CN115266344A - Indoor rock mechanical test deformation measurement system and method based on cable sensing technology - Google Patents

Indoor rock mechanical test deformation measurement system and method based on cable sensing technology Download PDF

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CN115266344A
CN115266344A CN202210865960.9A CN202210865960A CN115266344A CN 115266344 A CN115266344 A CN 115266344A CN 202210865960 A CN202210865960 A CN 202210865960A CN 115266344 A CN115266344 A CN 115266344A
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strain
strain sensor
rock sample
cable
coal rock
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赵同彬
王志奇
谭彦
陈玏昕
郭伟耀
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Shandong University of Science and Technology
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Shandong University of Science and Technology
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Priority to PCT/CN2023/097919 priority patent/WO2024016857A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/066—Special adaptations of indicating or recording means with electrical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/20—Investigating strength properties of solid materials by application of mechanical stress by applying steady bending forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0001—Type of application of the stress
    • G01N2203/0003—Steady
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0019—Compressive
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0023—Bending
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075—Strain-stress relations or elastic constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/025—Geometry of the test
    • G01N2203/0252—Monoaxial, i.e. the forces being applied along a single axis of the specimen
    • G—PHYSICS
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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    • G01N2203/02—Details not specific for a particular testing method
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
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    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0676—Force, weight, load, energy, speed or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0682—Spatial dimension, e.g. length, area, angle

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Abstract

The invention provides a deformation measuring system and method for an indoor rock mechanical test based on a cable sensing technology, and relates to the technical field of rock mechanical tests. The system comprises a strain sensor, a coal rock sample, a monitoring device and a computer, wherein the strain sensor comprises a coaxial cable, a connector stitching device and a male connector, and the connector stitching device is arranged on the coaxial cable; the strain sensor determines an assembly combination mode according to the coal rock sample and the parameter to be measured, the monitoring device comprises a vector network analyzer and a terminal load, the computer processes and records the acquired data, the frequency value of the characteristic wave trough corresponding to the reflection point is recorded, the strain value between the reflection points is calculated through data conversion, and then the displacement parameter is determined. The method can monitor the strain and deformation of the surface, the interior and the vicinity of the crack of the sample in the deformation and damage process of the coal rock sample, and has the advantages of flexibility, interference resistance, large measuring range and the like.

