A three-dimensional stress measuring device and system for coal and rock mass

Abstract

This utility model belongs to the field of coal and rock mass stress monitoring, specifically relating to a three-dimensional stress measuring device and system for coal and rock masses. The measuring device includes a cylindrical structural component, a pre-mining horizontal stress measuring unit, a cutting horizontal stress measuring unit, and a vertical stress measuring unit, with the three measuring units orthogonal to each other in pairs. A cross-shaped handle is welded to the axial tail end of the cylindrical structural component. A self-locking anchor claw structure passes through the central circular hole, passes through the cross-shaped handle, and is welded to the axial tail end of the cylindrical structural component. A steel oil pipe is welded to the corresponding oil line of the cylindrical structural component. This utility model, through the orthogonal measuring units and independent oil lines, collects the stress at the plumb bob, pre-mining horizontal, and cutting horizontal levels respectively, solving the problem that existing equipment can only measure a single direction or cannot measure multiple directions. The arc-shaped protective cover and multi-section plunger ensure tight coupling with the borehole wall, preventing coal dust intrusion, significantly improving data accuracy, and making it more suitable for effective monitoring in areas with complex structures.

Description

Technical Field

[0001] This utility model belongs to the field of coal and rock mass stress monitoring, specifically relating to a coal and rock mass triaxial stress measuring device and measuring system. Background Technology

[0002] Stress is the fundamental driving force causing deformation and failure of the surrounding rock in underground spaces during mining engineering. Related studies have shown that the triaxial stress changes in coal and rock masses are significantly related to their dynamic instability. To comprehensively reveal the stress distribution patterns in coal and rock masses, it is necessary to monitor their vertical and horizontal stresses. Current monitoring methods involve arranging multiple measuring units axially and radially on a cylindrical probe. During operation, these measuring units are in close contact with the borehole wall to form a pressure-bearing surface, measuring the vertical, radial, and axial horizontal stresses of the coal and rock mass. For example, patent CN103512693A invented a coal and rock mass stress orientation monitoring device, which has three piston sensing plates on the cylinder pressure sensor to realize the orientation monitoring of coal and rock mass stress; patent CN109113789B invented a multi-directional ground pressure monitoring and positioning borehole stress sensor, which has multiple plungers set in the axial and radial directions of the cylinder to realize all-round stress monitoring; patent CN202210758174.9 disclosed a lightweight three-component stress gauge, which inserts three sets of hydraulic cylinders into the same cylinder support through bolts and concave holes to realize the lightweight design of the structure and can measure stress in different directions; patent CN202310807494.3 disclosed an anti-overhead two-stage extended range three-component stress gauge, which increases the radial stroke through the anti-overhead two-stage extended range design and realizes limit pressure holding.

[0003] However, existing technologies still have certain limitations: ① Stress gauges are prone to axial slippage under axial stress and dynamic disturbances, making it impossible to accurately monitor axial stress or even causing complete failure. This also changes the stress conditions of the radial measurement unit, seriously affecting the reliability of the overall monitoring effect; ② Media such as coal powder, slag, and coal blocks are prone to intruding into the gap between the bearing surface and the structural components under the action of borehole wall stress, forming a support with a reverse force, resulting in a large deviation between the measurement results and the actual stress; ③ Radial sensing units are easily affected by lateral friction interference from the borehole wall in non-uniform confining pressure environments, leading to a decrease in their ability to identify the direction of target stress and making it difficult to meet the measurement accuracy requirements.

[0004] Based on the above problems, there is an urgent need for a measuring device and system that can achieve triaxial stress measurement, real-time monitoring, good coupling with the borehole wall, and is suitable for complex coal seam conditions. Utility Model Content

[0005] To overcome the shortcomings of existing technologies, this utility model provides a coal and rock mass triaxial stress measurement device and system, which can achieve high-precision long-term stable monitoring of triaxial stress in complex surrounding rock environments such as high stress and dynamic disturbance, and significantly improve the authenticity and reliability of monitoring data.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] One of the objectives of this utility model is to provide a three-dimensional stress measuring device for coal and rock masses, comprising:

[0008] Cylindrical structural components;

[0009] The system comprises three measurement units: a pre-mining horizontal stress measurement unit, a cutting and mining horizontal stress measurement unit, and a vertical stress measurement unit, all orthogonal to each other. The vertical stress measurement unit and the pre-mining horizontal stress measurement unit are located radially on the cylindrical structure, while the cutting and mining horizontal stress measurement unit is located at the axial top of the cylindrical structure. The vertical stress measurement unit measures the stress component in the vertical direction of the coal and rock mass, the pre-mining horizontal stress measurement unit measures the horizontal stress component in the coal and rock mass pointing towards the working face's advancing direction, and the cutting and mining horizontal stress measurement unit measures the cutting and mining horizontal stress component parallel to the coal cutter's operating direction.

