CN110656962A

CN110656962A - Large-inclination fully-mechanized caving mining coal caving method

Info

Publication number: CN110656962A
Application number: CN201910826060.1A
Authority: CN
Inventors: 王远德; 崔靖; 贾湛永; 高艳明; 李勇; 杨云刚; 王亚飞; 闫树勇; 孙江涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2020-01-07

Abstract

The invention discloses a large-inclination-angle fully-mechanized caving mining caving method which comprises large-inclination-angle fully-mechanized caving mining top coal caving performance evaluation, a control method of large-inclination-angle working face fully-mechanized caving mining stability, determination of large-inclination-angle fully-mechanized caving mining reasonable caving pace and determination of large-inclination-angle fully-mechanized caving mining reasonable caving mode. The invention solves the problems that the coal is discharged by the lower bracket and the coal on the top of the upper bracket flows empty in the coal discharging process of the area with large inclination angle, so that the serious potential safety hazard exists, and the coal resources are seriously wasted due to the fact that the coal is discharged by the lower bracket in a small amount to control the coal on the top of the upper bracket to flow empty; the coal caving efficiency and the coal recovery rate of the fully mechanized caving face are improved, and the dilution rate is reduced; the improvement of the cycle yield of the fully mechanized caving face is achieved.

Description

Large-inclination fully-mechanized caving mining coal caving method

Technical Field

The invention belongs to the technical field of underground coal mining, and particularly relates to a large-inclination fully-mechanized caving mining coal caving method. The method is particularly suitable for fully mechanized caving mining of soft and thick coal seams with large inclination angles.

Background

Mining practices show that the problems of serious potential safety hazards of coal caving of the lower support in an area with a large inclination angle and coal emptying of the top of the upper support in the mining process of a large-inclination-angle soft and thick coal seam, low cyclic output and coal caving efficiency, unreasonable advanced support mode and range, equipment gliding and dumping, gangue flying of a face scraper conveyor and the like exist. The coal seam with large inclination angle is a part of inclined and steeply inclined coal seams, and is a coal seam with special burying conditions and a coal seam which is recognized as difficult to mine by the international mining community. The variable-angle fully-mechanized coal mining working face of the large-inclination angle coal seam is influenced by the inclination angle of the coal seam and the angle change of the working face, the deformation and the damage of coal walls in different areas of the working face, the stress distribution and the mutual relation of supports are complex, and the safe and efficient mining cannot be guaranteed. After the large-dip-angle fully mechanized caving face is excavated, one side of the coal wall is a free area, and the coal wall is in a two-way or one-way stress state. The soft coal body of the coal wall generates plastic damage under the action of mine pressure, and the phenomena of rib spalling and roof collapse are easy to occur. The rib caving and roof caving can influence the supporting effect of the coal wall on the coal and rock mass on the working face, and influence the interaction relation between the working face bracket and the surrounding rock, which can further aggravate rib caving and roof caving and generate adverse effect on the control of the stope roof. In addition, too soft coal seam easily causes the caving of the working face, resulting in difficult control of the top plate. Because the coal seam is directly contacted above the support for the top coal mining and has plasticity, particularly when the coal seam is soft, the pressure of the top plate can be transmitted to the working face support through the coal seam. On one hand, due to the existence of the coal bed, the pressure of the working face support is relatively small, but the reaction force of the working face support to the top plate is also reduced, so that the top cutting effect to the top plate is poor, the top plate is not easy to collapse, when the top plate is not very hard, the problem is not very outstanding, but measures are required to be taken to ensure that the top plate can collapse in time if the top plate is hard; on the other hand, because the coal seam bears the pressure of the top plate, the coal seam becomes more broken, if measures are improper, the top coal above the support is caused to be emptied, the support empty roof phenomenon occurs, and potential safety hazards are caused.

For caving coal mining, a 'support-top coal-top plate' structure is arranged above a working face, the stress condition of the top plate can be influenced by the amount, position and speed of top coal discharging, and the support effect of the support can be influenced naturally, namely the stability of a 'support-top coal-top plate' structure system is influenced. Therefore, the coal caving step pitch influences the coal caving quantity of the top coal in the top coal caving mining process, the coal caving mode is related to the position of the top coal caving, the coal caving step pitch and the coal caving mode are different, the top coal caving speed and the effect are different, and the difference of the difficulty degree of maintaining the structural stability of the bracket-top coal-top plate is also determined. Meanwhile, a reasonable coal caving process is adopted, so that the roof pressure of a stope is controlled, and the fully mechanized caving mining recovery rate is improved.

By developing the key technical research on the caving coal mining of the soft and thick coal seam with the large dip angle, the caving performance of the top coal of the soft and thick coal seam is analyzed, a reasonable and feasible caving technology is adopted according to the occurrence condition of the coal seam, the caving technological parameters are optimized, and corresponding safety technical measures are formulated, so that the coal mining rate of the fully mechanized caving mining of the soft and thick coal seam with the large dip angle is improved, the dilution rate is reduced, and the important practical significance and the huge practical value are realized for ensuring the safe and efficient production of a mine.

Therefore, the invention provides a large-inclination fully mechanized caving mining coal caving method.

Disclosure of Invention

The invention aims to provide a large-dip-angle fully-mechanized caving mining caving method, which has important practical significance and great practical value for improving the coal recovery rate of the fully-mechanized caving mining of a soft and thick coal bed with a large dip angle, reducing the dilution rate and ensuring the safe and efficient production of a mine.

The invention is realized by the following technical scheme:

a large-inclination-angle fully-mechanized caving mining caving method comprises large-inclination-angle fully-mechanized caving mining top coal caving evaluation, a control method of large-inclination-angle working face fully-mechanized caving mining stability, determination of large-inclination-angle fully-mechanized caving mining reasonable caving step distance and determination of large-inclination-angle fully-mechanized caving mining reasonable caving mode:

the control method for the fully mechanized caving mining stability of the large-inclination-angle working face comprises the arrangement of the large-inclination-angle fully mechanized caving working face, a working face support stability control method, a working face coal wall stability control method and a fully mechanized caving mining safety prevention method, and specifically comprises the following steps:

the arrangement of the large-inclination-angle fully-mechanized caving face comprises the arrangement of face equipment and pseudo-inclined arrangement of the face; the arrangement of the working face equipment comprises that the lower end head is bent to a certain degree, the inclination angle is gradually decreased, the lower end head forms a stable support with a small inclination angle and even horizontally arranged, when the working face support is pushed, the lower end is firstly put and then put, and one support is leaned against the other support; the working face pseudo-oblique arrangement is a pseudo-oblique depression arrangement mode that the tail end of an air tunnel is ahead of the tail end of a machine tunnel along the advancing direction of the working face;

the working face support stability control method comprises the steps of support falling prevention, support skid prevention, conveyor skid prevention and support stability improvement;

the support prevents falling: adopt pseudo-oblique mode to arrange the working face when exploitation to reduce the working face inclination, the support need add anti-falling antiskid simultaneously, and specific control measure has:

(1) the support side guard plate is provided with a jack device and a side push spring, so that the support top beams are ensured to be tightly attached to each other, sufficient righting force is always provided, and the phenomenon of falling is prevented;

