WO2024016857A1 - 基于电缆传感技术的室内岩石力学试验变形测量系统及方法 - Google Patents

基于电缆传感技术的室内岩石力学试验变形测量系统及方法 Download PDF

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WO2024016857A1
WO2024016857A1 PCT/CN2023/097919 CN2023097919W WO2024016857A1 WO 2024016857 A1 WO2024016857 A1 WO 2024016857A1 CN 2023097919 W CN2023097919 W CN 2023097919W WO 2024016857 A1 WO2024016857 A1 WO 2024016857A1
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strain
coal
strain sensor
rock
cable
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French (fr)
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赵同彬
王志奇
谭彦
陈玏昕
郭伟耀
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山东科技大学
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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
    • 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
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0266—Cylindrical specimens
    • 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
    • G01N2203/0676—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

Definitions

  • the invention relates to the technical field of rock mechanics testing, and in particular to an indoor rock mechanics testing deformation measurement system and method based on cable sensing technology.
  • Strain (displacement) measurement is a method commonly used in mining engineering to measure the deformation of coal rock or coal-like rock samples.
  • contact measurement methods include strain gauges, contact extensometers and fiber grating sensing technology; non-contact measurement methods include digital image methods, non-contact extensometers, etc.
  • the above measurement methods have been widely used in indoor and medium-scale coal, rock and similar material tests, but there are still some shortcomings.
  • strain gauges For example, the failure strains of strain gauges, extensometers and equal strain sensors are low and the range is small; digital images Measurement methods such as the method and non-contact extensometer are all based on optical principles and are greatly affected by changes in environmental optical intensity.
  • shortcomings such as easy damage of strain gauges, large time drift, complex speckle field production, and small range of fiber Bragg grating sensing technology are more obvious.
  • the present invention provides An indoor rock mechanics test deformation measurement system and method based on cable sensing technology is proposed.
  • the specific technical scheme of this method is as follows.
  • An indoor rock mechanics test deformation measurement system based on cable sensing technology, including a strain sensor, a coal and rock sample, a monitoring device and a computer.
  • the strain sensor includes a coaxial cable, a joint press and a male connector. Multiple joint presses are arranged on the axial cable, and male connectors are provided at both ends of the coaxial cable; the strain sensor is assembled and combined according to the coal and rock sample and the parameters to be measured; the monitoring device includes a vector network analyzer and Terminal load, 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 reflection point through data conversion strain values between.
  • the coal and rock samples include uniaxial compression coal and rock samples, three-point bending test coal and rock samples and similar material model samples.
  • the uniaxial compression coal and rock sample is cylindrical, and the strain sensor is attached to the coal and rock sample and spirally wound according to the set wrap angle.
  • the three-point bending test coal and rock sample is in the shape of a rectangular parallelepiped, the strain sensor is attached to the middle of the coal and rock sample, and the strain sensor applies a pre-tightening force.
  • the strain sensor is embedded in a similar material model specimen, and the strain sensor is coupled to the deformation of the similar material model specimen.
  • a uniaxial compression test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • the strain sensor is spirally wound and arranged on the coal and rock sample, adhered through epoxy resin and applied pre-tightening force.
  • the initial state of the strain sensor maintains a positive strain of 0.05%-0.1%;
  • a three-point bending test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • the loading rate of the linear load is less than or equal to 0.03 mm/min, and the frequency shift is proportional to the strain.
  • a similar material simulation test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • Cable strain sensors can record data on the entire process of deformation and damage of rock or coal-like rock samples, and can effectively monitor the strain and damage of the rock itself; and for issues such as crack expansion measurement of prefabricated cracked samples, cable sensors can span Cracks are pasted to measure crack expansion values and other related data.
  • the cable strain sensor can be used for monitoring in rock-like materials and inside coal and rock. It has good ductility and the sensor will not break; and the coaxial cable can withstand large strains and will not be caused by the coal and rock mass. Failure occurs due to large deformation.
