Coal rock mass stress monitoring device and system

Abstract

The invention discloses a coal-rock mass stress monitoring device and system. The coal-rock mass stress monitoring device comprises a multidirectional stress sensing hydraulic cylinder and a pressure transmitter, the multidirectional stress induction hydraulic cylinder comprises a cylindrical cylinder body, a hydraulic chamber is axially arranged in the cylindrical cylinder body, an oil injection port communicated with the hydraulic chamber is formed in the tail end of the cylindrical cylinder body, a plurality of hydraulic hole sets are evenly formed in the cylindrical cylinder body in the circumferential direction, each hydraulic hole set comprises a plurality of hydraulic holes, and the hydraulic holes are communicated with the hydraulic chamber. A hydraulic plunger is arranged in each hydraulic hole, a plurality of arc-shaped pressing plates in one-to-one correspondence with the hydraulic hole sets are arranged on the outer side of the barrel-shaped cylinder body in the circumferential direction, the hydraulic plungers in the hydraulic hole sets are connected with the corresponding arc-shaped pressing plates, and displacement sensors are arranged between the arc-shaped pressing plates and the barrel-shaped cylinder body. The input end of the pressure transmitter is connected with the oil injection port through a hydraulic oil pipe. The device can adapt to monitoring of pressure in different directions, the monitoring effect is improved, the device can be fully coupled with a drill hole wall, the monitoring precision is improved, and the stability and accuracy of long-term monitoring are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of coal rock mass stress monitoring, and in particular to a coal rock mass stress monitoring device and system. Background Art

[0002] With the increase in the depth of coal resource mining and the increase in mining intensity, coal rock dynamic disasters such as rock burst, coal and gas outbursts, and large-scale roof collapse occur frequently, seriously restricting the safe and efficient production of coal mines. Coal rock stress is the basic data for underground engineering design and construction such as tunnel design and maintenance, working face layout design, and is also the fundamental force that causes deformation and damage in geotechnical engineering such as mining. Therefore, stress monitoring of coal rock mass is crucial in preventing coal rock dynamic disasters, assessing the danger of working face areas, roof control, and tunnel support.

[0003] At present, the most commonly used equipment for coal rock stress monitoring is a liquid-filled expansion pillow-type borehole stress gauge improved from the Glotzi pressure box. It consists of upper and lower clamps and a pressure pillow, and is fixedly installed by drilling penetration. When the stress around the borehole changes, the liquid pressure in the pressure pillow changes, and the pressure transmitter converts the liquid pressure into an electrical signal or frequency signal to achieve stress monitoring. However, this monitoring method has certain limitations in practical applications, mainly manifested in: ① Liquid-filled expansion pillow borehole stress gauges can usually only perform unidirectional monitoring. When the principal stress direction is unclear or there are multi-directional stress changes in the mine pressure environment, the installation of the stress gauge is blind and the monitoring effect is limited; ② The outer diameter of the strain gauge is smaller than the diameter of the drilled hole. Due to the limited expansion deformation of the oil pressure pillow, the strain gauge cannot fully fit the drilled hole wall, the coupling effect is poor, and the monitoring accuracy is affected.

[0004] ③ The pressure pillow is prone to deformation after being pressurized for a long time, which leads to pressure relief and requires pressure replenishment, affecting the stability and accuracy of long-term monitoring. Summary of the invention

[0005] The purpose of the present invention is to provide a coal rock stress monitoring device and system to solve the problems existing in the above-mentioned prior art, which can adapt to the monitoring of pressure from different directions, improve the monitoring effect, fully couple with the borehole wall, improve the monitoring accuracy, and ensure the stability and accuracy of long-term monitoring.

[0006] To achieve the above object, the present invention provides the following solutions: The present invention provides a coal rock mass stress monitoring device, comprising a multi-directional stress sensing hydraulic cylinder and a pressure transmitter; The multi-directional stress-sensing hydraulic cylinder comprises a cylindrical cylinder body, a hydraulic chamber is axially arranged inside the cylindrical cylinder body, an oil filling port connected to the hydraulic chamber is arranged at the tail end of the cylindrical cylinder body, a plurality of hydraulic hole groups are evenly arranged along the circumferential direction on the cylindrical cylinder body, each of the hydraulic hole groups comprises a plurality of hydraulic holes spaced apart along the axial direction, each of the hydraulic holes is arranged along the radial direction and connected to the hydraulic chamber, a hydraulic plunger is slidingly sealed in each of the hydraulic holes, a plurality of arc-shaped pressure plates corresponding to each of the hydraulic hole groups are circumferentially arranged on the outer side of the cylindrical cylinder body, the hydraulic plungers in each of the hydraulic hole groups are connected to the corresponding arc-shaped pressure plates, and a displacement sensor is arranged between each of the arc-shaped pressure plates and the cylindrical cylinder body for detecting the real-time displacement of the hydraulic plunger; The input end of the pressure transmitter is connected to the oil filling port through a hydraulic oil pipe.

