Method for leaving roadway in single steeply inclined medium-thick coal seam top coal caving mining

Abstract

This invention discloses a method for retaining roadways in single steeply inclined medium-thick coal seams during top-coal caving mining, relating to the field of roadway retention technology in coal seam mining. The method includes: dividing the coal seam into several segments along its dip direction, with only one roadway in each segment; excavating the roadway horizontally along the thickness of the medium-thick coal seam, resulting in a right-angled trapezoidal cross-section; providing temporary support for the roadway after its formation; continuously excavating the roadway from the haulage uphill direction at the working face towards the return air uphill direction until the roadway connects both the haulage uphill and return air uphill directions; after roadway excavation, supporting it with hydraulic supports and installing a rockfall curtain; arranging grouting pipes within the goaf formed after the roadway's centerline advances, creating a windbreak curtain in the goaf; and suspending windbreaks inside the rockfall curtain to preserve the roadway within the rock strata, forming a return air passage. This method avoids spontaneous combustion of coal in the goaf and reduces the amount of roadway excavation.

Description

Technical Field

[0001] This invention relates to the field of roadway retention technology in coal seam mining, specifically to a method for roadway retention in single steeply inclined medium-thick coal seam top coal caving mining. Background Technology

[0002] Steeply inclined medium-thick coal seams account for a small portion of my country's total coal reserves, and these resources are largely high-quality. However, mining steeply inclined medium-thick coal seams presents significant technical challenges. Because the seam angle is greater than 45°, the layout of the pre-mining roadways and the mining methods differ markedly from those for gently inclined coal seams.

[0003] Currently, the main methods for mining steeply inclined medium-thick coal seams include: reverse bench mining, inclined bench mining, and pseudo-inclined flexible shield support mining. However, certain technical problems still exist.

[0004] Firstly, the existing steeply inclined medium-thick coal seam mining faces are still at a certain angle to the horizontal plane and are in a non-horizontal state, making the equipment in the working face extremely prone to overturning and sliding.

[0005] Secondly, coal in the goaf formed after mining is prone to spontaneous combustion;

[0006] Third, after the mining of steeply inclined medium-thick coal seams, the rock strata above the coal seam collapse and move, resulting in a redistribution of the stress field, which makes the maintenance of the roof roadway difficult. In addition, when mining steeply inclined medium-thick coal seams, it is usually necessary to excavate two roadways, and the amount of roadway excavation work is large.

[0007] In conclusion, the aforementioned existing technologies still require further improvement. Summary of the Invention

[0008] The purpose of this invention is to provide a method for leaving a roadway in the mining of a single steeply inclined medium-thick coal seam by top coal caving. Based on the excavation of one roadway, this method combines the layout of the roadway before and after the horizontal top coal caving of the steeply inclined medium-thick coal seam with the change of wind direction in the goaf. This can prevent spontaneous combustion of coal in the goaf, reduce the amount of roadway excavation, avoid the impact of the overlying rock strata on the roadway, and ensure full-pressure ventilation at the working face.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving, comprising the following steps:

[0011] S1. Divide the coal seam into several segments along the dip direction of the steeply dipping, medium-thick coal seam, with only one roadway in each segment.

[0012] S2. Tunneling is carried out horizontally along the true thickness of the steeply dipping, medium-thick coal seam. The cross-sectional shape of the tunnel after tunneling is a right-angled trapezoid, which includes the following sub-steps:

[0013] S21. Advance horizontally a meters from the top of the steeply inclined medium-thick coal seam to the bottom of the steeply inclined medium-thick coal seam.

[0014] S22. Following step S21, continue to advance b meters horizontally into the bottom rock of the steeply dipping medium-thick coal seam to form the upper base of a right trapezoid, with a side length of a+b meters.

[0015] S23, vertically downward advance c meters;

[0016] S24. Advance horizontally towards the roof of the steeply dipping, medium-thick coal seam by a+c / tanα+b meters until the cross-sectional shape of the roadway is a right trapezoid, where α is the dip angle of the coal seam.

[0017] S3. After the tunnel is formed, temporary support is provided for it;

[0018] S4. The tunnel continues to be excavated from the transport uphill direction to the return air uphill direction until the tunnel connects the transport uphill and return air uphill directions.

[0019] S5. After the tunnel excavation is completed, hydraulic supports are installed to support it, and a rockfall curtain is fixed on the tunnel floor to prevent the gangue from falling into the tunnel.

