A strip-type backfill support structure for coal mine goaf

Abstract

This utility model pertains to an advanced support structure for goaf areas left by small coal mines in fully mechanized mining faces, specifically a strip-type filling support structure for goaf areas. It includes: a filling strip system comprising strip-shaped filling bodies arranged at intervals within the goaf, with a set width and height flush with the roof and floor of the goaf; the number and position of the filling strips are adjusted according to the goaf dip width: when the goaf width is ≤ a first threshold, no strips are arranged; when the goaf width is between the first and second thresholds, a single strip is arranged in the middle of the goaf; when the goaf width is ≥ the second threshold, at least two filling strips are symmetrically arranged; a collaborative support module, including a roof anchoring unit, a temporary support unit, and an auxiliary bearing body, used to simultaneously support the goaf; and an integrated ventilation module, including a forced-in ventilation device, used to ventilate the goaf. This invention can achieve stability of the goaf roof under advanced pressure.

Description

Technical Field

[0001] This utility model relates to an advanced support structure for the goaf left by small coal mines in fully mechanized mining faces, specifically a strip-type filling support structure for coal mine goaf. Background Technology

[0002] To meet the demands of social development, coal consumption has risen sharply. However, my country's coal reserves are finite. Against this backdrop, contemporary society has placed new demands on coal mining. Mining must optimize technology and processes, increase extraction rates, minimize or eliminate residual coal, and maximize the extraction and utilization of underground coal resources to reduce waste. Due to historical mining practices, Shanxi Province is dotted with small, scattered coal mines of varying sizes. Limited by early mining techniques, these small mines only mined coal with favorable deposit conditions, low pressure, and shallow burial depths, leaving behind a large amount of coal resources. Furthermore, these remaining high-quality coal deposits contain numerous mining roadways and open areas, known as empty roadways or old goafs. With the continuous depletion of coal resources, under the new circumstances, it is necessary to reorganize and consolidate small coal mines and re-extract the previously leftover coal resources.

[0003] Currently, coal mining methods in my country are primarily based on fully mechanized mining. However, fully mechanized mining places high demands on the geological conditions of the coal seams at the working face. Due to historical mining practices, the integrity of coal seams in integrated mines has been compromised, especially by old goaf areas left underground. These goaf areas, having been neglected for years, have complex surrounding rock structures. Under the combined effects of geostress and tectonic stress, the roof, floor, and sidewalls of these goaf areas undergo varying degrees of deformation and damage. Water may also be present in some areas, further exacerbating the difficulties of coal mining. The impact of old goaf areas on the longwall face recovery is mainly manifested in the following aspects:

[0004] (1) When the working face is pushed to this area, the original support of the old goaf is unable to withstand the advance support pressure of the working face, the roof of the goaf collapses, which can easily lead to problems such as roof fall and side collapse.

[0005] (2) When the working face passes through the old goaf, the control distance of the roof increases, and the roof is suspended over a large area. Under the action of mining stress, the working face will collapse and fall. At the same time, the pressure on the support will increase, which will cause the support to be unable to advance in time, seriously threatening the safe mining of the working face.

[0006] (3) If the basic roof above the old goaf breaks when the working face approaches, the rock block will rotate and become unstable. The working face will likely experience a large-scale roof collapse, causing safety accidents such as roof collapse, roof fall, and large-scale roof fall, making it difficult for the working face to pass through the goaf.

[0007] Crossing old goaf areas in fully mechanized mining has always been a technical challenge in coal mining. The existence of old goaf areas seriously threatens production safety during the mining process. Before mining, the surrounding rock of old goaf areas must be treated in advance to maintain the safety and stability of the mining face. Summary of the Invention

[0008] To solve the above problems, this utility model provides a strip-type filling support structure for coal mine goaf.

[0009] This utility model adopts the following technical solution: a strip-type filling support structure for coal mine goaf, comprising:

[0010] The filling strip system includes strip-shaped filling bodies arranged at intervals in the goaf, with the width of the filling body being a set value and the height being flush with the top and bottom plates of the goaf.

