CN111622773A - High-gas working face roadway structure, arrangement method and coal pillar width determination method thereof - Google Patents
High-gas working face roadway structure, arrangement method and coal pillar width determination method thereof Download PDFInfo
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- CN111622773A CN111622773A CN202010522678.1A CN202010522678A CN111622773A CN 111622773 A CN111622773 A CN 111622773A CN 202010522678 A CN202010522678 A CN 202010522678A CN 111622773 A CN111622773 A CN 111622773A
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- 239000003245 coal Substances 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 17
- 238000005065 mining Methods 0.000 claims abstract description 18
- 239000000463 material Substances 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 4
- 238000009826 distribution Methods 0.000 claims description 16
- 230000005641 tunneling Effects 0.000 claims description 5
- 238000013461 design Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000012856 packing Methods 0.000 claims description 2
- 239000011435 rock Substances 0.000 claims description 2
- 238000009412 basement excavation Methods 0.000 abstract description 6
- 239000002699 waste material Substances 0.000 abstract description 4
- 238000011084 recovery Methods 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/14—Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F1/00—Ventilation of mines or tunnels; Distribution of ventilating currents
- E21F1/006—Ventilation at the working face of galleries or tunnels
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F15/00—Methods or devices for placing filling-up materials in underground workings
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
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- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
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Abstract
The invention discloses a high gas working face roadway structure, an arrangement method and a coal pillar width determination method thereof, and relates to the technical field of stope face roadway arrangement. The multiple working faces of the tunnel structure are all provided with double U-shaped tunnels, in two adjacent working faces, the track air return tunnel of the previous working face is used as the gas discharge tunnel of the next working face, and the gas discharge tunnel of the previous working face is used as the air return tunnel of the next working face; and a high-water material roadside filling body is arranged on one side of the gas discharge lane of the next working face, which faces the upper working face. The roadway arrangement structure greatly reduces the roadway excavation amount of the face of taking over, relieves the shortage problem of mine excavation taking over, simultaneously recovers the left-over coal pillars of the face of first mining, increases economic benefits and avoids resource waste.
Description
Technical Field
The invention relates to the technical field of roadway arrangement of stope faces, in particular to a roadway structure of a high-gas longwall caving stope face, an arrangement method and a coal pillar width determination method thereof.
Background
Longwall caving coal is widely used in China due to its characteristics of large yield, high efficiency and low tunneling rate. However, in the longwall caving face, because of its high output per unit time, the associated gas relative emission is greatly increased, resulting in a high gas content in the upper corners and return airway of the coal face, which greatly jeopardizes the safe production of the coal face. The above problems are more serious in high gas coal mines.
In order to solve the problem of gas accumulation at the upper corner of the excavation face, double U-shaped roadways are often arranged in the prior art, and an internal U-shaped roadway and an external U-shaped roadway are communicated through a connecting roadway. After the excavation of two adjacent working faces is completed, the outer rail lane (outer transport lane) between the two working faces is left for ventilation and pedestrian passage.
However, in a double U-lane arrangement, the coal pillars between the outer rail lane (outer haulage lane) and the adjacent inner rail lane and inner haulage lane are typically set to a width of 25-35 m. The outer rail roadway (outer transportation roadway) in such a state is affected by two-time mining stress of the longwall working faces on two sides, the bearing state of the outer rail roadway is very complex, and the layout of the existing roadway is further affected.
Disclosure of Invention
According to the high-gas working face roadway structure provided by the invention, a plurality of working faces are uniformly provided with double U-shaped roadways, and in two adjacent working faces, the track air return roadway of the previous working face is used as the gas discharge roadway of the next working face, and the gas discharge roadway of the previous working face is used as the air return roadway of the next working face; and a high-water material roadside filling body is arranged on one side of the gas discharge lane of the next working face, which faces the upper working face.
The invention also discloses a method for arranging the high gas working face roadway, which comprises the following steps:
step one, arranging an initial working face, and tunneling a return airway and a gas discharge airway simultaneously.
