Underlying room-pillar type goaf treatment method for overhead mining

Abstract

A method for treating an underlying room-and-pillar goaf in overhead mining comprises the steps that fine detection is conducted on the goaf below a working face, the position of the room-and-pillar goaf is determined, and a tunneling roadway is planned in the position, corresponding to a room-and-pillar, in an upper coal seam; performing advanced drilling arrangement and advanced filling planning on the corresponding goaf below the roadway; according to the sequence that the corresponding goaf below the roadway is firstly filled in advance and then roadway tunneling is carried out, roadway tunneling work is carried out forwards; working face filling drill hole arrangement and grouting filling operation are conducted on the corresponding goaf below the working faces on the two sides in the roadway; and the filling effect is detected and analyzed, if the requirement is not met, the reason is analyzed, and supplementary grouting is conducted after construction errors are corrected. According to the method, the tunneling roadway is planned at the position, corresponding to the room pillar, of the upper coal seam above the goaf, the drill holes are formed in the roadway towards the goaf below the working faces on the two sides, grouting filling operation is conducted, and treatment of the underlying room pillar type goaf is achieved underground.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a method for managing a room-and-pillar goaf area under goaf mining. Background Art

[0002] Early room-and-pillar mining mainly mined coal seams with simple geological mining conditions and easy to mine. With the development of coal mining processes and technologies, coal mines now mainly adopt comprehensive mechanized coal mining methods. The room-and-pillar goaf formed in the early days will cause safety hazards to the mining of adjacent upper and lower coal seams. There are safety hazards of stepping on the air when mining the upper coal seams. When mining the lower coal seams, the hydraulic support will inevitably be subjected to the concentrated pressure of point loads, which is extremely unfavorable for the support of the working face roof and is prone to roof collapse accidents.

[0003] At present, the filling of goaf mainly includes in-situ filling in the goaf and surface hole grouting filling. When in-situ filling is adopted, since the room-and-pillar goaf was mined and dug randomly in the past without any rules, whether it would collapse, contain toxic and harmful gases, or catch fire is unknown, after the goaf is opened, it is extremely difficult to enter the goaf for support and ventilation. After ventilation, it is very easy to cause spontaneous combustion of the coal residue, which poses a great safety hazard.

[0004] When surface drilling and grouting filling is adopted, a large amount of road construction is required due to the great influence of surface undulation, and there are problems such as difficulty in transporting grouting materials, difficulty in building grouting stations, difficulty in laying grouting pipelines, difficulty in ground surface mapping, and high construction costs.

[0005] Therefore, the present invention provides a method for managing the underlying room-and-pillar goaf area in goaf mining, so as to solve the problems arising in the above method. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To achieve the above object, the present invention proposes a method for managing the room-and-pillar goaf area under the goaf mining, comprising the following steps:

[0008] S1. Conduct detailed detection of the distribution characteristics of the goaf below the working face, determine the location of the room-and-pillar goaf, and plan the excavation tunnels in the upper coal seam corresponding to the room-and-pillar locations;

[0009] S2. According to the planned tunnel range, advance drilling arrangement and advance filling planning are carried out for the corresponding goaf below the tunnel;

[0010] S3, advance the tunnel excavation work in the order of first filling the corresponding goaf below the tunnel and then excavating the tunnel;

[0011] S4. Arrange the working face filling drilling holes and perform grouting filling operations in the corresponding goaf areas below the working faces on both sides of the tunnel;

[0012] S5. Test and analyze the filling effect. If it does not meet the requirements, analyze the reasons and perform additional grouting after correcting the construction errors.

[0013] The present invention plans an excavation tunnel in the upper coal seam above the goaf corresponding to the room-pillar position, realizes stable tunneling of the tunnel through advance filling, arranges drilling holes in the goaf below the working faces on both sides of the tunnel and performs grouting filling operations, thereby realizing the management of the underlying room-pillar goaf in the mine.

[0014] Optionally, when detecting the distribution characteristics of the goaf in S1, it is necessary to understand the location, depth, space size and internal room-pillar distribution characteristics of the goaf, so that the tunnel can be planned above the room-pillar to ensure that the tunnel excavation of the working face can be adequately supported.

