CN116771348A - Method for reducing dynamic pressure influence of main roadway in last mining and optimizing stoping line coal pillar - Google Patents
Method for reducing dynamic pressure influence of main roadway in last mining and optimizing stoping line coal pillar Download PDFInfo
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- CN116771348A CN116771348A CN202310508224.2A CN202310508224A CN116771348A CN 116771348 A CN116771348 A CN 116771348A CN 202310508224 A CN202310508224 A CN 202310508224A CN 116771348 A CN116771348 A CN 116771348A
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- 238000005065 mining Methods 0.000 title claims abstract description 82
- 239000003245 coal Substances 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000005553 drilling Methods 0.000 claims abstract description 153
- 239000011435 rock Substances 0.000 claims abstract description 51
- 238000005520 cutting process Methods 0.000 claims abstract description 48
- 230000005540 biological transmission Effects 0.000 claims abstract description 3
- 238000013461 design Methods 0.000 claims description 23
- 238000003825 pressing Methods 0.000 claims description 13
- 238000012360 testing method Methods 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 5
- 238000011835 investigation Methods 0.000 claims description 3
- 230000032798 delamination Effects 0.000 claims description 2
- 238000002347 injection Methods 0.000 claims description 2
- 239000007924 injection Substances 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000002787 reinforcement Effects 0.000 claims description 2
- 230000003014 reinforcing effect Effects 0.000 claims description 2
- 235000019738 Limestone Nutrition 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 239000006028 limestone Substances 0.000 description 4
- 238000005422 blasting Methods 0.000 description 2
- 238000009933 burial Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 238000004904 shortening Methods 0.000 description 1
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Abstract
The application discloses a method for reducing dynamic pressure influence of a main roadway in last mining and optimizing a stoping line coal pillar, which belongs to the field of coal mining and has the technical key points that: which comprises the following steps: firstly, arranging drilling sites at different positions of stoping roadways near stoping lines of more than two adjacent working surfaces, and drilling directional horizontal drilling holes parallel to the stoping lines in the hard top plate in opposite directions by using a kilometer drilling machine in the drilling sites, wherein the initial part of the track of the drilling holes is a curve, and the main part of the track is an approximately horizontal straight line; in order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling sites are uniformly distributed in two stoping roadways at the outermost sides of two or more adjacent working surfaces and drilling holes are oppositely implemented, so that horizontal drilling holes with roof cutting layers are drilled at the initial parts of the two stoping roadways; then, hydraulic fracturing is carried out in the horizontal drilling hole to cut off the hard roof, the stress transmission path of the roof is cut off, and the roof pressure is weakened, so that the stability of the surrounding rock of a main roadway is ensured, and meanwhile, the width of a coal pillar of a stoping line is shortened.
Description
Technical Field
The application relates to the field of coal mining, in particular to a method for reducing the dynamic pressure influence of a main roadway in the last mining and optimizing a stope coal pillar.
Background
When underground mining of a coal mine enters into an end mining stage (the working face is back-mined to the vicinity of a stoping line), the advanced supporting pressure formed by the back-mining of the working face moves forward along with the pushing of the working face, so that a large roadway is in a mining influence range, surrounding rock stability of the large roadway is directly influenced, underground transportation, ventilation, pedestrians and other works can be influenced when the roadway is seriously deformed, and particularly when the hard rock of a roof of a mined coal bed is thicker or the burial depth is larger, the dynamic pressure influence degree is larger, and the range is wider.
Therefore, the method for reducing the influence of the last mining on the roadway and improving the stability of surrounding rock is of great significance.
At present, the methods for improving the stability of the surrounding rock of the main roadway mainly comprise the following two methods:
(1) The mining influence is lightened by increasing the width of the coal pillar of the stoping line, the conventional 30 m-50 m is increased to 60-100 m or even 150m, and the distance is used for replacing the surrounding rock of the main roadway for stabilization. However, according to field investigation, under the conditions of hard roof strata, large mining height working surface, large burial depth and the like, the effect of increasing the width of the coal pillar of the stoping line on reducing the influence of dynamic pressure is not obvious, and if the width of the coal pillar of the roadway is continuously and greatly increased, a great deal of loss of coal resources is caused.
(2) And cutting the roof in the pre-digging retracting channel for pressure relief. In order not to influence the normal pushing of the stoping working face during the last mining, the working face often digs a retracting channel in advance before pushing to the stoping line, so that the mutual influence of the stoping operation and the retracting channel operation is avoided. In order to reduce the mining influence of working face advanced supporting stress on a main roadway during final mining, a hard top plate above a coal bed is cut off in a pre-excavated withdrawal channel by a roof cutting pressure relief method, so that the cantilever beam length during final mining is shortened, and the dynamic pressure influence on the main roadway is reduced.
