A method for relieving pressure on isolated coal seams in a roadway with a floor rock.

Abstract

This invention discloses a method for relieving pressure on isolated coal bodies in a rock-bottomed roadway, belonging to the field of coal mine disaster prevention and control technology. The method includes obtaining basic parameters of the isolated coal body to be relieved; determining the number, horizontal position, and stratigraphic level of the rock-bottomed roadway for pressure relief based on the coal body width and floor conditions; determining a pressure relief scheme based on impact hazard assessment results and principal stress ratios, using large-diameter drilling, blasting, or a combination of both, and determining construction parameters; and drilling boreholes arranged in a fan-shaped or symmetrical fan-shaped pattern towards the coal body to be relieved within the rock-bottomed roadway, using a vertical line as a reference, to perform regional pressure relief. This invention transfers the pressure relief operation benchmark to the floor rock strata, avoiding the extremely high risk of personnel entering high-stress coal body areas for construction, mitigating the threat of water and gas disasters in goaf areas, effectively improving the correspondence between the pressure relief layout and the coal body condition, and ensuring safe mining.

Description

Technical Field

[0001] This invention relates to the field of coal mine disaster prevention and control technology, and in particular to a method for relieving pressure on isolated coal bodies in a bottom rock roadway. Background Technology

[0002] Coal is currently my country's primary energy source. During underground coal mining, rock bursts and coal and gas outbursts are serious dynamic hazards that threaten safe mine production. With increasing mining depth and more complex mining layouts, isolated coal seams surrounded by goaf areas often form underground. These isolated coal seams, due to the strong superposition of surrounding mining stresses, accumulate extremely high elastic energy, posing a very high risk of rock bursts.

[0003] To eliminate the impact hazard of isolated coal seams, existing technologies typically employ a series of pressure relief and anti-impact measures. Common approaches include directly excavating roadways within the coal seam, followed by measures such as coal seam drilling for pressure relief, coal seam pressure relief blasting, and coal seam water injection within the roadway; or using conventional methods such as deep-hole pre-fracturing blasting of the roof, hydraulic fracturing of the roof, and floor drilling for pressure relief and blasting to induce fracturing and decompression of the coal and rock mass.

[0004] However, the aforementioned conventional decompression strategies have significant limitations and safety hazards. Because isolated coal seams are in a state of high stress concentration, construction personnel and equipment directly entering the coal seam for tunnel excavation and decompression operations face extremely high risks of dynamic disasters. Furthermore, isolated coal seams typically have goafs above them. Directly fracturing the roof or implementing pre-decompression from within the coal seam can easily trigger a large influx of water or gas accumulated in the overlying goaf, resulting in extremely poor construction safety conditions and making it impossible to effectively guarantee the safe and efficient implementation of decompression projects.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for relieving pressure on isolated coal seams in a bottom rock roadway, in order to solve the technical defects of the prior art, which leads to high risk of dynamic disasters and extreme vulnerability to water and gas threats from the overlying goaf.

[0007] The technical solution of this invention is a method for relieving pressure on isolated coal seams using floor rock roadways. The method is used for isolated coal seams surrounded by goaf areas and posing a rockburst hazard. The method includes: obtaining basic parameters of the isolated coal seam to be relieved, including the width of the isolated coal seam, coal and gas outburst hazard, floor rock strata conditions, rockburst hazard assessment results, the ratio of maximum principal stress to self-weight stress, and coal body mechanical parameters; determining the number and horizontal position of floor rock roadways to be constructed or utilized based on the width of the isolated coal seam, and determining the stratum position of the floor rock roadways relative to the coal seam floor based on the coal and gas outburst hazard and floor rock strata conditions; and determining a pressure relief scheme based on the rockburst hazard assessment results and the ratio of maximum principal stress to self-weight stress, wherein... In the event of a shock hazard, large-diameter boreholes or blasting are used for pressure relief. In the event of a moderate to high shock hazard or when the ratio of the maximum principal stress to the self-weight stress reaches a preset triggering condition, a pressure relief scheme combining large-diameter boreholes and blasting is used. Based on the pressure relief scheme, the number, horizontal position, and stratum of the floor rock pressure relief roadway, and the mechanical parameters of the coal body, corresponding pressure relief construction parameters are determined. These pressure relief construction parameters include borehole pressure relief construction parameters, blasting pressure relief construction parameters, or combined pressure relief construction parameters. According to the pressure relief construction parameters, in the floor rock pressure relief roadway, with the vertical line passing through the midpoint of the roadway roof as a reference, pressure relief boreholes, blasting boreholes, or a combination of pressure relief boreholes and blasting boreholes arranged in a fan shape or symmetrical fan shape are constructed towards the isolated coal body to be pressured, so as to perform regional pressure relief on the isolated coal body to be pressured.

[0008] Optionally, the basic parameters are determined based on one or more of the following: mine geological data, mining engineering maps, field measurement data, mine pressure monitoring data, safety evaluation data, and coal and rock mechanics test data; wherein, the mine geological data, mining engineering maps, or field measurement data are used to determine the width of the isolated coal body to be unloaded and the conditions of the floor strata; the mine pressure monitoring data or safety evaluation data are used to determine the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress; and the coal and rock mechanics test data are used to determine the mechanical parameters of the coal body.

[0009] Optionally, determining the number and horizontal position of the floor rock stress relief roadways to be constructed or utilized based on the width of the isolated coal body to be unloaded includes: determining the width grading interval to which the width of the isolated coal body to be unloaded belongs; determining whether the floor rock stress relief roadways are arranged as a single roadway or multiple roadways according to the width grading interval; when the floor rock stress relief roadway is arranged as a single roadway, arranging it in the middle of the isolated coal body to be unloaded; when the floor rock stress relief roadway is arranged as multiple roadways, arranging multiple floor rock stress relief roadways at intervals along the width direction of the isolated coal body to be unloaded, and maintaining a safe edge distance between the outer floor rock stress relief roadway and the goaf boundary.

[0010] Optionally, determining the stratum position of the floor rock pressure relief roadway relative to the coal seam floor based on the coal and gas outburst hazard and the floor strata conditions includes: when the coal seam has no coal and gas outburst hazard, determining the vertical distance between the floor rock pressure relief roadway and the coal seam floor based on the floor strata conditions and the support conditions of the floor rock pressure relief roadway; when the coal seam has a coal and gas outburst hazard, arranging the floor rock pressure relief roadway in a stable stratum below the coal seam that meets the outburst prevention requirements.

[0011] Optionally, determining the pressure relief scheme based on the impact hazard assessment result and the ratio of the maximum principal stress to the self-weight stress includes: using the impact hazard assessment result as a hazard level criterion; using the ratio of the maximum principal stress to the self-weight stress as a stress concentration criterion; when neither the hazard level criterion nor the stress concentration criterion meets the combined pressure relief triggering condition, determining to adopt large-diameter drilling pressure relief or blasting pressure relief; when the hazard level criterion or the stress concentration criterion meets the combined pressure relief triggering condition, determining to adopt a pressure relief scheme combining large-diameter drilling pressure relief and blasting pressure relief.

[0012] Optionally, determining the corresponding pressure relief construction parameters based on the pressure relief scheme, the number, horizontal position, and stratigraphic position of the floor rock pressure relief roadway, and the coal body mechanical parameters includes: when the pressure relief scheme includes large-diameter borehole pressure relief, determining the coverage boundary of the pressure relief borehole in the width direction of the isolated coal body to be pressured, based on the width of the isolated coal body to be pressured, the goaf state, and the position of the floor rock pressure relief roadway; determining the arrangement range of the pressure relief borehole along the direction of the floor rock pressure relief roadway based on the length of the isolated coal body to be pressured and the pressure relief range of the pressure relief borehole; and determining the fan-shaped expansion range of the same group of pressure relief boreholes based on the coal body mechanical parameters and the coverage boundary.

