A method for detecting and evaluating sensitivity of an online sensor for rock burst stress

Abstract

A method for detecting and evaluating the sensitivity of an online stress sensor for rockburst includes the following steps: First, determine the drilling area based on the on-site equipment layout and construction conditions. Second, arrange multiple coal blasting holes and online stress sensor mounting holes within the drilling area, installing multiple online stress sensors at the same depth within each mounting hole. Third, load explosives into each blasting hole, connect and seal the holes, and after valid testing of the online stress sensor data, implement coal blasting. Fourth, monitor the stress values ​​and response times generated during coal blasting using the online stress sensors. Fifth, determine the sensitivity of the online stress sensors based on the changes observed at the same depth within the same mounting hole during coal blasting, and evaluate the effectiveness level. This method can alter the stress state of the surrounding rock in the roadway, evaluate the sensitivity of different sensor models at the same location, select the optimal stress sensor, and improve monitoring efficiency.

Description

Technical Field

[0001] This invention relates to a method for detecting and evaluating the sensitivity of an online rockburst stress sensor, belonging to the field of coal mine safety mining technology. Background Technology

[0002] With the increasing intensity and depth of coal mining, the deterioration of the stress environment in resource storage has led to frequent rockbursts, severely restricting safe production in coal mines. Effective monitoring and early warning technologies have become crucial to effectively curb rockbursts. In recent years, rockburst monitoring and early warning have developed towards regionalization, continuity, and diversification, with various monitoring devices and methods such as microseismic, acoustic emission, and electromagnetic radiation emerging. For stress monitoring in rockburst-prone areas, the current methods mainly include the drill cuttings method and online stress monitoring. The drill cuttings method is primarily used for monitoring stress points within roadways, while online stress monitoring focuses on linear stress monitoring within the leading range of the two roadways in the working face.

[0003] Numerous online stress monitoring devices exist, and their deployment methods vary widely beyond relevant regulations. Many mines, especially those prone to rock bursts and other hazards, have installed online stress monitoring systems. However, due to differences in roadway mining and geological factors, the distribution characteristics of coal and rock stress differ. Therefore, the placement of downhole and deep boreholes for online stress monitoring should also vary depending on the coal pillar or the actual coal conditions at the working face. Consequently, the current use of the same deployment method for monitoring roadways with different conditions needs improvement.

[0004] Given the complex stress environment at the site, existing methods for altering the stress state of the surrounding rock mainly include coal blasting and large-diameter drilling. However, no corresponding detection and evaluation methods have been developed for the sensitivity of online stress sensors, which prevents the online stress monitoring system from fully utilizing its monitoring capabilities. Summary of the Invention

[0005] This invention provides a method for detecting and evaluating the sensitivity of an online rockburst stress sensor. This method can change the stress state of the surrounding rock in a roadway and evaluate the sensitivity of different types of sensors at the same location, thereby selecting the optimal stress sensor and improving monitoring efficiency.

[0006] To achieve the above objectives, the present invention provides a method for detecting and evaluating the sensitivity of an online rockburst stress sensor, comprising the following steps:

[0007] (1) Based on the on-site equipment layout and construction conditions, determine the detection borehole layout area, that is, using the known borehole parameters, sensor layout method and sensor model, arrange stress online sensor installation boreholes and coal blasting boreholes perpendicular to the coal body on the side of the roadway solid coal at a distance a from the advance working face.

[0008] (2) In the detection borehole layout area determined in step (1), coal body blasting hole groups and multiple stress online sensor installation hole groups are arranged along the roadway direction. Multiple coal body blasting holes are arranged in the coal body blasting hole group. The distance between each coal body blasting hole and the first stress online sensor installation hole that is closest to the roadway direction is not less than 5m. Multiple stress online sensor installation holes are arranged in each stress online sensor installation hole group. The spacing between adjacent stress online sensor installation holes is b. Multiple stress online sensors are arranged at the same depth position in each stress online sensor installation hole. The horizontal distance between the location of each stress online sensor and the opening of the stress online sensor installation hole is c.

[0009] (3) Install different types of online stress sensors to the designated positions of the online stress sensor installation holes determined in step (2); load explosives, connect wires, and seal the coal blasting holes laid out in step (2). At the same time, after effectively testing the data monitoring of the installed online stress sensors, implement coal blasting. The blasting is carried out in the order from farthest to near the online stress sensors. Monitor the stress values ​​generated by the online stress sensors in each installation hole in real time to obtain the stress values ​​generated by all online stress sensors during the blasting. and response time ;

[0010] (4) Determine the sensitivity of the stress online sensor based on the changes in the stress online sensor of different models placed at the same depth in the same stress online sensor mounting hole during the coal blasting process: the stress value obtained in step (3) and response time The analysis and processing were performed to statistically analyze the stress changes at different locations within the same online stress sensor mounting hole during each coal blasting operation. and stress change time The ratio of the stress changes is used to determine the rate of stress change. Its expression is: The unit is MPa / min; the online stress sensor with the highest stress change rate is the most sensitive sensor.

