Recovery method for actively controlling high-end wall stope of broken surrounding rock

Abstract

The invention discloses a stoping method for actively controlling a broken surrounding rock high-end wall stope, and relates to the technical field of mining. The stoping method comprises the steps that before stoping of a stope, surrounding rock in a high-end wall area is reinforced, and a reinforcing belt is constructed; an isolation belt is constructed on the side, close to the ore body, of the reinforcing belt through blasting; mining the ore body in different areas by adopting a retreating blasting method; and filling the exposed goaf after the ore body is mined every time. According to the stoping method for actively controlling the broken surrounding rock high-end wall stope, bolting and grouting reinforcement is actively conducted on the broken surrounding rock at the ore-rock junction before mining, the end wall rock mass structure is strengthened, and slice falling or collapse of the end wall rock mass structure is prevented; an isolation belt is constructed on the inner side of the reinforcing belt through presplitting blasting to prevent blasting energy from impacting broken ore rocks on the end wall; in the mining process, blasting is conducted in different areas, and step-by-step control over blasting disturbance is achieved; a mining area is filled in time after mining, and quadruple active prevention and control means are combined and utilized, so that the whole mining process is safe and stable, and the construction safety risk is greatly reduced.

Description

Technical Field

[0001] This application relates to the field of mining technology, and in particular to a method for actively controlling the mining of high-end wall-cut mines in fractured surrounding rock. Background Technology

[0002] In the process of converting open-pit mining to underground or deep underground mining of metallic and non-metallic minerals, the working face often needs to be advanced to the edge of the ore body, that is, the boundary area between the ore body and the surrounding rock. Due to the long-term influence of geological tectonic activity, the surrounding rock in this area generally has characteristics such as poor rock integrity, dense development of joints and fissures, and significantly reduced rock strength.

[0003] Under mining disturbances, engineering factors such as blasting vibration, stress redistribution, and unloading rebound further exacerbate the fracturing of the surrounding rock, severely reducing its self-stabilizing capacity. Once the high-end wall of the stope formed under the above geological and engineering environment becomes unstable, it is extremely easy to trigger catastrophic accidents such as roof collapse, sidewall spalling, or even large-scale landslides. Summary of the Invention

[0004] In view of this, this application provides a method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock, with the aim of solving one of the technical problems in the prior art.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides a method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock, comprising: Before mining, the fractured surrounding rock in the high-end wall area is reinforced and a reinforcement zone is constructed. An isolation zone is constructed on the side of the reinforcement zone closest to the ore body using pre-splitting blasting. The retreat blasting method was used to extract the ore body in sections. After each mining operation, the exposed goaf is filled in.

[0006] In an optional implementation, before the mining area is back-mined, the external roadway is used as a construction platform to drill anchor cable holes from the external roadway into the fractured surrounding rock of the high-end wall area. Grouting is injected into the anchor cable holes to cement the rock mass fissures; After grouting, long anchor cables are installed in the anchor cable holes, and pre-tightening force is applied to the long anchor cables.

[0007] In an optional implementation, the bottom of the anchor hole extends beyond the fractured surrounding rock area of ​​the upper wall.

[0008] In an optional implementation, before grouting, the distribution of rock fractures is detected and recorded by in-hole television or core drilling. After grouting, the cementation status of rock fractures is checked again by in-hole television or core drilling, and the grouting pressure is adjusted accordingly.

[0009] In an optional implementation, the steel strand at the bottom of the anchor cable hole is stripped of its outer sheath and degreased, and an enlarged head is made using an extrusion anchor. Apply grease to the outside of the steel strands in the fractured surrounding rock area of ​​the high-end wall and cover them with a flexible tube so that the tube can move relative to the steel strands.

[0010] In an optional implementation, pre-splitting blasting holes are arranged from the drilling roadway of the stope along the outline of the high-end wall of the stope, close to the ore body. The depth of the pre-splitting blasting holes is not less than the height of the high-end wall.

[0011] In an optional implementation, the pre-splitting blast holes employ a decoupled charging method; A shaped charge blasting device is installed inside the pre-splitting blasting hole, and the shaped charge slots of all the shaped charge devices are directed towards the adjacent pre-splitting blasting hole. After blasting, the blast holes are connected to form a pre-splitting surface.

[0012] In an optional implementation, during the mining process, the area to be blasted is divided into an end blasting zone near the high-end wall, a main blasting zone away from the high-end wall, and a transition zone between the end blasting zone and the main blasting zone. From the direction away from the high-end wall to the direction near the high-end wall, the charge per unit volume or per unit hole depth of the blast holes in each zone gradually decreases, and the hole density gradually increases.

