CN112096382A - Advanced grouting reinforcement method for narrow coal pillars of gob-side roadway - Google Patents

Advanced grouting reinforcement method for narrow coal pillars of gob-side roadway Download PDF

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Publication number
CN112096382A
CN112096382A CN202010863860.3A CN202010863860A CN112096382A CN 112096382 A CN112096382 A CN 112096382A CN 202010863860 A CN202010863860 A CN 202010863860A CN 112096382 A CN112096382 A CN 112096382A
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China
Prior art keywords
coal
grouting
probe
hole
drill hole
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CN202010863860.3A
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Chinese (zh)
Inventor
李桂臣
毕瑞阳
孙长伦
荣浩宇
许嘉徽
梁巨理
孙元田
李雯玉
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China University of Mining and Technology CUMT
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China University of Mining and Technology CUMT
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Priority to CN202010863860.3A priority Critical patent/CN112096382A/en
Publication of CN112096382A publication Critical patent/CN112096382A/en
Pending legal-status Critical Current

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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21CMINING OR QUARRYING
    • E21C41/00Methods of underground or surface mining; Layouts therefor
    • E21C41/16Methods of underground mining; Layouts therefor
    • E21C41/18Methods of underground mining; Layouts therefor for brown or hard coal
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells
    • E21B47/06Measuring temperature or pressure
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21CMINING OR QUARRYING
    • E21C37/00Other methods or devices for dislodging with or without loading
    • E21C37/06Other methods or devices for dislodging with or without loading by making use of hydraulic or pneumatic pressure in a borehole
    • E21C37/12Other methods or devices for dislodging with or without loading by making use of hydraulic or pneumatic pressure in a borehole by injecting into the borehole a liquid, either initially at high pressure or subsequently subjected to high pressure, e.g. by pulses, by explosive cartridges acting on the liquid
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • E21D11/105Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00Setting anchoring-bolts
    • E21D20/02Setting anchoring-bolts with provisions for grouting
    • E21D20/021Grouting with inorganic components, e.g. cement

Abstract

A method for reinforcing narrow coal pillars of a gob-side entry by advanced grouting comprises the steps of before stoping of a working face of an upper section of the gob-side entry, arranging a row of drill holes on one side of an upper section of the excavated upper section of the entry along the extending direction of the coal pillars; detecting the drill hole by using a drill hole sounding instrument; analyzing the compression degree of different depths of the coal pillar and the development condition of cracks in the coal body according to the obtained information data of the pressure and the displacement in the drill hole, directly performing grouting reinforcement operation on parts with larger crack development in the coal pillar, and performing fracturing operation on parts with smaller crack development in the coal pillar; performing fracturing operation on the small coal pillar fractures by using an electric pulse device; observing the cracking range of the shock wave until all the small coal pillar cracks in the whole upper section roadway are cracked; on the basis of the original anchor net support of the coal pillar, a grouting anchor rod is placed in the drill hole to perform grouting reinforcement on the interior of the coal pillar. The method can effectively realize the advanced reinforcement operation of the coal pillar.

Description

Advanced grouting reinforcement method for narrow coal pillars of gob-side roadway
Technical Field
The invention belongs to the technical field of surrounding rock control of a gob-side roadway in an underground coal mine, and particularly relates to a method for reinforcing narrow coal pillars of the gob-side roadway by means of advanced grouting.
Background
At the present stage, coal mining in China is mainly in a well mining mode, and the problem of instability of surrounding rocks of a roadway is one of the main problems of deep well mining. In the underground mining process, the phenomenon of surrounding rock deformation instability of a roadway caused by mining influence, roof pressure and the like seriously influences the safe and efficient production work of a coal mine. In a gob-side roadway, deformation and instability of a narrow coal pillar on one side of a stope face are common problems, in order to effectively solve the problem, the coal pillar is usually reinforced by adopting a grouting mode after being damaged, the mode is hysteretic grouting, and the whole coal pillar is broken seriously and even loses bearing capacity completely because the grouting time is too late, so that the grouting effect cannot reach the expected reinforcing effect, and the safety production work of a coal mine cannot be guaranteed. The other mode is advanced working face stoping and grouting, namely before stoping of the working face of the upper section, the coal pillar is not influenced by mining at the moment and is not damaged, but is influenced by mining when stoping of the working face, further the coal pillar is deformed and broken, the bearing capacity is reduced instantly, and stoping of the working face of the lower section is influenced, so that the coal pillar needs to be grouted and reinforced. Therefore, an effective advanced grouting method for the gob-side roadway is urgently needed, and advanced grouting reinforcement operation of the coal pillar can be effectively completed in a mode of increasing the porosity of the coal pillar in advance.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the advanced grouting reinforcement method for the narrow coal pillars in the gob-side roadway, which can effectively perform advanced grouting operation on the gob-side roadway, can effectively realize advanced reinforcement operation of the coal pillars, and further can ensure safe production work of a mine.