[0015] Further, in S1, the planned excavation tunnel includes tunnel dimensions and tunnel excavation speed;

[0016] When planning the tunnel dimensions, it is necessary to meet the space requirements for the construction of the underlying room-and-pillar goaf drilling equipment and paste filling equipment while ensuring the safety of the roof control;

[0017] The tunnel excavation speed needs to take into account the advance filling. Tunnel excavation can only be carried out after the advance filling area in front of the tunnel excavation has been filled and solidified.

[0018] Furthermore, in S2, based on the detection of the position of the room pillar, the advance drilling during the tunnel excavation is planned, and the advance drilling planning includes:

[0019] A No. 1 advance borehole is set along the direction of the tunnel and at an acute angle to the tunnel surface;

[0020] A plurality of groups of No. 2 advance drill holes are set at the edges of both sides of the tunnel, and the No. 2 advance drill holes are set at an acute angle with the tunnel edge in the horizontal direction;

[0021] The No. 1 advance drilling hole and the No. 2 advance drilling hole are located in the same inclined plane and are arranged in a fan shape.

[0022] Furthermore, grouting is carried out on the lower goaf near the room pillar through the No. 1 advance drilling hole, and the room pillar goaf structure directly below the tunnel is reinforced by grouting to form the main structure of the advance grouting;

[0023] Through the No. 2 advance drilling hole, grouting operations are carried out in the goaf below corresponding to the edge of the tunnel to form an auxiliary support structure for the main structure of the advance grouting.

[0024] Furthermore, in said S3, when arranging the working face filling drilling holes, it includes:

[0025] Multiple groups of No. 3 drill holes are symmetrically arranged on both sides of the tunnel, and the multiple groups of No. 3 drill holes are symmetrically arranged in the same plane perpendicular to the tunnel excavation direction and are arranged in a fan shape;

[0026] Moreover, borehole No. 3 is far away from the advance borehole and penetrates into the goaf below corresponding to the working faces on both sides of the tunnel.

[0027] Furthermore, the construction point of the filling drilling of the working face and the construction point of the advance drilling are in the same vertical plane;

[0028] The spacing between each drilling construction point is determined based on parameters such as drilling direction, inclination, paste diffusion radius, etc. A 90% reduction is made on the basis of the spacing between drilling construction points calculated based on the above parameters to ensure that there will be no leakage in the goaf.

[0029] Furthermore, when conducting advance drilling arrangement or working face drilling arrangement, it is necessary to reduce the suspended distance between the excavation working face and the hole filling space while ensuring the hole filling construction space to reduce the risk of roof cap falling.

[0030] Furthermore, the filling material uses gangue as aggregate to absorb the coal gangue generated during the washing process;

[0031] Prepare a paste material with a mass concentration greater than 80% as a grouting filling material, and the grouting material must have balanced pumpability, stability, plasticity and fluidity;

[0032] After the gangue is screened and crushed on the ground and the paste is prepared, it is transported to the underground conversion station through a pipeline. The grouting material is supplied to the tunnel through the underground conversion station to complete the grouting operation in the goaf.

[0033] Further, in said S5, the detection and analysis of the filling effect includes the detection and analysis of the filling effect of the advance drilling and the detection and analysis of the filling effect of the working face drilling, and the analysis process includes intermediate detection and acceptance detection;

[0034] Intermediate testing: During the filling process, every time a certain amount of filling is done, the filling paste is sampled and tested to analyze the paste's solidity rate, water seepage rate, mass concentration and slump, and real-time feedback is provided based on the test results;

[0035] Acceptance test: after the paste filling material is finally solidified, drill out the solidified filling material to obtain the solidity rate, porosity and mechanical properties of the material, so as to analyze whether the filling body is connected to the top, whether it meets the requirements of filling the underlying goaf, and whether it meets the supporting performance indicators of the coal seam in the underlying goaf;

[0036] If the requirements are not met, the reasons for analysis include:

[0037] Whether the paste ratio mass concentration is low, resulting in high paste bleeding rate;

[0038] Insufficient grouting pressure results in a small paste diffusion radius;

[0039] Insufficient amount of gel material results in insufficient mechanical properties.