The conventional roof cutting pressure relief method in the retracement channel comprises two methods of deep hole pre-splitting blasting and hydraulic fracturing, and the methods have better effect on protecting a major roadway in field implementation, but have two defects: one is to cut the hard top plate of the basic roof by vertically drilling holes in the retracting passage, but the drilling work amount of the weak top plate is increased intangibly, and especially when the roof cutting height is more than 30m, the construction cost is greatly increased. In addition, the blasting also has certain potential safety hazards; secondly, the pre-digging retracting channel is seriously deformed and damaged by the influence of advanced supporting stress during the last mining of the working face, so that the problems of roof fall, large moving amount of two sides, serious bottom drum, difficult supporting, difficult control of a top plate and the like are easily caused, and accidents such as pressing frames, coal wall sides and the like are easily caused when the working face is pushed into the retracting channel, thereby influencing the safe and efficient production of the coal mine.
Therefore, the patent provides a method for reducing the dynamic pressure influence of a main roadway and optimizing a stoping line coal pillar during non-mining, specifically, drill sites are arranged at different positions near the initial design stoping line, a kilometer drill in the drill sites is utilized to drill setting horizontal drill holes into a hard top plate along the length direction of a working surface, the horizontal drill holes are distributed at different positions away from the initial design stoping line, then hydraulic fracturing is carried out in the horizontal drill holes to cut off the hard top plate, the pressure of the main roadway surrounding rock is reduced, so that the main roadway surrounding rock is ensured to be stable, and meanwhile, the width of the stoping line coal pillar is shortened.
Disclosure of Invention
The application provides a method for reducing dynamic pressure influence of a main roadway in last mining and optimizing a stope coal pillar, and aims to solve the problems in the prior art.
A method for reducing dynamic pressure influence of a main roadway in end mining and optimizing a stope coal pillar comprises the following steps:
firstly, drill sites are arranged at different positions of stoping roadways near two or more adjacent working surfaces, a kilometer drill in each drill site is utilized to drill directional horizontal drill holes parallel to the stoping lines into a hard top plate, the initial part of the track of the drill holes is a curve (the drill holes in the range are not in a roof cutting layer), the main part of the drill holes are approximately horizontal straight lines, in order to ensure that the hard top plate of the whole working surface can be completely cut off, drill sites are uniformly distributed in two stoping roadways at the outermost sides of the two or more adjacent working surfaces, and the drill holes are oppositely implemented, so that the horizontal drill holes with roof cutting layers are drilled at the initial parts;
and then, carrying out hydraulic fracturing in the horizontal drilling hole to cut off the hard roof, cutting off the stress transmission path of the roof, weakening the pressure of the roof, ensuring the stability of the surrounding rock of the main roadway, and shortening the width of the coal pillar of the stoping line.
A method for reducing dynamic pressure influence of a main roadway in end mining and optimizing a stope coal pillar comprises the following steps:
s1, collecting basic data of a stope face and a mining-affected main roadway;
s2, testing geomechanical characteristics of surrounding rock of a large roadway to be protected, wherein the method comprises the following steps: the lithology of the tunnel roof and the layer thickness, the physical and mechanical properties of surrounding rock and the ground stress state;
s3, designing kilometer horizontal drilling parameters and hydraulic fracturing parameters;
the required design kilometer horizontal drilling parameters include: the drilling site position, the relative positions of horizontal drilling holes and stoping lines, the distance between the horizontal drilling holes and stoping lines, the number of drilling holes and the drilling layer position;
the desired design hydraulic fracturing parameters include: hydraulic pressure, direction of fracturing, fracturing section;
s4, constructing a first group of kilometer horizontal drilling holes on site at the original design stoping line position according to design parameters, and developing hydraulic fracturing;
and S5, continuously stoping when the working face is pushed to the original design stoping line, simultaneously reinforcing anchor ropes on two sides of the main roadway, and monitoring surrounding rock deformation damage conditions of the main roadway to be protected in real time.
S6, optimizing the width of the stope coal pillar: before the working face is pushed to the preset group position roof cutting position each time, if the main roadway is deformed, stopping working face stoping, and optimizing the width of the stoping line to be the distance between the new stoping line and the first group roof cutting position;
further, the step S1 includes: the method for on-site investigation of the geological profile of the mine engineering and collection of basic data of the stope face and the mining-affected major road specifically comprises the following steps: a main roadway driving operation rule, a working face stoping operation rule, a drilling histogram, a mining engineering plan, hydrogeological conditions, structural conditions and mining influence conditions.
