Island attribute judgment method for longwall coal face

Abstract

The invention provides an island attribute judgment method for a longwall coal face, and relates to the technical field of coal mine ground pressure. The method specifically comprises the following steps: acquiring a mining engineering plan of a longwall coal face and selecting a longwall coal face to be analyzed; mining information of the longwall coal face to be analyzed is collected, and a working face arrangement diagram of the longwall coal face is drawn; judging whether the working face arrangement condition of the longwall coal face is typical working face arrangement or atypical working face arrangement; the longwall coal face arranged on the non-typical working face is typical, and equivalent typical working face arrangement of the longwall coal face is obtained; working face island attribute judgment is conducted on the long-wall coal face arranged on the typical working face and the equivalent typical working face of the long-wall coal face, the island attribute judgment result of the long-wall coal face is obtained, and judgment of the non-typical island working face under the conditions of the special-shaped working face and the special-shaped coal pillar is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine pressure, and in particular to a method for determining island attributes of a longwall coal mining working face. Background Art

[0002] my country's energy structure is dominated by coal, and the occurrence conditions of coal seams are complex and diverse. my country's coal mining technology is mainly longwall retreat mining, which inevitably causes the recovery of residual coal pillars at the end of the life of the mine or mining area, thus forming an isolated working face. In addition, in order to alleviate the tension of mining and excavation, reduce surface subsidence, and prevent and control coal seam spontaneous combustion and gas disasters, or to meet the requirements of special coal mining technology, some coal mines use "jump mining" to connect the working faces in the mining area, which inevitably leads to the formation of isolated working faces. Compared with ordinary working faces, isolated working faces have higher bearing pressure, and the stress concentration of its bearing pressure changes with the dynamic mining of the working face. When strong mine pressure appears, it often makes it difficult to maintain the working face mining tunnel, induces coal wall spalling and roof accidents, and even rock burst in severe cases. In addition, the threats of water, fire, gas, etc. in isolated working faces are more prominent than those in general working faces.

[0003] Due to its special geographical location and stress environment, the isolated working face often faces higher mining risks. In view of the potential threat that mining the isolated working face will pose to the safety of coal mines, special protective measures need to be taken when mining the isolated working face in coal mines. However, due to the large number of coal mines in my country, the complex and diverse geological conditions, the different shapes and occurrence states of the working faces, the existence of many special-shaped working faces and special-shaped coal pillars, and the lack of quantitative size standards for the width of the coal pillars of the working faces, the applicability of the existing typical isolated working face determination rules is controversial. In addition, since in engineering practice, one side of a working face is often separated from the goaf of other working faces by a coal pillar, there is no effective method to determine whether this side of the working face is a goaf. How to accurately determine the island attribute of a working face, that is, how to determine whether a working face is an isolated working face, is an important prerequisite for accurately taking corresponding technical measures and a handle for implementing relevant coal mine safety supervision policies. The traditional isolated working face determination method can only be used for the typical working face layout, and there is currently no method to determine the atypical working face layout. Therefore, it is urgent to develop a method for determining the island attributes of longwall coal mining faces in atypical island working face situations. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a method for determining the island attributes of a longwall coal mining working face, aiming to realize the determination of atypical island working faces in cases of irregular working faces and irregular coal pillars, and to provide technical support for accurately taking corresponding prevention and control technical measures.

[0005] The present invention proposes a method for determining the island attribute of a longwall coal mining working face, the method comprising the following steps:

[0006] Step S1: obtaining a mining engineering plan of a longwall coal mining face, and selecting a longwall coal mining face to be analyzed;

[0007] Step S2: collecting mining information of the longwall coal mining face to be analyzed, and drawing a working face layout diagram of the longwall coal mining face according to the mining information and the mining engineering plan of the longwall coal mining face;

[0008] Step S3: judging, according to the working face layout diagram of the longwall coal mining working face, whether the working face layout of the longwall coal mining working face is a typical working face layout or an atypical working face layout;

[0009] Step S4: typify the longwall coal mining working face with the atypical working face arrangement to obtain an equivalent typical working face arrangement of the longwall coal mining working face;

[0010] Step S5: determining the island attribute of the longwall coal mining working face based on the longwall coal mining working face with a typical working face arrangement and the equivalent typical working face of the longwall coal mining working face with an atypical working face arrangement, and obtaining the island attribute determination result of the longwall coal mining working face;

[0011] The four boundaries of the longwall coal mining working face are: the working face belt transport lane, the working face return air lane, the longwall coal mining working face opening eye and the working face stop mining line;

[0012] The mining information in step S2 includes: the structure, shape, range and size parameters of the longwall coal mining working face, and the position and range of the coal pillars adjacent to the longwall coal mining working face;

[0013] The method for determining the working face arrangement in step 3 is as follows: for any longwall coal mining working face, judging whether the longwall coal mining working face satisfies the following three conditions at the same time according to the mining information of the longwall coal mining working face, including:

[0014] Condition 1: The longwall coal mining face is a rectangular face;

[0015] Condition 2: There is no boundary fault between the longwall coal mining face and other solid coal areas other than the longwall coal mining face;

[0016] Condition 3: There are clearly identifiable goaf areas and solid coal areas on the four boundary sides of the longwall mining face;

[0017] If it is satisfied, the longwall coal mining working face is a typical working face; if it is not satisfied, the longwall coal mining working face is an atypical working face;

[0018] The clearly identifiable goaf area and solid coal area refer to: for a coal pillar adjacent to any boundary side of a longwall coal mining working face, if the coal pillar is a narrow and long coal pillar with a width of 0m-30m, then the longwall coal mining working face has a clearly identifiable goaf area on that side; if the minimum width of the coal pillar is greater than or equal to the dip length B of the longwall coal mining working face, then the longwall coal mining working face has a clearly identifiable solid coal area on that side;