  • the strain sensor is interconnected with the computer through a vector network analyzer (VNA), which can realize real-time monitoring of strain, and the spatial resolution of the measurement is high; the transmission loss is small, and long-distance transmission can be achieved; the temperature-related strain measurement problems can be eliminated error and improve the accuracy of measurement.
  • VNA vector network analyzer
  • the system's experimental measurement method also has the advantages of flexibility, anti-interference, and high sensitivity. At the same time, it can continuously and real-time monitor the strain and deformation of the tested sample or physical model.
  • Figure 1 is a schematic structural diagram of the strain sensor
  • Figure 2 is a schematic diagram of axial strain measurement in uniaxial compression test
  • Figure 3 is the axial strain principle curve diagram
  • Figure 4 is a schematic diagram of strain measurement in a three-point bending test
  • Figure 5 is a schematic diagram of the coupling method between similar materials and strain sensors
  • Figure 6 is a schematic cross-sectional view of A-A in Figure 5;
  • Figure 7 is a schematic cross-sectional view of B-B in Figure 5;
  • Figure 8 is a schematic diagram of experimental deformation measurement of similar model materials
  • Figure 9 is a schematic cross-sectional view of Figure 8.
  • An indoor rock mechanics test deformation measurement system based on cable sensing technology, including strain sensors, coal and rock samples, monitoring devices and computers.
  • the strain sensors can record data on the entire process of deformation and damage of rock or coal-like rock samples. Coal and rock samples are produced for different indoor rock mechanics tests.
  • the monitoring device performs the data from the strain sensor, and the computer calculates and stores the measurement results.
  • the strain sensor includes a coaxial cable, a joint press and a male connector. Multiple joint presses are arranged on the coaxial cable, and male connectors are provided at both ends of the coaxial cable.
  • the strain sensor is specifically a Coaxial Cable Fabry-Perot Interferometer (CCFPI) distributed strain measurement sensor that can monitor mechanically related physical quantities such as displacement, strain, pressure, and torque. Its measurement
  • CCFPI Coaxial Cable Fabry-Perot Interferometer
  • the strain sensor is assembled and combined according to the coal rock sample and the parameters to be measured. Specifically, it can be a combination of adhesive or embedded.
  • the monitoring device includes a vector network analyzer and a terminal load.
  • 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 radio frequency waveform is transmitted to the coaxial cable, the electromagnetic wave is detected at four impedance discontinuous points. Reflected electromagnetic waves will be generated at , and the four reflected electromagnetic waves will resonate and form an interference pattern in the frequency domain.
  • the computer processes and records the collected data, records the frequency values of the characteristic wave troughs corresponding to the reflection points, and calculates the strain values between the reflection points through data conversion.
  • Coal and rock samples include uniaxial compression coal and rock samples, three-point bending test coal and rock samples and similar material model samples.
  • the uniaxial compression coal and rock sample is cylindrical, and the strain sensor is attached to the coal and rock sample and spirally wound according to the set wrapping angle.
  • the coal and rock sample in the three-point bending test is in the shape of a rectangular parallelepiped.
  • the strain sensor is attached to the middle of the coal and rock sample, and the strain sensor applies a pre-tightening force.
  • the strain sensor is embedded in a similar material model specimen, and the strain sensor is coupled with the deformation of the similar material model specimen.
  • the sizes of various types of coal and rock samples are compatible with the sizes of strain sensors. After determining the size and matching method of coal and rock samples, the length of the coaxial cable of the strain sensor and the number of joint presses can be set as needed.
  • a uniaxial compression test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • the length of the coaxial cable 21 is designed and calculated to be 230 mm.
  • the spacing between the joint presses is 22mm, which causes the reflection of electromagnetic waves to form a Fabry-Perot interference cavity, and a band is made.
  • Coaxial cable 2 with CCFPI cable strain sensor refer to Figure 2. How to evaluate the production quality of Fabry-Perot interference cavity.
