CN111119926A - Gob-side entry retaining non-pillar mining support method for fully-mechanized coal mining face - Google Patents
Gob-side entry retaining non-pillar mining support method for fully-mechanized coal mining face Download PDFInfo
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- CN111119926A CN111119926A CN201911337585.5A CN201911337585A CN111119926A CN 111119926 A CN111119926 A CN 111119926A CN 201911337585 A CN201911337585 A CN 201911337585A CN 111119926 A CN111119926 A CN 111119926A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/006—Lining anchored in the rock
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D19/00—Provisional protective covers for working space
- E21D19/02—Provisional protective covers for working space for use in longwall working
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/003—Machines for drilling anchor holes and setting anchor bolts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/025—Grouting with organic components, e.g. resin
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0093—Accessories
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F15/00—Methods or devices for placing filling-up materials in underground workings
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F15/00—Methods or devices for placing filling-up materials in underground workings
- E21F15/02—Supporting means, e.g. shuttering, for filling-up materials
- E21F15/04—Stowing mats; Goaf wire netting; Partition walls
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F5/00—Means or methods for preventing, binding, depositing, or removing dust; Preventing explosions or fires
- E21F5/08—Rock dusting of mines; Depositing other protective substances
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D3/00—Particular applications of blasting techniques
Abstract
The invention relates to the technical field of coal mining support, in particular to a gob-side entry retaining pillar-free mining support method for a fully mechanized coal mining face; the method comprises the following steps: the method comprises the following steps of firstly, reinforcing and supporting a constant-resistance anchor cable, and secondly: and (3) top plate presplitting blasting drilling construction and top plate presplitting blasting construction, wherein the third step is as follows: and (5) retaining waste rock support after the frame, and the fourth step: spraying slurry; the coal-column-free working face adopts a supporting method taking 'roof cutting pressure relief + constant-resistance large-deformation anchor cable supporting' as a main body, the stress transmission of the working face top plate is cut off in a local range through presplitting joint-cutting blasting, the pressure of the roadway top plate is weakened, and the presplitting blasting can well protect the integrity of the roadway top plate; reinforcing and reinforcing are carried out by utilizing the constant-resistance large-deformation anchor cable, the top plate is controlled to sink, the reserved surrounding rock of the roadway can play a self-bearing role to the maximum extent, the deformation of the roadway is reduced, and the roadway reserving effect is ensured.
Description
Technical Field
The invention relates to the technical field of coal mining support, in particular to a gob-side entry retaining pillar-free mining support method for a fully mechanized coal mining face.
Background
At present, most mines in China enter a deep mining stage, and the main difficulties in carrying out deep mining work of coal mines are pressure rise around a coal mine tunnel, softening of the whole condition of surrounding rocks, high deformation rate around the coal mine tunnel, high difficulty in later maintenance work and the like. The method of using the remaining coal pillars continuously along the supporting mode of the two ends of the empty stope face maintains the overall quality of the roadway by using the coal pillars, and certain influence is formed on the coal mining efficiency and the resource development rate, and the method is not an optimal measure. Under the normal condition, the coal resources of the part account for about 40 percent of the whole development resources, so that the research on the non-pillar gob-side entry retaining construction technology of the fully-mechanized coal mining face in the deep well mining work is of great importance, the development total amount of coal mine resources in China can be greatly improved, and meanwhile, the working efficiency of coal mining can also be improved. And then, in the process of advancing the working face of the gob-side entry retaining coal pillar-free mining of the fully mechanized mining working face, the retained roadway is influenced by dynamic pressure, and corresponding support measures need to be taken for the retained roadway.
