A mine drilling rig while-drilling monitoring device and a coal body stress measuring method

Abstract

The present application provides a kind of mine drilling rig while drilling monitoring device and coal stress determination method, it is related to mining equipment and measurement technical field, the device includes drilling rig, drill pipe, data monitoring system, data acquisition device and explosion-proof box, the power head of drilling rig is connected front end coupling, torque speed sensor is connected with front end coupling and rear end coupling respectively;Data monitoring system includes pull rope displacement sensor and torque speed sensor, pull rope sensor one end is connected with the below of power head, the other end is connected with drilling rig support;Data acquisition device includes data acquisition instrument and explosion-proof mobile phone, for processing monitoring data.Using the device on the basis of pressure-relief drilling, through while drilling monitoring system obtains drilling time, displacement, torque and speed and other drilling parameters in drilling process, determines drilling speed and unit depth drilling energy by calculation, and then obtains coal stress, and the change rule of coal stress in drilling process.

Description

Technical Field

[0001] This invention relates to the field of mining equipment and measurement technology, specifically to a drilling monitoring device for mining rigs and a method for measuring coal stress. Background Technology

[0002] High stress and energy accumulation in coal seams are the main causes of rockbursts. Real-time acquisition of dynamic data on coal seam stress is a key link in rockburst early warning and prevention. Large-diameter borehole stress relief is one of the commonly used stress relief methods, but existing technologies cannot directly obtain coal seam stress. In order to accurately prevent the occurrence of rockbursts, obtaining the distribution and variation law of coal seam stress has become an urgent need for developing green and intelligent mines and improving safety production capabilities.

[0003] As coal resources are mined at greater depths, the complex geological environment characterized by high ground stress, high osmotic pressure, and high ground temperature causes coal and rock to release a large amount of energy, inducing rockbursts. Studies have shown that high stress and stress concentration in the coal body play a major controlling role in the occurrence of rockbursts. Real-time acquisition of coal body stress is a key link in rockburst early warning, but existing in-situ stress testing methods are insufficient to meet the needs of detecting the stress distribution pattern in the coal body.

[0004] Large-diameter pressure relief boreholes are an important means of preventing rockbursts, offering advantages such as low construction difficulty and significant pressure relief effects. This technology is widely used in various coal mines, with cumulative drilling depths reaching hundreds of thousands of meters annually. This construction process generates continuous and abundant drilling data, primarily including drilling parameters such as drilling speed, rotational speed, drilling pressure, and torque. This data contains a wealth of geological information, yet it has not received sufficient attention. However, similar data is widely used in fields such as oil well logging and tunnel exploration.

[0005] Measurement while drilling (MSW) is a technique that collects drilling data at a specific frequency during the drilling process. Traditional measurement methods during drilling involve "stop-drilling" measurements, where the drill string is removed and a measuring device is installed for data collection. This method has limitations such as complex operation, high cost, low testing frequency, and long cycle time. MSW overcomes these shortcomings by allowing real-time monitoring of the drilling rig's response parameters and dynamic phenomena during drilling, analyzing the relationship between drilling parameters and coal stress, and determining coal stress by monitoring drilling parameters. However, current research has not yielded a clear relationship between coal stress and drilling parameters. Further improvements to the methods for measuring coal stress are needed for accurate measurement. Summary of the Invention

[0006] In order to achieve real-time acquisition of drilling parameters such as torque, rotation speed, and drilling displacement during large-diameter pressure relief drilling, and to determine the variation law of coal stress during drilling, this invention provides a mining drilling rig monitoring device and a coal stress measurement method, the specific technical solution of which is as follows.

[0007] A drilling rig monitoring device includes a drilling rig, drill rod, data monitoring system, data acquisition device, and explosion-proof enclosure. The data monitoring system includes a cable displacement sensor and a torque-speed sensor. One end of the cable sensor is connected to the bottom of the power head, and the other end is connected to the drilling rig support. The power head of the drilling rig is connected to a front coupling, and the torque-speed sensor is connected to both the front and rear couplings. The data acquisition device includes a data acquisition unit and an explosion-proof mobile phone. The data acquisition unit has a built-in Bluetooth transmission module and is connected to the data monitoring system. The data acquisition unit transmits the acquired data to the explosion-proof mobile phone via the Bluetooth transmission module. The explosion-proof mobile phone then transmits the acquired drilling rig parameters to the ground monitoring host via an underground fiber optic switch.

