LU500326B1 - Method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception - Google Patents
Method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
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Abstract
The present invention discloses a method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception, and provides a comprehensive control method for extracting pressure relief gas through working face overlying thick and hard roof rock stratum deep-hole presplitting blasting pressure relief permeability increase and directional long borehole interception. A thick and hard roof breaking rule is analyzed, and a blasting pressure relief and permeability increase mechanism is explained. Explosives blast in hard rock, the blasting stress intensity is much higher than the pressure-resistant intensity of the rock, the rock around a blasting hole generates a great number of fractures under the effect of detonation stress waves, and is completely in a crushed state; and the integrality of the thick layer roof is damaged, and vertical gas migration channels of a coal seam and a goaf are increased. Through a directional long borehole of a roof overlying rock stratum, the gas inrushing into the goaf from an extracting coal seam group is intercepted. Meanwhile, stress redistribution around the blasting hole is realized, intensified strata pressure behaviors due to too long fault displacement of the thick and hard roof is avoided, an additional load of a support is reduced, and effects of protecting a roadway and improving the borehole gas extraction rate are achieved.
Description
BACKGROUND Technical Field The present invention relates to the field of coal mine gas extraction, and in particular to a method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception. Related Art During mining of a coal seam group under thick layer sandstone, main factors restricting safe stoping of a working face are roof control and gas control. With advancing of the working face, a hard roof forms a large area of hanging exposure without falling after coal seam stoping, so that the stress concentration degree of a fully-mechanized coal mining hydraulic support and roadway surrounding rock is increased. During falling of the large-area hanging exposure roof, serious equipment damage may be caused, and gas accumulated in a goaf 1s easy to instantly inrush to the coal mining working face. Meanwhile, the gas emission quantity closely adjacent to the coal seam is great, and a directional gas extraction borehole formed in the hard roof above the coal seam has no fracture development in the complete roof, so that the extraction difficulty of a great amount of high-concentration gas in the goaf is increased, the utilization rate of the borehole is low, the gas concentration in upper corners and return air flows of the working face is high, and the occurrence of accidents such as transfinite gas is caused. A method of forced roof cutting by deep-hole blasting is adopted to weaken the hard roof under the condition of not influencing the normal stoping of the working face, so that the thick and hard roof is broken while the fracture development of the rock stratum is increased, and a channel is provided for extracting the gas in the goaf through the directional long borehole of the roof, so as to achieve the purpose of controlling the gas. At present, there are rich research achievements in the field application of deep-hole blasting for coal seam permeability increase and blasting tunneling, but the research on blasting roof cutting is only introduction on blasting processes and parameters. There are few researches on enhancing the roadway maintenance effect by using deep-hole presplitting blasting pressure relief and improving the gas extraction rate at the same time under the condition of thick and hard roof short-distance coal seam group mining.
SUMMARY The objective of the present invention is to provide a method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception. By aiming at the problems of large-area hanging exposure of a mining coal seam roof, increase of stress received by a fully-mechanized coal mining hydraulic support, high gas concentration in upper corners, working face safety threatening and the like under the mining condition of a coal seam group under a thick and hard roof, the present invention provides thick and hard roof rock stratum deep-hole presplitting blasting pressure relief to protect a roadway, and meanwhile, blasting is performed to damage the integrality of the thick and hard roof, increase vertical gas migration channels, reduce an additional load of the support, and improve the gas extraction rate of a directional long borehole.
Meanwhile, through Qidong coal mine 8:31 working face overlying thick and hard roof deep-hole presplitting blasting application, it is showed that an integral maintenance effect of the roadway is good, the occurrence of crushing of the fully-mechanized coal mining hydraulic support is avoided, the proportion of pure extracted gas quantity in the gas emission quantity in the working face stoping period is between 40% and 60% for a long time, and the gas inrushing into a working face goaf from an adjacent coal seam is effectively intercepted. A working face air distribution quantity is 2450 m°/min, a return air gas concentration is 0.12% to the maximum extent, and is averagely 0.08%, safe and efficient production is realized, and the gas extraction quantity and extraction rate are improved.
