A method for strip pillarless coordinated mining

Abstract

A method for pillarless collaborative mining of a panel includes the following steps: S1, at least three adjacent working faces are arranged sequentially along the strike within the panel, alternating in the order of "wide working face, narrow working face, wide working face"; S2, a narrow working face with a shorter dip length is excavated and mined on one side of the panel; S3, skipping an adjacent wide working face, another narrow working face with a shorter dip length is excavated and mined on the other side of the panel; S4, the goaf areas of the two narrow working faces mined in steps S2 and S3 are handled: firstly, the goaf areas are initially backfilled using the naturally collapsed roof rock caused by mining; then, based on the roof connection of the initial backfill, it is decided whether to supplement backfilling in the unconnected areas to construct artificial backfill support structures on both sides; S5, under the lateral support of the artificial backfill support structures on both sides, the wide working face with a longer dip length located between the two narrow working faces is excavated and mined.

Description

Technical Field

[0001] This invention relates to a method for pillarless collaborative mining in coal mining panels, belonging to the technical field of coal mining methods. Background Technology

[0002] Coal is an important non-renewable energy source and plays a vital role in industrial production. A common coal mining method is underground longwall fully mechanized mining, suitable for the layout of working faces in mining areas and zones. This method typically leaves section pillars, approximately 20 meters wide, between working faces, and the width of these pillars needs to increase with the depth of coal seam mining. For example, with a working face width of 200 meters, if a 20-meter-wide section pillar is left, the coal recovery rate of the entire mining area or zone is only about 90%. Taking a working face recovery length of 1000 meters, a mining height of 5 meters, and a density of 1.5 tons / m³ as an example, approximately 150,000 tons of coal are wasted per working face. Therefore, the method of leaving section pillars in mining involves significant energy waste. Using goaf-side roadway technology can eliminate the need for section pillars or leave only very narrow ones. However, goaf-side roadway support is difficult and maintenance is challenging, and the support difficulty increases with the depth of coal seam mining. Summary of the Invention

[0003] To address the aforementioned problems in existing technologies, this invention provides a panel-based pillarless collaborative mining method, which achieves the goal of improving coal resource recovery rate and reducing resource waste.

[0004] The technical solution of the present invention is as follows: A method for pillarless collaborative mining in a panel, characterized by comprising the following steps: S1. At least three adjacent working faces are arranged sequentially along the direction within the panel area, and the design width of the adjacent working faces is alternately set in the order of "wide working face, narrow working face, wide working face", wherein the two working faces located on the outermost side of the entire panel area direction sequence are wide working faces. S2. Excavate and mine a narrow working face with a relatively short dip length on one side of the panel; S3. Skip an adjacent wide working face and excavate and mine another narrow working face with a shorter dip length on the other side of the panel; S4. Processing the goaf of the two narrow working faces after mining in steps S2 and S3: First, use the naturally collapsed roof rock caused by mining to fill the goaf for the first time; then, depending on the roof connection of the first filling, decide whether to inject filling grout into the non-roofed area to construct the artificial filling body support structure on both sides. S5. Under the lateral support of the artificial backfill support structure on both sides, the wide working face with a long dip length located between two narrow working faces is tunneled and mined. In steps S2 and S3, the tunneling and mining operations in the narrow working face both include the following process steps in sequence: A. Perform hydraulic fracturing in the roof above the mining area of ​​the narrow working face; B. The tunneling process forms a roadway system that serves the narrow working face; C. During the mining process, directional cutting is carried out on the roof; D. Coal is mined from the narrow working face, and the resulting roof collapse fills the goaf with rocks. E. Based on the situation of the roof collapse rock filling and connecting the goaf, supplementary filling is carried out in the unconnected areas to construct a filling body.

[0005] Hydraulic fracturing includes low-level fracturing carried out on the roof of the roadway and high-level fracturing carried out on the roof of the middle area of ​​the working face.