[0020] S6. Advance along the center line of the roadway, and arrange grouting pipes in the goaf area formed after the advancement. The grouting pipes are arranged from top to bottom, forming grouting areas in the upper, middle and lower parts of the goaf respectively. After grouting, a windbreak curtain is formed in the goaf.

[0021] S7. Hang a windbreak inside the rock curtain to preserve the tunnel in the rock strata and form a return air passage.

[0022] The beneficial technical effects directly brought about by the above technical solution are as follows:

[0023] By laying out the roadway before horizontal top coal caving in a steeply inclined medium-thick coal seam, and leaving a return air roadway behind the working face after horizontal top coal caving in a steeply inclined medium-thick coal seam, this roadway leaving method can effectively ensure the leaving of the roadway behind the working face of a single steeply inclined medium-thick coal seam top coal caving working face, ensure that the working face has two safe exits, ensure full air pressure ventilation of the working face, and reduce the amount of roadway excavation.

[0024] As a preferred embodiment of the present invention, after the roadway is formed, metal mesh with a meter and b meter widths is laid on the coal seam part and rock stratum part of the upper bottom edge of the roadway, respectively. The metal mesh in the coal seam roadway is fixed in the coal seam by anchor bolts; a truss support is set below the metal mesh in the rock stratum roadway, and both ends of the truss support are fixed by anchor cables, and the other ends of the anchor cables are fixed in the rock stratum.

[0025] As another preferred embodiment of the present invention, the angle between the anchor cable and the truss support is α / 2 to 2α / 3.

[0026] Furthermore, in step S5, the hydraulic support is located in the coal seam roadway, and the metal mesh on top of the hydraulic support is removed in advance before coal is discharged.

[0027] Furthermore, a grouting pipe is installed in the upper, middle and lower parts of the goaf, with an interval of 5 to 10 meters between adjacent grouting pipes.

[0028] Furthermore, during grouting, grout is first injected into the grouting pipe at the top of the goaf, then into the grouting pipe in the middle of the goaf, and finally into the grouting pipe at the bottom of the goaf.

[0029] Furthermore, the windproof material is a windproof canvas.

[0030] Furthermore, each grouting pipe is equipped with several grout outlets.

[0031] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0032] This invention proposes a method for leaving a roadway in a single steeply inclined, medium-thick coal seam with top-coal caving. The roadway is excavated horizontally along the true thickness of the steeply inclined, medium-thick coal seam, resulting in a right-angled trapezoidal roadway. After the coal seam is excavated, the reserved roadway space continues to be excavated along the coal seam floor. A truss support is installed on the roof of the reserved roadway, with both ends anchored to the rock strata of the coal seam floor using long anchor cables. The reserved roadway has two sides: one side is rock strata, and the other is a windbreak canvas. The upper end of the windbreak canvas is fixed to the truss support on the roof, and the lower end is fixed to the roadway floor, thus forming a return air passage. A gangue curtain is installed on the outside of the windbreak canvas to prevent gangue from the goaf from entering the reserved roadway. To prevent wind from entering the goaf, grouting pipes are installed in the goaf, located in the upper, middle, and lower spaces, with each grouting pipe having multiple grout outlets. After the cement slurry is injected into the goaf, it forms a windbreak curtain, thereby changing the wind direction entering the goaf and allowing the polluted air behind the working face to be discharged along the reserved roadway.

[0033] This invention makes full use of the natural angle of repose of the bottom strata of steeply inclined medium-thick coal seams, and reserves roadways for safe and stable arrangement in the strata.

[0034] The present invention uses a combination of truss supports and anchor cables to maintain the reserved roadway, which facilitates construction and results in a good roadway formation effect.

[0035] Compared with traditional steeply inclined medium-thick coal seam mining methods under the same conditions, the single steeply inclined medium-thick coal seam top coal caving mining method proposed in this invention reduces the number of rock tunnels to be excavated, and has the advantages of small excavation volume, low investment, and good economic benefits.