In order to achieve the purpose, the invention provides a method for reinforcing narrow coal pillars in gob-side roadways by means of advanced grouting, which comprises a drilling penetration sounding instrument and an electric pulse device, wherein the drilling penetration sounding instrument comprises a conveying rod, a lifter, a probe, a hand pump and a data acquisition instrument, the conveying rod is a telescopic rod piece, one end of the conveying rod is connected with the lifter, and the outer diameter of the conveying rod is smaller than the inner diameter of a drill hole to be detected; the lifter is arranged in the roadway at the upper section, is of a liftable structure, and has an adjustable pitching angle, so that the depth of the conveying rod entering the drilled hole can be adjusted, and the angle of the conveying rod can be adjusted to adapt to drilled holes at different angles; the probe is arranged at the upper end of the conveying rod, four radial mounting holes are uniformly formed in the top end of the probe along the whole body, oil passages communicated with the inner ends of the four radial mounting holes are formed in the probe, and oil inlets of the oil passages are formed in the surface of the probe; the number of the probes is four, the four probes are respectively installed in the four radial installation holes, and the four probes are pairwise distributed in the directions of the x axis and the y axis; the outer side of the inner end of the probe is provided with a piston ring and is in sliding sealing fit with the radial mounting hole through the piston ring, the length of the probe is smaller than the depth of the radial mounting hole, and the inner end of the probe is also connected with the bottom of the radial mounting hole through a tension spring; the outer part of the probe top end is arranged on the pressure sensor; a displacement sensor for detecting the extension length of the probe is arranged on the probe; the hand pump is arranged in the roadway of the upper section and is connected with the oil inlet on the probe through an oil way; the data acquisition instrument is connected with the displacement sensor and the pressure sensor through cables;
the electric pulse device comprises a push rod, an operating platform, a shock wave generator, a hole packer and a controller, wherein one end of the push rod is connected with the operating platform, and the outer diameter of the push rod is smaller than the inner diameter of a drilled hole; the operating platform is arranged in the roadway of the upper section and is used for controlling the adjustment of the telescopic length and the pitching angle of the push rod; the size of the shock wave generator is smaller than the inner diameter of the drill hole, and the shock wave generator is arranged at the other end of the push rod; the hole packer is of a cylindrical structure, is sleeved outside the push rod, is matched with the hole opening of the drill hole and is used for establishing sealing connection between the push rod and the hole opening of the drill hole; the hole packer is provided with a water injection port communicated with the inner cavity of the hole packer; the controller is connected with the operation table and the shock wave generator;
the method specifically comprises the following steps;
s1: before stoping along the working face of the upper section of the hollow roadway, when the coal pillars are not influenced by mining, arranging a row of drill holes at certain intervals along the extending direction of the coal pillars on one side of the excavated upper section of the roadway, wherein the depth of the drill holes is not more than the thickness of the reserved coal pillars;
s2: detecting the drill hole by using a drill hole sounding instrument; the conveying rod is placed into the drill hole by adjusting the lifter, and the probe is conveyed to a position to be detected in the drill hole; starting a hand-pressure pump to supply oil to the radial mounting hole through an oil way and an oil duct, wherein the oil liquid simultaneously pushes the four piston rings to move outwards, so that two probes in the x-axis direction are pushed to simultaneously extend out along the positive direction and the negative direction of the x-axis respectively, and two probes in the y-axis direction are pushed to simultaneously extend out along the positive direction and the negative direction of the y-axis respectively; after the probe slowly extends out, the end part of the probe is gradually contacted with the coal body in the coal pillar and is tightly pressed until the probe is deeply inserted into the coal body; the data acquisition instrument acquires signals in real time by using the pressure sensor and the displacement sensor, analyzes information data of pressure and displacement in the drill hole according to the acquired signals, and records and stores the information data; the connection between the hand pump and the oil circuit is disconnected, the probe retracts into the probe under the action of the tension spring, and the conveying rod is driven to retract by adjusting the lifter, so that the probe retracts to the next detection depth; sequentially obtaining the compression conditions and displacement information data of deep rock strata at different depths until the horizontal detection process of the whole drilling hole is completed;
s3: the data acquisition instrument analyzes the compression degree of different depths of the coal pillar and the development condition of cracks in the coal body according to the obtained information data of the pressure and the displacement in the drill hole, grouting reinforcement operation can be directly carried out on the part with larger cracks in the coal pillar, and steps S4 and S5 are sequentially carried out on the part with smaller cracks in the coal pillar;
s4: selecting a drill hole, performing fracturing operation on a small part of a coal pillar fracture by using an electric pulse device, controlling a push rod to extend into the bottom of the small part or the small part of the fracture in the drill hole by using an operation table, sealing the orifice of the drill hole by using a hole packer, and performing water injection operation through a water path connected to a water injection port; after the drill hole is filled with water, a power supply is switched on, the shock wave releases energy to the periphery in a circular diffusion mode through the circular shock wave generator, the shock wave energy releases a tearing effect on a coal pillar at the moment, the diffused shock wave forms an electro-hydraulic effect by combining with the water in the drill hole, the tearing type damage degree of the coal pillar is further increased, the cracks of the coal body are effectively increased, the shock operation is repeated by utilizing the shock wave, in the process, low-pressure water is continuously injected through the water injection port, constant water pressure is kept, the water enters the deep part of the coal body along the cracks generated by the shock wave, the shock wave can be further coupled into the coal body around the drill hole by utilizing the water, the water can serve as a propagation medium of the shock wave and also can play a role of protecting the shock wave generator, the shock operation is repeatedly carried out for multiple times until the cracks of the coal body are enlarged to a designated range, and the operation of, then, the push rod is contracted to the part with smaller growth of the next crack, the operation mode of the previous operation point is repeated, and the operation is sequentially carried out to the position 0.3m away from the hole opening, namely, the operation of drilling is completed; the controller can obtain the real-time extension distance of the shock wave through the shock wave generator, and further obtain the peripheral cracking range and display the peripheral cracking range on the display;
