A method for excavating and withdrawing roadways and equipment before stopping mining lines.

Abstract

This invention discloses a method for excavating and withdrawing roadways and equipment before a mining cessation line, comprising the following steps: (1) determining the range of the stress reduction zone caused by advanced mining; (2) supporting the area affected by advanced mining; (3) excavating roadways, excavating transfer chambers, and chamfering corners; (4) supporting the withdrawal space; and (5) withdrawing equipment. This invention provides a method for excavating and withdrawing a roadway on-site before a mining cessation line based on the advanced support stress curve, achieving a synergistic effect between the roadway excavation and support shielding.

Description

Technical Field

[0001] This invention relates to the field of coal mining, and in particular to a method for excavating and withdrawing roadways and equipment before a mining line is shut down. Background Technology

[0002] After the longwall mining face is completed, large equipment such as hydraulic supports needs to be moved to the next working face; this process is commonly known as "working face relocation." Currently, there are generally two methods for equipment relocation: excavating relocation channels in place and pre-excavating relocation channels. The former has an unsafe working space, is time-consuming and labor-intensive, and the average relocation time is 1 to 2 months. The pre-excavated relocation channel technology involves pre-excavating a relocation channel parallel to the coal mining face near the final mining line. Once the coal mining face and the pre-excavated relocation channel are connected, this pre-excavated channel is used as the channel for removing equipment. Pre-excavated relocation channels offer a safe working space, significantly reduce the difficulty of equipment relocation, and can be carried out simultaneously with coal mining on the working face, saving a lot of time in relocating equipment. However, since the pre-excavated relocation channel is completed before the working face is mined, the dynamic support pressure from the advanced working face mining can easily lead to accidents such as crushing the coal pillars in the final mining section and killing the hydraulic supports. Therefore, the support effect of the pre-excavated relocation channel directly affects the handover of the working face and mine production. Summary of the Invention

[0003] This invention provides a method for excavating and withdrawing a tunnel on-site before the mining line is stopped, based on the pre-support stress curve, thereby achieving a coordinated effect between the tunnel excavation and support shielding.

[0004] A method for excavating and retracting roadways and equipment before a mining line is shut down includes the following steps:

[0005] (A) Determine the extent of the stress reduction zone caused by advance mining;

[0006] (B) Support for the area affected by advanced mining;

[0007] (C) Excavate tunnels, excavate transfer chambers, and chamfer corners;

[0008] (D) Retreat space support;

[0009] (E) Retraction equipment.

[0010] The method for excavating and withdrawing roadways and equipment before the stop mining line as described in this invention includes the following steps in step (A): combining the on-site mining process and numerical simulation calculations to analyze the characteristics of the impact of advance mining on the fully mechanized longwall face, calculating the stress concentration coefficient and mining damage depth of the impact of advance mining on the fully mechanized longwall face, and then determining the range of the mining stress reduction zone.

[0011] The method for excavating and withdrawing roadways and equipment before the stop-mining line as described in this invention, wherein the calculation process in step (A) is as follows:

[0012] ① Determine the length of the basic roof cantilever structure based on the pressure manifestation law of the working face, and take the periodic pressure step distance L. b Based on the principle of force equivalence, the equilibrium equation for the transmission of mining power in front of the coal face in a fully mechanized longwall mining face is established through integration:

[0013]

[0014] In the formula: L b The period is used to adjust the step size, m; e is the natural constant, the base of the natural logarithm function, with a value of 2.718; P z σ is the original rock stress, MPa; β = 2f / m; m is the thickness of the lateral edge coal and rock mass, m; f is the frictional resistance coefficient of the lateral coal and rock mass boundary slippage; σ c Uniaxial compressive strength, MPa C represents cohesion, measured in MPa. The internal friction angle is °; P j The horizontal resistance of the coal face is measured in MPa; y p The depth of coal face damage caused by advanced mining, in meters;

[0015] ② Perform univariate numerical calculations on step ① to obtain the depth y of the coal face under pre-mining damage in the fully mechanized longwall face. p ;

[0016] ③ Calculate the stress concentration factor caused by mining from step ②:

[0017] ④ Calculate the vertical stress distribution of the coal face under advance mining from step ②:

[0018]

[0019] In the formula: The vertical stress in MPa represents the mining-induced stress in the advanced coal and rock failure zone and elastic zone in front of the coal face.