  • the opening diameter of the crimping pliers is 2.7-3.0mm
  • the length of the connector crimper is 24mm
  • the width is 7.9mm.
  • VNA Vector Network Analyzer
  • the strain sensor is spirally wound and arranged on the coal and rock sample. It is adhered with epoxy resin and a pre-tightening force is applied. The initial state of the strain sensor maintains a positive strain of 0.05%-0.1%.
  • the coaxial cable 2 with the CCFPI cable strain sensor is spirally wound on the coal rock sample 1 at a 43° wrapping angle, and is bonded to the processed coal rock sample 1 through epoxy resin glue.
  • a pre-tightening force of about 0.1kN should be applied to keep the initial state of the coaxial cable 2 with the CCFPI cable strain sensor at a positive strain of approximately 0.05%-0.1%.
  • the axial load can be applied at a loading rate of 0.03mm/min, and the vector network analyzer 7 can be started for monitoring while loading, and the waveform can be saved in the VNA frequency domain mode with a saving time interval of 20s. Load until the specimen is completely destroyed, stop loading, stop data saving, and export test data. Post-process the data to obtain the strain value of the cable itself.
  • a three-point bending test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • the length of coaxial cable 2 with CCFPI cable strain sensor is designed and calculated to be 120m.
  • the coaxial cable 2 forms an impedance discontinuity point at approximately the center position by squeezing the joint crimping device 6 with a crimping plier, forming a Fabry-Perot interference cavity, and producing the coaxial cable 2 with a CCFPI cable strain sensor.
  • the spacing between joint presses is 20mm.
  • VNA Vector Network Analyzer
  • the coaxial cable 2 with the CCFPI cable strain sensor is bonded to the processed coal and rock sample 1 through epoxy resin glue, in which the cable sensor measuring point is located in the center of the sample. And a pre-tightening force of about 0.1kN is applied to the coaxial cable 2 to maintain the initial state of the coaxial cable 2 at a positive strain of about 0.05%-0.1%. Adjust the span of the three-point bending loading device 8 to the design value of 100mm, place the specimen on the testing device 8, adjust the position so that the specimen is located in the center of the device 8, and adjust and check with the vernier caliper.
  • the indenter 9 applies line load. Apply axial load at a loading rate of 0.03mm/min, start the vector network analyzer monitoring while loading, and save the waveform in VNA frequency domain mode, with a saving time interval of 20s; load until the specimen is completely broken, stop loading, and stop data saving. , export test data.
  • a similar material simulation test method based on cable sensing technology using the above-mentioned indoor rock mechanics test deformation measurement system based on cable sensing technology, the steps include:
  • the coaxial cable 2 length with CCFPI cable strain sensor based on the dimensions of similar material simulation tests.
  • the crimping pliers are used to squeeze the joint presser 6, so that the coaxial cable 2 forms an impedance discontinuity point at the measuring point to form a Fabry-Perot interference cavity, and the coaxial cable 2 with a CCFPI cable strain sensor is manufactured.
  • the spacing between joint presses is 20mm.
  • the metal ferrule 10 is used to wrap the connector press 6, the SMA straight male connector 5 and the terminal load 3 for protection. Apply epoxy resin glue on the coaxial cable 2, and apply a pre-tightening force of about 0.1kN to the CCFPI cable strain sensor to keep the initial state of the cable at about 0.05%-0.1% positive strain; then use similar materials The aggregate used is wrapped to ensure the deformation coupling of the model.
  • the coupled coaxial cables are laid together with similar materials. After laying out similar materials and cables, let the model stand for a week before starting the test.
  • test After the test officially starts, load and start the vector network analyzer monitoring at the same time, and save the waveform in the VNA frequency domain mode with a saving time interval of 20s; after the experiment ends, stop loading, stop data saving, and export the test data.
