A method for setting a mine safety isolation layer

Abstract

This application discloses a method for setting up a safety isolation layer in a mine, relating to the field of underground engineering technology in mining. The method includes: delineating the mining area; conducting downward layered mining within the mining area; using a pre-determined thickness area at the top of the mining area as a static isolation layer, and identifying and treating historical goaf areas and water-conducting faults within the static isolation layer; and within each layer, setting up temporary isolation layers around the ore body, and identifying and treating historical goaf areas and water-conducting faults within the temporary isolation layers. The mine safety isolation layer method provided by this application can effectively isolate the mining area and significantly reduce safety risks, effectively preventing potential safety hazards induced by historical goaf areas in the mine, and features safety, stability, controllable risks, and effective prevention.

Description

Technical Field

[0001] This application relates to the field of underground engineering technology in mining, and in particular to a method for setting up a safety isolation layer in a mine. Background Technology

[0002] The exploitation of underground mineral resources has a long history. As mining activities have continued to deepen, a large number of historical mining voids with large areas of cavities have been formed.

[0003] Due to limitations such as outdated early mining technologies, lack of archival data, and insufficient dynamic monitoring, many regions face the challenge of accurately tracing the spatial information of historical mining subsidence areas, defining their distribution range, and determining their spatial dimensions. This incompleteness of information means that mining subsidence areas remain hidden deep within mines, making them difficult to detect and effectively manage in a timely manner.

[0004] The existence of historical mining subsidence areas not only easily induces secondary disasters such as ground subsidence and foundation settlement, directly threatening the safety of people and the operational stability of infrastructure, but also imposes long-term constraints on the development and utilization of underground space resources. Mining subsidence areas may lead to tunnel deformation, collapse, and large-scale rock mass instability, increasing the risks of mining production activities. Summary of the Invention

[0005] In view of this, this application provides a method for setting up a mine safety isolation layer, which aims to solve one of the technical problems in the prior art.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a method for setting up a mine safety isolation layer, including: The mining area of ​​the mine is delineated, and the mining area is then mined in a downward stratified manner. The area located above the mining area with a predetermined thickness is used as a static isolation layer, and the historical goaf and water-conducting faults within the static isolation layer are identified and treated. Within each layer, temporary isolation layers are set around the ore body to be mined, and historical goaf areas and water-conducting faults within the temporary isolation layers are explored and treated.

[0007] In an optional implementation, the static isolation layer is a layered, dense solid with thickness arranged horizontally, and its thickness is calculated as follows: ; Where H is the thickness of the static isolation layer; α is an empirical correction coefficient, with a value ranging from 0.8 to 1.5; The maximum expected impact stress; For safety margin, the value ranges from 1.5 to 2.0; The density of the static isolation layer material is given; g is the acceleration due to gravity. The internal friction angle of the material constituting the static isolation layer.

[0008] In an optional embodiment, the static isolation layer consists of surrounding rock and ore body, and the static isolation layer also includes at least one of cemented backfill goaf and cemented backfill goaf of domestically mined tailings.

[0009] In an optional implementation, a temporary isolation layer is set around the ore body to be mined, and the temporary isolation layer is an area no more than 10m to 50m away from the ore body in the horizontal direction; And / or, the upper part of the temporary isolation layer is an upper developed horizontal tunnel or the upper surrounding rock, and the lower part of the temporary isolation layer is a lower developed horizontal tunnel or the lower surrounding rock.

[0010] In an optional implementation, after the ore body in a certain layer is fully mined, the goaf is cemented and filled, and the historical goaf and water-conducting faults in the layer are explored and treated, so that the layer and the previous layer or static isolation layer are combined to form a new static isolation layer.

[0011] In optional implementations, historical goaf areas include constructed shafts, developed horizontal tunnels, developed ramps, private mining shafts, private mining adits, private mining blind shafts, private mining developed horizontal tunnels, completed private mining waterlogged goaf areas, private mining waste rock filled goaf areas, private mining tailings cemented filled goaf areas, and private mining unfilled goaf areas.

[0012] In an optional implementation, the safety of the static isolation layer and the temporary isolation layer is investigated, and the investigation methods include at least one of field investigation, engineering drilling, engineering geophysical exploration, theoretical analysis, laboratory testing and numerical simulation.

[0013] In an optional implementation, the treatment method includes: reinforcing the surrounding rock with a support system, wherein the support and reinforcement measures include at least one of anchor bolt support, anchor mesh support, anchor cable support, and shotcrete support.