[0013] In an optional embodiment, within the transition zone, the charge amount and the hole density of the boreholes change in a step-like or gradual manner. The blast holes in the end blasting zone and the transition zone are all inclined toward the goaf.

[0014] In an optional implementation, force, displacement, or vibration monitoring sensors are deployed in or near the reinforcement zone to monitor the vibration response of the high-end wall in real time during the mining blasting process. If the monitored vibration velocity or acceleration exceeds the preset safety threshold, the charge amount in the end blasting zone will be further reduced or the detonation network will be adjusted in subsequent blasting operations.

[0015] Compared with existing technologies, the beneficial effects of this application are as follows: This application proposes a method for actively controlling the mining of high-end wall mines in fractured surrounding rock, including reinforcing the surrounding rock in the high-end wall area and constructing a reinforcement zone before mining; constructing an isolation zone on the side of the reinforcement zone close to the ore body through blasting; using a retreating blasting method to open the ore body in sections; filling the exposed goaf after each mining operation; and actively reinforcing the fractured surrounding rock at the ore-rock interface with anchoring before mining to strengthen the end-wall rock mass structure and prevent it from flaked or collapsed. The system provides "static initial support" by creating a buffer zone within the reinforced zone through pre-splitting blasting, thus preventing the blasting energy from impacting the fractured ore and rock at the end wall. It also provides a "safety airbag" by constructing an isolation zone inside the reinforced zone during mining, thereby controlling the blasting disturbance step by step and reducing its impact on the end wall and reinforced structure of the stope. In addition, the mining area is promptly filled after mining to provide "dynamic temporary support." By combining these four active prevention and control measures, the entire mining process is made safe and stable, significantly reducing construction safety risks and improving resource recovery rates. Attached Figure Description

[0016] 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.

[0017] Figure 1 The flowcharts of the active control method for mining high-end wall mining in fractured surrounding rock in some embodiments of this application are shown; Figure 2 The following are schematic diagrams of the cross-sectional structure of the mining area in some embodiments of this application; Figure 3 This application shows a schematic diagram of the structure of the mining area at the blasting location in some embodiments; Flowchart; Figure 4 This application shows a schematic cross-sectional view of the long anchor cable in the mining area in some embodiments. Figure 1 ; Figure 5 This application shows a schematic cross-sectional view of the long anchor cable in the mining area in some embodiments. Figure 2 ; Figure 6 This application shows a schematic cross-sectional view of the long anchor cable in the mining area in some embodiments. Figure 3 ; Figure 7 The diagram shows a schematic representation of the blast hole structure in a mining area in some embodiments of this application.

[0018] Explanation of key component symbols: 110-Fractured surrounding rock; 120-Reinforcement zone; 130-Isolation zone; 140-Infill body; 150-High-end wall; 160-Ore body; 210-External roadway; 220-End blasting zone; 230-Main blasting zone; 240-Transition zone; 250-Long anchor cable; 251-Steel strand; 252-Extrusion anchor; 253-Hose hose; 260-Blast hole; 261-Pre-splitting blasting hole; 262-Pre-splitting surface; 263-Explosive; 264-Blasting mud. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] In related technologies, during the conversion from open-pit to underground or deep underground mining of metallic and non-metallic minerals, the working face often needs to be advanced to the edge of the ore body, i.e., the boundary area between the ore body and the surrounding rock. Due to the long-term influence of geological tectonic activity, the surrounding rock in this area generally has characteristics such as poor rock integrity, dense development of joints and fissures, and significantly reduced rock strength.

[0025] Instability of the upper mining wall not only leads to a large amount of waste rock being mixed into the ore, causing ore dilution and reducing beneficiation recovery rates, but also causes irreversible resource losses due to the burial of boundary ore by collapsed rock masses. More seriously, upper mining wall instability poses a major safety hazard to the mining area, posing a continuous threat to the safety of workers and equipment.

[0026] Under mining disturbances, engineering factors such as blasting vibration, stress redistribution, and unloading rebound further exacerbate the fracturing of the surrounding rock, severely reducing its self-stabilizing capacity. Once the high-end wall of the stope formed under the above geological and engineering environment becomes unstable, it is extremely easy to trigger catastrophic accidents such as roof collapse, sidewall spalling, or even large-scale landslides.