(2) a support adjusting jack is additionally arranged between top beams of adjacent supports, and when the supports topple, the supports can be adjusted by using the adjacent supports for supporting the top plate as fulcrums and adopting the jacks;

the support is anti-skid: the anti-skid of the support is that the anti-skid device is arranged at the front part or/and the rear part of the base, the anti-skid jack is arranged between two adjacent supports at the bridge crossing position at the front part, the anti-skid jack is mutually tensioned to prevent the supports from sliding downwards when the supports are moved, the first support at the row head at the rear part is mutually connected with the upper support through the connecting device of the jack and an anchor chain to draw and prevent the anti-skid, and the connecting position is that the base or the support with larger mining height is connected on a connecting; the rest supports are prevented from sliding downwards by adjusting the support of the base jack and the top shield beam side guard plate; when the support moves, the traction device is temporarily loosened, and is firstly tightened after being in place, and then the support is adjusted and then the column is lifted to support the top plate;

the conveyor is antiskid: an anti-skid jack is arranged between a bracket base and a conveyor, and can restrain the downward sliding of the conveyor when the conveyor is pushed, pulled and slid; for the front conveyor, when a hydraulic support is designed, the gap between the pushing device and the base is controlled, so that the pushing device can play a good guiding role, the downward sliding of the conveyor can be controlled when the conveyor is pushed to slide, and the downward sliding of the support can be controlled when the support is moved; for a rear conveyor of the top coal caving support, a bottom bracket is connected to the rear part of the support, and the rear conveyor is clamped on the bottom bracket to slide back and forth relative to the support so as to limit the left and right swinging;

when the inclination angle of the working surface is larger than 15 degrees, anti-skid measures need to be taken for the bracket, and the specific control measures comprise:

(1) the working face with the large inclination angle is arranged in a pseudo-depression inclined mode, and the inclination angle of the working face during mining is reduced;

(2) setting the pushing rod for whole-course guiding, controlling the gap between the pushing rod and the base within the range of 15-20 mm on one side, and keeping the gap between the pushing rod and the base unchanged when the pushing rod is at any position, thereby achieving the purpose of controlling the downward sliding of the conveyor;

(3) the conveyor is ensured not to slide downwards, the position of the conveyor is adjusted by controlling the pushing sequence of the conveyor, the head is pushed first, the conveyor can move upwards, and the tail is pushed first, so that the conveyor can slide downwards; an anti-skid jack is arranged between the adjacent support bases, and the position of the adjacent support is adjusted by taking the support with larger initial supporting force as a fulcrum; the device for preventing the conveyor from sliding downwards is arranged between the conveyor and the support, a group of devices can be erected at intervals of five, and when the conveyor is pushed, the conveyor can be pulled to move upwards by controlling the action of the anti-skidding jacks.

Moreover, the evaluation of the caving performance of the top coal in the large-dip-angle fully-mechanized caving mining comprises the steps of analyzing factors influencing the caving performance of the top coal, confirming evaluation functions of all factors influencing the caving performance of the top coal, and obtaining the category of the top coal caving performance of the evaluated coal seam block section by using a gray-fuzzy evaluation model;

and analyzing the factors influencing the caving property of the top coal and confirming the evaluation functions of the factors influencing the caving property of the top coal, wherein the factors comprise confirmation of the coal seam strength and the evaluation functions thereof, confirmation of the mining depth and the evaluation functions thereof, confirmation of the coal seam thickness and the evaluation functions thereof, confirmation of the coal seam inclination angle and the evaluation functions thereof, confirmation of evaluation values of the top and bottom conditions of the coal seam and the top and bottom conditions of the coal seam, and confirmation of the thickness and strength of the coal seam gangue and the evaluation functions thereof.

Moreover, the specific control measures for improving the stability of the bracket are as follows:

(1) selecting a bracket with the center distance of 1.75m or more, and widening the base under the condition of ensuring the space of the sliding jack after pulling;

(2) increase initial supporting power and working resistance, reduce bottom plate specific pressure: the initial supporting force of the bracket is increased, the working resistance is fully utilized during working, and the stability of the bracket can be improved; when the resistance of the bracket is increased, the bracket is required to be in good contact with the top bottom plate on the premise of not damaging the coal seam bottom plate; in addition, the specific pressure of the bottom plate is reduced by increasing the area of the base and adjusting the position of the action point of resultant force;

(3) controlling mining height, accelerating the advancing speed of a mining face: controlling the mining height, namely controlling the height of the support during mining; on the premise of not reducing the recovery rate of the working face, the mining height is controlled;

(4) the guide rail is arranged between the bases, can keep the distance between the supports and control the moving direction of the supports, has a similar anti-skid characteristic, is used for controlling the supports which move integrally, and plays the roles of guiding and skid resistance and adjusting the supports together with the adjusting jack arranged on the supports;

(5) installing a movable side guard plate: installing a top beam of a shield type bracket with a movable side guard plate and the movable side guard plate on a shield beam; when the inclination angle is larger than 15 degrees, the hydraulic thrust of the movable side guard plate needs to be increased, and a structure with movable two sides is adopted;

(6) the support is prevented from sliding downwards: adopting a pseudo-oblique working face arrangement;

(7) installing the anti-falling and anti-skidding jack, namely installing the anti-falling or anti-skidding jack on the hydraulic support and adjusting the jack among the supports; the movable side guard plates are all arranged on the shield support.

In addition, the stability control method of the coal wall of the working face has the following specific control measures:

(1) the initial supporting force and the working resistance are reasonably improved, and when the bracket is designed, a stand column with a larger cylinder diameter and a large-flow valve are selected;

(2) and (4) timely supporting under pressure, and immediately supporting top coal by moving the support under pressure when 1-2 supports of the lagging coal mining unit are delayed.

In addition, the fully mechanized caving mining safety precaution method has the following specific control measures:

(1) the safety prevention method of the stoping process comprises the following steps:

firstly, in the production process of a working face, the working face adopts a bidirectional coal cutting mode and an end or middle infinity type beveling feed mode;

adjusting the working surface to be pseudo-inclined (the inclination adjusting angle is 2-8 degrees), and ensuring that the front and back sliding and the transfer conveyor lap joint point meet the regulations of the cooperative industry;

thirdly, paving a double-layer diamond net in a top plate crushing and constructing area, laying a plate beam or a construction anchor cable mechanism top, fixing and forcibly jacking a leading anchor cable with the anchor cable length not less than 4.3m to jack the coal; preferably, the single anchor cable or the I-shaped steel anchor cable;

fourthly, in the normal production process of the working face, the coal discharging amount is controlled by a coal discharging worker, the door closing of the coal when the gangue is found is strictly executed in the coal discharging process, and the top plate is strictly forbidden to be emptied; the top plate is crushed, and the coal discharge amount is not carried out in the inclined area of the bracket, so that the bracket is prevented from being unstably inverted due to the fact that the upper part of the bracket is emptied;

(2) the anti-falling and anti-skid method of the bracket comprises the following steps:

firstly, the height of the coal mining machine is strictly controlled, the top bottom plate is ensured to be flat, the hydraulic support is tightly contacted with the top bottom plate, and the support is ensured to have enough initial supporting force to prevent the support from sliding downwards;

secondly, when the working face moves the support, the support must be moved under pressure, and when the support is moved, a side guard plate and a bottom lifting oil cylinder are used, so that the state of the support is adjusted in time, the support is ensured to be stable and reliable, and the initial supporting force of the front upright post is not lower than 24 MPa;

thirdly, when the support is pulled and moved, the support is wiped and moved under pressure, so that the support is pulled quickly with less descent, the empty roof time is reduced, and the roof is well controlled; after the support is moved, the support and the top plate are tightly contacted, the support is strictly prevented from inclining upwards and declining, and liquid is replenished for not less than 2 times per shift, so that the initial support force is ensured to meet the specified requirement;

reinforcing the management of the initial supporting force of the bracket, strictly controlling the stubble staggering of the adjacent brackets on the working surface, and strictly prohibiting the stubble staggering from exceeding 2/3 of the width of the top beam side guard plate of the bracket;