[0040] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0042] Figure 1 It is a schematic diagram of the method steps of a method for treating a room-and-pillar goaf area under goaf mining according to the present invention;

[0043] Figure 2 A schematic diagram of the three-dimensional structure of the arrangement of the tunnel hole filling and grouting drilling holes in a method for treating the room-and-pillar goaf area under the goaf mining according to the present invention;

[0044] Figure 3 It is a schematic diagram of the main structure of the arrangement of the tunnel hole filling and grouting drilling holes for a method for treating the room-and-pillar goaf area under the goaf mining according to the present invention;

[0045] Figure 4 It is a left-view structural schematic diagram of the arrangement of tunnel hole filling and grouting drilling for a method for treating a room-and-pillar goaf area under goaf mining according to the present invention;

[0046] Figure 5 It is a schematic diagram of the top view of the arrangement of the tunnel hole filling and grouting drilling holes for a method for treating the room-and-pillar goaf area under the goaf mining according to the present invention;

[0047] Figure 6 The present invention is a schematic diagram of a grouting filling process flow of a method for managing a room-and-pillar goaf area under goaf mining.

[0048] Description of reference numerals:

[0049] 1. Excavate tunnel; 2. Advance drilling of No. 1 hole; 3. Advance drilling of No. 2 hole; 4. Drilling of No. 3 hole. DETAILED DESCRIPTION

[0050] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0051] At present, the filling of goaf mainly includes in-situ filling within the goaf and surface hole drilling and grouting filling.

[0052] In-situ filling requires the goaf to be sealed and unsealed. After the entire old goaf is supported and ventilated, the goaf cavities are filled from the far end to the near end. Because the room-and-pillar goaf was mined and dug randomly in the past without any rules, whether it would collapse, produce toxic and harmful gases, or catch fire was unknown. After the goaf is sealed, it is extremely difficult to enter the goaf for support and ventilation. After ventilation, it is very easy to cause spontaneous combustion of the coal residue, which poses a great safety hazard.

[0053] Surface hole drilling and grouting filling is a construction method in which a slurry made of materials with specific properties is injected into the goaf and cracks in the foundation rock and soil at a certain pressure through grouting pipes set up through holes in the ground to make it penetrate and fill. After gelling and solidification, the voids are filled or reinforced to achieve the purpose of goaf management. It has the characteristics of being greatly affected by surface undulations, requiring a large amount of road construction, difficulty in transporting grouting materials, difficulty in building grouting stations, difficulty in laying grouting pipelines, difficulty in ground characterization, and high cost.

[0054] In view of the shortcomings of the above methods, the present invention provides a method for treating the room-and-pillar goaf area under the goaf mining. Figures 1 to 6 Elaborate in detail.

[0055] A method for managing a room-and-pillar goaf area under goaf mining comprises the following steps:

[0056] S1. Conduct detailed detection of the distribution characteristics of the goaf below the working face, determine the location of the room-and-pillar goaf, and plan the excavation tunnel 1 in the upper coal seam corresponding to the room-and-pillar location;

[0057] S2. According to the planned tunnel range, advance drilling arrangement and advance filling planning are carried out for the corresponding goaf below the tunnel;

[0058] S3, advance the tunnel excavation work in the order of first filling the corresponding goaf below the tunnel and then excavating the tunnel;

[0059] S4. Arrange the working face filling drilling holes and perform grouting filling operations in the corresponding goaf areas below the working faces on both sides of the tunnel;

[0060] S5. Test and analyze the filling effect. If it does not meet the requirements, analyze the reasons and perform additional grouting after correcting the construction errors.

[0061] The present invention plans a tunnel 1 at the position of the room-pillar corresponding to the upper coal seam above the goaf, realizes stable tunneling of the tunnel by advanced filling, arranges drilling holes in the goaf below the working faces on both sides of the tunnel and performs grouting and filling operations, thereby achieving the management of the underlying room-pillar goaf in the mine. There is no need to open the sealing area and perform filling operations in the goaf as in the local filling method, and at the same time avoids various difficulties existing in the surface hole making and grouting filling method.

[0062] In S1, when detecting the distribution characteristics of the goaf, it is necessary to understand the location, depth, space size and internal room-pillar distribution characteristics of the goaf, so that the tunnel can be planned above the room-pillar to ensure that the working face tunnel excavation can be adequately supported.