[0011] Adjust the number and location of filling strips according to the dip width of the goaf:

[0012] When the width of the goaf is less than or equal to the first threshold, no strips are arranged;

[0013] When the width of the goaf is between the first threshold and the second threshold, a single strip is placed in the middle of the goaf.

[0014] When the width of the goaf is greater than or equal to the second threshold, at least two filling strips shall be arranged symmetrically.

[0015] The collaborative support module includes a roof anchoring unit, a temporary support unit, and an auxiliary bearing body, which are used to simultaneously support the goaf.

[0016] An integrated ventilation module, including a forced ventilation device, is used to ventilate the goaf.

[0017] In some embodiments, the filling strip system is constructed using a high-water material with a water-cement ratio ranging from 1.5:1 to 2.5:1, a 7-day uniaxial compressive strength ≥5 MPa, and a residual strength ≥60% at 10% of peak strain.

[0018] In some embodiments, the first threshold is 5–10m, and the second threshold is 15–25m;

[0019] The symmetrically arranged filling strips are spaced 5–10m apart, and the strip width is 2–4m.

[0020] In some embodiments, the collaborative support module includes:

[0021] Roof anchoring unit: includes a group of threaded steel anchor bolts, a group of prestressed anchor cables, and a metal mesh. The group of threaded steel anchor bolts and the group of prestressed anchor cables are installed on the roof of the goaf, and the metal mesh is installed below the roof.

[0022] The temporary support unit consists of an array of multiple hydraulic props, which are supported between the roof and floor of the goaf.

[0023] Auxiliary load-bearing structures, including timber stacks or concrete piers, are arranged in the stress concentration zone of the roof of the goaf.

[0024] In some embodiments, temporary support units are replaced with steel-framed canopy structures in the fractured roof area of ​​the goaf.

[0025] In some embodiments, the filling strip system incorporates a reinforcing skeleton, including:

[0026] Tie rods are installed in the strip-shaped filling body and are made of resin or glass fiber, with the length matching the width of the strip-shaped filling body.

[0027] The restraint netting, made of high-strength plastic mesh or welded steel mesh, covers the surface of the strip-shaped filling body.

[0028] In some embodiments, the spacing between tie rods is 500–1000 mm.

[0029] In some embodiments, an intelligent monitoring system is also included, comprising:

[0030] Pressure sensors are installed on the surface of the hydraulic support and the filling body;

[0031] The deformation monitoring unit uses a laser rangefinder or a top plate delamination meter.

[0032] The data processor receives data from the pressure sensor and deformation monitoring unit, and generates a pressure distribution cloud map and a top plate displacement curve.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This utility model proposes a form of advanced support for coal mine goaf, drawing on the principle of strip backfill mining. It fully utilizes the supporting capacity of the thick, hard limestone layers at the working face, taking advantage of the goaf's characteristics of a long strike perpendicular to the working face and a relatively short dip. It employs high-water backfill strips to support key parts of the goaf roof, combined with anchor mesh cable reinforcement of the roof and temporary support from individual columns, achieving stability of the goaf roof under advanced pressure. Furthermore, it significantly reduces material costs, allows for rapid construction with a short construction period, uses less material, and has minimal impact on the mine's transportation system. Additionally, the large wall width greatly improves wall stability, facilitating stress on the support structure. Attached Figure Description

[0035] Figure 1 This is a layout diagram of the present utility model;

[0036] Figure 2 for Figure 1 Top view;

[0037] Figure 3 Schematic diagram of the installation of auxiliary load-bearing structure in the stress concentration zone of the top slab;

[0038] Figure 4 A schematic diagram of the built-in reinforcing skeleton for the filling strip system;

[0039] In the figure, 1-strip filling body, 2-hydraulic support, 3-prestressed anchor cable group, 4-threaded steel anchor bolt group, 5-auxiliary bearing body, 6-restraint net, 7-pull anchor bolt. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0041] like Figure 1 , 2 As shown, a strip-type backfill support structure for coal mine goaf includes:

[0042] Backfill strip system: Strip-shaped backfill bodies 1 are arranged at intervals in the goaf area. The width of the backfill body is a set value, and the height is flush with the top and bottom plates of the goaf area.

