A test hole first coal mine high stress area differentiation pressure relief method

Abstract

The application discloses a kind of test hole pre-arranged coal mine high stress area differentiation pressure relief method, steps include: obtaining mine geological survey data and ground stress test data, according to comprehensive index method, drill cuttings method, stress monitoring method determines high stress area roadway construction area;Large-diameter borehole test hole is arranged in roadway side, and stress high-low partition identification is carried out according to the construction completion condition of test hole;Different stress partition is taken corresponding pressure relief measure;Pressure relief effect evaluation is carried out to construction area, and pressure relief effect evaluation reaches set standard, then completes construction, otherwise, increase the density of borehole, until pressure relief effect reaches set standard.The application realizes differentiation pressure relief, and improves the pertinence, effectiveness and economy of rock burst prevention and control.

Description

Technical Field

[0001] This invention relates to a differentiated stress relief method for high-stress areas in coal mines using a test hole-first approach, belonging to the field of coal mine rockburst prevention technology. Background Technology

[0002] Coal mine rock bursts are dynamic disasters caused by the sudden release of energy from coal and rock masses under high stress. They are characterized by their suddenness, destructiveness, and unpredictability, seriously threatening safe coal mine production. With the increasing depth of coal seam mining in my country and the growing complexity of geological conditions, especially after entering the deep mining stage, the combined effects of high ground stress and mining-induced stress are significant, leading to an increasing frequency and intensity of rock bursts. Uneven stress distribution is commonly observed in high-stress areas: some sections have extremely high stress, making it easy to encounter problems such as necking, hole collapse, and stuck drill bits when directly drilling large-diameter boreholes, resulting in severely insufficient drilling depth; while other sections have relatively low stress, allowing for smoother drilling.

[0003] Existing stress relief technologies, when applied to high-stress areas in coal mines, often employ an experience-based construction approach with uniform hole layout and consistent parameters, lacking differentiated treatment for local stress peak and non-peak areas. This can easily lead to two problems: first, drilling may not be possible in high-stress, non-drillable areas, creating stress relief blind spots; second, excessive construction or unnecessary blasting may occur in low-stress, drillable areas, resulting in resource waste. Summary of the Invention

[0004] The purpose of this invention is to provide a differentiated stress relief method for high-stress areas in coal mines with test holes first. This method can achieve differentiated stress relief and improve the pertinence, effectiveness and economy of rockburst prevention and control.

[0005] To achieve the above objectives, the present invention provides a differentiated stress relief method for high-stress zones in coal mines with a test hole first, comprising the following steps:

[0006] S1. Obtain mine geological survey data and geostress test data, and determine the construction area of ​​roadway in high-stress zone based on comprehensive index method, drill cuttings method and stress monitoring method;

[0007] S2. Large-diameter test holes are laid out in the sidewalls of the roadway, and stress high and low zones are identified based on the completion status of the test holes.

[0008] S3. Take corresponding pressure relief measures for different stress zones;

[0009] S4. Evaluate the pressure relief effect in the construction area. If the pressure relief effect meets the set standard, the construction is completed; otherwise, increase the drilling density until the pressure relief effect meets the set standard.

[0010] Furthermore, the method for identifying high and low stress zones in S2 is as follows:

[0011] If the test hole reaches the designed depth, the area within 3-5m before and after the test hole is determined to be a low-stress zone; if the test hole fails to reach the designed depth due to high stress during drilling, the area within 3-5m before and after the test hole is determined to be a high-stress zone.

[0012] The test holes are spaced 6-10m apart, with a hole depth of not less than 25m and a borehole diameter of not less than 100mm. The borehole inclination angle is adjusted on-site according to the coal seam dip angle to ensure that the borehole is located within the designed pressure relief zone.

[0013] Furthermore, the pressure relief measure in S3 is as follows:

[0014] In low-stress areas, large-diameter boreholes are drilled directly. In high-stress areas, coal blasting holes are constructed first to loosen the coal and ensure that the effective impact of the pressure relief blasting covers the high-stress area. Then, large-diameter boreholes are drilled.

[0015] For additional large-diameter boreholes, the spacing should be 6-10m, the depth should be no less than 25m, and the diameter should be no less than 100mm. The borehole spacing should be 1-3m, depending on the risk level of rockburst. When the risk level of rockburst is weak, the borehole spacing should be 3m; when the risk level of rockburst is medium, the borehole spacing should be 2m; and when the risk level of rockburst is strong, the borehole spacing should be 1m.

