阅读说明：本技术 一种源头减弱采动地裂缝发育的煤柱间隔错式工作面布局方法 (Coal pillar interval staggered working face layout method for weakening mining ground crack growth from source ) 是由 朱恒忠 陈绍杰 臧传伟 尹大伟 张广超 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种源头减弱采动地裂缝发育的煤柱间隔错式工作面布局方法,其包括以下步骤：步骤1.确定所要开采区域的上煤层工作面、下煤层工作面的整体布局形式；步骤2.确定上煤层工作面、下煤层工作面采用的采煤方法、采煤工艺、巷道布置、采空区处理方法、工作面走向长度、工作面倾向长度、采高；步骤3.确定间隔煤柱宽度；步骤4.构建实质反映上煤层工作面、下煤层工作面生产地质条件的数值模拟计算模型以及监测获取煤层开采过程中的地表沉陷数据,并绘制地表沉陷曲线；步骤5.根据工作面布局方式,确定上煤层工作面、下煤层工作面的开采顺序,形成采煤系统、掘进系统、运输系统、通风系统、排水系统。(The invention discloses a coal pillar interval staggered type working face layout method for weakening mining ground crack development from a source, which comprises the following steps: step 1, determining the overall layout form of an upper coal seam working face and a lower coal seam working face of an area to be mined; step 2, determining a coal mining method, a coal mining process, roadway arrangement, a goaf treatment method, a working face strike length, a working face inclination length and a mining height adopted by an upper coal seam working face and a lower coal seam working face; step 3, determining the width of the coal pillars at intervals; step 4, constructing a numerical simulation calculation model which substantially reflects the geological conditions of the working surface of the upper coal seam and the working surface of the lower coal seam, monitoring and acquiring surface subsidence data in the coal seam mining process, and drawing a surface subsidence curve; and 5, determining the mining sequence of the working face of the upper coal seam and the working face of the lower coal seam according to the layout mode of the working faces to form a coal mining system, a tunneling system, a transportation system, a ventilation system and a drainage system.)

1. A coal pillar interval staggered working face layout method for weakening mining ground crack development from a source is characterized in that: which comprises the following steps:

step 1, determining the overall layout form of an upper coal seam working face (5) and a lower coal seam working face (4) of a region to be mined according to the development condition of a coal seam, the geological structure, the hydrogeology, the gas and the coal dust production geological conditions and by combining a mining engineering plan and an underground comparison map;

step 2, determining a coal mining method, a coal mining process, roadway arrangement, a goaf processing method, a working face strike length, a working face inclination length and a mining height adopted by an upper coal seam working face (5) and a lower coal seam working face (4) by combining mine mining design specifications;

step 3, determining the width of the coal pillars at intervals;

step 4, according to the overall layout mode of the upper coal seam working face (5) and the lower coal seam working face (4), adopting numerical simulation and theoretical calculation means, combining the production geological conditions of the upper coal seam working face and the lower coal seam working face and the rock stratum physical and mechanical parameters, constructing a numerical simulation calculation model which substantially reflects the production geological conditions of the upper coal seam working face (5) and the lower coal seam working face (4), monitoring and acquiring surface subsidence data in the coal seam mining process, and drawing a surface subsidence curve;

and 5, determining the mining sequence of the upper coal seam working face (5) and the lower coal seam working face (4) according to the working face layout mode to form a coal mining system, a tunneling system, a transportation system, a ventilation system and a drainage system.

2. The coal pillar staggered working face layout method for source weakening mining ground fracture development according to claim 1, characterized in that: in the step 1, two overall layout forms are included: the coal pillar interval outer staggered mode and the coal pillar interval inner staggered mode; the coal pillar interval outer staggered type and the coal pillar interval inner staggered type are in reverse arrangement.