[0027] like Figure 1 As shown, embodiments of this application provide a method for actively controlling the mining of a stope with a 110-ton high-end wall and a 150-ton high-end wall in fractured surrounding rock. The method for actively controlling the mining of a stope with a 110-ton high-end wall and a 150-ton high-end wall in fractured surrounding rock includes: Step S10: Before mining in the stope, the broken surrounding rock 110 in the high-end wall 150 area is reinforced and a reinforcement zone 120 is constructed.

[0028] Before mining, the high-end wall 150 itself was reinforced by building a high-strength reinforcement zone 120, which enhanced the strength and stability of the rock wall itself, forming a reinforcement zone 120 with initial bearing capacity, and reducing the occurrence of instability of the high-end wall 150.

[0029] Step S20: Construct an isolation zone 130 on the side of the reinforcement zone 120 close to the ore body 160 by pre-splitting blasting.

[0030] The isolation zone 130 is used to absorb and block the energy transmitted during large-scale blasting in the mining process, and to protect the surrounding rock in the high-end wall 150 area to reduce instability.

[0031] Step S30: The retreating blasting method is used to mine the ore body 160 in sections.

[0032] The ore body 160, which is close to the high-end wall 150 and far from the high-end wall 150, is divided into zones, and different mining methods are used for different zones to achieve precise mining that balances efficiency and safety.

[0033] In step S40, after each mining of the ore body 160, the exposed goaf is filled, and the goaf will form a filling body 140.

[0034] After each blast, ore is quickly extracted, and within a short period (e.g., 24 to 72 hours), the exposed goaf is filled with backfill materials (such as waste rock, water-sand backfill materials, and cemented backfill materials). After backfilling, a solid "artificial wall" is formed, supporting the exposed rock wall (such as the hanging wall), promptly distributing the support pressure of the reinforced zone 120, making the entire mining process safe and stable, significantly reducing construction safety risks, and improving resource recovery rate.

[0035] Furthermore, in existing technologies, support treatment for the high-end wall 150 area often occurs after the ore body 160 has been mined to the point where the high-end wall 150 is exposed, representing a passive protective measure. Common support methods involve installing anchor bolts and shotcrete on the rock face of the high-end wall 150. However, traditional anchor bolt support, mesh anchor support, or shotcrete techniques are insufficient to effectively reinforce deep, fractured rock masses. The effectiveness of such support systems is typically limited to the surface layer of the rock mass, failing to fundamentally improve the overall structural load-bearing capacity of the high-end wall 150.

[0036] Compared to the passive high-end wall 150 control method in related technologies that involves mining first and then supporting, this application actively reinforces the structure of the surrounding rock in the high-end wall 150 area before mining, providing "static initial support"; and constructs an isolation zone 130 on the side of the high-end wall 150 close to the ore body 160 before mining to block blasting energy, providing a "safety airbag"; performs zoned blasting during mining to achieve "precise mining"; and promptly fills the mining area after mining to provide "dynamic temporary support". By combining these four active control measures, the entire mining process is safe and stable, significantly reducing construction safety risks and improving resource recovery rate.

[0037] In some embodiments, step S10 further includes: Step S11: Before mining in the stope, use the external tunnel 210 as a construction platform to drill anchor cable holes from the external tunnel 210 to the fractured surrounding rock 110 in the high-end wall 150 area.

[0038] In one embodiment, reference Figure 2 As shown, multiple anchor holes form a fan-shaped structure, allowing the multiple anchor holes to match the potential failure modes of the end wall to maximize load-bearing capacity. The failure modes of the end wall include at least three types: 1. Gravity-induced fall (block fall): Anchor cables are arranged vertically to maximize tensile strength against gravity; 2. Sliding failure: The anchor cable is aligned with the shear plane, but at an angle of 17° to 27° to generate maximum shear strength; 3. Plate cracking and buckling failure, with anchor cables arranged perpendicular to foliation and bedding to clamp the rock strata.

[0039] Multiple anchor holes in the fan-shaped structure are installed in the anchoring tunnel parallel to the wall and perpendicular to the end wall, which has a better pre-reinforcement effect.

[0040] Step S12: Grout into the anchor cable hole to cement the rock mass fissures.

[0041] Taking the construction of a 250mm long anchor cable as an example, the anchor cable drilling is carried out vertically, with a total of 5 rows, a row spacing of 1.0m, a row spacing of 2.0m, and staggered arrangement, with 5-6 holes in each row. The diameter of the drill hole is Φ75mm, and the diameter of the anchor cable is 17.8mm.