Further, the step S2 includes: and (3) testing and analyzing geomechanical characteristics of surrounding rocks of the large roadway to be protected, such as lithology of a roadway roof, layer thickness, physical and mechanical characteristics of the surrounding rocks, ground stress state and the like. And then determining the horizon and thickness of the hard rock stratum playing a key role in pressing the working face according to the mining square drilling histogram, the previous stope working face pressing step distance, the coal seam mining height and the goaf crushing expansion coefficient.
Further, the step S3 includes: the required design kilometer horizontal drilling parameters are determined by combining the lithology and thickness of the hard top plate, the collapse angle of the hard top plate and the ground stress test result. The drilling layer position is determined according to a mining square drilling histogram, a coal seam mining height, a goaf crushing expansion coefficient, a previous stope working face pressing step distance, a hard rock stratum layer playing a key role in working face pressing and the like; the drill site positions are the positions of two side stoping roadways corresponding to the horizontal drill holes of which the tops are planned to be cut; the horizontal drilling intervals are 5-20 m, 1-5 groups are arranged, and the specific number is determined according to deformation and damage conditions of the large roadway surrounding rock after roof cutting. The desired design hydraulic fracturing parameters need to be determined in combination with the thickness of the hard formation, uniaxial compressive strength, and the results of the earth stress test.
Further, the step S4 includes: the method comprises the steps of setting a first drilling field at an original design stoping line, installing a kilometer directional drilling machine in the drilling field, and then drilling directional horizontal drilling holes parallel to the stoping line in a hard top plate from the first drilling field by utilizing the kilometer directional drilling machine in the drilling field, wherein the track initial part of the drilling holes is a curve (the drilling holes in the range are not in a roof cutting layer), the main body part is approximately a horizontal straight line, and in order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling fields are arranged in two stoping roadways at the outermost sides of two or more adjacent working surfaces and drilling holes are implemented in opposite directions, so that the horizontal drilling holes with roof cutting layers are drilled at the initial parts.
Further, the spacing of the horizontal boreholes in step S4 is determined according to the formation conditions such as the thickness, lithology, strength, structure, ground stress, etc. of the hard formation, as well as the fracturing process, parameters, capability of the fracturing equipment, etc. to form an effective fracture network. The number of perforations in each drill site is related to the thickness of the cut rigid top plate:
drilling 1 hole in the vertical direction when the thickness of the cut hard top plate is smaller than 5 m;
and 2 drilling holes are drilled in the vertical direction when the thickness of the cut hard top plate is 5-10 m.
Further, step S5 includes:
the working face is pushed to the original design stoping line to continue stoping, a high-pressure water injection pump is arranged in a drilling site, and hydraulic fracturing is started in the drilling site after drilling of one drilling site is finished; the drilling holes are arranged in the hard rock stratum, each drilling hole is subjected to back-type repeated fracturing, every 10-30 m of the hole is subjected to fracturing, the fracturing time is not less than 30min each time, the water head direction during fracturing is necessarily perpendicular to the top plate of the roadway, namely the vertical direction, the fracturing is stopped when the water pressure suddenly and greatly drops, and the fracturing of the hard rock stratum in the horizontal drilling hole is repeatedly completed; and meanwhile, anchor rope reinforcement is carried out on the two sides of the main roadway, and deformation and damage conditions of surrounding rocks of the main roadway to be protected are monitored in real time. Such as roof delamination, roof subsidence, bottom bulging, and toe-in.
Further, step S6 includes: before the working face is pushed to the second set of roof cutting positions, if the main roadway is deformed, stopping working face stoping, and optimizing the width of the stoping line to be the distance between the new stoping line and the first set of roof cutting positions; when the working face is pushed to the second group of roof cutting positions, if the main roadway is not deformed, the second group of horizontal drilling holes and hydraulic fracturing thereof are started to be implemented, and the continuous back mining is continued, so that the main roadway is reciprocated to start deformation, and the width of the optimal stoping line is the distance between the new stoping line and the first group of roof cutting positions. Comprehensively considering the width of a coal pillar of a non-mining stop-mining line, the stress of the coal pillar of the stop-mining line after the stop-mining, the deformation of a working face after the stop-mining, the advanced stress influence range of the working face, the integrity of the coal pillar and the development degree of roadway cracks, wherein the distance of the non-mining stop-mining line is 10-30 m when a thin coal seam (below 1.3 m) is mined; when the medium-thickness coal seam (1.3-3.5 m) is mined, the distance of the mining stopping line is 30-60 m; when the thick coal seam (3.5-8 m) is mined, the distance of the last mining stop line is 60-90 m; when the super-thick coal seam (more than 8 meters) is mined, the distance of the last mining stop line is 90-120 meters.
