention are shown in the drawings.
It should be noted that the components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations without conflict. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "axial", "lateral", "vertical", "horizontal", "inner", "outer", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood as appropriate by those of ordinary skill in the art.
Referring to fig. 1, an optical fiber grating aperture deformation sensor for measuring surrounding rock stress for a long time is shown, and mainly comprises a stainless steel shell 1, a fixed support 2, a cantilever beam 3, a measuring optical fiber grating 4, a force transmission cap 5, a temperature compensating optical fiber grating 6 and an armored optical cable 7.
The stainless steel shell 1 is made of stainless steel, is divided into three sections along the axis, the front section is hemispherical, and plays a role in guiding when entering a borehole, and the radius of the sphere is 3 cm; the middle part and the rear end are provided with cylindrical cavities, the middle part is mainly used for arranging measurement, and is cylindrical, the length is 12 cm, the outer diameter is 34 mm, and the thickness is 4 mm; the rear end is a conical section for clamping the rock wall fixed sensor, and the wall thickness is 4mm and the length is 10 cm.
The fixed support is fixed in the cavity of the stainless steel shell through bolts, is made of stainless steel and is composed of three parts, wherein the front end is a disc used as a support connecting part 9 and is fixed with the stainless steel shell, the middle part is a cylinder used as a base material fixing part 10 and is used for fixing a cantilever, and the rear end is a disc with a threading hole and is used as a passage of an optical fiber. The front end and the rear end of the fixed support 2 are both discs with the outer diameter of 28mm and the height of 5mm; the middle part is a cylinder with the outer diameter of 20 mm and the height is 8cm. The cantilevers Liang Chengdui are arranged with each pair of cantilevers connected by a rigid connection 8 as shown in fig. 4. The cylinder is provided with a through hole which is arranged along the diameter direction and used for the rigid connecting piece to pass through, and the cross section size of the through hole is approximately the same as that of the rigid connecting piece, so that the rigid connecting piece passes through the axle center, can freely move along the radial direction, and can restrict the rotation of the rigid connecting piece and the movement along other directions. The displacement of the fixed end of the cantilever beam connected with the rigid connecting piece is limited by the fixed support, so that the cantilever beam can only move radially but cannot rotate or displace annularly.
The cantilever beam is an equal-strength beam made of spring steel, namely the strain of any position on the surface of the beam is the same when the cantilever beam is deformed; the spring is made of 60Si2MnA spring steel, and has the length of 35 mm, the thickness of 1 mm and the width of 3-6 mm (linear change).
In this embodiment, four pairs of cantilever beams are provided. It should be noted that even if fewer than four pairs, or even a pair of cantilever beams, are provided, it is within the scope of the present application to measure the deformation of one or more of the radial directions.
In the embodiment of the application, four pairs of cantilever beams are arranged at equal intervals along the axial direction of the deformation meter (adjacent intervals are 7 mm), and are uniformly arranged in a vertical axial plane (as shown in fig. 3, the four pairs of cantilever beams respectively correspond to 0 degree, 45 degree, 90 degree and 135 degree under a local coordinate system). The measuring fiber grating 4 is welded in the equal-strength area inside the cantilever beam 3, and as shown in fig. 4, the fiber grating measures the bending direction strain of the cantilever beam.
It will be appreciated that the above-described fixed support may take other specific forms to achieve the corresponding function. For example, the substrate fixing portion 10 for fixing a rigid connection member may be two parts symmetrically disposed along the axial direction, and each part may be a unitary structure or a detachable structure. It is within the scope of the present application that the mounting bracket includes a bracket attachment portion for fixedly attaching to the housing and a through hole for the rigid connector to pass through, the through hole allowing only radial rigid movement of the rigid connector. Fig. 13 illustrates a specific embodiment, where only a pair of substrate holders and a pair of cantilevers are shown: the substrate fixing part 10 comprises a first fixing support 11 and a second fixing support 12 for fixing the same rigid connecting piece, wherein the first fixing support and the second fixing support are fixedly arranged in the shell, a first through hole is formed in the first fixing support, a second through hole is formed in the second fixing support, and the first through hole and the second through hole are used for penetrating the rigid connecting piece 8 and only allowing the rigid connecting piece to rigidly move along the radial direction. In such an embodiment, the same rigid connector is secured to two oppositely disposed fasteners having vias, and if four pairs of cantilevered beams are required, four corresponding pairs of securing mounts are required.