[0020] ⑤ After calculating the advanced support stress, based on the calculated stress reduction zone distance y p Determine the width y of the excavation and withdrawal tunnel. c :

[0021] Let 0≤y≤y p time The calculated y is y c .

[0022] The method for excavating and withdrawing roadways and equipment before the stop mining line as described in this invention includes the following specific support measures in step (B) for the pre-mining impact zone: end support is provided at both ends of the working face using a passive support method of 3 single-column + π-beam; reinforced support is provided in the roadway within the original rock stress zone using a passive support method of 2 single-column + π-beam; and active reinforced support is provided in the roadway within the stress increase zone using a 3-anchor cable + steel beam method.

[0023] The method for excavating and withdrawing roadways and equipment before the stop mining line as described in this invention, wherein the distance between two adjacent supports is 1.0m.

[0024] The method for excavating and withdrawing roadways and equipment before the cessation of mining as described in this invention includes the following specific support measures for the withdrawal space in step (D): the withdrawal passage, transfer chamber, and radius corner are supported by two types of active support: 3 anchor cables + steel ladder beams and passive support: 2 single columns + π-shaped beams. The two types of support are set at intervals.

[0025] The method for excavating and withdrawing roadways and equipment before the stop-mining line as described in this invention, wherein the distance between two adjacent supports is 0.7m.

[0026] The method for excavating and withdrawing roadways and equipment before the shutdown of mining lines as described in this invention, wherein the "cornering" refers to applying a radius of y to the coal face at the auxiliary transport end of the working face. c The corners are rounded off.

[0027] The method for excavating and withdrawing roadways and equipment before the shutdown line as described in this invention, wherein step (E) of withdrawing the equipment specifically includes the following steps:

[0028] (a) Retraction of the front scraper conveyor and the coal mining machine;

[0029] (b) Number the hydraulic supports using the following method: starting from the main haulage roadway and ending at the auxiliary haulage roadway, number the hydraulic supports on the working face sequentially, starting from 1. # Up to 128 # ;

[0030] (c) 1 # 2 # and 3 # Remove the rear scraper conveyor and promptly install interlocking timber stacks at the original hydraulic support location;

[0031] (d) First, put 5 # The hydraulic supports were removed and transported away using a forklift. Interlocking timber stacks were promptly erected at the original location of the hydraulic supports, and then 4... # Half of the support frame was extended to serve as a cover support, and a stack of timbers was erected behind the cover support; 7% was extended... # The hydraulic supports were removed and transported away, and interlocking timber stacks were promptly erected in their original locations. Then, 6...# The hydraulic support was partially extended to serve as a protective support, and a timber stack was erected behind the protective support; 90% of the hydraulic support was extended... # The hydraulic supports were removed and transported away, and interlocking timber stacks were promptly erected in their original locations. Then, 8... # The hydraulic supports are withdrawn halfway to serve as cover supports, and timber stacks are erected behind the cover supports; the withdrawal method for even-numbered hydraulic supports and odd-numbered hydraulic supports is repeated, and so on up to 125. # ;

[0032] (e) 126 # 127 # 128 # The hydraulic supports were pulled out halfway at a time, and then raised up for cover, before being withdrawn in four stages. # 6 # 8 # ...124 # The remaining half of the hydraulic support, finally 126 # 127 # 128 # The hydraulic supports were withdrawn in sequence, completing the retreat of the working face.

[0033] The method for excavating and retracting roadways and equipment before stopping mining in this invention differs from existing technologies in that:

[0034] The method for excavating and retracting roadways and equipment before stopping mining lines, as described in this invention, has the following beneficial effects:

[0035] 1. Radius shaving: The radius shaving area is a necessary passage for material handling and a transportation hub. Using a radius shaving method can increase space and speed up the retraction of equipment. Secondly, the coal seam at the radius shaving area is already a broken and soft seam, prone to spalling, posing a risk of injury and hindering coal wall support. Thirdly, using a radius of y... c The radius of the bevel is beneficial to strengthening the coal wall support and safety, and does not affect the safety of the roadway support due to the expansion of the excavation space.