fifthly, when the support is pulled, the lower support moves forwards as a guide rail, when the distance between the supports exceeds the specification, the distance between the bases is firstly adjusted, then the inclination is adjusted, and the support is pulled after the adjustment, so that the middle part of the support is prevented from falling down; when the frame is adjusted, two persons can respectively operate two adjacent frames, one person is responsible for pulling the frame, and the other person operates the side guard plate of the lower bracket; when two persons operate, other persons withdraw out of the front and rear three brackets;

the transition support prevents backward slipping: the lower end of the working surface adopts a ZFT25000/23/45 type end bracket, and the 1# and 2# end brackets are provided with anti-falling oil cylinders, so that the stability of the end head bracket can be ensured; the top beam of the working face machine head transition support (the head frame) abuts against the top beam of the end support, the transition support can be effectively controlled to prevent falling, and when the transition support is pulled, the side protective plate of the end support is taken as a guide rail to move forwards, so that the support adjusting effect is achieved; when the support is unstable, the side guard, the support adjusting jack and the single column of the support are used for leaning against the support in time;

the first support of row is prevented slipping backwards: the lower row head support group consists of 5 frames, and top beams of the lower three frames and bases of the upper three frames are tensioned by a jack and a circular chain to prevent falling; the front sections of the lower three bases are mutually pulled by two jacks with cross connectors and are used for picking frames; the lower three frames are also provided with an anti-skid device consisting of a jack and a round-link chain; fourthly, five frames are used when the inclination angle of the working surface is more than 45 degrees or the top plate at the lower end of the working surface is crushed in a large area, so that the lower three frames are pulled; in the rack moving process, a hydraulic control one-way valve in an oil path of the jack is closed, and a medium-flow safety valve overflows to ensure that the lower rack does not topple; the upper row head support group consists of three supports, and because of being limited by the transmission device of the conveyor, the bases of the three supports lag behind the normal supports by one step pitch of moving the supports, and the top beams, the pushing rods and the side guard plates of the three supports are correspondingly lengthened; in order to ensure the normal support of the top plate, an auxiliary jack and an adjusting jack for adjusting the position of the lower end of the auxiliary jack are added below the lengthened top beam; the upper row head bracket only comprises an anti-falling device without an adjusting bracket and an anti-sliding device; when the rack is moved from bottom to top, 1 rack is moved first, and then the bracket below the rack is moved;

the middle support is prevented from slipping backwards: when the distance between the supports exceeds a set distance, the distance between the bases is adjusted by the base leaning frame oil cylinder, then the inclination is adjusted by the support side protecting plate leaning frame, the supports are kept stable, the forward leaning and backward leaning are avoided, and the middle part leaning frame caused by the downward leaning of the supports is prevented; when the support is seriously inclined, the support is ensured to be straight and stable by utilizing the side protection of the support and the timely adjustment of the single hydraulic prop;

(3) the stand is inverted and bitten by adopting a single column adjusting method:

firstly, when the rack is processed, the 5 racks above the processed rack are lifted tightly to ensure that the initial supporting force reaches the standard; lowering the processed support by 200mm, leaning against the support by using 2 single columns, propping a column head of a first single column on a top beam of the support, propping a column root on a lower adjacent support base, propping a column head of a second single column on a tail beam of the support, propping the column root on a lower rear chute seat, carrying out remote liquid injection operation to level the support base, then tightly lifting the support, and adjusting the support from top to bottom one by one during support adjustment;

secondly, after the single column is erected, the support is pulled and moved, and in the process of pulling the support, the support is also pulled and moved in a matching manner with the side guard plate; meanwhile, the single column is remotely supplied with liquid, the top beam is leveled, the bottom lifting oil cylinder and the side guard plate of the support are utilized to lift the base on one side of the inverted frame, a plate beam, a road beam and the like are padded below the base, and finally the support is lifted tightly, and the support is required to be adjusted from top to bottom one by one when adjusted;

thirdly, in order to prevent the support from continuing to have the tendency of falling after being pulled, a single column prop support is adopted, and the support position is the same as that of the leaning frame;

fourthly, when the unit cuts coal, a method of machine chasing and frame pulling or frame moving under pressure is adopted; when the working surface slice has large side depth, the coal is cut after the frame is pulled in advance;

when the machine set reaches the support reversing area, after the machine set cuts a coal, the machine set is retreated by more than 10m, all running equipment on the working face is locked, and the support leaning operation is carried out, wherein the support leaning process is the same as the above;

(4) the coal mining machine and cable antiskid method comprises the following steps:

firstly, the coal mining machine is provided with a frequency converter and a hydraulic brake, when the coal mining machine cuts coal downwards, under the condition that the gliding force of the coal mining machine is greater than the resistance force borne by the coal mining machine, the power voltage and the frequency of a traction motor are changed through the frequency converter to realize the speed regulation of the traction motor, and the descending speed of the coal mining machine is effectively controlled; when the coal mining machine stops, the hydraulic brake acts to prevent the unit from sliding downwards;

secondly, the coal mining machine cable is antiskid: the anti-skid device is arranged on the tail cable supporting groove, the cable supporting is slowly lowered by operating a handle of the anti-skid device in the coal cutting process to prevent the cable supporting from slipping down, when the coal cutting is stopped, a brake handle of the anti-skid device is firmly fixed with the cable supporting frame by using a double-strand 8# iron wire, and an operator of the cable supporting anti-skid device sends a special person for operation;

thirdly, the power cable of the working surface is antiskid: all the other cables except the coal mining machine cable on the working surface are arranged in a forward sliding cable trough, and in order to prevent the cables from sliding downwards, hoisting belts are used for binding the cables and fixing the cables with the sliding trough every 10 m;

(5) antiskid method for scraper conveyor

Firstly, arranging anti-skid jacks, arranging one anti-skid jack every 10-15 frames on a working face, connecting one end of each anti-skid jack with a middle groove of a scraper conveyor, connecting the other end of each anti-skid jack with a hydraulic support base, and tensioning the anti-skid jacks when the scraper conveyor is pushed;

secondly, the rear scraper conveyor is in flexible connection with a circular chain, when coal is discharged due to the fact that equipment slips downwards, the support slips downwards by adjusting the length of the chain ring, the slip moving sequence from bottom to top must be strictly executed in the stoping process, and when coal is discharged due to the fact that the conveyor slips downwards seriously, the coal can be processed in a chute shrinkage mode.

And the method is used for underground mining coal mine with the average inclination angle of the coal seam of 20-30 degrees.

And the reasonable coal caving step pitch of the large-dip-angle fully mechanized caving mining is determined as follows: adopting a coal caving mode of one coal caving step (coal caving step pitch is 0.8 m).

And the reasonable coal caving mode of the large-dip-angle fully mechanized caving mining is determined as follows: coal is sequentially discharged in a single wheel mode from top to bottom.

The invention has the positive effects that:

1. the method adopts a reasonable and feasible coal caving technology according to the occurrence condition of the coal bed, optimizes the coal caving technological parameters, and formulates corresponding safety technical measures, thereby having important practical significance and great practical value for improving the coal recovery rate of fully mechanized caving mining of the soft and thick coal bed with large inclination angle, reducing the dilution rate and ensuring safe and efficient production of the mine.

2. The invention provides a control method for guaranteeing the fully mechanized caving mining stability of a large-inclination working face in detail in a large-inclination fully mechanized caving mining caving method for the first time, and the control method is in a leading position in the industry; the invention has reasonable design, simple technology and convenient construction, and the adopted stability control method of the coal wall of the working face and the fully mechanized caving mining safety precaution method can improve the stability of the coal wall of the working face, effectively ensure the safety problem of workers in the coal seam mining process, reduce the occurrence probability of safety accidents and realize safe and efficient production of the working face.