[0007] In one embodiment, the multi-directional stress-sensing hydraulic cylinder is externally wrapped with an elastic protective sleeve.

[0008] In one embodiment, the arc-shaped pressure plate is fixedly connected to the hydraulic plunger via a fastening screw.

[0009] In one embodiment, the pressure transmitter includes a support seat, a pressure sensing mechanism, a first fiber grating, a second fiber grating, a fiber coupler and a pigtail. A hydraulic oil circuit is provided in the support seat, one end of the hydraulic oil circuit is connected to the oil filling port through a hydraulic oil pipe, and the pressure sensing mechanism includes a pressure-bearing diaphragm, a force transmission rod, a sensitivity-enhancing lever structure and a cantilever beam. The pressure-bearing diaphragm is arranged at the other end of the hydraulic oil circuit and fixed on the support seat, one end of the force transmission rod is fixed to the middle of the pressure-bearing diaphragm, and the other end is connected to the first free end of the sensitivity-enhancing lever structure. The second free end of the lever structure is against the upper surface of the free end of the cantilever beam, the force arm corresponding to the force applied by the force transmission rod to the sensitivity-enhancing lever structure is the first force arm, the force arm corresponding to the force applied by the cantilever beam to the sensitivity-enhancing lever structure is the second force arm, the length of the first force arm is greater than the length of the second force arm, the first fiber grating and the second fiber grating are respectively fitted on the upper surface and the lower surface at the same position of the cantilever beam, and the transmission optical fibers connected to the first fiber grating and the second fiber grating are coupled to the pigtail through the optical fiber coupler.

[0010] In one embodiment, the sensitivity enhancement lever structure includes a first link and a second link fixedly connected in an L-shape, the rotation fulcrum of the sensitivity enhancement lever structure is arranged at the junction of the first link and the second link, the length of the first link is greater than the length of the second link, the force transmission rod is connected to the free end of the first link, and the free end of the second link is abutted against the upper surface of the free end of the cantilever beam.

[0011] In one embodiment, one end of the support seat is connected to the hydraulic oil pipe through a hydraulic quick connector.

[0012] In one embodiment, the outer sealing sleeve of the support seat is provided with an outer shell, the pressure sensing mechanism, the first fiber grating, the second fiber grating and the fiber coupler are all arranged in the outer shell, and the pigtail extends from the rear end of the outer shell through the pigtail protective cover.

[0013] In one embodiment, the support seat and the housing are sealed by an O-ring.

[0014] The present invention also provides a coal rock stress monitoring system, comprising the coal rock stress monitoring device described above, and also comprising a tee, a displacement data collector and an oil pump; the tee is arranged on the hydraulic oil pipe, the two ports of the tee are connected to the hydraulic oil pipe through a first valve and a second valve respectively, the other port is connected to the oil pump through a third valve, and the displacement data collector is connected to the displacement sensor signal.

[0015] The present invention also provides a coal rock stress monitoring system, comprising the coal rock stress monitoring device described above, and also comprising a tee, a displacement data collector, an oil pump and a fiber optic Bragg grating demodulator; the tee is arranged on the hydraulic oil pipe, the two ports of the tee are connected to the hydraulic oil pipe through a first valve and a second valve respectively, and the other port is connected to the oil pump through a third valve, the displacement data collector is connected to the displacement sensor signal; the fiber optic Bragg grating demodulator is connected to the pigtail.

[0016] Compared with the prior art, the present invention has achieved the following technical effects: The coal rock stress monitoring device and system provided by the present invention, the multi-directional stress sensing hydraulic cylinder pushes the hydraulic plunger through the hydraulic oil, so that the arc pressure plate is in close contact with the borehole wall, can be fully coupled with the borehole wall, improve the monitoring accuracy, and can effectively transmit the stress of the borehole in all directions, adapt to the monitoring of pressure from different directions, and improve the monitoring effect; a displacement sensor is arranged between the arc pressure plate and the cylindrical cylinder body, which can monitor the displacement data of the hydraulic plunger in real time, and judge the direction of pressure according to the displacement change amplitude and trend in each direction; the present invention has high deformation resistance after pressurization, strong pressure maintaining ability, no pressure release phenomenon, and can ensure the stability and accuracy of long-term monitoring.