[0016] The construction parameters for coal seam blasting holes are as follows: hole diameter 42-100mm, hole depth not less than 3 to 5 times the mining height, vertical to the roadway side, hole height 1.0m above the roadway floor; charge length not more than half the drilling depth, and sealing length not less than 1 / 3 of the hole depth.

[0017] Furthermore, the method for evaluating the pressure relief effect in the construction area during step S4 is as follows:

[0018] The pressure relief effect in high-stress roadways was verified using microseismic monitoring, stress monitoring, and drill cuttings monitoring. If the energy and frequency of events measured by microseismic monitoring decreased significantly compared to before pressure relief, the measured values ​​by stress monitoring were below the warning threshold, and the amount of coal dust per meter measured by drill cuttings monitoring decreased compared to before pressure relief with no stuck drill or drill bit suction phenomena, then the pressure relief effect was good. If the monitoring results did not decrease significantly, it indicated that the coal seam still had a risk of rockburst, and measures to increase the density of large-diameter boreholes were needed to reduce the risk of rockburst until the pressure relief effect met the set standards.

[0019] This invention first constructs large-diameter test boreholes in high-stress coal mine roadways. Based on the completion of these test boreholes, it identifies stress zones with varying levels of stress. For high-stress, drillable areas, a differentiated stress relief approach is adopted, employing blasting followed by drilling, while for low-stress, drillable areas, drilling is performed directly. This avoids the stress relief blind spots and resource waste inherent in traditional uniform borehole layouts. The test boreholes accurately determine the stress distribution, ensuring that the blasting loosening zone and the borehole stress relief zone effectively cover the high-stress area spatially, improving the targeting and borehole formation rate of stress relief operations. This invention achieves precise stress relief through a pre-exploration, post-treatment, and zoned approach, significantly reducing the risk of rockbursts in high-stress areas and enhancing the targeting, effectiveness, and economy of rockburst prevention. It has significant engineering practical value for rockburst prevention in coal mines. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the workflow of the method of the present invention;

[0021] Figure 2 This is a plan view of the differentiated stress relief method for high-stress areas of coal seams with test holes first, as described in this embodiment of the invention.

[0022] Figure 3 This is a cross-sectional view of the differentiated stress relief method for high-stress areas of coal seams with test holes first, as described in an embodiment of the present invention.

[0023] In the diagram: 1. Roadway, 2. Roadway sidewall, 3. Test hole, 4. Large-diameter borehole, 5. Coal blasting hole. Detailed Implementation

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a differentiated stress relief method for high-stress zones in coal mines, using a test hole-first approach, includes the following steps:

[0026] S1. Obtain mine geological survey data and geostress test data, and determine the construction area of ​​roadway in high-stress zone based on comprehensive index method, drill cuttings method and stress monitoring method;

[0027] S2. Large-diameter test holes 3 are arranged in the sidewall 2 of the roadway 1. The stress high and low zones are identified based on the completion status of the test holes 3.

[0028] S3. Take corresponding pressure relief measures for different stress zones;

[0029] S4. Evaluate the pressure relief effect in the construction area. If the pressure relief effect meets the set standard, the construction is completed; otherwise, increase the drilling density until the pressure relief effect meets the set standard.

[0030] Furthermore, the method for identifying high and low stress zones in S2 is as follows:

[0031] If test hole 3 reaches the designed depth, the area 3-5m before and after test hole 3 is determined to be a low-stress zone; if test hole 3 fails to reach the designed depth due to high stress during drilling, the area 3-5m before and after test hole 3 is determined to be a high-stress zone.

[0032] The test holes 3 are spaced 6-10m apart, with a hole depth of not less than 25m and a borehole diameter of not less than 100mm; the borehole inclination angle is adjusted on-site according to the coal seam dip angle to ensure that the borehole is located within the designed pressure relief zone.

[0033] Furthermore, the pressure relief measure in S3 is as follows:

[0034] In the low-stress zone, large-diameter borehole 4 is drilled directly. In the high-stress zone, coal blasting holes 5 are constructed first to loosen the coal body and ensure that the effective influence range of the pressure relief blasting covers the high-stress zone. Then, large-diameter borehole 4 is drilled.