[0014] In an optional implementation, the treatment method further includes: setting up a goaf sealing wall and drainage holes in the historical goaf area, with the goaf sealing wall arranged in the roadway area of ​​the surrounding rock and the drainage holes arranged at the bottom of the goaf sealing wall. The treatment methods also include: setting up drainage ditches and drainage systems within the static isolation layer and the temporary isolation layer.

[0015] In optional implementations, the remediation method further includes: cementing and backfilling the waterlogged goaf areas and unfilled goaf areas of the fully mined private mines; conducting seismic sand liquefaction risk assessments on the goaf areas filled with waste rock and the goaf areas cemented and backfilled with tailings from the private mines; and reinforcing the goaf areas if the assessment results do not meet safety standards.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: This application proposes a method for setting up a mine safety isolation layer, including delineating the mining area of ​​the mine, carrying out downward layered mining of the mining area; using the area located above the mining area with a predetermined thickness as a static isolation layer, and identifying and treating the historical goaf and water-conducting fault within the static isolation layer; setting the static isolation layer as the top layer of the mining area, and identifying and treating the historical goaf and water-conducting fault within the top layer, thereby preventing external safety risks that may be caused by the surface, water-conducting faults, and historical goaf, and providing safety assurance for the mining operation area of ​​the mine; Within each stratum, temporary isolation layers are set up around the perimeter of the body to be oreed. Historical goafs and water-conducting faults within these temporary isolation layers are identified and treated. Even with a static isolation layer at the top of the mining area, temporary isolation layers are also set up around each body to be oreed, and historical goafs and water-conducting faults within these temporary isolation layers are identified and treated. This effectively isolates the top and perimeter of each body to be oreed from historical goafs and water-conducting faults, ensuring its own safety and effectively preventing safety risks associated with mining in the upper and deeper areas during the mining process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The flowcharts of the method for setting up a mine safety isolation layer in some embodiments of this application are shown; Figure 2 A schematic diagram of the structure of the mine safety isolation layer in some embodiments of this application is shown.

[0019] Key component symbols: 1-Constructed vertical shaft; 2-Developed horizontal tunnel; 21-First-level horizontal tunnel; 3-Horizontal tunnel to be developed; 4-Developed inclined ramp; 5-Inclined inclined ramp to be developed; 6-Mining vertical shaft; 7-Mining adit; 8-Mining blind vertical shaft; 9-Developed horizontal tunnel in mining; 10-Mining body to be ored; 11-Water-conducting fault; 1201-Waterlogged goaf in mining; 1202-Waste rock-filled goaf in mining; 1203-Cemented tailings-filled goaf in mining; 1204-Unfilled goaf in mining; 1301-Cemented-filled goaf; 14-Vein roadway; 1501-Static isolation layer; 1502-Temporary isolation layer; 16-Surface; 17-Surrounding rock. Detailed Implementation

[0020] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] The high degree of concealment and uncertainty of underground engineering information means that historical mining subsidence areas lie hidden deep within mines. This not only easily induces secondary disasters such as ground subsidence and foundation settlement, directly threatening the safety of people and the stability of infrastructure operation, but also imposes long-term constraints on the development and utilization of underground space resources, increasing the hidden dangers of roadway deformation, collapse, and large-scale rock mass instability, thus posing huge risks and challenges.

[0026] In response to the above problems, such as Figure 1 As shown, the embodiments of this application provide a method for setting up a mine safety isolation layer, which is mainly used to explore and manage the historical goaf and water-conducting fault 11 in the top of the mining area and the surrounding area of ​​the ore body 10 in the mine, so as to achieve overall effective isolation of the historical goaf in the mining area and significantly reduce the safety risks of the mining operation area.

[0027] Methods for setting up safety isolation layers in mines include: Step S10: Delineate the mining area of ​​the mine and carry out downward stratified mining in the mining area.

[0028] After delineating the mining area, the mine construction forms vertical shafts, level tunnels, and ramps. The ramps include ramp 5 to be developed and ramp 4 already developed. Ramp 5 to be developed is a gently sloping passage that has not yet been constructed and is planned to be excavated.

[0029] Based on geological survey data, select an appropriate excavation method (such as drill and blast or mechanical method) to excavate the shaft.

[0030] First, the top of the shaft is excavated to form the first level roadway 21, and the surrounding rock 17 on the side of the roadway is supported in time. Then, it is gradually expanded downward to form a multi-level roadway, that is, the level roadway 3 to be developed is excavated. The level roadway 3 to be developed refers to the horizontal roadway within the mine planning area that has not yet been excavated.

[0031] Step S20: The area located above the mining area with a preset thickness is designated as a static isolation layer 1501, and the historical goaf and water-conducting fault 11 within the static isolation layer 1501 are investigated and treated.