[0019] The typical process described in step 4 includes:

[0020] Step A1: determine whether the longwall coal mining working face is a special-shaped working face. If not, do not perform equivalence on the longwall coal mining working face; if yes, perform equivalence on the longwall coal mining working face as a rectangular working face with a goaf behind the opening of the longwall coal mining working face;

[0021] The special-shaped working surface refers to a working surface with a triangular shape or a working surface with a trapezoidal shape;

[0022] Step A2: determining whether the longwall coal mining face contains a boundary fault, if not, not performing equivalence on the longwall coal mining face; if yes, performing equivalence on the side of the longwall coal mining face where the boundary fault is located as a goaf;

[0023] The situations where the longwall coal mining face contains boundary faults include: a boundary side of the longwall coal mining face is a boundary fault, a boundary fault exists at the opening of the longwall coal mining face, or a boundary fault exists on one side of the stop line of the longwall coal mining face;

[0024] Step A3: Determine whether there is a clearly identifiable goaf area or solid coal area in the longwall coal mining working face. If so, do not perform equivalent on the longwall coal mining working face. Otherwise, perform coal pillar size effect analysis on the side of the longwall coal mining working face where there is no clearly identifiable goaf area or solid coal area, and determine whether the side of the longwall coal mining working face is a solid coal area or a goaf area according to the analysis result.

[0025] The method for analyzing the size effect of coal pillars in the working face includes: microseismic analysis, support stress analysis, engineering analogy, physical simulation or numerical simulation;

[0026] For a longwall coal mining face without a clearly identifiable goaf or solid coal area, a method is selected from the above methods according to the mine conditions of the mine where the longwall coal mining face is located to perform a coal pillar size effect analysis on the side of the longwall coal mining face without a clearly identifiable goaf or solid coal area. The specific process is as follows:

[0027] If a microseismic monitoring system is deployed in the mine where the longwall coal mining face is located, the microseismic analysis method is selected to analyze the size effect of the coal pillar on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: for any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, the energy E generated by the coal pillar on this side within a certain period of time and the frequency and distribution of microseismic events on this side are counted. If the energy E on this side is ≥10 4 If the frequency of microseismic events on J accounts for less than 5% of the frequency of microseismic events occurring within the longwall coal mining face and within the coal pillars or goafs adjacent to the longwall coal mining face, then this side is a solid coal area; otherwise, this side is a goaf;

[0028] If the longwall coal mining face is equipped with a stress gauge, the support stress analysis method is selected to analyze the size effect of the coal pillar on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: the width of the lateral coal body plastic zone of the longwall coal mining face is calculated according to the limit equilibrium theory. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the sum of the widths of the two plastic zones, then this side is a solid coal area, otherwise this side is a goaf;

[0029] If there is a mining face with similar mining conditions to the longwall coal mining face, the engineering analogy method is selected to analyze the coal pillar size effect of the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: take the mining face with similar mining conditions to the longwall coal mining face as the analogy face, obtain the lateral support pressure or advance support pressure range of the analogy face, and determine the lateral support pressure or advance support pressure range of the longwall coal mining face according to the lateral support pressure or advance support pressure range of the analogy face. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf;

[0030] Similar mining conditions refer to: mining the same coal seam, the same coal seam thickness and coal seam inclination, and the same coal mining system and recovery process;

[0031] If the longwall coal mining face is not suitable for microseismic analysis, support stress analysis and engineering analogy, physical simulation or numerical simulation is used to analyze the coal pillar size effect on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area.

[0032] The physical simulation method is as follows: for a longwall coal mining face without a clearly identifiable goaf or solid coal area, a model of the longwall coal mining face is constructed according to the coal seam occurrence conditions of the longwall coal mining face, and a physical similarity simulation test is performed on the model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face without a clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on the side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then the side is a solid coal area, otherwise the side is a goaf;

[0033] The numerical simulation method is as follows: for a longwall coal mining face without an obviously identifiable goaf or solid coal area, a simulation model of the longwall coal mining face is constructed using numerical simulation software, and a numerical simulation test is performed on the simulation model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face without an obviously identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf area;

[0034] The width of the lateral coal body plastic zone of the longwall coal mining working face is expressed as:

[0035]

[0036] Where x0 represents the width of the lateral plastic zone of the coal body in the longwall mining face; M represents the thickness of the coal seam; λ represents the lateral pressure coefficient; represents the internal friction angle of the coal body; K represents the stress concentration coefficient; γHcosα represents the component of the original rock stress perpendicular to the coal seam direction when the inclination factor is considered; γH represents the original rock stress; γ represents the average bulk density of the overlying rock layer; H represents the burial depth of the coal seam; α represents the inclination of the coal seam; τ represents the cohesion of the coal body; N represents the supporting capacity of the coal wall;

[0037] The method for determining the island attribute of the working face is as follows: taking the longwall coal mining working face of the typical working face arrangement and the equivalent typical working face of the longwall coal mining working face of the atypical working face arrangement as the working face to be determined, and determining whether the working face to be determined meets the typical situation of the island working face, if so, the working face to be determined is an island working face; if not, the working face to be determined is a non-island working face;

[0038] Typical situations of the isolated island working face include: two-sided mining, three-sided mining and four-sided mining;

[0039] The two-sided goaf is a longwall coal mining face in which the outer sides of the belt transport lane and the return air lane of the working face are both goaf areas, and the rear of the cut eye and the outer side of the working face stop line are both solid coal areas;

[0040] The three-sided goaf is a longwall coal mining face, the working face belt transport lane and the working face return air lane outside are all goaf areas, and there is a longwall coal mining face behind the cut eye and outside the working face stop line with one side being a solid coal area and the other side being a goaf area;

[0041] The four-sided goaf refers to the longwall coal mining working face where the outside of the working face belt transport tunnel, the outside of the working face return air tunnel, the rear of the cutting eye and the outside of the working face stop mining line are all goaf areas.