Description

Indoor rock mechanical test deformation measurement system and method based on cable sensing technology
Technical Field
The invention relates to the technical field of rock mechanical tests, in particular to an indoor rock mechanical test deformation measurement system and method based on a cable sensing technology.
Background
Strain (displacement) measurement is a measurement instrument commonly used in mining engineering for deformation of coal or coal-like rock samples. In the prior art, two main strain (displacement) measurement modes adopted in an indoor rock mechanical test are divided into a contact measurement mode and a non-contact measurement mode. The contact type measurement mode comprises a strain gauge, a contact type extensometer and a fiber grating sensing technology; non-contact measurement methods include digital image methods, non-contact extensometers, and the like. The measurement mode is widely applied to indoor tests of small and medium-sized coal rocks and similar materials, but still has some defects, such as lower failure strain and smaller measuring range of strain gauges, extensometers and strain sensors; digital image method, non-contact extensometer and other measuring methods are all based on optical principle and are greatly influenced by environmental optical intensity change. In a physical model simulation test with relatively large scale, long test time consumption and complex environment, the defects of easy damage and large time drift of a strain gauge, complex manufacturing of a speckle field, small measuring range of a fiber grating sensing technology and the like are more obvious.
Disclosure of Invention
The invention provides an indoor rock mechanical test deformation measurement system and method based on a cable sensing technology, and the method has the specific technical scheme that the strain and deformation monitoring on the surface, inside and near a crack of a coal rock sample in the deformation damage process of the coal rock sample in a long test time consumption or complex environment is realized.
A deformation measuring system for an indoor rock mechanical test based on a cable sensing technology comprises a strain sensor, a coal rock sample, a monitoring device and a computer, wherein the strain sensor comprises a coaxial cable, joint pressfitting devices and male connector devices, the coaxial cable is provided with a plurality of joint pressfitting devices, and the male connector devices are arranged at two ends of the coaxial cable; the strain sensor is assembled and combined according to the coal rock sample and the parameter to be measured; the monitoring device comprises a vector network analyzer and a terminal load, wherein the terminal load is connected to one end of the strain sensor, and the vector network analyzer is connected to the other end of the strain sensor; the computer processes and records the acquired data, records the frequency value of the characteristic wave trough corresponding to the reflection point, and calculates the strain value between the reflection points through data conversion.
Preferably, the coal rock sample includes a uniaxial compression coal rock sample, a three-point bending test coal rock sample and a similar material model sample.
It is also preferred that the uniaxial compression coal sample is cylindrical and the strain sensor is adhered to the coal sample and spirally wound according to the set wrap angle.
Still preferably, three point bending test coal petrography samples are the cuboid, and strain sensor pastes in the middle part of the coal petrography sample, strain sensor applys the pretightning force.
It is also preferred that the strain sensor is embedded in the similar material model specimen, the strain sensor being deformation-coupled to the similar material model specimen.
A uniaxial compression test method based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, the strain sensor is spirally wound on the coal rock sample, is adhered by epoxy resin and applies pretightening force, and the initial state of the strain sensor keeps 0.05-0.1% of positive strain;
s4, applying an axial load through a testing machine, analyzing monitoring data by using a vector network analyzer and a computer, and determining a strain value of the coaxial cable;
s5, calculating axial deformation of the coal rock sample, wherein when the wrap angle is theta, a relational expression exists:
Figure BDA0003758541250000021
wherein epsilonfIs the strain on the cable, epsilonaIs the axial strain of the coal rock sample, and v is the poisson's ratio of the coal rock sample.
A three-point bending test method based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, fixing the strain sensor on a coal rock sample, applying pretightening force, keeping the strain sensor in a positive strain of 0.05-0.1% in an initial state, adjusting the span of a loading device, and adjusting the position of the rock sample in the center of the loading device;
s4, applying linear load through a testing machine until the test piece is completely broken, stopping loading, and analyzing monitoring data and determining a strain value of the coaxial cable by using a vector network analyzer and a computer;
and S5, calculating and determining a strain value and a displacement value through the frequency shift and the initial interval of the reflection points, and calculating the crack width expansion value of the rock test piece with the prefabricated crack.
It is further preferred that the linear load is loaded at a rate of 0.03mm/min or less and the frequency shift is proportional to the strain.
A similar material simulation test method based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, wrapping the strain sensor with aggregate of a similar material, applying pretightening force, keeping positive strain of 0.05-0.1% in the initial state of the strain sensor, coupling a similar material model sample with the strain sensor, and standing the test model to a stable state;
s4, carrying out analog loading on the similar material model sample, analyzing monitoring data by using a vector network analyzer and a computer, and determining a strain value of the coaxial cable;
and S5, calculating and determining a strain value and a displacement value through the frequency shift and the initial interval of the reflection points, and calculating the strain and displacement field distribution of the physical model of the similar material.
The invention provides a cable sensing technology-based indoor rock mechanical test deformation measurement system and method, which have the beneficial effects that:
(1) The cable strain sensor can record data of the whole deformation and damage process of the rock or coal-like rock sample, and can effectively monitor the self strain and damage of the rock; and aiming at the problems of crack extension measurement and the like of a prefabricated crack sample, the cable sensor can be stuck across the crack, so that related data such as a crack extension value and the like can be measured.
(2) The cable strain sensor can be used for monitoring similar rock materials and the interior of coal rocks, has good ductility, and cannot break; and the coaxial cable can bear larger strain, and can not be out of work because the coal rock mass generates larger deformation.