  • the cable strain sensor can record data on the entire process of deformation and damage of rock or coal-like rock samples, and can effectively monitor the strain and damage of the rock itself; and for issues such as crack expansion measurement of prefabricated cracked samples, Cable sensors can be pasted across cracks to measure crack expansion values and other related data; in addition, cable strain sensors can be used for monitoring in rock-like materials and inside coal and rock masses. They have good ductility and the sensors will not break and are coaxial. The cable can also withstand large strains and will not fail due to large displacements of coal and rock masses.
  • the system's experimental measurement method also has the advantages of flexibility, anti-interference, and high sensitivity. At the same time, it can continuously and real-time monitor the strain and displacement of the tested sample or physical model.

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Abstract

一种基于电缆传感技术的室内岩石力学试验变形测量系统及方法，涉及岩石力学试验技术领域。该系统包括应变传感器、煤岩试样（1）、监测装置和计算机，应变传感器包括同轴电缆（2）、接头压合器（6）和公头连接器（5），同轴电缆（2）上布置接头压合器（6）；应变传感器根据煤岩试样（1）和待测参数确定装配组合方式，监测装置包括矢量网络分析仪（7）和终端负载（3），计算机对采集数据进行处理和记录，记录反射点对应的特征波谷的频率值，通过数据转换计算反射点之间的应变值，进而确定位移参数。该方法可以监测煤岩试样（1）变形破坏过程中试样表面、内部及裂隙附近的应变及变形，具有可弯曲、抗干扰、量程大等优点。

Description

基于电缆传感技术的室内岩石力学试验变形测量系统及方法 技术领域
本发明涉及岩石力学试验技术领域，尤其是一种基于电缆传感技术的室内岩石力学试验变形测量系统及方法。
 背景技术
应变（位移）测量是一种采矿工程中常用于煤岩或类煤岩试样变形的测量手段。现有技术中，室内岩石力学试验中所采用的应变（位移）测量方式主要有两种，分为接触式测量和非接触式测量方式。其中，接触式测量方式包括应变片、接触式引伸计和光纤光栅传感技术；非接触式测量方式包括数字图像法、非接触式引伸计等。以上测量方式在室内中小尺度煤岩及相似材料试验中得到了较为广泛的应用，但仍然存在一些不足，例如，应变片、引伸计和等应变传感器的失效应变较低，量程较小；数字图像法、非接触式引伸计等测量方法均是基于光学原理，受环境光学强度变化影响较大。在尺度相对较大、试验耗时长，环境复杂的物理模型模拟试验中，应变片易损坏、时漂大，以及散斑场制作复杂及光纤光栅传感技术量程小等不足更加明显。
 技术解决方案
为提高室内岩石力学试验变形测量系统的量程以及抗干扰能力，实现试验耗时长或复杂环境下，煤岩试样变形破坏过程中试样表面、内部及裂隙附近的应变和变形监测，本发明提供了一种基于电缆传感技术的室内岩石力学试验变形测量系统及方法，该方法具体技术方案如下。
一种基于电缆传感技术的室内岩石力学试验变形测量系统，包括应变传感器、煤岩试样、监测装置和计算机，所述应变传感器包括同轴电缆、接头压合器和公头连接器，同轴电缆上布置有多个接头压合器，同轴电缆两端设置公头连接器；所述应变传感器根据煤岩试样和待测参数装配组合方式；所述监测装置包括矢量网络分析仪和终端负载，终端负载接入应变传感器的一端，矢量网络分析仪接入应变传感器的另一端；计算机对采集数据进行处理和记录，记录反射点对应的特征波谷的频率值，通过数据转换计算反射点之间的应变值。
