A method for determining the energy accumulation layer of the overlying strata

Abstract

A method for determining the energy accumulation layer of overlying strata includes the following steps: determining a suitable blasting location based on geological conditions and working face mining conditions; determining deep-hole blasting construction parameters based on rock strata properties and drilling equipment conditions; dividing several rock strata with similar lithology into a group based on the borehole columnar section drawn after core sampling and analysis, using this group as a blasting target, and determining its stratigraphic position; blasting the overlying rock strata group by adjusting the position and length of the charging section and plugging section; recording and collecting the waveform signals generated by the blasting using a microseismic monitoring system and calculating the energy; comparing the calculated energy and determining the rock strata group with the highest energy as the energy accumulation layer. This method enables a systematic study of energy accumulation layers from the perspective of energy calculation, providing a theoretical research basis and operational guidance for safe mine production.

Description

Technical Field

[0001] This invention relates to a method for determining the energy accumulation layer of overlying strata, belonging to the field of coal mine safety mining technology. Background Technology

[0002] Above the coal seam lie multiple layers of rock of varying thickness and strength. One or more of these layers may accumulate a large amount of energy. Once these layers fracture, their internal elastic energy will be suddenly released, causing a significant increase in stress in the underlying coal and rock mass. This, in turn, leads to the instability and failure of the coal and rock mass system, which is already under extreme stress. The superposition of this energy with the already high static load on the roadway can trigger a large-scale rockburst, seriously affecting the safe production operations of the mine.

[0003] Therefore, the rapid and accurate identification of the location of overlying energy accumulation layers is of great significance for safe mining. After determining the location of the energy accumulation layer, pressure relief treatments such as blasting and water injection can be carried out before mining to control the energy release caused by the fracture of the energy accumulation layer, thereby avoiding the impact of mine tremors on production. However, existing research and identification methods for key overlying layers have not systematically studied energy accumulation layers from the perspective of energy solution. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for determining the energy accumulation layer of the overlying strata. This method determines the location of the energy accumulation layer of the overlying strata, enabling subsequent fracturing control, and allows for a systematic study of the energy accumulation layer from the perspective of energy solution. This fills a gap in the field and provides a theoretical research basis and operational guidance for safe production in mines.

[0005] To achieve the above objectives, the present invention provides a method for determining an overlying energy accumulation layer, comprising the following steps:

[0006] (1) Determine the appropriate blasting location based on geological conditions and mining conditions at the working face;

[0007] (2) Determine the deep hole blasting construction parameters based on the rock strata properties and drilling equipment conditions. The construction parameters include the blasting hole diameter, blasting hole depth, blasting hole inclination angle, charge amount and sealing length.

[0008] (3) Based on the borehole columnar section drawn after sampling and analysis of the borehole core, several layers of rock with similar lithology in the overlying rock of the coal seam are divided into a rock layer group as a group of blasting targets, and the distance of the rock layer group from the coal seam is determined; the overlying rock layer group of the coal seam is blasted by adjusting the position of the charge section and the sealing length.

[0009] (4) Use a microseismic monitoring system to record and collect the waveform signals generated by the blasting, and then perform energy calculation;

[0010] (5) Compare the energy obtained in step (4) and determine the rock strata with the highest energy as the energy accumulation layer.

[0011] Furthermore, in step (1), the distance between the blasting location and the coal mining face is not less than 150m.

[0012] Furthermore, the diameter of the blasting hole in step (2) depends on the drilling equipment and geological conditions. When drilling strongly or moderately weathered rocks and stripping overburden, a large drill bit is used, and the diameter of the blasting hole is 100-165 mm. When drilling in medium-hard and hard rocks, a small drill bit is used, and the diameter of the blasting hole is 75-100 mm. When using a rock drill with a connecting rod, the diameter of the blasting hole is 50-75 mm. When using down-the-hole drilling, the diameter of the blasting hole is 90-120 mm.

[0013] The depth of the blasting hole is determined by the combined location of the opening and the closing position. The opening position is located near the shoulder of the roadway, and the closing position is determined according to the strata group divided in step (3). The depth of the blasting hole is the straight-line distance between the opening and closing positions.

[0014] Blasting hole inclination angle The hole location is determined by a combination of the opening and closing positions, and is calculated using the following formula:

[0015]

[0016] In the formula, h is the elevation difference between the opening position and the closing position of the blast hole, in meters;

[0017] l s This is the horizontal distance between the opening and closing positions of the blast hole, in meters (m).