[0036] The present invention uses windbreak curtains and windbreak canvases in the goaf area to change the wind direction, prevent fresh air from entering the goaf area, prevent spontaneous combustion of residual coal, and avoid air leakage. Attached Figure Description

[0037] The present invention will be further described below with reference to the accompanying drawings:

[0038] Figure 1 This is a schematic diagram of the tunnel cross-section layout of the present invention;

[0039] Figure 2 This is a schematic diagram of the working surface arrangement of the present invention;

[0040] Figure 3 The main illustration shows a schematic diagram of the structure of the windbreak curtain of the present invention;

[0041] Figure 4 The main illustration shows a schematic diagram of the grouting pipe of the present invention;

[0042] In the picture:

[0043] 1. Coal seam roof, 2. Steeply inclined medium-thick coal seam, 3. Coal seam floor, 4. Anchor cable, 5. Truss support, 6. Anchor bolt, 7. Grouting pipe, 8. Gangue curtain, 9. Windproof canvas, 10. Coal seam dip angle α, 11. Transport uphill, 12. Return air uphill, 13. Roadway, 14. Working face advance direction, 15. Windproof curtain, 16. Goaf, 17. Fresh air flow direction, 18. Sewage air flow direction, 19. Grout outlet. Detailed Implementation

[0044] This invention proposes a method for leaving a roadway in the top coal caving mining of a single steeply inclined medium-thick coal seam. In order to make the advantages and technical solutions of this invention clearer and more explicit, the invention will be further described below with reference to specific embodiments.

[0045] The technical concept of this invention utilizes the coal seam angle α after mining a steeply inclined, medium-thick coal seam to construct a right-angled trapezoidal roadway. By rationally setting the side lengths of each side of the right-angled trapezoidal roadway, grouting pipes are laid in the goaf area formed after the working face advances to further form a windbreak curtain. Combining these two aspects, a roadway retention method based on the coal seam floor can be realized. The advantages it can achieve are: reducing the amount of roadway excavation (only one roadway is needed, which, combined with the roadway retention method of this invention, can achieve the function of two roadways in the prior art), avoiding the impact of the overlying rock strata in the goaf on the roadway, ensuring full-pressure ventilation of the working face, and preventing spontaneous combustion of coal in the goaf.

[0046] The formulation and preparation method of the grout injected into the grouting pipe described in this invention can be implemented by those skilled in the art by referring to existing technologies.

[0047] like Figure 1 As shown in the schematic diagram of the roadway cross-section of the present invention, it illustrates the coal seam roof 1, steeply inclined medium-thick coal seam 2, coal seam floor 3, anchor cable 4, truss support 5, anchor bolt 6, grouting pipe 7, rockfill curtain 8, windbreak canvas 9, and coal seam dip angle α10; wherein, the anchor cable, truss support, and anchor bolt are used to support the roadway, the grouting pipe is located in the goaf, and the main functions of the rockfill curtain and windbreak canvas are to block rock and wind, and their structure can be based on existing technology.

[0048] like Figure 2 As shown in the schematic diagram of the working face layout of the present invention, it shows the transport uphill 11, return air uphill 12, roadway 13, working face advance direction 14, windbreak curtain 15, goaf 16, fresh air flow direction 17, and polluted air flow direction 18.

[0049] The present invention will now be described in detail with reference to specific embodiments.

[0050] A method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving includes the following steps:

[0051] Step 1: Divide the coal seam into several segments along the dip direction of the steeply inclined medium-thick coal seam, with only one roadway in each segment; by setting only one roadway, this roadway cooperates with the right-angled trapezoidal roadway and windbreak curtain behind it, with both air inlets and outlets, to ensure full air pressure ventilation at the working face and reduce the amount of roadway excavation.

[0052] Step 2: Excavate the roadway horizontally along the true thickness of the steeply dipping, medium-thick coal seam. The cross-sectional shape of the excavated roadway will be a right-angled trapezoid. This step includes the following sub-steps:

[0053] Advance horizontally a meters from the roof of the steeply inclined medium-thick coal seam to the floor of the steeply inclined medium-thick coal seam.

[0054] Continue advancing b meters along the horizontal line into the bottom rock of the steeply dipping, medium-thick coal seam, forming the upper base of a right trapezoid with a side length of a+b meters;

[0055] Advance vertically downwards by c meters;

[0056] Advance horizontally towards the roof of the steeply dipping, medium-thick coal seam by a+c / tanα+b meters until the cross-sectional shape of the roadway is a right trapezoid, where α is the dip angle of the coal seam.

[0057] Step 3: After the roadway is formed, temporary support is provided. A metal mesh of a meter and b meter width is laid on the coal seam and rock strata sections of the upper and lower sides of the roadway, respectively. The metal mesh in the roadway is fixed to the coal seam with anchor bolts. A truss support is set below the metal mesh in the rock strata roadway. Both ends of the truss support are fixed with anchor cables, and the other ends of the anchor cables are fixed to the rock strata. The angle between the anchor cables and the truss support is α / 2 to 2α / 3.

[0058] Step 4: The tunnel continues to be excavated from the transport uphill direction to the return air uphill direction until the tunnel connects the transport uphill and return air uphill directions.