(3) The strain sensor is interconnected with a computer through a Vector Network Analyzer (VNA), so that the real-time monitoring of strain can be realized, and the spatial resolution of measurement is high; the transmission loss is small, and long-distance transmission can be realized; the error caused by temperature strain measurement can be eliminated, and the measurement precision is improved.
The method for testing and measuring the system also has the advantages of flexibility, interference resistance, high sensitivity and the like, and can continuously monitor the strain and deformation of the tested sample or the physical model in real time.
Drawings
FIG. 1 is a schematic structural view of a strain sensor;
FIG. 2 is a schematic view of a uniaxial compression test axial strain measurement;
FIG. 3 is a graph of axial strain principle;
FIG. 4 is a schematic of strain measurements for a three-point bend test;
FIG. 5 is a schematic view of similar materials coupled to a strain sensor;
FIG. 6 isbase:Sub>A schematic cross-sectional view A-A of FIG. 5;
FIG. 7 is a schematic cross-sectional view B-B of FIG. 5;
FIG. 8 is a schematic illustration of a test deformation measurement of a similar model material;
FIG. 9 is a cross-sectional schematic view of FIG. 8;
in the figure: 1-coal rock sample, 2-coaxial cable, 3-terminal load, 4-connecting cable, 5-male connector, 6-connector pressing device, 7-vector network analyzer, 8-three-point bending tester, 9-pressure head and 10-metal ring sleeve.
Detailed Description
The present invention provides a deformation measuring system and method for indoor rock mechanics tests based on cable sensing technology, and a specific embodiment thereof will be described with reference to fig. 1 to 9.
The utility model provides an indoor rock mechanical test deformation measurement system based on cable sensing technique, includes strain sensor, coal petrography sample, monitoring devices and computer, and strain sensor can be to rock or the data record of class coal petrography sample deformation and destruction overall process, and the coal petrography sample is the coal petrography sample of different indoor rock mechanical test preparation, and monitoring devices goes on strain sensor's data, and the computer calculates and stores the measuring result.
The strain sensor comprises a coaxial cable, a connector stitching device and a male connector, wherein the connector stitching device is arranged on the coaxial cable, and the male connector is arranged at two ends of the coaxial cable. The strain sensor is a distributed strain measurement sensor of a Coaxial Cable Fabry-Perot Interferometer (CCFPI), can monitor mechanical related physical quantities such as displacement, strain, pressure, torque and the like, adopts a Coaxial Cable as a sensing and transmission medium, and has the obvious advantages of being firm and durable, and being capable of realizing distributed and large-deformation measurement.
The strain sensor can be specifically an adhesive or embedded combination according to the assembly combination mode of the coal rock sample and the parameter to be measured. The monitoring device comprises a vector network analyzer and a terminal load, wherein the terminal load is connected to one end of the strain sensor, the vector network analyzer is connected to the other end of the strain sensor, when radio frequency waveforms are transmitted to the coaxial cable, electromagnetic waves can be reflected at four impedance discontinuity points, the four reflected electromagnetic waves generate resonance, and an interference spectrum is formed in a frequency domain. The computer processes and records the acquired data, records the frequency value of the characteristic wave trough corresponding to the reflection point, and calculates the strain value between the reflection points through data conversion.
The coal rock sample comprises a uniaxial compression coal rock sample, a three-point bending test coal rock sample and a similar material model sample. The uniaxial compression coal rock sample is cylindrical, and the strain sensor is adhered to the coal rock sample and spirally wound according to the set wrap angle. The coal rock sample for the three-point bending test is a cuboid, the strain sensor is adhered to the middle of the coal rock sample, and the strain sensor applies pretightening force. The strain sensor is embedded in the similar material model sample, and the strain sensor is coupled with the similar material model sample in a deformation mode. And the sizes of various coal rock samples and the sizes of the strain sensors are adapted to each other, and after the sizes and the matching modes of the coal rock samples are determined, the lengths of the coaxial cables of the strain sensors and the arrangement number of the connector pressfittings are set according to needs.
A uniaxial compression test method based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor.
Wherein, the length of the coaxial cable 21 is 230mm according to the axial length 100mm and the diameter 50mm of the coal rock sample 1. The coaxial cable 21 forms impedance discontinuity at four places by pressing the connector presser 6 with a crimping pliers, the connector presser has a spacing of 22mm, thereby causing reflection of electromagnetic waves to form a fabry-perot interference cavity, and the coaxial cable 2 with the CCFPI cable strain sensor is manufactured, referring to fig. 2. How to evaluate the fabrication quality of the fabry-perot interference cavity. Wherein the aperture of the opening of the crimping pliers is 2.7-3.0mm, the length of the connector presser is 24mm, and the width of the connector presser is 7.9mm.
And S2, connecting the male connector of the strain sensor with a vector network analyzer and a terminal load.
Specifically, the SMA straight male connector 5 is connected to two ends of the cable, and then a Vector Network Analyzer 7 (VNA) and a terminal load 3 with an impedance of 50 Ω are respectively connected to the two ends. When a radio frequency waveform is transmitted to the cable 2, the electromagnetic waves can generate reflected electromagnetic waves at four impedance discontinuity points, and the four reflected electromagnetic waves generate resonance to form an interference pattern in a frequency domain.
S3, the strain sensor is spirally wound on the coal rock sample, is adhered by epoxy resin and applies pretightening force, and the initial state of the strain sensor keeps 0.05-0.1% of positive strain.
Specifically, the coaxial cable 2 with the CCFPI cable strain sensor is spirally wound on the coal rock sample 1 according to a wrap angle of 43 degrees and is bonded on the processed coal rock sample 1 through epoxy resin glue, and when the coaxial cable 2 is bonded on a cylindrical sample, a pre-tightening force of about 0.1kN is applied, so that the initial state of the coaxial cable 2 with the CCFPI cable strain sensor is kept at a positive strain of about 0.05-0.1%.
And S4, applying an axial load through a testing machine, analyzing the monitoring data by using a vector network analyzer and a computer, and determining a strain value of the coaxial cable.
Specifically, an axial load can be applied at a loading rate of 0.03mm/min, the vector network analyzer 7 is started to monitor during loading, waveform storage is performed in a VNA frequency domain mode, and the storage time interval is 20s. And (4) loading until the test piece is completely damaged, stopping loading, stopping data storage and exporting test data. And (4) processing the data to obtain a strain value of the cable.