[0063] The layout of the upper coal seam roadway and working face is planned according to the distribution characteristics of the goaf, so that the roadway is located at the room-pillar position of the lower room-pillar goaf, ensuring that the upper coal seam roadway receives sufficient support, and helping the drilling to better play the grouting function, so as to maximize the range of the roadway drilling that can cover the lower room-pillar goaf and ensure that the room-pillar goaf is fully filled.

[0064] Furthermore, in S1, the planning of the excavation tunnel 1 includes the tunnel size and the tunnel excavation speed;

[0065] When planning the tunnel dimensions, it is necessary to meet the space requirements for the construction of the underlying room-and-pillar goaf drilling equipment and paste filling equipment while ensuring the safety of the roof control;

[0066] The tunneling speed needs to take into account the advance filling. The tunneling can only be carried out after the advance filling area in front of the tunneling has been filled and solidified. This ensures that the goaf below the tunneling direction has been filled and solidified to produce support strength, so as to ensure that the tunneling work will not be affected by the underlying goaf.

[0067] In S2, based on the detection of the position of the room pillar, the advance drilling during tunnel excavation is planned. The advance drilling planning includes:

[0068] A No. 1 advance borehole 2 is arranged along the direction of the tunnel and at an acute angle to the tunnel surface;

[0069] A plurality of groups of No. 2 advanced drilling holes 3 are arranged at the edges of both sides of the tunnel, and the No. 2 advanced drilling holes 3 are arranged to form an acute angle with the tunnel edge in the horizontal direction;

[0070] The first advance borehole 2 and the second advance borehole 3 are arranged in the same inclined plane in a fan-shaped arrangement. The fan-shaped arrangement can expand the grouting range as much as possible, ensure that the grouting range of each borehole can be used to the maximum extent, and ensure that the room-and-pillar goaf below the working face of the tunnel 1 is full and substantial.

[0071] After the advance drilling is completed, grouting operations are carried out in the No. 1 advance drilling hole 2 and the No. 2 advance drilling hole 3. Grouting is carried out in the lower layer goaf near the room pillar through the No. 1 advance drilling hole 2, and the room pillar goaf structure directly below the roadway is reinforced by grouting to form the main structure of the advance grouting;

[0072] Through the No. 2 advance drilling hole 3, grouting operation is carried out in the goaf below corresponding to the edge of the tunnel to form an auxiliary support structure for the main structure of the advance grouting.

[0073] The composition of the advance grouting main structure and the auxiliary support structure can form a support range slightly larger than the coverage range of the tunneling tunnel 1 below the working face of the tunneling tunnel 1, thereby achieving more stable support for the tunneling tunnel 1 and ensuring that the underlying room-pillar goaf area in front of the tunnel excavation is in a full state.

[0074] In S3, the work face filling drilling arrangement includes:

[0075] The multiple groups of No. 3 boreholes 4 are symmetrically arranged on both sides of the tunnel. The multiple groups of No. 3 boreholes 4 are symmetrically arranged in the same plane perpendicular to the tunnel excavation direction and are arranged in a fan shape. The fan shape arrangement can expand the grouting range as much as possible, ensure that the grouting range of each borehole can be used to the maximum extent, and ensure that the room-and-pillar goaf below the mining working surface on both sides of the tunnel is full and substantial.

[0076] The third borehole 4 is far away from the advance borehole and goes deep into the goaf below the working faces on both sides of the tunnel. There is a certain angle between the third borehole 4 and the second advance borehole 3, so as to ensure that the third borehole 4 can go deep into the goaf below the mining working face.

[0077] In some embodiments, the construction point of the work surface filling drilling and the construction point of the advance drilling are in the same vertical plane, which facilitates the staff to plan the coverage range between the drilling holes;

[0078] The spacing between each drilling construction point is determined based on parameters such as drilling direction, inclination, paste diffusion radius, etc. A 90% reduction is made on the basis of the spacing between drilling construction points calculated based on the above parameters to ensure that there will be no leakage in the goaf.