3. The invention effectively solves the problems that the coal is discharged from the lower support and the upper part is 5-8 in the coal discharging process of the area with a large inclination angle^#The coal on the top of the frame is empty, so that serious potential safety hazards exist, the phenomenon of the coal on the top of the upper frame is controlled by adopting a small amount of coal discharge of the lower frame, the technical problem of serious waste of coal resources is caused, and the safety problem of operators is fully guaranteed; since the technology of the invention is adopted in the colossal tower mine, the production safety accidents are reduced by 80 percent.

4. The invention improves the stability and safety of the working surface on the whole for the arrangement of the working surface with large inclination angle, simplifies the lap joint matching of the conveyor and the loader, and is convenient for production and management.

5. The pseudo-dip arrangement of the invention leads the tail end of the air tunnel to the tail end of the machine tunnel along the advancing direction of the working face, and the arrangement mode has the outstanding advantages of effectively inhibiting the coal wall caving of the working face with large dip angle; the coal cut by the coal cutter moves towards the coal wall side, so that the coal flying threat to miners during pedestrian path operation is eliminated; the stability of the coal wall of the pseudo-pitching inclined working face is optimal.

Drawings

FIG. 1 is a work surface equipment layout;

FIG. 2 is another work surface equipment layout;

FIG. 3 is a diagram of a coal wall unit space stress model and a unit body stress analysis;

FIG. 4 is a force analysis diagram of the bracket during operation;

FIG. 5 is a top beam fall prevention plan view;

FIG. 6 is a design view of anti-slip between brackets;

FIG. 7 is a design view of the skid resistance between the conveyor and the support;

FIG. 8 is a diagram of a once-cut top coal migration feature;

FIG. 9 is a two-blade one-top coal migration feature;

FIG. 10 is a simulation of a single round of sequential coal discharge;

FIG. 11 is a simulation of a single round of alternate coal caving;

FIG. 12 is a simulation of a multi-round sequential coal discharge.

Description of the drawings: in FIG. 3, α -coal seam inclination; p_c-pressure of the roof and overlying coal rock mass on the unit cell; g₀-the weight of the coal wall unit cell; g₁-the gravity of the adjacent unit cell; n is a radical of_d-the holding force of the bottom plate or bottom adjacent block to the unit body; f. of_r-friction of the top plate or top unit body against the body unit body; f. of_d-friction of the bottom plate or bottom unit body against the body unit body; c_ω-the sum of 4 structural surface adhesion forces; f_c-lateral forces of adjacent elementary blocks on the block in the true inclination direction; in fig. 4, (a) -normal working stent force diagram; (b) -an lodging limit balance diagram; g-support dead weight, N1-initial supporting force, N2-bottom plate counter force, N-top plate pressure resultant force, F1 and F2 are respectively expressed as extrusion force between upper and lower adjacent supports.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings. The detailed description of the invention can be carried out using methods known in the art.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

A large-inclination-angle fully-mechanized caving mining caving method comprises large-inclination-angle fully-mechanized caving mining top coal caving evaluation, a control method of large-inclination-angle working face fully-mechanized caving mining stability, determination of large-inclination-angle fully-mechanized caving mining reasonable caving step distance and determination of large-inclination-angle fully-mechanized caving mining reasonable caving mode, and is characterized in that:

the arrangement form of the large-dip-angle working face equipment directly influences the anti-falling and anti-skidding effect, alpha in figures 1 and 2 represents the dip angle of the coal bed, as shown in figure 1, when the large-dip-angle thick coal bed is arranged on the working face equipment, a certain bending is formed towards the downward end, the dip angle is gradually decreased, the stability of the lower end head support is increased, the arrangement has the advantages that a stable support with a small dip angle or even horizontally arranged is formed at the lower end head, the working face support is pushed to move downwards and upwards, one support is close to the other support, the arrangement mode of preventing falling and gliding is convenient to produce and manage, and the large-dip-angle and thick coal bed working face equipment is suitable for large-dip angles and.

The working face with small coal seam thickness or relatively small inclination angle usually adopts the arrangement mode shown in figure 2, the mode is close to horizontal arrangement, but the working face does not have stable support of a horizontal end, production management is inconvenient, certain potential safety hazards also exist, and the difficulty of the arrangement mode is to solve the problem that the lower row head support slides down, especially the first 1 st row head support. For the arrangement of the working surface with the large inclination angle, the arrangement mode shown in figure 1 of the invention is adopted, so that the stability and the safety of the working surface equipment are integrally improved, the overlapping fit of a conveyor and a loader is simplified, and the production and the management are convenient. The invention also uses the arrangement mode in the fully mechanized caving mining of the working face with large inclination angle for the first time, and obtains good production effect.

According to the deformation process and characteristics of the coal body in front of the coal wall, the coal body can be divided into a fracture (fragment) area, a plastic area and an elastic area along the trend.

Considering that the coal wall of the working face with a large inclination angle is in a broken (crushed) state and the stress state of the coal wall is changed after the working face is inclined, as shown in fig. 3, 3 simplified models of coal wall unit space stress are established. The plane of bcef is the coal wall, and it is assumed that 4 planes except bcef in the pentahedron abcdef represent fracture surfaces generated after the crack is penetrated and expanded under load, and are also sliding surfaces of the coal wall units separated from the coal wall matrix.

The stress analysis of the coal wall of the working surface under the 3 arrangement modes is as follows.

The coal wall unit body of the pseudo-dip inclined working surface is in a mechanical equilibrium state along the coal bed inclination direction and the normal direction:

tendency: f_c+C_ω+f_d-f_r-G₀·sinα＝0 (1)

Normal direction: p is a radical of_c+G₀·cosα-N_d＝0 (2)

The coal wall unit body of the true inclined working face is in a mechanical equilibrium state along the inclined direction and the normal direction of the coal bed:

tendency: f_c+C_ω+f_d-f_r-(G₀+G₁)sinα＝0 (3)

Normal direction: p is a radical of_c+G₀·cosα-N_d＝0 (4)

The pseudo-elevation working face coal wall unit body is in a mechanical equilibrium state along the coal bed inclination direction and the normal limit:

tendency: c_ω+f_d-f_r-(G₀+G₁)sinα＝0 (5)

Normal direction: p is a radical of_c+G₀·cosα-N_d＝0 (6)

The instability condition of the coal wall unit body along the coal bed inclination direction is as follows:

as can be seen from the formula (7), compared with a pseudo-pitching-inclined working face, the coal wall of the pseudo-pitching-inclined working face is easier to achieve the instability condition, and the true pitching-inclined working face is inferior. Therefore, the stability of the coal wall of the pseudo-depression inclined working face is optimal in the 3 arrangement modes.

The inclined direction of the working face is opposite to that of the pseudo-inclined-downward arrangement, namely the tail end of the air tunnel is ahead of the tail end of the machine tunnel along the advancing direction of the working face. Compared with a pseudo inclined working surface, the method has the outstanding advantage that the coal wall caving of the working surface with a large inclination angle can be effectively inhibited. And the coal cut by the coal cutter moves towards the coal wall side, so that the coal flying threat to miners during the pedestrian path operation is eliminated.

Stability analysis of the large tilt angle stent:

when the hydraulic support works normally in a large-inclination working surface, the self weight G and the initial supporting force N of the support₁Counter-force N of the bottom plate₂Resultant force N of top plate pressure and extrusion force F between upper and lower adjacent frames₁And F₂The combined action of the two parts is in a balanced state, as shown in fig. 4, if the above balanced state of the bracket is broken, the resultant force action point of the bracket is deviated from the base, and the bracket is unstable. At the moment of instability and overturning of the support, the counter force N of the bottom plate₂Acting at O.