[0011] (5) The effectiveness of the online stress sensor in monitoring stress changes is evaluated based on its sensitivity. The evaluation standard for the sensitivity of the online stress sensor is as follows: when... When the pressure is <0.05 MPa / min, the sensitivity rating of the online stress sensor is poor; when 0.05 MPa / min ≤ When the pressure is <0.1 MPa / min, the sensitivity rating of the online stress sensor is medium; when 0.1 MPa / min ≤ When the stress is <0.5 MPa / min, the sensitivity evaluation level of the online stress sensor is good; when When the pressure is ≥0.5MPa / min, the sensitivity evaluation level of the stress sensor is excellent.

[0012] Furthermore, in step (1), the distance a from the advanced working face is ≥200m; the area for the detection borehole layout is convenient for drilling construction and is not affected by factors such as conveyor belts and substation equipment.

[0013] Furthermore, in step (2), at least 5 coal blasting holes are arranged in the coal blasting hole group. The distances between each coal blasting hole and the first stress online sensor installation hole that is closest to the roadway direction are 90~100m, 40~50m, 20~30m, 8~10m, and 3~5m, respectively. The hole diameter is 70~80mm, the drilling depth is 13~15m, the distance from the roadway floor is 1~1.2m, the charge length is 2~3m, and the sealing length is 2~3m.

[0014] Each stress online sensor mounting hole group shall have at least 3 stress online sensor mounting holes, and each stress online sensor mounting hole shall have at least 2 stress online sensors of different models. The spacing b between adjacent stress online sensor mounting holes shall be 20~25m, the hole depth shall be 12~14m, the distance from the roadway floor shall be 1~1.2m, and the horizontal height shall be consistent with the coal blasting hole. The horizontal distance c between the location of each stress online sensor and the opening of the stress online sensor mounting hole shall be 12~14m.

[0015] This invention determines a suitable area for detecting coal seams, facilitating construction and unaffected by equipment limitations. Within this area, multiple coal seam blasting holes and multiple stress online sensor mounting holes are arranged. Different types of stress online sensors are installed at the same depth within each stress online sensor mounting hole. The coal seam is blasted sequentially from far to near to alter its stress state. Simultaneously, the stress online sensors monitor the stress changes and response times before and after blasting. Based on the stress changes and response times monitored by different stress online sensors at the same depth within the same stress online sensor mounting hole, the stress change rate is calculated. This allows for the determination of the optimal stress online sensor at the same depth within the same stress online sensor mounting hole, thus identifying the optimal sensor. This invention effectively determines the optimal stress online sensor within the same stress online sensor mounting hole, significantly improving the monitoring efficiency of the sensors. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the layout of coal blasting holes and stress online sensor installation holes in an embodiment of the present invention;

[0017] Figure 2This is a stress change rate curve after blasting is carried out at a distance of 100 m from the stress online sensor installation hole in the coal body in an embodiment of the present invention;

[0018] Figure 3 This is a stress change rate curve after blasting is carried out at a distance of 50 m from the stress online sensor installation hole in the coal body in an embodiment of the present invention;

[0019] Figure 4 This is a stress change rate curve after blasting is carried out at a distance of 30 m from the stress online sensor installation hole in the coal body in an embodiment of the present invention;

[0020] Figure 5 This is a stress change rate curve after blasting is carried out at a distance of 10m from the stress online sensor installation hole in the coal body in an embodiment of the present invention;

[0021] Figure 6 This is a curve showing the rate of stress change after blasting is performed at a distance of 5m from the stress online sensor mounting hole in the coal body, as described in this embodiment of the invention. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] A method for sensitivity detection and evaluation of an online rockburst stress sensor includes the following steps:

[0024] (1) Based on the on-site equipment layout and construction conditions, determine the detection borehole layout area, that is, using the known borehole parameters, sensor layout method and sensor model, arrange stress online sensor installation boreholes and coal blasting boreholes perpendicular to the coal body on the side of the roadway solid coal at a distance a from the advance working face.