[0042] Before constructing the anchor cables, the surrounding rock is reinforced by grouting. The grouting hole diameter is 75mm. To ensure successful hole formation within the fractured rock mass, grouting is performed simultaneously with drilling to effectively prevent hole collapse. Continuous grouting is crucial, with a water-cement ratio of 0.4 to 0.5. P.O42.5R ordinary Portland cement is used. The final grouting pressure should be no less than 6MPa to avoid underpressure leading to hole wall damage or incomplete grouting. This ensures the grouting density of the fractured surrounding rock (110mm) and guarantees full grouting of the fractured rock strata. For the full-length grouting anchor cable construction, a 300mm×300mm×16mm tray is used. A sealing device is installed at the hole opening, and the inner end of the vent pipe is placed at the bottom of the hole. The grouting pressure should be no less than 6MPa. After grouting, wait 24 hours for the cement grout to solidify before installing the pad and anchor at the anchor cable hole location. The pre-tightening force of the anchor should be no less than 100KN during installation. Step S13: Install the long anchor cable 250 in the grouted anchor cable hole and apply a preload to the long anchor cable 250. The preload shall not be less than 100 kN.

[0043] Through steps S11 to S13, grouting long anchor cables 250 are constructed from a safe position in the external tunnel 210 into the fractured surrounding rock 110 corresponding to the external tunnel 210. First, high-pressure grouting is used to fully inject grout into the rock fissures, achieving cementation of the fractured rock mass and fundamentally improving its integrity and strength. Then, by installing the long anchor cables 250 and applying prestressing force, the anchor cables are immediately put into a tensioned state. In this way, the cemented rock mass and the prestressed anchor cables together form a composite "reinforcement zone 120" with high rigidity and initial bearing capacity.

[0044] In other words, it is equivalent to using anchor cables as steel bars and grout and fractured rock mass as cement to form a "reinforced concrete" reinforced structure. Compared with the structure that only uses anchor cable support in related technologies, such a structure can greatly enhance the strength and stability of the rock wall in the high-end wall 150 area and greatly reduce the occurrence of instability of the high-end wall 150.

[0045] In some embodiments, the bottom of the anchor hole extends beyond the fractured surrounding rock 110 region of the upper wall 150.

[0046] like Figure 2 and Figure 3 As shown, the bottom of the anchor cable hole is positioned on the left side of the fractured surrounding rock 110 region of the high-end wall 150, meaning the anchor cable hole penetrates the high-end wall 150 region and extends into the ore body 160. The anchor point of the anchor cable is then placed on the ore body 160. Thus, when a preload is applied to the anchor cable, it is equivalent to pressing the entire high-end wall 150 region outwards towards the surrounding rock, forming a "hard-soft-hard" interlayer structure, such as... Figure 2 The ore body 160 on the left and the surrounding rock on the right sandwich the high-end wall 150 area in the middle. This sandwiches the surrounding rock of the high-end wall 150 area, which is prone to instability and collapse, between two relatively rigid structures, thereby improving structural stability and significantly reducing construction safety risks.

[0047] In some embodiments, the depth of the anchor cable hole is 15-20 meters, and the depth of the anchor cable hole extending into the ore body 160 is 3-10 meters.

[0048] In some embodiments, before grouting, the distribution of rock fractures is detected and recorded by in-hole television or core drilling; after grouting, the cementation state of rock fractures is detected again by in-hole television or core drilling, and the grouting pressure is adjusted.

[0049] It is easy to understand that by introducing image processing technology (such as the degree of rock mass fracture and the distribution of fissures), visual information is transformed into quantifiable "grouting effectiveness indicators," which in turn determine the grouting pressure settings for the next grouting cycle or adjacent areas. This enables dynamic iteration of "construction, testing, and optimization simultaneously," improving grouting uniformity, reducing ineffective grouting, and enhancing the controllability of grouting operation quality.

[0050] In related technologies, the steel strand 251 at the bottom of the anchor cable hole has low bonding strength with concrete or grouting material because it has not undergone special treatment, which can easily lead to anchorage failure.

[0051] To address the above issues, in some embodiments, reference is made to Figure 4 As shown, the steel strand 251 at the bottom of the anchor cable hole is stripped of its outer layer and oil removed, and an enlarged head is made using an extrusion anchor 252.

[0052] In one embodiment, such as Figure 4 and Figure 5 As shown, the grease layer on the surface of the steel strand 251 is removed using chemical solvents, and the oxide layer is removed by mechanical scraping. A hydraulic extrusion anchor 252 is used, which uses high pressure to extrude the end of the steel strand 251 into an enlarged head shape to increase the anchoring area and enhance the anchoring effect.