[0006] Step S5 is executed after the filling material constructed in the goaf of the two narrow working faces reaches the predetermined strength.

[0007] Specifically, when the thickness of the coal seam in the panel area is greater than 8 meters, the mining of the narrow working face in steps S2 and S3 only involves mining the bottom of the coal seam, followed by constructing a roof filling body; the mining of the wide working face in step S5 involves whole-seam mining including bottom mining and top caving.

[0008] In this context, each working face within the panel shares or is adjacent to another roadway, and no permanent section coal pillars are left within the panel.

[0009] The filling material used to construct the filling body for the narrow working face includes a compressible phase change material; the compressible phase change material is used to make the filling body exhibit a phased mechanical response when under pressure: in the first pressure stage, it provides a large compressive deformation capacity to achieve close contact with the top, and after reaching a predetermined compressive strain or pressure threshold, it enters the second pressure stage, where its compressive stiffness is significantly improved to provide stable support.

[0010] The compressible phase change material is a composite particle with a brittle outer shell and a compressible core. The composite particle is mixed in the matrix of the filling material at a dosage of 15% to 30% of the total volume of the filling material. In the first pressure stage, the brittle outer shell of the composite particle breaks and the compressible core is compressed, which leads to the compression deformation of the filling material. In the second pressure stage, the composite particle is compacted and the matrix skeleton of the filling material becomes the main load-bearing structure.

[0011] The present invention has the following beneficial effects: Achieving pillarless continuous mining significantly improves resource recovery rate: By optimizing the working face layout and succession sequence, the traditional coal pillars between panels are completely eliminated, increasing the coal resource recovery rate to a higher level, thereby greatly reducing resource loss and significantly enhancing economic benefits.

[0012] This layout and process combination is well adaptable to conditions such as variations in coal seam thickness, high ground stress, and weak roof. By adjusting the working face width and top coal caving strategy, the stress and deformation of the surrounding rock can be actively controlled, effectively preventing disasters such as rock bursts and abnormal gas outbursts. It is especially suitable for safe and efficient mining in disaster-prone mines.

[0013] By utilizing a "wide-narrow-wide" layout and differentiated coal release-backfilling process, the failure of key strata and continuous migration of overburden can be effectively mitigated, thereby significantly reducing the magnitude and extent of surface subsidence caused by mining, reducing the impact on surface buildings and the ecological environment, and conforming to the concept of green mining.

[0014] Adopting the mining sequence of "mining the narrow working faces on both sides first, and then mining the wide working face in the center" is conducive to rapid tunnel excavation and rapid preparation of working faces, shortens the continuity time, improves the continuity and stability of the overall mining of the panel, and provides a systematic guarantee for achieving balanced and efficient production. Attached Figure Description

[0015] Figure 1 This is a top view of the overall application of the disc area of ​​the present invention; Figure 2 This is a cross-sectional view of the overall application of the panel area of ​​the present invention; Figure 3 These are three views of the top plate fracturing of the present invention; Figure 4 These are three views of the top plate cut of the present invention; Figure 5 This is a schematic diagram of the composite particles of the present invention.

[0016] The reference numerals in the figure are as follows: 1. Narrow working face; 2. Wide working face; 3. Artificial filling support structure; 4. Roof; 5. Roadway; 6. Composite particles; 7. Brittle outer shell; 8. Compressible core; 9. Directional cutting; 10. Hydraulic fracturing. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] Please see Figures 1 to 5 The invention provides a technical solution: This invention provides a method for pillarless collaborative mining in a panel, specifically including the following steps: S1. At least three adjacent working faces are arranged sequentially along the direction within the panel area.

[0019] Unlike conventional equal-width or uniform layouts, this method designs the descent lengths of adjacent working faces within the panel area as segmented and differentiated, specifically employing an alternating sequence of "longer-shorter-longer" descent lengths. That is, along the cutting direction, a wide working face 2 with a larger descent length is sequentially set up, followed by a narrow working face 1 with a smaller descent length, and then transitioning to a wide working face 2 with a larger descent length, thus forming a phased layout of "wide-narrow-wide".