[0036] 2. The pre-excavation and withdrawal roadway before the stop-mining line overcomes the problem of traditional pre-excavated withdrawal channels being completed ahead of the working face mining. Under the influence of the dynamic support pressure from the advanced mining face, accidents such as crushing of the final coal pillar and killing of hydraulic supports are easily caused. This invention achieves safe, pressure-free, rapid, and low-cost withdrawal of the final mining equipment. The withdrawal method of the final mining equipment in this invention not only avoids the strong influence of the advanced mining face, but also has a fast withdrawal speed and low cost, fundamentally solving the drawbacks of traditional support withdrawal.

[0037] 3. The retreat roadway begins to be excavated one width before the stop-mining line. The excavated material is coal, which does not affect the recovery rate. The general coal roadway excavation speed is 450m / month. However, when excavating in front of the working face, the support space, ventilation and other conditions are greatly improved, and the excavation speed can reach 800m / month. The excavation speed of the retreat roadway for a 200mm long working face is about 7 days, while the coal mining machine takes about 1 day. However, considering the pre-excavation of the retreat channel hundreds of meters ahead, the resulting personnel diversion, long-term ventilation, support and maintenance workload, and most importantly, the slow retreat speed caused by the impact of the dynamic support pressure ahead, which may lead to the collapse of the coal pillar in the final mining section and the crushing of the hydraulic support, the invention does not show a disadvantage in retreat time and is superior in safety and efficiency.

[0038] 4. Width of the retreat roadway: The distance calculation of the retreat roadway is based on scientific models and theories. Furthermore, the retreat roadway is excavated starting from the width of the retreat roadway one step before the stop-mining line. Many of the data used can be measured on-site, further increasing reliability and safety. Pre-excavated retreat channels cannot achieve on-site data measurement, thus compromising accuracy.

[0039] The method for excavating and withdrawing roadways and equipment before the stop-mining line according to the present invention will be further described below with reference to the accompanying drawings. Attached Figure Description

[0040] Figure 1 This is a curve showing the vertical stress distribution of the coal face during advance mining in the fully mechanized mining face of this invention.

[0041] Figure 2 This is a schematic diagram of the support and withdrawal equipment method in this invention;

[0042] Figure 3 This is a curve showing the vertical stress distribution of the coal face during advance mining in Embodiment 2 of the present invention. Detailed Implementation

[0043] Example 1

[0044] A method for excavating and retracting roadways and equipment before a mining line is shut down includes the following steps:

[0045] (A) Determine the range of stress reduction zone for advance mining: Combine the on-site mining process and numerical simulation calculation to analyze the impact characteristics of advance mining in fully mechanized longwall mining face, calculate the stress concentration coefficient and mining failure depth of advance mining impact in fully mechanized longwall mining face, and then determine the range of stress reduction zone for mining.

[0046] The calculation process is as follows:

[0047] ① Determine the length of the basic roof cantilever structure based on the pressure manifestation law of the working face, and take the periodic pressure step distance L. bBased on the principle of force equivalence, the equilibrium equation for the transmission of mining power in front of the coal face in a fully mechanized longwall mining face is established through integration:

[0048]

[0049] In the formula: L b The period is used to adjust the step size, m; e is the natural constant, the base of the natural logarithm function, with a value of 2.718; P z σ is the original rock stress, MPa; β = 2fm; m is the thickness of the lateral edge coal and rock mass, m; f is the frictional resistance coefficient of the lateral coal and rock mass boundary slippage; σ c Uniaxial compressive strength, MPa C represents cohesion, measured in MPa. The internal friction angle is °; P j The horizontal resistance of the coal face is measured in MPa; y p The depth of coal face damage caused by advanced mining, in meters;

[0050] ② Perform univariate numerical calculations on step ① to obtain the depth y of the coal face under pre-mining damage in the fully mechanized longwall face. p ;

[0051] ③ Calculate the stress concentration factor caused by mining from step ②:

[0052] ④ Calculate the vertical stress distribution of the coal face under advance mining from step ②:

[0053]

[0054] In the formula: The vertical stress in MPa represents the mining-induced stress in the advanced coal and rock failure zone and elastic zone in front of the coal face.