s5: observing the cracking range of the shock wave through a display connected with the controller, taking out the electric pulse device after the expected effect is achieved, performing the impact operation of the next adjacent drilling hole, repeating the operation of the step S4, judging whether the cracking range of the current drilling hole is communicated with the cracking range of the previous drilling hole or not according to the change condition of the water pressure, completing the impact operation of the drilling hole when the two adjacent cracking ranges are communicated, and continuing the cracking operation of the next drilling hole until all the small-coal-pillar-crack regions in the whole upper-section roadway are cracked, so that before the recovery of the working face of the upper section, the undisturbed coal pillars are cracked in advance;
s6: after the smaller part of the coal pillar cracks are completely cracked, the cracks in the coal pillar are increased to the size meeting the requirements, on the basis of the original anchor net support of the coal pillar, a grouting anchor rod is placed in a drill hole to perform grouting reinforcement on the interior of the coal pillar, a discharge hole is formed in each of two sides of the length direction of the grouting anchor rod, hole sealing rings are used for sealing the holes, grouting equipment is connected with the head end of the grouting anchor rod, grouting is performed on the deep part of the drill hole by the aid of the grouting equipment, slurry is diffused into the coal body along with the cracks to be cemented with the coal body to form a whole, after the grouting reaches a specified pressure range, pressure stabilization lasts for 10-15 min, and grouting operation is finished and is stopped; and other drill holes are sequentially grouted in the same grouting mode, so that the coal body in the whole coal pillar is formed into a whole again, and the bearing capacity and the stability of the coal pillar are improved.
Preferably, in step S6, the number of the drill holes in one row in the longitudinal direction is four, and the distance between two adjacent drill holes is 800 mm; the distance between the rows of drill holes in the longitudinal direction is 1000 mm; the drilling aperture is 75mm, slip casting stock diameter is 28mm, and length is less than drilling depth.
Further, a tracer is added to the grouting material in step S6, so that the slurry penetration range can be observed by the tracer.
Further, in order to ensure the bearing capacity and stability of the coal pillar after grouting, the grouting material is single-liquid cement slurry in step S6The cement slurry has a water-cement mass ratio of 1: 0.75, and adding an additive in the stirring process; the admixture is 1: 6 mixture of water reducing agent and expanding agent, the slurry viscosity of the mixture is 33S, and the density of the mixture is 1.62G/CM3The calculus rate is 97%.
Preferably, the probe has a diameter of 54mm and the probe has a diameter of 5 mm.
Further, in order to improve grouting efficiency and ensure grouting effect, in step S6, grouting pressure is 1.0 to 2.0 MPa.
Further, in order to improve the grouting effect, the width of the fracture after the fracturing work in steps S4 and S5 is not less than 3 times the diameter of the slurry particles.
The method adopts a mode of advanced grouting of narrow coal pillars in the gob-side roadway, the grouting time is reasonably selected, before stoping on the working face of an upper section, the coal pillars are not influenced by mining, at the moment, drill holes are distributed in the coal pillars, cracks are caused by electric pulse shock waves, the porosity of coal bodies is increased, slurry can smoothly enter the cracks, the coal pillars are effectively reinforced by the grouting mode, and the bearing capacity and the stability of the coal pillars in the gob-side roadway are improved. The coal pillar is detected in the early stage, so that the compression deformation condition and the fracture development condition of the coal pillar can be analyzed, grouting can be directly performed on the part with larger fracture development, and the electric pulse cracking mode is adopted on the part with smaller fracture development, so that the porosity of the coal pillar is effectively increased, slurry can smoothly enter the fracture, and the grouting reinforcement of the coal pillar is completed; when the probe is adopted for detection, each test is carried out on a vertical plane, and the probe is provided with four mutually-perpendicular probes for detection, so that the test direction can be effectively fixed, and the detection precision is effectively improved. The coal body is fractured by electric impact to form a fracture surface, so that the fractures of smaller parts can be effectively filled in the fractures in the coal body, the porosity of the coal pillar can be effectively increased, the inside of the coal body can be fully grouted, and the grouting reinforcement effect can be obviously improved. The time of shock wave repeated operation is very short, enables to send and splits the operation and can accomplish fast, efficient, simultaneously, utilizes the shock wave to send and splits the coal body, can not cause secondary pollution, and the power disturbance is little, can not damage original strut, simultaneously, can not pollute the air in the pit, and the security is high. According to the invention, the grouting reinforcement operation is performed in advance on the area of the coal pillar which is not influenced by mining, so that the coal pillar is not influenced by the mining operation in the subsequent mining process, and the coal pillar can have stable pressure for bearing the top plate. The method has the advantages of simple step operation, low cost, safety, reliability, accurate detection, high fracturing speed, controllable fracture range, stable grouting reinforcement and the like, effectively ensures the safe and efficient production work of the coal mine, and has wide application prospect. The method is also suitable for the problem of insufficient grouting caused by small cracks of the coal rock mass.