[0020] Among them, the two working faces located on the outermost side of the entire panel area's orientation sequence are both wide working faces 2.

[0021] S2. First, excavate and mine a narrow working face 1 with a relatively short dip length on one side of the panel.

[0022] S3. Next, skip the adjacent wide working face 2 and excavate and mine another narrow working face 1 with a shorter dip length on the other side of the panel. The above steps S2 and S3 together constitute the differentiated sequential mining process of "mining the narrower working faces on both sides first".

[0023] In steps S2 and S3, the tunneling and mining operations of the narrow working face 1 both include the following "pressure-tunneling-cutting-mining-injection" process steps in sequence: A. Fracturing: Hydraulic fracturing 10 is performed in the roof 4 above the mining area of ​​the narrow working face 1. This step includes high-level fracturing for the roadway 5 area and low-level fracturing for the mining area. Pre-fracturing allows for more thorough pre-fracture of the roof 4, facilitating more complete filling of the subsequent goaf by collapsed rock and creating favorable conditions for possible grouting. The fracturing process can be flexibly arranged with subsequent tunneling processes; fracturing can be performed first, followed by tunneling, or fracturing and tunneling can be carried out sequentially in cycles depending on the actual working conditions.

[0024] By injecting high-pressure fluid into the roof 5 strata, numerous micro-fractures and macro-cracks are created and expanded within the rock mass. This process significantly reduces the overall strength and integrity of the rock mass, transforming it from a continuous, solid medium into a fragmented structure containing numerous weak surfaces. This pre-damaged state makes roof 5 more susceptible to large-scale, fragmented collapses under subsequent mining disturbances, rather than forming dangerous, large-area overhangs. The resulting fragmented rock blocks are relatively small in size and more rationally graded, more effectively filling goaf areas, with a high coefficient of fragmentation, creating ideal conditions for the formation of natural backfill or subsequent artificial backfill.

[0025] B. Tunneling: Tunneling forms a roadway 5 that serves the narrow working face 1.

[0026] C. Roof Cutting: During the mining process, directional hydraulic cutting 9 is implemented on the roof 4. This cutting process can adopt two timing modes to actively coordinate with the surrounding rock control: one is to implement it after the narrow working face 1 roadway is excavated and before the start of mining operations, i.e., "delayed excavation" roof cutting; the other is to pre-construct it at a certain distance ahead of the current mining position during the mining advance, i.e., "advanced mining" roof cutting. This measure aims to guide the directional fracture and stress transfer of the roof 5.

[0027] This process involves linear cutting based on the planar weakening formed by fracturing. It's like pre-setting a fracture guide line in the top plate 5. Its main functions are: 1. The forced fracture of the roof slab along the cut surface makes the collapse range, shape and step distance controllable and predictable, avoiding the impact danger caused by irregular collapse.

[0028] 2. By cutting off the stress transmission of key strata, the load of the overlying strata is actively transferred to the support area behind or on both sides of the goaf (such as coal face or backfill), thereby significantly reducing stress concentration near the working face and roadway and achieving pressure relief protection.

[0029] 3. In conjunction with hydraulic fracturing, while the roof 5 fractures at the predetermined position, the rocks near the fracture surface are further broken due to pre-existing fissures, enhancing the fragmentation effect of the collapse body.

[0030] In addition to the core technologies mentioned above, other proven and effective roof weakening technologies can be integrated or replaced in practice, such as: blasting pre-splitting, drilling decompression, chemical softening, etc.

[0031] D. Coal mining: Coal is mined from the narrow working face 1, and the resulting roof collapse rock naturally fills the goaf.

[0032] E. Grouting Treatment: First, the goaf is initially filled using the naturally collapsed rock from the roof 4 caused by mining. Then, based on the roof connection of the initial filling, it is decided whether to supplement the filling in the unconnected areas to construct the artificial filling support structure 3.