[0008] Preferably, the power head is connected to the front coupling via a male and female connector, the rear coupling is connected to the drill pipe via a male and female connector, and the front coupling is connected to the torque and speed sensor via a keyway.

[0009] Preferably, the drilling rig is a mining crawler-type fully hydraulic tunnel drilling rig, equipped with a dual-pump system, with independent adjustment of the drilling rig's rotation and feed parameters, and stepless adjustment of the variable oil pump and variable motor.

[0010] Preferably, the torque and speed sensor has a maximum range of 1500 N·m and a speed range of 300 r / min; the data acquisition instrument and power supply battery are placed in an explosion-proof box.

[0011] A method for determining coal seam stress while drilling using a mining drilling rig, utilizing the aforementioned monitoring device for while drilling, includes the following steps:

[0012] S1. Perform a force balance analysis on the cutting edge of the drill bit along the x and y directions to determine the relationship between the drilling torque and the anti-drilling force;

[0013] S2. Perform stress analysis on the fracture surface of the coal body to determine the relationship between the normal force and the tangential force on the fracture surface, and to determine the relationship between the normal stress and the shear stress on the fracture surface;

[0014] S3. Shear failure occurs along the coal fracture surface. Using Mohr-Coulomb theory as the coal breaking condition, the relationship between rock cohesion and the tangential and normal forces on the cutting tool is determined.

[0015] S4. Using trigonometric functions and the product of sums and differences, we obtain the functional expressions for the drilling resistance force, rock parameters, drill bit parameters, and coal stress. By differentiating this relationship, we find that the drilling resistance force reaches its maximum value on the fracture surface at a certain inclination angle. Then, we obtain the relationship between the coal stress and the maximum value of the drilling resistance force, and further obtain the relationship between drilling pressure, cutting force, and coal stress. Finally, through the relationship between torque and cutting force, we obtain the relationship between coal stress and torque.

[0016] S5. The coal stress is determined by collecting torque, rotational speed, drilling speed, coal material parameters, and drill bit size parameters from the measurement-while-drilling (MWD) monitoring system. This process includes the following steps:

[0017] S51. After determining the pressure relief location of the large-diameter borehole, adjust and test the monitoring device while drilling for the mining rig;

[0018] S52. The drilling rig is positioned at the designated location, the drilling angle is adjusted, and the hole is opened;

[0019] S53. Replace the drill rod. The pull rope displacement sensor is fixed below the power head of the drill rig and moves back and forth with the power head. The starting end of the pull rope is fixed on the support of the drill rig and does not change position with the movement of the power head. The drill rig, torque and speed sensor and drill rod are fixed as a whole. Adjust the position of the explosion-proof box.

[0020] S54. Start the drilling rig, continuously connect new drill rods and complete drilling. Record the power phenomena of the drilling rig during the drilling process, and the data acquisition instrument records the monitoring data.

[0021] S55. After drilling is completed, analyze the variation of drilling parameters and calculate the stress in the coal seam.

[0022] Preferably, the relationship between drilling pressure torque and drilling resistance force is as follows:

[0023]

[0024]

[0025] Among them, F a 'For drilling pressure, F t For cutting force, F s F is the frictional resistance that the drill bit experiences from the coal and rock. n To resist drilling force, θ is the angle between the direction of the drilling force and the vertical plane of the drill bit, and θ is the tool half-angle.

[0026] Preferably, the relationship between the normal force and the tangential force on the coal fracture surface is as follows:

[0027]

[0028] The relationship between the normal stress and shear stress on the fracture surface is as follows:

[0029]

[0030]

[0031] Where R is the total normal force on the fracture surface, S is the total tangential force on the fracture surface, α is the angle between the fracture surface and the horizontal plane, and F... σ Additional force on the coal body, N R W represents the normal force on the fracture surface caused by the reaction force of the drill bit on the coal body. R R0 is the normal force on the fracture surface caused by the tangential force of the coal body subjected to the reaction force from the drill bit, and R1 is the normal force on the fracture surface caused by the additional force on the coal body. (N) S W represents the tangential force on the fracture surface caused by the normal force exerted on the coal seam by the reaction force from the drill bit. S S1 is the tangential force on the fracture surface caused by the reaction force of the drill bit on the coal body, σ is the normal stress on the fracture surface, τ is the shear stress on the fracture surface, L is the length of the fracture surface, b is the width of the cutting edge, and h is the depth of tool penetration.