Drawings
FIG. 1 is a plan view of a face of the present invention prior to extraction;
FIG. 2 is a schematic structural view of the borehole penetrometer of the present invention;
FIG. 3 is a schematic view of the invention with the borehole engaged with a probe;
FIG. 4 is a schematic diagram of the probing process of the probe in the borehole penetrometer of the present invention;
FIG. 5 is a schematic view of the structure of the electric pulse device of the present invention;
FIG. 6 is a cross-sectional view of the coal body blast-induced cracking in the present invention;
FIG. 7 is a schematic view of the grouting bolt of the present invention in cooperation with a borehole;
FIG. 8 is a schematic view of the arrangement of the drilling and grouting bolts in the coal pillar of the present invention;
FIG. 9 is a plan view of the lower zone face extraction of the present invention;
fig. 10 is a schematic view of the structure of the probe in the present invention.
In the figure: 1. the coal pillar, 2, the drilling hole, 3, the lower section working face, 4, the electric pulse device, 5, the upper section roadway, 6, the hand pump, 7, the riser, 8, the conveying rod, 9, the probe, 10, the probe, 11, the cable, 12, the data acquisition instrument, 13, the oil circuit, 14, the controller, 15, the grout outlet, 16, the operation panel, 17, the shock wave generator, 18, the push rod, 19, the hole packer, 20, the water filling port, 21, the grouting anchor rod, 22, the upper section working face, 23, the lower section roadway, 24, the radial mounting hole, 25, the piston ring, 26, the extension spring, 27, the oil duct, 28, the oil inlet.
Detailed Description
The invention will be further explained with reference to the drawings.
As shown in fig. 1 to 10, the method for reinforcing the narrow coal pillar along the gob-side entry by means of advanced grouting comprises a drilling penetration sounding instrument and an electric pulse device 4, wherein the drilling penetration sounding instrument comprises a conveying rod 8, a lifter 7, a probe 9, a probe 10, a hand pump 6 and a data acquisition instrument 12, the conveying rod 8 is a telescopic rod, one end of the conveying rod 8 is connected with the lifter 7, and the outer diameter of the conveying rod is smaller than the inner diameter of a drill hole 2 to be detected; the lifter 7 is arranged in the roadway 5 at the upper section, the lifter 7 is of a liftable structure, and the pitching angle can be adjusted, so that the depth of the conveying rod 8 entering the drill hole 2 can be adjusted, and the angle of the conveying rod 8 can be adjusted to adapt to the drill holes 2 at different angles; the probe 9 is arranged at the upper end of the conveying rod 8, four radial mounting holes 24 are uniformly formed in the top end of the probe, an oil passage 27 communicated with the inner ends of the four radial mounting holes 24 is further formed in the probe 9, and an oil inlet 24 of the oil passage 27 is formed in the surface of the probe 9; the number of the probes 10 is four, the four probes 10 are respectively installed in the four radial installation holes 24, and the four probes are pairwise distributed in the x-axis direction and the y-axis direction; a piston ring 25 is arranged on the outer side of the inner end of the probe 10 and is in sliding sealing fit with the radial mounting hole 24 through the piston ring 25, the length of the probe 10 is smaller than the depth of the radial mounting hole 24, and the inner end of the probe is also connected with the bottom of the radial mounting hole 24 through a tension spring 26; the outside of the tip of the probe 10 is disposed at the pressure sensor; a displacement sensor for detecting the extending length of the probe 10 is arranged on the probe 9; the hand pump 6 is arranged in the roadway 5 of the upper section and is connected with an oil inlet 24 on the probe 9 through an oil way 13; the data acquisition instrument 12 is connected with the displacement sensor and the pressure sensor through a cable 11;
the electric pulse device 4 comprises a push rod 18, an operation table 16, a shock wave generator 17, a hole packer 19 and a controller 14, and preferably, the core of the controller 14 adopts a single chip microcomputer; one end of the push rod 18 is connected with the operating platform 16, and the outer diameter of the push rod is smaller than the inner diameter of the drill hole 2; the operating platform 16 is arranged in the roadway 5 of the upper section, and the operating platform 16 is used for controlling the adjustment of the telescopic length and the pitching angle of the push rod 18; the shock wave generator 17 is smaller than the inner diameter of the drill hole 2 and is arranged at the other end of the push rod 18; the hole packer 19 is of a cylindrical structure, is sleeved outside the push rod 18, is matched with the hole opening of the drill hole 2, and is used for establishing sealing connection between the push rod 18 and the hole opening of the drill hole 2; the hole packer 19 is provided with a water injection port 20 communicated with the inner cavity of the hole packer; the controller 14 is connected with the operation table 16 and the shock wave generator 17;
the method specifically comprises the following steps;
s1: before stoping along the working face 22 of the upper section of the hollow roadway, when the coal pillars 1 are not influenced by mining, arranging a row of drill holes 2 at a certain interval along the extending direction of the coal pillars 1 on one side of the excavated upper section of the roadway 5 of the upper section, wherein the depth of each drill hole 2 is not more than the thickness of the reserved coal pillar 1;