[0042] The beneficial effects of adopting the above technical solution are:

[0043] Compared with the prior art, the method of the present invention converts the atypical working face layout into the typical working face layout through theoretical analysis and engineering analogy, and then uses the traditional island working face determination method to accurately determine the working face island attribute of the atypical working face layout. The method is easy to operate and easy to implement, and provides a powerful grip for coal mine safety supervision of atypical working face layout. For a working face with an atypical working face layout, if it is determined to be an island working face, targeted measures can be taken in advance to effectively avoid the occurrence of disasters such as coal wall spalling, rock burst, super mine pressure, and tunnel air leakage during the working face recovery process.

[0044] Compared with the prior art, the method of the present invention, by taking into account the superficial characteristics of the isolated working face "isolated in the sea of ​​coal" and the essential characteristics of "stress concentration", effectively solves the problem that the typical isolated working face determination method is not applicable due to the large number of coal mines in my country, complex and diverse geological conditions, different working face shapes and occurrence states, and the existence of a large number of special-shaped working faces and special-shaped coal pillars. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of a method for determining the island attribute of a longwall coal mining working face in this embodiment;

[0046] Figure 2 This is the layout diagram of the working surface 305 in this embodiment;

[0047] Figure 3 This is an equivalent typical working surface layout diagram of the working surface 305 in this embodiment. DETAILED DESCRIPTION

[0048] In order to facilitate the understanding of the present application, the specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0049] A method for determining the island attribute of a longwall coal mining face in this embodiment is as follows: Figure 1 As shown, the method comprises the following steps:

[0050] Step S1: Obtain a mining engineering plan of a longwall coal mining face, and select a longwall coal mining face to be analyzed.

[0051] In this embodiment, if Figure 2 As shown in the figure, the method used for coal resource recovery in my country is mainly longwall mining, which arranges many working faces in a certain mining coal seam, and there are section coal pillars, mining area coal pillars or large lane coal pillars between the working faces. The positions of working faces, lanes, and coal pillars and their relationship are drawn in the mining engineering plan, and each working face has its own number. Therefore, it is necessary to mark the longwall mining working face to be analyzed in the mining engineering plan.

[0052] Step S2: Collect mining information of the longwall coal mining face to be analyzed, and draw a working face layout diagram of the longwall coal mining face based on the mining information and the mining engineering plan of the longwall coal mining face.

[0053] The mining information includes: the structure, shape, range and size parameters of the longwall coal mining working face, and the position and range of the coal pillars adjacent to the longwall coal mining working face.

[0054] In this embodiment, the longwall coal mining face is defined by the face belt conveyor tunnel, the face return air tunnel, the cut eyes of the longwall coal mining face, and the face stop line. The structure of the longwall coal mining face refers to the faults within the face range and near the face boundary. Since the selected longwall coal mining face, that is, the mining face is generally rectangular, the rectangle mentioned here is not a rectangle in the strict sense, and a certain corner of the mining face may not necessarily be 90°, and there will be more or less deviations. Therefore, the selected longwall coal mining face's mining tunnel, including the face belt conveyor tunnel and the face return air tunnel, and the face stop line are used as boundaries to determine the goaf or coal pillar adjacent to the longwall coal mining face. That is, the mining tunnel and the face stop line of the longwall coal mining face are used as boundaries. There are four directions corresponding to the four sides of the rectangular face. In these four directions, the area adjacent to the longwall coal mining face is determined as the goaf or the unmined coal area, such as Figure 2 As shown, the goaf is filled with a gravel pattern, and the unmined coal area is represented by a slash.

[0055] In this embodiment, a certain mine is a high-gas, rock-burst mine with a certified production capacity of 2.0 Mt / a. It adopts vertical shaft development, and three blind inclined shafts for transportation, rails, and return air are extended. It adopts central parallel ventilation and negative pressure exhaust ventilation methods, with auxiliary shaft for air intake and main shaft for air return.

[0056] The 305 working face is selected as the longwall coal mining working face to be analyzed. The layout of the 305 working face is as follows: Figure 2 As shown. The 305 working face is located at the -770m level of the third mining area on the south wing of the mine, mining the II and III coal seams (combined layers), and the coal type is long flame coal. The surface elevation of the working face is +198.0~204.0m, the underground elevation is -648.4~-780.4m, and the mining depth is 854.4~978.4m. The working face has a dip length of 275m, a strike length of 285m, and a remaining mineable strike length of 200m. The coal seam is a monocline structure without folds. According to the exposure of coal roadway excavation, there is F 13 There are two normal faults, K1 and K2. The maximum drop of K1 fault is 2m, and the minimum drop is 2m; 13 The maximum drop of the fault is 6m and the minimum drop is 2m.

[0057] Step S3: According to the working face layout diagram of the longwall coal mining working face, it is determined whether the working face layout of the longwall coal mining working face is a typical working face layout or an atypical working face layout.

[0058] The method for determining the layout of the working face is as follows: for any longwall coal mining working face, judging whether the longwall coal mining working face satisfies the following three conditions at the same time according to the mining information of the longwall coal mining working face, including:

[0059] Condition 1: The longwall coal mining face is a rectangular face;

[0060] Condition 2: There is no boundary fault between the longwall coal mining face and other solid coal areas other than the longwall coal mining face;

[0061] Condition 3: There are clearly identifiable goaf areas and solid coal areas on the four boundary sides of the longwall mining face;

[0062] If it is satisfied, the longwall coal mining working face is a typical working face; if it is not satisfied, the longwall coal mining working face is an atypical working face.