Disclosure of Invention
The invention provides a fully mechanized coal mining face gob-side entry retaining pillar-free mining support method, which aims to solve the technical problems that a fully mechanized coal mining face gob-side entry retaining pillar-free mining is not adopted, a retained roadway is influenced by dynamic pressure, the roadway is easy to deform and the like.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a fully mechanized coal mining face gob-side entry retaining coal pillar-free mining support method comprises the following steps:
firstly, reinforcing support by using a constant-resistance anchor cable, constructing a constant-resistance large-deformation anchor cable to reinforce a roadway, and adding a W steel strip to the constant-resistance anchor cable on a joint cutting side along the direction of the roadway;
the second step is that: the method comprises the following steps of (1) top plate pre-splitting blasting drilling construction and top plate pre-splitting blasting construction, wherein before working face extraction, a cutting roadway working face support is lowered, an original anchor rod/cable is subjected to rod/cable withdrawal treatment, blasting pre-splitting joint cutting is carried out on a cutting hole position under the condition that constant-resistance large-deformation anchor cable reinforcement is carried out before and after the cutting hole position is guaranteed to be more than or equal to 10m, so that a top plate near the cutting hole can completely stride, and a reliable new side part is formed; under the premise of ensuring that the advance reinforcement of the constant-resistance large-deformation anchor cable is more than or equal to 20m, blasting pre-splitting cutting is carried out on a return airway of a working face according to the advancing direction of the working face to form a top-cutting pressure-relief pre-splitting cutting line, and blasting pre-splitting cutting is completed on the whole airway at one time;
the third step: after the working face is pushed, performing waste rock blocking support behind the end bracket in time, and performing support according to a single-prop support scheme, wherein the arrangement distance of the waste railways at the side close to the mining area is 500 mm;
the fourth step: and (3) guniting, after the roof collapses and is stable, filling the place with insufficient collapse after the roadway is stable, removing the single prop, shaping and maintaining the roadway according to the mine pressure observation condition, and timely guniting and sealing when the coal seam has spontaneous combustion danger so as to meet the use requirement.
① calibrating the position of an anchor bolt hole, marking the installation position of the anchor bolt according to the design requirement according to the measured central line of the roadway;
② preparing tools, transporting the drilling machine, the drill rod, the blowpipe, the air and water pipe, the pickaxe and the shovel to a construction site, and placing the tools in order close to one side of the roadway after the drilling machine is connected with the air and water pipeline;
③ the anchor cable machine is adjusted by constructors, the spot eyer assists the anchor rod machine operator to support the drilling tool when drilling, the drill bit is aligned with the eye socket and is tightly pressed, then the spot eyer is withdrawn to the rear part of the anchor rod machine operator to be responsible for observation, the anchor rod machine operator slowly starts the drilling tool to drill, the diameter of the drill bit is 32mm, the air quantity is increased to drill after drilling for 30-50 mm, the air quantity is reduced to enable the drilling tool to run at low speed after reaching the design depth, the air and water are shut off after slowly withdrawing the drill rod, and the drilling tool is stopped to run;
④, replacing an MS-SPD45/85 type constant resistor installation hole guide reaming bit with the diameter of 85mm, and reaming the surface of a drilled hole along the drilling guide of the anchor cable, wherein the reaming depth is 500 mm;
⑤, loading 3 MSK2360 type resin anchoring agents into the anchor cable eye one by one, and then slightly ejecting the anchoring agents into the bottom of the anchor cable eye by using steel stranded wires with the diameter of 21.8mm and the length of 7500 mm;
⑥ starting the anchor cable drilling machine to rotate and push until the designed depth is reached, stopping stirring after the stirring time is 15-20 s, and withdrawing the drilling machine after waiting for 2-3 min (the specific stirring time and the solidification time are subject to the number of the actually used anchoring agent formulation), wherein the constant-resistance anchor cable is exposed for 180-300 mm;
⑦ installing anchor cable trays with the specification of 300mm multiplied by 12mm and the diameter of the anchor cable holes of 100 mm;
⑧ a constant resistor with specification of HZS35-300-0.5 and diameter of 79mm is installed;
⑨ installing lock, and applying pretightening force with TQ22-500/63 type cable tensioner, the pretightening force is not less than 25 t.