s2: detecting the drill hole 2 by using a drill hole sounding instrument; the conveying rod 8 is placed into the drill hole 2 by adjusting the lifter 7, and the probe 9 is conveyed to a position to be detected in the drill hole 2; starting the hand pump 6 to work, supplying oil into the radial mounting hole 24 through the oil way 13 and the oil duct 27, wherein the oil simultaneously pushes the four piston rings 25 to move outwards, further pushes the two probes 10 in the x-axis direction to simultaneously extend out along the positive direction and the negative direction of the x-axis respectively, and pushes the two probes 10 in the y-axis direction to simultaneously extend out along the positive direction and the negative direction of the y-axis respectively; after the probe 10 slowly extends out, the end part of the probe is gradually contacted with the coal body in the coal pillar 1 and is tightly pressed until the probe penetrates into the coal body; at the moment, the directions of the x axis and the y axis are equivalent to a pair of acting force reaction forces, so that a stable force is provided for the probe 10 during detection, and accurate data can be obtained; the data acquisition instrument 12 acquires signals in real time by using the pressure sensor and the displacement sensor, analyzes information data of pressure and displacement in the drill hole 2 according to the acquired signals, and records and stores the information data; the connection between the hand pump 6 and the oil circuit 13 is disconnected, the probe 10 retracts into the probe 9 under the action of the tension spring 26, and the conveying rod 8 is driven to retract by adjusting the lifter 7, so that the probe 9 retracts to the next detection depth; sequentially obtaining the compression conditions and displacement information data of the deep rock strata 3 with different depths until the horizontal detection process of the whole borehole 2 is completed;
s3: the data acquisition instrument 12 analyzes the compression degree of the coal pillar 1 at different depths and the development condition of cracks in the coal body according to the obtained information data of the pressure and the displacement in the drill hole 2, can directly perform grouting reinforcement operation on the part with larger cracks in the coal pillar 1, and sequentially performs steps S4 and S5 on the part with smaller cracks in the coal pillar 1;
s4: selecting a drill hole 2, performing fracturing operation on the small crack part of the coal pillar 1 by using an electric pulse device 4, controlling a push rod 18 to extend into the bottom of the small crack or small crack part in the drill hole 2 by using an operation table 16, sealing the orifice of the drill hole 2 by using a hole packer 19, and performing water injection operation through a water path connected to a water injection port 20; after the drill hole 2 is filled with water, a power supply is switched on, the shock wave releases energy to the periphery in a circular diffusion mode through the circular shock wave generator 17, the shock wave energy releases a tearing effect on the coal pillar 1 at the moment, the diffused shock wave forms an electro-hydraulic effect by combining with the water in the drill hole 2, the tearing type damage degree to the coal pillar 1 is further increased, the cracks of the coal body are effectively increased, the shock operation is repeated by using the shock wave, in the process, low-pressure water is continuously injected through the water injection port 20, constant water pressure is kept, the water enters the deep part of the coal body along the cracks generated by the shock wave, the shock wave can be further coupled into the coal body around the drill hole 2 by using the water, the water can serve as a propagation medium of the shock wave and can also play a role of protecting the shock wave generator 2, and multiple shock operations are repeatedly performed until the cracks of the coal body are enlarged to a designated range, completing the operation of the operation point, then retracting the push rod 18 to the part with smaller crack development, repeating the operation mode of the previous operation point, and sequentially operating to the position 0.3m away from the hole opening, namely completing the operation of one drilling hole 2; the controller 14 can obtain the real-time extension distance of the shock wave through the shock wave generator 17, further obtain the peripheral cracking range and display the peripheral cracking range on the display;
s5: observing the cracking range of the shock wave through a display connected to the controller 14, taking out the electric pulse device 4 after the expected effect is achieved, performing the impact operation of the next adjacent drill hole 2, repeating the operation of step S4, meanwhile, judging whether the cracking range of the current drill hole 2 is communicated with the cracking range of the previous drill hole 2 according to the change condition of the water pressure, completing the impact operation of the drill hole 2 when two adjacent cracking ranges are communicated, and continuing the cracking operation of the next drill hole 2 until all the small cracks of the coal pillar 1 in the whole upper section roadway 5 are cracked, so that the undisturbed coal pillar 1 is cracked in advance before the recovery of the upper section working face 22;
s6: after the smaller part of the coal pillar 1 cracks are completely cracked, the cracks in the coal pillar 1 are increased to meet the required size, on the basis of the original anchor net support of the coal pillar 1, a grouting anchor rod 21 is placed in a drill hole 2 to perform grouting reinforcement on the interior of the coal pillar 1, a slurry outlet 15 is arranged on each of two sides of the grouting anchor rod 21 in the length direction, hole sealing rings are used for sealing holes at the positions of the holes, grouting equipment is connected with the head end of the grouting anchor rod 21, grouting is performed on the deep part of the drill hole 2 by the aid of the grouting equipment, slurry is diffused into the coal body along with the cracks to be cemented with the coal body to form a whole, the grouting pressure is stabilized for 10-15 min after reaching a specified pressure range, grouting operation is completed, and grouting is stopped; and other drill holes 2 are sequentially grouted in the same grouting mode, so that the coal body in the whole coal pillar 1 is formed into a whole again, and the bearing capacity and the stability of the coal pillar 1 are improved.
Preferably, in step S6, the number of the drill holes 2 in one row in the longitudinal direction is four, and the distance between two adjacent drill holes 2 is 800 mm; the distance between the rows of drill holes 2 in the longitudinal direction is 1000 mm; the aperture of the drilling hole 2 is 75mm, the diameter of the grouting anchor rod 21 is 28mm, and the length of the grouting anchor rod is smaller than the depth of the drilling hole 2.