The force transmission cap 5 as a rigid force transmission piece is made of stainless steel, and the front end of the force transmission cap is contacted with the hole wall and is hemispherical with the diameter of 5 mm; the rear end is cylindrical and is in contact with the cantilever beam, and the diameter of the rear end is 5 mm.
It is understood that the rigid force transmission member is not limited to the above specific structural form, and it is within the scope of the present application as long as the "protrusion portion disposed on the cantilever beam and protruding outside the housing to contact with the sidewall of the borehole" is satisfied, and when the sidewall of the borehole is deformed, the protrusion portion drives the cantilever beam to deform in a corresponding deflection manner.
The grating area length 6 mm of the fiber grating 4 and the temperature compensation grating 6 is measured, and the central wavelength change range is +/-3 nm.
The temperature compensation fiber grating 6 is positioned at the rear end of the stainless steel shell 1 and is in a free deformation state and used for measuring temperature change. The 4 pairs of measuring fiber gratings and 1 pair of temperature compensating fiber gratings are communicated with the fiber demodulation instrument after the rear end of the sensor is welded with the armored optical cable 7.
And transmitting the deformation of the surrounding rock to the cantilever beam in the test process. Each cantilever beam is provided with 1 measuring fiber grating, and the measuring fiber gratings are positioned in an equal-strength area on the inner surface of the cantilever beam and are used for measuring the surface strain of the cantilever beam. And reading the wavelength changes of each measuring fiber grating and each temperature compensating fiber grating through a fiber demodulator, and further calculating to obtain the deformation of the hole wall and the stress of the surrounding rock.
To verify the accuracy of the invention, the following calibration tests were specifically set:
(1) Cantilever beam deformation-wavelength variation calibration: the deformer is placed on the displacement calibration frame and connected with the optical fiber demodulator. And (3) obtaining the wavelength change of the measured fiber bragg grating under different deformation conditions by applying different deformations to the cantilever beam. As shown in fig. 7, it can be seen from the graph that as the deformation of the loading end of the cantilever beam increases, the wavelength of the grating changes continuously, and the two approaches the linear relationship of u=dλ. Meanwhile, the maximum deformation of the deformation meter reaches 3mm, and the measuring range of the deformation meter is greatly improved compared with that of the conventional deformation meter.
(2) Checking the precision of the sensor:
The first step: and installing a deformation meter. And selecting an isotropic organic glass block with the size of 30cm multiplied by 30cm, wherein a through round hole with the diameter of 38mm is formed in the center of one surface of the organic glass block. The sensor is arranged in the round hole, and the cantilever beam has a certain initial compression amount by adjusting the length of the force transmission cap. The armored optical cable 7 at the rear end of the deformation meter is connected with a demodulator, and the wavelength of each fiber grating is recorded by a computer.
And a second step of: and (5) loading. The plexiglas mass is placed on a rigid servo press and pressure is applied on a plane parallel to the axis of the circular hole. FIG. 8 is a graph showing the wavelength variation of fiber gratings in different orientations with pressure. It can be seen from the figure that the wavelength variation and the pressure variation of the fiber bragg grating in different directions have good linear relation.
And a third step of: and (5) checking and checking. Firstly, checking whether the wavelength changes of two fiber bragg gratings on each pair of cantilever beams are equal. As shown in fig. 9, it can be seen from the figure that the wavelength of two optical fiber gratings in the 0 ° direction is substantially equal, and the other three pairs also have a similar rule. Next, it is checked whether the 4 different azimuth wavelength variations are equal for two pairs, and as can be seen from fig. 10, 0 ° +90° is substantially equal to 45 ° +135°. The test results are reliable as can be shown by the above test.
Fourth step: and (5) calculating stress. According to the wavelength variation of the fiber bragg grating in different directions in fig. 8, according to the relation-u=dλ between the wavelength variation and the cantilever beam deformation (hole wall deformation), the hole wall deformation in different directions can be obtained; then, by adopting the elastic mechanics theory, the known elastic modulus of the organic glass is 2.7GPa, and the Poisson ratio is 0.3, three stress components of the organic glass block in the vertical drilling plane are calculated, as shown in FIG. 12. And comparing the calculated value with the actually implemented pressure value, and calculating to obtain a corresponding error. As can be seen from fig. 12, the maximum error of the measured pressure value of the deformation gauge is about 7%. This proves that the strain gauge has good accuracy.