[0033] It is worth mentioning that the "supplementary filling" step E can be performed through directional long-hole grouting, which can be carried out in the L-shaped area on the ground or in a localized section of a straight hole; alternatively, backfilling with gangue can be used. During the grouting process, monitoring data on the development of overburden fissures and delamination can be used to dynamically guide the grouting operation. An "intermittent, segmented" grouting process can be adopted to inject grout into key strata in a targeted manner, optimizing material consumption while ensuring support effectiveness.

[0034] It is worth mentioning that the above methods are not limited to promoting roof collapse and fragmentation through various means such as hydraulic fracturing and roof cutting.

[0035] S4. After processing the goaf areas of the two narrow working faces 1 that have been mined in steps S2 and S3, the artificial backfill support structures 3 on both sides are formed. Subsequent steps should be carried out only after the artificial backfill support structures 3 have reached the predetermined strength.

[0036] S5. Under the lateral support of the artificial filling body support structure 3 on both sides, the wide working face 2 with a longer inclined length, located between the two narrow working faces 1, is finally excavated and mined, thereby completing the complete continuation of the wide working face 2.

[0037] In this context, each working face within the panel shares or is adjacent to a roadway 5, thereby ensuring that no permanent coal pillars are left within the panel, thus achieving continuous mining without coal pillars within the panel.

[0038] After the two narrow working faces 1 are mined and backfilled and consolidated as described above, the middle wide working face 2 is mined; and after the wide working face 2 is mined, it can also be backfilled considering economic benefits and practical conditions.

[0039] For extra-thick coal seams, this method can also employ the following two adaptive process schemes in addition to conventional processes: Option 1: In the narrow working face 1 with a shorter dip length, the top coal caving process will not be implemented; only the coal within the cutting height range of the coal mining machine will be recovered. After the narrow working face 1 is mined out, grouting materials will be used to fill and reinforce the goaf in a timely manner to form a stable support structure. Subsequently, in the wide working face 2 with a longer dip length, the top coal caving process will be implemented normally to fully recover the top coal.

[0040] Option 2: Based on the coal seam conditions, roof stability (4), and roadway support status (5), partial or full-thickness top coal caving can be implemented in the narrow working face (1). If full top coal caving is adopted, the filling intensity and amount of the subsequent goaf should be increased accordingly to ensure overburden stability. To further balance resource recovery and safety, the design width of the narrow working face (1) can be appropriately reduced according to the actual situation, thereby controlling the exposed area of ​​roof (4) and the degree of mine pressure manifestation within a limited range.

[0041] This method boasts exceptional applicability. Specifically, regarding coal seam thickness, it can adapt to thin, medium-thick, and extra-thick seams by adjusting core parameters. For instance, for extra-thick seams, strategies such as "narrow face mining with only bottom wall construction and wide face full-thickness longwall caving" or "dynamically adjusting the coal release volume and filling intensity in the narrow face" can be flexibly selected to maximize resource recovery while ensuring the stability of the support structure. In terms of mining technology, this method is not tied to any specific process and can be combined with various mainstream mining techniques such as layered mining, full-height mining in one pass, and longwall top coal caving. Its proactive control process of "fracturing first, cutting the roof, and then mining" can be embedded as a pre-module into various processes to optimize roof control. Furthermore, for different geological conditions (such as hard roof, weak roof, and high ground stress), targeted surrounding rock control can be achieved by adjusting fracturing parameters, the timing and location of cutting, and the material and construction method of the filling body.

[0042] Furthermore, to optimize the performance of the artificial infill support structure 3, a specially formulated infill material can be used. This material may contain compressible phase change materials, such as composite particles 6 having a brittle outer shell 7 and a compressible core 8. The composite particles 6 can be mixed into the matrix of the infill material at a dosage of 15% to 30% of the total volume of the infill material. This causes the infill to exhibit a phased mechanical response under pressure: in the first pressure stage, the brittle outer shell 7 of the composite particles 6 breaks and the compressible core 8 is compressed, leading to a large compressive deformation of the infill to achieve a tight top; in the second pressure stage, after reaching a predetermined compressive strain or pressure threshold, the composite particles 6 are compacted, and the matrix skeleton of the infill becomes the main load-bearing structure, with its compressive stiffness significantly improved to provide stable support.