In step S6, a tracer is added to the grouting material to facilitate observation of the slurry penetration range by the tracer.
In order to ensure the bearing capacity and stability of the coal pillar after grouting, single-liquid cement slurry is selected as a grouting material in step S6, wherein the water-cement mass ratio of the single-liquid cement slurry is 1: 0.75, and adding an additive in the stirring process; the admixture is 1: 6 mixture of water reducing agent and expanding agent, the slurry viscosity of the mixture is 33S, and the density of the mixture is 1.62G/CM3The calculus rate is 97%.
Preferably, the probe 9 has a diameter of 54mm and the probe 10 has a diameter of 5 mm.
In order to improve the grouting efficiency and ensure the grouting effect, in step S6, the grouting pressure is 1.0-2.0 MPa.
In order to improve the grouting effect, the width of the fracture after the fracturing work in steps S4 and S5 is not less than 3 times the diameter of the slurry particles.
The method adopts a mode of advanced grouting of narrow coal pillars in the gob-side roadway, the grouting time is reasonably selected, before stoping on the working face of an upper section, the coal pillars are not influenced by mining, at the moment, drill holes are distributed in the coal pillars, cracks are caused by electric pulse shock waves, the porosity of coal bodies is increased, slurry can smoothly enter the cracks, the coal pillars are effectively reinforced by the grouting mode, and the bearing capacity and the stability of the coal pillars in the gob-side roadway are improved. The coal pillar is detected in the early stage, so that the compression deformation condition and the fracture development condition of the coal pillar can be analyzed, grouting can be directly performed on the part with larger fracture development, and the electric pulse cracking mode is adopted on the part with smaller fracture development, so that the porosity of the coal pillar is effectively increased, slurry can smoothly enter the fracture, and the grouting reinforcement of the coal pillar is completed; when the probe is adopted for detection, each test is carried out on a vertical plane, and the probe is provided with four mutually-perpendicular probes for detection, so that the test direction can be effectively fixed, and the detection precision is effectively improved. The coal body is fractured by electric impact to form a fracture surface, so that the fractures of smaller parts can be effectively filled in the fractures in the coal body, the porosity of the coal pillar can be effectively increased, the inside of the coal body can be fully grouted, and the grouting reinforcement effect can be obviously improved. The time of shock wave repeated operation is very short, enables to send and splits the operation and can accomplish fast, efficient, simultaneously, utilizes the shock wave to send and splits the coal body, can not cause secondary pollution, and the power disturbance is little, can not damage original strut, simultaneously, can not pollute the air in the pit, and the security is high. According to the invention, the grouting reinforcement operation is performed in advance on the area of the coal pillar which is not influenced by mining, so that the coal pillar is not influenced by the mining operation in the subsequent mining process, and the coal pillar can have stable pressure for bearing the top plate. The method has the advantages of simple step operation, low cost, safety, reliability, accurate detection, high fracturing speed, controllable fracture range, stable grouting reinforcement and the like, effectively ensures the safe and efficient production work of the coal mine, and has wide application prospect. The method is also suitable for the problem of insufficient grouting caused by small cracks of the coal rock mass.

Claims (7)

1. The method for reinforcing the narrow coal pillar along the hollow roadway through advanced grouting comprises a drilling penetration sounding instrument and an electric pulse device (4), wherein the drilling penetration sounding instrument comprises a conveying rod (8), a lifter (7), a probe (9), a probe (10), a hand pump (6) and a data acquisition instrument (12), the conveying rod (8) is a telescopic rod piece, one end of the conveying rod (8) is connected with the lifter (7), and the outer diameter of the conveying rod is smaller than the inner diameter of a drill hole (2) to be detected; the lifter (7) is arranged in the roadway (5) at the upper section, the lifter (7) is of a liftable structure, and the pitching angle can be adjusted, so that the depth of the conveying rod (8) entering the drill hole (2) can be adjusted, and the angle of the conveying rod (8) can be adjusted to adapt to the drill holes (2) at different angles; the probe (9) is arranged at the upper end of the conveying rod (8), four radial mounting holes (24) are uniformly formed in the top end of the probe, an oil duct (27) communicated with the inner ends of the four radial mounting holes (24) is further formed in the probe, and an oil inlet (24) of the oil duct (27) is formed in the surface of the probe (9); the number of the probes (10) is four, the four probes (10) are respectively installed in four radial installation holes (24), and the four probes are pairwise distributed in the x-axis direction and the y-axis direction; a piston ring (25) is installed on the outer side of the inner end of the probe (10) and is in sliding sealing fit with the radial mounting hole (24) through the piston ring (25), the length of the probe (10) is smaller than the depth of the radial mounting hole (24), and the inner end of the probe is connected with the bottom of the radial mounting hole (24) through a tension spring (26); the outer part of the top end of the probe (10) is arranged on the pressure sensor; a displacement sensor for detecting the extending length of the probe (10) is arranged on the probe (9); the hand pump (6) is arranged in the roadway (5) of the upper section and is connected with an oil inlet (24) on the probe (9) through an oil way (13); the data acquisition instrument (12) is connected with the displacement sensor and the pressure sensor through a cable (11);
the electric pulse device (4) comprises a push rod (18), an operating platform (16), a shock wave generator (17), a hole packer (19) and a controller (14), wherein one end of the push rod (18) is connected with the operating platform (16), and the outer diameter of the push rod is smaller than the inner diameter of the drill hole (2); the operating platform (16) is arranged in the roadway (5) of the upper section, and the operating platform (16) is used for controlling the adjustment of the telescopic length and the pitching angle of the push rod (18); the size of the shock wave generator (17) is smaller than the inner diameter of the drill hole (2), and the shock wave generator is arranged at the other end of the push rod (18); the hole packer (19) is of a cylindrical structure, is sleeved outside the push rod (18), is matched with the hole opening of the drill hole (2), and is used for establishing sealing connection between the push rod (18) and the hole opening of the drill hole (2); the hole packer (19) is provided with a water injection port (20) communicated with the inner cavity of the hole packer; the controller (14) is connected with the operating platform (16) and the shock wave generator (17);