①, accurately marking the positions of all the drill holes along the top plate of the roadway on the coal mining side by taking the central line of the roadway as a reference according to design requirements, wherein the surfaces of the drill holes are arranged on a straight line, and the drill hole spacing is 400 mm;
② adjusting the position of the drilling machine to make the drill arm of the drilling machine, i.e. the drill rod, form 75 degrees with the horizontal plane in three-dimensional space and be vertical to the connecting line of the drilling holes;
③ using a special drill bit with a diameter of 48mm, accurately positioning the drilling mark position on the roadway roof according to the above angle, performing drilling construction to reach the designed cutting depth, and accurately operating the drilling machine to ensure the flatness of the formed hole;
① installing BTC-1500 type energy-gathering pipe in the blasting drilling hole with outer diameter 42mm, inner diameter 36.5mm and pipe length 1500mm, poking the energy-gathering pipe to the hole bottom;
② placing coal mine three-stage emulsion explosive in energy-gathering pipes, wherein each hole has an outer diameter of phi 28mm and a length of 200mm, before charging, each energy-gathering blast hole is continuously charged from a hole bottom energy-gathering pipe in a roadway according to blasting charge design parameters, arranging a detonator and a lead, penetrating the lead through a second energy-gathering pipe, connecting the second energy-gathering pipe with a special connecting piece for a first energy-gathering pipe, continuously charging in the second energy-gathering pipe, arranging the lead, repeating the method, and sequentially completing charging of all energy-gathering pipes, wherein each energy-gathering pipe is provided with a detonator;
③ sealing the hole with stemming, the sealing length is not less than 1500 mm;
④ setting safe blasting distance and organizing blasting work;
⑤ the explosion effect is monitored and analyzed in time after explosion, and the crack rate of the top plate is ensured to be more than 75%.
Further, a third step of after-frame waste rock blocking support is that a combined waste rock blocking support mode consisting of a waste railway, a single hydraulic prop and a reinforcing mesh is adopted within 200m behind a ① working face support;
② waste railway and single hydraulic prop are arranged at intervals of 500mm, the waste railway is fixed by wood wedges, the single hydraulic prop and the waste railway are arranged at intervals and are on the same straight line, the interval of the single hydraulic prop at the gangue blocking side is 500mm, the reinforcing mesh adopts a reinforcing steel bar welding mesh with the diameter of 6.5mm, the reinforcing mesh and the waste railway and the single hydraulic prop are bundled together, the reinforcing mesh and the reinforcing mesh are overlapped by no less than 100mm and are bundled by iron wires, when the gangue blocking single support reaches 200m, three liquid discharge hydraulic props are removed, the removed members are moved to the forefront of the support section behind the support, and the waste gangue blocking structure is formed by remounting, meanwhile, other support structures of the railway, the gangue blocking single hydraulic prop, the reinforcing mesh and the like are kept unchanged within the range of 200m after the support;
③ spreading air duct cloth between the reinforcing mesh and the retractable U-shaped steel support, the height is 3.3m, the upper and lower parts exceed 30cm, the excessive parts are fixed to the top bottom plate respectively, and the air duct cloth is effectively sealed, the width of the lap joint of the air duct cloth is 30cm, and sealing treatment is also performed after fixation.
Compared with the prior art, the invention has the following beneficial effects:
the coal-column-free working face adopts a supporting method taking 'roof cutting pressure relief + constant-resistance large-deformation anchor cable supporting' as a main body, the stress transmission of the working face top plate is cut off in a local range through presplitting joint-cutting blasting, the pressure of the roadway top plate is weakened, and the presplitting blasting can well protect the integrity of the roadway top plate. Reinforcing and reinforcing are carried out by utilizing the constant-resistance large-deformation anchor cable, the top plate is controlled to sink, the reserved surrounding rock of the roadway can play a self-bearing role to the maximum extent, the deformation of the roadway is reduced, and the roadway reserving effect is ensured.
Detailed Description
The present invention is further illustrated by the following specific examples.
Example 1
In this embodiment, the mine of the Jinhuagong mine from the GmbH company of Daqigong coal mine is taken as an example:
jinhuagong mine nan shan 7-4#The layer 402 panel 8209 working face is a working face using a top-cutting pressure relief automatic roadway coal pillar-free mining technology. In the process of propelling the working face, the reserved roadway is influenced by dynamic pressure, and corresponding support measures need to be taken for the reserved roadway. The concrete supporting steps are as follows:
south mountain 7-4#Layer 402 panel 8209 working face return airway constant resistance anchor rope reinforcement and roof cutting off press overall work progress as follows:
the first step is as follows: and (4) reinforcing and supporting the constant-resistance anchor cable. And constructing a constant-resistance large-deformation anchor cable reinforcing roadway according to the designed supporting parameters, and adding a W steel strip to the constant-resistance anchor cable on the joint cutting side along the roadway direction to improve the overall supporting performance.
The installation process of the constant-resistance large-deformation anchor cable comprises the following steps:
firstly, strictly checking the section specification of the roadway according to the middle and waist lines, and firstly processing when the section specification does not meet the requirements of operation regulations; before drilling, the upper and the roof are knocked first, the surrounding rock condition of the top wall is carefully checked, the live waste rock and the dangerous rock are knocked off, the anchor cable can start to work after safety is confirmed, the position of the anchor cable is accurate, the eye position error is not more than 200mm when no original support is obstructed, and the eye direction error is not more than 2 degrees.