[0032] In one embodiment, such as Figure 2 As shown, the static isolation layer 1501 is located above the first level lane 21.

[0033] The mining area employs a downward-layered mining method. In related technologies, the design method for the top layer of downward-layered mining generally involves determining the thickness of the top layer based on geological conditions and ore body characteristics. Generally, the top layer thickness should be sufficiently large to ensure adequate load-bearing capacity and prevent collapse. Simultaneously, suitable support schemes are designed, such as anchor bolts, anchor cables, metal mesh, and shotcrete, to enhance the stability of the roof. Analysis has revealed two major safety hazards in the current mining area: firstly, the historical goaf area at the top layer has not been systematically explored and treated; secondly, the water-conducting fault 11 has not been effectively treated. These unexplored and untreated geological structures seriously threaten the safe production of the mine and may trigger major safety accidents such as water inrush and roof collapse.

[0034] This application sets a static isolation layer 1501 as the top layer of the mining area, and explores and manages the historical goaf and water-conducting fault 11 within the top layer to prevent external safety risks that may be caused by the surface 16, water-conducting fault 11, and historical goaf, and to provide safety guarantees for the mining operation area.

[0035] In step S30, a temporary isolation layer 1502 is set around the ore body 10 in each layer, and the historical goaf and water-conducting fault 11 within the temporary isolation layer 1502 are explored and treated.

[0036] like Figure 2 As shown, below the first level tunnel 21 and the second level tunnel, there are multiple ore bodies 10 to be mined. (According to...) Figure 2 The ore body 10 within a layer is mined sequentially from left to right. For example, in the layer below the first level tunnel 21, after the leftmost ore body is mined, it is backfilled. After backfilling is completed, the ore body on the right is mined.

[0037] With a static isolation layer 1501 installed at the top of the mining area, a temporary isolation layer 1502 is also installed around each ore body 10 to be mined, and the historical goaf and water-conducting fault 11 within the temporary isolation layer 1502 are identified and treated. This effectively isolates the top and surrounding areas of each ore body 10 from the historical goaf and water-conducting fault 11, ensuring its own safety and effectively preventing safety risks from upper and deeper mining during the mining process.

[0038] In some embodiments, the static isolation layer 1501 is a layered dense solid arranged horizontally and having a thickness, the thickness of which is calculated using the following formula: ; Where H is the thickness of the static isolation layer 1501; α is an empirical correction coefficient, with a value ranging from 0.8 to 1.5; The maximum expected impact stress; For safety margin, the value ranges from 1.5 to 2.0; ρ is the density of the static isolation layer 1501 material; g is the acceleration due to gravity. The internal friction angle of the static isolation layer 1501 material.

[0039] The thickness of the static isolation layer 1501 obtained by the calculation formula enables the static isolation layer 1501 to have good impact resistance and stability, and can also reduce the workload of exploration and remediation.

[0040] Please continue reading. Figure 2 Above the first level tunnel 21 is a static isolation layer 1501. Once the thickness of the static isolation layer 1501 is determined, the historical mining area and water-conducting fault 11 above the static isolation layer 1501 no longer need to be explored and treated, reducing the workload of exploration and treatment.

[0041] The static isolation layer 1501 has good performance in preventing the risk of air shock waves caused by the instantaneous one-time collapse of the roof of the upper historical goaf area.

[0042] Specifically, the air resistance F during the rockfall process is calculated as follows:

[0043] In the formula, C is the frictional resistance coefficient; ρ is the air density, g / m³; and v is the velocity of the falling body during free fall, m / s. h is the height difference between the top and bottom plates of the empty area, m; A is the horizontal projected area of ​​the falling body, m2; S is the area of ​​the empty area, m2.

[0044] The total energy W gained by the air as it falls through the rock is calculated as follows:

[0045] The energy E gained by the airflow overcoming inertia as it moves along channel 14 is calculated as follows:

[0046] In the formula: t is the time it takes for the air to increase from a static state to its maximum value, in seconds; L is the distance the air travels in a channel with cross-section S, in meters; v is the air velocity, in meters per second.

[0047] Calculations show that the maximum airflow velocity generated when the static isolation layer 1501 withstands a single collapse of the roof slab is: .

[0048] Among them, v max The maximum airflow velocity (m / s) that the static isolation layer 1501 can withstand; C is the frictional resistance coefficient; A is the horizontal projected area (m²) of the falling body.2 h is the height difference between the top and bottom plates of the empty area, in meters; L is the assumed airflow distance within the cross-sectional channel, in meters; S is the area of ​​the empty area, in square meters. 2 .