[0059] Step 5: After the roadway excavation is completed, hydraulic supports are installed to support it. The hydraulic supports are located at the bottom of the upper bottom edge of the coal seam roadway. Before coal is released, the hydraulic supports and the metal mesh located at the upper bottom edge of the coal seam are removed in advance. A gangue curtain is fixedly installed on the roadway floor to prevent gangue from falling into the goaf and entering the roadway.

[0060] Step 6: Advance along the center line of the roadway. After advancement, grouting pipes are arranged in the goaf area. The grouting pipes are arranged from top to bottom, forming grouting areas in the upper, middle and lower parts of the goaf. During grouting, grout is first injected into the grouting pipes in the upper part of the goaf, then into the grouting pipes in the middle part of the goaf, and finally into the grouting pipes in the lower part of the goaf. The interval between adjacent grouting pipes is 5 to 10 meters. After grouting, a windbreak curtain is formed in the goaf.

[0061] Step 7: Hang a windbreak inside the rock curtain to preserve the tunnel in the rock strata and form a return air channel.

[0062] Several grout outlet holes 19 are provided on each of the above-mentioned grouting pipes.

[0063] The present invention will be further described below with reference to specific embodiments.

[0064] Example 1:

[0065] Combination Figures 1 to 3As shown, this invention relates to a method for pre-reserved roadway in a single steeply inclined medium-thick coal seam top-coal caving mining. The roadway is excavated horizontally along the true thickness of the steeply inclined medium-thick coal seam, resulting in a right-angled trapezoidal roadway. After the coal seam is excavated, the reserved roadway continues to be excavated along the direction of the coal seam floor. A truss support 5 is installed on the roof of the reserved roadway, with both ends anchored to the rock strata 3 of the coal seam floor using long anchor cables 4. The reserved roadway has two sides: one side is rock strata, and the other side is a windbreak canvas 9. The upper end of the windbreak canvas is fixed to the truss support on the roof, and the lower end is fixed to the roadway floor, thus forming a return air passage. A gangue curtain 8 is installed on the outside of the windbreak canvas to prevent gangue from the goaf from entering the reserved roadway. To prevent wind from entering the goaf, grouting pipes 7 are installed every 5-10 meters in the goaf, located at the upper, middle, and lower spatial positions. Each grouting pipe has multiple grout outlet holes 19. After the cement slurry is injected into the goaf, it forms a windbreak curtain, thereby changing the wind direction entering the goaf and allowing the polluted air behind the working face to be discharged along the reserved roadway.

[0066] The length of the upper base of the right-angled trapezoidal roadway is a+b, where a is the horizontal distance of the true thickness of the steeply inclined medium-thick coal seam, and b is the reserved width of the roadway roof; the height of the right-angled trapezoidal roadway is c; the length of the lower base of the right-angled trapezoid is a+c / tanα+b, where α is the dip angle of the coal seam.

[0067] The angle between the long anchor cable and the horizontal plane is α / 2 to 2α / 3. The reserved roadway is located on the bottom of the coal seam, which can avoid the impact of the overlying strata in the goaf.

[0068] Specific steps:

[0069] Step 1: Divide the coal seam into several segments along the dip direction of the steeply dipping, medium-thick coal seam, with only one roadway laid out in each segment;

[0070] Step 2: Tunneling is carried out in the coal and rock along the horizontal direction of the true thickness of the steeply inclined medium-thick coal seam. The tunnel shape is a right trapezoid.

[0071] Step 3: Advance horizontally from the top of the coal seam to the bottom of the coal seam by a meter; then, continue to advance horizontally into the rock of the bottom of the coal seam by b meters, forming the upper base of a right trapezoid (a+b meters); then, advance vertically downward by c meters; advance horizontally towards the top of the coal seam by a+c / tanα+b meters until the cross-section of the roadway is a right trapezoid.

[0072] Step 4: After the roadway is formed, metal mesh with widths of 'a' and 'b' meters is laid on the coal seam section and the rock stratum section, respectively, at the top and bottom edges. In the coal seam roadway, the metal mesh is temporarily supported by anchor bolts fixed to the coal seam; in the rock stratum roadway, a truss support is simultaneously installed below the metal mesh, with both ends of the truss support fixed by anchor cables, the other end of which is fixed to the rock stratum. The angle between the anchor cable and the truss support is α / 2 to 2α / 3.