the method is characterized by comprising the following steps;
s1: before stoping along the working face (22) of the upper section of the hollow roadway, when the coal pillars (1) are not influenced by mining, arranging a row of drill holes (2) at a certain interval along the extending direction of the coal pillars (1) on one side of the excavated upper section of the roadway (5), wherein the depth of each drill hole (2) is not more than the thickness of the reserved coal pillars (1);
s2: detecting the drill hole (2) by using a drill hole sounding instrument; the conveying rod (8) is placed into the drill hole (2) by adjusting the lifter (7), and the probe (9) is conveyed to a position to be measured in the drill hole (2); starting a hand pump (6) to work, supplying oil into the radial mounting hole (24) through an oil way (13) and an oil duct (27), wherein the oil simultaneously pushes four piston rings (25) to move outwards, further two probes (10) in the x-axis direction to respectively extend out along the positive direction and the negative direction of the x-axis simultaneously, and two probes (10) in the y-axis direction to respectively extend out along the positive direction and the negative direction of the y-axis simultaneously; after the probe (10) slowly extends out, the end part of the probe is gradually contacted with the coal body in the coal pillar (1) and is tightly pressed until the probe penetrates into the coal body; the data acquisition instrument (12) acquires signals in real time by using the pressure sensor and the displacement sensor, analyzes information data of pressure and displacement in the drill hole (2) according to the acquired signals, and records and stores the information data; the connection between the hand pump (6) and the oil circuit (13) is disconnected, the probe (10) retracts into the probe (9) under the action of the tension spring (26), and the conveying rod (8) is driven to retract by adjusting the lifter (7), so that the probe (9) retracts to the next detection depth; sequentially obtaining the compression conditions and displacement information data of deep rock strata (3) with different depths until the horizontal detection process of the whole borehole (2) is completed;
s3: the data acquisition instrument (12) analyzes the compression degrees of different depths of the coal pillar (1) and the development condition of cracks in the coal body according to the obtained information data of the pressure and the displacement in the drill hole (2), can directly perform grouting reinforcement operation on the part with larger cracks in the coal pillar (1), and sequentially performs steps S4 and S5 on the part with smaller cracks in the coal pillar (1);
s4: selecting a drill hole (2), carrying out fracturing operation on a small crack part of a coal pillar (1) by using an electric pulse device (4), controlling a push rod (18) to extend into the bottom of the small crack part or the small crack part in the drill hole (2) through an operation table (16), sealing the orifice of the drill hole (2) by using a hole packer (19), and carrying out water injection operation through a water path connected to a water injection port (20); after the drill hole (2) is filled with water, a power supply is switched on, the shock wave releases energy to the periphery in a circular diffusion mode through the circular shock wave generator (17), the shock wave energy releases a tearing effect on the coal pillar (1) at the moment, the diffused shock wave forms an electro-hydraulic effect by combining with the water in the drill hole (2), the tearing type damage degree of the coal pillar (1) is further increased, the cracks of the coal body are effectively increased, the shock operation is repeated by utilizing the shock wave, in the process, the water is continuously injected with low pressure through the water injection port (20) and keeps constant water pressure, the water enters the deep part of the coal body along the cracks generated by the shock wave, the shock wave can be further coupled into the coal body around the drill hole (2) by utilizing the water, the water can serve as a propagation medium of the shock wave and also can protect the shock wave generator (2), and the multiple shock operations are repeatedly carried out until the cracks of the coal body are enlarged to a designated range, completing the operation of the operation point, then retracting the push rod (18) to the part with smaller crack development, repeating the operation mode of the previous operation point, and sequentially operating to the position 0.3m away from the hole opening, namely completing the operation of one drilling hole (2); the controller (14) can obtain the real-time extension distance of the shock wave through the shock wave generator (17), further obtain the peripheral cracking range and display the peripheral cracking range on the display;
s5: observing the cracking range of the shock wave through a display connected to the controller (14), taking out the electric pulse device (4) after the expected effect is achieved, performing the impact operation of the next adjacent drill hole (2), repeating the operation of the step S4, judging whether the cracking range of the current drill hole (2) is communicated with the cracking range of the previous drill hole (2) or not according to the change condition of water pressure, completing the impact operation of the drill hole (2) when the two adjacent cracking ranges are communicated, and continuing the cracking operation of the next drill hole (2) until all the small-crack regions of the coal pillars (1) in the whole upper section roadway (5) are cracked, so that the undisturbed coal pillars (1) are cracked in advance before the recovery of the upper section working face (22);
s6: after the cracks of the small part of the coal pillar (1) are completely cracked, the cracks in the coal pillar (1) are increased to the size meeting the requirements, on the basis of the original anchor net support of the coal pillar (1), a grouting anchor rod (21) is placed in a drill hole (2) to perform grouting reinforcement on the interior of the coal pillar (1), a discharge hole (15) is formed in each of two sides of the length direction of the grouting anchor rod (21), a hole sealing ring is used for sealing the hole opening, grouting equipment is connected with the head end of the grouting anchor rod (21), grouting is performed on the deep part of the drill hole (2) by the aid of the grouting equipment, grout diffuses into the coal body along with the cracks to be cemented with the coal body to form a whole, the grouting operation is finished after the specified pressure range is reached, the pressure stabilization lasts for 10-15 min, and the grouting operation is stopped; and other drill holes (2) are sequentially grouted in the same grouting mode, so that coal bodies in the whole coal pillar (1) form a whole again, and the bearing capacity and stability of the coal pillar (1) are improved.