The application has the beneficial effects that:
first, the basic concept of the present application is: the application breaks through the conventional internal roof cutting and pressure relief of a pre-digging retracting channel during the final mining period, and solves the problem that the vertical roof cutting and drilling of the traditional construction are affected by a plurality of operations in a working surface.
Second, the second inventive concept of the present application is that: the vertical roof cutting in the traditional construction needs to be perforated to reach the key hard rock stratum through the soft rock horizon, and especially when the roof cutting height reaches more than 30m, the drilling engineering quantity of the weak top plate is increased, and the problem of large drilling engineering quantity is caused. In the kilometer directional horizontal drilling process, the key hard rock stratum is directly reached through directional holes, and horizontal drilling is carried out in the hard rock stratum, so that the drilling engineering quantity is reduced.
Third, a third inventive concept of the present application is that: considering the width of the coal pillar of the stoping line of the last mining, the stress of the coal pillar of the stoping line of the mining, the deformation of the working face of the stoping line of the mining, the advanced stress influence range of the working face, the integrity of the coal pillar and the development degree of roadway cracks, and the distance of the stoping line of the last mining is 10-30 m when the thin coal seam (below 1.3 m) is mined; when the medium-thickness coal seam (1.3-3.5 m) is mined, the distance of the mining stopping line is 30-60 m; when the thick coal seam (3.5-8 m) is mined, the distance of the last mining stop line is 60-90 m; when the super-thick coal seam (more than 8 meters) is mined, the distance of the last mining stop line is 90-120 meters. The construction information is provided for the first time by the application.
Fourth, the implementation of the present application: in the first example, two groups of 8 horizontal drilling holes are drilled in the cutting top layer bit according to the thickness of the cutting top layer bit, lithology and other geological information, one group is positioned at the cutting top layer bit of 2.3m, and the other group is positioned at the cutting top layer bit of 4.6 m. The width of the coal pillar of the stoping line is optimized from 120m to 90m in the past after the method is adopted, and the width is shortened by 30m. In the second example, 4 horizontal drilling holes are designed in total according to geological information such as the thickness of the top-cutting layer bit and lithology. The width of the coal pillar of the stoping line is optimized from 110m to 80m in the past after the method is adopted, and the width is shortened by 30m. In the third example, two groups of 6 horizontal drilling holes are drilled in the cutting top layer bit according to the thickness of the cutting top layer bit, lithology and other geological information, one group is located at the cutting top layer bit of 2.7m, and the other group is located at the cutting top layer bit of 7.5 m. The width of the coal pillar of the stoping line is optimized from 80m to 56m, and the width is shortened by 24m.
Drawings
Fig. 1 is a schematic design of example 1.
FIG. 2 is a section I-I of FIG. 1.
FIG. 3 is a section II-II of FIG. 1.
Fig. 4 is a schematic design of example 2.
FIG. 5 is a section I-I of FIG. 4.
FIG. 6 is a section II-II of FIG. 4.
Fig. 7 is a schematic design of example 3.
FIG. 8 is a section I-I of FIG. 7.
FIG. 9 is a section II-II of FIG. 7.
Detailed Description
In order that the above-recited objects, features and advantages of the present application will be more clearly understood, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, without conflict, the embodiments of the present application and features in the embodiments may be combined with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than those described herein, and therefore the scope of the present application is not limited to the specific embodiments disclosed below.
The following description of the embodiments of the application is made with reference to the accompanying drawings.
Embodiment one: fully-mechanized caving face for charcoal kiln lawn coal industry
As shown in fig. 1-3: the application provides a method for reducing the dynamic pressure influence of a main roadway in the last mining and optimizing the width of a coal pillar of a stoping line by combining a directional horizontal drill with hydraulic fracturing roof pressure relief, which comprises the following steps:
and I, researching the geological profile of mine engineering on site, testing and analyzing the geomechanical characteristics of surrounding rock of a roadway to be protected, such as a rock stratum structure and thickness thereof, physical and mechanical properties of the surrounding rock, hydrogeological conditions, structural conditions, mining influence conditions and the like, measuring the ground stress of the roadway by adopting a hydraulic fracturing method, and knowing that the maximum main stress is horizontal stress, the maximum main stress is 15.8MPa, the minimum main stress is horizontal stress, the maximum main stress is 8.5MPa, and the minimum main stress is parallel to the axial direction of the roadway.
Step II, according to the mining square drilling histogram, the primary initial pressure step distance of the back mining working face of 23.0m, the coal thickness of 5.85m (fully mechanized caving mining is adopted, the mining height is 3.1m, the coal caving height is 2.75 m) and the goaf crushing expansion coefficient is 1.4, the limestone which is 15.1m away from the tunnel roof and plays a key role in pressing the working face is determined, and the rock stratum thickness is 7.0m.