According to the moment limit equilibrium conditions available (see fig. 4 (b)):

b is the horizontal distance (self-stabilizing arm) between the self-weight action direction of the bracket and the lower edge of the bracket base, and is mm;

h-height of the bracket, mm;

b-width of the bracket base, mm;

H_gheight of center of gravity, mm.

As can be seen from formula (9), b and H_gInversely proportional, B is proportional to B, and B is inversely proportional to α. I.e. the lower the centre of gravity of the bracket, the wider the base, and the stronger the bracket's ability to adapt to inclination and pressure.

As can be seen from fig. 10, the self-stability arm b of the bracket becomes larger as the width of the bracket base increases and becomes smaller as the height of the center of gravity of the bracket increases, i.e., the wider the bracket base, the lower the center of gravity and the lower the support height, the larger the self-stability moment of the bracket, and the stronger the anti-toppling capability of the bracket. In the stress analysis, the external load acting force from the slipping top coal and gangue on the tail beam of the bracket is ignored. If the horizontal resultant force of the external load is larger than the friction force of the bracket during normal work, the stress of the bracket in the horizontal direction is unbalanced, and the bracket can be unstable and even topple over. For a working face with an average inclination angle of a mine coal seam of 20-30 degrees, the falling gangue in a goaf can move to the lower section of the working face along a bottom plate under the action of gravity, so that the goaf at the lower part of the working face is densely filled, the gangue in the goaf at the upper part is insufficiently filled, the risk and complexity of toppling over of a hydraulic support at the upper part of the working face are increased, and therefore the stability of the support of the working face must be controlled by taking measures.

(2) a support adjusting jack is additionally arranged between top beams of adjacent supports, when the supports topple, the adjacent supports for supporting the top plate can be used as fulcrums, and as shown in fig. 5, the positions of the supports are adjusted by the jack;

the support is anti-skid: as shown in fig. 6, the support skid resistance is that skid-proof devices are arranged at the front part or/and the rear part of the base, skid-proof jacks are arranged between two adjacent frames at the gap bridge at the front part, the two frames are mutually tensioned to prevent the frames from sliding downwards when moving the frames, the 1 st frame at the row head at the rear part is mutually connected with the upper support by using a connecting device of the jacks and anchor chains to draw and resist skid, and the connecting position is that the base or the support with larger mining height is connected on a connecting rod; the rest supports are prevented from sliding downwards by adjusting the support of the base jack and the top shield beam side guard plate; when the support moves, the traction device is temporarily loosened, and is firstly tightened after being in place, and then the support is adjusted and then the column is lifted to support the top plate;

(3) the conveyor is ensured not to slide downwards, the position of the conveyor is adjusted by controlling the pushing sequence of the conveyor, the head is pushed first, the conveyor can move upwards, and the tail is pushed first, so that the conveyor can slide downwards; as shown in fig. 7, an anti-skid jack is arranged between the adjacent bracket bases, and the position of the adjacent bracket is adjusted by taking the bracket with larger initial supporting force as a fulcrum; the device for preventing the conveyor from sliding downwards is arranged between the conveyor and the support, a group of devices can be erected at intervals of five, and when the conveyor is pushed, the conveyor can be pulled to move upwards by controlling the action of the anti-skidding jacks.

Preferably, the evaluation of the caving performance of the top coal in the large-dip-angle fully-mechanized caving mining comprises analyzing factors influencing the caving performance of the top coal, confirming evaluation functions of the factors influencing the caving performance of the top coal, and obtaining the category of the top coal caving performance of the evaluated coal seam block section by using a gray-fuzzy evaluation model;

and analyzing the factors influencing the caving property of the top coal and confirming the evaluation functions of the factors influencing the caving property of the top coal, wherein the factors comprise confirmation of the coal seam strength and the evaluation functions thereof, confirmation of the mining depth and the evaluation functions thereof, confirmation of the coal seam thickness and the evaluation functions thereof, confirmation of the coal seam inclination angle and the evaluation functions thereof, confirmation of evaluation values of the top and bottom conditions of the coal seam and the top and bottom conditions of the coal seam, and confirmation of the thickness and strength of the coal seam gangue and the evaluation functions thereof. The evaluation of the top coal caving performance is specifically explained by taking a colossal colonnan coal mine of the Huzhou coal and electricity group as a background, and other coal mines with the same or similar conditions can be used as references:

firstly, factors influencing the caving property of the top coal and evaluation functions thereof comprise:

(1) and (4) the strength of the coal bed. The strength of the coal bed is controlled by the hardness of the coal bed and the development degree of the joint cracks, and the combined action of the hardness of the coal bed and the joint cracks influences the dischargeability of the top coal, the hardness of the coal bed has an important influence on the dischargeability of the top coal, and the top coal can be automatically crushed by utilizing the action of mine pressure under the condition that the hardness coefficient f of the coal is less than or equal to 2; for coal seams with f being more than 2 and less than or equal to 3, auxiliary measures such as drilling and blasting, coal seam water injection and the like are required; when the coal is caving in a gently inclined coal bed, if the hardness of the coal is small, namely f is less than 0.6-0.8, the coal wall is easy to slice, and due to the influence of the supporting pressure of the coal wall, the roof falls forward, which brings great difficulty to the management of the roof of a working face. In general, in a gently inclined coal seam, when f is 0.8 to 2.0, the effect of caving is good. However, in a steep coal seam, the soft coal is beneficial, and when f is 0.3-1.0, the top coal caving effect is good. Generally, the coal seam contains bedding, joints and cracks in different degrees, and the weak surfaces and the structural surfaces weaken the integrity of the coal seam to a great extent and reduce the strength of the coal seam, so that the method is favorable for caving the coal. The seam joints and cracks develop, and the top coal caving effect is good; if the seam joints do not develop, the top coal is not easy to fall. The evaluation function of the coal bed hardness is as follows:

in the formula, p₁₁Is the hardness coefficient of coal.

The development degree of the coal seam joint crack belongs to qualitative factors, and is evaluated in a classification mode, and classification and evaluation values are shown in table 1.

(2) And (4) mining depth. The practice of roadway top coal caving mining discovers that a coal caving roadway has large deformation before coal caving starts on a working face with large mining depth, and sometimes the top plate of the coal caving roadway sinks to more than 300mm, which indicates that top coal has been deformed under the action of mine pressure; and on the working face with smaller mining depth, after the coal discharge roadway is tunneled for several months, the support is still unstressed, which shows that the influence of the mine pressure on the top coal is not great. The evaluation function for the mining depth is:

in the formula, p₂Is the face depth, m.

(3) The thickness of the coal seam. The top coal caving of the steeply inclined coal seam roadway is different from the horizontal sectional top coal caving. For the latter, the larger the coal seam thickness, the better the caving effect. However, in the former case, the thickness of the coal seam is required to be appropriate. If the thickness is too small, the direct roof can be broken in advance and discharged together with the top coal, so that not only the coal quality is influenced, but also the top coal is lost in a large amount; the thickness is too large, the top coal close to the bottom plate is difficult to be loosened fully, and the top coal is difficult to be released, so the recovery rate of the top coal is influenced. Practice shows that the thickness of the coal seam suitable for roadway top coal caving mining is 2-10 m, and when the thickness of the coal seam is 4-6 m, the technical and economic effects are the best. The evaluation function of the coal seam thickness is as follows:

in the formula, p₃Is the coal seam thickness, m.