[0013] Optionally, determining the corresponding pressure relief construction parameters based on the pressure relief scheme, the number, horizontal position, and stratigraphic position of the floor rock pressure relief roadway, and the coal body mechanical parameters further includes: when the pressure relief scheme includes blasting pressure relief, determining the final borehole boundary of the blasting borehole within the isolated coal body to be pressured based on the overlying strata state; determining the arrangement range of the blasting borehole along the direction of the floor rock pressure relief roadway based on the coal body mechanical parameters and the blasting disturbance range; and determining the interaction area between the blasting borehole and the isolated coal body to be pressured based on the final borehole boundary and the arrangement range.

[0014] Optionally, the combined pressure relief construction parameters include the drill-blast combination arrangement relationship set along the direction of the pressure relief tunnel of the bottom rock; the drill-blast combination arrangement relationship is: a set of blasting boreholes is set at every preset number of large-diameter pressure relief boreholes; the preset number of sets is determined according to the pressure relief range of the large-diameter pressure relief boreholes and the disturbance range of the blasting boreholes.

[0015] Optionally, the step of constructing, according to the pressure relief construction parameters, pressure relief boreholes, blasting boreholes, or combinations of pressure relief boreholes and blasting boreholes in a fan-shaped or symmetrical fan-shaped arrangement within the pressure relief roadway of the bottom rock, with the vertical line passing through the midpoint of the roadway roof as a reference, into the isolated coal body to be pressured, includes: using the pressure relief roadway of the bottom rock as the starting space for borehole construction; using the vertical line passing through the midpoint of the roadway roof as the reference for borehole arrangement; and, according to the pressure relief construction parameters, causing the pressure relief boreholes, blasting boreholes, or combinations of pressure relief boreholes and blasting boreholes to unfold in a fan-shaped or symmetrical fan-shaped arrangement into the interior of the isolated coal body to be pressured.

[0016] Optionally, during the process of regional depressurization of the isolated coal body to be depressurized, the method further includes: when the actual exposed goaf state, floor strata conditions, final borehole position, or borehole construction state is inconsistent with the construction boundary corresponding to the depressurization construction parameters, suspending the corresponding depressurization drilling or blasting drilling; adjusting the depressurization construction parameters according to the verified construction boundary; and supplementing the depressurization of the isolated coal body to be depressurized according to the adjusted depressurization construction parameters.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention, by acquiring the basic parameters of isolated coal seams and conducting impact hazard assessments, transfers the spatial benchmark for pressure relief construction to the pressure relief roadway in the floor rock beneath the coal seam, avoiding the risk of personnel and equipment being directly exposed to a high-stress hazardous environment. Based on the determined scheme and construction parameters, this invention constructs pressure relief boreholes or blasting boreholes in the floor rock pressure relief roadway in a fan-shaped or symmetrical fan-shaped pattern towards the coal seam to be pressured, using a vertical line as the benchmark. This not only achieves long-distance regional pressure relief in high-stress areas but also avoids goaf water hazards and gas outbursts caused by directly fracturing the roof. This control mechanism, which continuously connects roadway layout with multi-level pressure relief parameters, reduces the risk of impact prevention operations, improves the accuracy of matching pressure relief drilling and blasting layout with the spatial state of the coal seam, and ultimately ensures the safe and efficient mining of high-risk coal seams surrounded by goaf areas. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the planar structure of the isolated coal body to be unloaded and the surrounding goaf in an embodiment of the present invention;

[0020] in, Figure 1 Figure (a) is a plan view of an "isolated coal seam". Figure 1 Figure (b) is a cross-sectional view of the "isolated coal seam" AA. Figure 1 Figure (c) is a BB cross-section of an "isolated coal body";

[0021] Figure 2 This is a schematic diagram showing the arrangement and horizontal position of the rock unloading tunnels on the bottom plate of different width grade intervals in an embodiment of the present invention.

[0022] in, Figure 2 Figure (a) is a schematic plan of the layout of a decompression tunnel with a width of less than 100m for an "isolated coal body". Figure 2 Figure (b) is a schematic plan of the layout of a decompression tunnel for an "isolated coal seam" with a width greater than 100m and less than 200m. Figure 2 Figure (c) is a schematic diagram of the layout of a decompression tunnel with a width greater than 300m for an "isolated coal body";

[0023] Figure 3 This is a schematic diagram of the stratigraphic arrangement of the bottom rock pressure relief tunnel under different anti-outburst requirements in an embodiment of the present invention;

[0024] in, Figure 3 Figure (a) is a schematic diagram of the roadway strata layout when there is no risk of coal and gas outbursts. Figure 3 Figure (b) is a schematic diagram of the roadway strata layout when there is a risk of coal and gas outburst;

[0025] Figure 4 This is a schematic diagram of the fan-shaped arrangement of large-diameter pressure relief boreholes within an isolated coal seam to be pressure-relieved, as described in an embodiment of the present invention.

[0026] in, Figure 4 Figure (a) is a cross-sectional view of the borehole layout for pressure relief in an "isolated coal seam". Figure 4 Figure (b) is a schematic diagram of the layout of the pressure relief boreholes for the "isolated coal body" borehole;

[0027] Figure 5 This is a schematic diagram of the fan-shaped arrangement and final hole boundary of blasting boreholes under different overlying rock strata conditions in an embodiment of the present invention;

[0028] in, Figure 5 Figure (a) is a schematic diagram of the blasting borehole layout when the rock strata thickness between the isolated coal seam and the overlying goaf is greater than 5m. Figure 5 Figure (b) is a schematic diagram of the blasting borehole arrangement when the thickness of the rock strata between the isolated coal body and the goaf above is less than 5m. Figure 5 Figure (c) is a schematic diagram of the layout of the blasting and pressure relief boreholes for "isolated coal bodies";

[0029] Figure 6 This is a flowchart illustrating the implementation of a method for relieving pressure on isolated coal seams in a bottom rock roadway, as provided in an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] As mentioned earlier, rockbursts and coal and gas outbursts are key dynamic hazards that need to be prevented and controlled in coal mining. For isolated coal seams surrounded by goafs and posing a risk of rockburst, if the method of first excavating roadways within the coal seam and then implementing methods such as coal seam drilling for pressure relief, coal seam pressure relief blasting, coal seam water injection, deep hole pre-fracturing blasting of the roof, hydraulic fracturing of the roof, or drilling for pressure relief and blasting of the floor is still adopted, then the personnel and equipment for the pressure relief project need to enter a high-stress and dangerous environment. At the same time, when there is a goaf above the isolated coal seam and there may be constraints such as goaf water and gas, directly fracturing the roof or carrying out pre-pressure relief from inside the coal seam poses a high construction risk.

[0034] To address these issues, the present invention provides a method for relieving pressure on isolated coal seams in a bottom rock roadway, which solves the aforementioned problems in the following manner. The invention is further described below with reference to the accompanying drawings.

[0035] like Figures 1 to 6As shown in the embodiment of the present invention, the method for relieving pressure on isolated coal seams in a bottom rock roadway is applied to isolated coal seams that are surrounded by goaf areas and pose a risk of impact. This method can be implemented in conjunction with mine anti-rockfall design, mining and construction organization, and on-site safety inspection processes; the main focus can be control. The method mainly includes the following steps:

[0036] S100. Obtain the basic parameters of the isolated coal body to be unloaded. The basic parameters include the width of the isolated coal body to be unloaded, the coal and gas outburst hazard, the bottom strata conditions, the impact hazard assessment results, the ratio of the maximum principal stress to the self-weight stress, and the coal body mechanical parameters.