Before the constant-resistance anchor cables are installed in batches, an anchoring force test is carried out, the anchoring force of the constant-resistance anchor cables must be ensured to be not less than 420KN (42t), and otherwise, the using effect is influenced.
The construction process comprises the following steps: the method comprises the steps of top knocking, hole positioning → drilling tool → point anchor eye → expanding constant resistance device mounting hole → installing anchor agent, steel strand → fully stirring anchor agent anchor cable → installing steel belt → installing anchor cable tray → installing constant resistance device → installing lock → applying pretightening force → cleaning the site.
①, calibrating the position of the anchor bolt hole, namely calibrating the installation position of the anchor cable according to the design requirement according to the measured and given roadway center line.
② preparing tools, transporting the drilling machine, drill pipe, blow pipe, wind and water pipe, pickaxe, shovel, etc. to the construction site, putting the drilling machine in order near one side of the roadway after the drilling machine is connected with the wind and water pipe, and the tools must be intact and can be used normally.
③ the anchor cable machine is adjusted by the constructor, the pilot eye assists the anchor rod machine operator to support the drilling tool when drilling, the drill bit is aligned with the eye socket and is pushed tightly, then the pilot eye is withdrawn to the rear part of the anchor rod machine operator to observe, the anchor rod machine operator slowly starts the drilling tool to drill, the diameter of the drill bit is 32mm, the air volume is increased to drill after drilling for 30-50 mm, the air volume is reduced to enable the drilling tool to run at low speed after reaching the designed depth, the air and water are shut off after slowly withdrawing the drill rod, and the operation of the drilling tool is stopped.
④, replacing MS-SPD45/85 type constant resistor installation hole guiding reaming bit, the diameter is 85mm, reaming is carried out on the surface of the drilled hole along the drilling guiding of the anchor cable, and the reaming depth is 500 mm.
⑤ 3 MSK2360 type resin anchoring agents were loaded into the anchor cable eye one by one, and then the anchoring agents were gently pushed into the bottom of the hole by steel strands 21.8mm in diameter and 7500mm in length.
⑥ starting the anchor cable drilling machine to rotate and push until reaching the designed depth, stopping stirring after stirring for 15-20 s, and withdrawing the drilling machine after waiting for 2-3 min (the specific stirring time and the solidification time are subject to the actual anchoring agent type number).
⑦ an anchor cable tray is installed, the specification is 300mm multiplied by 12mm, and the diameter of the anchor cable hole is 100 mm.
⑧ is provided with a constant resistor with specification of HZS35-300-0.5 and diameter of 79 mm.
⑨ installing lock, and applying pretightening force with TQ22-500/63 type cable tensioner, the pretightening force is not less than 25 t.
The second step is that: and (4) top plate presplitting blasting drilling construction and top plate presplitting blasting construction. Before the working face is mined, the cutting roadway working face support is lowered, the original anchor rod (cable) is retreated, the constant-resistance large-deformation anchor cable is reinforced before and after the position of the cut hole is guaranteed to be larger than or equal to 10m, the position of the cut hole is blasted and presplitting cut is conducted, so that the top plate near the cut hole can completely stride, and a reliable new side portion is formed. On the premise of ensuring that the advance reinforcement of the constant-resistance large-deformation anchor cable is more than or equal to 20m, according to the advancing direction of a working surface, the south mountain 7 is subjected to-4#Blasting pre-splitting joint cutting is carried out on the return air roadway of the working face of the layer 402 disc area 8209 to form a top cutting and pressure relief pre-splitting joint cutting line, and blasting pre-splitting joint cutting is completed on the whole roadway at one time;
the construction of a joint cutting procedure is carried out by using a DCA-45 type top plate presplitting blasting construction drilling machine which is specially designed, and the construction mainly comprises the following steps:
① according to the design requirement, with the roadway center line as the benchmark, accurately marking each drilling position along the coal mining side roadway roof, the drilling surface is arranged on a straight line, the drilling distance is 400 mm.
② the position of the drill is adjusted so that the drill boom (i.e., the drill pipe) of the drill is 75 deg. in three dimensions from the horizontal and perpendicular to the line of the drill holes.
