A three-way stress monitoring device and method based on an eddy current sensor

Abstract

The application provides a three-way stress monitoring device and method based on an eddy current sensor, six eddy current sensors are uniformly distributed in a metal support circular pipe, the load stress of coal and rock bodies in three different directions can be measured, and thus the problem that a traditional monitoring device can only measure the load stress in the vertical direction of the coal and rock bodies is solved. The data accuracy is improved, the measurement data are enriched, and the change of the load stress of the coal and rock bodies in each direction can be better monitored; the sensor and the oil bag are integrated, and the sensor can directly measure the load stress of the coal and rock bodies at the corresponding position of the drill hole. Compared with the split structure of the traditional monitoring device, the sensor is less affected, the measurement error is smaller, and the measurement result is more accurate.

Description

Technical Field

[0001] This invention relates to the field of stress monitoring technology, and in particular to a triaxial stress monitoring device and method based on an eddy current sensor. Background Technology

[0002] Stress monitoring devices are primarily used for stress monitoring in underground coal or rock masses, such as monitoring the pre-support pressure of the coal face ahead of the working face and the support pressure of reserved coal pillars. These devices measure changes in the internal stress field of the coal or rock mass due to mining activities, and are an important means of studying the dynamic pressure action in mining areas. They can also be used for predicting and analyzing the trends of mine rockbursts. With increasing emphasis on mine pressure monitoring and control in coal mines, and the growing prominence of mine pressure issues, stress monitoring equipment has become an indispensable tool for coal mine pressure monitoring and research.

[0003] Currently, common stress monitoring equipment mainly adopts a split structure of hydraulic pressure unit and stress sensor. The hydraulic pressure unit is placed in a pre-drilled borehole, and then oil is injected into it to apply pressure, fixing it in place. The stress sensor and other supporting equipment are then installed. When the coal and rock mass is subjected to stress and undergoes fracturing deformation, the coal and rock mass compresses the hydraulic pressure unit, causing a change in oil pressure in the oil pipes. This, in turn, causes the strain gauge in the stress sensor to deform. The strain gauge converts the deformation into a voltage signal, which is then converted into a communication signal by a transmitter to communicate with the upstream equipment. The upstream equipment converts the electrical signal into a pressure signal, thus completing the measurement of the stress in the coal and rock mass.

[0004] Currently, most common stress monitoring equipment adopts a split structure of hydraulic pressure unit and stress sensor. Due to the constraints of the hydraulic pressure unit's design, it can only measure the load stress in the vertical direction of the coal or rock mass, and cannot measure loads in other directions, resulting in relatively limited information. In addition, the oil pipe is prone to bending in the borehole, affecting the oil pressure and thus impacting the measurement results. Summary of the Invention

[0005] This invention provides a triaxial stress monitoring device and method based on an eddy current sensor, aiming to solve the problems of single measurement direction and insufficient measurement accuracy of traditional stress monitoring equipment.

[0006] Therefore, the first objective of this invention is to provide a triaxial stress monitoring device based on an eddy current sensor, comprising:

[0007] A high-pressure rubber hose oil bladder and a metal round tube; wherein the high-pressure rubber hose oil bladder is fitted onto the outer wall of the metal round tube;

[0008] Metal connectors are provided at both ends of the high-pressure hose oil bladder; a metal plug is provided at one end of the inner wall of the metal round tube in conjunction with the metal connector;

[0009] An oil injection pump is installed and connected to the high-pressure hose oil bladder via an oil injection pipe to inject oil into the high-pressure hose oil bladder; several eddy current sensors are installed, with the probes of the eddy current sensors penetrating from the inner wall of the metal oil pipe into the high-pressure hose oil bladder, and the eddy current sensor probes are connected to a display via a communication cable.

[0010] The high-pressure hose oil bladder is equipped with several metal plates, each of which is positioned opposite an eddy current sensor probe.

[0011] Inside the high-pressure hose oil bladder, there are six metal plates attached, corresponding to six eddy current sensor probes evenly distributed on the metal tube, which are connected to the display via six communication cables.

[0012] The oil injection pipe is controlled by a valve to control the on / off state of the oil injection pump and realize the oil injection function.

[0013] The second objective of this invention is to propose a triaxial stress monitoring method based on an eddy current sensor, comprising:

[0014] The three-dimensional stress monitoring device, consisting of a high-pressure rubber hose bladder, a metal round tube, a metal joint, and a metal plug, is pushed to a designated position inside the borehole.

[0015] After being pushed into place, oil is injected into the high-pressure hose oil bladder using an oil injection pump. When the oil pressure in the high-pressure hose oil bladder reaches the set value, the oil injection is stopped to ensure that the high-pressure hose oil bladder fits tightly against the borehole wall.

[0016] When the oil pressure of the high-pressure hose bladder reaches the set value, the distance between the eddy current sensor probe installed on the metal tube and the metal plate attached to the high-pressure hose bladder is the initial value.