The objective of the present invention can be achieved by the following technical solution: A method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception includes the following steps: Step 1, thick and hard roof deep-hole presplitting blasting pressure relief permeability increase S1: constructing a blasting borehole towards the inside of a hard roof according to design parameters in a stoping coal seam working face intake airflow roadway or an airway, and filling explosives for loosening blasting; S2: blasting the explosives in hard roof rock, and forming a crushing region and a fracture region in original rock not being influenced by mining after the blasting, so that the integrality of the rock is damaged, original fractures and a weak plane of the rock are expanded, the roof is weakened, and a rock stress concentration zone around a blasting hole is transferred towards a deep portion far away from the damaged rock; S3: enabling the rock to generate a great number of fractures under the effect of detonation stress waves, so that the thick and hard roof is able to timely collapse to reduce the range of a hanging roof and reduce a fracture interval and a weighting period of the roof; and S4: under the influence of a working face comprehensive stress field, enabling a fracture weak plane generated by deep-hole blasting and an original fracture weak plane to communicate with each other and act with each other, and extracting gas in a coal seam and goaf deep portion through a directional long borehole formed in the thick and hard roof by using fractures formed through deep-hole blasting; and Step 2: formation of directional long borehole for interception extraction on gas of working face S1: determining a drilling track of a drilling machine according to design parameters of a drill bit; S2: determining a directional hole construction process; and S3: performing analysis according to branching requirements of the drilling machine, and selecting a plurality of key points to determine a strike of the drilling track.
Further, after the blasting of S1 in Step 1, a great number of fractures are generated under the effect of the detonation stress waves, the rock around the blasting hole is in a completely crushed state, the integrality of the thick and hard roof 1s damaged, and vertical gas migration channels are increased.
Further, according to S1 in Step 2, by analyzing a working face gas source, a working face geological map and a gas emission position are analyzed to determine a directional drilling machine construction position and a drilling track control layer position.
Further, according to S2 in Step 2, the directional hole construction process is determined, and a fault zone and a blank region are avoided by analyzing a stratum and optimizing the drilling track.
Further, according to S3 in Step 2, in a constriction period, through analyzing the key point passing lithology of the borehole and the track, adjustment is timely performed to ensure the borehole to be constructed in accordance with a designed layer position.
Further, in Step 2, the directional long borehole is formed on the thick and hard roof, the gas on the blasting crack fractures is extracted, the working face goaf gas is effectively intercepted, the problems of emission of a great amount of gas from a lower adjacent coal seam and transfinite gas in upper corners are solved, and safe production of the working face is realized.
The present invention has the following beneficial effects:
1. By aiming at the problems of large-area hanging exposure of the roof, increase of stress received by the fully-mechanized coal mining hydraulic support, high gas concentration in upper corners, working face safety threatening and the like under the mining condition of the coal seam under the thick and hard roof, the present invention provides thick and hard roof rock stratum blasting pressure relief permeability increase to protect the roadway, and blasting is performed to damage the integrality of the roof, increase vertical gas migration channels, reduce an additional load of the support, and improve the gas extraction rate of the directional long borehole of the roof.
2. Through Qidong coal mine 8:31 working face overlying thick and hard roof deep-hole presplitting blasting application, it is showed that an integral maintenance effect of the roadway is good, the occurrence of crushing of the fully-mechanized coal mining hydraulic support is avoided, the proportion of pure extracted gas quantity in the gas emission quantity in the working face stoping period is between 40% and 60% for a long time, and the gas of an adjacent coal seam and the gas of a working face goaf are effectively intercepted. A working face air distribution quantity is 2450 m’/min, a return air gas concentration is 0.12% to the maximum extent, and is averagely 0.08%, safe and efficient production is realized, and the gas extraction quantity and extraction rate are improved.
BRIEF DESCRIPTION OF THE DRAWINGS The following further describes the present invention in detail with reference to the accompanying drawings.
Figure 1 is a schematic diagram of a thick and hard roof breaking rule of the present invention.
Figure 2 is a schematic diagram of a thick and hard roof breaking rule of the present invention.
Figure 3 is a schematic diagram of extracting blasting fracture gas through a directional long borehole of the present invention.
Figure 4 is a histogram of a 8,31 working face of the present invention.
Figure 5 is a schematic plane diagram of a borehole of the present invention.
Figure 6 is an A-A direction cross-section diagram in Figure 5.
Figure 7 is an arrangement plane diagram of a drilling track design of the present invention. Figure 8 is an arrangement cross-section diagram of the drilling track design of the present invention. 5 Figure 9 is a curve diagram of an original pressure of a 85# support of a working face of the present invention. Figure 10 is a schematic diagram of a relationship between a total gas extraction quantity and gas extraction through a long borehole of the present invention. Figure 11 is a schematic diagram of a proportion of a pure gas extraction quantity through the long borehole in a total extraction quantity of the present invention.