Secondly, performing gob-side entry retaining on the return airway of the initial working face during the stoping period of the initial working face, and constructing a roadside filling body to form a gas discharge airway of the next working face; the gas discharge lane of the initial working face is used as the return air lane of the next working face.
And step three, after the recovery of the initial working face is finished and the overlying strata are stable, penetrating through the auxiliary cutting hole of the next working face to form a complete mining system.
And step four, repeating the step 2-3, arranging a plurality of working faces in a sequential succession mode, and mining coal until the working face roadway arrangement and the working face stoping of the whole mining area are completed.
The invention also discloses a method for determining the width of the coal pillars between the roadways of the working face, which comprises the following steps:
step one, calculating the area in an inelastic zone in the area formed between a vertical stress distribution shape curve above the coal pillar and an x axis when the stresses on the two sides of the coal pillar are not superposed:
step two, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis when the stresses on the two sides of the coal pillar are not superposed:
step three, calculating the area in the inelastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stresses on the two sides of the coal pillar are superposed:
step four, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stress at the two sides of the coal pillar is superposed:
step five, according to the area superposition principle S1+S2=S3+S4And solving and finishing the four formulas to obtain the width x of the inelastic zone of the coal pillarp。
Step six, combining the formula related to the nuclear zone rate in the coal pillar design, namelyAnd in actual production practice, the nuclear area rate needs to be more than 65% to keep the stability of the coal pillar, and the reasonable width of the coal pillar is calculated.
Compared with the prior art, the high gas working face roadway structure, the arrangement method and the coal pillar width determination method have the advantages that:
(1) the roadway arrangement structure greatly reduces the roadway excavation amount of the face of taking over, relieves the shortage problem of mine excavation taking over, simultaneously recovers the left-over coal pillars of the face of first mining, increases economic benefits and avoids resource waste.
(2) The invention provides a reasonable calculation method for the width of coal pillars between roadways, which avoids the waste of coal resources on the basis of ensuring the stability of the roadway structure.
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For a clearer explanation of the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for a person skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic diagram of a high gas working face roadway structure disclosed by the invention.
FIG. 2 is a graph of the vertical stress distribution of a coal pillar during one-sided mining.
FIG. 3 is a vertical stress distribution profile of a coal pillar during two-sided mining.
In the figure: 1-a previous working surface; 2-next working face; 3-a working face track return airway; 4-gas discharge lane of the previous working face; 5-gas discharge lane of next working face; 6-next working face return airway; 7-roadside packing elements; p-lateral bearing pressure applied to the edge of the coal pillar; gamma-overburden bulk density; h-coal seam burial depth; sigmaz-vertical stress.
Detailed Description
The following provides a brief description of embodiments of the present invention with reference to the accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the protection scope of the present invention.
Fig. 1-3 show preferred embodiments of the invention, which are each parsed in detail from different perspectives.
In order to reduce the tunneling and solve the problem of shortage of mining and taking over, in two adjacent working faces, the previous working face track return airway 3 is used as the next working face gas discharge airway 5, and in order to increase the recovery rate of coal, the previous working face gas discharge airway 4 is used as the next working face return airway 6, so that the left-over coal pillars of the previous working face 1 can be recovered. A high-water material roadside filling body 7 is arranged on one side of the gas discharge lane 5 of the next working face, which faces the previous working face 1, and the roadside filling body is constructed in a conventional manner, which is not described in detail herein.
The invention also discloses a method for arranging the high gas working face roadway, which comprises the following steps:
step one, arranging an initial working face, and tunneling a return airway and a gas discharge airway simultaneously.
Secondly, performing gob-side entry retaining on the return airway of the initial working face during the extraction of the initial working face, and constructing a roadside filling body to form a gas discharge airway 5 of the next working face; the gas discharge lane of the initial face is used as the next face return air lane 6.
And step three, after the recovery of the initial working face is finished and the overlying strata are stable, the next working face 2 is communicated for auxiliary hole cutting to form a complete mining system.
And step four, repeating the step 2-3, arranging a plurality of working faces in a sequential succession mode, and mining coal until the working face roadway arrangement and the working face stoping of the whole mining area are completed.