[0010] A cross-shaped shank is welded to the axial tail end of the cylindrical structure.

[0011] The self-locking anchor claw structure passes through the central round hole and is welded to the axial tail end of the cylindrical structure.

[0012] Steel oil pipes are welded to the corresponding oil lines of the cylindrical structural components;

[0013] Each measuring unit includes a stress-bearing cover plate, at least one set of multi-section plungers, at least one hydraulic cylinder, and an oil circuit. The oil circuit is connected to the hydraulic cylinder. The multi-section plungers are slidably disposed inside the hydraulic cylinder. The stress-bearing cover plate is fixed to the upper end of the corresponding multi-section plunger and completely covers the range of motion of the multi-section plunger at its maximum extension stroke.

[0014] Furthermore, the sidewall of the stress-bearing cover plate is inclined.

[0015] Furthermore, the outer surface of the stress-bearing cover plate has an arc-shaped structure that matches the contour of the borehole inner wall.

[0016] Furthermore, the multi-stage plunger has a multi-stage structure, including at least a plunger locking cap, a primary plunger, and a secondary plunger; a primary plunger sealing ring and a primary plunger retaining ring are provided between the primary plunger and the inner wall of the hydraulic cylinder, and a secondary plunger sealing ring and a secondary plunger retaining ring are provided between the secondary plunger and the inner wall of the primary plunger; a plunger retaining spring is provided at the bottom of the primary plunger to prevent the secondary plunger from contacting the bottom of the hydraulic cylinder and forming an oil buffer chamber; the plunger locking cap is fixed to the thread on the top of the hydraulic cylinder by threads.

[0017] Furthermore, the number of sections of the multi-section plunger is ≥2, which can be adjusted according to the borehole diameter to meet the measurement needs of boreholes of different sizes.

[0018] Furthermore, the self-locking anchor claw structure includes a self-locking ring and an anchor claw disc;

[0019] The self-locking ring is annular, with a diameter matching the stress gauge. It is welded to the axial tail of the cylindrical structure and has a pre-reserved notch on one side for the oil pipe to pass through. A wedge-shaped self-locking buckle is provided on the inner side of the self-locking ring, which matches the bottom of the anchor claw plate.

[0020] At least three anchor claws are evenly distributed on the anchor claw disc, and a steel wire rope is connected to the anchor claw disc and extends to the outside of the borehole.

[0021] Another objective of this invention is to provide a triaxial stress measurement system for coal and rock masses, including the aforementioned triaxial stress measurement device. This measurement system enables triaxial stress monitoring and real-time monitoring in coal and rock mass stress monitoring, exhibits good coupling with the borehole wall, and is suitable for complex coal and rock masses.

[0022] The beneficial effects of this utility model are as follows:

[0023] (1) The coal and rock mass three-dimensional stress measuring device provided by this utility model, through three orthogonal measuring units and independent oil circuits, respectively collects the stress components in the plumb line direction, the stress components in the quasi-mining horizontal direction and the stress components in the cutting horizontal direction, which solves the problem that existing equipment can only measure a single direction or cannot separate directions.

[0024] (2) The coal and rock mass three-dimensional stress measuring device provided by this utility model has a stress-bearing pressure cover plate with inclined side wall that can decompose lateral force. When stress is applied in a non-target direction, it will convert part of the lateral component force into a decomposed force along the inclined plane, so that it tends to disperse or be transmitted along the structural direction, thereby reducing the direct interference of non-target direction stress on the measurement signal. The multi-section plunger adopts a double seal with sealing ring and retaining ring. The plunger locking cap and snap ring prevent leakage and rigid impact. The overall structure can resist high stress and disturbance, extend the service life of the device and reduce the frequency of failure.