[0032] Preferably, the relationship between the rock cohesion and the tangential and normal forces acting on the cutting tool is as follows:

[0033]

[0034] Where φ is the internal friction angle of the coal and rock, c is the cohesive force of the coal body, W is the tangential force of the cutting tool, and N is the normal force of the cutting tool.

[0035] Preferably, the functional expression for the anti-drilling force is:

[0036]

[0037] The functional expression for the cutting force is:

[0038]

[0039] The functional expression for the stress in the coal seam is:

[0040]

[0041] Where M a Let σ be the torque during drilling, n be the rotational speed, v be the drilling speed, R' be the distance from the drill bit tip to the centerline, and σ be the torque during drilling. b Let μ be the strength of the coal and rock, and μ1 be the coefficient of friction between the blade and the coal and rock. σ0 is the angle between the direction of the drilling force and the vertical plane of the drill bit, and σ0 is the stress in the coal body.

[0042] The parameters ξ1, ξ2, and ξ4 are calculated as follows:

[0043]

[0044]

[0045]

[0046] The stress σ0 of the coal body is calculated and determined.

[0047] Preferably, the drilling speed and drilling energy per unit depth are calculated and determined by using drilling time, displacement, torque, rotational speed and drill bit and drill rod parameters during the drilling process, and the stress changes in the coal seam during the drilling process are determined.

[0048] The beneficial effects of the mining drilling rig monitoring device and coal stress determination method provided by this invention are as follows: By improving the structure of drill rods and other components, real-time acquisition of drilling data can be achieved without affecting the working efficiency of the drilling rig; the drilling rig and other equipment are easy to operate, highly automated, and can accurately reflect the drilling process; the coal stress can be determined by drilling time, displacement, torque, rotation speed, and drill bit and drill rod parameters with higher accuracy and smaller error, providing data support for on-site coal breaking drilling construction. Attached Figure Description

[0049] Figure 1 This is a stress analysis diagram of the drill bit;

[0050] Figure 2 This is a diagram showing the resultant force analysis of the coal seam;

[0051] Figure 3 This is a stress analysis diagram of the coal seam fracture surface;

[0052] Figure 4 This is a schematic diagram of the structure of the monitoring device for mining drilling rigs.

[0053] Figure 5 This is a schematic diagram of the internal structure of the explosion-proof box;

[0054] Figure 6 This is a schematic diagram of the installation structure of the torque and speed sensor;

[0055] Figure 7 A schematic diagram of the structure of a pull-string displacement sensor;

[0056] Figure 8 This is a diagram of the data transmission path;

[0057] Figure 9 This is a schematic diagram illustrating the principle of coal stress measurement.

[0058] In the diagram: 1-Drilling rig, 2-Power head, 3-Coupling, 4-Torque and speed sensor, 5-Drill rod, 6-Drill bit, 7-Wire rope displacement sensor, 8-Drilling rig slide rail, 9-Drilling rig support, 10-Downhole fiber optic switch, 11-Ground monitoring host, 12-Explosion-proof box, 13-Lithium battery, 14-Fixing key, 15-Data acquisition instrument, 16-Bluetooth transmission module, 17-Explosion-proof mobile phone, 18-Data processing software. Detailed Implementation

[0059] Combination Figures 1 to 9 The following describes a specific implementation of the drilling monitoring device for mining rigs and the method for measuring coal stress provided by the present invention.

[0060] A drilling rig monitoring device includes a drilling rig 1, drill rod 5, a data monitoring system, a data acquisition device, and an explosion-proof enclosure. It can monitor drilling time, drilling displacement, torque, and rotational speed in real time, and calculate drilling parameters such as drilling speed and drilling energy. The data monitoring system includes a cable displacement sensor and a torque / speed sensor. One end of the cable sensor is connected to the bottom of the power head, and the other end is connected to the drilling rig support. The power head 2 of the drilling rig 1 is connected to a front coupling, and the torque / speed sensor 4 is connected to both the front and rear couplings. The data acquisition device includes a data acquisition unit 15 and an explosion-proof mobile phone 17. The data acquisition unit 15 has a built-in Bluetooth transmission module and connects to the data monitoring system. The data acquisition unit 15 transmits the collected data to the explosion-proof mobile phone 17 via the Bluetooth transmission module. The explosion-proof mobile phone 17 then transmits the collected drilling rig parameters to the surface monitoring host via a downhole fiber optic switch.