DETAILED DESCRIPTION The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some of the embodiments of the present invention rather than all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. A method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception, as shown in Figure 1, Figure 2 and Figure 3, includes the following steps: Step 1, thick and hard roof rock stratum deep-hole presplitting blasting pressure relief permeability increase Along with working face stoping, a basic roof rock stratum fractures. A basic roof rock block will generate a rotating sinking phenomenon at the tail end by using a coal-rock mass in front of the working face as a fulcrum and using a basic roof fracturing line as an axis under the effects of self weight and overlying rock stratum. In Figure 1 and Figure 2, Ea represents the coal seam ultimate elastic compression amount; max represents the basic roof rock stratum ultimate deflection; and Sy represents the goaf roof sinking amount. When a positive moment generated at a front end of the basic roof rock block is greater than a counter moment of a hydraulic support on the basic roof rock block, the basic roof rock block forms a moment difference, and it can be expressed by the following formula:
on, | In the above formula, Ee is the strike along the working face, and per meter of support controls the basic roof rock block to move a possessed work load; L represents the basic roof rock block length; L represents the weighting interval; Q is the gravity of per meter of basic roof rock block along the working face inclination, and Q = Lhy ; h is the basic roof rock stratum height; and 7 is the basic roof rock stratum volume weight. PL =-01 When 2, the point is an ultimate equilibrium point for controlling weighting movement of the basic roof rock block generated through self weight by the possessed work load of the hydraulic support, thus the following may be obtained:
QU Through deduction in conjunction with Figure 2, 25, 25, may be obtained. In the above formula, Si represents the basic roof tail end sinking quantity; and 5, represents the sinking amount above the working face after basic roof collapse. From the above formula, it can be known that working resistance bre of the fully-mechanized coal mining hydraulic support is relevant to L, h and Sy, and the working resistance of the hydraulic support is greater when the basic roof fracture length is longer and the mining height is greater. If the working face roof is a thick and hard roof, the fracture length is longer, once the roof fractures, the overlying rock stratum will integrally collapse to damage the mechanical equilibrium state of the goaf, the hydraulic support and a coal wall, and the mine pressure effect is strong. By reducing the hanging roof length of the basic roof, the support pressure of the roadway can be reduced. Step 2: formation of directional long borehole for interception extraction on gas of working face goaf According to deep-hole presplitting blasting, a blasting borehole is constructed towards the inside of a hard roof rock stratum according to design parameters in a stoping coal seam working face intake airflow roadway or an airway, and explosives are filled for loosening blasting. The explosives blast in hard roof rock, and a crushing region and a fracture region are formed in original rock not being influenced by mining after the blasting, so that the integrality of the rock is damaged, original fractures and a weak plane of the rock are expanded, the roof is weakened, and a rock stress concentration zone around the blasting hole is transferred towards a deep portion far away from the damaged rock, and the effective stress of the fully-mechanized coal mining hydraulic support and a roadway single prop is reduced. Meanwhile, the rock is enabled to generate a great number of fractures under the effect of detonation stress waves, so that the thick and hard roof is able to timely collapse to reduce the range of a hanging roof and reduce a fracture interval and a weighting period of the roof, an additional load of a roadside support and a deformation amount of roadway surrounding rock are reduced, and the goal of protecting the roadway is achieved.
Under the influence of a working face comprehensive stress field, a fracture weak plane generated by deep-hole blasting and an original fracture weak plane communicate with each other and act with each other. Gas in a coal seam and goaf deep portion is extracted through a directional long borehole formed in the thick and hard roof by using fractures formed through deep-hole blasting, and the gas emission quantity of the goaf and the adjacent coal seam towards the coal mining working face and the upper corners is reduced, so that the gas control effect is achieved.