[0025] (3) The coal and rock mass triaxial stress measuring device provided by this utility model has a self-locking anchor claw structure that bears the axial load that was originally resisted by the radial measuring unit through friction. The stress state of the radial measuring unit is more stable, reducing the interference of the axial load on its measurement accuracy and improving the reliability and linear response of radial stress measurement. This enables the stress gauge to be applied more stably to high stress conditions, complex environments affected by blasting vibration or mechanical disturbance, and soft or broken rock masses.

[0026] (4) The coal and rock mass three-dimensional stress measurement system provided by this utility model transmits the stress change of the coal and rock mass to the hydraulic system instantaneously through multiple plungers. The pressure transmitter quickly converts the pressure signal into an electrical signal, which is recorded in real time by the data acquisition instrument. There is no need for core removal and inversion. It can capture stress changes in time and provide real-time and effective data support for early warning of risks such as mine rock bursts. Attached Figure Description

[0027] Figure 1 A schematic diagram of the overall triaxial stress measurement system for coal and rock mass;

[0028] Figure 2 Schematic diagram of a triaxial stress measurement device for coal and rock mass;

[0029] Figure 3 This is a structural schematic diagram of a stress-bearing cover plate;

[0030] Figure 4 This is a schematic diagram of a multi-section plunger structure;

[0031] Figure 5 This is a cross-sectional schematic diagram of a multi-section plunger;

[0032] Figure 6 This is a schematic diagram of a self-locking anchor claw structure;

[0033] Figure 7 Schematic diagram of anchor claw retraction and deployment; In the diagram: 1. Three-dimensional stress measuring device for coal and rock mass; 101. Cylindrical structural component; 102. Vertical stress measuring unit; 10201. Vertical stress bearing cover plate; 10202. Vertical measuring hydraulic cylinder; 103. Horizontal stress measuring unit for pre-mining; 104. Horizontal stress measuring unit for cutting and mining; 10401. Horizontal stress bearing cover plate for cutting and mining; 10402. Horizontal stress measuring hydraulic cylinder for cutting and mining; 105. Cross handle; 106. Self-locking anchor claw structure; 10 601. Self-locking ring; 10602. Anchor claw disc; 107. Steel oil pipe; 108. Fixing screw; 109. Multi-section plunger; 10901. Plunger locking cap; 10902. Single-section plunger; 10903. Single-section plunger retaining ring; 10904. Single-section plunger sealing ring; 10905. Two-section plunger; 10906. Two-section plunger retaining ring; 10907. Two-section plunger sealing ring; 10908. Plunger snap ring; 2. Tee; 3. Oil pump; 4. Pressure transmitter; 5. Data acquisition instrument. Detailed Implementation

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0036] Example: A three-dimensional stress measuring device for coal and rock mass, with structure as shown in the example. Figure 2 As shown, it includes a cylindrical structural component 101, a vertical stress measuring unit 102, a pre-mining horizontal stress measuring unit 103, a cutting and mining horizontal stress measuring unit 104, a cross handle 105, a self-locking anchor claw structure 106, and a steel oil pipe 107.

[0037] The vertical stress measuring unit 102 and the quasi-mining horizontal stress measuring unit 103 are located at the radial position of the cylindrical structure 101, and the cutting horizontal stress measuring unit 104 is located at the axial top end of the cylindrical structure 101; the cross handle 105 is welded to the axial tail end of the cylindrical structure 101; the circular hole in the middle of the self-locking anchor claw structure 106 passes through the cross handle 105 and is welded to the axial tail end of the cylindrical structure 101; the steel oil pipe 107 is welded to the corresponding oil line of the cylindrical structure 101.

[0038] The vertical stress measurement unit 102 is used to measure the stress component in the vertical direction of the coal and rock mass, that is, it is collinear with the direction of gravitational acceleration. The stress mainly comes from the self-weight of the overlying strata. The horizontal stress measurement unit 103 is used to measure the horizontal stress component in the coal and rock mass pointing towards the working face advancement direction. The horizontal stress measurement unit 104 is used to measure the horizontal stress component in the cutting and mining direction parallel to the coal cutter's running direction. It is also the axial direction on which the three-dimensional stress measurement device for the coal and rock mass is installed.