[0037] S200. Based on the width of the isolated coal body to be unloaded, determine the number and horizontal position of the bottom rock unloading roadway to be constructed or utilized, and based on the coal and gas outburst hazard and the bottom rock strata conditions, determine the stratum position of the bottom rock unloading roadway relative to the coal seam floor.

[0038] S300. Based on the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress, determine the pressure relief scheme. In the case of weak impact hazard, use large-diameter drilling or blasting pressure relief. In the case of medium or higher impact hazard or when the ratio of the maximum principal stress to the self-weight stress reaches the preset triggering condition, use a pressure relief scheme that combines large-diameter drilling and blasting pressure relief.

[0039] S400. Based on the pressure relief scheme, the number, horizontal position, and stratum of the pressure relief tunnels in the bottom rock, and the mechanical parameters of the coal body, determine the corresponding pressure relief construction parameters. The pressure relief construction parameters include drilling pressure relief construction parameters, blasting pressure relief construction parameters, or combined pressure relief construction parameters.

[0040] S500. According to the pressure relief construction parameters, in the pressure relief roadway of the bottom rock, with the vertical line passing through the midpoint of the roadway roof as the reference, pressure relief boreholes, blasting boreholes or combinations of pressure relief boreholes and blasting boreholes arranged in a fan shape or symmetrical fan shape are constructed towards the isolated coal body to be pressured, so as to perform regional pressure relief on the isolated coal body to be pressured.

[0041] Based on the above steps, this invention first determines the spatial reference of the bottom rock pressure relief roadway, then matches a single or combined pressure relief scheme according to the impact hazard assessment results and stress concentration criteria, and implements the pressure relief construction parameters into the fan-shaped or symmetrical fan-shaped borehole system constructed upward from the bottom rock pressure relief roadway. This eliminates the need for the pressure relief operation to be preconditioned by entering the interior of the isolated coal body to be pressured, thereby reducing the risk of directly entering the high-stress coal body area for pressure relief construction and improving the correspondence between the drilling pressure relief, blasting pressure relief, or combined pressure relief arrangement and the spatial state of the isolated coal body.

[0042] To provide a more detailed explanation of the technical solutions provided in the above embodiments, the present invention also provides another preferred embodiment.

[0043] In another embodiment of the present invention, obtaining the basic parameters of the isolated coal body to be unloaded in step S100 may include the following steps:

[0044] S110. The basic parameters are determined based on one or more of the following: mine geological data, mining engineering drawings, field measurement data, mine pressure observation data, safety evaluation data, and coal and rock mechanics test data.

[0045] In step S110, mine geological data, mining engineering maps, or field measurement data are used to determine the width, length, coal seam thickness, maximum burial depth, condition of goafs on both sides, condition of overlying goafs, and lithology of the roof and floor of the isolated coal body to be unloaded; mine pressure observation data or safety evaluation data are used to determine the impact hazard evaluation results and the ratio of maximum principal stress to self-weight stress; and coal rock mechanics test data are used to determine the mechanical parameters of the coal body.

[0046] For example, for Figure 1 For the isolated coal body awaiting depressurization shown, the mining area plan can be retrieved first to confirm the relative positions of the surrounding goaf, overlying goaf, adjacent main roadway, and floor strata. Then, the width, length, thickness, and depth of the coal body can be determined by combining on-site measurement data. Afterward, the impact hazard assessment data, mine pressure observation data, and coal rock mechanics test data can be compiled into a basic parameter package. This basic parameter package is then used in steps S200 and S300.

[0047] S120. The mine geological data, mining engineering drawings, or field measurement data are used to determine the width of the isolated coal body to be unloaded and the conditions of the bottom strata; the mine pressure observation data or safety evaluation data are used to determine the impact hazard evaluation results and the ratio of the maximum principal stress to the self-weight stress; the coal and rock mechanics test data are used to determine the mechanical parameters of the coal body.

[0048] In step S120, the width of the isolated coal body to be unloaded and the conditions of the bottom strata are determined in the process of determining the number, horizontal position and stratum of the bottom rock unloading roadway; the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress are determined in the process of determining the unloading scheme; and the mechanical parameters of the coal body are determined in the process of determining the drilling unloading construction parameters, blasting unloading construction parameters or combined unloading construction parameters.

[0049] For example, if the mining engineering drawings provide the boundary of an isolated coal seam to be unloaded, but field measurement data shows local deviations in the boundary, the width can be determined using the verified boundary. If the safety assessment data provides an assessment result of weak impact hazard or moderate to high impact hazard, then the assessment result shall be used as the hazard level criterion for step S300; if the coal and rock mechanics test data provides uniaxial compressive strength, uniaxial tensile strength, Poisson's ratio, internal friction angle or cohesion, then these mechanical parameters shall be used as the basis for parameter generation in step S400.

[0050] S130. Based on the basic parameters, form a parameter record for the isolated coal body to be unloaded, and confirm that the isolated coal body to be unloaded meets the applicable conditions of being surrounded by goaf areas and having a risk of impact.

[0051] In step S130, parameter recording is used to avoid repeated switching between different data calibers in subsequent steps. If the boundaries of the surrounding goaf, the state of the overlying goaf, the coal and gas outburst hazard, the floor strata conditions, or the impact hazard assessment results of the isolated coal body to be depressurized cannot be used to form records that can be used for construction design, then it is not advisable to directly proceed to the determination of depressurization construction parameters.

[0052] For example, when the mining engineering drawings show that there are goaf areas all around the isolated coal body to be unloaded, and the safety assessment data indicates that the coal body has a rockfall hazard, the coal body can be used as the object to be unloaded in this embodiment; if only some boundaries can be confirmed to have goaf areas, and other boundaries have not yet been identified, then data verification or supplementary exploration should be carried out first, and then proceed to step S200.

[0053] In another embodiment of the present invention, in step S200, determining the number and horizontal location of the floor rock decompression roadway based on the width of the isolated coal body to be decompressed, and determining the strata based on the coal and gas outburst hazard and floor strata conditions, may include the following steps:

[0054] S210. Determine the width grading interval to which the width of the isolated coal body to be unloaded belongs.

[0055] In step S210, the width grading interval is used to convert the width of the isolated coal body to be unloaded into the basis for selecting the number of floor rock unloading roadways. The width L can be determined by mine geological data, mining engineering drawings, or field measurement data.

[0056] For example, when the mining engineering drawings show the boundaries of the goaf areas on both sides of the isolated coal body to be unloaded, the width can be measured along the width direction of the coal body. The width is then assigned to the corresponding width grading interval; the judgment result proceeds to step S220 to determine whether a single lane or multiple lanes are arranged.

[0057] S220. Based on the width grading interval, determine whether the floor rock unloading roadway is arranged as a single roadway or multiple roadways; when the floor rock unloading roadway is arranged as a single roadway, arrange it in the middle of the isolated coal body to be unloaded; when the floor rock unloading roadway is arranged as multiple roadways, arrange multiple floor rock unloading roadways at intervals along the width direction of the isolated coal body to be unloaded, and maintain a safe edge distance between the floor rock unloading roadway located on the outer side and the boundary of the goaf.

[0058] In one specific embodiment of step S220, such as Figure 2 As shown, the width grading interval may include the following disclosed example intervals, and these example intervals are not intended as an exhaustive division of the entire range of coal body widths: when the width of an "isolated coal body" meets the following conditions... At that time, in the floor strata below the isolated coal body, a floor rock stress relief tunnel is arranged corresponding to the middle of the isolated coal body; when the width of the "isolated coal body" meets the requirements... At that time, two floor rock stress relief roadways were arranged in the floor strata below the isolated coal seam, with a roadway spacing of [missing information]. Furthermore, each roadway must be at least 50m away from the edge of the isolated coal seam; when the width of the "isolated coal seam" meets the following requirements... At that time, three bottom rock pressure relief tunnels were arranged in the bottom rock strata below the isolated coal body, and the three tunnels were distributed at equal intervals.