[0043] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for pillarless collaborative mining of a panel, characterized in that, Includes the following steps: S1. Arrange at least three adjacent working faces in sequence along the direction within the panel area, and make the design width of the adjacent working faces alternate in the order of "wide working face, narrow working face, wide working face", among which the two working faces located on the outermost side of the entire panel area direction sequence are wide working faces. S2. Excavate and mine a narrow working face with a relatively short dip length on one side of the panel; S3. Skip an adjacent wide working face and excavate and mine another narrow working face with a shorter dip length on the other side of the panel; S4. Handling the goaf areas of the two narrow working faces that have been mined in steps S2 and S3: First, use the naturally collapsed roof rock caused by mining to fill the goaf area for the first time; then, depending on the roof connection of the first filling, decide whether to fill the non-roofed area to construct the artificial filling body support structure on both sides. S5. Under the lateral support of the artificial backfill support structure on both sides, the wide working face with a long dip length located between two narrow working faces is tunneled and mined. In steps S2 and S3, the tunneling and mining operations in the narrow working face both include the following process steps in sequence: A. Perform hydraulic fracturing in the roof above the mining area of ​​the narrow working face; B. The tunneling process forms a roadway system that serves the narrow working face; C. During the mining process, directional cutting is carried out on the roof; D. Coal is mined from the narrow working face, and the resulting roof collapse fills the goaf with rocks. E. Based on the situation of the roof collapse rock filling and connecting with the goaf, inject filling grout into the unconnected area to construct an artificial filling support structure.

2. The method for pillarless collaborative mining in a panel as described in claim 1, characterized in that: The hydraulic fracturing includes low-level fracturing performed on the roof of the roadway and high-level fracturing performed on the roof of the middle region of the working face.

3. The method for pillarless collaborative mining in a panel as described in claim 1, characterized in that, In step S4: After the artificial filling support structure constructed in the goaf of the two narrow working faces reaches the predetermined strength, step S5 is then executed.

4. The method for pillarless collaborative mining in a panel as described in claim 1, characterized in that: When the thickness of the coal seam in the panel area is greater than 8 meters, the mining of the narrow working face in steps S2 and S3 only involves mining the bottom of the coal seam, and then constructing a roof-mounted artificial backfill support structure; the mining of the wide working face in step S5 involves whole-seam mining including bottom mining and top caving.

5. The method for pillarless collaborative mining in a panel as described in any one of claims 1, characterized in that: Each working face within the panel shares or is adjacent to another roadway, and no permanent section coal pillars are left inside the panel.

6. The method for pillarless collaborative mining in a panel as described in any one of claims 1, characterized in that, In step S4: the filling material used to construct the artificial filling body support structure for the narrow working surface includes a compressible phase change material; The compressible phase change material is used to enable the artificial infill support structure to exhibit a phased mechanical response under pressure: in the first pressure stage, it provides a large compressive deformation capacity to achieve a tight connection with the top; after reaching a predetermined compressive strain or pressure threshold, it enters the second pressure stage, where its compressive stiffness is significantly improved to provide stable support.

7. The method for pillarless collaborative mining in a panel as described in claim 6, characterized in that: The compressible phase change material is a composite particle with a brittle outer shell and a compressible core. The composite particle is mixed in the matrix of the filling material at a dosage of 15% to 30% of the total volume of the filling material. In the first pressure stage, the brittle outer shell of the composite particle breaks and the compressible core is compressed, which leads to the compression deformation of the artificial filling support structure. In the second pressure stage, the composite particle is compacted, and the matrix skeleton of the artificial filling support structure becomes the main load-bearing body.

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