[0039] In this embodiment, the structure of each measurement unit is as follows:

[0040] The vertical stress measuring unit 102 is located at the radial position of the rear end of the cylindrical structure 101, and specifically includes a vertical stress bearing cover plate 10201, two fixing screws 108, two sets of multi-section plungers 109, a vertical measuring hydraulic cylinder 10202 opened on the cylindrical structure 101, and an oil passage opened inside the cylindrical structure 101; wherein the two sets of multi-section plungers 109 are respectively installed in the two vertical measuring hydraulic cylinders 10202, and the fixing screws 108 pass through the holes in the bearing cover plate and are fastened to the threaded holes at the top of the last section of the multi-section plunger (such as the second section plunger 10905).

[0041] The horizontal stress measurement unit 103 is located at the radial position of the middle end of the cylindrical structure 101. Its structure is the same as that of the vertical stress measurement unit 102, and will not be described in detail here.

[0042] The cutting and mining horizontal stress measurement unit 104 is located at the axial position of the front end of the cylindrical structure 101, and includes a cutting and mining horizontal stress bearing cover plate 10401, a fixing screw 108, a set of multi-section plungers 109, a cutting and mining horizontal stress measurement hydraulic cylinder 10402 opened on the cylindrical structure 101, and an oil passage opened inside the cylindrical structure 101; the multi-section plungers 109 are installed in the cutting and mining horizontal stress measurement hydraulic cylinder 10402, and the cutting and mining horizontal stress bearing cover plate 10401 is fixed to the corresponding multi-section plungers 109 by the fixing screw 108.

[0043] Specifically, refer to Figure 3 As shown, the stress-bearing cover plate covers the extended portion of the multi-section plunger 109. Even when the multi-section plunger 109 is fully extended, it still provides a tight seal between the multi-section plunger 109 and the cylindrical structural member 101, effectively preventing particulate media such as coal powder, slag, and coal lumps from intruding into the plunger gap under high stress. This eliminates the interference of reaction forces caused by the filling of voids by media such as coal powder, slag, and coal lumps, thereby significantly improving the accuracy and reliability of stress measurement.

[0044] The outer surface of the stress-bearing cover plate adopts an arc-shaped structure that matches the shape of the borehole inner wall, reducing the local gap between the device and the borehole wall, enhancing the contact coupling performance between the stress measuring device and the borehole wall, and ensuring that the sensor can more accurately reflect the stress of the coal and rock mass.

[0045] The stress-bearing cap plate features a sloping sidewall design, which decomposes the force into a component along the plunger's axis when subjected to non-axial disturbances or lateral pressure from the surrounding rock, preventing the plunger from jamming due to lateral forces. The cap plate can also be internally reinforced with ribs to enhance its overall rigidity and compressive strength, preventing local buckling, cracking, or structural damage under drilling impact or long-term stress, thus improving durability.

[0046] In particular, the hydraulic system of the measuring unit adopts a multi-stage, multi-section plunger structure, including at least a primary plunger and a secondary plunger. Each plunger is effectively sealed with a sealing ring and a retaining ring. The number of sections of the multi-section plunger structure can be adjusted according to the borehole diameter (≥2 sections) to adapt to the stress measurement requirements of boreholes of different sizes.

[0047] Taking a two-section plunger as an example, its structure is explained as follows:

[0048] Reference Figure 4 and Figure 5 As shown, the multi-section plunger 109 includes a plunger locking cap 10901, a first-section plunger 10902, a first-section plunger retaining ring 10903, a first-section plunger sealing ring 10904, a second-section plunger 10905, a second-section plunger retaining ring 10906, a second-section plunger sealing ring 10907, and a plunger retaining ring 10908; the direction of plunger movement is along the axis of the hydraulic cylinder.