[0043] Adjust the number and position of filling strips according to the width of the void:

[0044] When the width of the empty area is less than or equal to the first threshold, no strips are placed;

[0045] When the width of the empty area is between the first threshold and the second threshold, a single strip is placed in the middle of the empty area;

[0046] When the width of the empty area is greater than or equal to the second threshold, at least two filling strips shall be arranged symmetrically.

[0047] Collaborative support module: includes roof anchoring unit, temporary support unit and auxiliary bearing body, used to support the goaf at the same time;

[0048] Integrated ventilation module: includes a forced ventilation device for ventilating the goaf area, with the end of the ventilation duct ≤10m from the working face.

[0049] In a specific embodiment, the filling strip system is constructed using a high-water-content material with a water-cement ratio ranging from 1.5:1 to 2.5:1, a 7-day uniaxial compressive strength ≥5MPa, and a residual strength ≥60% at 10% peak strain.

[0050] The high-water-content material consists of two components, A and B. Components A and B, when mixed separately with water, do not solidify for 24 hours, creating conditions to avoid pipe blockage and, under certain conditions, eliminate the need for pipe flushing. However, once the A and B slurries are mixed, they harden rapidly. While components A and B do not solidify for an extended period after being stirred separately with water, they begin to set within 20 minutes when mixed. Under standard laboratory testing conditions, with a water-cement ratio of 1.5:1, the initial setting time can be controlled within 15 minutes. The compressive strength reaches 2.1 MPa at 2 hours, 5.6 MPa at 24 hours, 10.36 MPa at 7 days, and 10.82 MPa at 28 days. The 1-day strength reaches over 50% of the final strength, and the 7-day strength reaches over 90% of the final strength.

[0051] In a specific embodiment, the first threshold is 5–10m, and the second threshold is 15–25m; the symmetrically arranged filling strips are spaced 5–10m apart, and the strip width is 2–4m. The filling strips are filled with high-water-content materials, and the filling strips are formed and laterally restrained using flexible templates, resin tie bolts, and high-strength double-resistance plastic mesh. In this embodiment, the width of the filling strip is 3m, and the spacing between the filling strips is 8m.

[0052] The filling strip system has a built-in reinforcing skeleton, including: tie rods 7: made of resin or fiberglass, with a length matching the width of the filling body; and restraint mesh 6: a high-strength plastic mesh or welded steel mesh covering the surface of the filling body. The spacing between the tie rod groups 7 is 500–1000 mm.

[0053] Specifically, such as Figure 3 As shown, the collaborative support module includes:

[0054] Top slab anchoring unit: includes threaded steel anchor bolt group 4, prestressed anchor cable group 3 and metal protective net. Threaded steel anchor bolt group 4 and prestressed anchor cable group 3 are driven into the top slab, and a metal protective net is installed under the top slab. The spacing between anchor bolts is 800–1200 mm, and the spacing between anchor cables is 1500–2500 mm.

[0055] Temporary support unit: consists of two arrays of hydraulic props with a row spacing of 1000–1500 mm; in the fractured area of ​​the roof, the temporary support unit is replaced by a steel shed structure with a span of 3–5 m.

[0056] Auxiliary load-bearing structure 5: including timber stacks or concrete piers, arranged in the stress concentration area of ​​the top slab.

[0057] It also includes an intelligent monitoring system, including: pressure sensors: deployed on the surface of the hydraulic support and the filling body;

[0058] Deformation monitoring unit: uses a laser rangefinder or a top plate delamination meter; Data processor: the data processor receives data from the pressure sensor and the deformation monitoring unit, and generates a pressure distribution cloud map and a top plate displacement curve.

[0059] In a specific embodiment, the intelligent monitoring system constructs a dynamic monitoring system covering the entire working face by deploying a network of pressure sensors on the surfaces of hydraulic supports and filling bodies, and simultaneously deploying laser rangefinders and roof delamination meters in key areas. A set of pressure sensors is installed for every 10 hydraulic supports, collecting hydraulic pressure data from 0-40 MPa in real time; a laser rangefinder is deployed every 20 meters along the centerline of the roadway roof to capture roof subsidence; and the roof delamination meters are densified to a 10-meter spacing in the fractured areas. All sensors aggregate data to an industrial-grade data processor via an intrinsically safe mining data substation.