[0049] In some embodiments, the static isolation layer 1501 is composed of surrounding rock 17 and ore body, and the static isolation layer 1501 is also composed of at least one of cemented backfill goaf 1301 and cemented backfill goaf 1203 of tailings from mining.

[0050] like Figure 2 As shown, the static isolation layer 1501 is a layered, dense solid with thickness arranged horizontally and maintaining spatial continuity. Among them, the surrounding rock 17, as the main part of the static isolation layer 1501, is located around the ore body 10, the cemented backfill goaf 1301, and the cemented backfill goaf 1203 of the domestic mining tailings, to form the main structure of the static isolation layer 1501.

[0051] The static isolation layer 1501 is constructed using a layered, dense solid structure that is continuously distributed in space and has a thickness. This structure ensures the overall stability of the static isolation layer 1501 while effectively blocking various external safety risks caused by factors such as goaf collapse and water inrush during the mining process of the ore body 10. It provides a reliable safety barrier for underground workers and equipment, significantly reduces the risk of safety accidents, and ensures the safe operation of the mine.

[0052] In some embodiments, a temporary isolation layer 1502 is provided around the ore body 10 to be mined, and the temporary isolation layer 1502 is a region located at a distance of no more than 10m to 50m from the ore body 10 in the horizontal direction.

[0053] The temporary isolation layer 1502 is a structure surrounding the area of ​​the ore body 10 to be mined. To improve the safety of mining operations, it eliminates potential safety hazards within a distance of no more than 10m to 50m surrounding the ore body 10.

[0054] The temporary isolation layer 1502 can be any value between 10m and 50m, used to proactively control the core area and risk concentration zone affected by mining. Implementing this measure enables proactive management of safety risks, precise and efficient engineering investment, and controllable and predictable mining processes. It is a key technical measure to ensure the safe and efficient operation of mining under complex conditions. The range is determined comprehensively based on rock mass mechanical behavior, geological risk distribution, technical detection capabilities, safety standards, and the principle of economic optimization. In practical applications, the value of the temporary isolation layer 1502 is dynamically evaluated and optimized based on mine geological conditions, mining technical parameters, and real-time monitoring feedback.

[0055] Among them, stress relief and stress buffering are crucial because mining activities disrupt the stress balance of the original rock, creating stress concentration zones (such as support pressure zones) around the stope. The temporary isolation layer 1502, ranging from 10m to 50m, forms a sufficiently thick "buffer layer" or "stress relief ring" to prevent high stress from directly acting on the ore body 10 or key roadways, thereby reducing the risk of dynamic disasters such as rock bursts and spalling.

[0056] The scope of hazard detection and mitigation covers the area adjacent to the mining site that is most likely to contain geological discontinuities or potential hazards that directly threaten mining safety, such as concealed faults, fractured zones, weak interlayers, old workings, and water-bearing structures. It also covers the effective range where current engineering geophysical exploration technologies (such as microseismic monitoring and ground-penetrating radar) can relatively accurately detect precursory signals of mining activities. Systematic investigation and mitigation within this area can directly eliminate near-field safety hazards.

[0057] Safety regulations, both domestically and internationally, typically specify clear guidelines and requirements for safe working distances around the stope, the size of safety pillars, and the length of advance supports. The 10m-50m range references and incorporates these guidelines, with adjustments made to suit specific ore body thickness, dip angle, and surrounding rock stability.

[0058] Effective and precise exploration and management of the temporary isolation layer 1502 area can effectively delineate the safe mining area from the goaf area with unclear goaf status, which helps to accurately control the ore mining range, reduce ore losses caused by goaf impacts, and improve the ore mining environment and recovery rate.

[0059] In some embodiments, the upper layer of the temporary isolation layer 1502 is the upper developed horizontal tunnel 2 or the upper surrounding rock 17, and the lower layer of the temporary isolation layer 1502 is the lower developed horizontal tunnel 2 or the lower surrounding rock 17. In other words, the temporary isolation layer 1502 will not affect or hinder the setting of the upper or lower developed horizontal tunnel 2, and plays a certain supporting and protective role.

[0060] In some embodiments, after the ore body in a certain layer is fully mined, the goaf is cemented and filled, and the historical goaf and water-conducting fault 11 in the layer are explored and treated, so that the layer and the previous layer or the static isolation layer 1501 are combined to form a new static isolation layer 1501.

[0061] For example, please refer to the following: Figure 2 After the ore body below the first level tunnel 21 is fully mined, the goaf is cemented and filled, and the historical goaf and water-conducting fault 11 within the layer are explored and treated, so that the layer and the static isolation layer 1501 are combined to form a new static isolation layer 1501.