S5, calculating axial deformation of the coal rock sample, wherein when the wrap angle is theta, a relational expression exists:
Figure BDA0003758541250000051
wherein epsilonfIs the strain on the cable, epsilonaIs the axial strain of the coal rock sample, and v is the poisson's ratio of the coal rock sample.
A three-point bending test method based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor.
According to the length of 130mm, the width of 20mm and the thickness of 50mm of a coal rock sample 1, the length of a coaxial cable 2 of the cable strain sensor with the CCFPI is designed and calculated to be 120m. The coaxial cable 2 forms an impedance discontinuous point at about the center position by pressing the connector presser 6 through the wire crimper to form a Fabry-Perot interference cavity, and the coaxial cable 2 with the CCFPI cable strain sensor is manufactured. With the splice crimpers spaced 20mm apart.
And S2, connecting the male connector of the strain sensor with a vector network analyzer and a terminal load.
The SMA straight male connectors 5 are connected to two ends of the cable, and then a Vector Network Analyzer 7 (VNA) and a terminal load 3 with an impedance of 50 Ω are respectively connected to the two ends. When a radio frequency waveform is transmitted to the cable 2, the electromagnetic wave can generate reflected electromagnetic waves at two impedance discontinuity points, and the two reflected electromagnetic waves generate resonance to form an interference pattern in a frequency domain.
S3, fixing the strain sensor on the coal rock sample, applying pretightening force, keeping the strain sensor in a positive strain of 0.05-0.1% in an initial state, adjusting the span of the loading device, and adjusting the position of the rock sample in the center of the loading device.
The coaxial cable 2 with the CCFPI cable strain sensor is bonded to the processed coal rock sample 1 by epoxy glue, wherein the cable sensor measuring point is arranged at the center of the sample. And the coaxial cable 2 needs to apply a pretightening force of about 0.1kN, so that the initial state of the coaxial cable 2 is kept at a positive strain of about 0.05-0.1%. And adjusting the span of the three-point bending loading device 8 to be 100mm of a design value, placing the test piece on the testing device 8, adjusting the position to enable the test piece to be positioned in the center of the device 8, and adjusting and checking through a vernier caliper.
And S4, applying a linear load through a testing machine until the test piece is completely broken, stopping loading, and analyzing monitoring data and determining a strain value of the coaxial cable by using a vector network analyzer and a computer.
The test is started with the indenter 9 applying a line load. Applying an axial load at a loading rate of 0.03mm/min, starting a vector network analyzer for monitoring while loading, and storing waveforms in a VNA frequency domain mode at a time interval of 20s; and loading until the test piece is completely broken, stopping loading, stopping data storage, and exporting test data.
S5, calculating and determining a strain value and a displacement value through the frequency shift and the initial distance of the reflection points, and calculating the crack width expansion value of the rock test piece with the prefabricated crack. Where the frequency shift is proportional to the strain, as shown in figure 3.
A simulation test method of similar materials based on a cable sensing technology utilizes the indoor rock mechanical test deformation measurement system based on the cable sensing technology, and comprises the following steps:
s1, manufacturing a strain sensor.
The length of coaxial cable 2 with the CCFPI cable strain sensor is designed according to the dimensions of a similar material simulation test. And extruding the connector presser 6 by a wire crimper to form an impedance discontinuous point at the measuring point of the coaxial cable 2 to form a Fabry-Perot interference cavity, thus manufacturing the coaxial cable 2 with the CCFPI cable strain sensor. With the splice crimpers spaced 20mm apart.
And S2, connecting the male connector of the strain sensor with a vector network analyzer and a terminal load.
And (5) carrying out coupling processing on the sensor. The metal lantern ring 10 is adopted to wrap the joint presser 6, the SMA straight male connector 5 and the terminal load 3, so that the protection effect is achieved. Coating epoxy resin adhesive on the coaxial cable 2, and applying a pretightening force of about 0.1kN to the strain sensor with the CCFPI cable to keep the initial state of the cable at a positive strain of about 0.05-0.1%; then the mould is wrapped by the aggregate used by similar materials to ensure the deformation coupling of the mould.
S3, wrapping the strain sensor with aggregate of similar materials, applying pretightening force, keeping positive strain of 0.05-0.1% in the initial state of the strain sensor, coupling a similar material model sample with the strain sensor, and standing the test model to a stable state.
And (4) according to the test content and the measuring point positions, arranging the coaxial cable subjected to coupling treatment and similar materials together. After the similar materials and the cables are laid, the model is placed still for one week, and then the test is started.
And S4, carrying out analog loading on the similar material model sample, and analyzing the monitoring data and determining the strain value of the coaxial cable by using a vector network analyzer and a computer.
After the test formally starts, loading and starting a vector network analyzer for monitoring, and storing the waveform in a VNA frequency domain mode, wherein the storage time interval is 20s; and after the experiment is finished, stopping loading, stopping data storage and exporting test data.
And S5, calculating and determining a strain value and a displacement value through the frequency shift and the initial interval of the reflection points, and calculating the strain and displacement field distribution of the physical model of the similar material.
In the test method, the cable strain sensor can record data of the whole deformation and damage process of the rock or coal-like rock sample, and can effectively monitor the self strain and damage of the rock; aiming at the problems of crack extension measurement and the like of a sample with a prefabricated crack, the cable sensor can be stuck across the crack so as to measure related data such as a crack extension value and the like; in addition, the cable strain sensor can monitor inside similar rock material and the coal rock mass, has fine ductility, and the sensor can not break off, and coaxial cable can also bear great meeting an emergency, can not take place to become invalid because of the great displacement of coal rock mass. The method for testing and measuring the system also has the advantages of flexibility, interference resistance, high sensitivity and the like, and can continuously monitor the strain and displacement of the tested sample or the physical model in real time.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make various changes, modifications, additions and substitutions within the spirit and scope of the present invention.