[0017] When the coal and rock mass is subjected to stress and deforms, the high-pressure hose oil bladder is squeezed and deformed, causing a change in the distance between the eddy current sensor probe and the metal plate; by reading the distance data on the display, the load stress value of the coal and rock mass is calculated.

[0018] Unlike existing technologies, the triaxial stress monitoring device based on eddy current sensors provided by this invention uniformly distributes three sets of six eddy current sensors within a metal support tube. This allows for the measurement of load stress in coal and rock masses in three different directions, thus solving the problem that traditional monitoring equipment can only measure load stress in the vertical direction of the coal and rock mass. This increases data accuracy and enriches the measurement data, enabling better monitoring of load stress changes in various directions of the coal and rock mass. The integrated sensor and oil bladder design allows the sensor to directly measure the load stress in the coal and rock mass at the corresponding borehole location. Compared to the split structure of traditional monitoring equipment, the sensor is less affected by external factors, has smaller measurement errors, and provides more accurate measurement results. Attached Figure Description

[0019] The present invention and / or its additional aspects and advantages will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 This is a schematic diagram of the structure of a triaxial stress monitoring device based on an eddy current sensor provided by the present invention.

[0021] Figure 2 This is a schematic diagram of the arrangement of eddy current sensors in a triaxial stress monitoring device based on eddy current sensors provided by the present invention.

[0022] Figure 3 This is a schematic flowchart of a triaxial stress monitoring method based on an eddy current sensor provided by the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] Figure 1 A triaxial stress monitoring device based on an eddy current sensor, provided in an embodiment of the present invention, includes:

[0025] A high-pressure rubber hose oil bladder 1 and a metal round tube 2; wherein, the high-pressure rubber hose oil bladder 1 is sleeved on the outer wall of the metal round tube 2;

[0026] Metal connectors are provided at both ends of the high-pressure hose oil bladder 1; a metal plug 5 is provided at one end of the inner wall of the metal tube 2 to fit the metal connector; in this invention, two metal connectors are provided, namely a first metal connector 3 and a second metal connector 4, wherein the second metal connector 4 and the metal plug 5 are provided at one end of the metal tube 2 for cooperation.

[0027] An oil pump 8 is installed and connected to the high-pressure hose oil bladder 1 via an oil injection pipe 6 to inject oil into the high-pressure hose oil bladder 1; several eddy current sensors are installed, and the probes 10 of the eddy current sensors penetrate into the high-pressure hose oil bladder 1 from the inner wall of the metal oil pipe 2. The eddy current sensor probes 10 are connected to the display 12 via a communication cable 11.

[0028] The high-pressure hose oil bladder is provided with several metal plates 9, each metal plate 9 being positioned directly opposite an eddy current sensor probe 10.

[0029] like Figure 2As shown, inside the high-pressure hose oil bladder 1, there are six metal plates 9 attached, corresponding to six eddy current sensor probes 10 evenly distributed on the metal round tube 2, which are connected to the display 12 through six communication cables 11.

[0030] The oil injection pipe 6 is controlled by a valve 7 to control the on / off state of the oil injection pump 8, thereby realizing the oil injection function.

[0031] In actual use, the components—high-pressure hose oil bladder 1, metal round tube 2, first metal connector 3, second metal connector 4, and metal plug 5—are pushed to the designated position inside the borehole. After being pushed into place, oil is injected into the high-pressure hose oil bladder 1 using the oil injection pump 8. Oil injection stops when the oil pressure in the high-pressure hose oil bladder 1 reaches the set value, at which point the high-pressure hose oil bladder 1 is in close contact with the borehole wall. The display 12 is then turned on, and the load stress on the coal and rock mass is calculated by reading the values.

[0032] When the oil pressure in the high-pressure hose bladder 1 reaches the set value, the initial distance between the eddy current sensor probe 10 mounted on the metal tube 2 and the metal plate 9 attached to the high-pressure hose bladder 1 is set. After the monitoring device is activated, the eddy current sensor probe 10 generates an alternating magnetic field, causing eddy currents to be generated in the metal plate 9. The eddy currents generated by the metal plate 9, in turn, affect the impedance of the eddy current sensor probe 10, thereby allowing the distance between the eddy current sensor probe 10 and the metal plate 9 to be measured.

[0033] When the coal and rock mass is subjected to stress and deforms, the high-pressure hose oil bladder 1 is compressed and deformed, causing a change in the distance between the eddy current sensor probe 10 and the metal plate 9. By reading the distance data on the display 12 and then calculating, the load stress value of the coal and rock mass can be obtained.

[0034] like Figure 3 Furthermore, the present invention also provides a triaxial stress monitoring method based on an eddy current sensor, comprising:

[0035] The three-dimensional stress monitoring device, consisting of a high-pressure rubber hose bladder, a metal round tube, a metal joint, and a metal plug, is pushed to a designated position inside the borehole.

[0036] After being pushed into place, oil is injected into the high-pressure hose oil bladder using an oil injection pump. When the oil pressure in the high-pressure hose oil bladder reaches the set value, the oil injection is stopped to ensure that the high-pressure hose oil bladder fits tightly against the borehole wall.