[0053] In the high-end wall 150 area, the steel strand 251 will generate a large frictional force with the borehole wall. Especially when the rock mass in the high-end wall 150 area is relatively soft, this frictional force may cause damage to the steel strand 251, thereby affecting the overall performance and service life of the anchor cable.

[0054] To address the above issues, in some embodiments, reference is made to Figure 5 and Figure 6 As shown, grease is applied to the outside of the steel strand 251 in the high-end wall 150 area, and a flexible tube 253 is fitted over it, allowing the flexible tube 253 to move relative to the steel strand 251.

[0055] The flexible hose 253 is made of a wear-resistant and flexible material, such as polyethylene or polyurethane, and serves as an extension of the steel strand 251. When the surrounding rock in the high-end wall 150 area moves, the hose 253 moves along with the surrounding rock, extending the length of the steel strand 251, releasing the stress caused by the rock movement, protecting the anchor cable, reducing anchor cable deformation, and extending the service life of the anchor cable 250.

[0056] In some embodiments, reference Figure 7 As shown, pre-splitting blasting holes 261 are arranged along the outline of the high-end wall 150 of the mining area, close to the ore body 160, from the rock drilling roadway of the mining area. The depth of the pre-splitting blasting holes 261 is not less than the height of the high-end wall 150.

[0057] In one embodiment, such as Figure 7 As shown, pre-splitting blasting holes 261 are drilled 1-2 meters off the inner side of the outline of the high-end wall 150 of the stope towards the ore body 160 from the drilling roadway of the stope. Deep-hole blasting is used for pre-splitting blasting, with the spacing of the pre-splitting blasting holes 261 between 300-700 mm. The isolation zone 130 formed by the blasting of the pre-splitting blasting holes 261 is designed to cover the entire height of the high-end wall 150, reducing the risk of insufficient depth of the pre-splitting blasting holes 261 affecting the stability of the high-end wall 150 and thus preventing safety hazards.

[0058] In some embodiments, the pre-splitting blast hole 261 adopts a decoupled charging method.

[0059] In one embodiment, the decoupled charging method is as follows: a charge cartridge with a diameter smaller than that of the pre-splitting blast hole 261 is used, and the charge cartridge is filled with stemming material 264 to achieve decoupled charging, improve the pre-splitting effect and reduce damage to the surrounding rock mass.

[0060] like Figure 7 As shown, the pre-splitting blasting hole 261 adopts an alternating deep and shallow hole charging method. The pre-splitting blasting hole 261 includes deep holes and shallow holes, which are distributed alternately. Due to the 2-3m of stemming material 264 blocking the outside of the deep hole blasting, the overall cutting effect is affected, thus making it impossible to achieve smooth ore falling. Increasing the number of shallow holes can increase the pre-splitting effect on the end of the stemming material 264.

[0061] In some embodiments, a shaped charge blasting device is installed in the pre-splitting blast hole 261, and the shaped charge slots of all shaped charge devices are directed toward the adjacent pre-splitting blast hole 261. After blasting, the blast hole 260 is completed to form a pre-splitting surface 262.

[0062] When ordinary 263 explosive detonates, the explosive energy radiates evenly in all directions, producing roughly equal crushing and destructive effects on the rock surrounding the borehole. A shaped charge blasting device involves installing a device (shaped charge tube or shaped charge) with a shaped charge groove (a V-shaped or semi-circular groove) onto the 263 explosive. During detonation, the explosive energy is preferentially concentrated along the axis of the shaped charge groove, forming a high-speed, high-pressure, high-energy jet or shaped charge flow. The destructive force of this energy beam far exceeds that in other directions, achieving the goal of controlling the direction and number of cracks created by the blast.

[0063] In addition, the direction of the energy-concentrating slots of all energy-concentrating devices is directed towards the adjacent pre-splitting blasting holes 261 to enhance the pre-splitting effect.

[0064] In some embodiments, during the mining of the ore body 160, the area to be blasted is divided into an end blasting zone 220 near the high-end wall 150, a main blasting zone 230 away from the high-end wall 150, and a transition zone 240 located between the end blasting zone 220 and the main blasting zone 230. From the direction away from the high-end wall 150 to the direction near the high-end wall 150, the charge per unit volume or per unit hole depth of the blast holes 260 in each region gradually decreases, and the hole density of the blast holes 260 gradually increases, so as to have little impact on the structural stability of the high-end wall 150 region and prioritize blasting efficiency; in the region near the high-end wall 150, priority is given to reducing disturbance to the high-end wall 150 and improving the stability of the high-end wall 150 region.