[0059] When the width of the isolated coal body to be unloaded does not fall within the above example range, the number and horizontal position of the bottom rock unloading roadway are determined according to the single-roadway or multi-roadway layout principle in step S220, combined with the coverage boundary of the unloading borehole, the safety edge distance, the existing position of the bottom rock unloading roadway, and the on-site construction boundary verification results.

[0060] For example, when the width of the isolated coal body to be unloaded... At this time, a single bottom rock relief roadway can be arranged below the middle of the coal seam in the width direction, so that subsequent boreholes can expand in a fan shape to both sides; when At that time, the spacing between the two bottom rock unloading tunnels can be determined according to... And maintain a distance of not less than [amount missing] from the edge of the isolated coal seam. The arrangement is such that the two lanes each cover an adjacent area; when In such cases, a three-lane, equally spaced arrangement can be adopted to create zonal coverage along the width direction for subsequent drilling or blasting holes. For isolated coal bodies awaiting decompression that do not fall within the width range of the examples above, the example values ​​are not directly applied. Instead, the single-lane or multi-lane arrangement is determined based on the verified coverage boundary, safety edge distance, and construction boundary.

[0061] S230. When there is no risk of coal and gas outburst in the coal seam, the vertical distance between the bottom rock strata and the coal seam floor shall be determined according to the bottom rock strata conditions and the support conditions of the bottom rock pressure relief roadway.

[0062] In one specific embodiment of step S230, such as Figure 3 As shown in Figure (a), when there is no risk of coal and gas outbursts in the coal seam, the floor rock relief roadway is arranged in the floor rock strata of the coal seam, and the distance between the roof of the floor rock relief roadway and the floor of the coal seam is not less than 2.0m of the length of the anchor bolts used, that is, the following relationship is satisfied:

[0063] (1)

[0064] in, The distance between the roof of the roadway and the floor of the coal seam when there is no coal or gas outburst risk, expressed in meters; The length of the anchor bolts for the roof support in the rock-relief tunnel floor is given in meters. The determination can be made based on the type of floor strata, the tunnel support design, or the results of on-site support calibration. In this embodiment, when the floor strata are claystone, When the base strata are clastic rocks, When the base strata are chemical and biochemical rocks, .

[0065] For example, when safety assessment data indicates that the coal seam poses no risk of coal and gas outbursts, and the floor strata are clastic rocks, the support design can be used to determine... , and according to The relationship determines the minimum vertical distance between the top plate of the rock pressure relief roadway and the bottom plate of the coal seam; this vertical distance is used in steps S410 to S450 to determine the borehole depth and final borehole boundary as the borehole enters the coal body from the roadway upwards.

[0066] S240. When the coal seam has the risk of coal and gas outburst, the bottom rock pressure relief roadway shall be arranged in a stable rock stratum below the coal seam that meets the requirements for outburst prevention.

[0067] In one specific embodiment of step S240, such as Figure 3 As shown in Figure (b), when a coal seam poses a risk of coal and gas outbursts, the floor rock relief roadway is located in the stable rock strata below the coal seam, and the distance between the roof of the floor rock relief roadway and the floor of the coal seam is not less than 5.0m, satisfying the following relationship:

[0068] (2)

[0069] in, This refers to the distance in meters (m) between the roof of a rock-relief roadway and the floor of a coal seam when the coal seam poses a risk of coal and gas outbursts. In specific engineering projects, the strata of the rock-relief roadway should be verified in conjunction with the mine's outburst prevention requirements, the stability of the floor strata, and the roadway support conditions.

[0070] For example, when the coal seam containing the isolated coal body to be unloaded is identified as having a coal and gas outburst risk, the floor rock unloading roadway is not directly located in the rock strata too close to the coal seam floor, but rather located in the stable rock strata below the coal seam, and... This stratum serves as the vertical reference for determining the subsequent borehole elevation angle, depth, and final borehole location.

[0071] In another embodiment of the present invention, in step S300, determining the pressure relief scheme based on the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress may include the following steps:

[0072] S310. The impact hazard assessment results shall be used as the hazard level criterion.

[0073] In step S310, the impact hazard assessment result can be determined from safety assessment data, mine pressure observation data, or existing impact prevention assessment conclusions. This assessment result is not used as the object of the new assessment model in this invention, but rather as the hazard level input for selecting the pressure relief path in this invention.

[0074] For example, if the comprehensive index method is used to evaluate that the isolated coal body to be depressurized has a weak impact hazard, the evaluation result will proceed to step S330 to select a single depressurization method; if the evaluation result is a medium or higher impact hazard, the evaluation result will proceed to step S340 to trigger a depressurization scheme that combines large-diameter borehole depressurization with blasting depressurization.

[0075] S320. The ratio of the maximum principal stress to the self-weight stress is used as the stress concentration criterion.

[0076] In step S320, the ratio of the maximum principal stress to the self-weight stress is used to characterize the stress concentration degree of the isolated coal body to be unloaded. This ratio can be derived from mine pressure observation data, stress analysis results, or pre-completed simulation calculations. As shown below:

[0077] (3)

[0078] in, The ratio of the maximum principal stress to the self-weight stress is used as the stress concentration criterion in step S330 or step S340. The maximum principal stress in the region corresponding to the isolated coal body to be unloaded can be determined from mine pressure observation data or the results of pre-completed stress analysis. The stress is due to its own weight and can be determined from the coal body's unit weight, burial depth, and existing mine pressure data.

[0079] For example, when simulation calculations or mine pressure analysis results indicate that the maximum principal stress of an isolated coal body reaches more than 5.0 times its own weight stress, that is... This state can be used as a stress concentration criterion to satisfy the combined stress relief triggering condition; if If the preset triggering conditions are not met, the decision on whether to adopt a single depressurization method will be made based on the impact hazard assessment results.

[0080] S330. When neither the hazard level criterion nor the stress concentration criterion meets the combined pressure relief triggering condition, it is determined that large-diameter drilling or blasting pressure relief shall be adopted.

[0081] In step S330, if the comprehensive index method is used to evaluate it as a weak impact hazard, and the ratio of the maximum principal stress to the self-weight stress does not reach the preset triggering condition, then one of the pressure relief techniques, namely large-diameter drilling of the coal body or coal body blasting pressure relief, can be adopted. Figure 6 The process shown uses a single pressure relief scheme for entering the borehole to relieve pressure in the case of weak impact hazard as an example.

[0082] For example, when an isolated coal seam awaiting depressurization is assessed as having a weak impact hazard, and If the 5.0 times trigger condition is not met, proceed to steps S410 to S430 to generate large-diameter borehole pressure relief construction parameters; if the engineering construction conditions, blasting safety regulations and approval conditions are met, proceed to steps S440 to S470 to generate blasting pressure relief construction parameters.

[0083] S340. When the hazard level criterion or the stress concentration criterion meets the combined pressure relief triggering condition, a pressure relief scheme combining large-diameter drilling pressure relief and blasting pressure relief is determined to be adopted.

[0084] In step S340, if the comprehensive index method is used to evaluate the coal body as having a medium to high impact risk, or if simulation calculations or mine pressure analysis are used to determine that the maximum principal stress of the isolated coal body to be unloaded is more than 5.0 times its own weight stress, then a pressure relief scheme combining large-diameter borehole pressure relief and coal body blasting pressure relief is adopted. The result of this path selection proceeds to step S480 to determine the N+1 combination layout.