[0060] The data processor uses a bilinear interpolation algorithm to convert discrete pressure values ​​into a two-dimensional pressure cloud map, which is then displayed visually in pseudo-color rendering (blue < 5MPa safe zone, yellow 5-10MPa warning zone, red > 10MPa danger zone). Simultaneously, it generates a roof displacement curve in real time, triggering an early warning when the daily displacement exceeds 5 mm or the displacement acceleration exceeds 0.1 mm / s². The system has a three-level response mechanism: an audible and visual alarm is activated when the local pressure exceeds 8MPa; the micro-expansion agent dosage is automatically increased to 0.8% when the pressure remains above 10MPa for 30 minutes; and the equipment power is cut off and the backup ventilation system is activated when the roof delamination exceeds 50 mm.

[0061] The specific construction process includes:

[0062] 1. Use a laser rangefinder to measure the width of the void. When the width is ≤8m, the self-supporting capacity of the top plate is deemed sufficient, and filling is not required. When the width is between 8-20m, mark the central axis of the void. When the width is ≥20m, set positioning reference lines at 1 / 3 and 2 / 3 of the width.

[0063] The integrity of the roof was verified by drilling and sampling, and additional roof delamination monitoring points were added in the fractured area.

[0064] 2. Positioning and shaping of strip-shaped filling material 1:

[0065] Positioning reference: Infrared reference lines are set every 30m along the airspace;

[0066] Formwork installation: For open areas with a width of 8-20m: 60mm thick wooden board baffles are installed along the central axis; For open areas with a width >20m: baffles are installed in parallel at 1 / 3 and 2 / 3 of the width; The outside of the baffles is reinforced with hydraulic supports (column spacing 1200mm).

[0067] 3. High-water-content material grouting:

[0068] Material ratio: Mix component A: component B = 1:1, water-cement ratio 1.8:1;

[0069] High-water-cement ratio cement is a special type of cement that can set rapidly under high water-cement ratio conditions. It is also an inorganic filler material that can set rapidly under high water-cement ratio conditions. The material itself and related technologies are well-established and widely used.

[0070] The high-water-content material consists of two components, A and B. Components A and B, when mixed separately with water, do not solidify for 24 hours, creating conditions to avoid pipeline blockage and, under certain conditions, eliminate the need for pipeline flushing. However, once the two components are mixed, they harden rapidly. While components A and B do not solidify for an extended period after being stirred separately with water, they begin to set within 20 minutes when mixed. The uniaxial compressive strength of the high-water-content material is inversely proportional to the water-cement ratio. A lower water-cement ratio requires less water, resulting in higher set strength and requiring more high-water-content material per unit volume for filling. Conversely, a higher water-cement ratio requires more water, resulting in lower set strength and requiring less high-water-content material per unit volume for filling.

[0071] 4. Construction of the collaborative support system:

[0072] Top slab anchoring unit:

[0073] The anchor material for the threaded steel anchor group is left-hand threaded steel, MSGLW-400, with top and side anchors measuring Ф20×2400mm. The anchor arrangement is as follows: top anchors are drilled to a depth of 2300mm, with 100mm exposed, spaced 1000mm apart, and arranged in rows of 1000mm, with 6 anchors per row, inclined at approximately 20° to both sides. Anchoring agents include one each of CK2335 and K2360, with CK2335 installed first and K2360 installed later. The design anchoring force is 125kN, and the pre-tightening torque is 250N-m.

[0074] The prestressed anchor cable group is arranged on the roof slab 500mm from the sidewall of the opening, with a spacing of 2000mm. The locking anchor cable needs to extend 500mm beyond the opening position on both sides. Locking anchor cables are added before the roadway opening and breakthrough, with a spacing of 1500mm to 2000mm, based on the centerline of the roadway; when the distance from the sidewall is less than 1000mm, no additional anchor cable support is required.

[0075] Temporary support system:

[0076] The individual column array uses DW45-250 / 110X type hydraulic props, with a row spacing of 1200×1200mm. The crushed roof area is replaced with mining H-beam scaffolding.