Embodiment:
1. General situation of experimental working face As shown in Figure 4, Qidong coal mine is a coal and gas burst mine, and primary mineable coal seams are all burst coal seams. A 8,31 working face is a three-mining-area 82 coal first mining protected layer working face. Strike arrangement is performed. A strike length is 1100 m. “U”-shaped ventilation is adopted. Single strike long-wall backward comprehensive mechanized coal mining is performed. The histogram of the 8231 working face is as shown in Figure 3. An upper protecting layer 71 coal goaf is above the 8,31 working face, and a normal length is about 30 to 33 m. The working face roof is totally sandstone, has a firmness coefficient of 13 and a thickness of 24.65 to 31.88 m, belongs to an ultra-thick sandstone roof, and cannot easily collapse. After mining, a caving zone of the hard sandstone roof is not obvious, the hard roof forms large-area hanging exposure after coal seam stoping without collapse, serious impact damage can be caused on the roadway once falling occurs, the deformation amount of the roadway surrounding rock is great, the damage to the support is serious, and great difficulty is caused on the stability control of the surrounding rock. The upper and lower corner hanging roof area extends for 20 to 30 m in a hole cutting direction. Used ordinary high-position borehole and high-position drilling construction are limited by roof factors, and the extraction effect is poor.
A normal length of 9 coal under 82 coal is about 10 m, and the lithology is mainly argillaceous sandstone. The 9 coal is eroded by magmatic rock in this range, and a coal thickness is 0.74 to 4.60 m. The lower adjacent layer 9 coal is influenced by mining to generate pressure relief gas diffused to enter the goaf, a working face absolute gas emission quantity reaches 16 m*/min to the maximum extent, and the safe production of the working face is seriously restricted. The 8,31 working face has no special gas extracting roadway, a hole depth of a borehole constructed from a three-mining-area floor extracting roadway reaches 200 m or deeper, an ordinary drilling machine cannot construct in place, and additionally, the drilling precision is poor.
The working face gas control measure effect is comprehensively analyzed. Therefore, advanced deep-hole presplitting blasting on the 8:31 fully-mechanized coal mining face overlying thick and hard roof is provided, so that the hard roof is weakened, the falling performance of the hard roof is improved, the roof rock stratum fracture development is increased, and the roadway maintenance effect is enhanced. Meanwhile, by constructing a directional long borehole in the 9 coal roof, a final hole position of the borehole is located in a 8 coal roof, and the extracted blasting pressure relief gas is intercepted.
2. Blasting hole design and blasting process (1) Hole spacing A hole spacing calculation formula is as follows: E=Kr,f : In the above formula, K is the adjusting coefficient, and is generally 10 to 15; 72 is the hole radius; fis the rock Protodyakonov coefficient, and when the rock has a higher hardness degree, K takes a smaller value; and when the rock has a lower hardness degree, K takes a greater value. Under the condition of this experiment, E=10x455x107x3=1.4m_ (2) Hole tail end distance The hole tail end distance is determined by factors of the working face length, the roof lithology, the crack state and the like, and is generally 15 to 20 m. The hole tail end distance in this time of blasting is controlled at 16 m.
(3) Hole depth In order to ensure a roadway cross section not to be influenced by blasting, a sufficient long isolation zone must be reserved between a hole bottom and a roadway. When unidirectional drilling is adopted for blast hole formation, the hole depth is as follows:
S—sY Sp = = + [tan 6(S— s)] sing In the above formula, S is the working face length; s is the horizontal distance from the hole bottom of the hole to a roadway 7; & is the included angle between the hole and the roadway; and p is the included angle between the hole and the working face. (4) Blasting cycle interval With continuous advancing of the working face, the blasting cycle interval is determined to be 20 m according to principles that the blasting cycle interval shall not be greater than a periodic weighting interval and the blasting workload is reduced. Calculation is performed according to the above formula, in conjunction with basic roof falling interval, 4 blast holes are drilled in each group, the hole spacing is 1.4 m, the hole positions of the blast holes is 1 m away from the roof, and the blast hole formation diagrams are as shown in Figure 5 and Figure 6 (in the figures, A1, A2, A3 and A4 are blast hole numbers). In an outward direction from the first group, the blast hole spacing of each group is 20 m. Then, with the advancing of the working face, cycle blasting is performed on the advanced working face every 20 m. Table 1 Blasting hole parameters and explosive load os Roadway Blast | Blast 7 ngle — xplosive load Stemming| Primacord name hole hole |Azimuth Elevation Roll Total/ke| length/m /m number |depth/m | angle angle |number/hole gene I17,24N| A1 | 20 | 75° | 50° | 8 [29.92 intake 4862 | 9 | 9 | airflow 71.06 roadway | A4 | 56 | 75 | & | 35 935 | 15 | 15 | Table 2 Blasting explosive parameters Explosive tvne Detonator | Exploder |Connection| Initiation | Blasting Hole p'osIvE typ type model mode sequence | method |diameter/mm Millisecond Instant P65 1000 mm delay FMB-200 Serial |ignition and | Direct mine water-gel . . ; Se 91 ; electric model | connection |[simultaneous| initiation explosives LL ue detonator initiation
3. Roof comb-shaped directional long borehole design and construction
3.1 Roof comb-shaped directional long borehole design scheme As shown in Figure 7 and Figure 8, according to 8,31 working face peripheral roadway arrangement condition, in order to avoid directional borehole coal penetrating construction, the directional borehole is formed in the 9 coal overlying sandstone layer position. 3 main boreholes and 5 branched holes are designed in a drill field, the borehole final hole positions are controlled to be in downward positions of 5 to 8 m from the 8; coal roof (2 to 5 m from the 9 coal roof), and a downward range of 30 to 90 m from the 8:31 working face airway 1s covered.