优选的是，所述煤岩试样包括单轴压缩煤岩试样、三点弯曲试验煤岩试样和相似材料模型试样。
还优选的是，单轴压缩煤岩试样呈圆柱形，应变传感器黏贴在煤岩试样上并按照设置的包角螺旋缠绕。
还优选的是，三点弯曲试验煤岩试样呈长方体，应变传感器黏贴在煤岩试样中部，所述应变传感器施加预紧力。
还优选的是，应变传感器埋设在相似材料模型试样中，应变传感器与相似材料模型试样变形相耦合。
一种基于电缆传感技术的单轴压缩试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.加工煤岩试样，制作应变传感器；
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
S3.应变传感器螺旋缠绕布置在煤岩试样上，通过环氧树脂黏贴并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变；
S4.通过试验机施加轴向载荷，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
S5.计算煤岩试样发生轴向变形，包角为θ时，存在关系式： 其中， ε f是电缆上的应变， ε a是煤岩试样的轴向应变， v是煤岩试样的泊松比。
一种基于电缆传感技术的三点弯曲试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.加工煤岩试样，制作应变传感器；
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
S3.将应变传感器固定煤岩试样上，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，调整加载装置跨距，调整岩石试件位于加载装置的中心位置；
S4.通过试验机施加线性载荷，直至试件完全断裂停止加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
S5.通过频移以及反射点初始间距，计算确定应变值及位移值，推算预制裂隙的岩石试件裂隙宽度扩展值。
进一步优选的是，线性载荷的加载速率小于等于0.03mm/min，所述频移与应变呈正比。
一种基于电缆传感技术的相似材料模拟试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.制作应变传感器；
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
S3.将应变传感器以相似材料的骨料包裹，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，相似材料模型试样与应变传感器耦合，静置试验模型至稳定状态；
S4.对相似材料模型试样进行模拟加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
S5.通过频移及反射点初始间距，计算确定应变值及位移值，推算相似材料物理模型的应变及位移场分布。
 有益效果
本发明提供的一种基于电缆传感技术的室内岩石力学试验变形测量系统及方法有益效果是：
（1）电缆应变传感器可以对岩石或类煤岩试样变形破坏全过程的数据记录，能够有效地监测岩石自身应变及损伤；并且针对预制裂隙试样的裂隙扩展测量等问题，电缆传感器可以跨裂隙粘贴，从而测量裂隙扩展值等相关数据。
（2）电缆应变传感器可以在类岩石相似材料及煤岩内部进行监测，具有很好的延展性，传感器不会发生断裂；并且同轴电缆能够承受较大的应变，不会因为煤岩体产生较大变形而发生失效。
（3）应变传感器通过矢量网络分析仪（VNA）与计算机互联，可以实现应变的实时监测，测量的空间分辨率高；传输损耗小，可以实现远距离传输；可以消除温度对应变测量带来的误差，提高测量的精度。
该系统进行试验测量的方法还具有可弯曲、抗干扰、灵敏度高等优点，同时其可连续、实时地监测被测试样或物理模型的应变及变形。
 附图说明
图1是应变传感器的结构示意图；
图2是单轴压缩试验轴向应变测量示意图；
图3是轴向应变原理曲线图；
图4是三点弯曲试验应变测量示意图；
图5是相似材料与应变传感器的耦合方式示意图；
图6是图5的A-A截面示意图；
图7是图5的B-B截面示意图；
图8是相似模型材料的试验变形测量示意图；
图9是图8的截面示意图；
图中：1-煤岩试样，2-同轴电缆，3-终端负载，4-连接电缆，5-公头连接器，6-接头压合器，7-矢量网络分析仪，8-三点弯曲试验机，9-压头，10-金属环套。