(4) And (4) coal seam inclination angle. The coal seam inclination angle has important influence on the roadway caving coal mining. When the inclination angle is larger, the gravity of the coal body is easily larger than the resultant force of other forces to cause the coal body to collapse, which is beneficial to the discharge of the coal body. But the larger the coal seam inclination angle is, the lower the pressure of the top plate on the coal seam is. When the inclination angle is 90 degrees, the force acting in the vertical direction only has the gravity of the broken coal gangue in the goaf above the top coal, and the coal bed is not easy to collapse. Practice shows that the inclination angle of the coal seam suitable for roadway top coal caving mining is 40-90 degrees, and the effect is best when the inclination angle is 65-75 degrees. The evaluation function of the coal seam dip angle is as follows:

in the formula, p₄Is the coal seam dip angle, (°).

(5) The top and bottom conditions of the coal seam. The influences of the conditions of the top and the bottom of the coal seam on the caving coal mining top coal caving performance of the roadway are mainly the stability of the immediate roof and the stability of the bottom plate. The direct roof crushing influences the recovery of the top coal and increases the gangue content; the direct roof is stable, the suspension area is large, and the placeability of the top coal is good. The influence of the stability of the floor of the steeply inclined coal seam on the mining of the roadway caving coal is mainly reflected in that when the floor is unstable, the difficulty of coal caving is increased and the coal quality is reduced due to the slippage of the floor. The classification and evaluation values of the top and bottom conditions of the coal seam are shown in table 1.

(6) And (5) coal seam gangue inclusion. The top coal caving production practice shows that the gangue below 0.3m mostly falls in a sheet shape and a plate shape, and the caving and the discharging of the top coal are not greatly influenced. However, if the thickness of the gangue is more than 0.4m, the gangue is likely to block the coal discharge port because of the large lump even if the gangue can be blown up. Meanwhile, the thick layer of gangue inclusion can greatly increase the gangue content of the coal discharge. The gangue in the coal seam is like a connecting tie bar in a plate structure, and plays a role in reinforcing the strength of the coal body, so that the fracturing and the displacement of the top coal are difficult. This effect is particularly pronounced when the strength of the gangue is greater. Therefore, the thickness and the strength of the gangue have influence on the dischargeability of the top coal, and the evaluation functions are respectively as follows:

in the formula, p₆₁The ratio of the total thickness of the gangue to the thickness of the coal bed is shown; p is a radical of₆₂The compression strength of the gangue is MPa.

Other mining conditions: the geological condition of the gas. The phenomenon of spalling in the coal seam after the high-gas coal seam is exposed is proved by experiments and is also detected by field industrial tests, and the high gas content of the coal seam is favorable for crushing top coal; hydrogeological conditions. The strength of the coal bed is greatly influenced by the water content, the more the water content is, the lower the strength of the coal bed is, the more easily the coal body is broken, and the better the placeability is; and thirdly, the coal bed is dangerous to fire naturally. Compared with the slowly inclined fully mechanized top coal caving, the top coal caving of the steeply inclined coal seam roadway has the advantages that the possibility of natural ignition of the coal seam is relatively low due to the short mining time of the working face. However, the goaf still has the danger of spontaneous ignition due to the remaining coal which is not discharged completely. The classification and evaluation values of other mining conditions are shown in table 1.

TABLE 1 Classification of qualitative factors and evaluation values

Categories	1	2	3	4
					Degree of development of joint crack of coal seam	Development of	Moderate development	Does not develop	Is not developed very much
Coal seam roof (floor) stability	Stabilization	Moderate stability	Instability of the film	Is very unstable
					Geological conditions of gas	High gas	Low gas	Gas gushes out	Coal and gas outburst
Hydrogeological conditions	Moisture content	Moderate moisture	Non-moist	Drying
					Danger of spontaneous ignition of coal seam	Non-self-ignition	Difficult to self-ignite	Easy to self-ignite	Easily self-ignited
Evaluation value	5.0	3.5	2.0	0.5

Secondly, establishing a gray-fuzzy evaluation model:

the grey-fuzzy evaluation model is established, namely the grey statistical method and the fuzzy mathematical theory in the grey decision-making method are applied to establish the caving evaluation model of the top coal of the steeply inclined coal seam.

Let V be { V ═ V₁,V₂,V₃,V₄,V₅Good, generally, poor, bad are evaluation grays, corresponding to V₁～V₅With a corresponding standard function, i.e. f_k(k is 1,2, …,5) is an evaluation value μ (p)_i) (or μ (p)_ij) Value belonging to the kth category of evaluations. With f_k(r_i) An evaluation value mu (p) representing a coal seam block to be evaluated_i) (or μ (p)_ij) The value obtained by the k standard function of the evaluation gray class, the coal seam block belongs to the gray statistic of the k evaluation classWherein, a_iThe weight value of the index is determined comprehensively by experts and engineering technicians with abundant field experience by adopting an analytic hierarchy process; m is the index number. Coal seam block gray statistics

Number of grey scales b of coal seam block section belonging to k-th evaluation_k＝C_kand/C. Therefore, the coal seam block to be evaluated belongs to the evaluation ash class V₁～V₅Weight vector B of₀＝(b₁,b₂,b₃,b₄,b₅)。

The model can be used for multi-factor evaluation of a single layer. Because the factors for evaluating the caving coal caving ability comprise two levels, multi-level fuzzy evaluation is required to be carried out, and the steps are as follows: the gray evaluation model can obtain the evaluation result B of the level 1_i1＝(b_i1,b_i2,b_i3,b_i4,b_i5) (i ═ 1,2, ^, 7); evaluation value B of level 2 ═ AB₁＝(b₁,b₂,b₃,b₄,b₅) Wherein, A is a weight vector of the evaluation index; b is₁Is composed of B_i1A matrix of components. Let b^*＝b_j＝max{b₁,b₂,b₃,b₄,b₅And f, the top coal openness of the evaluated coal seam block belongs to the jth category.

The model is applied to calculate the top coal caving property of the steeply inclined coal seam mined by roadway top coal caving, and the calculation result is compared with the corresponding coal caving effect, so that the following conclusion can be obtained: the top coal of class I (good placeability) can be smoothly released without taking measures; the top coal of II type (with better placeability) generally needs to adopt measures such as loosening blasting and the like to be also released; the III (general dischargeability) top coal can be discharged by adopting measures such as coal seam water injection, vibration gun discharge and the like; the IV-type (poor placeability) and V-type (poor placeability) top coals are difficult to be released, and the roadway top coal caving mining is not suitable.

According to the physical and mechanical test result of the coal rock and the actual situation on site, the caving performance of the top coal on the 9-301 working face is calculated and analyzed as follows:

(1) coal seam strength (P)₁): the hardness p11 of the 9# coal seam is 1.16, and the mu (p11) is 4.68 according to calculation.

(2) And (3) mining depth: the average mining depth p2 of the working face of 9-301 is 460m, and mu (p2) is 4.5 according to calculation.

(3) The coal seam thickness, 9-301 working face coal seam average coal thickness p3 is 11.8m, and according to calculation, mu (p3) is 0.

(4) The dip angle of the coal seam is taken as the average dip angle p of the 9# coal seam₄20 °, μ (p4) ═ 0 by calculation.

