AU2020100871A4 - A Fiber Bragg Grating Test Device For Internal Three-Dimensional Stress Of Rock - Google Patents
A Fiber Bragg Grating Test Device For Internal Three-Dimensional Stress Of Rock Download PDFInfo
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- AU2020100871A4 AU2020100871A4 AU2020100871A AU2020100871A AU2020100871A4 AU 2020100871 A4 AU2020100871 A4 AU 2020100871A4 AU 2020100871 A AU2020100871 A AU 2020100871A AU 2020100871 A AU2020100871 A AU 2020100871A AU 2020100871 A4 AU2020100871 A4 AU 2020100871A4
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- 239000011435 rock Substances 0.000 title claims abstract description 60
- 238000012360 testing method Methods 0.000 title claims abstract description 27
- 239000000463 material Substances 0.000 claims abstract description 23
- 238000012545 processing Methods 0.000 claims abstract description 7
- 230000003287 optical effect Effects 0.000 claims abstract description 4
- 238000007405 data analysis Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000006378 damage Effects 0.000 abstract description 7
- 238000012544 monitoring process Methods 0.000 abstract description 5
- 230000007774 longterm Effects 0.000 abstract description 4
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000004044 response Effects 0.000 abstract description 4
- 239000000835 fiber Substances 0.000 abstract description 3
- 230000002265 prevention Effects 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 9
- 238000001514 detection method Methods 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- 238000005553 drilling Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000005483 Hooke's law Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 238000009662 stress testing Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000006004 Quartz sand Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/10—Detecting, e.g. by using light barriers
- G01V8/20—Detecting, e.g. by using light barriers using multiple transmitters or receivers
- G01V8/24—Detecting, e.g. by using light barriers using multiple transmitters or receivers using optical fibres
-
- 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
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geophysics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a fiber Bragg grating (FBG) test device for internal three-dimensional
stress of rock, which covers a data processing module composed of a FBG Network
Demodulator, a computer, three FBGs and basis material for installing. The material can
deform with rock, and three FBGs are respectively fixed on the surface of the material along
three-dimensional direction. The three FBGs are all connected to the Demodulator. The
invention can measure the deformation at a level of micro-strain, so it can make a timely
response before rock damages, and realize high-precision measurement to internal
three-dimensional stress of rock. Thus, it can be achieved of long-term and effective
monitoring for large-scale rock engineering, and more beneficial to the disaster prevention.
Descriptions with Drawings
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Description
Descriptions with Drawings
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Descriptions
A fiber Bragg grating test device for internal three-dimensional stress of rock
Technical Field The invention relates to the field of stress testing of rock, in particular to a FBG test device for internal three-dimensional stress of rock.
Background Technology China is one of the countries with frequent natural disasters in the world. Disasters such as coalmine accidents, debris flows and landslides occur frequently, and the economic losses caused are difficult to estimate. The occurrence of many serious accidents is due to the unknowing of the stress state and internal defects of rock mass. It has become one of the nine key mechanical problems for the mechanical science in the development of China in the new century, to timely recognize the representation of mechanical signals from micro to macro in rock and raise an alarm before rock damage. Under external load, the process of the initiation, growth, expansion and convergence of defects in rock leads to the ultimate failure of rock, so the deformation and failure of rock is a process of damage evolution. The internal stress state of rock, especially the three-dimensional stress state after the initial stress state is broken, will play a vital role in the crack initiation, expansion and extension. Therefore, it is one of the most effective means to reduce the occurrence of disasters by monitoring the three-dimensional stress of rock in time and obtaining the crack propagation mechanism.
At present, there are many detecting methods for the occurrence, development and destruction of rock cracks, such as optical detection, CT, acoustic emission, electromagnetic radiation and infrared detection, etc., which can only test the growth and evolution of rock crack and is difficultly to measure the internal three-dimensional stress. Compared with the detection of rock crack, it has not made much progress on the research of internal stress testing of rock, especially for the long-term and effective detection of the three-dimensional stress for large engineering rock mass.