[0018] The formula for calculating the charge quantity Q is:

[0019] Q = ql c ;

[0020] In the formula: q is the density of the linear charge of the explosive, in kg / m;

[0021] l c The total length of the explosive charge is in meters (m).

[0022] The sealing hole length shall be no less than one-third of the blast hole depth, and no less than 5m.

[0023] Furthermore, in step (3), the blasting requirements for the group blasting of the overlying rock strata of the coal seam are that the amount of explosives used in each rock strata is such that the energy of each rock strata is fully released and the amount of explosives used in each rock strata is equal.

[0024] Further, in step (4), the method for acquiring the waveform signal generated by the blast is as follows: an SOS microseismic monitoring system is installed in the coal mine. The SOS microseismic monitoring system includes an above-ground acquisition and recording device and multiple probes installed underground. The multiple probes are installed on the bottom plate of the coal seam to acquire the energy information released by the blast and record and store it through the monitoring system.

[0025] Further, in step (4), the energy solution process is as follows: the vibration velocity information v(t) and its energy density ε(r) are measured by the probe, where r is the distance from the source; the vibration wave is regarded as a spherical wave, the energy density ε(r) is calculated at a propagation radius of 500m, and the energy attenuation F(r)=(2r) is considered. 2n e α(2r-1) The formula for calculating the vibration energy E(r) is: E(r) = 10 6 πε(r)F(r).

[0026] This invention determines the blasting location, blasting parameters, and classifies the overlying strata into groups. The overlying strata are then blasted in groups, and a microseismic monitoring system is used to record and collect the waveform signals generated by the blasting. Energy calculations are then performed, and the strata group with the highest energy is identified as the energy accumulation layer. This provides a basis for subsequent fracture control, enabling a systematic study of energy accumulation layers from an energy calculation perspective. This fills a gap in the field and provides a theoretical research foundation and operational guidance for safe mine production. This invention can easily identify the location of the overlying energy accumulation layer without complex calculations and analysis, making it easier to implement in the field. It is simple, convenient, and highly operable. Attached Figure Description

[0027] Figure 1 This is a flowchart of the process of this invention;

[0028] Figure 2 This is a schematic diagram of the working state of blasting sandy mudstone formation in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the working state of blasting coarse-grained sandstone group in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the working state of blasting medium-grained sandstone group in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the working state of blasting mudstone formation in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the working state of blasting fine-grained sandstone in an embodiment of the present invention.

[0033] In the figure: 1. Sandy mudstone group, 2. Coarse-grained sandstone group, 3. Medium-grained sandstone group, 4. Mudstone group, 5. Fine-grained sandstone group, 6. Coal seam, 7. Explosive charging section. Detailed Implementation

[0034] The invention will now be further described with reference to the accompanying drawings.

[0035] like Figure 1 As shown, a method for determining the energy accumulation layer of the overlying strata includes the following steps:

[0036] (1) Determine the appropriate blasting location based on geological conditions and mining conditions at the working face;

[0037] (2) Determine the deep hole blasting construction parameters based on the rock strata properties and drilling equipment conditions. The construction parameters include the blasting hole diameter, blasting hole depth, blasting hole inclination angle, charge amount and sealing length.

[0038] (3) Based on the borehole columnar section drawn after sampling and analysis of the borehole core, several layers of rock with similar lithology in the overlying rock of the coal seam are divided into a rock layer group as a group of blasting targets, and the distance from the coal seam 6 is determined; the overlying rock layer group of the coal seam is blasted by adjusting the position of the charge section 7 and the sealing length.

[0039] (4) Use a microseismic monitoring system to record and collect the waveform signals generated by the blasting, and then perform energy calculation;

[0040] (5) Compare the energy obtained in step (4) and determine the rock strata with the highest energy as the energy accumulation layer.

[0041] To ensure the safety of the coal mining face, the blasting location in step (1) must be at least 150m ahead of the coal mining face.

[0042] As a preferred embodiment, the diameter of the blasting hole in step (2) depends on the drilling equipment and geological conditions. When drilling strongly or moderately weathered rocks and stripping overburden, a large drill bit is used, and the diameter of the blasting hole is 100-165 mm. When drilling in medium-hard and hard rocks, a small drill bit is used, and the diameter of the blasting hole is 75-100 mm. When using a rod drill, the diameter of the blasting hole is 50-75 mm. When using down-the-hole drill, the diameter of the blasting hole is 90-120 mm.