[0055] The final vertical stress distribution curve of the coal face under advance mining is as follows: Figure 1 As shown in the figure, the left side of hydraulic support 1 is the goaf, and the right side is coal seam 2. Stress change refers to the change in stress distribution within coal seam 2 after excavation of a certain distance. The original stress distribution characteristics (γH) change to KγH, forming a stress-reduced zone ahead of the coal face. If this channel is excavated hundreds or tens of meters ahead of the face using traditional methods, the point of maximum stress support will inevitably be crushed during the advancement of coal seam 2, causing damage and instability to the pre-excavated roadway. This invention, based on precise calculations, excavates the roadway within the stress-reduced zone, ensuring roadway safety, reliability, and stability. Furthermore, the coal seam 2 within the stress-reduced zone has already undergone plastic deformation, significantly reducing excavation difficulty, lowering costs, and improving excavation efficiency.

[0056] ⑤ After calculating the advanced support stress, based on the calculated stress reduction zone distance y p Determine the width y of the excavation and withdrawal tunnel. c :

[0057] Let 0≤y≤y p time The calculated y is y c .

[0058] Extensive statistical data proves that, under normal circumstances, y p All are greater than 3.5m, and very few have y p For cases less than 3.5m, therefore if y p A depth of less than 3.5m indicates that this coal seam is extremely difficult to control due to the surrounding rock of the roadway. Any retreat method would be very challenging, therefore y is not considered here. p For cases less than 3.5m.

[0059] (B) Support for the affected area of ​​advanced mining, such as Figure 2 As shown:

[0060] End support is provided at both ends of the working face. The support method is passive support of 3 single columns + π-shaped beams.

[0061] Strengthen the support in the roadway within the original rock stress zone. The support method is 2 single-column + π-shaped beam passive support.

[0062] The support method for roadways in areas with increased stress is 3 anchor cables + steel beam active reinforcement support 6.

[0063] The distance between two adjacent supports is 1.0m.

[0064] (C) Excavate the tunnel, excavate the transfer chamber and chamfer the corner 4; Figure 2 The right side shows the stress curve. In the stress reduction zone, the retreat roadway is excavated, and the corner 4 is used to reinforce the coal face at the auxiliary transport end with a radius of y. c 4. The rounding.

[0065] The area at radius 4 is a crucial passageway for material handling and a key transportation hub. Using radius 4 increases space and accelerates the speed and efficiency of equipment retraction. Secondly, coal seam 2 at the radius 4 is already a broken and soft seam, prone to spalling, posing a risk of injury and hindering coal wall support. Thirdly, using a radius of y... c The radius of the chamfer is 4, which helps to strengthen the coal wall support and safety, and does not affect the safety of the roadway support due to the expansion of the excavation space.

[0066] (D) Retreat Space Support: The retreat passage, transfer chamber and radius chamfer 4 adopt two types of active support: 3 anchor cables + steel ladder beams and passive support: 2 single columns + π-shaped beams. The two types of support are set at intervals, and the distance between two adjacent supports is 0.7m.