Step III, designing kilometer horizontal drilling parameters and hydraulic fracturing parameters, wherein the kilometer horizontal drilling parameters are specifically: designing the length of drilling holes to be 200m according to the height of the cut top, and drilling 2 drilling holes in each drilling site; the hydraulic fracturing parameters are designed as follows: the hydraulic pressure is 20MPa and the fracturing section is to ensure that the fracture penetrates the hard formation.
And IV, after the height of the top cutting layer position, the length and the number of the drilling holes are determined, a first drilling field is arranged from a stoping line, a kilometer directional drilling machine is installed in the drilling field, then drilling is started from the first drilling field, and each drilling field drills 1 drilling hole at the vertical heights of 2.3m and 4.6m of the top cutting layer position. The trajectory of the borehole is curved at the beginning and approximately horizontal at the body. In order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling sites are arranged in two stoping tunnels at the outermost sides of two or more adjacent working surfaces and drilling holes are carried out in opposite directions, so that horizontal drilling holes with roof cutting layers are drilled at the initial parts of the two stoping tunnels.
Step V, continuously stoping when the working face is pushed to an original design stoping line, arranging a high-pressure water injection pump in a drilling site, and starting hydraulic fracturing in the drilling site after drilling of one drilling site is finished; the drilling holes are arranged in the hard rock stratum, each drilling hole is subjected to back-type repeated fracturing, the fracturing is carried out once every 10-30 m in the hole, the fracturing time is not less than 30min each time, the water head direction is necessarily perpendicular to the top plate of the roadway during fracturing, the fracturing is stopped when the water pressure suddenly and greatly drops, and the fracturing of the hard rock stratum in the horizontal drilling hole is repeatedly carried out until the fracturing is completed; and meanwhile, anchor rope reinforcement is carried out on the two sides of the main roadway, and deformation and damage conditions of surrounding rocks of the main roadway to be protected are monitored in real time. Such as roof delamination, roof subsidence, bottom bulging, and toe-in.
And step VI, along with the continuous stoping of the working surface, arranging a second drilling site at a position 10m away from the first drilling site, continuously drilling a horizontal drilling hole and developing hydraulic fracturing, and repeating the steps until the deformation rate of the surrounding rock of the main roadway has a slight rising trend through mine pressure monitoring when the surrounding rock is in the vicinity of a fourth drilling site (30 m away from the first drilling site), and immediately stopping stoping. Therefore, after the fully-mechanized caving face is acted by the method, the width of the coal pillar of the stoping line is optimized from 120m to 90m, and is shortened by 30m.
Embodiment two: fully-mechanized caving face for coal industry
As shown in fig. 1-3: the application provides a method for reducing the dynamic pressure influence of a main roadway in the last mining and optimizing the width of a coal pillar of a stoping line by combining a directional horizontal drill with hydraulic fracturing roof pressure relief, which comprises the following steps:
and I, researching the geological profile of mine engineering on site, testing and analyzing the geomechanical characteristics of surrounding rock of a roadway to be protected, such as a rock stratum structure and thickness thereof, physical and mechanical properties of the surrounding rock, hydrogeological conditions, structural conditions, mining influence conditions and the like, measuring the ground stress of the roadway by adopting a hydraulic fracturing method, and knowing that the maximum main stress is horizontal stress, the maximum main stress is 20.8MPa, the minimum main stress is horizontal stress, the maximum main stress is 11.8MPa, and the minimum main stress is parallel to the axial direction of the roadway.
Step II, according to the mining square drilling histogram, the primary initial pressure step distance of the stope face of the past 29.4m, the coal thickness of 6.5m (adopting fully-mechanized caving mining, the mining height of 3.2m, the coal caving height of 3.3 m) and the goaf crushing expansion coefficient of 1.2, the limestone which is 12.2m away from the tunnel roof and plays a key role in pressing the face is determined, and the rock stratum thickness is 5.0m.
Step III, designing kilometer horizontal drilling parameters and hydraulic fracturing parameters, wherein the kilometer horizontal drilling parameters are specifically: designing the length of drilling holes to be 350m according to the height of the cut top, and drilling 1 drilling hole in each drilling site; the hydraulic fracturing parameters are designed as follows: the hydraulic pressure is 30MPa and the fracturing section is to ensure that the fracture penetrates the hard formation.
And IV, after the height of the top cutting layer and the length and number of the drill holes are determined, setting a first drill site from the stoping line, installing a kilometer directional drilling machine in the drill site, and then starting to drill holes from the first drill site, wherein each drill site is drilled with 1 drill hole. The trajectory of the borehole is curved at the beginning and approximately horizontal at the body. In order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling sites are arranged in two stoping tunnels at the outermost sides of two or more adjacent working surfaces and drilling holes are carried out in opposite directions, so that horizontal drilling holes with roof cutting layers are drilled at the initial parts of the two stoping tunnels.