In the roadway arrangement mode disclosed by the invention, the bearing coal pillars in the first working face must be reasonably designed, and the width of the coal pillars is reduced as much as possible. If the coal pillar is too wide, waste of coal resources is caused. On the contrary, if the coal pillar is too narrow, the difficulty of maintaining the roadway is increased, and the service life of the roadway is further affected. Based on the method, in order to ensure the reasonable design of the width of the bearing coal pillar, the invention also discloses a method for determining the width of the coal pillar between the roadways of the working face. As shown in fig. 2 and 3, during the formation of the coal pillar, the coal pillar is subjected to the lateral supporting stress of the previous working face 1 on one hand and the lateral supporting stress of the next working face 2 on the other hand, and under the mining stress of the working faces at both sides, the vertical stress distribution form above the coal pillar is a double-peak form. Combining the vertical stress distribution form of the coal pillar, and by means of the area superposition principle, the specific calculation method comprises the following steps:
step one, calculating the area in an inelastic zone in the area formed between a vertical stress distribution shape curve above the coal pillar and an x axis when the stresses on the two sides of the coal pillar are not superposed:
wherein: a is half of the length of a coal face; b is half of the mining height of the coal face; r is the distance between the research point and the surrounding rock of the section of the coal face; r0 refers to the inelastic zone width of the coal pillar;refers to the residual uniaxial compressive strength of the coal; f. of1The coefficient of friction between the coal pillar and the top and bottom plates is referred to;refers to the internal friction angle of the coal; m0Refers to the softening modulus of the coal; stRefers to the strain gradient of the coal in the plastic zone; r1 refers to the loose width of the coal pillar.
Step two, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis when the stresses on the two sides of the coal pillar are not superposed:
wherein: a is half of the length of a coal face; r0 refers to the inelastic zone width of the coal pillar; q is the vertical pressure applied to the coal seam by the overlying strata; and B refers to the width of the coal pillar.
Step three, calculating the area in the inelastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stresses on the two sides of the coal pillar are superposed:
wherein: p refers to the lateral bearing pressure applied to the edge of the coal pillar;refers to the residual uniaxial compressive strength of the coal; x is the number ofpRefers to the inelastic zone width of the coal pillar.
Step four, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stress at the two sides of the coal pillar is superposed:
wherein: b refers to the width of the coal pillar; r0 refers to the inelastic zone width of the coal pillar.
Step five, according to the area superposition principle S1+S2=S3+S4And solving and finishing the four formulas to obtain the width x of the inelastic zone of the coal pillarp。
Step six, combining the formula related to the nuclear zone rate in the coal pillar design, namelyAnd in actual production practice, the nuclear area rate needs to be more than 65% to keep the stability of the coal pillar, and the reasonable width of the coal pillar is calculated.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (3)
1. A high gas working face roadway structure is characterized in that a plurality of working faces are all provided with double U-shaped roadways, in two adjacent working faces, a previous working face track air return roadway (3) is used as a next working face gas discharge roadway (5), and a previous working face gas discharge roadway (4) is used as a next working face air return roadway (6); a high-water material roadside packing body (7) is arranged on one side of the gas discharge lane (5) of the next working face, which faces the upper working face (1).
2. A method of deploying a high gas face roadway as claimed in claim 1, comprising the steps of:
step one, arranging an initial working face, and tunneling a track return airway and a gas discharge airway simultaneously;
step two, during the stoping period of the initial working face, performing gob-side entry retaining on the rail return airway of the initial working face, and constructing a roadside filling body (7) to form a gas discharge airway (5) of the next working face; using the gas discharge lane of the initial working face as a return air lane (6) of the next working face;
thirdly, after the mining of the initial working face is finished and the overlying rock stratum is stable, the next working face (2) is communicated for auxiliary hole cutting to form a complete mining system;
and step four, repeating the step 2-3, arranging a plurality of working faces in a sequential succession mode, and mining coal until the working face roadway arrangement and the working face stoping of the whole mining area are completed.