[0067] (E) Retracting the equipment, specifically including the following steps:

[0068] (a) Retraction of the front scraper conveyor 11 and the coal mining machine 10;

[0069] (b) Number the hydraulic supports 1 sequentially, starting from the main haulage roadway and ending at the auxiliary haulage roadway. # Up to 128 # ;

[0070] (c) 1 # 2 # and 3 # Remove the rear scraper conveyor 12 and promptly install a chain-linked timber stack at the original hydraulic support 1 position;

[0071] (d) First, put 5 # Hydraulic support 1 was removed and transported away using a forklift. A chain of interlocking timbers was promptly erected at the original location of hydraulic support 1. Then, 4... # Hydraulic support 1 is partially extended to serve as a protective support, and a timber stack is erected behind the protective support; 7 is extended... # Hydraulic support 1 was removed and transported away, and a chain-linked timber stack was promptly erected at the original location of hydraulic support 1. Then, 6... # Hydraulic support 1 is partially extended to serve as a protective support, and a timber stack is erected behind the protective support; 9 is extended... # Hydraulic support 1 was removed and transported away, and a chain-linked timber stack was promptly erected at the original location of hydraulic support 1. Then, 8... # Hydraulic support 1 is withdrawn halfway to serve as a cover support, and a timber stack is erected behind the cover support; the withdrawal method for even-numbered hydraulic supports 1 and odd-numbered hydraulic supports 1 is repeated, and so on up to 125. # ;

[0072] (e) 126 # 127 # 128 # Hydraulic support 1 is pulled out halfway in sequence, and then raised to provide cover, before 4 are withdrawn. # 6 # 8 # ...124 # The remaining half of hydraulic support 1, finally 126 # 127 # 128 #Hydraulic support 1 was withdrawn in sequence, completing the withdrawal of the working face.

[0073] Example 2

[0074] A method for excavating and retracting roadways and equipment before a mining line is shut down includes the following steps:

[0075] (A) Determine the range of stress reduction zone for advance mining: Combine the on-site mining process and numerical simulation calculation to analyze the impact characteristics of advance mining in fully mechanized longwall mining face, calculate the stress concentration coefficient and mining failure depth of advance mining impact in fully mechanized longwall mining face, and then determine the range of stress reduction zone for mining.

[0076] The calculation process is as follows:

[0077] ① Determine the length of the basic roof cantilever structure based on the pressure manifestation law of the working face, and take the periodic pressure step distance L. b Based on the principle of force equivalence, the equilibrium equation for the transmission of mining power in front of the coal face in a fully mechanized longwall mining face is established through integration:

[0078]

[0079] Taking a working face in a mine in Inner Mongolia as an example, in the formula: L b The period is used to adjust the step size, which is taken as 15m; e is the natural constant, the base of the natural logarithm function, with a value of 2.718; P z The original rock stress is taken as 10 MPa; β = 2fm; m is the thickness of the lateral edge coal and rock mass, taken as 5 m; f is the frictional resistance coefficient of the lateral coal and rock mass boundary slippage, taken as 0.2; β is calculated to be 0.08, σ c Uniaxial compressive strength, MPa The calculated uniaxial compressive strength is 4.08 MPa, where C is the cohesion, taken as 1.3 MPa. The internal friction angle is set to 25°. The calculated value is 2.46; P j The horizontal resistance of the coal face is taken as 0 MPa; y p The depth of coal face damage caused by advanced mining, in meters;

[0080] ② Perform univariate numerical calculations on step ① to obtain the depth y of the coal face under pre-mining damage in the fully mechanized longwall face. p The calculated result is 9.17m.

[0081] ③ Calculate the stress concentration factor caused by mining from step ②: The calculated result is 2.48.

[0082] ④ Calculate the vertical stress distribution of the coal face under advance mining from step ②:

[0083] The final vertical stress distribution curve of the coal face under advance mining is as follows: Figure 3 As shown,

[0084] ⑤ After calculating the advanced support stress, based on the calculated stress reduction zone distance y p Determine the width y of the excavation and withdrawal tunnel. c :

[0085] Let 0≤y≤y p time The calculated y is y c Find y c =4.58m, that is, the width of the retreat tunnel is 4.58m.

[0086] (B) Support for the affected area of ​​advanced mining, such as Figure 2 As shown:

[0087] End support is provided at both ends of the working face. The support method is passive support of 3 single columns + π-shaped beams.

[0088] Strengthen the support in the roadway within the original rock stress zone. The support method is 2 single-column + π-shaped beam passive support.