[0043] The depth of the blasting hole is determined by the combined location of the opening and the closing position. The opening position is located near the shoulder of the roadway, and the closing position is determined according to the strata group divided in step (3). The depth of the blasting hole is the straight-line distance between the opening and closing positions.

[0044] Blasting hole inclination angle The hole location is determined by a combination of the opening and closing positions, and is calculated using the following formula:

[0045]

[0046] In the formula, h is the elevation difference between the opening position and the closing position of the blast hole, in meters;

[0047] l s This is the horizontal distance between the opening and closing positions of the blast hole, in meters (m).

[0048] The formula for calculating the charge quantity Q is:

[0049] Q = ql c ;

[0050] In the formula: q is the density of the linear charge of the explosive, in kg / m;

[0051] l c The total length of the explosive charge is in meters (m).

[0052] The sealing hole length shall be no less than one-third of the blast hole depth, and no less than 5m.

[0053] In order to calculate the vibration energy more accurately, the blasting requirements for the group blasting of the overlying rock strata in step (3) are that the amount of explosives used in each rock strata is such that the energy of each rock strata is fully released and the amount of explosives used in each rock strata is equal.

[0054] As a preferred embodiment, in step (4), the method for acquiring the waveform signal generated by the blast is as follows: an SOS microseismic monitoring system is installed in the coal mine. The SOS microseismic monitoring system includes an above-ground acquisition and recording device and multiple probes installed underground. The multiple probes are installed on the bottom plate of the coal seam to acquire energy information released by the blast and record and store it through the monitoring system.

[0055] Specifically, in step (4), the energy solution process is as follows: the vibration velocity information v(t) and its energy density ε(r) are measured by the probe, where r is the distance from the source; the vibration wave is regarded as a spherical wave, the energy density ε(r) is calculated at a propagation radius of 500m, and the energy attenuation F(r)=(2r) is considered. 2n e α(2r-1) The formula for calculating the vibration energy E(r) is: E(r) = 10 6 πε(r)F(r).

[0056] Example:

[0057] (1) As Figure 2 As shown, taking a certain working face in a certain mine as an example, the first group of blasting operations is arranged 200m in front of the working face. In order to prevent mutual interference between blasting operations, the blasting locations of each group are spaced 20m apart.

[0058] (2) Based on the geological conditions and borehole columnar section, five rock strata groups above the coal seam were identified as blasting targets. From top to bottom, they are sandy mudstone group 1, coarse-grained sandstone group 2, medium-grained sandstone group 3, mudstone group 4 and fine-grained sandstone group 5, with rock strata heights of 13m, 9m, 6.5m, 5m and 4m, respectively. Since the roof rock strata group closest to coal seam 6 is thin and collapses with mining, there is no possibility of energy accumulation, so it is not selected as a blasting target.

[0059] (3) Determine reasonable deep-hole blasting construction parameters based on the rock strata properties and drilling equipment conditions, including blasting hole diameter, blasting hole depth, blasting hole inclination angle, charge quantity, and sealing length. Specific parameters are as follows:

[0060] ① Use a rock drill with a connecting rod; the diameter of the blasting hole is 75mm.

[0061] ② The opening location is near the shoulder of the roadway, and the final hole location is located in the stratum of the divided rock strata group. Two blasting holes are set with inclination angles of 45° and 135° respectively. The depths of the five blasting holes from top to bottom are 18.4m, 12.7m, 9.2m, 7.1m and 5.6m respectively.

[0062] ③ The amount of explosives used per rock layer is determined based on the actual conditions of the working face, which is 30 kg.

[0063] ④ The sealing lengths are set from top to bottom as follows, based on the hole depth and the stratigraphic position of the rock strata: 71.7m, 29m, 19.8m, 12.7m and 7.1m;

[0064] (4) Use a coal mine permitted charging machinery or blasting rod to push explosives, detonators or detonating cords into the charging section 7 in the blasting hole corresponding to the sandy mudstone group 1 to blast the sandy mudstone group 1.

[0065] (5) Figure 3 As shown, the explosives, detonators or detonating cords are pushed into the charging section 7 in the blasting hole corresponding to the coarse sandstone group 2 using a coal mine-permitted charging machine or ramming gun to blast the coarse sandstone group 2.

[0066] (6) Figure 4 As shown, the explosives, detonators or detonating cords are pushed into the charging section of the blasting hole corresponding to the medium-grained sandstone group 3 using a coal mine-permitted charging machine or ramming rod to blast the medium-grained sandstone group 3.