3. The coal pillar staggered working face layout method for source weakening mining ground fracture development as claimed in claim 2, characterized in that: in the coal pillar interval stagger mode,

the inclined length of the upper coal seam working face (5) is smaller than that of the lower coal seam working face (4);

the upper coal seam is divided into a section; the lower coal seam arrangement working surface is divided into two sections, and a first section (6) of the lower coal seam working surface and a second section (7) of the lower coal seam working surface are correspondingly arranged respectively;

a coal layer separating pillar (8) is left between the first section (6) of the working surface of the lower coal layer and the second section (7) of the working surface of the lower coal layer;

and the two ends of the first section (6) of the working surface of the lower coal seam and the second section (7) of the working surface of the lower coal seam are staggered with the working surface (5) of the upper coal seam.

4. The coal pillar staggered working face layout method for source weakening mining ground fracture development as claimed in claim 2, characterized in that: in the coal pillar interval internal staggering mode,

the inclined length of the upper coal seam working face (5) is greater than that of the lower coal seam working face (4);

the upper coal seam arrangement working face is divided into two sections, and a first section (1) of the upper coal seam working face and a second section (2) of the upper coal seam working face are correspondingly arranged respectively; the lower coal seam is arranged on a working surface and is divided into a section;

a coalbed separation coal pillar (3) is reserved between the first section (1) of the upper coalbed working surface and the second section (2) of the upper coalbed working surface;

and the two ends of the lower coal seam working face (4) are staggered with the upper coal seam working face (5).

5. The coal pillar staggered working face layout method for source weakening mining ground fracture development according to claim 3, characterized in that: in the step 3, the step of processing the image,

according to a working face layout mode, establishing a numerical calculation model by taking the occurrence and production geological conditions of the coal bed and the physical and mechanical parameters of the rock stratum as basic data, and researching and analyzing the stress distribution when the widths of the coal pillars at different intervals are different;

according to the stress distribution characteristics, the reasonable value of the width of the coal pillar at the interval is determined according to the principle of resource saving, safety, high efficiency and long-term smoothness of the roadway.

6. The coal pillar staggered working face layout method for source weakening mining ground fracture development according to claim 5, characterized in that: further comprising:

and determining the width of the coal pillar by theoretical calculation by adopting a coal pillar width calculation expression, and determining the final value of the width of the spaced coal pillar by combining a numerical simulation result.

Technical Field

The invention belongs to the field of mining damage and ecological restoration, and particularly relates to a coal pillar staggered-spacing type working face layout method for weakening mining ground crack development from a source.

Background

The mining ground crack is a typical mine geological disaster induced by coal seam mining and is the concrete embodiment of the comprehensive action of underground coal seam mining disturbance and surface movement deformation. Disasters such as landslide and dangerous rock collapse induced by mining ground cracks become the scientific and technological frontier of the science of disaster prevention and reduction and ecological environment protection in mining engineering and the outstanding difficult problems to be solved urgently.

At present, the treatment measures about the mining ground cracks are mainly divided into three types: first, surface backfill. For example, a water and soil conservation method (CN 105453977A) for promoting the vegetation recovery of the mining ground surface fissure zone in a mining area, proposes to fill the fissure → measure the vegetation degradation area on the two sides of the fissure → determine the vegetation planting quantity → form the vegetation green zone; a repairing method (CN 107461196B) for the step-shaped collapse of a coal mine is used for flaring, backfilling and grouting a root crack of the step-shaped collapse, so that the slope correction and the landfill treatment of the step-shaped collapse are realized. Second, the filling method. A high-water material ground fissure filling system and a filling treatment method (CN 103321228B) are provided, wherein the filling system is used for injecting high-water materials into fissures, and soil covering and tamping are carried out to carry out vegetation greening. Based on a fully mechanized coal gangue synchronous filling system and method (CN 109184784A) for reducing coal mining collapse degree, a method for synchronously filling coal gangue into a goaf by using a self-moving fully mechanized hydraulic support while mining coal is realized. Thirdly, leveling method. An emergency treatment method (CN 111946391A) for the ground deformation of a mountain coal mine divides a deformation area of a slope into an upper traction area, a middle sinking area and a lower pushing area according to the movement form of the slope deformation of the mountain. The blocking grooves are dug in transition zones of the upper traction area and the middle sinking area, so that the collapsed soil body in the upper traction area is blocked, the transmission and deformation direction of the soil body force are cut off, and time is gained for emergency treatment. A crack collapse land leveling method (CN 110984119A) divides a crack into a leveling crack and a slab staggering crack, excavates a surface soil layer on two sides of the leveling crack or on the lower side of the slab staggering crack, then fills an impermeable material to form an impermeable layer, and fills original soil to form a covering layer.