③ use the special drill bit that the diameter is 48mm, according to above-mentioned angle, at tunnel roof drilling mark position pinpoint to go into the construction and reach the design lancing degree of depth, the accurate operation rig guarantees the pore-forming straightness.
The top plate presplitting joint cutting blasting construction steps are as follows:
the top plate presplitting kerf blasting method adopts a patented energy-gathering tension kerf blasting method, single-hole and multi-hole connected blasting is carried out to carry out presplitting blasting test construction on the top plate according to design requirements, the top plate presplitting blasting construction is carried out according to optimal parameters provided by the connected blasting test, and the specific process flow is as follows:
① BTC-1500 type energy-gathering pipe is installed in the blasting drill hole after construction, the outer diameter is 42mm, the inner diameter is 36.5mm, the pipe length is 1500mm, and the energy-gathering pipe is poked to the hole bottom.
② the coal mine three-stage emulsion explosive is placed in the energy-gathering pipe, each hole has 2 coils, the external diameter of explosive package phi 28mm and the length of explosive package phi 200mm, the explosive and detonator are provided freely by the mine, before charging, each energy-gathering blast hole is charged continuously from the hole bottom energy-gathering pipe in the tunnel according to the blasting charge design parameters, and is provided with detonator and lead wire, then the lead wire is passed through the second energy-gathering pipe, and is connected with the first energy-gathering pipe by special connecting piece, then the second energy-gathering pipe is charged continuously and is provided with lead wire, the above method is repeated, all the energy-gathering pipe charges are completed in turn, and each energy-gathering pipe is provided with a detonator.
③ sealing the hole with stemming, the sealing length is not less than 1500 mm.
④ setting safe blasting distance according to the rules of coal mine safe construction operation and organizing blasting work.
⑤, monitoring and analyzing the blasting effect in time by organization personnel of a design party after blasting to ensure that the crack rate of the top plate is over 75 percent, and the specific evaluation method comprises the following steps:
and numbering each blast hole, evaluating and counting the blast hole cracks of each blast hole after pre-splitting blasting joint cutting, and establishing a blast hole counting file.
1) Detection method
And detecting surface cracks and in-hole cracks of the blast hole by adopting a method of combining surface detection and in-hole detection.
2) Detection instrument and apparatus
① the explosion-proof camera takes pictures of the roadway surface and detects the communication condition of the directional pre-crack surface.
② automatic imager for drilling hole, detecting and imaging the inside of the drilling hole, and detecting the expansion condition in the directional pre-crack hole.
3) Detection procedure and evaluation index
① the first step, after hole forming, before presplitting blasting, the holes are numbered, and the automatic imaging instrument of the holes detects the hole forming effect and the crack condition.
The angle error rate is that K1 is equal to (α design- α actual)/α design is less than or equal to 10 percent
Drilling hole straightness: k2 ═ L pothole/L drilled hole ≤ 10%
② taking pictures on the surface of the tunnel with explosion-proof camera, and detecting the communication condition of the crack surface.
Surface crack rate: the K3-L surface crack/L hole spacing is more than or equal to 90 percent
③ and thirdly, detecting the inside of the automatic imaging instrument of the drilling hole and detecting the expansion condition in the directional pre-crack hole.
The rate of cracks in the pores: k4 ═ L in-hole crack/L drilled hole is more than or equal to 75%
④ the fourth step, evaluating the effect of lane formation and collapsing the half-eye rate.
Half-eye ratio: k5 ≥ N half-hole rate/N hole rate ≥ 85%
⑤ fifth step, close critical distance assessment, distance after shelf to complete collapse.
Distance from after shelf to complete collapse: k6 is less than or equal to 20m
⑥ sixth step, bracket stress concentration factor evaluation.
Stress concentration coefficient of the bracket: k7 is equal to or less than 1 when P top plate breaking limit force/P normal force
The third step: and (5) blocking waste rock for supporting after the frame. After the working face is pushed, waste rock blocking support is timely carried out behind the end bracket, support is carried out according to a single-prop support scheme, the arrangement distance of the waste railways close to the goaf side is 500mm, and the waste railways need to be fastened by using wood wedges when being arranged; in order to prevent air leakage, air duct cloth can be laid between the reinforcing mesh and the waste railway, the height is 3.3m, the upper part and the lower part of the air duct cloth respectively exceed 30cm, and the exceeding parts are respectively fixed on the top bottom plate and are effectively sealed. The width of the lap seam of the air duct cloth is 30cm, and sealing treatment is also carried out after fixation.