[0017] Furthermore, the pressure transmitter utilizes a sensitive lever structure and a cantilever beam to amplify tiny stress changes. The wavelength drift of the fiber grating corresponds to the pressure change, and the stress change is measured by a fiber grating demodulator. At the same time, it has good temperature self-compensation capability, anti-electromagnetic interference capability and high sensitivity, meets the requirements of intrinsic safety and explosion-proof, and can work stably in complex mining environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a partial cross-sectional structural schematic diagram of a multi-directional stress sensing hydraulic cylinder in an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a multi-directional stress sensing hydraulic cylinder in an embodiment of the present invention; Figure 3 Schematic diagram of the structure of the pressure transmitter in an embodiment of the present invention; Figure 4 is a schematic structural diagram of a pressure sensing mechanism in an embodiment of the present invention; Figure 5 It is a schematic diagram of a multi-directional stress sensing hydraulic cylinder in a drilling hole before pressurization in an embodiment of the present invention; Figure 6 It is a schematic diagram of a multi-directional stress sensing hydraulic cylinder in a borehole after pressurization in an embodiment of the present invention; Figure 7 It is a static simulation cloud diagram of a pressurized diaphragm in an embodiment of the present invention; Figure 8 It is a modal simulation cloud diagram of a pressurized diaphragm in an embodiment of the present invention; Fig. 9 Schematic diagram of a coal rock mass stress monitoring system in an embodiment of the present invention.

[0020] In the figure: 1-multi-directional stress sensing hydraulic cylinder, 101-cylindrical cylinder body, 102-hydraulic chamber, 103-oil filling port, 104-hydraulic hole, 106-sealing sleeve, 107-hydraulic plunger, 108-fastening screw, 109-arc pressure plate, 110-displacement sensor; 2-tee pipe, 201-first valve, 202-second valve, 203-third valve; 3-pressure transmitter, 301-pressure diaphragm; 302-force transmission rod; 303-sensitization lever structure; 3031-first connecting rod; 3032-second connecting rod; 304-rotating shaft; 305-cantilever beam; 306-first fiber grating; 307-second fiber grating; 308-transmission fiber; 309-fiber coupler; 310-pigtail protective sleeve; 311-pigtail; 312 -O-ring, 313-hydraulic quick connector; 314-housing; 315-support seat; 316-hydraulic oil circuit; 4-displacement data collector; 5-oil pump; 6-fiber grating demodulator; 701-borehole wall, 702-gap. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The purpose of the present invention is to provide a coal rock stress monitoring device and system to solve the problems existing in the prior art, which can adapt to the monitoring of pressure from different directions, improve the monitoring effect, fully couple with the borehole wall, improve the monitoring accuracy, and ensure the stability and accuracy of long-term monitoring.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Embodiment 1 like Figure 1-Figure 6 As shown, this embodiment provides a coal rock stress monitoring device, including a multi-directional stress sensing hydraulic cylinder 1 and a pressure transmitter 3; The multi-directional stress-sensing hydraulic cylinder 1 comprises a cylindrical cylinder body 101, wherein a hydraulic chamber 102 is axially arranged inside the cylindrical cylinder body 101 for containing hydraulic oil, and an oil filling port 103 connected to the hydraulic chamber 102 is arranged at the tail end of the cylindrical cylinder body 101, and hydraulic oil can be filled into the hydraulic chamber 102 from the oil filling port 103, and a plurality of hydraulic hole groups are evenly arranged along the circumference of the cylindrical cylinder body 101, and each hydraulic hole group comprises a plurality of hydraulic holes 104 spaced apart along the axial direction. In this embodiment, six hydraulic hole groups are arranged, and each hydraulic hole group comprises four hydraulic holes 104, and each hydraulic hole 104 is arranged along the radial direction and connected to the hydraulic chamber 102, and each hydraulic hole 104 is provided with a hydraulic plunger 107 in a sliding seal, and a sealing sleeve 106 is provided at the end of the hydraulic plunger 107, and the hydraulic plunger 107 can reciprocate in the hydraulic hole 104 and pass through the sealing sleeve 1 06 forms a sliding sealing structure with the hydraulic hole 104. The movement of the hydraulic piston 107 is driven by the oil pressure of the hydraulic chamber 102. The movement of each group of hydraulic pistons 107 does not affect each other. Each group of hydraulic pistons shares a hydraulic chamber 102. Six arc-shaped pressure plates 109 corresponding to each hydraulic hole group are arranged along the circumferential direction on the outer side of the cylindrical cylinder body 101. The hydraulic pistons 107 in each hydraulic hole group are connected with the corresponding arc-shaped pressure plates 109. The arc-shaped pressure plates 109 are evenly distributed along the circumferential direction of the cylindrical cylinder body 101. When the internal pressure of the hydraulic chamber 102 increases, the hydraulic piston 107 is pushed. The hydraulic piston 107 pushes the arc-shaped pressure plates 109 to move radially outward. Displacement sensors 110 are arranged between each arc-shaped pressure plate 109 and the cylindrical cylinder body 101 to detect the real-time displacement of the hydraulic piston 107 and provide real-time displacement data of the hydraulic piston 107. The input end of the pressure transmitter 3 is connected to the oil filling port 103 through a hydraulic oil pipe.