[0085] For example, if the impact hazard assessment result is moderate to high impact hazard, even if the ratio of the maximum principal stress to the self-weight stress has not yet reached the trigger threshold individually, it can still enter the combined pressure relief path because the hazard level criterion meets the combined pressure relief triggering condition; if the impact hazard assessment result is not moderate to high, but... It also enters the combined depressurization path.

[0086] In another embodiment of the present invention, when the pressure relief scheme determined in step S300 includes large-diameter borehole pressure relief, step S400 may further include the following steps:

[0087] S410. When the pressure relief scheme includes large-diameter borehole pressure relief, the coverage boundary of the pressure relief borehole in the width direction of the isolated coal body to be pressured is determined according to the width of the isolated coal body to be pressured, the state of the goaf, and the location of the pressure relief roadway in the bottom rock.

[0088] In step S410, as Figure 4 As shown, large-diameter boreholes are arranged in the rock relief tunnel of the floor slab, with a borehole diameter of... The boreholes are arranged in a symmetrical fan shape, with the vertical line from the midpoint of the roof of the unloading rock tunnel as the axis of symmetry, and are constructed upwards to the isolated coal body.

[0089] For example, when the rock relief roadway is arranged in the middle of the isolated coal body to be relieved, the vertical line passing through the midpoint of the roadway roof can be used as the axis of symmetry to make the large-diameter boreholes in the same group spread to the left and right sides; when multiple rock relief roadways are arranged at intervals, each roadway forms a group of large-diameter boreholes in the corresponding coverage area.

[0090] S411. Determine the edge coverage boundary in the width direction based on the distance between the outermost borehole in each group of boreholes and the goaf on both sides.

[0091] (4)

[0092] Equation (4) above is used to determine the distance between the outermost borehole in each group of boreholes and the goaf on both sides, thereby defining the coverage boundary of the large-diameter borehole in the width direction of the isolated coal body to be unloaded. Where, The distance from the outermost borehole in each group of boreholes to the goaf on both sides, in meters. ; The influence coefficient of the width of the goaf on both sides of the isolated coal seam, when the goaf is in a fully mined state. When the goaf is in a state of incomplete mining. ; This refers to the bulk density of coal, in units of... It can be determined from mine geological data, coal and rock physical property data, or field calibration data; The maximum burial depth of an isolated coal seam, in meters, can be determined from mine geological data or mining engineering drawings; It represents the uniaxial compressive strength of an isolated coal body, expressed in MPa, and can be determined from coal and rock mechanics test data. The average thickness of an isolated coal seam, expressed in meters (m), can be determined from geological data, borehole columnar data, or field measurement data.

[0093] It should be noted that the relevant formulas involved in this manual are engineering empirical formulas. In specific calculations, you can directly substitute the values ​​of each physical quantity in the corresponding unit for calculation, or introduce the corresponding order of magnitude conversion factor to unify them into the standard unit system for calculation, so as to eliminate the difference in dimensions.

[0094] For example, when both sides of the isolated coal seam to be unloaded are in a fully mined state, the corresponding side can be taken. When one side of the goaf is in a state of incomplete mining, the corresponding side Calculated It is used to define the distance between the end position of the outermost borehole and the boundary of the goaf, and to enter the process of determining the number of boreholes in the same group, the spacing between boreholes in the group, and the fan-shaped expansion range.

[0095] S412. Determine the fan-shaped expansion range of the pressure relief boreholes in the same group based on the drilling depth, the number of boreholes in each group, and the spacing between boreholes within the group.

[0096] In step S412, the drilling depth is determined by penetrating the coal seam, and the final borehole location is at the top interface of the coal seam. The number of boreholes per group... Calculate and determine according to the following formula (5):

[0097] (5)

[0098] Intra-group borehole spacing The spacing at the end of the drilling is calculated according to formula (6):

[0099] (6)

[0100] In formulas (5) and (6), The width of the isolated coal seam to be unloaded is in meters and can be determined from mine geological data, mining engineering drawings, or on-site measurement data. The number of large-diameter pressure relief boreholes in each group; The distance between the final holes of the large-diameter pressure relief boreholes in the same group is in meters; the meanings of the other symbols are the same as in formula (4). Formula (5) outputs Formula (6) is used to determine the number of boreholes in the same group. Used to determine the lateral spacing at the end of the same group of boreholes, both are then used in step S500 for borehole construction layout.

[0101] For example, when both sides have been determined by formula (4) Then, the width L of the isolated coal body to be unloaded can be subtracted from the width corresponding to the distance between the two sides of the edge, and the number of boreholes in the same group can be determined according to formula (5). ; then with As the allocation benchmark, the spacing at the end of the boreholes in the same group is determined by formula (6). This allows the final borehole to form a coverable fan-shaped expansion range in the width direction of the coal body.

[0102] S413. Determine the layout range of the pressure relief boreholes along the direction of the pressure relief tunnel in the bottom rock based on the spacing and number of borehole groups.

[0103] In step S413, the spacing between borehole groups Determine according to formula (7):

[0104] (7)

[0105] In equation (7), The actual amount of pulverized coal discharged per unit length of a single borehole, expressed in kg, can be determined from on-site borehole discharge records or historical engineering statistics. The density of an isolated coal body is expressed in kg / m³ and can be determined from coal and rock physical property data or coal and rock mechanical test data. The borehole diameter is measured in meters and can be determined by the construction design, the capacity of the drilling equipment, or the on-site operating procedures. It represents the cohesion within an isolated coal seam, measured in MPa, and can be determined from coal and rock mechanics test data. The friction angle within an isolated coal seam, expressed in degrees, can be determined from coal and rock mechanics test data; , and The meaning is the same as before. The calculation result of formula (7) Used to determine the spacing between adjacent borehole groups along the direction of the rock pressure relief tunnel in the floor.

[0106] In step S413, the distance from the end point of the first and last groups of large-diameter pressure relief boreholes to the edge of the "isolated coal body" is not less than 5m. Therefore, the number of pressure relief borehole groups is... Calculate according to formula (8):

[0107] (8)

[0108] In equation (8), Number of large-diameter pressure relief borehole groups; The length of an isolated coal seam is measured in meters and can be determined from mining engineering drawings, geological data, or on-site measurement data. The spacing between borehole groups is determined by formula (7). The calculation result of formula (8) is used to determine the number of large-diameter pressure relief borehole groups that need to be arranged along the roadway direction, and then proceeds to the construction organization in step S500.

[0109] For example, when the length of an isolated coal seam... It has been determined by the mining engineering drawings and obtained by formula (7). When, it can be calculated according to formula (8). And ensure that the distance between the end of the first and last pressure relief boreholes is not less than 5m from the edge of the isolated coal body; if the calculation results in insufficient distance between the first and last groups, return to step S413 to check the group spacing or number of groups.

[0110] In another embodiment of the present invention, when the depressurization scheme determined in step S300 includes explosive depressurization, step S400 may further include the following steps:

[0111] S440. When the pressure relief scheme includes blasting pressure relief, the final hole boundary of the blasting borehole in the isolated coal body to be relieved is determined according to the state of the overlying strata of the isolated coal body to be relieved.

[0112] In step S440, as Figure 5 As shown, blasting boreholes are arranged in the rock relief tunnel of the floor slab, and the borehole diameter meets the following requirements. The boreholes within the group are arranged symmetrically in a fan shape, with the vertical line from the midpoint of the roof of the pressure relief tunnel as the axis of symmetry, and are constructed upwards to the isolated coal seam. Blasting pressure relief operations should be carried out under the premise of meeting the mine blasting safety regulations and on-site construction safety conditions.