[0061] The power head 2 is connected to the front coupling via a male and female connector, the rear coupling is connected to the drill pipe via a male and female connector, and the front coupling is connected to the torque and speed sensor 4 via a keyway.

[0062] Drilling rig 1 is a tracked, fully hydraulic tunnel drilling rig for mining. Drilling rig 1 is equipped with a dual-pump system, and the rotation parameters and feed process parameters can be adjusted independently. The combination of variable oil pump and variable motor can be infinitely adjusted, and the speed and torque can be varied over a wide range, which improves the adaptability of the drilling rig to different drilling processes. It can drill 360° fully automatically, and the tracks can be controlled independently, making turning and turning convenient.

[0063] The torque and speed sensor 4 has a maximum range of 1500 N·m and a speed range of 300 r / min. It can monitor both torque and speed parameters in real time during large-diameter pressure relief drilling. The sensor is equipped with couplings at both ends that match the drilling rig's power head and drill rod. The torque and speed sensor 4, the two couplings 3, and the drill rod 5 are machined into a non-standard drill rod with measurement capabilities. The cable displacement sensor measures the drilling displacement by monitoring the relative displacement between the drilling rig support and the power head, and calculates the total drilling depth by accumulating these measurements.

[0064] The data acquisition unit 15 and the power supply battery are placed in an explosion-proof box. The battery is a lithium battery 13. The data monitoring system is explosion-proof to adapt to the flammable and explosive environment underground. It can realize the transmission and conversion of underground electrical signals. At the same time, the range settings of each sensor have been changed to better meet the usage standards of the engineering site.

[0065] A method for determining coal seam stress while drilling using a mining drilling rig, utilizing the aforementioned monitoring device for while drilling, includes the following steps:

[0066] S1. Perform a force balance analysis on the cutting edge of the drill bit along the x and y directions. Based on the force analysis of one cutting edge of a large-diameter pressure-relief drill bit (φ150×F32 alloy anti-blow drill bit), determine the relationship between drilling torque and drilling resistance force.

[0067] The relationship between drilling pressure torque and drilling resistance force is as follows:

[0068]

[0069]

[0070] Among them, F a 'For drilling pressure, F t For cutting force, F s F is the frictional resistance that the drill bit experiences from the coal and rock. n To resist drilling force, θ is the angle between the direction of the drilling force and the vertical plane of the drill bit, and θ is the tool half-angle.

[0071] S2. Perform stress analysis on the fracture surface of the coal body to determine the relationship between the normal force and the tangential force on the fracture surface, and to determine the relationship between the normal stress and the shear stress on the fracture surface;

[0072] The relationship between the normal force and the tangential force on the fracture surface of the coal body is as follows:

[0073]

[0074] The relationship between normal stress and shear stress on the fracture surface is as follows:

[0075]

[0076]

[0077] Where R is the total normal force on the fracture surface, S is the total tangential force on the fracture surface, α is the angle between the fracture surface and the horizontal plane, and F... σ Additional force on the coal body, N R W represents the normal force on the fracture surface caused by the reaction force of the drill bit on the coal body. R R0 is the normal force on the fracture surface caused by the tangential force of the coal body subjected to the reaction force from the drill bit, and R1 is the normal force on the fracture surface caused by the additional force on the coal body. (N) S W represents the tangential force on the fracture surface caused by the normal force exerted on the coal seam by the reaction force from the drill bit. S S1 is the tangential force on the fracture surface caused by the reaction force of the drill bit on the coal body, σ is the normal stress on the fracture surface, τ is the shear stress on the fracture surface, L is the length of the fracture surface, b is the width of the cutting edge, and h is the depth of tool penetration.

[0078] S3. Shear failure occurs along the coal fracture surface. Using Mohr-Coulomb theory as the coal breaking condition, the relationship between rock cohesion and the tangential and normal forces on the cutting tool is determined.

[0079] The relationship between the rock cohesion and the tangential and normal forces acting on the cutting tool is as follows:

[0080]

[0081] Where φ is the internal friction angle of the coal and rock, c is the cohesive force of the coal body, W is the tangential force of the cutting tool, and N is the normal force of the cutting tool.