[0025] In this embodiment, in order to prevent rock particles, dust and other impurities from entering the hydraulic plunger assembly during installation and use, the multi-directional stress sensing hydraulic cylinder 1 is wrapped with an elastic protective sleeve, and the elastic protective sleeve can be a rubber sleeve.

[0026] In this embodiment, the arc-shaped pressure plate 109 is fixedly connected to the hydraulic plunger 107 via a fastening screw 108 .

[0027] In this embodiment, the pressure transmitter 3 includes a support seat 315, a pressure sensing mechanism, a first fiber grating 306, a second fiber grating 307, a fiber coupler 309 and a pigtail 311. A hydraulic oil circuit 316 is provided in the support seat 315. One end of the hydraulic oil circuit 316 is connected to the oil filling port 103 through a hydraulic oil pipe. The pressure sensing mechanism includes a pressure-bearing diaphragm 301, a force transmission rod 302, a sensitivity-enhancing lever structure 303 and a cantilever beam 305. The pressure-bearing diaphragm 301 is arranged at the other end of the hydraulic oil circuit 316 and fixed on the support seat 315. The pressure-bearing diaphragm 301 is fixed on the support seat 315 by a peripheral fixed support. One end of the force transmission rod 302 is fixed to the middle of the pressure-bearing diaphragm 301, and the other end is connected to the first free end of the sensitivity-enhancing lever structure 303. The second free end of the sensitivity enhancement lever structure 303 is against the upper surface of the free end of the cantilever beam 305, the force arm corresponding to the force applied by the force transmission rod 302 to the sensitivity enhancement lever structure 303 is the first force arm, the force arm corresponding to the force applied by the cantilever beam 305 to the sensitivity enhancement lever structure 303 is the second force arm, the length of the first force arm is greater than the length of the second force arm, the first fiber grating 306 and the second fiber grating 307 are respectively fitted on the upper surface and the lower surface of the cantilever beam 305 at the same position, when the cantilever beam 305 is bent and deformed, the central wavelengths of the first fiber grating 306 and the second fiber grating 307 drift, and the transmission optical fiber 308 connected to the first fiber grating 306 and the second fiber grating 307 are coupled to the pigtail 311 through the optical fiber coupler 309.

[0028] In this embodiment, the sensitivity enhancement lever structure 303 includes a first connecting rod 3031 and a second connecting rod 3032 fixedly connected in an L shape, and the rotation fulcrum of the sensitivity enhancement lever structure 303 is set at the junction of the first connecting rod 3031 and the second connecting rod 3032. The sensitivity enhancement lever structure 303 can rotate freely around the rotating shaft 304 at its rotation fulcrum. The length of the first connecting rod 3031 is greater than the length of the second connecting rod 3032. The force transmission rod 302 is connected to the free end of the first connecting rod 3031, and the free end of the second connecting rod 3032 is against the upper surface of the free end of the cantilever beam 305.

[0029] In this embodiment, one end of the support seat 315 is connected to the hydraulic oil pipe through the hydraulic quick connector 313, which is convenient and quick to install.