 本发明的实施方式
结合图1至图9所示，对本发明提供的一种基于电缆传感技术的室内岩石力学试验变形测量系统及方法的具体实施方式进行说明。
一种基于电缆传感技术的室内岩石力学试验变形测量系统，包括应变传感器、煤岩试样、监测装置和计算机，应变传感器可以对岩石或类煤岩试样变形及破坏全过程的数据记录，煤岩试样为不同室内岩石力学试验而制作的煤岩试样，监测装置对应变传感器的数据进行，计算机对测量结果进行计算和存储。
其中，应变传感器包括同轴电缆、接头压合器和公头连接器，同轴电缆上布置有多个接头压合器，同轴电缆两端设置公头连接器。应变传感器具体为同轴电缆法布里-珀罗干涉仪（Coaxial Cable Fabry－Perot Interferometer，CCFPI）的分布式应变测量传感器能够实现对位移、应变、压力及扭矩等力学相关物理量的监测，其测量原理是以同轴电缆作为感应和传输介质，具有结实耐用、可实现分布式和大变形测量的显优点。
应变传感器根据煤岩试样和待测参数装配组合方式，具体可以是黏贴或嵌入式的组合。监测装置包括矢量网络分析仪和终端负载，终端负载接入应变传感器的一端，矢量网络分析仪接入应变传感器的另一端，当射频波形传输到同轴电缆时，电磁波在四个阻抗不连续点处会产生反射电磁波，四个反射电磁波产生共振，在频域内形成干扰图谱。计算机对采集数据进行处理和记录，记录反射点对应的特征波谷的频率值，通过数据转换计算反射点之间的应变值。
煤岩试样包括单轴压缩煤岩试样、三点弯曲试验煤岩试样和相似材料模型试样。单轴压缩煤岩试样呈圆柱形，应变传感器黏贴在煤岩试样上并按照设置的包角螺旋缠绕。三点弯曲试验煤岩试样呈长方体，应变传感器黏贴在煤岩试样中部，所述应变传感器施加预紧力。应变传感器埋设在相似材料模型试样中，应变传感器与相似材料模型试样变形相耦合。并且各类煤岩试样的尺寸与应变传感器的尺寸相互适应，确定煤岩试样的尺寸和配合方式后，根据需要设置应变传感器同轴电缆的长度以及接头压合器的布置数量。
一种基于电缆传感技术的单轴压缩试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.加工煤岩试样，制作应变传感器。
其中，根据煤岩试样1的轴长100mm和直径50mm，设计计算同轴电缆21长度为230mm。通过压线钳挤压接头压合器6使同轴电缆21在这四处形成阻抗不连续点，接头压合器间距22mm，从而引起电磁波的反射构成法布里-珀罗干涉腔，制成带有CCFPI电缆应变传感器的同轴电缆2，参考附图2。如何评价法布里-珀罗干涉腔的制作质量。其中，压线钳开口孔径在2.7-3.0mm，接头压合器长度为24mm，宽度为7.9mm。
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连。
具体的是，将SMA直型公头连接器5连接在电缆两端，然后再在两端分别接入矢量网络分析仪7（Vector Network Analyzer，VNA）和阻抗为50 Ω终端负载3。当射频波形传输到电缆2时，电磁波在四个阻抗不连续点处会产生反射电磁波，四个反射电磁波产生共振，在频域内形成干扰图谱。
S3.应变传感器螺旋缠绕布置在煤岩试样上，通过环氧树脂黏贴并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变。
具体的是，带有CCFPI电缆应变传感器的同轴电缆2按照43°包角螺旋缠绕于煤岩试样1上，并通过环氧树脂胶粘结在经过加工的煤岩试样1上，同轴电缆2在粘贴在圆柱形试样上时，要施加0.1kN左右的预紧力，使带有CCFPI电缆应变传感器同轴电缆2的初始状态保持在大约0.05%-0.1%的正应变。
S4.通过试验机施加轴向载荷，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值。
具体可以按加载速率0.03mm/min施加轴向荷载，加载同时启动矢量网络分析仪7监测，并进行VNA频域模式下进行波形保存，保存时间间隔20s。加载至试件完全破坏，停止加载，停止数据保存，导出试验数据。后处理数据得到电缆本身的应变值。
S5.计算煤岩试样发生轴向变形，包角为 θ时，存在关系式： 其中， ε f是电缆上的应变， ε a是煤岩试样的轴向应变， v是煤岩试样的泊松比。
一种基于电缆传感技术的三点弯曲试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.加工煤岩试样，制作应变传感器。
根据煤岩试样1的长130mm、宽20mm、厚50mm，设计计算带有CCFPI电缆应变传感器有同轴电缆2长度为120m。通过压线钳挤压接头压合器6使同轴电缆2在约中心位置处形成阻抗不连续点，构成法布里-珀罗干涉腔，制成带有CCFPI电缆应变传感器的同轴电缆2。其中接头压合器间距20mm。