[0062] Please refer to the following: Figure 2 After the ore body below the second level tunnel is fully mined, the goaf is cemented and filled, and the historical goaf and water-conducting fault 11 within the layer are explored and treated, so that the layer, the previous layer and the static isolation layer 1501 are combined to form a new static isolation layer 1501.

[0063] In some embodiments, such as Figure 2 As shown, the historical goaf areas include the constructed vertical shaft 1, the developed horizontal tunnel 2, the developed inclined roadway 4, the private mining vertical shaft 6, the private mining adit 7, the private mining blind vertical shaft 8, the private mining developed horizontal tunnel 9, the completed private mining waterlogged goaf area 1201, the private mining waste rock filled goaf area 1202, the private mining tailings cemented filled goaf area 1203, and the private mining unfilled goaf area 1204.

[0064] In some embodiments, the safety of the static isolation layer 1501 and the temporary isolation layer 1502 is investigated. The investigation methods include at least one of field investigation, engineering drilling, engineering geophysical exploration, theoretical analysis, indoor test and numerical simulation, so as to improve the safety status and overall stability of the surrounding rock 17, the ore body 10 and the filling goaf in the static isolation layer 1501 and the temporary isolation layer 1502, and give full play to the effective role of safety isolation.

[0065] The process includes: Field investigation: investigating geological structure, damage to surrounding rock 17, development of structural planes, hydrogeological conditions, support conditions, and support damage. Engineering drilling: deploying exploration boreholes in key areas (such as geologically complex zones, stress anomaly zones, and design isolation layer boundaries) for core logging and in-situ testing (using borehole television, sonic logging, and borehole radar to visually reveal the borehole wall rock mass structure, fracture development, and concealed structures), revealing rock mass integrity and hydrological conditions. Engineering geophysical exploration: using high-density electrical / electromagnetic methods and microseismic monitoring to monitor the isolation layer, creating spatial imaging maps of the rock mass / geological structure, revealing rock mass integrity, the location and scale of potential water-rich areas or cavities, and effectively exploring the isolation layer. Theoretical analysis: comprehensively evaluating rock mass quality by integrating all data from field investigation, drilling, geophysical exploration, and existing data. Laboratory testing: conducting physical and mechanical property tests on drill cores and the filling material of the isolation layer structural planes, including density and uniaxial compressive strength.

[0066] Water-conducting fault 11: The fault's occurrence and distribution characteristics are generally obtained based on existing hydrogeological and engineering geological exploration reports from the mine. Here, we only conduct further drilling and geophysical exploration in the corresponding area based on the mine's exploration results and deploy isolation layers to ensure safety. The specific coordinates of the constructed shaft 1, developed horizontal tunnel 2, developed inclined ramp 4, private mining shaft 6, private mining adit 7, private mining blind shaft 8, and private mining developed horizontal tunnel 9 will be collected and organized based on existing data. Historical mining data collection and preliminary analysis: Outlining the approximate scope, mining strata, and active period of private mining activities. Surface and near-surface field investigation 16: For all types of goaf areas, efficient and wide-coverage geophysical methods are first used for regional scanning. Obtaining geophysical anomaly maps, delineating the planar location and approximate range of suspected goaf anomalies, provides targets for subsequent precise detection. For detailed underground exploration and verification, engineering drilling is used to drill into key anomaly locations, and accurate exploration is conducted based on core samples. The morphology and structure of the void are constructed using technologies such as borehole television and void scanning.

[0067] Goaf remediation is a crucial part of controlling and preventing goaf disasters. Existing remediation methods mainly include the rock collapse method, goaf filling method, pillar support method, isolation and sealing method, and combined methods. Their essence is to alleviate the degree of stress concentration in the rock mass and ensure safe and sustainable mine production. Due to the influence of factors such as the time of goaf formation, goaf size, shape, mining technology conditions, surrounding rock properties, and construction difficulty, the appropriate remediation method should be selected based on specific circumstances.

[0068] In some embodiments, the treatment method includes: reinforcing the surrounding rock 17 with a support system. The reinforcement measures of the support system include at least one of anchor bolt support, anchor mesh support, anchor cable support, and shotcrete support. That is, for areas of severely fractured surrounding rock 17 inside the isolation layer, the surrounding rock 17 can be reinforced and supported by the above-mentioned support methods.