[0063] The clearly identifiable goaf and solid coal area refer to: for the coal pillar adjacent to any boundary side of the longwall coal mining working face, if the coal pillar is a narrow long coal pillar with a width of 0m-30m, then there is a clearly identifiable goaf area on this side of the longwall coal mining working face; if the minimum width of the coal pillar is greater than or equal to the dip length B of the longwall coal mining working face, then there is a clearly identifiable solid coal area on this side of the longwall coal mining working face.

[0064] In this embodiment, the determination of the working face layout is based on the shape and size of the longwall coal mining working face, the structural distribution, and the shape and size effect of the coal pillars around the longwall coal mining working face. The typical working face layout should meet the following three characteristics at the same time: ① The longwall coal mining working face is a rectangular working face; ② There is no boundary fault around the longwall coal mining working face to separate the longwall coal mining working face from other solid coal areas; ③ The goaf and solid coal areas around the longwall coal mining working face can be clearly identified. According to the above definition of typical working face layout, if the layout of the working face does not meet the above three characteristics at the same time, the working face layout is an atypical working face layout. The periphery in feature ③ refers to the area in the four directions of the longwall coal mining working face with the mining roadway and the working face stop line as the boundary as the goaf area or the unmined coal area. If there is a roadway in the unmined coal area, the area is not interrupted. If the goaf encounters an unmined coal area, the goaf will be interrupted; if the unmined coal area encounters the goaf, the unmined coal area will be interrupted.

[0065] Step S4: Typing the longwall coal mining working face with the atypical working face arrangement to obtain an equivalent typical working face arrangement of the longwall coal mining working face.

[0066] In this embodiment, for longwall coal mining working faces with atypical working face layout, classification analysis is performed according to the fact that they do not meet the three characteristics of typical working face layout, and the atypical working face layout is typified according to the analysis results.

[0067] The typical process includes:

[0068] Step A1: Determine whether the longwall coal mining working face is an irregular working face. If not, do not perform equivalence on the longwall coal mining working face; if so, perform equivalence on the longwall coal mining working face as a rectangular working face with the goaf behind the opening of the longwall coal mining working face.

[0069] The special-shaped working surface refers to a working surface that is a triangle or a working surface that is a trapezoid.

[0070] In this embodiment, the longwall coal mining face refers to a whole coal mining face formed by the face belt transport lane, the face return air lane, the longwall coal mining face cut and the face stop coil, which is usually rectangular or trapezoidal. Generally speaking, the longwall coal mining face is rectangular, but the theoretical 90° cannot be achieved in engineering, and the strict rectangular requirement is not met. Some face cuts are short, and gradually become larger as the face advances, and look more like a triangle as a whole. The selected longwall coal mining face is a special-shaped face, and the face formation analysis is performed. Among them, the special-shaped face refers to a triangular face or a trapezoidal face that is not a rectangular face mentioned in the judgment conditions of the typical face arrangement. Since the formation of the triangular face and the trapezoidal face is due to the mining of residual coal pillars, and the back of the face cut is the goaf, it is equivalent to a rectangular face with the back of the cut as the goaf.

[0071] Step A2: Determine whether the longwall coal mining face contains a boundary fault. If not, do not perform equivalence on the longwall coal mining face; if so, treat the side of the longwall coal mining face where the boundary fault is located as the goaf.

[0072] The situations in which the longwall coal mining working face contains boundary faults include: a boundary side in the longwall coal mining working face is a boundary fault, there is a boundary fault at the opening of the longwall coal mining working face, or there is a boundary fault on one side of the stop line of the longwall coal mining working face.

[0073] In this embodiment, the boundaries of the four sides of the general longwall coal mining face are the working face belt transport lane, the working face return air lane, the longwall coal mining face opening and the working face stop line. The selected working face is demonstrated to contain a boundary fault, and the working face regional structural analysis is performed to analyze the distribution of faults in the selected working face area and its surroundings. If one side of the working face is a boundary fault, the working face opening position or the working face stop line has a boundary fault, then this side of the working face is equivalent to the goaf.

[0074] In this embodiment, the characteristics of the boundary fault include: the average fall is greater than 5m; the fault strike is consistent with the strike or inclination of the working face; the boundary fault is used as the basis for dividing the working face or dividing the boundary between the roadway layout and other areas. The other area here refers to the other side of the fault as other working faces or other mining areas / panels or non-mining areas.

[0075] Step A3: Determine whether there is a clearly identifiable goaf area or solid coal area in the longwall coal mining working face. If so, do not perform equivalence on the longwall coal mining working face. Otherwise, perform a working face coal pillar size effect analysis on the coal pillar on one side of the longwall coal mining working face where there is no clearly identifiable goaf area or solid coal area, and determine whether that side of the longwall coal mining working face is a solid coal area or a goaf area based on the analysis results.

[0076] In this embodiment, it is determined whether the goaf or solid coal area around the longwall coal mining face can be clearly identified, that is, whether the longwall coal mining face contains irregular coal pillars, and the size effect analysis of the coal pillars in the face is performed. The irregular coal pillars refer to the coal pillars around the longwall coal mining face that are not the coal pillars (body) mentioned in the typical face layout, such as the coal pillars in the face section are triangular, trapezoidal, irregular quadrilateral, polygonal (larger than quadrilateral), wide strip coal pillars, and wide strip coal pillars containing faults, and the width of the coal pillars is 30m to the dip length B. The coal pillar size effect analysis of the working face refers to judging whether the coal pillar on the side of the longwall coal mining working face where there are clearly identifiable goaf areas and solid coal areas can effectively reduce the stress concentration on that side of the longwall coal mining working face, and help bear the influence of the overlying rock pressure before the mining of the longwall coal mining working face and the increase in support pressure caused by the mining of the longwall coal mining working face. If so, then that side of the longwall coal mining working face is a solid coal area; otherwise, that side of the longwall coal mining working face is a goaf area.