[0065] In some embodiments, an end blasting zone 220 domain is provided near the high-end wall 150, a main blasting zone 230 domain is provided away from the high-end wall 150, and a transition zone 240 domain is provided between the end blasting zone 220 domain and the main blasting zone 230 domain. In one embodiment, the end blasting zone 220 refers to the area 150.5~5m away from the high wall of the ore body 160, the transition zone 240 refers to the area 150 away from the high wall of the ore body 160, and the main blasting zone 230 refers to the area 150 away from the high wall of the ore body 160.

[0066] In one embodiment, the charge per unit blast volume or per unit hole depth in the end blasting zone 220 is reduced by 10-50% compared to the main blasting zone 230, and the hole density in the end blasting zone 220 is increased by 15-40% compared to the main blasting zone 230.

[0067] In some embodiments, within the transition zone 240, the charge amount and the hole density of the boreholes 260 vary in a step-like or gradual manner. By setting the transition zone 240, a smooth transition of blasting energy from strong to weak is achieved.

[0068] Main blasting zone 230 (150 to 15m from the high wall): Ø80mm diameter boreholes are used, with 260 boreholes spaced 2.0m apart, and the unit explosive consumption is 0.4kg / t.

[0069] Transition zone 240 (150 to 5m from the high wall): In this area, the spacing of the 260 blast holes is reduced to 1.5m, and the unit explosive consumption is reduced to 0.3kg / t.

[0070] End blasting zone 220 (150.5m to 5m from the high wall): In this zone, the spacing of the blast holes 260 is reduced to 1.0m, and the unit explosive consumption is reduced to 0.2kg / t.

[0071] In some embodiments, the blast holes 260 in both the end blasting zone 220 and the transition zone 240 are inclined toward the goaf. For example... Figure 2 As shown, the blast hole 260 is tilted so that the blasted ore naturally rolls down into the goaf, reducing the pressure on the rock wall.

[0072] In some embodiments, the blast holes 260 are all inclined at an angle of 5-15° toward the goaf, so that the ore blasted off the end blasting zone 220 slides down along the pre-splitting surface 262.

[0073] In some embodiments, force, displacement, or vibration monitoring sensors are deployed in or near the reinforcement zone 120 to monitor the vibration response of the high-end wall 150 in real time during the mining blasting process; if the monitored vibration velocity or acceleration exceeds a preset safety threshold, the charge amount in the end blasting zone 220 is further reduced or the detonation network is adjusted in subsequent blasting operations.

[0074] By introducing zoned differentiated blasting, a parameter transition zone of 240, and a dynamic feedback adjustment mechanism based on real-time monitoring, blasting design is no longer static, but an intelligent process that can adaptively optimize according to the real-time response of the rock mass, thereby minimizing mining disturbance.

[0075] This application utilizes a complete technical chain of "active reinforcement (setting reinforcement zone 120) - pre-isolation (setting isolation zone 130) - fine mining (zonal blasting) - rapid support (rapid backfilling after mining)", which is closely linked to each other and greatly eliminates the major safety hazard of instability of the high-end wall 150 of the broken mine, providing a solid technical guarantee for the safe, continuous and efficient production of the mine.

[0076] Because the stability of the high-end wall 150 is effectively controlled, the mixing of waste rock and the loss of boundary ore are avoided, thereby significantly reducing the ore dilution rate, improving the resource recovery rate, and increasing economic benefits.

[0077] This implementation method is applied to an underground metal mine, using a segmented open-pit mining method followed by backfilling.

[0078] The target stope dimensions are: 400m long, 8m wide, and 1m high. One end of the stope (i.e., the end where the high-end wall 150 is formed at the end of mining) is in contact with the surrounding rock, which is a fractured phyllite with well-developed joints and fissures, an RQD value of less than 50%, and extremely poor self-stabilizing ability.

[0079] The active control method for mining the 110 high-end wall 150 stope in this embodiment is implemented according to the following steps: Step 1: Pre-construct reinforcement strip 120.

[0080] 1. Roadway Preparation and Drilling: Before the start of mining operations, the external transport roadway, parallel to the outline of the 150-meter high-end wall of the stope, is used as a construction platform. A rock drilling rig is used to drill anchor cable holes with a diameter of Ø75mm into the fractured surrounding rock 110 within the 16m high high-end wall 150 area to be formed. The holes are arranged in a 2.5m × 2.5m rectangular grid, with a designed depth of 15-20m, ensuring that the anchor cable anchoring section extends at least 5m into the relatively intact ore body 160 behind the high-end wall 150.