(5) Coal seam roof and floor conditions (P5): medium development, medium stability, low gas, medium humidity, easy spontaneous combustion, evaluation value: μ (P5) ═ 3.5;

(6) coal seam gangue inclusion: taking the thickness of the sandwiched gangue as 0.24m, and obtaining p according to calculation₆₁＝0.24/11.8＝0.02，μ(p₆₁)＝4.6，μ(p₆₂)＝5；

μ (p11) values evaluated in the first category: f1(r11) is 0.936, second class: f2(r11) is 0.88, third: f3(r11) is 0.43, fourth: f4(r11) is 0, fifth: f5(r11) is 0;

μ (p2) values evaluated in the first category: f1(r2) is 0.9, second class: f2(r2) 0.875, third: f3(r2) is 0.47, fourth: f4(r2) is 0, fifth: f5(r2) is 0;

μ (p3) values evaluated in the first category: f1(r3) is 0, second class: f2(r3) is 0, third: f3(r3) is 0, fourth: f4(r3) is 0, fifth: f5(r3) is 0;

μ (p4) values evaluated in the first category: f1(r4) is 0, second class: f2(r4) is 0, third: f3(r4) is 0, fourth: f4(r4) is 0, fifth: f5(r4) is 0;

μ (p5) values evaluated in the first category: f1(r5) is 0.7, second class: f2(r5) 0.875, third: f3(r5) is 0.87, fourth: f4(r5) is 0.25, fifth: f5(r5) is 0;

μ (p61) values evaluated in the first category: f1(r61) is 0.92, second: f2(r61) is 0.8, third: f3(r61) is 0.41, fourth: f4(r61) is 0, fifth: f5(r61) is 0;

μ (p62) values evaluated in the first category: f1(r62) is 1, second type: f2(r62) is 0.75, third: f3(r62) is 0.5, fourth: f4(r62) is 0, fifth: f5(r62) is 0;

the grey statistics of coal seam block sections belonging to the k-th evaluation are as follows:

(a_itaking 1 out of the table, and then carrying out the following steps of,

calculating to obtain C₁＝4.456，C₂＝4.18，C₃＝2.68，C₄＝0.25，C₅＝0

Coal seam block gray statistics

Number of grey scales b of coal seam block section belonging to k-th evaluation_k＝C_k/C.

b₁＝0.385 b₂＝0.361 b₃＝0.232 b₄＝0.02 b₅＝0

Therefore, the first and second electrodes are formed on the substrate,

b_j＝max{b₁,b₂,b₃,b₄}＝b₁

therefore, the top coal placeability of the coal seam block section belongs to the type I, and the placeability is good.

Preferably, the method for improving the stability of the stent comprises the following specific control measures:

Preferably, the method for controlling the stability of the coal wall of the working face comprises the following specific control measures:

Preferably, the fully mechanized caving mining safety precaution method specifically comprises the following control measures:

(5) antiskid method for scraper conveyor

Preferably, the method is used for underground mining coal mining with the average inclination angle of the coal seam of 20-30 degrees.

Preferably, the reasonable coal caving step pitch of the large-dip-angle fully mechanized caving mining is determined as follows: adopting a coal caving mode of one coal caving step (coal caving step pitch is 0.8 m).

The coal caving step distance is the distance pushed by the working face between two coal caving steps, and the reasonable coal caving step distance is crucial to improving the mining rate and maintaining the stability of the top plate of the stope. Considering the coal caving process mode commonly used in the current field, two process modes are analyzed; once cutting (coal discharging step distance is 0.8m) and once cutting (coal discharging step distance is 1.6 m).

Two kinds of numerical simulation analysis of the coal caving step distance, as shown in fig. 8 and 9, can analyze the influence of the coal caving step distance on the stability control of the roof (coal) on the premise of ensuring the recovery rate. If the coal caving step is too large and is obviously larger than the minor axis of the coal caving ellipsoid, the gangue above the bracket reaches the coal caving port before the top coal in the step range, and the coal loss of a ridge is formed in the direction of the goaf. The larger the coal discharge step, the more the "ridge" coal is damaged. The stress condition of a top plate above the support is changed due to the support effect of the 'back' coal damage, and the crushing of the top plate is non-uniform, so that the stress effect difference of the back parts of top beams and tail beams of different supports is large, the stability of the support is not facilitated, and the overall support effect of the support is influenced. Meanwhile, the coal discharging step is too large, the impact of a large number of broken top plates and coal bodies above the support on the support is increased, and the stability of the support is also influenced. If the coal caving step is too small and obviously smaller than the minor axis of the coal caving ellipsoid, the gangue in the goaf can reach the coal caving port before the top coal, so that the gangue is discharged and the coal is reserved, and the control of the support on the top plate is also not facilitated. According to the simulation, the coal caving mode of one coal caving (the coal caving step distance is 0.8m) is more reasonable than the other mode, and the top and the side waste rocks of the goaf can reach the coal caving port simultaneously, so that the control of the top plate by the support is facilitated.

Preferably, the reasonable coal caving mode of the large-inclination fully mechanized caving mining is determined as follows: coal is sequentially discharged in a single wheel mode from top to bottom.

The coal caving mode is a general term of a combined coal caving method comprising the coal caving sequence, the coal caving times and the coal caving quantity of each coal caving opening, the number of the coal caving openings which are simultaneously opened along the working face and the like. The coal caving mode not only can influence the extraction rate, the gangue content and the coal caving speed of the top coal, but also can have great influence on a stope roof system. Two coal caving modes of the fully mechanized caving face of the soft thick coal seam with large inclination angle are provided, as shown in fig. 10-12, the coal caving modes are respectively the top coal moving particle flow conditions of single-wheel sequential coal caving, single-wheel interval coal caving and multi-wheel sequential coal caving.

The model is established under the condition of 3.2m mining height by taking the 9-301 working face of the C.Huzhou coal and electricity group colonnan coal mine, and taking a 35-degree large-inclination coal seam as an example. The model adopts 4 continuous groups of supports as one group, two groups of support models are set, the simulation is respectively carried out according to the following three schemes, and the coal caving effects of different coal caving modes are analyzed and compared:

(1) coal release at intervals in a single round: firstly, opening coal discharging ports on No. 1, No. 3 and other single supports, closing the coal discharging ports when gangue is found at the coal discharging ports, and at the moment, leaving a certain ridge coal at the coal discharging ports. And (5) lagging a certain distance to perform coal discharge of the double-size bracket, and discharging the remained ridge coal.

(2) Single-round sequential coal caving: and (4) sequentially discharging coal according to No. 1 and No. 2 coal discharge ports, and closing the coal discharge ports after the gangue is seen.

(3) Coal caving in sequence in multiple rounds: and (4) discharging coal according to the sequence of discharging the No. 1 and the No. 2 supports together, and closing a coal discharging opening after the gangue is seen.

Under the conditions of coal cutting of 3.2m and coal caving of 8.6m, numerical simulation is carried out on a 9-301 working face coal caving mode, and the recovery rate of multi-round sequential coal caving is 85.7 percent at most, 3 percent higher than 82.7 percent of single-round alternate coal caving and 2.6 percent higher than 83.1 percent of single-round sequential coal caving. The top coal caving rate of the single round of alternate caving is the lowest, the top coal caving rate of the single round of sequential caving is higher than that of the single round of alternate caving, and the top coal caving rate of the multi-round of sequential caving is the highest. As shown in fig. 12, although the top coal caving rate is high in the multi-round sequential coal caving mode, the top coal caving starts simultaneously due to the fact that a plurality of supports start to perform coal caving once, the top plate is obviously influenced due to the dual functions of gravity and the top coal caving from top to bottom, and therefore the top plate of the stope starts to sink towards the coal caving space, the control difficulty of the top plate of the stope is high, and operators on dangerous working faces are caused. Although the single-wheel interval coal caving and the single-wheel sequential coal caving also disturb the top plate, the influence of the single-wheel interval coal caving and the single-wheel sequential coal caving on the top plate is limited, the control of the top plate of a stope is facilitated, and meanwhile, the top coal caving rate of the single-wheel sequential coal caving is higher than that of the single-wheel interval coal caving, so that the top coal caving mode determines and selects the single-wheel sequential coal caving mode in terms of a coal bed with a large inclination angle.