[0073] Step 5: The right-angled trapezoidal tunnel continues to be excavated from the transport uphill direction to the return air uphill direction until the right-angled trapezoidal tunnel connects the transport uphill 11 and the return air uphill 12;

[0074] Step Six: After the right-angled trapezoidal roadway is excavated, a high-level hydraulic support for roof coal caving is installed below the upper and lower edges of the coal seam roadway. Before caving the coal, the temporary metal mesh laid in front of the support and on the roof of the coal seam is removed in advance. At the same time, a rock-blocking curtain is suspended at one end of the truss support in advance. The rock-blocking curtain is fixed in the roadway floor, preferably by anchoring.

[0075] Step 7: Advance the working face in the direction of 14. After the working face advances, use grouting pipes to perform high-level, mid-level, and low-level grouting in the goaf every 5 to 10 meters to form a windbreak curtain 15.

[0076] Step 8: After the windbreak curtain is formed, a windbreak canvas is hung inside the rock curtain and fixed to the tunnel floor; thus, the tunnel in the rock strata is preserved, forming a return air passage.

[0077] In summary, this invention can prevent fresh airflow from entering the goaf and prevent spontaneous combustion of coal.

[0078] Any parts not mentioned in this invention can be achieved by referring to existing technologies.

[0079] It should be noted that any equivalent or obvious modifications made by those skilled in the art under the guidance of this specification should be within the scope of protection of this invention.

Claims

1. A method for leaving a roadway during top-coal caving mining of a single steeply inclined medium-thick coal seam, characterized in that, The steps are as follows: S1. Divide the coal seam into several segments along the dip direction of the steeply dipping, medium-thick coal seam, with only one roadway in each segment. S2. Tunneling is carried out horizontally along the true thickness of the steeply dipping, medium-thick coal seam. The cross-sectional shape of the tunnel after tunneling is a right-angled trapezoid, which includes the following sub-steps: S21. Advance horizontally a meters from the top of the steeply inclined medium-thick coal seam to the bottom of the steeply inclined medium-thick coal seam. S22. Following step S21, continue to advance b meters horizontally into the bottom rock of the steeply dipping medium-thick coal seam to form the upper base of a right trapezoid, with a side length of a+b meters. S23, vertically downward advance c meters; S24. Advance horizontally towards the roof of the steeply dipping, medium-thick coal seam by a+c / tanα+b meters until the cross-sectional shape of the roadway is a right trapezoid, where α is the dip angle of the coal seam. S3. After the tunnel is formed, temporary support is provided for it; S4. The tunnel continues to be excavated from the transport uphill direction to the return air uphill direction until the tunnel connects the transport uphill and return air uphill directions. S5. After the tunnel excavation is completed, hydraulic supports are installed to support it, and a rockfall curtain is fixed on the tunnel floor to prevent the gangue from falling into the tunnel. S6. Advance along the center line of the roadway, and arrange grouting pipes in the goaf area formed after the advancement. The grouting pipes are arranged from top to bottom, forming grouting areas in the upper, middle and lower parts of the goaf respectively. After grouting, a windbreak curtain is formed in the goaf. S7. Hang a windbreak inside the rock curtain to preserve the tunnel in the rock strata and form a return air passage.

2. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 1, characterized in that: After the roadway is formed, metal mesh with a meter and b meter widths is laid on the coal seam part and rock stratum part of the upper bottom edge of the roadway, respectively. The metal mesh in the coal seam roadway is fixed in the coal seam with anchor bolts; a truss support is set below the metal mesh in the rock stratum roadway. The two ends of the truss support are fixed by anchor cables, and the other ends of the anchor cables are fixed in the rock stratum.

3. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 2, characterized in that: The angle between the anchor cable and the truss support is α / 2 to 2α / 3.

4. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 2, characterized in that: In step S5, the hydraulic support is located in the coal seam roadway, and the metal mesh on top of the hydraulic support is removed in advance before coal is discharged.

5. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 2, characterized in that: A grouting pipe is installed in the upper, middle and lower parts of the goaf, with an interval of 5 to 10 meters between adjacent grouting pipes.

6. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 5, characterized in that: During grouting, grout is first injected into the grouting pipe at the top of the goaf, then into the grouting pipe in the middle of the goaf, and finally into the grouting pipe at the bottom of the goaf.

7. The method for leaving a roadway in a single steeply inclined medium-thick coal seam top coal caving mining according to claim 1, characterized in that: The windbreak material is a windbreak canvas.

8. The method for leaving a roadway in a single steeply inclined medium-thick coal seam with top coal caving as described in claim 5, characterized in that: Each grouting pipe is equipped with several grout outlets.

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