At present, the detection of three-dimensional stress in rock mainly depends on the method of testing the initial stress, such as hydraulic fracturing method which refers to testing the initial stress of rock by drilling holes and injecting high-pressure water to break it, which is only a two-dimensional stress measurement method. It is almost impossible to drill three non-parallel boreholes to determine a three-dimensional stress field, and the accuracy of test results are greatly affected by factors such as the original joint cracks in rock and human experience. The test of the initial stress is essentially different from testing the internal stress under external load: the former only measures the initial stress of rock without external disturbance, and there is no change in the stress state and damage under load; but the latter is mainly to test the change of stress state distribution under external influence such as mining, dynamic change of stress, and the deformation and fracture of rock.
The stress relief method is a measurement with longer development history and a theoretically mature test. Among the various instruments used for stress relief, the hollow inclusion cell is the most used instrument. Its main component includes a hollow cylinder made of steel, copper or other hard metal materials with a pressure sensing element in the center part. When measuring, it needs a drilling hole at the measuring point first, and then squeeze the cylinder into the hole to keep it and the wall in close contact like being welded. Theoretical analysis shows that, for a rigid inclusion cell in an infinite body, when the stress in surrounding rock changes, a uniformly distributed stress field will be generated in the cell. There is a certain proportional relationship between the stress in the cell and the rock mass. Assuming there is stress change along X direction in rock, the stress will also occur along X direction in the cell, as shown in the following formula:
1-v 2{ 1 + 2 1+v+- (1+ v')1-2v') E (1+v')+(1+vX3-4v) E' E'
For the above formula, E, E'represent the elasticity modulus of rock and the cell respectively; V , V represent the Poisson's ratio of rock and the cell respectively. The sensor used by the instrument is the traditional resistance strain gauge, which has shortcomings such as poor anti-interference, durability and long-term stability, and is easily affected by external influences and difficultly adapt to requirements of modern engineering monitoring. Therefore, it is very unrealistic to measure the dynamic stress with the method of testing initial stress, and it is necessary to constantly seek new methods suitable for rock stress and strain detection.
Since the 1990s, FBG has become a new type of reflection filter sensor with wide application prospect and excellent performance, which can realize on-line measurement of structures by sensing small strain through wavelength drifts. This technology is widely used in aerospace, composite materials, concrete structural engineering, electric power engineering and medicine. There are reports about combining FBGs and rockbolts to form testing bolts to monitor the internal deformation of rock mass, or pasting FBGs on the surface of rock specimen for strain or stress test under loading. But no matter what method is used, due to the sensitivity only along axial of FBG, the three-dimensional stress test has never been achieved.
Invention Summary The purpose of the present invention is to provide a testing device for internal three-dimensional stress of rock, which can make a timely and accurate response before the rock damages, and reduce the occurrence of disasters.
The invention adopts the following technical scheme: a FBG test device for internal three-dimensional stress of rock, including a data processing module composed of a FBG Network Demodulator and a computer with connection of output and input end of Demodulator and computer. It also includes a FBG sensing structure, which consists of three FBGs and basis material for installing. The described material deforms with rock, and the described three FBGs are respectively fixed on the surface of the material along three-dimensional direction. The described three FBGs are all connected to the Demodulator.
The described basis material is a cube module, and the three FBGs are respectively fixed on its three adjacent surfaces along three-dimensional direction.
The described basis material is a cylindrical module, and the three FBGs are respectively fixed on its cylindrical surfaces along three-dimensional direction.
The described basis material is a triangular pyramid module, and the three FBGs are respectively fixed on its three adjacent surfaces along three-dimensional direction.
The described basis is a concrete module.