Step V, continuously stoping when the working face is pushed to an original design stoping line, arranging a high-pressure water injection pump in a drilling site, and starting hydraulic fracturing in the drilling site after drilling of one drilling site is finished; the drilling holes are arranged in the hard rock stratum, each drilling hole is subjected to back-type repeated fracturing, the fracturing is carried out once every 10-30 m in the hole, the fracturing time is not less than 30min each time, the water head direction is necessarily perpendicular to the top plate of the roadway during fracturing, the fracturing is stopped when the water pressure suddenly and greatly drops, and the fracturing of the hard rock stratum in the horizontal drilling hole is repeatedly carried out until the fracturing is completed; and meanwhile, anchor rope reinforcement is carried out on the two sides of the main roadway, and deformation and damage conditions of surrounding rocks of the main roadway to be protected are monitored in real time. Such as roof delamination, roof subsidence, bottom bulging, and toe-in.
And step VI, along with the continuous stoping of the working surface, arranging a second drilling site at a position 10m away from the first drilling site, continuously drilling a horizontal drilling hole and developing hydraulic fracturing, and repeating the steps until the deformation rate of the surrounding rock of the main roadway has a slight rising trend through mine pressure monitoring when the surrounding rock is in the vicinity of a fourth drilling site (30 m away from the first drilling site), and immediately stopping stoping. Therefore, after the fully-mechanized caving face is acted by the method, the width of the coal pillar of the stoping line is optimized from 110m to 80m, and is shortened by 30m.
Embodiment III: fully-mechanized coal mining face for coal grinding
As shown in fig. 4-6: the application provides a method for reducing the dynamic pressure influence of a main roadway in the last mining and optimizing the width of a coal pillar of a stoping line by kilometer directional drilling, roof cutting and pressure relief, which comprises the following steps:
and I, researching the geological profile of mine engineering on site, testing and analyzing the geomechanical characteristics of surrounding rock of a roadway to be protected, such as a rock stratum structure and thickness thereof, physical and mechanical properties of the surrounding rock, hydrogeological conditions, structural conditions, mining influence conditions and the like, measuring the ground stress of the roadway by adopting a hydraulic fracturing method, and knowing that the maximum main stress is vertical stress, the maximum main stress is 11.5MPa, the minimum main stress is horizontal stress, the maximum main stress is 7.8MPa, and the maximum main stress is parallel to the axial direction of the roadway.
And II, determining limestone which is a hard rock layer playing a key role in pressing the working surface and is 10.0m away from a tunnel roof according to the mining square drilling histogram, the previous stope working surface pressing step distance of about 25m, the coal seam mining height of 2.65m and the goaf crushing expansion coefficient of 1.3, and the rock layer thickness of the limestone is 9.95m.
Step III, designing kilometer horizontal drilling parameters and hydraulic fracturing parameters, wherein the kilometer horizontal drilling parameters are specifically: the length of the drilling holes is 550m according to the cut top height, and each drilling field drills 1 drilling hole at the vertical heights of 2.7m and 7.5m of the determined horizon. The hydraulic fracturing parameters are designed as follows: the hydraulic pressure is 20MPa and the fracturing section is to ensure that the fracture penetrates the hard formation.
And IV, after the height of the top cutting layer position, the length and the number of the drilling holes are determined, a first drilling field is arranged from a stoping line, a kilometer directional drilling machine is installed in the drilling field, then drilling is started from the first drilling field, and each drilling field drills 1 drilling hole at the vertical heights of 2.7m and 7.5m of the top cutting layer position. The trajectory of the borehole is curved at the beginning and approximately horizontal at the body. In order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling sites are arranged in two stoping tunnels at the outermost sides of two or more adjacent working surfaces and drilling holes are carried out in opposite directions, so that horizontal drilling holes with roof cutting layers are drilled at the initial parts of the two stoping tunnels.
Step V, continuously stoping when the working face is pushed to an original design stoping line, arranging a high-pressure water injection pump in a drilling site, and starting hydraulic fracturing in the drilling site after drilling of one drilling site is finished; the drilling holes are arranged in the hard rock stratum, each drilling hole is subjected to back-type repeated fracturing, the fracturing is carried out once every 10-30 m in the hole, the fracturing time is not less than 30min each time, the water head direction is necessarily perpendicular to the top plate of the roadway during fracturing, the fracturing is stopped when the water pressure suddenly and greatly drops, and the fracturing of the hard rock stratum in the horizontal drilling hole is repeatedly carried out until the fracturing is completed; and meanwhile, monitoring surrounding rock deformation damage conditions of the main roadway to be protected, such as roof separation conditions, roof sinking amount, bottom drum amount, two-side moving amount and the like.