Table 3 Directional long borehole design parameter table Hole Construction Hole drilling Hole drilling Final hole Final hole Hole | Control number layer osition (°) inclination osition (°) inclination | depth | layer position p angle (°) p angle (°) (m) position TE [Ton [a si ee [TT 6 [200 | 25 M ar [TT [seo [Pom the | 2# |9coalroof| 181 | 15 | 101 | | | 690 | portion L2-1# | | | | 101 | 71 | 450 FO coal
3.2 Roof comb-shaped directional long borehole construction technology (1) Roof drilling interception and working face gas control technology By analyzing the source of working face gas, it is determined that controlling the adjacent layer abnormal gas emission is a key measure to solve the problem of working face gas. By analyzing a geological map of the working face and the range of gas emission, the construction position of a directional drilling machine and the control layer position of the drilling track are determined. The drilling track is controlled to be in a range of 2 to 5 m from the 9 coal roof and a downward range of 90 m from the working face airway. The range is verified to be an effective gas control range through practice. (2) Directional comb-shaped borehole construction technology A directional hole construction process of optimizing the drilling track to avoid a fault zone, forming a comb-shaped branched shielding blank region and the like is adopted through analyzing the stratum. (3) Thin-rock-stratum borehole branching technology A spacing between 8; coal and 9 coal seams is relatively small (averagely 10 m), the layer position change of the coal seams is great, the borehole design layer position is located in a position of 2 to 5 m from the 9 coal roof, a borehole inclination direction control adjustable range is narrow (smaller than 5 m), and branched holes are more. By taking a 1# hole as an example, 2 or more branched holes need to be constructed. Through analysis according to branching requirements of the drilling machine, whether the borehole and branched hole construction can succeed or not is determined by the precise control of the layer position. A key point track precise analysis control mode is adopted for construction in the borehole design and construction period, and the strike of the drilling track is determined by selecting a plurality of key points. In the construction period, through analyzing the key point passing lithology of the borehole and the track, adjustment is timely performed to ensure the borehole to be constructed in accordance with the designed layer position
4. Analysis on interception extraction effect of directional long borehole in deep-hole presplitting blasting pressure relief
4.1. Blasting effect and mine pressure observation During 8:31 working face stoping, the goaf started to gradually fell on July 11, the pressure of a working face support obviously rosed on July 12, and the pressure trended to become normal till the middle shift on July 13 after entering the deep-hole presplitting blasting region. According to the measured pressure and mine pressure phenomenon, it was determined that the working face overlying rock stratum had fractured at the moment. The pressure observation result is as shown in Figure 9.
4.2 Gas extraction effect As shown in Figure 10 and Figure 11, the gas emission quantity in the working face stoping period and the air intake side long borehole gas extraction quantity have a positive correlation relationship. Additionally, the proportion of pure extracted gas quantity in the gas emission quantity in the working face stoping period is between 40% and 60% for a long time, and the working face gas is effectively intercepted. A working face air distribution quantity is 2450 m*/min, a return air gas concentration is 0.12% to the maximum extent, and is averagely 0.08%, and safe and efficient production of the working face is realized.
It is proved by practice that by using the advanced deep-hole presplitting blasting method, the supporting pressure of a large-span hanging roof on the fully-mechanized coal mining hydraulic support and the roadway can be relieved, and the impact effect of sudden falling of a long-distance large-area hard roof on the hydraulic support and the roadway is prevented. The technology of extracting gas by the directional long borehole intercepting of the roof solves the problems of emission of a great amount of gas from the lower adjacent coal seams, transfinite gas in upper corners and the like.