[0113] For example, after the strata of the bottom rock pressure relief roadway have been determined according to step S200, blasting boreholes can be arranged upwards from inside the roadway; the same group of blasting boreholes are arranged in a fan shape with the vertical line passing through the midpoint of the roadway roof as the axis of symmetry, so that the area of ​​blasting disturbance corresponds to the internal area of ​​the isolated coal body to be pressured.

[0114] S441. Determine the edge boundary of the blasting area based on the distance between the outermost borehole in each group of blasting boreholes and the goaf on both sides.

[0115] As shown below:

[0116] (9)

[0117] Formula (9) is used to determine the distance between the outermost borehole in each group of blasting boreholes and the goaf on both sides. Where, The distance from the outermost borehole in each group of blasting boreholes to the goaf on both sides, in meters. ; , , , and The meaning of is the same as that of formula (4), and the source of the parameters is also the same as that of formula (4). The calculation result of formula (9) is used to limit the final edge of the blasting borehole in the width direction, so as to avoid the blasting borehole action area being too close to the boundary of the goaf.

[0118] For example, in cases where the goaf is under fully mined and under partially mined conditions, the corresponding values ​​can be taken respectively. And determine the two sides according to formula (9) The results are then used to determine the number of blasting boreholes, the spacing between groups, and the final borehole layout range.

[0119] S442. Determine the blasting borehole depth based on the condition of the overlying goaf or the thickness of the rock strata between the coal body and the overlying goaf.

[0120] In step S442, when the thickness of the rock strata between the isolated coal body and the goaf above is greater than 5m, or when there is no goaf overlying the isolated coal body, the hole depth is based on penetrating the coal body, and the final hole position is located at the top interface of the coal seam; when the thickness of the rock strata between the isolated coal body and the goaf above is less than 5m, the distance from the final hole point to the top of the coal seam is not less than 5m.

[0121] For example, such as Figure 5 As shown in Figure (a), when the stratum thickness between an isolated coal seam and the overlying goaf is greater than 5m, the blasting borehole can be aimed at penetrating the coal seam, with the final borehole location at the top interface of the coal seam; as Figure 5 As shown in Figure (b), the stratum thickness between the isolated coal seam and the overlying goaf is less than In this case, the final drilling point of the blasting borehole does not directly reach the roof of the coal seam, but maintains a distance of not less than [missing information]. Safe distance.

[0122] S443. Determine the fan-shaped expansion range of the blasting boreholes based on the number of blasting boreholes in each group and the spacing between blasting boreholes within the group.

[0123] Number of blasting boreholes per group Calculated according to formula (10):

[0124] (10)

[0125] In equation (10), The number of blasting holes per group; The radius of the blasting hole is in meters. ; The detonation velocity of the explosive is expressed in m / s and can be determined from the selected mining explosives data or blasting procedures. The Poisson's ratio for an isolated coal body can be determined from coal and rock mechanics test data; The density of the explosive is expressed in kg / m³ and can be determined from the explosive manufacturer's data or blasting regulations. This refers to the tensile strength of an isolated coal seam, expressed in MPa, and can be determined from coal and rock mechanics test data. , , , , and The meaning is the same as before. The calculation result of formula (10) is used to determine the number of blasting boreholes in the same group.

[0126] The spacing d2 between blasting boreholes within the group is the spacing at the end of the blasting boreholes, calculated according to formula (11):

[0127] (11)

[0128] In the formula, The distance between the final holes of the blasting boreholes within the group, in meters; The number of blasting boreholes in each group is calculated using formula (10); the meanings of the other symbols are the same as before. The output of formula (11) is used to determine the lateral distribution at the end of the blasting boreholes in the same group and to proceed to the blasting borehole construction in step S500.

[0129] For example, after determining both sides Then, the width of the isolated coal body can be used. After deducting the width corresponding to the distance between the two blasting edges, the result is determined by formula (10). Then, use formula (11) to determine This causes the final positions of the blasting boreholes in the same group to spread out in a fan shape within the workable boundary.

[0130] S444. Determine the charge length per hole based on the coal's mechanical parameters and blasting parameters.

[0131] In step S444, the charge amount per orifice is characterized by the charge length Lc and determined according to formula (12):

[0132] (12)

[0133] In the formula, This refers to the length of the single-hole charge. This is the blasting energy loss coefficient, generally 0.1-0.2, and 0.15 for coal bodies; The factor representing the increase in uniaxial compressive strength of an isolated coal seam is taken as... ; It represents the uniaxial compressive strength of an isolated coal body, expressed in MPa, and can be determined from coal and rock mechanics test data. The stress amplification factor generated by the explosive gas. 12 were taken from the coal body; The density of the explosive is expressed in kg / m³ and can be determined from the explosive manufacturer's data or blasting regulations. The detonation velocity of the explosive is expressed in m / s and can be determined from the explosive manufacturer's data or blasting regulations. This is the attenuation index of the blast shock wave in the fracture zone, which is generally taken as 3; The diameter of the explosive cartridge is in mm and can be determined from the cartridge specification data. The diameter of the blast hole is in mm and can be determined by the blast hole construction specifications. The calculation result of formula (12) is used in the single-hole charging design and should be subject to the mine blasting safety regulations, on-site approval and construction safety conditions.

[0134] For example, when the diameter of the blast hole... , diameter of the medicine roll Explosive detonation velocity and explosive density The uniaxial compressive strength of the coal seam has been determined by the blasting design or manufacturer's data. When the length of the charge in a single hole has been determined by coal and rock mechanics test data, it can be calculated using formula (12). ;Should It is not used as a fixed universal value, but rather for the design of charge parameters for the current isolated coal body to be unloaded and the current blasting construction conditions.

[0135] S445. Determine the layout range of blasting boreholes along the direction of the rock pressure relief tunnel in the floor slab based on the spacing of the blasting boreholes and the number of blasting borehole groups.

[0136] In step S445, the spacing of the blasting boreholes Determine according to formula (13):

[0137] (13)

[0138] In the formula, The spacing of the blasting boreholes along the direction of the rock pressure relief tunnel in the floor slab; The disturbance influence coefficient for a single set of internal blast holes is generally taken as 0.2-1.0, and 0.5 for the coal body. The number of blasting boreholes per group is determined by formula (10); , , , , , and The meaning is the same as before. The calculation result of formula (13) is used to determine the arrangement spacing of adjacent blasting borehole groups along the roadway direction.

[0139] In step S445, the distance from the end point of the first and last groups of blasting pressure relief boreholes to the edge of the "isolated coal body" is not less than 10m. Therefore, the number of blasting borehole groups N2 is calculated according to formula (14):

[0140] (14)

[0141] In equation (14), Number of blasting and pressure relief borehole groups; The length of an isolated coal seam is measured in meters and can be determined from mining engineering drawings, geological data, or on-site measurement data. The spacing of the blasting boreholes is determined by formula (13). The calculation result of formula (14) is used to determine the number of blasting borehole groups that need to be arranged along the direction of the rock pressure relief tunnel in the bottom plate, and then proceeds to the blasting construction organization in step S500.

[0142] For example, when , Once determined, it can be determined using formula (14). And ensure that the distance between the end of the first and last blasting decompression boreholes and the edge of the isolated coal body is not less than 10m; if the calculation result does not meet the edge distance requirement, return to step S445 to adjust the spacing or number of blasting boreholes.

[0143] In another embodiment of the present invention, when step S300 determines that a pressure relief scheme combining large-diameter drilling and explosive pressure relief is adopted, step S400 further includes the following steps:

[0144] S480, the combined pressure relief construction parameters include the drill-blast combination arrangement relationship set along the direction of the pressure relief tunnel of the bottom rock; the drill-blast combination arrangement relationship is: a set of blasting boreholes is set at every preset number of large-diameter pressure relief boreholes; the preset number of sets is determined according to the pressure relief range of the large-diameter pressure relief boreholes and the disturbance range of the blasting boreholes.