[0069] In some embodiments, the treatment method further includes: setting up goaf sealing walls and drainage holes in the historical goaf area. The goaf sealing walls are arranged in the roadway area of ​​the surrounding rock 17, and the drainage holes are arranged at the bottom of the goaf sealing walls. The goaf area is the part that has been exposed but not filled. The goaf sealing walls are used to seal and isolate the goaf area on the side of the surrounding rock 17 of the roadway, effectively sharing the concentrated stress of the surrounding rock 17, restraining the continuous extension and fragmentation of the rock fissures around the roadway, improving the overall structural integrity and support stability of the surrounding rock 17 of the roadway, avoiding secondary geological disasters such as roadway spalling, roof subsidence, and sidewall collapse caused by long-term stress release in the vacant historical goaf area, and building a solid safety defense line for the passage of underground roadways. In addition, the sealing and sealing of the walls can effectively prevent the accumulation of toxic, harmful, flammable and explosive gases such as methane and carbon monoxide in the historical vacant goaf area from flowing and spreading into the working roadway. Drainage holes are installed at the bottom of the sealed wall to automatically guide and drain water accumulated in the old goaf, seepage water from fissures, and water seepage from the surrounding rock 17. This quickly reduces the water pressure and water content of the surrounding rock 17, preventing long-term soaking and softening of the surrounding soil and rock mass and weakening of the rock mass's mechanical strength. It avoids water hazards such as water inrush, water seepage, and water inrush from the roadway floor in the goaf from the source. It is suitable for long-term drainage and maintenance of unfilled goaf areas, eliminating the need for large-scale excavation, backfilling, and grouting. The construction process is simple, highly adaptable to the site, and has a short construction period. This reduces the construction cost and manpower and material resources required for the special treatment of goaf areas in old mining areas, completes the closed-loop treatment of existing goaf hazards, and improves the efficiency of underground rock and soil disaster treatment.

[0070] In some embodiments, the treatment method further includes: providing drainage ditches and drainage systems within the static isolation layer 1501 and the temporary isolation layer 1502.

[0071] To ensure the isolation layer structure remains dry and stable during service and to effectively control groundwater pressure, a drainage system with ditches and drainage channels must be systematically installed within it. Layered and graded drainage is implemented, with the static isolation layer 1501 typically more permanent and the temporary isolation layer 1502 having a shorter lifespan, forming a three-dimensional drainage system. The layout of the drainage ditches must be integrated with the cross-sectional shape, slope, and support method (such as shotcrete or lining) of the roadway 14 (or chamber) along the vein to avoid affecting structural safety. While meeting slope requirements, gravity flow should be utilized as much as possible to reduce the energy consumption of mechanical drainage. The design must consider the convenience of dredging and inspection, especially in sections prone to sediment buildup, to facilitate maintenance.

[0072] Among them, ① the open drainage ditch system in the roadway (or chamber) is usually arranged longitudinally along the side wall or the center of the floor slab of the roadway. The cross-section is mostly rectangular or trapezoidal, wider at the top and narrower at the bottom, which is easy to clean. In the main passage with frequent personnel or equipment passage, heavy-duty grating covers should be added to ensure safety and passage. ② the pressure reduction drainage system inside the surrounding rock 17: mainly used to reduce the pore water pressure or fracture water pressure of the static isolation layer 1501 or temporary isolation layer 1502 (such as the roof, high stress area, near the potential slip surface). Drainage holes (pressure relief holes) are set up, and upward, horizontal or downward holes are drilled from inside the roadway to the surrounding rock 17. The layout pattern can be fan-shaped, radial or parallel. In water-rich areas such as fault zones and fracture zones, the density needs to be increased. Filter pipes (flower pipes) are installed at the hole openings to prevent rock debris from clogging, and water is connected to the water inlet pipe to guide the water into the nearby drainage ditch or sump. ③ water collection and drainage system: sump is set up at the low-lying areas or ends of the drainage network. For permanent works such as the static isolation layer 1501, a permanent water tank can be installed and equipped with a filter grate. The volume of the sump pit must meet the water storage requirements for a certain period of time to prevent frequent start-stop of the water pump. The drainage pipe is laid along the roadway wall, fixed reliably, and finally discharges the water to the main drainage system of the mine area or the surface treatment station 16. ④ Waterproofing and water interception auxiliary measures: In the roof or sidewalls where water seepage is severe, a waterproof coating can be sprayed or a waterproof membrane can be laid to guide the water to a pre-installed semi-circular water guide pipe or drainage ditch, and then into the drainage ditch, to avoid water overflow affecting the stability of the surrounding rock 17 and the working environment.

[0073] In some embodiments, the remediation method further includes: cemented backfilling of the fully mined waterlogged goaf 1201 and the unfilled goaf 1204; conducting seismic sand liquefaction risk assessment on the waste rock-filled goaf 1202 and the tailings-filled goaf 1203; and reinforcing the goaf if the assessment results do not meet safety standards. The seismic sand liquefaction risk assessment method is based on the "Code for Geotechnical Investigation" (GB 50021).