[0081] 2. Feedback-type high-pressure grouting: ① Initial grouting and testing: Initial grouting was performed on the first three test boreholes, using the PQt (pressure-flow-time) method for control, with the initial grouting pressure set at 3.5 MPa. After grouting, once the grout had initially set, a Ø75 mm test hole was drilled between the test boreholes. An in-hole television imaging device was lowered into the hole to observe and record the filling of internal fractures in the rock mass.

[0082] ② Parameter Feedback Adjustment: Test results showed that some micro-fractures were not completely filled with grout. A feedback-based adjustment and control method was implemented, deciding to increase the grouting pressure for subsequent large-area construction by 1.5 MPa, adjusting it to 5.0 MPa. Simultaneously, during formal construction, after grouting every 20 holes, a test hole was randomly drilled for core sampling. The cementation quality of the rock core was used to verify the grouting effect and ensure that the rock mass cementation met design requirements.

[0083] 3. Installation of 250mm long grouting anchor cables: Anchor cable preparation: Two Ø15.24mm steel strands 251 are bundled together to form a long anchor cable 250. The steel strands 251 at the end of the 1.5m anchoring section of the anchor cable are cleaned with solvent, stripped of oil, and then the enlarged head of the extrusion anchor 252 is made using a special extrusion machine. The 15m section of the anchor cable that passes through the fracture zone is evenly coated with anti-corrosion grease and then covered with a 3mm thick PVC flexible tube 253 as a free extension section.

[0084] Installation and secondary grouting: The prepared anchor cable is installed into the pre-grouted hole and secondary grouting (anchoring grouting) is performed.

[0085] Apply preload: After the anchor grout reaches 75% of its design strength (approximately 48 hours), apply a preload of 120 kN to the anchor cable using a hydraulic jack, and then lock it with the anchor.

[0086] Through the above operations, a solid "reinforcement zone 120" with initial load-bearing capacity was successfully pre-constructed at the junction of fractured ore and rock.

[0087] Step 2: Construct a blast damage isolation zone.

[0088] 1. Construction of pre-splitting holes: From the drilling roadway in the mining area, offset 1.5m from the designed outline of the high-end wall 150 towards the inner side of the ore body 160, drill a row of directional pre-splitting blasting holes 261 with a diameter of Ø50mm. The spacing of the pre-splitting holes is strictly controlled at 500mm, and the hole depth is 16m to ensure that the pre-splitting cracks can cover the entire height of the high-end wall 150.

[0089] 2. Decoupled shaped charge: A decoupled charging method is adopted, using No. 2 rock emulsion explosive 263 with a diameter of Ø32mm. To improve the directional effect, shaped charge devices are installed in the borehole, and it is ensured that the shaped charge slots of all shaped charge devices are precisely pointed to the adjacent pre-splitting holes.

[0090] 3. Independent detonation: All pre-splitting holes are detonated at once. The detonation operation is carried out one shift (8 hours) before the start of the main mining blasting in the stope, to ensure that the pre-splitting cracks have sufficient time to form and expand, thereby forming an effective "isolation zone 130" between the "reinforcement zone 120" and the ore body 160.

[0091] Step 3: Implement differentiated data collection by region.

[0092] 1. Dynamic monitoring system deployment: Within the reinforcement zone 120, anchor cable force gauges are installed on some of the grouting long anchor cables 250. Simultaneously, monitoring holes are drilled in the rock mass behind the high-end wall 150, and three-component vibration monitoring sensors are installed. The safe warning threshold for vibration velocity is set at 15 cm / s.

[0093] 2. For example Figure 3 As shown, the zonal blasting design: Main blasting zone 230 (150 meters from the high wall): Ø80mm boreholes are used, the row spacing of boreholes 260 is 2.0m, and the unit explosive consumption of 263 is 0.4 kg / t.

[0094] Transition zone 240 (150 from the high wall): In this area, the spacing between the 260 blast holes is reduced to 1.5m, and the unit explosive consumption is reduced to 0.3kg / t.

[0095] End blasting zone 220 (150.5m~5m from the high wall): In this area, the spacing of the blast holes 260 is reduced to 1.0m, and the unit explosive consumption is reduced to 0.2 kg / t.

[0096] 3. Inclined drilling: All deep holes are inclined at 10° toward the goaf (free face) to facilitate the collapse of ore and rock toward the goaf after blasting and reduce the pressure on the high-end wall 150.