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连。
将SMA直型公头连接器5连接在电缆两端，然后再在两端分别接入矢量网络分析仪7（Vector Network Analyzer，VNA）和阻抗为50 Ω终端负载3。当射频波形传输到电缆2时，电磁波在两个阻抗不连续点处会产生反射电磁波，两个反射电磁波产生共振，在频域内形成干扰图谱。
S3.将应变传感器固定煤岩试样上，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，调整加载装置跨距，调整岩石试件位于加载装置的中心位置。
带有CCFPI电缆应变传感器的同轴电缆2通过环氧树脂胶粘结在经过加工的煤岩试样1上，其中电缆传感器测点布置位于试样中心位置。并且同轴电缆2要施加0.1kN左右的预紧力，使同轴电缆2的初始状态保持在大约0.05%-0.1%的正应变。调整三点弯曲加载装置8跨距为设计值100mm，将试件置于试验装置8上，调整位置使试件位于装置8正中心，通过游标卡尺调整校核。
S4.通过试验机施加线性载荷，直至试件完全断裂停止加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值。
开始试验，压头9施加线荷载。按加载速率0.03mm/min施加轴向荷载，加载同时启动矢量网络分析仪监测，并进行VNA频域模式下进行波形保存，保存时间间隔20s；加载至试件完全断裂，停止加载，停止数据保存，导出试验数据。
S5.通过频移以及反射点初始间距，计算确定应变值及位移值，推算预制裂隙的岩石试件裂隙宽度扩展值。其中频移与应变呈正比，如图3所示。
一种基于电缆传感技术的相似材料模拟试验方法，利用上述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，步骤包括：
S1.制作应变传感器。
根据相似材料模拟试验的尺寸设计带有CCFPI电缆应变传感器的同轴电缆2长度。通过压线钳挤压接头压合器6，使同轴电缆2在测点处形成阻抗不连续点，构成法布里-珀罗干涉腔，制成带有CCFPI电缆应变传感器的同轴电缆2。其中接头压合器间距20mm。
S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连。
传感器制作耦合处理。采用金属套环10包裹接头压合器6、SMA直型公头连接器5及终端负载3，起到保护作用。在同轴电缆2上涂抹环氧树脂胶，带有CCFPI电缆应变传感器要施加0.1kN左右的预紧力，使电缆的初始状态保持在大约0.05%-0.1%的正应变；然后用与相似材料所用的骨料包裹，保证模型的变形耦合性。
S3.将应变传感器以相似材料的骨料包裹，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，相似材料模型试样与应变传感器耦合，静置试验模型至稳定状态。
根据试验内容及测点位置，将耦合处理后的同轴电缆与相似材料一同布设。相似材料及电缆布设完毕后，将模型静置一周后，开始试验。
S4.对相似材料模型试样进行模拟加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值。
试验正式开始后，加载同时启动矢量网络分析仪监测，并进行VNA频域模式下进行波形保存，保存时间间隔20s；实验结束后，停止加载，停止数据保存，导出试验数据。
S5.通过频移及反射点初始间距，计算确定应变值及位移值，推算相似材料物理模型的应变及位移场分布。
上述试验方法中，电缆应变传感器可以对岩石或类煤岩试样变形及破坏全过程的数据记录，能够有效地监测岩石自身应变及损伤；并且针对预制裂隙的试样的裂隙扩展测量等问题，电缆传感器可以跨裂隙粘贴，从而测量裂隙扩展值等相关数据；此外，电缆应变传感器可以在类岩石相似材料及煤岩体内部进行监测，具有很好的延展性，传感器不会发生断裂，同轴电缆还能够承受较大的应变，不会因为煤岩体较大位移而发生失效。该系统进行试验测量的方法还具有可弯曲、抗干扰、灵敏度高等优点，同时其可连续、实时地监测被测试样或物理模型的应变及位移。
当然，上述说明并非是对本发明的限制，本发明也并不仅限于上述举例，本技术领域的技术人员在本发明的实质范围内所做出的变化、改型、添加或替换，也应属于本发明的保护范围。

Claims (9)