[0077] The method for analyzing the size effect of coal pillars in the working face includes: microseismic analysis method, support stress analysis method, engineering analogy method, physical simulation method or numerical simulation method.

[0078] For a longwall coal mining face without a clearly identifiable goaf or solid coal area, a method is selected from the above methods according to the mine conditions of the mine where the longwall coal mining face is located to analyze the coal pillar size effect on the side of the longwall coal mining face without a clearly identifiable goaf or solid coal area. The specific process is as follows:

[0079] In this embodiment, since different mines have different conditions, it is necessary to select a suitable analysis method according to the mine's own conditions. If there is a microseismic monitoring system, the microseismic analysis method can be used; if a stress meter is installed on the working face, the support stress analysis method can be used; if there are similar mining working faces, the engineering analogy method can be used. If none of the above is available, a physical simulation experiment or a numerical simulation experiment is performed.

[0080] If a microseismic monitoring system is deployed in the mine where the longwall coal mining face is located, the microseismic analysis method is selected to analyze the size effect of the coal pillar on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: for any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, the energy E generated by the coal pillar on this side within a certain period of time and the frequency and distribution of microseismic events on this side are counted. If the energy E on this side is ≥10 4If the frequency of microseismic events of J accounts for less than 5% of the frequency of microseismic events occurring within the longwall coal mining working face and within the coal pillars or goafs adjacent to the longwall coal mining working face, then this side is a solid coal area; otherwise, this side is a goaf area.

[0081] In this embodiment, the process in which the longwall coal mining face and the coal pillars or goafs adjacent to the longwall coal mining face vibrate and release energy E due to coal rock damage within a certain period of time is called a microseismic event. When a microseismic event occurs, the microseismic monitoring system will calculate the three-dimensional coordinates of the location where the microseismic event occurs. The basic principle is that there are at least three receiving points to receive the vibration wave signal, and the location of the source of the vibration is determined based on the coordinates of the receiving points and the received vibration wave signals. By analyzing the energy E≥10 generated in the longwall coal mining face area and the nearby coal pillars or goafs within 6 months 4 The distribution of microseismic events of J on the working face layout diagram is used to determine the damage of the coal pillar. Figure 3 As shown in the figure, for the 305 working face, the energy E≥10 generated in the 305 working face and its surroundings in the past 6 months is statistically analyzed. 4 J, it was found that microseismic events mainly occurred in the 302 working face and the 305 working face, with 1615 and 1335 times respectively, accounting for 43.86% and 36.26% respectively, accounting for 80.12% of the total number of microseismic events within the statistical range, which is greater than 80%. Among them, the microseismic events in the 305 working face were mainly concentrated in the range of 100m ahead of the working face recovery tunnel; the energy events in the goaf of the 203 working face, the goaf of the 307 working face, the goaf of the 409 working face, the goaf of the 308 working face, and the goaf of the 306 working face were less frequent, ranging from 1 to 12 times, especially the microseismic events in the west wing of the 305 working face were mainly concentrated between the transport tunnel of the 307 working face and the transport tunnel of the 305 working face. There is basically no energy in the coal pillar area of ​​the west wing of the 305 working face, that is, between the transport tunnel of the 307 working face and the return air tunnel of the 409 working face. 4 The microseismic events that occurred in the 305 working face were mainly distributed in the 305 goaf, the protective coal pillar between the working face stop mining line and the main roadway, which was mainly affected by F 13 Normal fault influence. There is no large-scale serious damage to the coal and rock mass due to stress concentration on the west and north wings of the 305 working face, energy E≥10 4 The microseismic events of J account for less than 5%, indicating that the west and north wings of the 305 working face can bear the stress disturbance caused by the mining of the 305 working face, that is, the west and north wings of the 305 working face should be solid coal areas, not goaf areas.

[0082] If the longwall coal mining face is equipped with a stress gauge, the support stress analysis method is selected to perform a coal pillar size effect analysis on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is: calculate the width of the lateral coal body plastic zone of the longwall coal mining face based on the limit equilibrium theory. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the sum of the widths of the two plastic zones, then this side is a solid coal area, otherwise this side is a goaf.

[0083] The width of the lateral coal body plastic zone of the longwall coal mining working face is expressed as:

[0084]

[0085] Where x0 represents the width of the lateral plastic zone of the coal body in the longwall mining face; M represents the thickness of the coal seam; λ represents the lateral pressure coefficient; represents the internal friction angle of the coal body; K represents the stress concentration coefficient; γHcosα represents the component of the original rock stress perpendicular to the coal seam when the inclination factor is considered; γH represents the original rock stress; γ represents the average bulk density of the overlying rock strata; H represents the burial depth of the coal seam; α represents the inclination of the coal seam; τ represents the cohesion of the coal body; and N represents the supporting capacity of the coal wall.

[0086] In this embodiment, the lateral plastic zone of the coal body of the 305 working face is calculated according to the limit equilibrium theory, that is, the width of the limit equilibrium zone is 52.3m. Since the width of the coal body on the west wing of the 305 working face is 208m and much larger than the sum of the widths of the two plastic zones, the coal pillar on the west wing of the 305 working face can withstand the lateral support pressure brought by the 305 working face before and after mining and maintain a balanced state, effectively reducing the stress concentration on this side of the 305 working face, and helping to bear the influence of the overburden stratum pressure before the mining of the working face and the increase in the support pressure brought by the mining of the coal mining working face, that is, the coal pillar on the west wing of the 305 working face should be regional solid coal rather than a narrow coal pillar, and this side of the working face is not a goaf.