2. The method for reinforcing narrow coal pillars along a gob-side entry in advance by grouting according to claim 1, wherein in step S6, the number of the rows of drill holes (2) in the longitudinal direction is four, and the distance between two adjacent drill holes (2) is 800 mm; the distance between the rows of drill holes (2) in the longitudinal direction is 1000 mm; the aperture of the drilling hole (2) is 75mm, the diameter of the grouting anchor rod (21) is 28mm, and the length of the grouting anchor rod is smaller than the depth of the drilling hole (2).
3. The method for reinforcing narrow coal pillars of gob-side roadways by advanced grouting according to claim 1 or 2, characterized in that a tracer is added into the grouting material in step S6, so that the penetration range of slurry can be observed conveniently through the tracer.
4. The method for reinforcing the narrow coal pillar along the hollow roadway by means of advanced grouting according to claim 3, wherein single-liquid cement slurry is selected as a grouting material in step S6, and the water-cement mass ratio of the single-liquid cement slurry is 1: 0.75, and adding an additive in the stirring process; the admixture is 1: 6 mixture of water reducing agent and expanding agent, the slurry viscosity of the mixture is 33S, and the density of the mixture is 1.62G/CM3The calculus rate is 97%.
5. The method for reinforcing the narrow coal pillar along the gob-side entry by advanced grouting according to claim 4, wherein the diameter of the probe (9) is 54mm, and the diameter of the probe (10) is 5 mm.
6. The method for reinforcing the narrow coal pillar along the gob-side entry in advance by grouting according to claim 5, wherein in step S6, the grouting pressure is 1.0-2.0 MPa.
7. The method for reinforcing narrow coal pillars along gob sides by advanced grouting according to claim 6, wherein the width of the fractures after the fracturing operation in steps S4 and S5 is not less than 3 times the diameter of slurry particles.
CN202010863860.3A 2020-08-25 2020-08-25 Advanced grouting reinforcement method for narrow coal pillars of gob-side roadway Pending CN112096382A (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107701188A (en) * 2017-10-25 2018-02-16 太原理工大学 One kind cuts top destressing method for the mined out side static state spalling of gob side entry driving thin coal pillar
CN109162755A (en) * 2018-09-11 2019-01-08 中国矿业大学 A kind of coal uncovering method that electric pulse is combined with grouting and reinforcing
CN109707422A (en) * 2018-12-21 2019-05-03 河南理工大学 A kind of goaf roadway fender grouting method for protecting support
CN111022049A (en) * 2019-11-25 2020-04-17 中国矿业大学 Operation-controllable roof-cutting pressure-relief gob-side entry retaining method
CN111287770A (en) * 2020-03-05 2020-06-16 中煤能源研究院有限责任公司 Method for preventing coal wall caving by reinforcing coal body through microbial grouting
CN111365021A (en) * 2020-03-26 2020-07-03 中国矿业大学(北京) Pre-grouting solidification method for narrow coal pillars of fully mechanized caving coal roadway
CN111502662A (en) * 2020-04-28 2020-08-07 中煤能源研究院有限责任公司 Prevention and control method for deep pressure relief shallow part reinforcement of rock burst mine advanced coal body

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107701188A (en) * 2017-10-25 2018-02-16 太原理工大学 One kind cuts top destressing method for the mined out side static state spalling of gob side entry driving thin coal pillar
CN109162755A (en) * 2018-09-11 2019-01-08 中国矿业大学 A kind of coal uncovering method that electric pulse is combined with grouting and reinforcing
CN109707422A (en) * 2018-12-21 2019-05-03 河南理工大学 A kind of goaf roadway fender grouting method for protecting support
CN111022049A (en) * 2019-11-25 2020-04-17 中国矿业大学 Operation-controllable roof-cutting pressure-relief gob-side entry retaining method
CN111287770A (en) * 2020-03-05 2020-06-16 中煤能源研究院有限责任公司 Method for preventing coal wall caving by reinforcing coal body through microbial grouting
CN111365021A (en) * 2020-03-26 2020-07-03 中国矿业大学(北京) Pre-grouting solidification method for narrow coal pillars of fully mechanized caving coal roadway
CN111502662A (en) * 2020-04-28 2020-08-07 中煤能源研究院有限责任公司 Prevention and control method for deep pressure relief shallow part reinforcement of rock burst mine advanced coal body

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