And step VI, along with the continuous stoping of the working surface, arranging a second drilling site at a position 12m away from the first drilling site, continuously drilling a horizontal drilling hole and developing hydraulic fracturing, and repeating the steps until the deformation rate of the surrounding rock of the main roadway has a slight rising trend through mine pressure monitoring when the surrounding rock is near a third drilling site (the distance of 24m away from the first drilling site), and immediately stopping stoping. Therefore, after the fully-mechanized caving face is acted by the method, the width of the coal pillar of the stoping line is optimized to 56m from 80m in the past, and the width is shortened by 24m.
The above examples are provided for convenience of description of the present application and are not to be construed as limiting the application in any way, and any person skilled in the art will make partial changes or modifications to the application by using the disclosed technical content without departing from the technical features of the application.
Claims (10)
1. The method for reducing the dynamic pressure influence of the main roadway in the last mining and optimizing the coal pillar of the stoping line is characterized by comprising the following steps of:
firstly, arranging drilling sites at different positions of stoping roadways near stoping lines of more than two adjacent working surfaces, and drilling directional horizontal drilling holes parallel to the stoping lines in the hard top plate in opposite directions by using a kilometer drilling machine in the drilling sites, wherein the initial part of the track of the drilling holes is a curve, and the main part of the track is an approximately horizontal straight line; in order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling sites are uniformly distributed in two stoping roadways at the outermost sides of two or more adjacent working surfaces and drilling holes are oppositely implemented, so that horizontal drilling holes with roof cutting layers are drilled at the initial parts of the two stoping roadways;
then, hydraulic fracturing is carried out in the horizontal drilling hole to cut off the hard roof, the stress transmission path of the roof is cut off, and the roof pressure is weakened, so that the stability of the surrounding rock of a main roadway is ensured, and meanwhile, the width of a coal pillar of a stoping line is shortened.
2. The method for reducing the dynamic pressure influence of the main roadway in the final mining and optimizing the coal pillar of the stoping line is characterized by comprising the following steps of:
s1, collecting basic data of a stope face and a mining-affected main roadway;
s2, testing geomechanical characteristics of surrounding rock of a large roadway to be protected, wherein the method comprises the following steps: the lithology of the tunnel roof and the layer thickness, the physical and mechanical properties of surrounding rock and the ground stress state;
s3, designing kilometer horizontal drilling parameters and hydraulic fracturing parameters;
the required design kilometer horizontal drilling parameters include: the drilling site position, the relative positions of horizontal drilling holes and stoping lines, the distance between the horizontal drilling holes and stoping lines, the number of drilling holes and the drilling layer position;
the desired design hydraulic fracturing parameters include: hydraulic pressure, direction of fracturing, fracturing section;
s4, constructing a first group of kilometer horizontal drilling holes on site at the original design stoping line position according to design parameters, and developing hydraulic fracturing;
s5, continuously stoping when the working face is pushed to an original design stoping line, simultaneously reinforcing anchor ropes on two sides of a main roadway, and monitoring surrounding rock deformation damage conditions of the main roadway to be protected in real time;
s6, optimizing the width of the stope coal pillar: before the working face is pushed to the preset group position roof cutting position each time, if the main roadway is deformed, stoping of the working face is stopped, and at the moment, the width of the stoping line is optimized to be the distance between the new stoping line and the first group roof cutting position.
3. A method for reducing the dynamic pressure effect of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the step S1 comprises: the method for on-site investigation of the geological profile of the mine engineering and collection of basic data of the stope face and the mining-affected major road specifically comprises the following steps: a main roadway driving operation rule, a working face stoping operation rule, a drilling histogram, a mining engineering plan, hydrogeological conditions, structural conditions and mining influence conditions.
4. A method for reducing the dynamic pressure effect of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the step S2 comprises: firstly, testing and analyzing geomechanical characteristics of surrounding rock of a large roadway to be protected: the lithology of the tunnel roof, the layer thickness, the physical and mechanical properties of surrounding rock and the ground stress state, and then the layer position and the thickness of the hard rock stratum playing a key role in pressing the working surface are determined according to the mining square drilling histogram, the previous stope working surface pressing step distance, the coal seam mining height and the goaf crushing expansion coefficient.