[0082] S4. Using trigonometric functions and the product of sums and differences, we obtain the functional expressions for the drilling resistance force, rock parameters, drill bit parameters, and coal stress. By differentiating this relationship, we find that the drilling resistance force reaches its maximum value on the fracture surface at a certain inclination angle. Then, we obtain the relationship between the coal stress and the maximum value of the drilling resistance force, and further obtain the relationship between drilling pressure, cutting force, and coal stress. Finally, through the relationship between torque and cutting force, we obtain the relationship between coal stress and torque.

[0083] The functional expression for the anti-drilling force is:

[0084]

[0085] The functional expression for cutting force is:

[0086]

[0087] The functional expression for coal body stress is:

[0088]

[0089] Where M a Let σ be the torque during drilling, n be the rotational speed, v be the drilling speed, R' be the distance from the drill bit tip to the centerline, and σ be the torque during drilling. b Let μ be the strength of the coal and rock, and μ1 be the coefficient of friction between the blade and the coal and rock. σ0 is the angle between the direction of the drilling force and the vertical plane of the drill bit, and σ0 is the stress in the coal body.

[0090] The parameters ξ1, ξ2, and ξ4 are calculated as follows:

[0091]

[0092]

[0093]

[0094] The stress σ0 of the coal body is calculated and determined.

[0095] S5. The coal stress is determined by collecting torque, rotational speed, drilling speed, coal material parameters, and drill bit size parameters from the measurement-while-drilling (MWD) monitoring system. This process includes the following steps:

[0096] S51. After determining the pressure relief location for the large-diameter borehole, determine the model of the test drilling rig and the drill pipe diameter, as well as the accurate time for going downhole and the personnel involved. Next, fully charge the 24V lithium battery, adjust the torque speed sensor and the cable displacement sensor to a good working state, and connect them to the data acquisition instrument. Put the lithium battery and data acquisition instrument into working condition and place them in an explosion-proof box. The explosion-proof box must not be opened during the downhole operation. Machin a 0.5m long non-standard drill pipe to prevent situations where the working space is reduced due to the addition of the drilling monitoring system, making it impossible to properly connect and replace the 1m standard drill pipe.

[0097] Adjust and test the monitoring device while drilling on the mining drilling rig. Specifically, after arriving at the designated location, the operator moves the drilling rig to the designated drilling position, adjusts the drilling direction and angle, selects a drilling height of 1.5m from the bottom of the coal face, and positions the drilling rig in a suitable location between the production and non-production coal faces, leaving sufficient space for replacing the drill rod. The drilling rig support is raised to the top of the roadway to secure the drilling rig. The outer protective netting of the production coal face is cut, and the drilling rig is equipped with drill rods and drill bits to drill the hole. The drill bit is a diamond composite drill bit with a diameter of 120mm. After drilling, the drilling rig is stopped, and after checking that the drilling rig's working status is correct, the drilling rig adjustment is completed.

[0098] S52. The drilling rig is positioned at the designated location. The drilling angle is adjusted, and the hole is opened. After the drilling rig adjustment is completed, the drill rod used for opening the hole is removed, and the coal seam stress monitoring system is installed. The cable displacement sensor is fixed below the power head of the drilling rig and moves back and forth with the power head. The starting end of the cable is fixed to the support of the drilling rig and its position does not change with the movement of the power head. The two ends of the torque and speed sensor are connected to the coupling via keys and slots. The coupling connects the sensor and the drill rod, fixing the drilling rig, torque and speed sensor, and drill rod into a whole. Adding drill rods only requires connecting them at the rear end of the coupling. The explosion-proof box, which connects the displacement sensor and torque and speed sensor, and includes a data acquisition unit and a power supply, is placed in front of the drilling rig in a position that does not affect the normal operation of the drilling rig.

[0099] S53. Replace the drill rod. The pull rope displacement sensor is fixed below the power head of the drill rig and moves back and forth with the power head. The starting end of the pull rope is fixed on the support of the drill rig and does not change position with the movement of the power head. The drill rig, torque and speed sensor and drill rod are fixed as a whole. Adjust the position of the explosion-proof box.