[0074] Among these, the risk assessment of seismic sand liquefaction can: ① Reveal potential instability risks. Waste rock backfill and some poorly cemented tailings backfill, under saturated or high water content, have loose structures and weak interparticle contact forces. Under cyclic shear loads such as earthquakes, pore water pressure rises sharply, and effective stress drops sharply, causing the backfill to instantly lose strength and liquefy, manifesting as flow or settlement. The assessment aims to quantify this risk. ② Ensure overall structural safety. Once the backfill in the goaf liquefies, the overlying rock strata will lose support, potentially triggering large-scale settlement, collapse, or even a chain reaction of ground pressure disasters, endangering the safety of the upper isolation layer, adjacent mining areas, and surface facilities. ③ Guide targeted remediation decisions. The risk assessment results provide a direct scientific basis for deciding whether to reinforce the backfill and what reinforcement scheme to adopt. This avoids safety hazards caused by insufficient remediation and prevents resource waste caused by excessive remediation. ④ Meet regulatory and design requirements. Modern mine safety regulations and seismic design codes for engineering projects typically require a liquefaction risk assessment for loose saturated fill or backfill in seismically active zones.

[0075] It is understandable that during the earthquake sand liquefaction risk assessment of the isolation layer, in order to ensure the stability of the safe isolation layer, it is necessary to analyze whether there is earthquake sand liquefaction within the isolation layer, to ensure that there is no risk of sand liquefaction within the isolation layer, and to ensure the safety performance of the isolation layer. When the risk of sand liquefaction is assessed in the isolation layer, the reinforcement support structure within the isolation layer can be strengthened.

[0076] The use of multiple prevention and control methods can improve the safety of the static isolation layer 1501 and the temporary isolation layer 1502, forming a stable and reliable regional isolation structure. This can effectively improve the stress distribution of the surrounding rock 17 around the goaf, enhance the overall stability of the surrounding rock 17, avoid problems such as roof subsidence and roadway deformation caused by historical goaf during the mining of the ore body 10, and reduce support costs and maintenance workload.

[0077] The following will be described using a specific embodiment.

[0078] The mining area is sized with a layer height ranging from 40.0m to 80.0m.

[0079] The vertical thickness of the static isolation layer 1501 is 40.0m, and the maximum airflow velocity vmax of the static isolation layer 1501 with this thickness is 3.23 m / s.

[0080] For example, the vertical thickness of the upper static isolation layer 1501 is 40.0m, which is equal to the design mid-section height of the mine. Since the mid-section heights are different in different mines, the vertical thickness of the upper static isolation layer 1501 is set according to the actual engineering design of the mine. It is convenient to monitor and control the overall state of the isolation layer if it is consistent with the design mid-section height of the mine.

[0081] In this embodiment, the temporary isolation layer 1502 is the area extending horizontally outward from the boundary of the ore body 10, with a horizontal thickness of 50.0m.

[0082] Based on the fractured condition of the surrounding rock 17 in the isolation layer, support was provided within the isolation layer. Mortar anchors were used for anchor support, with specifications of φ22mm×2200mm and a spacing of 1.0m×1.0m. Reinforcing mesh support used woven steel mesh with specifications of φ6.5mm×100mm×100mm and a mesh size of 1.0m×1.0m. Anchor cable support used anchors with specifications of φ21.8mm×5.0m and a spacing of 2.0m×2.0m. Shotcrete was C20 with a thickness of 20mm.

[0083] The goaf sealing wall is set at the connection between the goaf and the roadway, and corresponds to the sealing of the goaf. The goaf sealing wall is made of reinforced concrete, with a single layer of steel mesh arranged inside the wall. The mesh spacing is 0.5m×0.5m, and φ12mm steel bars are tied on site. The steel bars are welded to the anchor rods on both sides of the sealing wall. The anchor rods are made of φ20mm round steel, with a length of not less than 1.5m, an exposed length of 0.5m, and an anchor rod spacing of 0.5m.

[0084] The sealing wall of the goaf should have 1-3 drainage holes or drainage pipes reserved at a distance of about 30cm from the bottom of the roadway, with a pipe diameter of not less than 10cm.

[0085] The advance distance for advance water exploration is 50m; each working face is equipped with 5 advance water exploration holes, including 1 for the roof, 2 for the sidewalls, and 2 for the bottom; the drilling depth of the water exploration holes is 60m, with an opening diameter of not less than Ф110mm and a final hole diameter of not less than Ф75mm, and multiple advance water exploration holes are set around the cross section of the roadway.