  1. 一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，包括应变传感器、煤岩试样、监测装置和计算机，所述应变传感器包括同轴电缆、接头压合器和公头连接器，同轴电缆上布置有多个接头压合器，同轴电缆两端设置公头连接器；所述应变传感器根据煤岩试样和待测参数装配组合方式；所述监测装置包括矢量网络分析仪和终端负载，终端负载接入应变传感器的一端，矢量网络分析仪接入应变传感器的另一端；计算机对采集数据进行处理和记录，记录反射点对应的特征波谷的频率值，通过数据转换计算反射点之间的应变值。
  2. 根据权利要求1所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，煤岩试样包括单轴压缩煤岩试样、三点弯曲试验煤岩试样和相似材料模型试样。
  3. 根据权利要求2所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，所述单轴压缩煤岩试样呈圆柱形，应变传感器黏贴在煤岩试样上并按照设置的包角螺旋缠绕。
  4. 根据权利要求2所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，所述三点弯曲试验煤岩试样呈长方体，应变传感器黏贴在煤岩试样中部，所述应变传感器施加预紧力。
  5. 根据权利要求2所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，所述应变传感器埋设在相似材料模型试样中，应变传感器与相似材料模型试样变形相耦合。
  6. 一种基于电缆传感技术的单轴压缩试验方法，利用权利要求1至3任一项所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，步骤包括：
    S1.加工煤岩试样，制作应变传感器；
    S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
    S3.应变传感器螺旋缠绕布置在煤岩试样上，通过环氧树脂黏贴并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变；
    S4.通过试验机施加轴向载荷，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
    S5.计算煤岩试样发生轴向变形，包角为 θ时，存在关系式：
    其中， ε f是电缆上的应变， ε a是煤岩试样的轴向应变， v是煤岩试样的泊松比。
  7. 一种基于电缆传感技术的三点弯曲试验方法，利用权利要求1、2、4任一项所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，步骤包括：
    S1.加工煤岩试样，制作应变传感器；
    S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
    S3.将应变传感器固定煤岩试样上，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，调整加载装置跨距，调整岩石试件位于加载装置的中心位置；
    S4.通过试验机施加线性载荷，直至试件完全断裂停止加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
    S5.通过频移以及反射点初始间距，计算确定应变值及位移值，推算预制裂隙的岩石试件裂隙宽度扩展值。
  8. 根据权利要求7所述的一种基于电缆传感技术的三点弯曲试验方法，其特征在于，所述线性载荷的加载速率小于等于0.03mm/min，所述频移与应变呈正比。
  9. 一种基于电缆传感技术的相似材料模拟试验方法，利用权利要求1、2、5任一项所述的一种基于电缆传感技术的室内岩石力学试验变形测量系统，其特征在于，步骤包括：
    S1.制作应变传感器；
    S2.通过应变传感器的公头连接器与矢量网络分析仪、终端负载相连；
    S3.将应变传感器以相似材料的骨料包裹，并施加预紧力，应变传感器初始状态保持0.05%-0.1%的正应变，相似材料模型试样与应变传感器耦合，静置试验模型至稳定状态；
    S4.对相似材料模型试样进行模拟加载，同时利用矢量网络分析仪和计算机分析监测数据并确定同轴电缆的应变值；
    S5.过频移及反射点初始间距，计算确定应变值及位移值，推算相似材料物理模型的应变及位移场分布。
PCT/CN2023/097919 2022-07-22 2023-06-02 基于电缆传感技术的室内岩石力学试验变形测量系统及方法 WO2024016857A1 (zh)

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