(3) Long-term stability check of deformation gauge
And different displacements are applied to the two ends of the cantilever beam by adopting a displacement calibration frame, the constant displacement is ensured, and the long-term stability of the deformation meter is detected through the change of the wavelength. As can be seen from fig. 11, the fiber bragg grating wavelength has little change in the period of 14 days, which proves that the strain gauge has good long-term stability and can meet the requirement of long-term monitoring.
Compared with the prior art, the embodiment of the application has the following advantages and effects:
The embodiment of the application is based on the fiber bragg grating sensing technology, and solves the problems of poor anti-interference, easy corrosion, temperature drift and the like of the traditional resistance type surrounding rock stress sensor; the uniform-strength beam is adopted as the grating substrate, so that the application range of the deformation meter is greatly improved; therefore, the difficulty of monitoring the three-dimensional stress of the surrounding rock for a long time in a complex environment is solved.
The embodiment of the application is based on the fiber bragg grating sensing principle, and the fiber bragg grating is welded on a cantilever beam made of spring steel. The structure ensures that the deformation meter has the characteristics of electromagnetic interference resistance, corrosion resistance, high precision, good long-term stability and the like. Meanwhile, the embodiment of the application is applied to the situation that the cantilever beam is a fiber grating substrate, the measuring range of the deformation meter can be adjusted by adjusting the length of the beam, the method can be suitable for long-term monitoring of surrounding rock stress under the conditions of different lithology and different stress levels, and the application range of the deformation meter is improved.
In the embodiment of the application, the cantilever beams adopt equal-strength beams, the fiber gratings are fixed in equal-strength areas of the cantilever beams, and each pair of cantilever beams can move along the radial direction; thereby ensuring that the wavelength changes measured by two fiber gratings corresponding to each pair of cantilever beams are equal, namely. Meanwhile, four pairs of cantilever beams are uniformly distributed in a plane perpendicular to the axial direction of the deformation meter (namely, 0 degrees, 45 degrees, 90 degrees and 135 degrees respectively corresponding to a local coordinate system), and the following relation exists according to the elastic mechanics theory. In the actual monitoring process, the results can be checked and checked by adopting the two relations, unreasonable results can be removed in time, and the monitoring precision is greatly improved.
The above description is only illustrative of the preferred embodiments of the present application and of the principles of the technology employed. It will be appreciated by persons skilled in the art that the scope of the application referred to in the present application is not limited to the specific combinations of the technical features described above, but also covers other technical features formed by any combination of the technical features described above or their equivalents without departing from the inventive concept. Such as the above-mentioned features and the technical features disclosed in the present application (but not limited to) having similar functions are replaced with each other.
Claims (6)
1. A wide-range fiber bragg grating aperture deformer for long-term measurement of surrounding rock stress, comprising:
a housing;
The fixed base material is arranged in the shell and comprises at least one pair of cantilever beams which are axially arranged and symmetrically arranged relative to the axle center of the deformation meter, and a rigid connecting piece which is used for connecting the two cantilever beams and can only rigidly move along the radial direction;
The rigid force transmission piece is arranged on the cantilever beam and provided with a protruding part which faces to the outer side and protrudes out of the shell body to be in contact with the side wall of the drilling hole, and when the side wall of the drilling hole is deformed, the protruding part drives the cantilever beam to generate corresponding deflection deformation;
The grating wavelength of the measuring fiber grating arranged on the cantilever beam changes along with the change of the deflection of the cantilever beam;
the cantilever beam comprises an equal-strength beam region, and the fiber grating is arranged at the equal-strength beam region;
the deformation meter further comprises a fixed support for setting the fixed base material;
The fixed support comprises a support connecting part fixedly connected with the shell and a substrate fixing part used for setting the fixed substrate;
The substrate fixing part is of a cylindrical structure, a through hole for the rigid connecting piece to pass through is formed in the substrate fixing part, the size of the through hole is matched with the size of the section of the rigid connecting piece, and only the rigid connecting piece is allowed to rigidly move along the radial direction.