Therefore, the method for treating or weakening the mining ground fissure is basically developed by methods such as filling, grouting, leveling and the like, and the method is essentially a post-remedial measure after the mining ground fissure develops and cannot fundamentally solve the problem. The traditional method has the following defects and shortcomings:

(1) the mining ground crack treatment method is a post-remedial measure, and essentially is that the scale and the scale of the mining ground crack development cannot be weakened by carrying out manual modification on the mining ground crack on the basis of the mining ground crack development;

(2) filling, grouting and earthing all need more people and properties, and the process is many, the cycle is long, can cause secondary artificial disturbance to the mining ground crack surrounding environment. In addition, the application of the methods has certain limitations, and the methods are difficult to be applied to areas such as mountainous areas, hills and the like, which have large surface fluctuation changes and are inconvenient to traffic, and engineering implementation places are difficult to walk.

The essence of mining ground crack development is that the ground surface moving deformation caused by coal seam mining exceeds the strength of the surface soil layer, and further the surface soil layer is damaged. Therefore, to reduce the development of mining fractures, it is desirable to control the surface movement deformation caused by coal mining. The essential factors of the ground surface movement deformation are the underground working surface layout method and the coal mining process. Therefore, the method for weakening the development of the mining ground fracture from the source of the underground working face layout method and the coal mining process is an important problem to be solved urgently at present. Therefore, a new method for weakening the development of mining ground cracks by using a source head is urgently needed, and the method has great significance for the construction of green mines.

Disclosure of Invention

In order to achieve the purpose, the invention provides the following technical scheme: a coal pillar interval staggered working face layout method for weakening mining ground fracture development from a source comprises the following steps:

step 1, determining the overall layout form of an upper coal seam working face and a lower coal seam working face of a region to be mined according to the development condition of a coal seam, the geological structure, the hydrogeology, the gas and the coal dust production geological condition and by combining a mining engineering plan and an underground comparison map;

step 2, determining a coal mining method, a coal mining process, roadway arrangement, a goaf processing method, a working face strike length, a working face inclination length and a mining height adopted by an upper coal seam working face and a lower coal seam working face by combining mine mining design specifications;

step 3, determining the width of the coal pillars at intervals;

step 4, according to the overall layout mode of the working surface of the upper coal seam and the working surface of the lower coal seam, adopting numerical simulation and theoretical calculation means, combining the production geological conditions of the working surface of the upper coal seam and the working surface of the lower coal seam and the physical and mechanical parameters of rock strata, constructing a numerical simulation calculation model which substantially reflects the production geological conditions of the working surface of the upper coal seam and the working surface of the lower coal seam, monitoring and acquiring surface subsidence data in the coal seam mining process, and drawing a surface subsidence curve;

and 5, determining the mining sequence of the working face of the upper coal seam and the working face of the lower coal seam according to the layout mode of the working faces to form a coal mining system, a tunneling system, a transportation system, a ventilation system and a drainage system.

Further, step 1 preferably includes two overall layout forms: the coal pillar interval outer staggered mode and the coal pillar interval inner staggered mode; the coal pillar interval outer staggered type and the coal pillar interval inner staggered type are in reverse arrangement.

Further, preferably, in the coal pillar interval stagger formula,

the inclined length of the working surface of the upper coal seam is smaller than that of the working surface of the lower coal seam;

the upper coal seam is divided into a section; the lower coal seam arrangement working face is divided into two sections, and a first section of the lower coal seam working face and a second section of the lower coal seam working face are correspondingly arranged respectively;

a coal layer separating pillar is arranged between the first section of the working surface of the lower coal layer and the second section of the working surface of the lower coal layer;

and the two ends of the first section of the working surface of the lower coal seam and the second section of the working surface of the lower coal seam are staggered with the working surface of the upper coal seam.