Roadway reinforcement and waste rock blocking measures in the range of 0-200 m behind the roadway section frame of the 7-4# layer 402 disk area 8209 working surface of the south mountain:
① in order to prevent the roof from falling rocks and rushing into the roadway during the period of pressure coming, a combined waste rock retaining and supporting mode consisting of waste railways, single hydraulic props and reinforcing meshes is adopted within the range of 200m behind the working face support.
② waste railway and single hydraulic prop are arranged at intervals of 500mm, the waste railway is fixed by wood wedges, the single hydraulic prop and the waste railway are arranged at intervals and are on the same straight line, the interval of the single hydraulic prop at the gangue blocking side is 500mm, the reinforcing mesh is a reinforcing welded mesh with the diameter of 6.5mm, the reinforcing mesh and the waste railway and the single hydraulic prop are bundled together, the reinforcing mesh and the reinforcing mesh are overlapped for not less than 100mm, and the reinforcing mesh is bundled by iron wires, when the gangue blocking single support reaches 200m, three liquid discharge hydraulic props close to 8207 side are removed, the removed members are moved to the forefront of the support section at the back of the support, and the gangue blocking structure is assembled again, meanwhile, other support structures of the waste railway, the gangue blocking single hydraulic prop, the reinforcing mesh and the like are kept unchanged within 200m after the support.
③ in order to prevent air leakage, laying air duct cloth between the reinforcing mesh and the retractable U-shaped steel support, with a height of 3.3m, a height of 30cm above and below, and a top bottom plate respectively, and sealing effectively, wherein the width of the lap seam of the air duct cloth is 30cm, and sealing is performed after fixation.
④ the tunnel is stable the back, fills the insufficient place of caving, removes the monomer pillar, observes the condition according to the ore deposit pressure and carries out treatments such as plastic, maintenance to the tunnel, in time carries out the whitewashing when the coal seam has spontaneous combustion danger and seals, satisfies the operation requirement, waits that next working face uses.
The fourth step: and (6) spraying slurry. And after the top plate collapses and is stable, filling the place with insufficient collapse, finishing the shape of the roadway to meet the use requirement, and carrying out guniting work when needed to ensure the stability of the roadway.
In the steps, (1) the length design method of the constant-resistance large-deformation anchor cable comprises the following steps:
in order to ensure the stability of the roadway during the roof cutting process and the period of coming pressure, the roadway roof is reinforced and reinforced by adopting a constant-resistance large-deformation anchor cable before presplitting and roof cutting. The length of the constant-resistance anchor cable can be calculated according to an empirical formula:
Lconstant temperature＝HSeam+(1.5～2.5)
In the formula: l isConstant temperature: length of constant-resistance anchor cable, m; hSeam: kerf depth, m.
Namely, the length of the constant-resistance anchor cable is usually 1.5-2.5m longer than the depth of the cutting seam, the depth of the basic cutting seam is calculated to be 5m, and therefore the length of the medium-resistance anchor cable is 7.5 m.
(2) Designing the row spacing between the constant-resistance large-deformation anchor cables:
based on the roof-cutting short-wall beam theory and the mechanical model, the maximum shear stress of the joint surface can be calculated, namely the ultimate bearing capacity Pn of the anchor cable:
in the formula P0When the distance between the constant-resistance anchor cables on the joint cutting side is 1m, the section modulus W of the top plate and the rotational inertia J of the top plate rock mass are substituted into the calculation, and the bearing capacity of the constant-resistance anchor cable meets the requirement of Pn.
Therefore, in the embodiment, the constant-resistance large-deformation anchor cable is arranged in the direction perpendicular to the top plate, and 2 rows are arranged on the original supporting foundation:
the first row of constant-resistance anchor cables are designed to be 500mm away from the original roadway side, and the row spacing is 1000 mm;
the second row of constant-resistance anchor cables are positioned on the center line of the top plate of the roadway, and the row spacing is 2000 mm.