In this invention, three FBGs are fixed on the basis material to form a test structure for three-dimensional stress. It overcomes the disadvantage that FBG is only sensitive to one-way stress, and realize the monitor for internal three-dimensional stress of rock, which is of great significance for obtaining the internal stress variation in mining and the micromechanical behavior before rock collapse. FBG has not only very high accuracy of test, but also many other advantages, such as anti-external radiation, anti-electromagnetic interference and so on. FBG can measure deformation at a level of microstrain, so it can make timely response before rock failure, and realize high precision measurement of internal three-dimensional stress of rock. Thus, it can be achieved of long-term and effective monitoring for large-scale rock engineering, and it is more easier to disaster prevention and its occurrence reduction. The invention is also of great significance for people to explore the deformation mechanism of rock, realize new mine safety monitoring and prediction technology, and reduce natural disasters caused by deformation and instability of rock.
Description with Drawings Figture.1 is a schematic diagram of a cubic FBG sensing structure in this invention;
Figture.2 is a circuit block diagram of the data processing module in this invention;
Figture.3 is a schematic diagram of the cylindrical FBG sensing structure of this invention;
Figture.4 is a schematic diagram of a triangular pyramid FBG sensing structure in this invention.
Detailed Implementation As shown in Figture.1 and Figture.2, in this invention, it is about a FBG testing device for internal three-dimensional stress of rock, which includes a data processing module composed of FBG Network Demodulator and a computer, and a FBG sensing structure. The sensing structure is composed of three FBGs 21, 22, and 23 and the basis material for mounting the gratings. In the implementation, the basis material is the cube module 1, and the three FBGs 21, 22, and 23 are respectively pasted on its three adjacent surfaces along three-dimensional direction with high-strength epoxy resin glue. The three FBGs 21, 22, 23 are all connected to the FBG Network Demodulator, and the Demodulator is connected to the computer through a network cable. The data processing module composed of the Demodulator and the computer is existing devices, and the Demodulator includes a photoelectric conversion module, a data acquisition module, a wavelength calculation module, and a data analysis module. The described cube module 1 in this implementation is a concrete module, which is composed of cement, quartz sand, and water mixed with a mass ratio of 1:1.5:1. According to the theory of material deformation, the concrete module and rock have high degree of similarity in mechanical properties, so it is easy to achieve coordinated deformation and realize high-precision testing; in addition, the cube module 1 can also be composed of other materials, such as high-strength composite fiberglass, etc.
As shown in figure 3, the basis material in this invention can also be a cylinder 3; three FBGs 21, 22, 23 are respectively fixed on its cylindrical surfaces along three-dimensional direction. As shown in figure 4, the basis material can also be a triangular pyramid 4, and three FBGs 21, 22, 23 are respectively fixed on its three adjacent surfaces along three-dimensional direction to measure the three-dimensional stress of rock.
As shown in Figures 1 and 2, when testing with the device of this invention, the FBG sensing structure is embedded into rock by drilling, and fixed by sealing hole with concrete to guarantee it be integrated with rock. Then, the three-dimensional stress state of rock is changed by external loading and in view of this, the three FBGs 21, 22, and 23 generate strain, and the three-dimensional stress can be obtained by the analysis with Hooke's law. Specifically, assuming the three FBGs 21, 22, and 23 as Fx, Fy, and F, respectively, the Fx is parallel to x-axis, so it is only sensitive to stress parallel to x- direction. Similarly, Fy and Fz are only sensitive to stress parallel to y and z axis. When the FBGs 21, 22, and 23 are simultaneously subjected to three-dimensional stress, the F, Fy and Fz respectively sense the stress along the directions x, y and z, resulting in strain which can be tested by FBGs. The Demodulator sends the light signal to FBG in the fiber, and the light that meets the reflection condition is reflected back. The reflected light returns to the Demodulator and is processed into electrical signal. Then, it is transmitted to the computer through data acquisition, wavelength calculation and data analysis module. Through this process, the reflection wavelength drifts can be obtained, and then the strain of FBGs 21, 22, and 23 can also be gotten through data processing, the three-dimensional stress variation can be obtained through the analysis of Hooke's law. When testing the internal deformation of simulated materials, the FBG structure is embedded in during the process of model making. If the FBG sensing structure shown in figure 3 or figure 4 is used, the working principle is the same as the FBG cube structure to obtain three-dimensional stress of rock with mechanical analysis. In view of this, it can be inferred that, by the invention, the timely and accurate response before rock damage can be made, and the occurrence of disasters will be reduced.