Further, preferably, in the coal pillar interval stagger formula,

the inclined length of the working surface of the upper coal seam is greater than that of the working surface of the lower coal seam;

the upper coal seam arrangement working face is divided into two sections, and a first section of the upper coal seam working face and a second section of the upper coal seam working face are correspondingly arranged respectively; the lower coal seam is arranged on a working surface and is divided into a section;

a coalbed separation coal pillar is left between the first section of the upper coalbed working surface and the second section of the upper coalbed working surface;

and the two ends of the working surface of the lower coal seam are staggered with the working surface of the upper coal seam.

Further, preferably, in the step 3,

according to a working face layout mode, establishing a numerical calculation model by taking the occurrence and production geological conditions of the coal bed and the physical and mechanical parameters of the rock stratum as basic data, and researching and analyzing the stress distribution when the widths of the coal pillars at different intervals are different;

according to the stress distribution characteristics, the reasonable value of the width of the coal pillar at the interval is determined according to the principle of resource saving, safety, high efficiency and long-term smoothness of the roadway.

Further, preferably, the method further comprises:

and determining the width of the coal pillar by theoretical calculation by adopting a coal pillar width calculation expression, and determining the final value of the width of the spaced coal pillar by combining a numerical simulation result.

Compared with the prior art, the invention has the beneficial effects that:

(1) compare the traditional overall arrangement mode of working face, through the reasonable layout coal seam working face, lower coal seam working face and confirm interval coal pillar width, the surface subsidence coefficient is dropped to 0.6 ~ 0.7 by 0.95 ~ 1, and the surface subsidence degree is showing and is weakening, and the surface subsidence curve is more gentle, and the surface subsidence volume is showing and is reducing. The working face coal pillar interval staggered layout method obviously weakens the degree of ground surface damage and weakens the scale and dimension of ground fracture development at the source.

(2) Different from the traditional method, the working face coal pillar interval staggered layout method is a fundamental measure, extra human and property are not needed, the ground crack treatment cost is obviously reduced by formulating a working face layout scheme and a mining design scheme, and the method has good social and environmental benefits and has important practical significance for the current green mine construction.

Drawings

FIG. 1 is a schematic diagram of a staggered arrangement of coal pillars on a working face;

FIG. 2 is a schematic diagram of a staggered arrangement of coal pillars on a working face;

FIG. 3 is a schematic view of a staggered arrangement of coal pillars on the working face of coal seam No. 8 and coal seam No. 9 of a mine;

FIG. 4 is a vertical stress distribution graph of different widths of coal pillars spaced on the working surface of No. 9 coal seam of a certain mine;

FIG. 5 is a schematic view of a coal pillar load distribution;

FIG. 6 is a numerical simulation calculation model of a working face coal pillar spacing disclination for a coal seam No. 8 and a coal seam No. 9 of a mine;

FIG. 7 is a plot of the vertical displacement of the earth's surface after mining of the working faces of coal seam No. 8 and coal seam No. 9 of a mine;

FIG. 8 is a plot of the horizontal displacement of the surface of a coal seam 8 and a coal seam 9 after mining of the working face of the mine;

in the figure: 1-first section of working surface of upper coal bed; 2-second section of working surface of coal layer; 3, separating coal pillars between coalbeds; 4-coal seam working face; 5, coal layer working surface; 6-the first section of the working surface of the lower coal seam; 7-second section of working surface of coal seam; and 8, arranging coal pillars between coal layers.

Detailed Description

In the embodiment of the invention, a coal pillar interval staggered type working face layout method for weakening mining ground crack development from a source comprises the following steps:

step 1, determining the overall layout form of an upper coal seam working face 5 and a lower coal seam working face 4 of a region to be mined according to the development condition of a coal seam, the geological structure, the hydrogeology, the gas and the coal dust production geological condition and by combining a mining engineering plan and an underground comparison map;

step 2, determining a coal mining method, a coal mining process, roadway arrangement, a goaf processing method, a working face strike length, a working face inclination length, high mining and the like adopted by an upper coal seam working face 5 and a lower coal seam working face 4 by combining mine mining design specifications;

step 3, determining the width of the coal pillars at intervals;