[0079] In some embodiments, when performing advance drilling arrangement or working face drilling arrangement, it is necessary to reduce the suspended distance between the excavation working face and the hole filling space while ensuring the hole filling construction space to reduce the risk of roof cap falling.

[0080] In this embodiment, the filling material used in the filling operation is mixed on the ground, wherein gangue is selected as aggregate to absorb the coal gangue generated in the washing process, and a certain proportion of cementitious material is added to carry out a paste filling material ratio test, and the paste material is selected as the grouting filling material according to the experimental results;

[0081] The paste material requires a mass concentration greater than 80%, and the grouting material must have balanced pumpability, stability, plasticity and fluidity;

[0082] The gangue is screened and crushed on the ground, and then screened after crushing. The qualified gangue is stored, and the unqualified gangue is recycled. The qualified gangue, cementitious materials and water are weighed in a certain proportion and put into the mixer to mix and prepare the paste. After the preparation of the paste is completed, it is transported to the underground conversion station through a pipeline, and the grouting material is supplied to the tunnel through the underground conversion station to complete the grouting operation of the goaf.

[0083] After the paste is mixed to meet the requirements, it is transported to the underground conversion station through the filling pump and the ground pipeline, and then pumped to the filling operation area by the underground conversion station and filled into the room-and-pillar goaf, completing the entire grouting filling process.

[0084] In S5, the filling effect detection and analysis includes the filling effect detection and analysis of the advance drilling hole and the filling effect detection and analysis of the working face drilling hole, and the analysis process includes intermediate detection and acceptance detection;

[0085] Intermediate testing: During the filling process, sample the filled paste for testing after each certain amount of filling, analyze the paste's solidification rate, water seepage rate, mass concentration and slump, provide real-time feedback based on the test results, and analyze whether the mechanical properties of the paste after solidification meet the requirements;

[0086] Acceptance test: after the paste filling material is finally solidified, drill out the solidified filling material to obtain the solidity rate, porosity and mechanical properties of the material, so as to analyze whether the filling body is connected to the top, whether it meets the requirements of filling the underlying goaf, and whether it meets the supporting performance indicators of the coal seam in the underlying goaf, so as to comprehensively determine whether the requirements of upper and lower coal seam mining and residual coal pillar recovery in this coal seam are met;

[0087] If the requirements are not met, the reasons for analysis include:

[0088] Whether the paste ratio mass concentration is low, resulting in high paste bleeding rate;

[0089] Insufficient grouting pressure results in a small paste diffusion radius;

[0090] Insufficient amount of gel material results in insufficient mechanical properties.

[0091] After analyzing the causes, the construction process is corrected and optimized based on the causes, and additional grouting is carried out at the corresponding positions of the drilled samples that do not meet the standards. The additional grouting positions are then analyzed and inspected again according to the above-mentioned intermediate inspection and acceptance inspection process until the requirements are met.

[0092] When all drilling points meet the requirements to ensure that the filling body is connected to the top, the underlying goaf is full and the underlying goaf coal seam support performance index is reached, mining operations can be carried out on the working faces to be mined on both sides of the tunnel 1. In addition, during the mining process, the monitoring of the movement of the top and bottom rock layers and stress changes should be strengthened to prevent accidents.

[0093] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0094] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0095] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0096] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0097] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0098] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for managing the room-and-pillar goaf area under the goaf mining, characterized in that: The following steps are involved: S1. Conduct detailed detection of the distribution characteristics of the goaf below the working face, determine the location of the room-and-pillar goaf, and plan the excavation tunnels in the upper coal seam corresponding to the room-and-pillar locations; S2. According to the planned tunnel range, advance drilling arrangement and advance filling planning are carried out for the corresponding goaf below the tunnel; S3, advance the tunnel excavation work in the order of first filling the corresponding goaf below the tunnel and then excavating the tunnel; S4. Arrange the working face filling drilling holes and perform grouting filling operations in the corresponding goaf areas below the working faces on both sides of the tunnel; S5. Test and analyze the filling effect. If it does not meet the requirements, analyze the reasons and perform additional grouting after correcting the construction errors.

2. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: When detecting the distribution characteristics of the goaf in S1, it is necessary to understand the location, depth, space size and internal room-pillar distribution characteristics of the goaf, so that the tunnel can be planned above the room-pillar to ensure that the tunnel excavation of the working face can be adequately supported.

3. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: In S1, the planned excavation roadway includes the roadway size and the roadway excavation speed; When planning the tunnel dimensions, it is necessary to meet the space requirements for the construction of the underlying room-and-pillar goaf drilling equipment and paste filling equipment while ensuring the safety of the roof control; The tunnel excavation speed needs to take into account the advance filling. Tunnel excavation can only be carried out after the advance filling area in front of the tunnel excavation has been filled and solidified.

4. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 2, characterized in that: In S2, based on the detection of the position of the room pillar, the advance drilling during the tunnel excavation is planned, and the advance drilling planning includes: A No. 1 advance borehole is set along the direction of the tunnel and at an acute angle to the tunnel surface; A plurality of groups of No. 2 advance drill holes are set at the edges of both sides of the tunnel, and the No. 2 advance drill holes are set at an acute angle with the tunnel edge in the horizontal direction; The No. 1 advance drilling hole and the No. 2 advance drilling hole are located in the same inclined plane and are arranged in a fan shape.

5. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 4, characterized in that: Grouting is carried out in the lower goaf area near the room pillars through the No. 1 advance drilling hole, and the goaf area structure of the room pillars directly below the tunnel is reinforced by grouting to form the main structure of the advance grouting; Through the No. 2 advance drilling hole, grouting operations are carried out in the goaf below corresponding to the edge of the tunnel to form an auxiliary support structure for the main structure of the advance grouting.

6. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: In S3, when arranging the drilling holes for filling the working face, the following steps are included: Multiple groups of No. 3 drill holes are symmetrically arranged on both sides of the tunnel, and the multiple groups of No. 3 drill holes are symmetrically arranged in the same plane perpendicular to the tunnel excavation direction and are arranged in a fan shape; Moreover, borehole No. 3 is far away from the advance borehole and penetrates into the goaf below corresponding to the working faces on both sides of the tunnel.

7. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: The construction point of the filling drilling of the working surface and the construction point of the advance drilling are in the same vertical plane; The spacing between each drilling construction point is determined based on parameters such as drilling direction, inclination, paste diffusion radius, etc. A 90% reduction is made on the basis of the spacing between drilling construction points calculated based on the above parameters to ensure that there will be no leakage in the goaf.

8. A method for treating room-and-pillar goaf under goaf mining as claimed in any one of claims 1 to 7, characterized in that: When conducting advance drilling arrangement or working face drilling arrangement, it is necessary to reduce the suspended distance between the excavation working face and the hole filling space while ensuring the hole filling construction space to reduce the risk of roof cap falling.

9. A method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: Gangue is selected as the filling material as aggregate to absorb the gangue produced during the washing process; Prepare a paste material with a mass concentration greater than 80% as a grouting filling material, and the grouting material must have balanced pumpability, stability, plasticity and fluidity; After the gangue is screened and crushed on the ground and the paste is prepared, it is transported to the underground conversion station through a pipeline. The grouting material is supplied to the tunnel through the underground conversion station to complete the grouting operation in the goaf.

10. The method for treating room-and-pillar goaf under goaf mining as claimed in claim 1, characterized in that: In S5, the filling effect detection and analysis includes the filling effect detection and analysis of the advance drilling hole and the filling effect detection and analysis of the working face drilling hole, and the analysis process includes intermediate detection and acceptance detection; Intermediate testing: During the filling process, every time a certain amount of filling is done, the filling paste is sampled and tested to analyze the paste's solidity rate, water seepage rate, mass concentration and slump, and real-time feedback is provided based on the test results; Acceptance test: after the paste filling material is finally solidified, drill out the solidified filling material to obtain the solidity rate, porosity and mechanical properties of the material, so as to analyze whether the filling body is connected to the top, whether it meets the requirements of filling the underlying goaf, and whether it meets the supporting performance indicators of the coal seam in the underlying goaf; If the requirements are not met, the reasons for analysis include: Whether the paste ratio mass concentration is low, resulting in high paste bleeding rate; Insufficient grouting pressure results in a small paste diffusion radius; Insufficient amount of gel material results in insufficient mechanical properties.

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