[0089] The support method for roadways in areas with increased stress is 3 anchor cables + steel beam active reinforcement support 6.

[0090] The distance between two adjacent supports is 1.0m.

[0091] (C) Excavate the tunnel, excavate the transfer chamber and chamfer the corner 4; Figure 2 The right side shows the stress curve. In the stress reduction zone, the retreat roadway is excavated, and the corner 4 is used to reinforce the coal face at the auxiliary transport end with a radius of y. c 4. The rounding.

[0092] The area at radius 4 is a crucial passageway for material handling and a key transportation hub. Using radius 4 increases space and accelerates the speed and efficiency of equipment retraction. Secondly, coal seam 2 at the radius 4 is already a broken and soft seam, prone to spalling, posing a risk of injury and hindering coal wall support. Thirdly, using a radius of y... c The radius of the chamfer is 4, which helps to strengthen the coal wall support and safety, and does not affect the safety of the roadway support due to the expansion of the excavation space.

[0093] (D) Retreat Space Support: The retreat passage, transfer chamber and radius chamfer 4 adopt two types of active support: 3 anchor cables + steel ladder beams and passive support: 2 single columns + π-shaped beams. The two types of support are set at intervals, and the distance between two adjacent supports is 0.7m.

[0094] (E) Retracting the equipment, specifically including the following steps:

[0095] (a) Retraction of the front scraper conveyor 11 and the coal mining machine 10;

[0096] (b) Number the hydraulic supports 1 sequentially, starting from the main haulage roadway and ending at the auxiliary haulage roadway. # Up to 128 # ;

[0097] (c) 1 # 2 # and 3 # Remove the rear scraper conveyor 12 and promptly install a chain-linked timber stack at the original hydraulic support 1 position;

[0098] (d) First, put 5 # Hydraulic support 1 was removed and transported away using a forklift. A chain of interlocking timbers was promptly erected at the original location of hydraulic support 1. Then, 4... # Hydraulic support 1 is partially extended to serve as a protective support, and a timber stack is erected behind the protective support; 7 is extended... # Hydraulic support 1 was removed and transported away, and a chain-linked timber stack was promptly erected at the original location of hydraulic support 1. Then, 6... # Hydraulic support 1 is partially extended to serve as a protective support, and a timber stack is erected behind the protective support; 9 is extended... # Hydraulic support 1 was removed and transported away, and a chain-linked timber stack was promptly erected at the original location of hydraulic support 1. Then, 8... # Hydraulic support 1 is withdrawn halfway to serve as a cover support, and a timber stack is erected behind the cover support; the withdrawal method for even-numbered hydraulic supports 1 and odd-numbered hydraulic supports 1 is repeated, and so on up to 125. # ;

[0099] (e) 126 # 127 # 128 # Hydraulic support 1 is pulled out halfway in sequence, and then raised to provide cover, before 4 are withdrawn. # 6 # 8 # ...124 # The remaining half of hydraulic support 1, finally 126 # 127 # 128 # Hydraulic support 1 was withdrawn in sequence, completing the withdrawal of the working face.