step 4, according to the overall layout mode of the upper coal seam working face 5 and the lower coal seam working face 4, adopting numerical simulation and theoretical calculation means, combining the production geological conditions of the upper coal seam working face and the lower coal seam working face and the physical and mechanical parameters of rock strata, constructing a numerical simulation calculation model which substantially reflects the production geological conditions of the upper coal seam working face 5 and the lower coal seam working face 4, monitoring and acquiring surface subsidence data in the coal seam mining process, and drawing a surface subsidence curve;

and 5, determining the mining sequence of the upper coal seam working face 5 and the lower coal seam working face 4 according to the working face layout mode to form a coal mining system, a tunneling system, a transportation system, a ventilation system, a drainage system and the like.

In this embodiment, step 1 includes two overall layout forms: the coal pillar interval outer staggered mode and the coal pillar interval inner staggered mode; the coal pillar interval outer staggered type and the coal pillar interval inner staggered type are in reverse arrangement.

Referring to fig. 2, as a preferred embodiment, in the coal pillar spacing stagger mode,

the inclined length of the upper coal seam working face 5 is smaller than that of the lower coal seam working face 4;

the upper coal seam is divided into a section; the lower coal seam arrangement working surface is divided into two sections, and a first section 6 of the lower coal seam working surface and a second section 7 of the lower coal seam working surface are correspondingly arranged respectively;

a lower coal seam spacing coal pillar 8 is reserved between the first section 6 of the lower coal seam working surface and the second section 7 of the lower coal seam working surface;

and the two ends of the first section 6 of the working surface of the lower coal seam and the second section 7 of the working surface of the lower coal seam are staggered with the working surface 5 of the upper coal seam.

Referring to fig. 1, in the present embodiment, in the coal pillar interval staggering manner,

the inclined length of the upper coal seam working face 5 is greater than that of the lower coal seam working face 4;

the upper coal seam arrangement working face is divided into two sections, and a first section 1 of the upper coal seam working face and a second section 2 of the upper coal seam working face are correspondingly arranged respectively; the lower coal seam is arranged on a working surface and is divided into a section;

a coalbed separation coal pillar 3 is left between the first section 1 of the upper coalbed working surface and the second section 2 of the upper coalbed working surface;

and both ends of the lower coal seam face 4 are staggered with the upper coal seam face 5.

In this embodiment, in the step 3,

according to a working face layout mode, establishing a numerical calculation model by taking the occurrence and production geological conditions of the coal bed and the physical and mechanical parameters of the rock stratum as basic data, and researching and analyzing the stress distribution when the widths of the coal pillars at different intervals are different;

according to the stress distribution characteristics, the reasonable value of the width of the coal pillar at the interval is determined according to the principle of resource saving, safety, high efficiency and long-term smoothness of the roadway.

In this embodiment, the method further includes:

the width of the coal pillar is determined by theoretical calculation by adopting a coal pillar width calculation expression, and the final value of the width of the coal pillar at intervals is determined by combining a numerical simulation result, so that the limitation of a single research means is made up, and the accuracy and the reliability of the result are improved.

The specific embodiment is as follows: a coal seam No. 8 and a coal seam No. 9 are mined from a certain mine, the thickness of the coal seam is 2.2m and 2.0m respectively, the inclination angle of the coal seam is 3 degrees, and the coal seam is a nearly horizontal coal seam. The interlayer spacing was 18 m. The No. 9 coal seam bottom plate is silty argillite, clayey siltstone and fine sandstone, and the top plate is gray argillite, clayey siltstone, limestone, silty argillite and medium fine sandstone; no. 8 coal seam has bottom plate of carbon claystone and top plate of limestone and fine sandstone.

Step 1): determining the overall layout form of the working surface

The well field of the mine is the west part of the dorsiflexion of great Weiling, the periphery of the well field is defined by four main fault limits of F1, F2, F3 and F5, the faults in the well field are rare, the main structure is a fold with large span and extremely wide and slow, the whole structure is a relatively stable monoclinic structure, and the structural complexity belongs to a simple type. The gas content of No. 8 coal bed is 9.45m³T; the content of No. 9 coal seam is 9.23m³And/t, managing according to coal and gas outburst mines. The spontaneous combustion tendencies of the identification results of the coal beds 8 and 9 are all three types, and belong to coal beds which are difficult to spontaneously combust. The karst fracture aquifer of the Changxing group and the stratified fracture aquifer of the quan group in the well field are direct water-filled aquifers of the mine. The hydrogeological exploration of well field belongs toMedium, etc. The explosiveness of 14 pieces of coal dust in the coal dust explosion test sample is tested, and the coal dust does not have explosion danger.