3. The method for determining the width of a coal pillar between high gas face roadways as claimed in claim 1, comprising the steps of:
step one, calculating the area in an inelastic zone in the area formed between a vertical stress distribution shape curve above the coal pillar and an x axis when the stresses on the two sides of the coal pillar are not superposed:
step two, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis when the stresses on the two sides of the coal pillar are not superposed:
step three, calculating the area in the inelastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stresses on the two sides of the coal pillar are superposed:
step four, calculating the area in the elastic zone in the area formed between the vertical stress distribution shape curve above the coal pillar and the x axis after the stress at the two sides of the coal pillar is superposed:
step five, according to the area superposition principle S1+S2=S3+S4And solving and finishing the four formulas to obtain the width x of the inelastic zone of the coal pillarp;
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113153435A (en) * | 2021-05-17 | 2021-07-23 | 中国矿业大学 | Method for determining coal pillar reinforcement parameters under double-roadway arrangement system re-mining disturbance |
CN114329892A (en) * | 2021-11-26 | 2022-04-12 | 中国矿业大学 | Method for determining width of coal pillar of stope face section of high-impact self-igniting coal seam |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101871356A (en) * | 2010-01-30 | 2010-10-27 | 山西晋城无烟煤矿业集团有限责任公司 | U+H type ventilation system |
CN102587960A (en) * | 2012-03-22 | 2012-07-18 | 中国矿业大学 | Arrangement method of high gas coal seam extraction working face roadway |
CN103603673A (en) * | 2013-11-22 | 2014-02-26 | 山西晋城无烟煤矿业集团有限责任公司 | Stope face parallel dual-U-type roadway |
CN104179520A (en) * | 2014-08-26 | 2014-12-03 | 山西潞安环保能源开发股份有限公司 | Z-shaped ventilation method and system for gob-side entry of coalface |
CN106223996A (en) * | 2016-09-14 | 2016-12-14 | 煤科集团沈阳研究院有限公司 | Super-large diameter coal bed drilling intubates extraction goaf gas technique |
CN108505999A (en) * | 2018-03-21 | 2018-09-07 | 六盘水师范学院 | A kind of high prominent more lane method for arranging of working face of coal seam |
CN207847676U (en) * | 2017-12-28 | 2018-09-11 | 山西晋城无烟煤矿业集团有限责任公司 | A kind of high prominent U-shaped ventilating system of mine coal-cutting working face |
-
2020
- 2020-06-10 CN CN202010522678.1A patent/CN111622773A/en active Pending
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101871356A (en) * | 2010-01-30 | 2010-10-27 | 山西晋城无烟煤矿业集团有限责任公司 | U+H type ventilation system |
CN102587960A (en) * | 2012-03-22 | 2012-07-18 | 中国矿业大学 | Arrangement method of high gas coal seam extraction working face roadway |
CN103603673A (en) * | 2013-11-22 | 2014-02-26 | 山西晋城无烟煤矿业集团有限责任公司 | Stope face parallel dual-U-type roadway |
CN104179520A (en) * | 2014-08-26 | 2014-12-03 | 山西潞安环保能源开发股份有限公司 | Z-shaped ventilation method and system for gob-side entry of coalface |
CN106223996A (en) * | 2016-09-14 | 2016-12-14 | 煤科集团沈阳研究院有限公司 | Super-large diameter coal bed drilling intubates extraction goaf gas technique |
CN207847676U (en) * | 2017-12-28 | 2018-09-11 | 山西晋城无烟煤矿业集团有限责任公司 | A kind of high prominent U-shaped ventilating system of mine coal-cutting working face |
CN108505999A (en) * | 2018-03-21 | 2018-09-07 | 六盘水师范学院 | A kind of high prominent more lane method for arranging of working face of coal seam |
Non-Patent Citations (1)
Title |
---|
闫帅等: "复用回采巷道护巷煤柱合理宽度研究", 《岩土力学》 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113153435A (en) * | 2021-05-17 | 2021-07-23 | 中国矿业大学 | Method for determining coal pillar reinforcement parameters under double-roadway arrangement system re-mining disturbance |
CN114329892A (en) * | 2021-11-26 | 2022-04-12 | 中国矿业大学 | Method for determining width of coal pillar of stope face section of high-impact self-igniting coal seam |
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