Claims (5)
1. A FBG test device for internal three-dimensional stress of rock includes a data processing module composed of a FBG Network Demodulator and a computer. The three FBGs are all connected to the Demodulator. The characteristic of the device is that, it also includes a FBG sensing structure consisting of three FBGs and basis material for fixing gratings. The described material can deform with rock, and the described three FBGs are respectively fixed on the surface of the material along three-dimensional direction. The described three FBGs are all connected to the Demodulator.
2. The FBG test device for internal three-dimensional stress of rock according to claim 1 is characterized in that the basis material is a cube module, and the three FBGs are respectively fixed on its three adjacent surfaces along three-dimensional direction.
3. The FBG test device for internal three-dimensional stress of rock according to claim 1 is characterized in that the basis material is a cylindrical module, and the three FBGs are respectively fixed on its cylindrical surface along three-dimensional direction.
4. The FBG test device for internal three-dimensional stress of rock according to claim 1, is characterized in that the basis material is a triangular pyramid module, and the three FBGs are respectively fixed on its three adjacent surfaces along three-dimensional direction.
5. The FBG test device for internal three-dimensional stress of rock according to claim 2 or 3 or 4, is characterized in that the described basis is a concrete module.
Descriptions with Drawings
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Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2020100871A AU2020100871A4 (en) | 2020-05-28 | 2020-05-28 | A Fiber Bragg Grating Test Device For Internal Three-Dimensional Stress Of Rock |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2020100871A AU2020100871A4 (en) | 2020-05-28 | 2020-05-28 | A Fiber Bragg Grating Test Device For Internal Three-Dimensional Stress Of Rock |
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| Publication Number | Publication Date |
|---|---|
| AU2020100871A4 true AU2020100871A4 (en) | 2020-07-09 |
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| AU2020100871A Ceased AU2020100871A4 (en) | 2020-05-28 | 2020-05-28 | A Fiber Bragg Grating Test Device For Internal Three-Dimensional Stress Of Rock |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113775377A (en) * | 2021-09-08 | 2021-12-10 | 西安科技大学 | BOTDA-based system and method for monitoring pressure relief range of coal rock mass under protective layer mining |
| CN115753475A (en) * | 2022-11-29 | 2023-03-07 | 安徽建筑大学 | Mechanical rock breaking model experiment monitoring system and using method |
| CN116611264A (en) * | 2023-07-14 | 2023-08-18 | 中国矿业大学(北京) | Rock damage evolution model considering initial damage recovery and construction method thereof |
-
2020
- 2020-05-28 AU AU2020100871A patent/AU2020100871A4/en not_active Ceased
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113775377A (en) * | 2021-09-08 | 2021-12-10 | 西安科技大学 | BOTDA-based system and method for monitoring pressure relief range of coal rock mass under protective layer mining |
| CN113775377B (en) * | 2021-09-08 | 2023-03-24 | 西安科技大学 | BOTDA-based system and method for monitoring pressure relief range of coal rock mass under protective layer mining |
| CN115753475A (en) * | 2022-11-29 | 2023-03-07 | 安徽建筑大学 | Mechanical rock breaking model experiment monitoring system and using method |
| CN116611264A (en) * | 2023-07-14 | 2023-08-18 | 中国矿业大学(北京) | Rock damage evolution model considering initial damage recovery and construction method thereof |
| CN116611264B (en) * | 2023-07-14 | 2023-10-13 | 中国矿业大学(北京) | Rock damage evolution model considering initial damage recovery and construction method thereof |
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