[0030] In this embodiment, the outer sealing sleeve of the support seat 315 is provided with a shell 314, the pressure sensing mechanism, the first fiber grating 306, the second fiber grating 307 and the fiber coupler 309 are all arranged in the shell 314, and the pigtail 311 extends from the rear end of the shell 314 through the pigtail protective cover 310.

[0031] In this embodiment, the support seat 315 and the housing 314 are sealed by an O-ring 312 .

[0032] The first fiber grating 306 and the second fiber grating 307 are located on the upper and lower surfaces of the cantilever beam 305 at the same position and in the same temperature field. The deformations on the upper and lower surfaces of the cantilever beam 305 are equal in magnitude and opposite in direction, which can eliminate the temperature influence during measurement and realize temperature self-compensation.

[0033] The temperature self-compensation principle is as follows: When the strain and temperature act simultaneously on the first fiber grating 306 attached to the cantilever beam 305, the drift of its reflection wavelength can be expressed as: , When the strain and temperature act simultaneously on the second fiber grating 307 pasted under the cantilever beam 305, the drift of its reflection wavelength can be expressed as: , Where: is the initial center wavelength of the first fiber grating 306; is the reflection wavelength drift of the first fiber grating 306; is the initial center wavelength of the second fiber grating 307; is the reflection wavelength drift of the second fiber grating 307; is the effective elastic-optical coefficient of the optical fiber; is the axial strain on the first fiber Bragg grating 306; is the axial strain on the second fiber grating 307; is the thermal expansion coefficient of the optical fiber; is the thermo-optical coefficient of the optical fiber; is the temperature change of the first fiber grating 306; is the temperature change of the second fiber grating 307.

[0034] When the cantilever beam 305 is bent by force, the strains of the fiber gratings on the upper and lower surfaces are equal in magnitude and opposite in direction, that is, ; and the two fiber gratings are in the same temperature field, that is, , can be obtained , Right now , Eliminate temperature effects during measurement.

[0035] like Figure 7 As shown, a static simulation analysis is performed on the compressed diaphragm 301. As the compressed load increases, the displacement of the diaphragm shows an increasing trend. The displacement at the center of the diaphragm is the largest and gradually decreases along the radial direction. Therefore, the force transmission rod 302 should be fixed at the center of the diaphragm to ensure uniform force and maximize the load transmission effect.

[0036] like Figure 8 As shown, the modal simulation analysis of the pressure diaphragm 301 shows that the center of the diaphragm has the maximum deformation at the first-order natural frequency. The pressure diaphragm 301 has good dynamic characteristics and is suitable for measuring high-frequency pressure changes. The natural frequency is high and will not resonate with the coal rock mass to cause signal distortion.

[0037] The pressure-bearing diaphragm 301 is subjected to pressure, and the force is transmitted to the first connecting rod 3031 of the sensitivity-enhancing lever structure 303 through the force transmission rod 302. According to the moment conservation formula, the force is amplified and transmitted to the end of the cantilever beam 305 through the second connecting rod 3032 of the sensitivity-enhancing lever structure 303. The force transmitted from the pressure-bearing diaphragm 301 to the cantilever beam 305 is effectively amplified, thereby improving the ability to perceive slight pressure changes.

[0038] The relevant formula is as follows: The pressure on the pressure diaphragm 301 Acting on its effective area , the force generated for: , The force is transmitted to the first connecting rod 3031 of the sensitivity enhancement lever structure 303 through the force transmission rod 302, so that the sensitivity enhancement lever structure 303 rotates around the axis, driving the second connecting rod 3032 to apply force to the top of the cantilever beam 305. , causing the cantilever beam to bend.

[0039] From the moment balance we can get , In the formula, is the length of the first lever arm, is the length of the second lever arm.

[0040] , The force is amplified times.

[0041] The force analysis of the cantilever beam 305 and the calculation process of the fiber grating wavelength drift are as follows: Here, the cantilever beam 305 is taken as an isosceles triangle as an example for explanation, and its bottom side is the fixed end; When force When the free end of the cantilever beam 305 is acted on, the strain at the position x on the surface of the cantilever beam 305 is for: , In the formula, is the cantilever beam length, is the distance from the x position to the fixed end, is the elastic modulus of the cantilever beam, Ax is the cross-sectional area of ​​the cantilever beam at position x, is the cantilever beam thickness.

[0042] Cantilever beam cross-sectional area at x position A x It can be expressed as: , In the formula, is the cantilever beam width at position x, is the width of the cantilever beam at the fixed end.