In addition, in consideration of joint cutting parameters and an original roadway design supporting mode, the diameter of a constant-resistance large-deformation anchor cable is 21.8mm, the length is 7500mm, the length of a constant-resistance device is 500mm, the outer diameter is 79mm, the maximum allowable deformation is 350mm, the constant-resistance value is 30 +/-2 t, the pre-tightening force is not less than 25t, the specification of a tray is 300mm multiplied by 12mm, and the diameter of a middle reaming hole is 100mm +/-1 mm
7-4#The layer 402 panel 8209 coal-column-free working face adopts a design scheme taking 'roof cutting pressure relief + constant-resistance large-deformation anchor cable support' as a main body, and through presplitting kerf blasting, roof stress transmission of the working face is cut off in a local range, the pressure of a roadway roof is weakened, and presplitting blasting can well protect the integrity of the roadway roof. Reinforcing and reinforcing are carried out by utilizing the constant-resistance large-deformation anchor cable, the top plate is controlled to sink, the reserved surrounding rock of the roadway can play a self-bearing role to the maximum extent, the deformation of the roadway is reduced, and the roadway reserving effect is ensured.
The method is practically applied to Jinhuagong mine Nanshan 7-4#In the production work of the working face of the layer 402 panel 8209, the cost investment caused by lane driving is greatly reduced, the time spent in lane driving is shortened, the normal replacement of the working face is ensured, and great economic benefits are created. A good precedent is developed for the gob-side entry retaining non-pillar mining of the fully mechanized coal mining face in the future and a good demonstration effect is played.
Claims (4)
1. A fully mechanized coal mining face gob-side entry retaining coal pillar-free mining support method is characterized by comprising the following steps:
firstly, reinforcing support by using a constant-resistance anchor cable, constructing a constant-resistance large-deformation anchor cable to reinforce a roadway, and adding a W steel strip to the constant-resistance anchor cable on a joint cutting side along the direction of the roadway;
the second step is that: the method comprises the following steps of (1) carrying out top plate presplitting blasting drilling construction and top plate presplitting blasting construction, before stoping of a working face, lowering a cutting roadway working face support, carrying out rod/cable withdrawing treatment on an original anchor rod/cable, carrying out blasting presplitting joint cutting on a cutting hole position under the condition that constant-resistance large-deformation anchor cable reinforcement is carried out before and after the cutting hole position is guaranteed to be more than or equal to 10m, and enabling a top plate near the cutting hole to stride down to form a new side part; under the premise of ensuring that the advance reinforcement of the constant-resistance large-deformation anchor cable is more than or equal to 20m, blasting pre-splitting cutting is carried out on a return airway of a working face according to the advancing direction of the working face to form a top-cutting pressure-relief pre-splitting cutting line, and blasting pre-splitting cutting is completed on the whole airway at one time;
the third step: after the working face is pushed, performing waste rock blocking support behind the end bracket in time, and adopting single pillars for supporting, wherein the arrangement distance of the waste railways at the side close to the goaf is 500 mm;
the fourth step: and (3) guniting, after the roof collapses and is stable, filling the place with insufficient collapse after the roadway is stable, removing the single prop, shaping and maintaining the roadway according to the mine pressure observation condition, and timely guniting and sealing when the coal seam has spontaneous combustion danger so as to meet the use requirement.
2. The fully mechanized coal mining face gob-side entry retaining coal pillar-free mining support method according to claim 1, wherein in the first step, the concrete construction steps of constant-resistance anchor rope reinforcement support are ① calibrating anchor bolt eye position, marking anchor rope installation position according to design requirements according to the measured given roadway center line;
② preparing tools, transporting the drilling machine, the drill rod, the blowpipe, the air and water pipe, the pickaxe and the shovel to a construction site, and placing the tools in order close to one side of the roadway after the drilling machine is connected with the air and water pipeline;
③ the anchor cable machine is adjusted by constructor, the drilling tool is supported by the eye-drop worker to assist the anchor rod machine operator when drilling, the drill bit is aligned with the eye socket and is tightly pressed, then the eye-drop worker is removed to the rear part of the anchor rod machine operator to take charge of observation, the anchor rod machine operator starts the drilling tool to drill, the diameter of the drill bit is 32mm, the air quantity is increased to drill after drilling for 30-50 mm, the air quantity is reduced to enable the drilling tool to run at low speed after reaching the designed depth, the air and water are shut off after withdrawing the drill rod, and the drilling tool is stopped to run;
④, replacing an MS-SPD45/85 type constant resistor installation hole guide reaming bit with the diameter of 85mm, and reaming the surface of a drilled hole along the drilling guide of the anchor cable, wherein the reaming depth is 500 mm;
⑤, loading 3 MSK2360 type resin anchoring agents into the anchor cable eye one by one, and then slightly ejecting the anchoring agents into the bottom of the anchor cable eye by using steel stranded wires with the diameter of 21.8mm and the length of 7500 mm;
⑥ starting the anchor cable drilling machine to rotate and push at the same time until the designed depth is reached, stopping stirring after the stirring time is 15-20 s, and removing the drilling machine after waiting for 2-3 min, wherein the constant-resistance anchor cable is exposed for 180-300 mm;
⑦ installing anchor cable trays with the specification of 300mm multiplied by 12mm and the diameter of the anchor cable holes of 100 mm;
⑧ a constant resistor with specification of HZS35-300-0.5 and diameter of 79mm is installed;
⑨ installing lock, and applying pretightening force with TQ22-500/63 type cable tensioner, the pretightening force is not less than 25 t.