[0025] (2) In the detection borehole layout area determined in step (1), coal body blasting hole groups and multiple stress online sensor installation hole groups are arranged along the roadway direction. Multiple coal body blasting holes are arranged in the coal body blasting hole group. The distance between each coal body blasting hole and the first stress online sensor installation hole that is closest to the roadway direction is not less than 5m. Multiple stress online sensor installation holes are arranged in each stress online sensor installation hole group. The spacing between adjacent stress online sensor installation holes is b. Multiple stress online sensors are arranged at the same depth position in each stress online sensor installation hole. The horizontal distance between the location of each stress online sensor and the opening of the stress online sensor installation hole is c.

[0026] (3) Install different types of online stress sensors to the designated positions of the online stress sensor installation holes determined in step (2); load explosives, connect wires, and seal the coal blasting holes laid out in step (2). At the same time, after effectively testing the data monitoring of the installed online stress sensors, implement coal blasting. The blasting is carried out in the order from farthest to near the online stress sensors. Monitor the stress values ​​generated by the online stress sensors in each installation hole in real time to obtain the stress values ​​generated by all online stress sensors during the blasting. and response time ;

[0027] (4) Determine the sensitivity of the stress online sensor based on the changes in the stress online sensor of different models placed at the same depth in the same stress online sensor mounting hole during the coal blasting process: the stress value obtained in step (3) and response time The analysis and processing were performed to statistically analyze the stress changes at different locations within the same online stress sensor mounting hole during each coal blasting operation. and stress change time The ratio of the stress changes is used to determine the rate of stress change. Its expression is: The unit is MPa / min; the sensor with the highest rate of stress change is the most sensitive sensor.

[0028] (5) The effectiveness of the online stress sensor in monitoring stress changes is evaluated based on its sensitivity. The evaluation standard for the sensitivity of the online stress sensor is as follows: when... When the pressure is <0.05 MPa / min, the sensitivity rating of the online stress sensor is poor; when 0.05 MPa / min ≤ When the pressure is <0.1 MPa / min, the sensitivity rating of the online stress sensor is medium; when 0.1 MPa / min ≤ When the stress is <0.5 MPa / min, the sensitivity evaluation level of the online stress sensor is good; when When the pressure is ≥0.5MPa / min, the sensitivity evaluation level of the stress sensor is excellent.

[0029] In a preferred embodiment, the distance a from the working face in step (1) is ≥200m; the area for the detection borehole layout is convenient for drilling construction and is not affected by factors such as conveyor belts and substation equipment.

[0030] In a preferred embodiment, in step (2), at least 5 coal blasting holes are arranged in the coal blasting hole group. The distances between each coal blasting hole and the first stress online sensor installation hole that is closest to the roadway direction are 90~100m, 40~50m, 20~30m, 8~10m, and 3~5m, respectively. The hole diameter is 70~80mm, the drilling depth is 13~15m, the distance from the roadway floor is 1~1.2m, the charge length is 2~3m, and the sealing length is 2~3m.

[0031] Each stress online sensor mounting hole group shall have at least 3 stress online sensor mounting holes, and each stress online sensor mounting hole shall have at least 2 stress online sensors of different models. The spacing b between adjacent stress online sensor mounting holes shall be 20~25m, the hole depth shall be 12~14m, the distance from the roadway floor shall be 1~1.2m, and the horizontal height shall be consistent with the coal blasting hole. The horizontal distance c between the location of each stress online sensor and the opening of the stress online sensor mounting hole shall be 12~14m.

[0032] Example:

[0033] This implementation case focuses on determining the optimal online stress sensor for the 3308 working face of a certain mine. The mine has installed a microseismic monitoring system that can effectively surround the 3308 working face area and has high accuracy in monitoring microseismic events in the area.

[0034] (1) such as Figure 1 As shown, the optimal placement of online stress sensors was detected within a range of 200-360m ahead of the return air roadway of the 3308 working face. This area is free from interference from other equipment and is convenient for construction.

[0035] (2) Within the determined borehole detection area, coal blasting hole groups and multiple stress online sensor installation hole groups are set up along the roadway direction. Each coal blasting hole group has at least 5 coal blasting holes, and the distances to the first stress online sensor installation hole closest to the roadway direction are 100m, 50m, 30m, 10m, and 5m, respectively. Each stress online sensor installation hole group has 3 stress online sensor installation holes, and the distance between adjacent installation holes is 20m. Two stress online sensors of different models are installed at the same depth in each stress online sensor installation hole. The horizontal distance between the location of each stress online sensor and the opening of the stress online sensor installation hole is 14m.