[0049] The multi-section plunger 109 consists of a single-section plunger 10902 and a second-section plunger 10905 of different diameters connected together in sequence. The movement direction of the two plungers is along the axis of the hydraulic cylinder. The plunger locking cap 10901 is threadedly fixed to the top thread of the hydraulic cylinder, preventing the multiple plungers 109 from being ejected from the hydraulic cylinder and causing sealing failure. A plunger retaining ring 10903 and a plunger sealing ring 10904 are installed side-by-side in the sealing groove of a plunger 10902. The plunger sealing ring 10904 forms an effective seal between the plunger 10902 and the hydraulic cylinder, preventing leakage of the hydraulic medium during plunger movement and ensuring stable pressure within the system. The plunger retaining ring 10903 is positioned above the plunger sealing ring 10904, axially limiting the seal and preventing axial displacement or extrusion, thus ensuring sealing. Two plunger retaining rings 10906 and 10907 are installed side-by-side in the second... The sealing groove of the first-stage plunger 10905; the second-stage plunger sealing ring 10907 forms an effective seal between the inner wall of the second-stage plunger 10905 and the first-stage plunger 10902, preventing leakage of hydraulic medium during plunger movement and ensuring stable pressure inside the system; the second-stage plunger retaining ring 10906 is set on the upper end of the second-stage plunger sealing ring 10907, forming an axial limit on the second-stage plunger 10905, preventing axial displacement or extrusion of the sealing ring, and ensuring sealing performance; a plunger retaining ring 10908 is installed at the bottom of the first-stage plunger 10902 to prevent the second-stage plunger 10905 from contacting the bottom of the hydraulic cylinder, forming an oil buffer chamber and improving the stability of the hydraulic system; the plunger locking cap 10901 is fixed to the thread on the top of the hydraulic cylinder by threads, preventing the multiple plungers 109 from being pushed out and causing sealing failure;

[0050] When the multi-section plunger 109 is working, hydraulic oil is pumped into the hydraulic cylinder through the oil circuit, first pushing the first plunger 10902 to move axially; when the first plunger 10902 moves to its limit position, the pressure continues to act on the second plunger 10905, which then pushes it to continue extending, increasing the total stroke of the plunger. The plunger locking cap 10901 serves as a stop and limit, and axial constraint, preventing the entire plunger assembly from being pushed out of the cylinder by hydraulic pressure, causing seal failure.

[0051] refer to Figure 6 As shown, the self-locking anchor claw structure 106 includes a self-locking ring 10601 and an anchor claw disc 10602;

[0052] The self-locking ring 10601 is designed as a ring structure with a diameter matching the stress gauge. It is welded to the axial tail of the cylindrical structural member 101, and a notch is reserved on one side for the oil pipe to pass through. A wedge-shaped self-locking buckle is provided inside the self-locking ring, the geometry of which matches the bottom of the anchor claw disc 10602. When a certain force is applied, the anchor claw disc 10602 can be firmly locked onto the self-locking ring 10601.

[0053] At least three anchor claws are evenly distributed on the anchor claw disc 10602, and a steel wire rope is connected to the anchor claw disc 10602, extending to the outside of the borehole; in the initial state, the anchor claws are retracted by the constraint of the self-locking ring 10601 (e.g., Figure 7 (As shown on the left side of the middle section) to ensure that the entire device can smoothly enter the borehole and reach the predetermined depth; when it reaches the designated position, the anchor claw disc 10602 is pulled past the wedge-shaped self-locking buckle set in the self-locking ring 10601. After the bottom of the anchor claw disc 10602 passes through the wedge-shaped part, the anchor claw disc 10602 cannot retract. At this time, the anchor claw also pops out and fits tightly against the borehole wall to achieve anchoring (as shown on the left side of the middle section). Figure 7 (As shown on the right side of the middle section).

[0054] Coal and rock mass triaxial stress monitoring system (refer to) Figure 1 As shown, it includes a coal and rock mass triaxial stress measuring device 1, a three-way valve 2, an oil pump 3, a pressure transmitter 4, and a data acquisition instrument 5.

[0055] Working principle: Hydraulic oil is injected into the sealed hydraulic cylinder by oil pump 3. During the initial pressurization process to the preset pressure, the multi-section plunger 109 is pushed radially under hydraulic action until it comes into close contact with the borehole wall, forming a stable initial loading state. When the stress of the coal and rock mass changes, the borehole wall applies a load to the multi-section plunger. This load acts on the fluid in the sealed hydraulic cylinder through the plunger. Due to Pascal's principle, the pressure is transmitted instantaneously and uniformly to the entire hydraulic system. This internal pressure change is monitored by pressure transmitter 4.