[0100] S54. Start the drilling rig, continuously add new drill rods and complete drilling. Record the power phenomena of the drilling rig during drilling, and the data acquisition instrument records the monitoring data. After the preparation work is completed, restart the drilling rig, apply axial thrust and torque to the drill rod and drill bit. The front drill bit drills into the coal seam as the power head advances forward. When a drill rod is completely in the coal seam, the drilling rig stops, the operator disconnects the drill rod connected to the rear end of the coupling, the power head and the drilling monitoring system are withdrawn a sufficient distance along the slide rail, a new drill rod is added, and the drilling rig restarts to continue the drill rod advance and cutting work. This process is repeated until a 20m deep hole is completed. After all drill rods are drilled into the hole, the rod retraction begins, which is the reverse of the drilling process, until all drill rods are withdrawn from the coal seam, and one hole is completed. During the drilling process, any power phenomena such as drill bit suction, drill bit jamming, and coal bursting should be recorded in detail.

[0101] S55. After drilling is completed, analyze the variation patterns of drilling parameters and calculate the stress in the coal seam. After drilling is completed, clean up the coal dust discharged from the borehole and number the borehole. Remove the monitoring system while drilling, lower the roof support of drilling rig 1, and reset the drilling rig. The drilling parameters are transmitted to the ground monitoring host 11 via explosion-proof mobile phone 17 to query and process them, and export an Excel file. Combined with the on-site geological conditions and test records, analyze the variation patterns of drilling parameters and calculate the stress in the coal seam according to the formula.

[0102] By calculating the drilling time, displacement, torque, rotational speed, and drill bit and drill rod parameters during the drilling process, the drilling speed and drilling energy per unit depth are determined, and the stress changes in the coal seam during the drilling process are determined.

[0103] A drilling monitoring device for mining rigs and a method for measuring coal stress are disclosed. This device, through improvements to the drill rod and other structures, enables real-time acquisition of drilling data without affecting the drilling rig's efficiency. The drilling rig and other equipment are easy to operate, highly automated, and can accurately reflect the drilling process. The method for measuring coal stress using this device, which determines coal stress based on drilling time, displacement, torque, rotational speed, and drill bit and drill rod parameters, offers higher accuracy and smaller errors, providing data support for on-site coal breaking drilling operations.

[0104] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for determining coal seam stress during drilling using a mining drilling rig, comprising a monitoring device for monitoring coal seam stress during drilling, characterized in that... The system includes a drilling rig, drill pipe, data monitoring system, data acquisition device, and explosion-proof enclosure. The data monitoring system includes a cable displacement sensor and a torque-speed sensor. One end of the cable sensor is connected to the bottom of the power head, and the other end is connected to the drilling rig support. The power head of the drilling rig is connected to a front coupling, and the torque-speed sensor is connected to both the front and rear couplings. The data acquisition device includes a data acquisition unit and an explosion-proof mobile phone. The data acquisition unit has a built-in Bluetooth transmission module and is connected to the data monitoring system. The data acquisition unit transmits the acquired data to the explosion-proof mobile phone via the Bluetooth transmission module. The explosion-proof mobile phone then transmits the acquired drilling rig parameters to the ground monitoring host via a downhole fiber optic switch. The steps of the method include: S1. Perform a force balance analysis on the cutting edge of the drill bit along the x and y directions to determine the relationship between the drilling torque and the anti-drilling force; S2. Perform stress analysis on the fracture surface of the coal body to determine the relationship between the normal force and the tangential force on the fracture surface, and to determine the relationship between the normal stress and the shear stress on the fracture surface; S3. Shear failure occurs along the coal fracture surface. Using Mohr-Coulomb theory as the coal breaking condition, the relationship between rock cohesion and the tangential and normal forces on the cutting tool is determined. S4. Using trigonometric functions and the product of sums and differences, we obtain the functional expressions for the drilling resistance force, rock parameters, drill bit parameters, and coal stress. By differentiating this relationship, we find that the drilling resistance force reaches its maximum value on the fracture surface at a certain inclination angle. Then, we obtain the relationship between the coal stress and the maximum value of the drilling resistance force, and further obtain the relationship between drilling pressure, cutting force, and coal stress. Finally, through the relationship between torque and cutting force, we obtain the relationship between coal stress and torque. S5. The coal stress is determined by collecting torque, rotational speed, drilling speed, coal material parameters, and drill bit size parameters from the measurement-while-drilling (MWD) monitoring system. This process includes the following steps: S51. After determining the pressure relief location of the large-diameter borehole, adjust and test the monitoring device while drilling for the mining rig; S52. The drilling rig is positioned at the designated location, the drilling angle is adjusted, and the hole is opened; S53. Replace the drill rod. The pull rope displacement sensor is fixed below the power head of the drill rig and moves back and forth with the power head. The starting end of the pull rope is fixed on the support of the drill rig and does not change position with the movement of the power head. The drill rig, torque and speed sensor and drill rod are fixed as a whole. Adjust the position of the explosion-proof box. S54. Start the drilling rig, continuously connect new drill rods and complete drilling. Record the power phenomena of the drilling rig during the drilling process, and the data acquisition instrument records the monitoring data. S55. After drilling is completed, analyze the variation of drilling parameters and calculate and determine the stress in the coal body of the borehole; The functional expression for the anti-drilling force is: The functional expression for the cutting force is: The functional expression for the stress in the coal seam is: in M a This refers to the torque during the drilling process. n For rotational speed, v For drilling speed, R＇ This is the distance from the drill bit tip to the centerline. σ b For the strength of coal and rock, μ 1 The coefficient of friction between the blade and the coal / rock. The angle between the direction of the drilling force and the vertical plane of the drill bit. σ 0 For coal body stress; F t For cutting force, F n To resist drilling force, θ The cutting tool's half-angle; b The width of the cutting edge, h This refers to the depth of the cutting tool penetration. parameter ξ 1 , ξ 2 , ξ 4 The calculation method is as follows: in, The internal friction angle of coal and rock. с The internal cohesion of the coal body is used as the reference. The drilling speed and drilling energy per unit depth are calculated and determined by the drilling time, displacement, torque, rotation speed and drill bit and drill rod parameters during the drilling process, and the stress changes of the coal body during the drilling process are determined.