[0145] In step S480, if the isolated coal body is evaluated as having a medium or higher impact hazard using the comprehensive index method, or if the maximum principal stress of the isolated coal body is found to be more than 5.0 times its own weight stress using simulation calculation, then a scheme combining large-diameter borehole decompression and coal body blasting decompression is adopted, arranged according to N+1, that is, after N sets of large-diameter boreholes, 1 set of blasting holes is arranged, where N is calculated according to formula (15):

[0146] (15)

[0147] In equation (15), The preset number of groups to arrange one blasting borehole after a certain number of large-diameter pressure relief boreholes in the combined pressure relief scheme; The spacing of the large-diameter pressure relief borehole group is determined by formula (7); The spacing of the blasting boreholes is determined by formula (13). Formula (15) outputs... This is used to correlate the borehole pressure relief range with the blasting disturbance range along the direction of the pressure relief tunnel in the bottom rock, so that the combined pressure relief construction parameters can be converted into the drilling and blasting sequence in the on-site construction drawings or construction organization design.

[0148] For example, when step S413 calculates the spacing of the large-diameter pressure relief borehole group... Step S445 calculates the spacing of the blasting boreholes. Then, it can be determined according to formula (15). Subsequently, the following was arranged along the direction of the rock relief tunnel in the bottom plate: A set of large-diameter pressure relief boreholes is arranged, followed by a set of blasting boreholes, and the combined pressure relief construction sections are determined cyclically according to this arrangement.

[0149] In another embodiment of the present invention, step S500, implementing regional depressurization in the bottom rock depressurization tunnel according to the depressurization construction parameters, may include the following steps:

[0150] S510, The bottom rock pressure relief tunnel is used as the starting space for drilling construction.

[0151] In step S510, the floor rock pressure relief roadway can be a newly constructed rock roadway in the floor rock strata below the isolated coal body, or it can be an existing floor gas drainage roadway located in the floor rock. After using this roadway as the starting space for construction, pressure relief boreholes, blasting boreholes, or a combination of both are constructed from the floor rock pressure relief roadway upwards to the isolated coal body to be pressured.

[0152] For example, when there is an existing gas drainage tunnel on the ground and its location, stratum, and support conditions meet the requirements of step S200, the existing tunnel can be used as a rock pressure relief tunnel for the ground. When there is no usable tunnel on the ground, a rock pressure relief tunnel for the ground can be constructed according to the quantity, horizontal position, and stratum determined in step S200.

[0153] S520. The vertical line passing through the midpoint of the tunnel roof is used as the reference for borehole layout.

[0154] In step S520, a perpendicular line passing through the midpoint of the roadway roof is used to establish a symmetrical arrangement reference for boreholes or blasting holes. For large-diameter pressure relief boreholes, this perpendicular line serves as the central axis of symmetrical fan-shaped boreholes; for blasting boreholes, this perpendicular line serves as the central axis of the symmetrical fan-shaped arrangement within the group.

[0155] For example, when constructing in a rock-relief tunnel, the midpoint of the roof can be determined in the tunnel cross-section first, and then a vertical line can be drawn along the midpoint of the roof. Subsequently, the same set of relief boreholes or blasting boreholes can be expanded on both sides of the vertical line as the axis of symmetry.

[0156] S530. According to the pressure relief construction parameters, the pressure relief borehole, blasting borehole, or combination of pressure relief borehole and blasting borehole is made to expand into the isolated coal body to be pressured in a fan shape or symmetrical fan shape.

[0157] In step S530, if the pressure relief scheme is large-diameter borehole pressure relief, then according to , , , , and Construction of pressure relief drilling with equal parameters; if the pressure relief scheme is blasting pressure relief, then according to... , , , , , and The parameters are equal for blasting drilling and charging; if the pressure relief scheme is a combined pressure relief, the large-diameter pressure relief drilling and blasting drilling are organized according to the N+1 drilling and blasting combination arrangement.

[0158] For example, in cases of minor impact risk, one can follow... Figure 4 The borehole decompression arrangement shown involves constructing large-diameter decompression boreholes upwards from the bottom rock decompression tunnel; in areas with moderate to high impact hazard or In this case, it can be done according to Figure 4 and Figure 5 The arrangement shown combines with formula (15) to form a combined layout, that is, after completing N sets of large-diameter pressure relief boreholes, 1 set of blasting boreholes is arranged.

[0159] S540, according to Figure 6 The process shown organizes depressurization in the bottom rock tunnel area.

[0160] In step S540, the basic parameters of the isolated coal body are first determined; then, based on the basic parameters, the shape-related parameters of the isolated coal body are further clarified, specifically including the coal body length, width, coal seam thickness, burial depth, the state of the goaf on both sides, and the lithology of the roof and floor; after completing the collection and determination of the coal body parameters, the layout parameters of the floor rock stress relief roadway are determined, namely the number and strata of the roadways; then, the impact hazard assessment of the isolated coal body is carried out, and the ratio of the maximum principal stress to the vertical stress of the isolated coal body is obtained through simulation calculation to complete the impact hazard level determination; based on the impact hazard level, a formula is developed. The pressure relief scheme is as follows: if the risk of weak impact is determined, a single pressure relief scheme of borehole pressure relief is adopted; if the risk of moderate or greater impact is determined, a combined pressure relief scheme of borehole pressure relief and blasting pressure relief is adopted. After determining the pressure relief scheme, the mechanical parameters of the coal body are simultaneously determined, including the uniaxial compressive strength, uniaxial tensile strength, Poisson's ratio, internal friction angle, and cohesion of the coal body. Finally, based on the selected pressure relief scheme and the mechanical parameters of the coal body, the pressure relief parameters involved in the pressure relief scheme are calculated and determined, namely, borehole depth, number of boreholes in each group, borehole spacing, number of borehole groups, and charging parameters.

[0161] For example, according to Figure 6When the process is executed, if the basic parameters show that the width of the isolated coal body is suitable for arranging a bottom rock pressure relief roadway, and the impact hazard assessment result is a weak impact hazard, then the roadway strata, coal body mechanical parameters and borehole pressure relief parameters can be determined in sequence, and a large-diameter pressure relief borehole can be constructed in the bottom rock pressure relief roadway; if the assessment result is a medium or higher impact hazard, then the blasting pressure relief parameters can be determined at the same time as the borehole pressure relief parameters, and the combined pressure relief can be organized according to the N+1 relationship.

[0162] S550. When the actual revealed goaf condition, floor strata condition, final borehole location, or borehole construction status is inconsistent with the construction boundary corresponding to the pressure relief construction parameters, the corresponding pressure relief drilling or blasting drilling shall be suspended; the pressure relief construction parameters shall be adjusted according to the verified construction boundary; and the isolated coal body to be pressured shall be supplemented with pressure relief according to the adjusted pressure relief construction parameters.

[0163] In step S550, the construction boundary verification is used to handle situations where the information revealed on site is inconsistent with the previous design parameters. If situations such as goaf water hazards, abnormal gas, dynamic manifestations, changes in the bottom rock strata conditions, deviation of the final borehole position, or lack of safety basis for charging parameters occur during construction, the corresponding construction branch should be stopped, and the process should return to step S400 to verify the borehole depth, number of groups, spacing, charging length, or N+1 arrangement relationship.

[0164] For example, if the actual final borehole location deviates from the top coal seam interface during drilling, or if the actual exposed overlying goaf is inconsistent with the original construction boundary, the drilling of that borehole group should be suspended and the final borehole boundary should be checked. If, after the check, the local area is not covered by drilling or blasting, pressure relief boreholes should be added or the layout of local blasting boreholes should be adjusted according to the adjusted parameters.