[0100] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for excavating and withdrawing roadways and equipment before a mining line is shut down, characterized in that: Includes the following steps: (A) Determine the range of stress reduction zone for advance mining: Combine the on-site mining process and numerical simulation calculation to analyze the impact characteristics of advance mining in fully mechanized longwall mining face, calculate the stress concentration factor and mining failure depth of advance mining impact in fully mechanized longwall mining face, and then determine the range of stress reduction zone for mining. The calculation process is as follows: ① Determine the length of the basic roof cantilever structure based on the pressure manifestation law of the working face, and take the periodic pressure step distance L. b Based on the principle of force equivalence, the equilibrium equation for the transmission of mining power in front of the coal face in a fully mechanized longwall mining face is established through integration: ； In the formula: L b The step size is determined by the period, in meters (m). e, the natural constant, is the base of the natural logarithm function, and its value is 2.718; P z The stress is the original rock stress, in MPa. ; m is the thickness of the lateral edge coal and rock mass, in meters; f is the frictional resistance coefficient of the lateral coal and rock mass boundary slippage; Uniaxial compressive strength, MPa C represents cohesion, in MPa. The internal friction angle is °; ;P j The horizontal resistance of the coal face is measured in MPa. y p The depth of coal face damage caused by advanced mining, in meters; ② Perform univariate numerical calculations on step ① to obtain the depth y of the coal face under-mining failure in the fully mechanized longwall face. p ; ③ Calculate the stress concentration factor caused by mining from step ②: ; ④ Calculate the vertical stress distribution of the coal face under advance mining from step ②: ； In the formula: , The vertical stress in MPa represents the mining-induced stress in the advanced coal and rock failure zone and elastic zone in front of the coal face. ⑤ After calculating the advanced support stress, based on the calculated stress reduction zone distance y p Determine the width y of the excavation and withdrawal tunnel. c : make time The calculated y is y c ; (B) Support for the area affected by advanced mining; (C) Excavate the tunnel, excavate the transfer chamber, and chamfer the corners; (D) Retreat space support; (E) Retracting the equipment, specifically including the following steps: (a) Retraction of the front scraper conveyor and the coal mining machine; (b) Number the hydraulic supports using the following method: starting from the main haulage roadway and ending at the auxiliary haulage roadway, number the hydraulic supports on the working face sequentially, starting from 1. # Up to 128 # ; (c) 1 # 2 # and 3 # Remove the rear scraper conveyor and promptly install interlocking timber stacks at the original hydraulic support location; (d) First, put 5 # The hydraulic supports were removed and transported away using a forklift. Interlocking timber stacks were promptly erected at the original location of the hydraulic supports, and then 4... # Half of the support frame was extended to serve as a cover support, and a stack of timbers was erected behind the cover support; 7% was extended... # The hydraulic supports were removed and transported away, and interlocking timber stacks were promptly erected in their original locations. Then, 6... # The hydraulic support was partially extended to serve as a protective support, and a timber stack was erected behind the protective support; 90% of the hydraulic support was extended... # The hydraulic supports were removed and transported away, and interlocking timber stacks were promptly erected in their original locations. Then, 8... # The hydraulic supports are withdrawn halfway to serve as cover supports, and timber stacks are erected behind the cover supports; the withdrawal method for even-numbered hydraulic supports and odd-numbered hydraulic supports is repeated, and so on up to 125. # ; (e) 126 # 127 # 128 # The hydraulic supports were pulled out halfway at a time, and then raised up for cover, before being withdrawn in four stages. # 6 # 8 # ...124 # The remaining half of the hydraulic support was finally 126. # 127 # 128 # The hydraulic supports were withdrawn in sequence, completing the retreat of the working face.

2. The method for excavating and withdrawing roadways and equipment before the mining line is stopped, as described in claim 1, is characterized in that: In step (B), the support for the advanced mining-affected area is as follows: end support is provided at both ends of the working face, and the support method is passive support of 3 single columns + π-shaped beams; reinforced support is provided in the roadway in the original rock stress zone, and the support method is passive support of 2 single columns + π-shaped beams; the support method for the roadway in the stress-increased zone is active reinforced support of 3 anchor cables + steel beams.

3. The method for excavating and withdrawing roadways and equipment before the mining line is stopped, as described in claim 2, is characterized in that: The distance between two adjacent supports is 1.0m.

4. The method for excavating and withdrawing roadways and equipment before the mining line is stopped, as described in claim 1, is characterized in that: The specific support for the retreat space in step (D) is as follows: the retreat passage, transfer chamber and radius corner adopt two types of active support: 3 anchor cables + steel ladder beams and passive support: 2 single columns + π-shaped beams. The two types of support are set at intervals.

5. The method for excavating and withdrawing roadways and equipment before the stop-mining line as described in claim 4, characterized in that: The distance between two adjacent supports is 0.7m.

6. The method for excavating and withdrawing roadways and equipment before the stop-mining line as described in claim 1, characterized in that: The squeegee refers to applying a radius of y to the coal face at the auxiliary transport end of the working face. c The corners are rounded off.

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