[0043] It can be concluded that: , When the cantilever beam 305 is bent, the fiber grating attached to the cantilever beam 305 undergoes cooperative deformation, and the deformation of the fiber grating is approximately the deformation of the cantilever beam. At this time: , Combined with the above fiber Bragg grating formula, the relationship between the pressure on the pressure-bearing membrane 301 and the fiber Bragg grating wavelength drift can be obtained as follows: .

[0044] Embodiment 2 like Fig. 9 As shown, this embodiment provides a coal rock stress monitoring system, including the coal rock stress monitoring device described in Example 1, and also includes a tee 2, a displacement data collector 4, an oil pump 5 and a fiber optic Bragg grating demodulator 6; the tee 2 is arranged on the hydraulic oil pipe, the two ports of the tee 2 are connected to the hydraulic oil pipe through the first valve 201 and the second valve 202 respectively, and the other port is connected to the oil pump 5 through the third valve 203, the displacement data collector 4 is connected to the displacement sensor 110 signal; the fiber optic Bragg grating demodulator 6 is connected to the pigtail 311.

[0045] When in use, the multi-directional stress sensing hydraulic cylinder 1 is horizontally installed in the borehole using a mounting rod equipped with an inclination sensor. Figure 5 As shown, there is a gap 702 between the multi-directional stress sensing hydraulic cylinder 1 and the borehole wall 701, and it cannot be fully coupled with the borehole wall 701. Next, the first valve 201, the second valve 202 and the third valve 203 are opened, and the oil injection pump 5 is started to inject hydraulic oil into the hydraulic chamber 102 of the multi-directional stress sensing hydraulic cylinder 1. The hydraulic plunger 107 on the multi-directional stress sensing hydraulic cylinder 1 is pushed by the action of high-pressure oil. The hydraulic plunger 107 pushes the arc-shaped pressure plate 109 to move radially outward until it is in close contact with the borehole wall 701, as shown in FIG. Figure 6As shown, the arc-shaped pressure plate 109 in six directions is effectively coupled with the borehole wall 701, and the omnidirectional stress of the borehole is better transmitted. With the continuous injection of hydraulic oil, the oil pressure gradually increases. When the oil pressure reaches the set value, the oil injection pump 5 is turned off, and the third valve 203 is closed to ensure that the pressure remains in a stable state.

[0046] The high-pressure hydraulic oil applies uniform pressure to the pressure-bearing diaphragm 301 of the pressure transmitter 3, which is transmitted to the cantilever beam 305 with fiber gratings attached to the upper and lower surfaces through the force transmission rod 302 and the sensitivity-enhancing lever structure 303, causing the cantilever beam 305 to bend and deform, and the central wavelength of the fiber grating to drift. The wavelength drift is then detected by the fiber grating demodulator 6 to establish a corresponding relationship between pressure and wavelength drift.

[0047] When the stress around the borehole changes, the borehole wall 701 applies radial inward pressure to the arc pressure plate 109, which is transmitted to the hydraulic chamber 102. The hydraulic oil pressure in the hydraulic chamber 102 changes, and the liquid pressure is converted into an optical signal through the pressure transmitter.

[0048] The displacement data collector 4 monitors the feedback of each displacement sensor 110 in real time, and can judge the direction of the pressure by comparing the displacement change amplitude and trend in each direction.

[0049] The coal rock stress monitoring device and system provided by the present invention can adapt to the monitoring of pressure from different directions, can be fully coupled with the borehole wall, and the sensitivity is improved. After pressurization, it has high anti-deformation ability and strong pressure holding ability, can ensure the stability and accuracy of long-term monitoring, and has intrinsically safe explosion-proof characteristics and anti-electromagnetic interference capabilities, and has good temperature compensation capabilities.

[0050] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A coal rock mass stress monitoring device, characterized in that: Includes a multi-directional stress-sensing hydraulic cylinder and a pressure transmitter; The multi-directional stress-sensing hydraulic cylinder comprises a cylindrical cylinder body, a hydraulic chamber is axially arranged inside the cylindrical cylinder body, an oil filling port connected to the hydraulic chamber is arranged at the tail end of the cylindrical cylinder body, a plurality of hydraulic hole groups are evenly arranged along the circumferential direction on the cylindrical cylinder body, each of the hydraulic hole groups comprises a plurality of hydraulic holes spaced apart along the axial direction, each of the hydraulic holes is arranged along the radial direction and connected to the hydraulic chamber, a hydraulic plunger is slidingly sealed in each of the hydraulic holes, a plurality of arc-shaped pressure plates corresponding to each of the hydraulic hole groups are circumferentially arranged on the outer side of the cylindrical cylinder body, the hydraulic plungers in each of the hydraulic hole groups are connected to the corresponding arc-shaped pressure plates, and a displacement sensor is arranged between each of the arc-shaped pressure plates and the cylindrical cylinder body for detecting the real-time displacement of the hydraulic plunger; The input end of the pressure transmitter is connected to the oil filling port through a hydraulic oil pipe.