2. The wide-range fiber bragg grating aperture deformer for long-term measurement of surrounding rock stress according to claim 1, wherein said measuring fiber bragg gratings are arranged in at least four pairs, said four pairs of measuring fiber bragg gratings being uniformly distributed in a circular projection of said housing along a cross section.
3. The long term measured ambient stress wide range fiber grating aperture deformer of claim 1, wherein said cantilever beam is made of spring steel.
4. The long-term measured surrounding rock stress wide-range fiber bragg grating aperture deformer according to claim 1, wherein said fixed support comprises a first fixed support and a second fixed support for fixing a same rigid connection member, said first and second fixed supports are fixedly arranged in said housing, a first via hole is arranged on said first fixed support, a second via hole is arranged on said second fixed support, said first and second via holes are used for penetrating said rigid connection member and allowing only said rigid connection member to rigidly move along a radial direction.
5. The wide-range fiber bragg grating aperture deformer for long-term measurement of surrounding rock stress according to claim 1, wherein said deformer further comprises a temperature compensating fiber bragg grating in a freely deformed state provided at the rear end of said housing.
6. A method of calibrating a wide range fiber grating aperture deformer for long term measurement of surrounding rock stress according to any of claims 1-5, comprising the steps of:
The deformation meter is arranged in a center penetrating round hole of the organic glass block, and the organic glass block is uniform in material quality and isotropy;
applying pressure to the organic glass block, wherein the direction of the pressure is perpendicular to a plane parallel to the axis direction of the round hole, checking whether the wavelength change and the pressure change of the measured fiber bragg grating in different directions are in good linear relation, and if not, checking disqualification by a deformation meter;
Checking whether the wavelength changes of the two corresponding fiber bragg gratings on each pair of cantilever beams are equal, if not, checking disqualification by the deformer;
and checking whether the sum of the wavelength variation values of the two pairs of fiber gratings staggered with each other is equal to the sum of the wavelength variation values of the other two pairs of fiber gratings, and if not, checking disqualification by the deformer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810884334.8A CN108871222B (en) | 2018-08-06 | 2018-08-06 | Wide-range fiber grating aperture deformer and checking method thereof |
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| CN201810884334.8A CN108871222B (en) | 2018-08-06 | 2018-08-06 | Wide-range fiber grating aperture deformer and checking method thereof |
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| CN108871222B true CN108871222B (en) | 2024-09-27 |
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| CN107328370A (en) * | 2017-06-23 | 2017-11-07 | 中国科学院武汉岩土力学研究所 | The fiber grating aperture deformation-sensor of long-term measurement surrouding rock stress |
| CN107725026A (en) * | 2017-09-18 | 2018-02-23 | 山东科技大学 | A kind of ground geologic body testing borehole deformation device and its method of testing |
| CN208688442U (en) * | 2018-08-06 | 2019-04-02 | 中国科学院武汉岩土力学研究所 | A Large Range Fiber Bragg Grating Aperture Deformometer |
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| CN102359765B (en) * | 2011-09-15 | 2013-06-05 | 中国科学院半导体研究所 | Component-type optical fiber drilling deformeter |
| CN103954228A (en) * | 2014-04-30 | 2014-07-30 | 中国科学院半导体研究所 | High-precision component type optical fiber drilling strain gauge |
| CN107462365A (en) * | 2017-06-23 | 2017-12-12 | 山东星盾安防科技有限公司 | A kind of scaling method of fiber grating measuring part |
| CN207540500U (en) * | 2017-12-08 | 2018-06-26 | 深圳伊讯科技有限公司 | A kind of displacement sensor |
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| CN107328370A (en) * | 2017-06-23 | 2017-11-07 | 中国科学院武汉岩土力学研究所 | The fiber grating aperture deformation-sensor of long-term measurement surrouding rock stress |
| CN107725026A (en) * | 2017-09-18 | 2018-02-23 | 山东科技大学 | A kind of ground geologic body testing borehole deformation device and its method of testing |
| CN208688442U (en) * | 2018-08-06 | 2019-04-02 | 中国科学院武汉岩土力学研究所 | A Large Range Fiber Bragg Grating Aperture Deformometer |
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