[0087] If there is a mining face with similar mining conditions to the longwall coal mining face, the engineering analogy method is selected to analyze the coal pillar size effect of the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is: take the mining face with similar mining conditions to the longwall coal mining face as the analogy face, obtain the lateral support pressure or advance support pressure range of the analogy face, and determine the lateral support pressure or advance support pressure range of the longwall coal mining face based on the lateral support pressure or advance support pressure range of the analogy face. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf.

[0088] The similar mining conditions refer to: mining the same coal seam, having the same coal seam thickness and coal seam inclination, and having the same coal mining system and recovery process.

[0089] In this embodiment, if there is a longwall coal mining face in a mining area that mines the same coal seam, has the same coal seam thickness and coal seam inclination, and has the same coal mining system and recovery process, then the lateral support pressure range of the working face is also basically the same.

[0090] In this embodiment, the 513 working face and the 305 working face are both located in the south wing of the downhill area and have similar mining conditions, so the 513 working face and the 305 working face can be compared in engineering. The influence range of the advanced support pressure of the 513 working face is about 120m. Since the average burial depth of the 305 working face is about 250m less than that of the 513 working face, the advanced support pressure range of the 305 working face should be smaller, which should be less than 120m, and significantly less than the minimum width of the coal pillar of the north wing of the 305 working face of 278m. Therefore, the coal in the north wing of the 305 working face can fully withstand the stress increase caused by the mining of the 305 working face, and the north wing of the working face is not a goaf.

[0091] If the longwall coal mining face is not suitable for microseismic analysis, support stress analysis and engineering analogy, physical simulation or numerical simulation is selected to analyze the coal pillar size effect on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area.

[0092] The physical simulation method is as follows: for a longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, a model of the longwall coal mining face is constructed according to the coal seam occurrence conditions of the longwall coal mining face, and a physical similarity simulation test is performed on the model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf.

[0093] In this embodiment, the similarity simulation experiment is a laboratory research method based on similarity theory and dimensional analysis. It is widely used in water conservancy mining projects and is an important means to study the movement and stress characteristics of overburden in mining projects. It can analyze the change laws of surrounding rock stress, rock deformation and movement in the mining area. Similarity simulation mainly includes geometric similarity, time similarity, motion similarity and dynamic similarity. According to the coal seam occurrence conditions of the 305 working face, the similarity simulation ratio of the model is set to 1:50; the experiment is carried out on a plane stress model frame, the model size is 2.15m×0.12m×1.12m, the upper boundary is a free boundary, the original rock stress of the overburden is 34MPa, and the effect of the overburden is achieved by external force compensation method. The geometric dimensions of the direct top module refer to the classification results of the roof in my country and are made according to the model proportion. The geometric dimensions of the basic top module are pressed according to a cycle step and made according to the model proportion. The compressive strength of the rock is the main similarity criterion in the entire production process to meet the strength similarity. The physical simulation results show that the range of advanced support pressure is 136m, and the range of lateral support pressure is 102m. The width of the coal body on the west wing of the 305 working face is 208m, which is greater than the range of lateral support pressure of 102m; the minimum width of the coal pillar on the north wing of the 305 working face is 278m, which is greater than the range of advanced support pressure of 136m. Therefore, the coal on the west and north wings of the 305 working face can fully withstand the stress increase caused by the mining of the 305 working face, and the west and north wings of the working face are not goafs.

[0094] The numerical simulation method is as follows: for a longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, a simulation model of the longwall coal mining face is constructed using numerical simulation software, and a numerical simulation test is performed on the simulation model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf.

[0095] In this embodiment, the numerical simulation test is similar to the physical simulation test, one is achieved through real experiments, and the other is achieved through simulation software. 3D To analyze the distribution characteristics and laws of the support pressure of the coal pillar in the roadway caused by the breakage of the roof of the 305 working face, the coal seam in the simulated working face has an inclination of 19° and a thickness of 10m. The working face has a dip length of 275m, a strike length of 285m, and a remaining minable strike length of 200m. In order to offset the boundary effect, the models on both sides of the working face extend outward by 300, and the model is divided into units of 5m×5m in the x and y directions. The model size is 875m×885m×300m. Using displacement boundary constraints, the velocity in the x direction of the left and right boundaries of the model is zero, the velocity in the y direction of the front and rear boundaries is zero, and the velocity in the x, y, and z directions of the bottom boundary is zero; the upper boundary is a free boundary, and the original rock stress of the overlying stratum is 34MPa. The numerical simulation results show that the range of the advance support pressure is 128m and the range of the lateral support pressure is 96m. The coal body width of the west wing of the 305 working face is 208m, which is greater than the lateral support pressure range of 96m; the minimum width of the coal pillar of the north wing of the 305 working face is 278m, which is greater than the advanced support pressure range of 128m. Therefore, the coal in the west and north wings of the 305 working face can fully withstand the stress increase caused by the mining of the 305 working face, and the west and north wings of the working face are not considered as goaf areas.

[0096] Through the above analysis, the working face, regional structure and working face coal pillar are judged, the situations of irregular working face, boundary fault and irregular coal pillar are equivalently transformed, and the atypical working face layout is transformed into an equivalent typical working face layout.

[0097] In this embodiment, if Figure 3 As shown, the west wing of the 305 working face is equivalent to a solid coal area, not a goaf area, the north wing is equivalent to a solid coal area, not a goaf area, and the east wing of the 305 working face is the 203 goaf area.