2. The method for determining coal seam stress using a mining drilling rig according to claim 1, characterized in that, The power head is connected to the front coupling via a male and female connector, the rear coupling is connected to the drill pipe via a male and female connector, and the front coupling is connected to the torque and speed sensor via a keyway.

3. The method for determining coal seam stress using a mining drilling rig according to claim 1, characterized in that, The drilling rig is a tracked, fully hydraulic tunnel drilling rig for mining. The rig is equipped with a dual-pump system, and the rig's rotation and feed parameters can be adjusted independently. The variable oil pump and variable motor can be infinitely adjusted.

4. The method for determining coal seam stress using a mining drilling rig according to claim 1, characterized in that, The torque and speed sensor has a maximum range of 1500 N•m and a speed range of 300 r / min; the data acquisition instrument and power supply battery are placed in an explosion-proof box.

5. The method for determining coal seam stress using a mining drilling rig according to claim 1, characterized in that, The relationship between the drilling torque and the drilling resistance force is as follows: in, F a ’ For drilling pressure, F s The frictional resistance experienced by the drill bit due to the coal and rock.

6. The method for determining coal seam stress using a mining drilling rig according to claim 5, characterized in that, The relationship between the normal force and the tangential force on the fracture surface of the coal body is as follows: The relationship between the normal stress and shear stress on the fracture surface is as follows: in R The total normal force on the fracture surface, S This represents the total tangential force on the fracture surface. F σ Adding force to the coal body, N R The normal force on the fracture surface is the normal force exerted on the coal body by the reaction force from the drill bit. W R R1 is the normal force on the fracture surface caused by the tangential force exerted on the coal body by the reaction force from the drill bit, and R2 is the normal force on the fracture surface caused by the additional force on the coal body. Ns The normal force exerted on the coal seam by the reaction force from the drill bit is the tangential force on the fracture surface. Ws This refers to the tangential force exerted on the fracture surface by the reaction force of the drill bit on the coal seam. S 1 The tangential force on the fracture surface represents the additional force on the coal body. σ The normal stress on the fracture surface, τ The shear stress on the fracture surface, L The length of the fracture surface.

7. The method for determining coal seam stress using a mining drilling rig according to claim 1, characterized in that, The relationship between the rock cohesion and the tangential and normal forces acting on the cutting tool is as follows: in, W The tangential force of the tool. N This is the normal force of the cutting tool.

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