[0035] For additional drilling, large-diameter boreholes should be drilled at intervals of 6-10m, with a depth of not less than 25m and a diameter of not less than 100mm. The borehole spacing should be 1-3m, determined according to the risk level of rock bursts. When the risk level of rock bursts is weak, the borehole spacing should be 3m; when the risk level of rock bursts is moderate, the borehole spacing should be 2m; and when the risk level of rock bursts is strong, the borehole spacing should be 1m.

[0036] The construction parameters for coal blasting hole 5 are as follows: hole diameter 42-100mm, hole depth not less than 3 to 5 times the mining height, vertical to the roadway side, hole height 1.0m above the roadway floor; charge length not more than half the drilling depth, and sealing length not less than 1 / 3 of the hole depth.

[0037] Furthermore, the method for evaluating the pressure relief effect in the construction area during step S4 is as follows:

[0038] The pressure relief effect in high-stress roadways was verified using microseismic monitoring, stress monitoring, and drill cuttings monitoring. If the energy and frequency of events measured by microseismic monitoring decreased significantly compared to before pressure relief, the measured values ​​by stress monitoring were below the warning threshold, and the amount of coal dust per meter measured by drill cuttings monitoring decreased compared to before pressure relief with no stuck drill or drill bit suction phenomena, then the pressure relief effect was good. If the monitoring results did not decrease significantly, it indicated that the coal seam still had a risk of rockburst, and measures to increase the density of large-diameter boreholes were needed to reduce the risk of rockburst until the pressure relief effect met the set standards.

[0039] Example: Figure 2As shown, taking the syncline axis region of the 1503 lower roadway in a certain mine as an example, due to the syncline structure, the 1503 lower roadway is in a high-stress state. Furthermore, during the deployment of large-diameter boreholes for stress relief, the drilling results varied significantly across different sections: some sections saw relatively smooth drilling, reaching the designed depth; while other sections experienced severe necking, borehole collapse, and drill bit jamming, resulting in insufficient borehole depth and failure to meet stress relief requirements. Based on the differentiated environment of the high-stress zone in this roadway, this invention is used for differentiated stress relief in the high-stress zone of the coal seam, with test holes preceding the actual operation. The specific implementation steps are as follows:

[0040] Step 1: Obtain mine geological survey data. Based on the comprehensive index method, drill cuttings method, stress monitoring method, etc., it was found that the stress was relatively high within 20m before and after the syncline of the 1503 working face. This area was classified as a high-stress zone. Differential stress relief of the coal seam high-stress zone was carried out in the test hole first in the high-stress zone of roadway 1.

[0041] Step 2: Drill large-diameter test holes

[0042] like Figure 2 As shown, starting from point H12 along the direction of roadway 1, large-diameter test boreholes 3 are arranged at 6m intervals on the roadway sidewall 2. The parameters for each test borehole are: diameter 133mm, designed depth 25m, height 1.5m, perpendicular to the roadway sidewall, and inclination angle 20°. Each borehole is constructed sequentially, and the completion status is recorded.

[0043] The construction results are as follows:

[0044] like Figure 3 As shown, the test holes that can be completed with large-diameter drilling are numbered as follows: 1#, 2#, 3#, 6#, and 7#.

[0045] The unfinished large-diameter test holes are numbered 4# and 5#.

[0046] Step 3: Divide the test areas into zones based on the completion status of adjacent test wells:

[0047] (1) Low stress drillable area: between 1# and 2#, between 2# and 3#, and between 6# and 7#, large diameter holes 4 are drilled. According to the impact risk assessment, the impact risk level is weak impact risk. The spacing between the holes is 3m, and the parameters are the same as the test hole parameters.

[0048] (2) High-stress, non-drillable areas: Supplementary blasting will be carried out between #3 and #4, #4 and #5, and #5 and #6. Supplementary coal blasting holes 5 will be drilled 6m apart on both sides of the uncompleted large-diameter test holes #4 and #5. The parameters for the blasting holes are: diameter 42mm, depth 13m, height 1m, and charge 4.5kg. After the blasting, large-diameter holes will be drilled between #3 and #4, #4 and #5, and #5 and #6, with a spacing of 3m and the same parameters as test hole 3.