[0098] Step S5: Based on the longwall coal mining working face with a typical working face arrangement and the equivalent typical working face of the longwall coal mining working face with an atypical working face arrangement, the island attribute of the longwall coal mining working face is determined to obtain the island attribute determination result of the longwall coal mining working face.

[0099] The method for determining the island attribute of the working face is as follows: taking the longwall coal mining working face of the typical working face arrangement and the equivalent typical working face of the longwall coal mining working face of the atypical working face arrangement as the working face to be determined, and determining whether the working face to be determined meets the typical situation of the island working face, if so, the working face to be determined is an island working face; if not, the working face to be determined is a non-island working face;

[0100] Typical situations of the isolated island working face include: two-sided mining, three-sided mining and four-sided mining.

[0101] The two-sided goaf is a longwall coal mining working face in which the working face belt transport tunnel and the working face return air tunnel are both goaf areas outside, and the rear of the cutting eye and the outside of the working face stop line are both solid coal areas of the longwall coal mining working face.

[0102] The three-sided goaf are the longwall coal mining working face, and the working face belt transport tunnel and the working face return air tunnel are all goaf areas outside, and there is a longwall coal mining working face behind the cutting eye and outside the working face stop mining line with one side being a solid coal area and the other side being a goaf area.

[0103] The four-sided goaf refers to the longwall coal mining working face where the outside of the working face belt transport tunnel, the outside of the working face return air tunnel, the rear of the cutting eye and the outside of the working face stop mining line are all goaf areas.

[0104] In this implementation, according to the interpretation of Article 32 of the Interpretation of the Detailed Rules for Preventing and Controlling Rock Burst in Coal Mines (Beijing: Coal Industry Press, 2018) and the interpretation of Article 11, Paragraph 4 of the Interpretation of the Standards for Determining Major Accident Hazards in Coal Mines (Coal Mine Safety Supervision Department of the State Administration of Mine Safety, 2021-07-12), if the distribution of the selected working face and its surrounding coal pillars and goaf areas can be accurately classified as any of the typical island working faces of "two-sided goaf", "three-sided goaf" and "four-sided goaf", then the selected working face is an island working face, otherwise the selected working face is a non-island working face. Compared with "two-sided goaf", "three-sided goaf" and "four-sided goaf", the 305 working face does not belong to any of them, that is, the 305 working face is a non-island working face.

[0105] The core content of the present invention is to transform atypical situations into typical situations through computational analysis, so as to make judgments using existing methods.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for determining the island attribute of a longwall coal mining face, characterized in that: The method comprises the following steps: Step S1: obtaining a mining engineering plan of a longwall coal mining face, and selecting a longwall coal mining face to be analyzed; Step S2: collecting mining information of the longwall coal mining face to be analyzed, and drawing a working face layout diagram of the longwall coal mining face according to the mining information and the mining engineering plan of the longwall coal mining face; Step S3: judging, according to the working face layout diagram of the longwall coal mining working face, whether the working face layout of the longwall coal mining working face is a typical working face layout or an atypical working face layout; Step S4: typify the longwall coal mining working face with the atypical working face arrangement to obtain an equivalent typical working face arrangement of the longwall coal mining working face; Step S5: Based on the longwall coal mining working face with a typical working face arrangement and the equivalent typical working face of the longwall coal mining working face with an atypical working face arrangement, the island attribute of the longwall coal mining working face is determined to obtain the island attribute determination result of the longwall coal mining working face.

2. A method for determining the island attribute of a longwall coal mining face according to claim 1, characterized in that: The four boundaries of the longwall coal mining working face are: the working face belt transport tunnel, the working face return air tunnel, the longwall coal mining working face cutting eye and the working face stop mining line.

3. The method for determining the island attribute of a longwall coal mining face according to claim 2, characterized in that: The mining information in step S2 includes: the structure, shape, range and size parameters of the longwall coal mining working face, and the position and range of the coal pillars adjacent to the longwall coal mining working face.

4. A method for determining the island attribute of a longwall coal mining face according to claim 3, characterized in that: The method for determining the working face arrangement in step 3 is as follows: for any longwall coal mining working face, judging whether the longwall coal mining working face satisfies the following three conditions at the same time according to the mining information of the longwall coal mining working face, including: Condition 1: The longwall coal mining face is a rectangular face; Condition 2: There is no boundary fault between the longwall coal mining face and other solid coal areas other than the longwall coal mining face; Condition 3: There are clearly identifiable goaf areas and solid coal areas on the four boundary sides of the longwall mining face; If it is satisfied, the longwall coal mining working face is a typical working face; if it is not satisfied, the longwall coal mining working face is an atypical working face.

5. A method for determining the island attribute of a longwall coal mining face according to claim 4, characterized in that: The clearly identifiable goaf and solid coal area refer to: for the coal pillar adjacent to any boundary side of the longwall coal mining working face, if the coal pillar is a narrow long coal pillar with a width of 0m-30m, then there is a clearly identifiable goaf area on this side of the longwall coal mining working face; if the minimum width of the coal pillar is greater than or equal to the dip length B of the longwall coal mining working face, then there is a clearly identifiable solid coal area on this side of the longwall coal mining working face.