Claims (9)

1. A deformation measuring system for an indoor rock mechanical test based on a cable sensing technology is characterized by comprising a strain sensor, a coal rock sample, a monitoring device and a computer, wherein the strain sensor comprises a coaxial cable, a connector stitching device and a male connector; the strain sensor is assembled and combined according to the coal rock sample and the parameter to be measured; the monitoring device comprises a vector network analyzer and a terminal load, wherein the terminal load is connected to one end of the strain sensor, and the vector network analyzer is connected to the other end of the strain sensor; the computer processes and records the collected data, records the frequency value of the characteristic wave trough corresponding to the reflection point, and calculates the strain value between the reflection points through data conversion.
2. The system for measuring deformation in indoor rock mechanical test based on cable sensing technology as claimed in claim 1, wherein the coal rock sample comprises uniaxial compression coal rock sample, three-point bending test coal rock sample and similar material model sample.
3. The system for measuring deformation in indoor rock mechanical test based on cable sensing technology as claimed in claim 2, wherein the uniaxial compression coal rock sample is cylindrical, and the strain sensor is adhered on the coal rock sample and spirally wound according to the set wrap angle.
4. The system for measuring deformation in an indoor rock mechanical test based on the cable sensing technology as claimed in claim 2, wherein the three-point bending test coal rock sample is a cuboid, the strain sensor is adhered to the middle of the coal rock sample, and the strain sensor applies a pre-tightening force.
5. The system for measuring deformation in indoor rock mechanical test based on cable sensing technology as claimed in claim 2, characterized in that the strain sensor is buried in a similar material model sample, and the strain sensor is coupled with the similar material model sample in deformation.
6. A uniaxial compression test method based on cable sensing technology, which utilizes the indoor rock mechanical test deformation measurement system based on cable sensing technology as claimed in any one of claims 1 to 3, and is characterized in that the method comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, the strain sensor is spirally wound on the coal rock sample, is adhered by epoxy resin and applies pretightening force, and the initial state of the strain sensor keeps 0.05-0.1% of positive strain;
s4, applying an axial load through a testing machine, analyzing monitoring data by using a vector network analyzer and a computer, and determining a strain value of the coaxial cable;
s5, calculating axial deformation of the coal rock sample, wherein when the wrap angle is theta, a relational expression exists:
Figure FDA0003758541240000011
wherein epsilonfIs the strain on the cable, epsilonaIs the axial strain of the coal rock sample, and v is the poisson's ratio of the coal rock sample.
7. A three-point bending test method based on cable sensing technology, which utilizes the indoor rock mechanical test deformation measurement system based on cable sensing technology as claimed in any one of claims 1, 2 and 4, and is characterized in that the method comprises the following steps:
s1, processing a coal rock sample and manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, fixing the strain sensor on a coal rock sample, applying pretightening force, keeping the strain sensor in a positive strain of 0.05-0.1% in an initial state, adjusting the span of a loading device, and adjusting the position of the rock sample in the center of the loading device;
s4, applying a linear load through a testing machine until the test piece is completely broken, stopping loading, and analyzing monitoring data and determining a strain value of the coaxial cable by using a vector network analyzer and a computer;
and S5, calculating and determining a strain value and a displacement value through the frequency shift and the initial interval of the reflection points, and calculating the crack width expansion value of the rock test piece with the prefabricated crack.
8. A three-point bending test method based on cable sensing technology according to claim 7, wherein the loading rate of the linear load is 0.03mm/min or less, and the frequency shift is proportional to the strain.
9. A similar material simulation test method based on cable sensing technology, which utilizes the indoor rock mechanics test deformation measuring system based on cable sensing technology as claimed in any one of claims 1, 2 and 5, and is characterized by comprising the following steps:
s1, manufacturing a strain sensor;
s2, connecting a male connector of the strain sensor with a vector network analyzer and a terminal load;
s3, wrapping the strain sensor with aggregate of a similar material, applying pretightening force, keeping positive strain of 0.05-0.1% in the initial state of the strain sensor, coupling a similar material model sample with the strain sensor, and standing the test model to a stable state;
s4, carrying out analog loading on the similar material model sample, analyzing monitoring data by using a vector network analyzer and a computer, and determining a strain value of the coaxial cable;
s5, calculating and determining a strain value and a displacement value according to the over-frequency shift and the initial distance of the reflection points, and calculating the strain and displacement field distribution of the physical model of the similar material.
CN202210865960.9A 2022-07-22 2022-07-22 Indoor rock mechanical test deformation measurement system and method based on cable sensing technology Pending CN115266344A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024016857A1 (en) * 2022-07-22 2024-01-25 山东科技大学 System for deformation measurement in indoor rock mechanics test based on cable sensing technology and method