According to the production geological conditions, the working face mining sequence adopts descending mining, the No. 8 coal seam has coal and gas outburst danger, no coal pillar is required to be reserved, and the subsequent influence on the No. 9 coal seam mining is generated for avoiding the stress height concentration caused by the coal pillar. Therefore, the working surface of the No. 8 coal seam is divided into one section, the working surface of the No. 9 coal seam is divided into two sections, and the integral layout mode of the working surface is determined to be a working surface coal pillar interval outer staggering mode.

Step 2): determining face mining parameters

The coal mining method comprises the following steps: the coal mining method of the No. 8 coal seam and the No. 9 coal seam working face is a strike longwall retreating type coal mining method.

A goaf treatment method: and managing the top plate of the goaf by a total caving method.

③ the coal mining process: the coal mining process is fully mechanized mining, and the mining height of the No. 8 coal seam and the No. 9 coal seam is 1.8 m.

Working face inclination length: according to the coal bed and mining technical conditions of the mine, the inclined length of the working face of the No. 8 coal bed is determined to be 170m and the inclined length of the working face of the No. 9 coal bed is determined to be 120m by referring to similar condition data at home and abroad.

Arranging a tunnel: the return air ascending mountain of the mining area is arranged along the No. 8 coal seam, and the belt conveyor ascending mountain and the track ascending mountain are arranged on the No. 9 coal seam bottom plate. The working face roadway is arranged in a coal seam, and a centralized roadway is not arranged. The working face roadway is arranged in a single roadway, a U-shaped ventilation mode is adopted, and the roadway is ventilated once. And (5) hanging the center line in the roadway for construction so as to ensure the equal length of the working surface.

The tunnel communication mode: the connection mode between the rail climbing and the working face roadway adopts the form of adding a section rock gate to a train yard or adding a section connection inclined roadway to the train yard. The upper mountain of the rubber belt conveyor and the working face roadway adopt a coal chute connection mode. The return air goes up the mountain and is communicated with the working face roadway in an inclined roadway mode.

Supporting the roadway: the section of the working face roadway is rectangular, a combined supporting form of 'anchor net spraying and steel strips' is adopted, and the net section of the return airway is 10.2m²Cleaning of transportation laneThe section is 11.6m². And the air return roadway of the first section of the No. 9 coal seam working face and the transportation roadway of the second section are constructed along the boundary of the direction of the reserved coal pillars.

Step 3): determining the coal pillar spacing width between the first section and the second section of the No. 9 coal seam working surface

Referring to fig. 4, a UDEC numerical simulation calculation model is established according to the layout of working faces of coal seam No. 8 and coal seam No. 9, and vertical stress distributions with interval coal pillar widths of 8m, 11m, 15m, 17.8m, 26m and 40m are analyzed, as shown in fig. 4. It can be seen that the vertical stress is significantly reduced when the width of the coal pillar is 26-40 m. And determining the reasonable value range of the width of the spaced coal pillars to be 26-40 m.

In order to make up for the limitation of a single research means, the accuracy and the reliability of the result are improved. And (3) obtaining a coal pillar width value by theoretical calculation by adopting a coal pillar width calculation expression, and determining a final value of the width of the spaced coal pillars by combining a reasonable range of numerical simulation.

Referring to fig. 5, from the edge of the coal pillar to the deep part, a fracture zone i, a plastic zone ii and an elastic zone iii (fig. 5) generally appear, and the basic idea of the elastic core theory is that after the mining of the upper working face is completed for a period of time, the mechanical state of the coal pillar between the goaf and the roadway of the lower working face section should be an elastic core zone and plastic deformation zones on two sides, and the width of the elastic core zone should be more than or equal to twice the mining height of the coal bed.