[0077] This strip-filled support structure for the goaf in a coal mine achieves a triple breakthrough in roof stability, construction economy, and safety through the dynamic arrangement of high-water-content filling strips in conjunction with collaborative support modules. In its application at the 15206 working face of Shouyang Coal Mine, the filling strips reduced the effective span of the goaf roof from the critical failure value of 15.71m to ≤8m, completely eliminating the risk of roof collapse caused by pre-support pressure. The plastic deformation characteristics of the high-water-content material enable the support structure to have self-adaptive pressure-bearing capacity, maintaining stable load-bearing capacity even under mining-induced stress fluctuations, and improving the deformation resistance of traditional concrete filling structures by 2 times.

[0078] In terms of economic benefits, strip filling reduced material consumption from 6,177 tons for full filling to 792 tons, and material costs from 9.88 million yuan to 1.26 million yuan, while shortening the construction period by 50%. This optimization stems from precise strip parameter design and the rapid setting characteristics of high-water-content materials, enabling a daily filling progress of 3.2 meters. The anchor-mesh cable system in the collaborative support module forms a three-level protection with the single-column array: the anchor bolt group controls local delamination, the hydraulic props provide advanced support, and the timber stack structure assists in dispersing the load.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A strip-type filling support structure for coal mine goaf, characterized in that, include: The filling strip system includes strip-shaped filling bodies arranged at intervals in the goaf, with the width of the filling body being a set value and the height being flush with the top and bottom plates of the goaf. Adjust the number and location of filling strips according to the dip width of the goaf: When the width of the goaf is less than or equal to the first threshold, no strips are arranged; When the width of the goaf is between the first threshold and the second threshold, a single strip is placed in the middle of the goaf. When the width of the goaf is greater than or equal to the second threshold, at least two filling strips shall be arranged symmetrically. The collaborative support module includes a roof anchoring unit, a temporary support unit, and an auxiliary bearing body, which are used to simultaneously support the goaf. An integrated ventilation module, including a forced ventilation device, is used to ventilate the goaf.

2. The strip-type backfill support structure for coal mine goaf according to claim 1, characterized in that: The filling strip system is constructed with high-water-content materials, with a 7-day uniaxial compressive strength ≥5MPa and a residual strength ≥60% at 10% peak strain.

3. The strip-type filling support structure for coal mine goaf according to claim 1, characterized in that: The first threshold is 5–10m, and the second threshold is 15–25m; The symmetrically arranged filling strips are spaced 5–10m apart, and the strip width is 2–4m.

4. The strip-type backfill support structure for coal mine goaf according to claim 1, characterized in that: The collaborative support module includes: Roof anchoring unit: includes a group of threaded steel anchor bolts, a group of prestressed anchor cables, and a metal mesh. The group of threaded steel anchor bolts and the group of prestressed anchor cables are installed on the roof of the goaf, and the metal mesh is installed below the roof. The temporary support unit consists of an array of multiple hydraulic props, which are supported between the roof and floor of the goaf. Auxiliary load-bearing structures, including timber stacks or concrete piers, are arranged in the stress concentration zone of the roof of the goaf.

5. The strip-type backfill support structure for coal mine goaf according to claim 4, characterized in that: The temporary support unit was replaced with a steel-framed canopy structure in the fractured area of ​​the goaf roof.

6. The strip-type backfill support structure for coal mine goaf according to claim 1, characterized in that: The filling strip system has a built-in reinforcing skeleton, including: Tie rods are installed in the strip-shaped filling body and are made of resin or glass fiber, with the length matching the width of the strip-shaped filling body. The restraint netting, made of high-strength plastic mesh or welded steel mesh, covers the surface of the strip-shaped filling body.

7. The strip-type filling support structure for coal mine goaf according to claim 6, characterized in that: The spacing between the tie rods is 500–1000 mm.

8. The strip-type backfill support structure for coal mine goaf according to claim 1, characterized in that: It also includes intelligent monitoring systems, including: Pressure sensors are installed on the surface of the hydraulic support and the filling body; The deformation monitoring unit uses a laser rangefinder or a top plate delamination meter. The data processor receives data from the pressure sensor and deformation monitoring unit, and generates a pressure distribution cloud map and a top plate displacement curve.

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