5. A method for reducing the dynamic pressure effect of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the step S3 comprises: the required design kilometer horizontal drilling parameters are determined by combining the lithology and thickness of the hard top plate, the collapse angle of the hard top plate and the ground stress test result; the drilling layer position is determined according to a mining square drilling histogram, a coal seam mining height, a goaf crushing expansion coefficient, a previous stope working face pressing step distance, a hard rock stratum layer playing a key role in working face pressing and the like; the drill site positions are the positions of two side stoping roadways corresponding to the horizontal drill holes of which the tops are planned to be cut; the horizontal drilling intervals are 5-20 m, 1-5 groups are arranged, and the specific number is determined according to deformation and damage conditions of the large roadway surrounding rock after roof cutting; the desired design hydraulic fracturing parameters need to be determined in combination with the thickness of the hard formation, uniaxial compressive strength, and the results of the earth stress test.
6. The method for reducing the dynamic pressure influence of the main roadway at the last mining and optimizing the stope coal pillar according to claim 2, wherein the step S4 comprises: the method comprises the steps of setting a first drilling field at an original design stoping line, installing a kilometer directional drilling machine in the drilling field, and then drilling directional horizontal drilling holes parallel to the stoping line in a hard top plate from the first drilling field by utilizing the kilometer directional drilling machine in the drilling field, wherein the track initial part of the drilling holes is a curve, the main body part is an approximately horizontal straight line, and in order to ensure that the hard top plate of the whole working surface can be completely cut off, drilling fields are arranged in two stoping roadways at the outermost sides of two or more adjacent working surfaces and drilling holes are implemented in opposite directions, so that the horizontal drilling holes with roof cutting layers are drilled at the initial parts.
7. The method for reducing the dynamic pressure influence of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the interval between horizontal drilling holes in the step S4 is determined according to the rock stratum conditions such as the thickness, lithology, strength, structure, ground stress and the like of a hard rock stratum, and the fracturing process, parameters, the capacity of fracturing equipment and the like so as to form an effective fracture network;
the number of perforations in each drill site is related to the thickness of the cut rigid top plate:
drilling 1 hole in the vertical direction when the thickness of the cut hard top plate is smaller than 5 m;
and 2 drilling holes are drilled in the vertical direction when the thickness of the cut hard top plate is 5-10 m.
8. The method for reducing the dynamic pressure influence of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the step S5 comprises:
the working face is pushed to the original design stoping line to continue stoping, a high-pressure water injection pump is arranged in a drilling site, and hydraulic fracturing is started in the drilling site after drilling of one drilling site is finished; the drilling holes are arranged in the hard rock stratum, each drilling hole is subjected to back-type repeated fracturing, every 10-30 m of the hole is subjected to fracturing, the fracturing time is not less than 30min each time, the water head direction during fracturing is necessarily perpendicular to the top plate of the roadway, namely the vertical direction, the fracturing is stopped when the water pressure suddenly and greatly drops, and the fracturing of the hard rock stratum in the horizontal drilling hole is repeatedly completed; and meanwhile, anchor rope reinforcement is carried out on the two sides of the main roadway, and deformation and damage conditions of surrounding rocks of the main roadway to be protected are monitored in real time. Such as roof delamination, roof subsidence, bottom bulging, and toe-in.
9. The method for reducing the dynamic pressure influence of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 2, wherein the method comprises the following steps of:
the step S6 includes:
before the working face is pushed to the second set of roof cutting positions, if the main roadway is deformed, stopping working face stoping, and optimizing the width of the stoping line to be the distance between the new stoping line and the first set of roof cutting positions;
when the working face is pushed to the second group of roof cutting positions, if the main roadway is not deformed, the second group of horizontal drilling holes and hydraulic fracturing thereof are started to be implemented, and the continuous back mining is continued, so that the main roadway is reciprocated to start deformation, and the width of the optimal stoping line is the distance between the new stoping line and the first group of roof cutting positions.
10. The method for reducing the dynamic pressure influence of a main roadway at the time of last mining and optimizing a stope coal pillar according to claim 9, wherein the method comprises the following steps of: the distance relation between the mining height and the mining stopping line is obtained by adopting the following formula:
when m is less than or equal to 1.3m, the value range of x is [10m,30m ];
when m is more than 1.3 and less than or equal to 3.5m, the value range of x is (30 m,60 m);
when m is more than 3.5 and less than or equal to 8m, the value range of x is (60 m,90 m);
when 8 < m, the value range of x is (90 m,120 m).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116988831A (en) * | 2023-09-27 | 2023-11-03 | 太原理工大学 | Roof fracture form-based coal mine initial mining period I-shaped filling method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116988831A (en) * | 2023-09-27 | 2023-11-03 | 太原理工大学 | Roof fracture form-based coal mine initial mining period I-shaped filling method |
| CN116988831B (en) * | 2023-09-27 | 2023-12-12 | 太原理工大学 | Roof fracture form-based coal mine initial mining period I-shaped filling method |
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