[0049] Step 4: Validation of Results

[0050] The effectiveness of pressure relief in high-stress roadways was verified using microseismic monitoring, stress monitoring, and drill cuttings monitoring. Microseismic monitoring results showed that no microseismic events of magnitude 4 or higher occurred during subsequent mining operations after pressure relief, and the daily frequency of microseismic events decreased from 60 before pressure relief to 40. Drill cuttings monitoring results showed that the amount of coal dust extracted after pressure relief decreased from 2.85 kg / m³ before pressure relief to 2.44 kg / m³ (below the critical drill cuttings index of 2.8 kg / m³). Stress monitoring results showed that the stress value at shallow measuring points decreased from 11.5 MPa before pressure relief to 10.5 MPa (below the warning index of 11 MPa), and the stress value at deep measuring points decreased from 13.8 MPa before pressure relief to 12.2 MPa (below the warning index of 13 MPa). The verification showed that all warning indicators decreased compared to before pressure relief, indicating a good pressure relief effect and successful pressure relief.

Claims

1. A differentiated stress relief method for high-stress zones in coal mines, characterized by prior testing of test holes, wherein... Includes the following steps: S1. Obtain mine geological survey data and geostress test data, and determine the construction area of ​​roadway in high-stress zone based on comprehensive index method, drill cuttings method and stress monitoring method; S2. Large-diameter test holes are laid out in the sidewalls of the roadway, and stress high and low zones are identified based on the completion status of the test holes. S3. Take corresponding pressure relief measures for different stress zones; S4. Evaluate the pressure relief effect in the construction area. If the pressure relief effect meets the set standard, the construction is completed; otherwise, increase the drilling density until the pressure relief effect meets the set standard.

2. The differentiated stress relief method for high-stress zones in coal mines with test holes first, as described in claim 1, is characterized in that... The method for identifying high and low stress zones in S2 is as follows: If the test hole reaches the designed depth, the area within 3-5m before and after the test hole is determined to be a low-stress zone; if the test hole fails to reach the designed depth due to high stress during drilling, the area within 3-5m before and after the test hole is determined to be a high-stress zone. The test holes are spaced 6-10m apart, with a hole depth of not less than 25m and a borehole diameter of not less than 100mm. The borehole inclination angle is adjusted on-site according to the coal seam dip angle to ensure that the borehole is located within the designed pressure relief zone.

3. The differentiated stress relief method for high-stress zones in coal mines with test holes first, as described in claim 1, is characterized in that... The pressure relief measure in S3 is as follows: In low-stress areas, large-diameter boreholes are drilled directly. In high-stress areas, coal blasting holes are constructed first to loosen the coal and ensure that the effective impact of the pressure relief blasting covers the high-stress area. Then, large-diameter boreholes are drilled. For additional large-diameter boreholes, the spacing should be 6-10m, the depth should be no less than 25m, and the diameter should be no less than 100mm. The borehole spacing should be 1-3m, depending on the risk level of rockburst. When the risk level of rockburst is weak, the borehole spacing should be 3m; when the risk level of rockburst is medium, the borehole spacing should be 2m; and when the risk level of rockburst is strong, the borehole spacing should be 1m. The construction parameters for coal seam blasting holes are as follows: hole diameter 42-100mm, hole depth not less than 3 to 5 times the mining height, vertical to the roadway side, hole height 1.0m above the roadway floor; charge length not more than half the drilling depth, and sealing length not less than 1 / 3 of the hole depth.

4. The differentiated stress relief method for high-stress zones in coal mines with test holes first, as described in claim 1, is characterized in that... The method for evaluating the pressure relief effect in the construction area in S4 is as follows: The pressure relief effect in high-stress roadways was verified using microseismic monitoring, stress monitoring, and drill cuttings monitoring. If the energy and frequency of events measured by microseismic monitoring decreased significantly compared to before pressure relief, the measured values ​​by stress monitoring were below the warning threshold, and the amount of coal dust per meter measured by drill cuttings monitoring decreased compared to before pressure relief with no stuck drill or drill bit suction phenomena, then the pressure relief effect was good. If the monitoring results did not decrease significantly, it indicated that the coal seam still had a risk of rockburst, and measures to increase the density of large-diameter boreholes were needed to reduce the risk of rockburst until the pressure relief effect met the set standards.

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