Family Cites Families (7)

* Cited by examiner, † Cited by third party
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US20120143525A1 (en) * 2010-12-03 2012-06-07 Baker Hughes Incorporated Interpretation of Real Time Compaction Monitoring Data Into Tubular Deformation Parameters and 3D Geometry
US9046342B2 (en) * 2011-04-01 2015-06-02 Habsonic, Llc Coaxial cable Bragg grating sensor
CN107121227A (en) * 2017-06-21 2017-09-01 大连理工大学 Intelligent steel strand, preparation method and its monitoring method based on coaxial cable Fabry Perot interference sensing
CN115266345A (en) * 2022-07-22 2022-11-01 山东科技大学 Coal rock deformation damage three-dimensional dynamic test method based on cable sensor
CN115266344A (en) * 2022-07-22 2022-11-01 山东科技大学 Indoor rock mechanical test deformation measurement system and method based on cable sensing technology
CN115265396A (en) * 2022-07-22 2022-11-01 山东科技大学 Anchor rod deformation monitoring structure based on cable sensing and using method
CN115265397A (en) * 2022-07-22 2022-11-01 山东科技大学 Intelligent roof rock stratum monitoring system and method based on CCFPI cable strain sensor

Cited By (1)

* Cited by examiner, † Cited by third party
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WO2024016857A1 (en) * 2022-07-22 2024-01-25 山东科技大学 System for deformation measurement in indoor rock mechanics test based on cable sensing technology and method

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