[0056] When the system is working, the push rod clamps the cross handle 105 to push the coal and rock mass triaxial stress measuring device 1 horizontally to the bottom of the borehole. At this time, the coal and rock mass triaxial stress measuring device 1 cannot be tightly coupled with the borehole wall. Pressurization is carried out in the order of vertical stress measuring unit 102, pre-mining horizontal stress measuring unit 103, and cutting horizontal stress measuring unit 104. The tee 2 is opened and the oil pump 3 is started. Hydraulic oil is injected into the hydraulic cylinder of the coal and rock mass triaxial stress measuring device 1 through the steel oil pipe 107 and the oil passage opened on the cylindrical structure 101. The high pressure oil pushes the multi-section plunger 109 in the hydraulic cylinder to push the stress bearing cover plate outward and contact the borehole wall. The oil pressure gradually increases. When the set value is reached, the tee 2 is locked and the oil pump 3 is removed. The pressure transmitter 4 converts the liquid pressure into an electrical signal, which is collected by the data acquisition instrument 5 to realize stress monitoring in three directions.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above 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 above embodiments within the scope of the present invention.

Claims

1. A coal rock mass three-dimensional stress measuring device, characterized in that, include: Cylindrical structural components; The three measurement units—the horizontal stress measurement unit for pre-mining, the horizontal stress measurement unit for cutting, and the vertical stress measurement unit—are orthogonal to each other in pairs. The vertical stress measurement unit and the quasi-mining horizontal stress measurement unit are respectively set at the radial position of the cylindrical structure, and the cutting and mining horizontal stress measurement unit is set at the axial top end of the cylindrical structure. The vertical stress measurement unit is used to measure the stress component in the vertical direction of the coal and rock mass, and the quasi-mining horizontal stress measurement unit is used to measure the horizontal stress component in the coal and rock mass pointing towards the working face advancement direction. The cutting and mining horizontal stress measurement unit is used to measure the cutting and mining horizontal stress components parallel to the operating direction of the coal cutter; A cross-shaped shank is welded to the axial tail end of the cylindrical structure. The self-locking anchor claw structure passes through the central round hole and is welded to the axial tail end of the cylindrical structure. Steel oil pipes are welded to the corresponding oil lines of the cylindrical structural components; Each measuring unit includes a stress-bearing cover plate, at least one set of multi-section plungers, at least one hydraulic cylinder, and an oil circuit. The oil circuit is connected to the hydraulic cylinder. The multi-section plungers are slidably disposed inside the hydraulic cylinder. The stress-bearing cover plate is fixed to the upper end of the corresponding multi-section plunger and completely covers the range of motion of the multi-section plunger at its maximum extension stroke.

2. The coal rock mass three-dimensional stress measuring device according to claim 1, characterized in that, The sidewalls of the stress-bearing cover plate are inclined.

3. The triaxial stress measuring device for coal and rock mass according to claim 1, characterized in that, The outer surface of the stress-bearing cover plate has an arc-shaped structure that matches the contour of the borehole inner wall.

4. The triaxial stress measuring device for coal and rock mass according to claim 1, characterized in that, The multi-stage plunger has a multi-stage structure, including at least a plunger locking cap, a primary plunger, and a secondary plunger; a primary plunger sealing ring and a primary plunger retaining ring are provided between the primary plunger and the inner wall of the hydraulic cylinder, and a secondary plunger sealing ring and a secondary plunger retaining ring are provided between the secondary plunger and the inner wall of the primary plunger; a plunger retaining spring is provided at the bottom of the primary plunger to prevent the secondary plunger from contacting the bottom of the hydraulic cylinder and to form an oil buffer chamber; the plunger locking cap is fixed to the thread on the top of the hydraulic cylinder by threads.

5. The triaxial stress measuring device for coal and rock mass according to claim 1, characterized in that, The number of sections of the multi-section plunger is ≥2, and can be adjusted according to the borehole diameter to meet the measurement needs of boreholes of different sizes.

6. The triaxial stress measuring device for coal and rock mass according to claim 1, characterized in that, The self-locking anchor claw structure includes a self-locking ring and an anchor claw disc; The self-locking ring is annular, with a diameter matching the stress gauge. It is welded to the axial tail of the cylindrical structure and has a pre-reserved notch on one side for the oil pipe to pass through. A wedge-shaped self-locking buckle is provided on the inner side of the self-locking ring, which matches the bottom of the anchor claw plate. At least three anchor claws are evenly distributed on the anchor claw disc, and a steel wire rope is connected to the anchor claw disc and extends to the outside of the borehole.

7. A triaxial stress measurement system for coal and rock mass, characterized in that, Includes a coal and rock mass triaxial stress measuring device as described in any one of claims 1-6.

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