Namely, it is

B≥2x₀+(1～2)m (2-1)

In the formula:

b, the theoretical width of the coal pillar;

x₀-pillar edge plastic zone width;

m is the height of the coal pillar;

width x of plastic zone at edge of coal pillar₀I.e. the distance between the bearing pressure and the edge of the coal body, using the theory of ultimate balance:

in the formula:

m represents the thickness of the coal bed;

f, friction coefficient of the coal bed and the top and bottom plates;

h, coal seam burial depth;

gamma-average volume weight of overlying strata of the coal bed;

c, coal bed cohesion;

-the internal angle of friction of the coal seam;

p_i-resistance of the support to the coal slope;

k is the stress concentration coefficient;

xi-triaxial stress coefficient of coal bed, equal to

According to the existing production geological data, the thickness of the No. 9 coal seam is 2.0m, the friction coefficient f between the coal seam and the top and bottom plates is 0.2, the average buried depth of the coal seam is 220m, and the average volume weight of the overlying rock stratum of the coal seam is 25KN/m³Coal cohesion C1.2 MPa and internal friction angleResistance p of support to coal side_iThe value of 0, the stress concentration coefficient k is 2.5, and the value of the triaxial stress coefficient xi of the coal seam is 2.11.

Obtaining the width x of the plastic zone of the mined-out coal body at one side according to the calculation formulas (2-1) and (2-2)₀The critical width of the formed stable coal pillar is 18.1m and is 38.2-40.2 m. And combining the numerical simulation result, the width of the interval coal pillar is 40 m.

Step 4): predicting the surface subsidence degree of the working surface of No. 8 coal seam and No. 9 coal seam after mining

Referring to fig. 6, 7 and 8, a UDEC numerical calculation model is established according to the staggered arrangement mode of the coal pillars of the working face of the coal seam No. 8 and the coal seam No. 9, and monitoring lines for acquiring surface subsidence data are arranged on the surface of the model.

Step 5): making a design plan of a production system

And determining that the mining sequence of the working faces of the No. 8 coal seam and the No. 9 coal seam is downward mining, wherein the mining sequence is No. 8 coal seam working face → the first section of the working face of the No. 9 coal seam → the second section of the working face of the No. 9 coal seam.

Raw coal transportation system: the raw coal produced by the No. 8 coal seam and the No. 9 coal seam stope face is transported to a shaft bottom coal bunker through a working face transportation lane, a section coal chute and a rubber belt conveyor, and then is transported to the ground through an inclined shaft rubber belt conveyor.

The auxiliary transportation system comprises: materials and equipment required by working faces of No. 8 coal seams and No. 9 coal seams enter a track goaf of a mining area from an auxiliary inclined shaft and a main roadway and are transported into the mining area through a track mountain and middle parking lot, a connection inclined roadway and a working face return airway; and the excavation coal of the No. 8 coal seam and the No. 9 coal seam working face roadway is gathered into the main coal system through the excavation rubber belt conveyor. Other excavated coal (gangue) is transported to the ground through a main roadway and an auxiliary inclined shaft by an auxiliary transportation system (the reverse direction of material transportation).

Ventilation system: : fresh air flow required by the working faces of the No. 8 coal seam and the No. 9 coal seam enters the auxiliary inclined shaft and the main inclined shaft from the ground and enters the working faces through a main roadway, a track descending hill, a middle parking lot, a connection inclined roadway and a transportation roadway. The ventilation air at the working face is discharged to the ground through a return air roadway, a return air connecting roadway, a return air ascending, a return air main roadway and a return air inclined shaft. Fourthly, a drainage system: no. 8 coal seam, No. 9 coal seam working face haulage roadway, return airway and tunnelling head all are equipped with the sewage pump. The water gushing on the stoping or driving working face is discharged to the upper mountain of the track through a self-flowing or sewage pump and then flows to the bottom sump through the large tunnel of the track. And finally, discharging to the ground through a main mine drainage pump.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and equivalent substitutions or changes according to the technical solution and the inventive concept of the present invention should be covered by the scope of the present invention.