[0037] When the oil pressure of the high-pressure hose bladder reaches the set value, the distance between the eddy current sensor probe installed on the metal tube and the metal plate attached to the high-pressure hose bladder is the initial value.

[0038] When the coal and rock mass is subjected to stress and deforms, the high-pressure hose oil bladder is squeezed and deformed, causing a change in the distance between the eddy current sensor probe and the metal plate; by reading the distance data on the display, the load stress value of the coal and rock mass is calculated.

[0039] Drill a borehole at the test site designed for the mine roadway. Insert the triaxial stress monitoring device into the bottom of the borehole, connect the communication cable and monitor, and connect the oil injection pipe to the oil injection pump. Open the valve to allow the oil injection pump to inject hydraulic oil or other mining oil into the high-pressure hose bladder. When the pressure gauge on the oil injection pump reaches the set value, stop the oil injection, close the valve, and remove the oil injection pump. Turn on the monitor; the displayed value is the initial value. As the borehole wall deforms, the monitor records the displacement value in real time until monitoring ends. After monitoring, first turn off the monitor and disconnect the communication cable; then open the valve to drain the oil from the high-pressure hose bladder, and then extract the triaxial stress monitoring device from the borehole. The monitor can be taken to the surface and connected to a computer to calculate and analyze the changes in triaxial stress with the movement of the surrounding rock in the roadway.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0043] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0044] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the described embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any of the following techniques known in the art, or a combination thereof: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0045] Those skilled in the art will understand that all or part of the steps of the method described in the embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0046] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0047] The storage medium mentioned may be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the embodiments within the scope of the present invention.

Claims

1. A triaxial stress monitoring device based on an eddy current sensor, characterized in that, include: A high-pressure rubber hose oil bladder and a metal round tube; wherein the high-pressure rubber hose oil bladder is fitted onto the outer wall of the metal round tube; Metal connectors are provided at both ends of the high-pressure hose oil bladder; a metal plug is provided at one end of the inner wall of the metal round tube in conjunction with the metal connector; An oil injection pump is installed and connected to the high-pressure hose oil bladder via an oil injection pipe to inject oil into the high-pressure hose oil bladder; several eddy current sensors are installed, with the probes of the eddy current sensors penetrating from the inner wall of the metal oil pipe into the high-pressure hose oil bladder, and the eddy current sensor probes are connected to a display via a communication cable. The high-pressure hose oil bladder is equipped with several metal plates, each of which is positioned opposite an eddy current sensor probe.

2. The triaxial stress monitoring device based on an eddy current sensor according to claim 1, characterized in that, Inside the high-pressure hose oil bladder, there are six metal plates attached, corresponding to six eddy current sensor probes evenly distributed on the metal tube, which are connected to the display via six communication cables.

3. The triaxial stress monitoring device based on an eddy current sensor according to claim 1, characterized in that, The oil injection pipe is controlled by a valve to control the on / off state of the oil injection pump and realize the oil injection function.

4. A triaxial stress monitoring method based on an eddy current sensor, characterized in that, include: The three-dimensional stress monitoring device, consisting of a high-pressure rubber hose bladder, a metal round tube, a metal joint, and a metal plug, is pushed to a designated position inside the borehole. After being pushed into place, oil is injected into the high-pressure hose oil bladder using an oil injection pump. When the oil pressure in the high-pressure hose oil bladder reaches the set value, the oil injection is stopped to ensure that the high-pressure hose oil bladder fits tightly against the borehole wall. When the oil pressure of the high-pressure hose bladder reaches the set value, the distance between the eddy current sensor probe installed on the metal tube and the metal plate attached to the high-pressure hose bladder is the initial value. When the coal and rock mass is subjected to stress and deforms, the high-pressure hose oil bladder is squeezed and deformed, causing a change in the distance between the eddy current sensor probe and the metal plate; by reading the distance data on the display, the load stress value of the coal and rock mass is calculated.

5. The triaxial stress monitoring method based on an eddy current sensor according to claim 4, characterized in that, When the oil pressure in the high-pressure hose bladder reaches the set value, the distance between the eddy current sensor probe installed on the metal tube and the metal plate attached to the high-pressure hose bladder is the initial value. After the monitoring device is started, the eddy current sensor probe generates an alternating magnetic field, which causes the metal plate to generate eddy currents. The eddy currents generated by the metal plate affect the impedance of the eddy current sensor probe, and the distance between the eddy current sensor probe and the metal plate is measured.

6. The triaxial stress monitoring method based on an eddy current sensor according to claim 4, characterized in that, After monitoring is completed, turn off the monitor and disconnect the communication cable; open the valve to drain the oil from the high-pressure hose oil bladder and extract the triaxial stress monitoring device from the borehole; the monitor can be taken to the ground and connected to a computer, and the software can be used to calculate and analyze the variation of triaxial stress with the activity of the surrounding rock in the roadway.

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