6. A method for determining the island attribute of a longwall coal mining face according to claim 5, characterized in that: The typical process described in step 4 includes: Step A1: determine whether the longwall coal mining working face is a special-shaped working face. If not, do not perform equivalence on the longwall coal mining working face; if yes, perform equivalence on the longwall coal mining working face as a rectangular working face with a goaf behind the opening of the longwall coal mining working face; The special-shaped working surface refers to a working surface with a triangular shape or a working surface with a trapezoidal shape; Step A2: determining whether the longwall coal mining face contains a boundary fault, if not, not performing equivalence on the longwall coal mining face; if yes, performing equivalence on the side of the longwall coal mining face where the boundary fault is located as a goaf; The situations where the longwall coal mining face contains boundary faults include: a boundary side of the longwall coal mining face is a boundary fault, a boundary fault exists at the opening of the longwall coal mining face, or a boundary fault exists on one side of the stop line of the longwall coal mining face; Step A3: Determine whether there is a clearly identifiable goaf area or solid coal area in the longwall coal mining working face. If so, do not perform equivalence on the longwall coal mining working face. Otherwise, perform a working face coal pillar size effect analysis on the coal pillar on one side of the longwall coal mining working face where there is no clearly identifiable goaf area or solid coal area, and determine whether that side of the longwall coal mining working face is a solid coal area or a goaf area based on the analysis results.

7. A method for determining the island attribute of a longwall coal mining face according to claim 6, characterized in that: The method for analyzing the size effect of coal pillars in the working face includes: microseismic analysis, support stress analysis, engineering analogy, physical simulation or numerical simulation; For a longwall coal mining face without a clearly identifiable goaf or solid coal area, a method is selected from the above methods according to the mine conditions of the mine where the longwall coal mining face is located to perform a coal pillar size effect analysis on the side of the longwall coal mining face without a clearly identifiable goaf or solid coal area. The specific process is as follows: If a microseismic monitoring system is deployed in the mine where the longwall coal mining face is located, the microseismic analysis method is selected to analyze the size effect of the coal pillar on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: for any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, the energy E generated by the coal pillar on this side within a certain period of time and the frequency and distribution of microseismic events on this side are counted. If the energy E on this side is ≥10 4 If the frequency of microseismic events on J accounts for less than 5% of the frequency of microseismic events occurring within the longwall coal mining face and within the coal pillars or goafs adjacent to the longwall coal mining face, then this side is a solid coal area; otherwise, this side is a goaf; If the longwall coal mining face is equipped with a stress gauge, the support stress analysis method is selected to analyze the size effect of the coal pillar on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: the width of the lateral coal body plastic zone of the longwall coal mining face is calculated according to the limit equilibrium theory. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the sum of the widths of the two plastic zones, then this side is a solid coal area, otherwise this side is a goaf; If there is a mining face with similar mining conditions to the longwall coal mining face, the engineering analogy method is selected to analyze the coal pillar size effect of the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The analysis process is as follows: take the mining face with similar mining conditions to the longwall coal mining face as the analogy face, obtain the lateral support pressure or advance support pressure range of the analogy face, and determine the lateral support pressure or advance support pressure range of the longwall coal mining face according to the lateral support pressure or advance support pressure range of the analogy face. For any side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf; Similar mining conditions refer to: mining the same coal seam, the same coal seam thickness and coal seam inclination, and the same coal mining system and recovery process; If the longwall coal mining face is not suitable for microseismic analysis, support stress analysis and engineering analogy, physical simulation or numerical simulation is used to analyze the coal pillar size effect on the side of the longwall coal mining face where there is no clearly identifiable goaf or solid coal area. The physical simulation method is as follows: for a longwall coal mining face without a clearly identifiable goaf or solid coal area, a model of the longwall coal mining face is constructed according to the coal seam occurrence conditions of the longwall coal mining face, and a physical similarity simulation test is performed on the model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face without a clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on the side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then the side is a solid coal area, otherwise the side is a goaf; The numerical simulation method is as follows: for a longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, a simulation model of the longwall coal mining face is constructed using numerical simulation software, and a numerical simulation test is performed on the simulation model to obtain the lateral support pressure or advance support pressure range of the longwall coal mining face. For any side of the longwall coal mining face in which there is no clearly identifiable goaf or solid coal area, if the minimum width of the coal pillar on this side is greater than the lateral support pressure or advance support pressure range of the longwall coal mining face, then this side is a solid coal area, otherwise this side is a goaf.

8. A method for determining the island attribute of a longwall coal mining face according to claim 7, characterized in that: The width of the lateral coal body plastic zone of the longwall coal mining working face is expressed as: Where x0 represents the width of the lateral plastic zone of the coal body in the longwall mining face; M represents the thickness of the coal seam; λ represents the lateral pressure coefficient; represents the internal friction angle of the coal body; K represents the stress concentration coefficient; γHcosα represents the component of the original rock stress perpendicular to the coal seam when the inclination factor is considered; γH represents the original rock stress; γ represents the average bulk density of the overlying rock strata; H represents the burial depth of the coal seam; α represents the inclination of the coal seam; τ represents the cohesion of the coal body; and N represents the supporting capacity of the coal wall.

9. A method for determining the island attribute of a longwall coal mining face according to claim 8, characterized in that: The method for determining the island attribute of the working face is as follows: taking the longwall coal mining working face of the typical working face arrangement and the equivalent typical working face of the longwall coal mining working face of the atypical working face arrangement as the working face to be determined, and determining whether the working face to be determined meets the typical situation of the island working face, if so, the working face to be determined is an island working face; if not, the working face to be determined is a non-island working face; Typical situations of the isolated island working face include: two-sided mining, three-sided mining and four-sided mining; The two-sided goaf is a longwall coal mining face in which the outer sides of the belt transport lane and the return air lane of the working face are both goaf areas, and the rear of the cut eye and the outer side of the working face stop line are both solid coal areas; The three-sided goaf is a longwall coal mining face, the working face belt transport lane and the working face return air lane outside are all goaf areas, and there is a longwall coal mining face behind the cut eye and outside the working face stop line with one side being a solid coal area and the other side being a goaf area; The four-sided goaf refers to the longwall coal mining working face where the outside of the working face belt transport tunnel, the outside of the working face return air tunnel, the rear of the cutting eye and the outside of the working face stop mining line are all goaf areas.

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