[0036] The coal blasting holes are 75mm in diameter, 13m deep, with a charge length of 2m and a sealing length of 2m, connected in series within the forward-charging holes. After the online stress sensors are deployed and their monitoring data is verified, coal blasting is carried out. Blasting is conducted sequentially from farthest to closest to the online stress sensors. The stress change rate curves monitored by two different types of online stress sensors within each installation hole are shown in the figure below. Figures 2 to 6 As shown;

[0037] (3) Use the installed and tested online stress sensors to monitor the changes in the sensors during each coal blasting operation, including stress change values. and stress change time Then, the rate of stress change can be obtained. The unit is MPa / min; the sensitivity evaluation criterion is the rate of stress change. <0.05MPa / min, 0.05MPa / min≤ <0.1MPa / min, 0.1MPa / min≤ <0.5MPa / min ≥0.5MPa / min, corresponding to evaluation levels of poor, average, good, and excellent, respectively. The evaluation results are shown in Table 1.

[0038] Table 1. Sensitivity Evaluation Table for Online Stress Sensors

[0039] .

Claims

1. A method for detecting and evaluating the sensitivity of an online sensor of rockburst stress, characterized in that, Includes the following steps: (1) Based on the on-site equipment layout and construction conditions, determine the detection borehole layout area, that is, using the known borehole parameters, sensor layout method and sensor model, arrange stress online sensor installation boreholes and coal blasting boreholes perpendicular to the coal body on the side of the roadway solid coal at a distance a from the advance working face. (2) In the detection borehole layout area determined in step (1), coal body blasting hole groups and multiple stress online sensor installation hole groups are arranged along the roadway direction. Multiple coal body blasting holes are arranged in the coal body blasting hole group. The distance between each coal body blasting hole and the first stress online sensor installation hole that is closest to the roadway direction is not less than 5m. Multiple stress online sensor installation holes are arranged in each stress online sensor installation hole group. The spacing between adjacent stress online sensor installation holes is b. Multiple stress online sensors are arranged at the same depth position in each stress online sensor installation hole. The horizontal distance between the location of each stress online sensor and the opening of the stress online sensor installation hole is c. (3) Install different types of online stress sensors to the designated positions of the online stress sensor installation holes determined in step (2); load explosives, connect wires, and seal the coal blasting holes laid out in step (2). At the same time, after effectively testing the data monitoring of the installed online stress sensors, implement coal blasting. The blasting is carried out in the order from farthest to near the online stress sensors. Monitor the stress values ​​generated by the online stress sensors in each installation hole in real time to obtain the stress values ​​generated by all online stress sensors during the blasting. and response time ; (4) Determine the sensitivity of the stress online sensor based on the changes in the stress online sensor of different models placed at the same depth in the same stress online sensor mounting hole during the coal blasting process: the stress value obtained in step (3) and response time The analysis and processing were performed to statistically analyze the stress changes at different locations within the same online stress sensor mounting hole during each coal blasting operation. and stress change time The ratio of the stress changes is used to determine the rate of stress change. Its expression is: The unit is MPa / min; the sensor with the highest rate of stress change is the most sensitive sensor. (5) The effectiveness of the online stress sensor in monitoring stress changes is evaluated based on its sensitivity. The evaluation standard for the sensitivity of the online stress sensor is as follows: when... When the pressure is less than 0.05 MPa / min, the sensitivity rating of the online stress sensor is poor. When 0.05MPa / min≤ When the pressure is less than 0.1 MPa / min, the sensitivity evaluation level of the online stress sensor is medium. When 0.1 MPa / min ≤ <0.5 MPa / min, the sensitivity of the stress in-line sensor is evaluated as good; when ≥ 0.5 MPa / min, the sensitivity of the stress sensor is evaluated as excellent.

2. The method for detecting and evaluating the sensitivity of an in-situ stress sensor according to claim 1, wherein, In step (1), the distance a from the advanced working face is ≥200m; the area for the detection borehole layout is convenient for drilling construction and is not affected by factors such as conveyor belts and substation equipment.

3. The method for detecting and evaluating the sensitivity of an in-situ stress sensor according to claim 1, wherein, In step (2), at least 5 coal blasting holes are arranged in the coal blasting hole group. The distances between each coal blasting hole and the first stress online sensor installation hole that is closest to the roadway direction are 90~100m, 40~50m, 20~30m, 8~10m, and 3~5m, respectively. The hole diameter is 70~80mm, the drilling depth is 13~15m, the distance from the roadway floor is 1~1.2m, the charge length is 2~3m, and the sealing length is 2~3m. Each stress online sensor mounting hole group shall have at least 3 stress online sensor mounting holes, and each stress online sensor mounting hole shall have at least 2 stress online sensors of different models. The spacing b between adjacent stress online sensor mounting holes shall be 20~25m, the hole depth shall be 12~14m, the distance from the roadway floor shall be 1~1.2m, and the horizontal height shall be consistent with the coal blasting hole. The horizontal distance c between the location of each stress online sensor and the opening of the stress online sensor mounting hole shall be 12~14m.

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