[0067] (7) Figure 5 As shown, the explosives, detonators or detonating cords are pushed into the charging section 7 in the blasting hole corresponding to mudstone group 4 using a coal mine-permitted charging machine or blasting rod to blast mudstone group 4.

[0068] (8) Figure 6As shown, the explosives, detonators or detonating cords are pushed into the charging section of the blasting hole corresponding to the fine-grained sandstone group 5 using a coal mine-permitted charging machine or ramming rod to blast the fine-grained sandstone group 5.

[0069] (9) The waveform signals generated by the blasting of each rock stratum group in steps (4) to (8) were recorded using a microseismic monitoring system, and the energy was calculated using the SOS microseismic monitoring system. The energy generated by these five blasting operations was found to be 1.28e. 4 J, 5.85e 4 J, 9.45e 3 J, 7.23e 3 J and 7.44e 3 J;

[0070] (10) By comparing the energy levels of the five blasting signals, it was found that the energy released was the most when the 9m coarse-grained sandstone group 2 was blasted, and it was much more than the other four groups. Therefore, the 9m coarse-grained sandstone group 2 was determined to be an energy accumulation layer.

Claims

1. A method for determining an overlying energy accumulation layer, characterized in that, Includes the following steps: (1) Determine the appropriate blasting location based on the geological conditions and the mining situation at the working face; (2) Determine the deep hole blasting construction parameters based on the rock strata properties and drilling equipment conditions. The construction parameters include the blasting hole diameter, blasting hole depth, blasting hole inclination angle, charge amount and sealing length. (3) Based on the borehole columnar section drawn after sampling and analysis of the borehole core, several layers of rock with similar lithology in the overlying rock of the coal seam are divided into a rock layer group as a group of blasting targets, and the distance from the coal seam is determined; the overlying rock layer group of the coal seam is blasted by adjusting the position of the charge section and the sealing length. (4) The waveform signal generated by the blasting was recorded and collected using a microseismic monitoring system, and the energy was calculated. The energy calculation process is as follows: the vibration velocity information is measured by the probe. and its energy density , The distance to the earthquake source; treating the seismic wave as a spherical wave, calculate the energy density. The value is based on a propagation radius of 500m, and energy attenuation is considered. Receive vibrational energy The calculation formula is: ; (5) Compare the energy obtained in step (4) and determine the rock formation with the highest energy as the energy accumulation layer.

2. The method for determining the energy accumulation layer of the overlying strata according to claim 1, characterized in that, In step (1), the distance between the blasting location and the coal mining face shall not be less than 150m.

3. A method for determining an overlying energy accumulation layer according to claim 1 or 2, characterized in that, The diameter of the blasting hole in step (2) depends on the drilling equipment and geological conditions. When drilling strongly or moderately weathered rocks and stripping overburden, a large drill bit is used, and the diameter of the blasting hole is 100-165 mm. When drilling in medium-hard and hard rocks, a small drill bit is used, and the diameter of the blasting hole is 75-100 mm. When using a rod drill, the diameter of the blasting hole is 50-75 mm. When using down-the-hole drill, the diameter of the blasting hole is 90-120 mm. The depth of the blasting hole is determined by the combined location of the opening and the closing position. The opening position is located near the shoulder of the roadway, and the closing position is determined according to the strata group divided in step (3). The depth of the blasting hole is the straight-line distance between the opening and closing positions. Blasting hole inclination angle The hole location is determined by a combination of the opening and closing positions, and is calculated using the following formula: ； In the formula, h is the elevation difference between the opening position and the closing position of the blast hole, in meters; This is the horizontal distance between the opening and closing positions of the blast hole, in meters (m). Charge The calculation formula is: ； In the formula: q is the density of the linear charge of the explosive, in kg / m; The total length of the explosive charge is in meters (m). The sealing hole length shall be no less than one-third of the blast hole depth, and no less than 5m.

4. The method for determining the energy accumulation layer of the overlying rock according to claim 1, characterized in that, In step (3), the blasting requirements for the group blasting of the overlying rock strata of the coal seam are that the amount of explosives used in each rock strata is such that the energy of each rock strata is fully released and the amount of explosives used in each rock strata is equal.

5. The method for determining the energy accumulation layer of the overlying rock according to claim 1, characterized in that, In step (4), the method for acquiring the waveform signal generated by the blast is as follows: an SOS microseismic monitoring system is installed in the coal mine. The SOS microseismic monitoring system includes an above-ground acquisition and recording device and multiple probes installed underground. The multiple probes are installed on the bottom plate of the coal seam to acquire the energy information released by the blast and record and store it through the microseismic monitoring system.

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