[0086] After the water exploration work is completed in the exploration borehole, grouting and water plugging operation is carried out. The grouting materials used for water plugging are single-liquid cement grout and cement-water glass double-liquid grout. The grouting pressure is 7.5MPa, the injection volume per borehole is 10.41m3, and the grout diffusion radius is 5-10m.

[0087] The mine safety isolation layer setting method provided in this application can effectively isolate the mining area and significantly reduce safety risks. It fundamentally and effectively prevents potential safety hazards that may be induced by historical goaf areas in the mine, and has the characteristics of safety and stability, controllable risks, and effective prevention and control.

[0088] The mine safety isolation layer setting method provided in this application has good adaptability and can be flexibly adjusted and customized according to the geological conditions, mining methods, goaf distribution characteristics and other conditions of different mines. It can play a stable and reliable isolation and protection role in complex environments such as hard rock or soft strata, and has broad application prospects.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for setting up a safety isolation layer in a mine, characterized in that, include: The mining area of ​​the mine is delineated, and the mining area is then mined in a downward stratified manner. The area located above the mining area with a predetermined thickness is used as a static isolation layer, and the historical goaf and water-conducting faults within the static isolation layer are identified and treated. Within each layer, temporary isolation layers are set around the ore body to be mined, and historical goaf areas and water-conducting faults within the temporary isolation layers are explored and treated.

2. The method for setting up a mine safety isolation layer according to claim 1, characterized in that, The static isolation layer is a layered, dense solid with thickness arranged horizontally. Its thickness is calculated using the following formula: ; Where H is the thickness of the static isolation layer; α is an empirical correction coefficient, with a value ranging from 0.8 to 1.5; The maximum expected impact stress; For safety margin, the value ranges from 1.5 to 2.0; The density of the static isolation layer material is given; g is the acceleration due to gravity. The internal friction angle of the material constituting the static isolation layer.

3. The method for setting up a mine safety isolation layer according to claim 2, characterized in that, The static isolation layer consists of surrounding rock and ore body, and also includes at least one of cemented backfill goaf and cemented backfill goaf of domestic mining tailings.

4. The method for setting up a mine safety isolation layer according to claim 1, characterized in that, A temporary isolation layer is set up around the ore body to be mined. The temporary isolation layer is an area no more than 10m to 50m away from the ore body in the horizontal direction. And / or, the upper part of the temporary isolation layer is an upper developed horizontal tunnel or the upper surrounding rock, and the lower part of the temporary isolation layer is a lower developed horizontal tunnel or the lower surrounding rock.

5. The method for setting up a mine safety isolation layer according to claim 1, characterized in that, After the ore body in a certain layer is completely mined, the goaf is cemented and filled, and the historical goaf and water-conducting faults in the layer are explored and treated, so that the layer and the previous layer or static isolation layer are combined to form a new static isolation layer.

6. The method for setting up a mine safety isolation layer according to claim 1, characterized in that, Historical mining subsidence areas include constructed vertical shafts, developed horizontal tunnels, developed inclined ramps, private mining vertical shafts, private mining adits, private mining blind vertical shafts, private mining developed horizontal tunnels, completed private mining waterlogged subsidence areas, private mining waste rock filled subsidence areas, private mining tailings cemented filled subsidence areas, and private mining unfilled subsidence areas.

7. The method for setting up a mine safety isolation layer according to any one of claims 1 to 6, characterized in that, The safety of static and temporary isolation layers is investigated using at least one of the following methods: field investigation, engineering drilling, engineering geophysical exploration, theoretical analysis, laboratory testing, and numerical simulation.

8. The method for setting up a mine safety isolation layer according to any one of claims 1 to 6, characterized in that, Treatment methods include: reinforcing the surrounding rock with a support system, and the reinforcement measures of the support system include at least one of the following: anchor bolt support, anchor mesh support, anchor cable support, and shotcrete support.

9. The method for setting up a mine safety isolation layer according to any one of claims 1 to 6, characterized in that, The treatment methods also include: setting up goaf sealing walls and drainage holes in historical goaf areas, with the goaf sealing walls located in the roadway area of ​​the surrounding rock and the drainage holes located at the bottom of the goaf sealing walls; The treatment methods also include: setting up drainage ditches and drainage systems within the static isolation layer and the temporary isolation layer.

10. The method for setting up a mine safety isolation layer according to claim 6, characterized in that, The remediation methods also include: cementing and backfilling the waterlogged and unfilled mined areas of the fully mined private mines; conducting seismic sand liquefaction risk assessments on the mined areas filled with waste rock and the mined areas filled with cemented tailings from the private mines; and reinforcing the areas if the assessment results do not meet the safety standards.

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