For a coal seam with a large inclination angle, taking a coal seam inclination angle of 35 degrees as an example, the influence of coal caving from top to bottom and coal caving from bottom to top on the recovery rate is analyzed. It can be known from simulation that, at the same coal seam inclination angle, the recovery rate of coal caving from bottom to top is 82.5%, while the recovery rate of coal caving from top to bottom is 83.1% higher than that of coal caving from bottom to top, and although the influence of coal caving from top to bottom on the roof is greater than that of coal caving from bottom to top, the influence range is smaller, so from the viewpoint of economic benefit, when coal is caving at a large inclination angle, the coal caving from top to bottom is recommended.

The invention has been applied to the Pompe tower coal mine 9 of Huo State coal and electricity group^#The coal bed obtains good effect.

Pozhou coal and electricity group colongpo tower coal mine 9^#The coal layer is arranged at the middle lower part of the Taiyuan group with the upper distance of 5^#The coal seam is 40.90-56.15 m, and the average is 50.63 m. The thickness of the coal seam is 10.8-12.4 m, the average thickness is 11.8m, the dip angle is 4-34 degrees, the Poulean coefficient f is 1, the coal seam belongs to a large dip angle soft extra-thick coal seam, the structure of the coal seam is complex, the coal seam generally comprises 1-4 layers of sandwiched waste rocks, the thickness of the sandwiched waste rocks is 0.10-0.38 m, and most of the sandwiched waste rocks are carbon mudstones. 9^#The coal bed is directly topped by argillaceous limestone, irregular cracks and oblique cracks develop, most of the coal bed is filled with calcite, animal fossil such as shells and the like is contained, a thin layer of the argillaceous limestone is sandwiched, and the average thickness is 6.7 m; the false roof is carbon mudstone, gray and semi-hard, a small amount of black and semi-bright briquette is clamped in the middle, and the average thickness is 0.5 m; the direct bottom of the coal bed is mud rock, gray and massive, and the average thickness is 1.9 m; the old bottom is light gray fine sandstone, medium-thick lamellar, hard and semi-hard, vein-like lamellar, and has the average thickness of 2.0m, and the oblique fracture develops and is not filled. 9^#The coal seam is mined by adopting a fully-mechanized top coal caving one-time mining full-thickness strike longwall coal mining method, the mechanical mining height is 3.2m, the top coal caving thickness is 8.6m, coal is cut in a one-way mode, the coal is cut in one mining and one caving mode, a single-wheel sequential coal caving mode is adopted, the coal cutting step pitch is 0.8m, and the coal caving step pitch is 0.8 m.

The huge and numerous tower mining practices show that the problems of serious potential safety hazards of coal caving of lower supports in an area with a large inclination angle and coal emptying of 5-8 tops in the upper portion, low cycle yield and coal caving efficiency, unreasonable advanced support mode and range, equipment gliding and dumping, gangue flying of a face scraper conveyor and the like exist in the mining process of a large inclination angle soft and thick coal seam. The colossal tower coal mine accumulates abundant technology and management experience in the aspect of large dip angle soft thick coal seam comprehensive mechanized caving coal mining technology, the invention solves a plurality of technical problems in the colossal tower mine mining process, and the colossal tower coal mine mainly comprises the following aspects: firstly, the problem that the coal is discharged from the lower support and the upper part is 5-8 in the coal discharging process of the large-inclination area coal discharging process is solved^#The coal on the top of the frame is empty, so that serious potential safety hazards exist, the phenomenon of the coal on the top of the upper frame is controlled by adopting a small amount of coal discharge of the lower frame, the technical problem of serious waste of coal resources is caused, and the safety problem of operators is fully guaranteed; secondly, the coal caving efficiency and the coal recovery rate of the fully mechanized caving face are improved, and the dilution rate is reduced; thirdly, the cycle yield of the fully mechanized caving face is improved; fourthly, a reasonable advanced supporting mode of the fully mechanized caving face is provided; fifthly, the invention has reasonable design, simple technology and convenient construction, and the adopted stability control method of the coal wall of the working face and the fully mechanized caving mining safety precaution method can improve the stability of the coal wall of the working face, effectively ensure the safety problem of workers in the coal seam mining process and reduce the occurrence probability of safety accidentsAnd the safe and efficient production of the working face is realized. The method has important practical significance and great practical value for improving the coal recovery rate of fully mechanized caving mining of the soft and thick coal seam with large inclination angle, reducing the dilution rate and ensuring safe and efficient production of the mine. Since the technology of the invention is adopted in the colossal tower mine, the production safety accidents are reduced by 80 percent.

Other technical features than those described in the specification are known to those skilled in the art, and are not described herein in detail in order to highlight the innovative features of the present invention.

Claims

1. A large-inclination-angle fully-mechanized caving mining caving method comprises large-inclination-angle fully-mechanized caving mining top coal caving evaluation, a control method of large-inclination-angle working face fully-mechanized caving mining stability, determination of large-inclination-angle fully-mechanized caving mining reasonable caving step distance and determination of large-inclination-angle fully-mechanized caving mining reasonable caving mode, and is characterized in that:

2. The large-inclination fully-mechanized caving mining and coal caving method according to claim 1, wherein: the evaluation of the caving performance of the top coal in the large-dip-angle fully-mechanized caving mining comprises the steps of analyzing factors influencing the caving performance of the top coal, confirming evaluation functions of the factors influencing the caving performance of the top coal, and obtaining the category of the caving performance of the top coal of the evaluated coal seam block section by using a gray-fuzzy evaluation model;

3. The large-inclination fully-mechanized caving mining and coal caving method according to claim 1, wherein: the method for improving the stability of the bracket comprises the following specific control measures:

(7) installing anti-falling and anti-skid jacks, namely installing the anti-falling or anti-skid jacks on the hydraulic support and adjusting the jacks among the supports; the movable side guard plates are all arranged on the shield support.

4. The method for controlling the fully mechanized caving mining stability of the large-inclination-angle working face according to claim 1, wherein the method comprises the following steps: the method for controlling the stability of the coal wall of the working surface comprises the following specific control measures:

5. The method for controlling the fully mechanized caving mining stability of the large-inclination-angle working face according to claim 1, wherein the method comprises the following steps: the fully mechanized caving mining safety precaution method has the following specific control measures:

the working surface power cable is antiskid: all the other cables except the coal mining machine cable on the working surface are arranged in a forward sliding cable trough, and in order to prevent the cables from sliding downwards, hoisting belts are used for binding the cables and fixing the cables with the sliding trough every 10 m;

(5) antiskid method for scraper conveyor

6. The method for controlling the fully mechanized caving mining stability of the large-inclination-angle working face according to claim 1, wherein the method comprises the following steps: the method is used for underground mining coal mine with the average inclination angle of the coal seam of 20-30 degrees.

7. The method for controlling the fully mechanized caving mining stability of the large-inclination-angle working face according to claim 1, wherein the method comprises the following steps: the reasonable coal caving step pitch for the large-inclination fully mechanized caving mining is determined as follows: adopting a coal caving mode of one coal caving step (coal caving step pitch is 0.8 m).

8. The method for controlling the fully mechanized caving mining stability of the large-inclination-angle working face according to claim 1, wherein the method comprises the following steps: the reasonable coal caving mode of the large-inclination fully mechanized caving mining is determined as follows: coal is sequentially discharged in a single wheel mode from top to bottom.