3. The fully mechanized coal mining face gob-side entry retaining coal pillar-free mining support method according to claim 1, characterized in that the concrete construction steps of roof pre-splitting blasting drilling are ①, accurately marking the positions of all the drilling holes along the roof of the coal mining side roadway based on the central line of the roadway according to the design requirements, wherein the surfaces of the drilling holes are arranged on a straight line, and the spacing between the drilling holes is 400 mm;
② adjusting the position of the drilling machine to make the drill arm of the drilling machine, i.e. the drill rod, form 75 degrees with the horizontal plane in three-dimensional space and be vertical to the connecting line of the drilling holes;
③ using a special drill bit with a diameter of 48mm, accurately positioning the drilling mark position on the roadway roof according to the above angle, performing drilling construction to reach the designed cutting depth, and accurately operating the drilling machine to ensure the flatness of the formed hole;
① installing BTC-1500 type energy-gathering pipe in the blasting drilling hole with outer diameter 42mm, inner diameter 36.5mm and pipe length 1500mm, poking the energy-gathering pipe to the hole bottom;
② placing coal mine three-stage emulsion explosive in energy-gathering pipes, wherein each hole has an outer diameter of phi 28mm and a length of 200mm, before charging, each energy-gathering blast hole is continuously charged from a hole bottom energy-gathering pipe in a roadway according to blasting charge design parameters, arranging a detonator and a lead, penetrating the lead through a second energy-gathering pipe, connecting the second energy-gathering pipe with a special connecting piece for a first energy-gathering pipe, continuously charging in the second energy-gathering pipe, arranging the lead, repeating the method, and sequentially completing charging of all energy-gathering pipes, wherein each energy-gathering pipe is provided with a detonator;
③ sealing the hole with stemming, the sealing length is not less than 1500 mm;
④ setting safe blasting distance and organizing blasting work;
⑤ the explosion effect is monitored and analyzed in time after explosion, and the crack rate of the top plate is ensured to be more than 75%.
4. The fully mechanized coal mining face gob-side entry retaining coal pillar-free mining support method according to claim 1, wherein the third step is a waste rock retaining support method in which a combined waste rock retaining support form composed of a waste railway, a single hydraulic prop and a steel mesh is adopted within 200m behind ① face supports;
② waste railway and single hydraulic prop are arranged at intervals of 500mm, the waste railway is fixed by wood wedges, the single hydraulic prop and the waste railway are arranged at intervals and are on the same straight line, the interval of the single hydraulic prop at the gangue blocking side is 500mm, the reinforcing mesh adopts a reinforcing steel bar welding mesh with the diameter of 6.5mm, the reinforcing mesh and the waste railway and the single hydraulic prop are bundled together, the reinforcing mesh and the reinforcing mesh are overlapped by no less than 100mm and are bundled by iron wires, when the gangue blocking single support reaches 200m, the hydraulic prop is removed, the removed member is moved to the forefront of the support section behind the support, and the gangue blocking structure is re-installed, meanwhile, the support structures of the waste railway, the gangue blocking single hydraulic prop and the reinforcing mesh are kept unchanged within the range of 200m after the support;
③ spreading air duct cloth between the reinforcing mesh and the retractable U-shaped steel support, the height is 3.3m, the upper and lower parts exceed 30cm, the excessive parts are fixed to the top bottom plate respectively, and the air duct cloth is effectively sealed, the width of the lap joint of the air duct cloth is 30cm, and sealing treatment is also performed after fixation.
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