Rock deforming and cracking three-dimensional dynamic testing system based on fiber strain sensing

An optical fiber strain, three-dimensional dynamic technology, applied in the direction of applying stable tension/pressure to test the strength of materials, measuring devices, using optical devices, etc. question

Inactive Publication Date: 2009-09-02
SHANDONG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

How to carry out the rock compression-shear composite fracture problem under the simultaneous action of rock compressive stress and shear stress, at present, mathematical mechanics theory analysis and numerical simulation methods are widely used, and some experimental methods are mostly made of similar materials. Approximation and simplification are difficult to achieve the effect of obtaining the deformation and fracture process of real rocks and the evolution law of rock defects, and traditional experiments use strain gauges pasted on real rock specimens for testing, while strain gauges can only be pasted on the rock surface. It is difficult to measure if it goes deep into the rock, and at the same time, the laying effect of the strain gauge on the rock and the anti-interference effect are worse than that of the optical fiber strain sensor. The optical fiber strain sensor mainly refers to the fiber grating sensor and the long period grating sensor in this design. Literature (Underground Space and Engineering Journal, Volume III, No. 6, December 2007) used optical fiber sensing to measure the surface strain of rock specimens of similar materials, but they used bare fiber gratings embedded in the plane model of similar simulation materials, There are also some materials that embed fiber grating sensors in reinforced concrete specimens, or paste them on the surface of rock specimens of different shapes to test unidirectional strain.
Due to the large difference between the rock test piece and the real rock test, they can only obtain approximate data of the rock. If they want to obtain the three-dimensional fracture dynamic process of the rock, they can obtain the real experimental data of the rock under triaxial pressure, and construct the rock visually. image of the rupture process, it is not possible to complete

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  • Rock deforming and cracking three-dimensional dynamic testing system based on fiber strain sensing
  • Rock deforming and cracking three-dimensional dynamic testing system based on fiber strain sensing
  • Rock deforming and cracking three-dimensional dynamic testing system based on fiber strain sensing

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Embodiment 1

[0020] Example 1: figure 1 Among them, the test piece 1 is cylindrical, and its outer surface and end surface are respectively provided with a number of micro-holes 8, and the inner wall, outer surface and end surface of the cylinder of the test piece 1 are also provided with a number of long micro-grooves 9, and the fiber grating sensor 2 are respectively laid in the microhole 8 and the long micro groove 9, and evenly arranged on the inner surface of the cylinder of the test piece 1; the fiber grating sensor 2 arranged on the outer surface and end surface of the test piece 1 is sealed and Fixed to ensure the effective coupling between the fiber grating sensor 2 and the surface of the rock specimen 1, the fiber grating sensor 2 is connected to the optical switch 4 through the optical fiber 3, and the optical switch 4 is connected to the optical fiber demodulation instrument 5. The fiber grating sensor 2 in the microhole 8 is mainly used to test the strain change in the directi...

Embodiment 2

[0021] Embodiment 2: as figure 2 As shown, the test piece 1 is cylindrical, and the outer surface and end surface of the test piece 1 are provided with a number of micropores 8, and the inner wall, outer surface and end surface of the test piece 1 are provided with a number of long micro-grooves 9, and the long-period The grating 6 is laid on the inner surface of the cylinder and in the microholes 8 and elongated micro-grooves 9 on the inner wall, outer surface and end face of the cylinder. One end of the long-period grating 6 is a broadband light source, and the other end is connected to a spectrum analyzer 7 for Analyze the transmission spectrum of a long period grating. The long-period grating 6 in the microhole 8 is mainly used to test the strain change in the direction of the internal horizontal (that is, the X and Y directions); To test the strain change in the vertical (Z direction), the long-period grating 6 in the long micro-groove 9 on the end face is mainly used t...

Embodiment 3

[0022] Embodiment 3: The test piece 1 is square, and the outside of the test piece 1 is provided with several microholes 8 and some long micro-grooves 9, and the long-period grating 6 is laid in the microholes 8 and the long-strip micro-grooves 9, and the long-period grating One end of 6 is a broadband light source, and the other end is connected to a spectrum analyzer 7 for analyzing the transmission spectrum of the long-period grating.

[0023] In the present invention image 3 Indicates the direction of the pressure exerted by the triaxial press on the test piece, the test piece is placed in a sealed pressure chamber, and the upper and lower ends of the test piece are under pressure σ z , the inside of the test piece is filled with high-pressure oil and sealed to cause an outward pressure σ inside the test piece rl , after the outer surface of the specimen is sealed by the external high-pressure oil, an inward pressure σ is generated ro .

[0024] Figure 4 It is a proc...

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Abstract

The invention relates to a rock deforming and cracking three-dimensional dynamic testing system based on fiber strain sensing, which comprises a testing piece, wherein the testing piece is laid with a fiber sensor encapsulated with a plurality of testing strains; the fiber sensor is connected with a signal demodulation processing device through a connecting fiber; and demodulated data signals can build three-dimensional testing data of the testing piece and can form a three-dimensional dynamic strain field of the testing piece after interpolation. The system can effectively lay out the fiber sensor inside and on the surface of the real rock testing piece under the pressure of a three-axis presser, enters the rock inside to detect the rock dynamic strain under the premise of not influencing the rock structure and the stress, and can really test the rock dynamic cracking process to obtain the crack initial and expended spatial positions inside the testing piece. The system continuously monitors the generation and expansion of tiny cracks inside brittle materials under the loading action in real time at the same time, and can be widely applied to researching cracking instability mechanisms of materials, such as rocks, concrete and the like.

Description

technical field [0001] The invention relates to a dynamic testing device for rock deformation and fracture, in particular to a three-dimensional dynamic testing system for rock deformation and fracture based on optical fiber strain sensing. Background technique [0002] The deformation and fracture of rock is an important mechanical property of rock. Rock is an anisotropic medium containing initial defects such as pores, cracks and microstructure planes. In the study of rock engineering mechanics, except for a small number of deformation and stress that can be simplified to a two-dimensional model of a plane problem or an axisymmetric problem for processing, due to the existence of non-uniformity in rock and rock mass, asymmetric damage is easy to occur . Once the breaking of asymmetry is involved, almost all 2D breaking problems become 3D breaking problems. [0003] The problem of rock fracture and instability has always been a hot and difficult point in the research of r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16G01N3/08
Inventor 蒋奇李术才李树忱
Owner SHANDONG UNIV
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