[0165] Accordingly, this invention continuously connects the process of determining the number, horizontal position, and stratigraphic level of the bottom rock stress relief roadway with the impact hazard level, stress concentration ratio, borehole stress relief parameters, blasting stress relief parameters, and N+1 combination arrangement relationship, so that the drilling or blasting construction in the bottom rock roadway can be organized and implemented according to the spatial state and hazard state of the isolated coal body to be stressed, thereby providing executable construction parameters and construction sequence for the regional stress relief of the isolated coal body in the surrounding goaf.

[0166] The above description is merely a preferred embodiment of the technical solution of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for relieving pressure on isolated coal seams in a roadway with a floor rock, characterized in that, The method is used for isolated coal seams surrounded by goaf areas and posing a risk of impact, including: Obtain the basic parameters of the isolated coal body to be unloaded, including the width of the isolated coal body to be unloaded, the risk of coal and gas outburst, the conditions of the bottom strata, the impact hazard assessment results, the ratio of the maximum principal stress to the self-weight stress, and the mechanical parameters of the coal body; Based on the width of the isolated coal seam to be unloaded, determine the number and horizontal location of the floor rock unloading roadways to be constructed or utilized, and based on the coal and gas outburst hazard and floor strata conditions, determine the stratum position of the floor rock unloading roadways relative to the coal seam floor, including: Determine the width grading range to which the width of the isolated coal body to be unloaded belongs; Based on the width grading range, the bottom rock unloading tunnel is determined to be either a single tunnel or a multi-tunnel arrangement; When the bottom rock unloading roadway is arranged as a single roadway, the bottom rock unloading roadway is arranged in the middle of the isolated coal body to be unloaded; When the bottom rock pressure relief roadway is arranged in a multi-roadway configuration, the multiple bottom rock pressure relief roadways are arranged at intervals along the width direction of the isolated coal body to be pressured, and a safe edge distance is maintained between the bottom rock pressure relief roadway located on the outer side and the boundary of the goaf. It also includes: when there is no risk of coal and gas outburst in the coal seam, determining the vertical distance between the bottom rock strata and the coal seam floor based on the bottom rock strata conditions and the support conditions of the bottom rock stress relief roadway; When a coal seam poses a risk of coal and gas outburst, the bottom rock pressure relief roadway is arranged in a stable rock stratum below the coal seam that meets the requirements for outburst prevention. Based on the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress, a pressure relief scheme is determined. Specifically, for weak impact hazards, large-diameter drilling or blasting pressure relief is used. For moderate to high impact hazards, or when the ratio of the maximum principal stress to the self-weight stress reaches a preset triggering condition, a pressure relief scheme combining large-diameter drilling and blasting pressure relief is used, which includes: The impact hazard assessment results will be used as the criterion for hazard level determination. The ratio of the maximum principal stress to the self-weight stress is used as the stress concentration criterion. When neither the hazard level criterion nor the stress concentration criterion meets the combined pressure relief triggering condition, it is determined that large-diameter drilling or blasting pressure relief shall be adopted. When the hazard level criterion or the stress concentration criterion meets the combined pressure relief triggering condition, a pressure relief scheme combining large-diameter drilling pressure relief and blasting pressure relief is determined to be adopted. Based on the pressure relief scheme, the number, horizontal position, and stratigraphic level of the floor rock pressure relief tunnels, and the mechanical parameters of the coal seam, corresponding pressure relief construction parameters are determined. These pressure relief construction parameters include drilling pressure relief construction parameters, blasting pressure relief construction parameters, or a combination of pressure relief construction parameters, which include: When the pressure relief scheme includes large-diameter borehole pressure relief, the coverage boundary of the pressure relief borehole in the width direction of the isolated coal body to be pressured is determined according to the width of the isolated coal body to be pressured, the state of the goaf, and the location of the pressure relief roadway in the bottom rock. Based on the length of the isolated coal body to be unloaded and the unloading range of the unloading boreholes, determine the arrangement range of the unloading boreholes along the direction of the unloading roadway in the bottom rock. Based on the coal body mechanical parameters and the cover boundary, determine the fan-shaped expansion range of the pressure relief boreholes in the same group; When the pressure relief scheme includes blasting pressure relief, the final hole boundary of the blasting borehole in the isolated coal body to be relieved is determined according to the state of the overlying strata of the isolated coal body to be relieved. Based on the aforementioned coal mechanical parameters and the range of blasting disturbance, determine the arrangement range of blasting boreholes along the direction of the rock pressure relief roadway in the floor slab; The interaction area between the blasting borehole and the isolated coal body to be unloaded is determined based on the final borehole boundary and the arrangement range. According to the pressure relief construction parameters, in the pressure relief roadway of the bottom rock, with the vertical line passing through the midpoint of the roadway roof as the reference, pressure relief boreholes, blasting boreholes or combinations of pressure relief boreholes and blasting boreholes arranged in a fan shape or symmetrical fan shape are constructed towards the isolated coal body to be pressured, so as to perform regional pressure relief on the isolated coal body to be pressured.

2. The method for relieving pressure on isolated coal seams in a bottom rock roadway according to claim 1, characterized in that, The basic parameters are determined based on one or more of the following: mine geological data, mining engineering maps, field measurement data, mine pressure observation data, safety evaluation data, and coal and rock mechanics test data. The mine geological data, mining engineering drawings or field measurement data are used to determine the width of the isolated coal body to be unloaded and the conditions of the bottom strata. The mine pressure observation data or safety assessment data are used to determine the impact hazard assessment results and the ratio of the maximum principal stress to the self-weight stress; The coal and rock mechanics test data are used to determine the mechanical parameters of the coal body.

3. The method for relieving pressure on isolated coal seams in a bottom rock roadway according to claim 1, characterized in that, The combined pressure relief construction parameters include the drilling and blasting combination arrangement relationship set along the direction of the pressure relief tunnel of the bottom rock; The arrangement of the drilling and blasting combination is as follows: a set of blasting boreholes is set up for every preset number of large-diameter pressure relief boreholes; The preset number of groups is determined based on the pressure relief range of the large-diameter pressure relief borehole and the disturbance range of the blasting borehole.

4. The method for relieving pressure on isolated coal seams in a bottom rock roadway according to claim 1, characterized in that, The construction of pressure relief boreholes, blasting boreholes, or a combination of pressure relief boreholes and blasting boreholes arranged in a fan shape or symmetrical fan shape is carried out in the pressure relief roadway of the bottom rock, with the vertical line passing through the midpoint of the roadway roof as the reference, towards the isolated coal body to be pressured, according to the pressure relief construction parameters. The rock pressure relief tunnel at the bottom plate is used as the starting space for drilling construction; The vertical line passing through the midpoint of the tunnel roof is used as the reference for borehole layout. According to the pressure relief construction parameters, the pressure relief borehole, blasting borehole, or combination of pressure relief borehole and blasting borehole are made to expand into the isolated coal body to be pressured in a fan shape or symmetrical fan shape.

5. The method for relieving pressure on isolated coal seams in a bottom rock roadway according to claim 1, characterized in that, In the process of regionally depressurizing the isolated coal seam to be depressurized, the method further includes: When the actual revealed goaf state, floor strata conditions, final borehole location, or borehole construction state is inconsistent with the construction boundary corresponding to the pressure relief construction parameters, the corresponding pressure relief drilling or blasting drilling shall be suspended. The pressure relief construction parameters are adjusted based on the verified construction boundaries. According to the adjusted depressurization construction parameters, the isolated coal body to be depressurized is further depressurized.

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