In the descriptions of this specification, a description of a reference term such as "an embodiment", "an example", or "a specific example" means that a specific feature, structure, material, or characteristic that is described with reference to the embodiment or the example is included in at least one embodiment or example of the present invention. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. In addition, the described specific features, structures,
materials, or characteristics may be combined in a proper manner in any one or more of the embodiments or examples.
The foregoing displays and describes basic principles, main features of the present invention and advantages of the present invention. A person skilled in the art may understand that the present invention is not limited to the foregoing embodiments. Descriptions in the embodiments and this specification only illustrate the principles of the present invention. Various modifications and improvements are made in the present invention without departing from the spirit and the scope of the present invention, and these modifications and improvements shall fall within the protection scope of the present invention.
Claims (6)
1. A method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception, comprising the following steps: Step 1, thick and hard roof rock stratum deep-hole presplitting blasting pressure relief permeability increase S1: constructing a blasting borehole towards the inside of a hard roof rock stratum according to design parameters in a stoping coal seam working face intake airflow roadway or an airway, and filling explosives for loosening blasting; S2: blasting the explosives in hard roof rock, and forming a crushing region and a fracture region in original rock not being influenced by mining after the blasting, so that the integrality of the rock is damaged, original fractures and a weak plane of the rock are expanded, a roof is weakened, and a rock stress concentration zone around a blasting hole is transferred towards a deep portion far away from the damaged rock; S3: enabling the rock to generate a great number of fractures under the effect of detonation stress waves, so that the thick and hard roof is able to timely collapse to reduce the range of a hanging roof and reduce a fracture interval and a weighting period of the roof; and S4: under the influence of a working face comprehensive stress field, enabling a fracture weak plane generated by deep-hole blasting and an original fracture weak plane to communicate with each other and act with each other, and extracting gas in a coal seam and goaf deep portion through a directional long borehole formed in the thick and hard roof by using fractures formed through deep-hole blasting; and Step 2: formation of directional long borehole for interception extraction on gas of working face goaf S1: determining a drilling track of a drilling machine according to design parameters of the borehole; S2: determining a directional hole construction process; and S3: performing analysis according to branching requirements of the drilling machine, and selecting a plurality of key points to determine a strike of the drilling track.
2. The method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception according to claim 1, wherein after the blasting of S1 in Step 1, a great number of fractures are generated under the effect of the detonation stress waves, the rock around the blasting hole is in a completely crushed state, the integrality of the thick and hard roof 1s damaged, and vertical gas migration channels are increased.
3. The method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception according to claim 1, wherein according to S1 in Step 2, by analyzing a working face gas source, a working face geological map and a gas emission position are analyzed to determine a directional drilling machine construction position and a drilling track control layer position.
4. The method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception according to claim 3, wherein according to S2 in Step 2, the directional hole construction process is determined, and a fault zone and a blank region are avoided by analyzing a stratum and optimizing the drilling track.
5. The method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception according to claim 4, wherein according to S3 in Step 2, in a constriction period, through analyzing the key point passing lithology of the borehole and the track, adjustment is timely performed to ensure the borehole to be constructed in accordance with a designed layer position.
6. The method for extracting pressure relief gas through thick and hard roof rock stratum blasting permeability increase and directional long borehole interception according to claim 1, wherein in Step 2, the directional long borehole is formed on the thick and hard roof, the gas on the blasting crack fractures is extracted, the working face goaf gas is effectively intercepted, the problems of emission of a great amount of gas from a lower adjacent coal seam and transfinite gas in upper corners are solved, and safe production of the working face is realized.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110327628.2A CN113027510A (en) | 2021-03-26 | 2021-03-26 | Method for extracting pressure-relief gas by blasting permeability-increasing directional long drill hole of thick and hard roof rock layer |
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| CN113653527A (en) * | 2021-09-17 | 2021-11-16 | 中煤科工集团重庆研究院有限公司 | Method for extracting top coal gas during fully mechanized top coal caving period of extra-thick coal seam |
| CN114893161A (en) * | 2022-05-05 | 2022-08-12 | 陕西彬长孟村矿业有限公司 | Multi-layer position directional drilling combined arrangement method |
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| CN111101998B (en) * | 2020-01-19 | 2021-03-19 | 山西晋城无烟煤矿业集团有限责任公司 | Method for intercepting gas extracted from directional long drill hole |
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