[0097] 4. Monitoring Feedback and Adjustment: During the blasting of the first row of holes in the end blasting zone 220, the monitoring system showed that the vibration velocity near the high wall 150 reached 16.5 cm / s, exceeding the warning threshold. The blasting plan for the subsequent rows of holes was immediately adjusted: the unit explosive consumption was further reduced to 0.2 kg / t, the in-hole detonation network was optimized, and the micro-delay time was increased, successfully controlling the vibration velocity of the subsequent blasts below 12 cm / s.

[0098] Step 4: Provide dynamic and timely support.

[0099] After each blasting operation, a remote-controlled loader is immediately used to remove the ore, ensuring that all fallen ore is removed within 48 hours. After ore removal, preparations for filling the goaf are immediately made, and the filling operation is completed within 60 hours after the blasting, providing timely and effective support for the exposed high-end wall 150.

[0100] Implementation results: Through the above-described specific implementation methods, the high-end wall 150 in the fractured ore-rock interface mining area remained highly stable throughout the entire mining process, without any spalling or collapse. The final ore dilution rate was controlled below 5%, and the resource recovery rate reached 96%. Real-time monitoring data showed that the deformation and stress of the high-end wall 150 were within a controllable range, verifying the effectiveness, scientific nature, and safety of the method of this invention.

[0101] 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.

[0102] 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 actively controlling the mining of high-end wall mining areas in fractured surrounding rock, characterized in that, include: Before mining, the fractured surrounding rock in the high-end wall area is reinforced and a reinforcement zone is constructed. An isolation zone is constructed on the side of the reinforcement zone closest to the ore body using pre-splitting blasting. The retreat blasting method was used to extract the ore body in sections. After each mining operation, the exposed goaf is filled in.

2. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to claim 1, characterized in that, Before the mining area is back-mined, the external tunnel is used as a construction platform to drill anchor cable holes from the external tunnel to the fractured surrounding rock in the high-end wall area. Grouting is injected into the anchor cable holes to cement the rock mass fissures; After grouting, long anchor cables are installed in the anchor cable holes, and pre-tightening force is applied to the long anchor cables.

3. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to claim 2, characterized in that, The bottom of the anchor cable hole extends beyond the fractured surrounding rock area of ​​the high-end wall.

4. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to claim 2, characterized in that, Before grouting, the distribution of rock fractures is detected and recorded by in-hole television or core drilling. After grouting, the cementation status of rock fractures is checked again by in-hole television or core drilling, and the grouting pressure is adjusted accordingly.

5. The method for actively controlling the mining of high-end wall-mounted mining areas in fractured surrounding rock according to claim 2, characterized in that, The steel strands at the bottom of the anchor cable holes are stripped of their outer layer and degreased, and an enlarged head is made using an extrusion anchor. Apply grease to the outside of the steel strands in the fractured surrounding rock area of ​​the high-end wall and cover them with a flexible tube so that the tube can move relative to the steel strands.

6. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to any one of claims 1 to 5, characterized in that, Pre-splitting blasting holes are arranged along the outline of the high-end wall of the mining area, close to the ore body. The depth of the pre-splitting blasting holes is not less than the height of the high-end wall.

7. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to claim 6, characterized in that, The pre-splitting blast holes adopt a decoupled charging method; A shaped charge blasting device is installed inside the pre-splitting blasting hole, and the shaped charge slots of all the shaped charge devices are directed towards the adjacent pre-splitting blasting hole. After blasting, the blast holes are connected to form a pre-splitting surface.

8. The method for actively controlling the mining of high-end wall-mounted mining areas in fractured surrounding rock according to claim 6, characterized in that, During the mining process, the area to be blasted is divided into an end blasting zone near the high wall, a main blasting zone away from the high wall, and a transition zone between the end blasting zone and the main blasting zone. From away from the high wall to near the high wall, the charge per unit volume or per unit hole depth of the blast holes in each zone gradually decreases, and the hole density gradually increases.

9. The method for actively controlling the mining of high-end wall-mounted mining areas in fractured surrounding rock according to claim 8, characterized in that, Within the transition zone, the charge amount and the hole density of the boreholes change in a step-like or gradual manner. The blast holes in the end blasting zone and the transition zone are all inclined toward the goaf.

10. The method for actively controlling the mining of high-end wall mining areas in fractured surrounding rock according to any one of claims 1 to 5, characterized in that, Force, displacement, or vibration monitoring sensors are deployed in or near the reinforcement zone to monitor the vibration response of the high-end wall in real time during the mining blasting process. If the monitored vibration velocity or acceleration exceeds the preset safety threshold, the charge amount in the end blasting zone will be reduced or the initiation network will be adjusted in subsequent blasting operations.

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