2. The coal rock mass stress monitoring device according to claim 1, characterized in that: The multi-directional stress sensing hydraulic cylinder is externally wrapped with an elastic protective sleeve.

3. The coal rock mass stress monitoring device according to claim 1, characterized in that: The arc-shaped pressing plate is fixedly connected to the hydraulic plunger via a fastening screw.

4. The coal rock mass stress monitoring device according to claim 1, characterized in that: The pressure transmitter includes a support seat, a pressure sensing mechanism, a first fiber grating, a second fiber grating, a fiber coupler and a pigtail. A hydraulic oil circuit is provided in the support seat. One end of the hydraulic oil circuit is connected to the oil filling port through a hydraulic oil pipe. The pressure sensing mechanism includes a pressure-bearing diaphragm, a force transmission rod, a sensitivity-enhancing lever structure and a cantilever beam. The pressure-bearing diaphragm is arranged at the other end of the hydraulic oil circuit and fixed on the support seat. One end of the force transmission rod is fixed to the middle of the pressure-bearing diaphragm, and the other end is connected to the first free end of the sensitivity-enhancing lever structure. The second free end of the cantilever beam is against the upper surface of the free end of the cantilever beam, the force arm corresponding to the force applied by the force transmission rod to the sensitivity enhancement lever structure is the first force arm, the force arm corresponding to the force applied by the cantilever beam to the sensitivity enhancement lever structure is the second force arm, the length of the first force arm is greater than the length of the second force arm, the first fiber grating and the second fiber grating are respectively fitted on the upper surface and the lower surface of the same position of the cantilever beam, and the transmission optical fibers connected to the first fiber grating and the second fiber grating are coupled to the pigtail through the optical fiber coupler.

5. The coal rock mass stress monitoring device according to claim 4, characterized in that: The sensitivity enhancement lever structure includes a first connecting rod and a second connecting rod fixedly connected in an L shape, the rotation fulcrum of the sensitivity enhancement lever structure is arranged at the junction of the first connecting rod and the second connecting rod, the length of the first connecting rod is greater than the length of the second connecting rod, the force transmission rod is connected to the free end of the first connecting rod, and the free end of the second connecting rod is abutted against the upper surface of the free end of the cantilever beam.

6. The coal rock mass stress monitoring device according to claim 4, characterized in that: One end of the support seat is connected to the hydraulic oil pipe through a hydraulic quick connector.

7. The coal rock mass stress monitoring device according to claim 4, characterized in that: The outer sealing sleeve of the support seat is provided with a shell, the pressure sensing mechanism, the first fiber grating, the second fiber grating and the fiber coupler are all arranged in the shell, and the pigtail extends from the rear end of the shell through the pigtail protective cover.

8. The coal rock mass stress monitoring device according to claim 7, characterized in that: The support seat and the housing are sealed by an O-ring.

9. A coal rock mass stress monitoring system, characterized in that: A coal rock stress monitoring device comprising any one of claims 1 to 8, further comprising a tee, a displacement data collector and an oil pump; the tee is arranged on the hydraulic oil pipe, the two ports of the tee are connected to the hydraulic oil pipe through a first valve and a second valve respectively, the other port is connected to the oil pump through a third valve, and the displacement data collector is connected to the displacement sensor signal.

10. A coal rock mass stress monitoring system, characterized in that: A coal rock stress monitoring device comprising any one of claims 4 to 8, further comprising a tee, a displacement data collector, an oil pump and a fiber optic Bragg grating demodulator; the tee is arranged on the hydraulic oil pipe, the two ports of the tee are connected to the hydraulic oil pipe through a first valve and a second valve respectively, the other port is connected to the oil pump through a third valve, the displacement data collector is connected to the displacement sensor signal; the fiber optic Bragg grating demodulator is connected to the pigtail.

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