Method for stoping gently inclined ore body and managing roof

Abstract

The invention relates to the technical field of mining engineering, in particular to a gently inclined ore body stoping and roof management method, which realizes cooperative control in the mining process by deeply fusing layered interval stoping, a composite filling technology and an intelligent monitoring-adaptive support system. A degradable fiber reinforced material and a novel filling formula are adopted, a distributed optical fiber-stress sensor mixed monitoring network and a top plate stability dynamic evaluation model are combined, the problems that traditional supporting is low in reliability, monitoring lags behind, ground pressure management is difficult and the like are effectively solved, compared with the prior art, the supporting cost can be reduced by 40%-60%, the filling efficiency is improved by 30%-45%, and the supporting effect is good. The mining safety and the resource recovery rate are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, specifically to a method for mining gently dipping ore bodies and roof management. Background Technology

[0002] In the mining of gently dipping ore bodies, the key to achieving safe and efficient mining lies in the synergistic optimization of mining technology and roof management. However, current technologies face numerous bottlenecks, severely hindering the industry's development.

[0003] In terms of support systems, traditional support materials and structures are ill-suited to complex geological conditions. While metal supports possess high strength, their cost remains high, and they are prone to plastic deformation under high stress. Timber supports, though less expensive, have limited load-bearing capacity and are highly susceptible to failure under fractured or composite roof conditions. Taking "soft" coal seam working faces as an example, single hydraulic props combined with articulated roof beams are typically used for support, requiring frequent secondary hydraulic injection to maintain initial support force and prevent roof collapse. However, in actual production, due to equipment aging and untimely maintenance, roof collapse accidents caused by support failure occur frequently. Statistical data shows that the roof accident rate in "soft" coal seam working faces using traditional support methods is 40-60% higher than under ideal support conditions.

[0004] In terms of monitoring methods, existing technologies mostly rely on empirical methods such as manual observation like "knocking on the roof and walls," which cannot obtain key data such as roof stress and displacement in real time, making it difficult to provide early warnings of roof instability risks. Although some mines have introduced technologies such as water injection softening and deep-hole pre-fracturing to treat hard roofs, these technologies have extremely high requirements for construction processes and require professional teams to operate, resulting in high management costs and significant fluctuations in effectiveness due to geological conditions. For example, when a certain iron mine used deep-hole pre-fracturing technology to treat a hard roof, the pre-fracturing effect was unstable due to changes in geological conditions, ultimately leading to a partial collapse of the roof, causing equipment damage and production interruption.

[0005] In the field of ground pressure management, goaf areas formed by room-and-pillar mining have long been prone to roof collapse, especially in deep mining where stress concentration in the pillars is prominent, easily leading to pillar instability and a chain reaction of roof failure. Although backfilling can effectively control ground pressure, existing backfilling processes have significant drawbacks: cemented backfilling requires large amounts of cement, resulting in high costs; water-sand backfilling easily causes mudding in underground roadways and equipment, affecting production efficiency; and high-concentration pumping technology for tailings backfilling is not yet fully mature, easily leading to pipeline blockage problems in practical applications. Furthermore, traditional caving methods easily cause surface subsidence, while improper backfilling can lead to groundwater pollution. For example, if waste rock backfilling is not properly graded and mixed, it will not only affect the stability of the backfill but may also release harmful substances such as heavy metals, causing irreversible damage to the mining area's ecological environment.

[0006] In summary, there is an urgent need to develop a comprehensive technical solution that integrates efficient mining, intelligent monitoring, reliable support, and green backfilling to achieve synergistic optimization of mining technology and roof management in the mining of gently dipping ore bodies, thereby breaking through existing technical bottlenecks. Summary of the Invention

[0007] The purpose of this invention is to provide a method for mining gently inclined ore bodies and managing the roof. By innovating mining technology, optimizing support structure, introducing intelligent monitoring technology and developing new filling materials, the method achieves synergistic efficiency in all aspects of the mining process and effectively solves a series of problems existing in the prior art.

[0008] The technical solution adopted by this invention to solve its technical problem is: a method for mining gently dipping ore bodies and managing the roof, comprising the following steps: The gently dipping ore body is divided into mining units with a layer height of 1.5-4m along the vertical direction. An intermittent skip mining sequence is adopted. An isolation pillar with a width of 3-8m is reserved between adjacent mining units. Stress relief holes with a diameter of 80-120mm and a depth of 1 / 3-2 / 3 of the pillar height are arranged in the isolation pillar. Before the mining of each mining unit, a distributed fiber optic-stress sensor hybrid monitoring network is constructed. Monitoring sections are arranged every 5-10m along the roof strike (10m for intact rock mass and 5m for fractured rock mass). Each section is equipped with 2-4 fiber optic sensors (monitoring strain distribution) and 3-5 stress sensors (focusing on the vicinity of faults and joints), forming a 'surface-point' combined monitoring network. Real-time data processing is achieved through a 5G-MEC system. A composite backfill material consisting of tailings, industrial waste, biodegradable fibers, and gel additives is used to backfill the goaf. The gel additive is prepared by mixing sodium alginate and calcium chloride at a mass ratio of 1:(0.8-1.2), and the amount added is 0.2-0.6% of the total mass of the backfill material. The particle size of tailings and industrial waste is controlled to 0.05-2mm by a vibrating screen, and the slurry concentration is controlled to 78-88%. The slope of the pumping pipeline is optimized to 3°-8° and the flow rate is 1.2-2m / s to achieve high-concentration delivery. Based on monitoring data, the roof stability assessment formula is used. Calculate the stability coefficient S (where S is the stability coefficient ... For the maximum measured stress, The ultimate strength of the rock mass For cumulative displacement, To allow displacement, For displacement rate, The critical rate, , , The weighting coefficients and , , , ; Safe zones are divided according to stability coefficients. Warning Zone Danger Zone When in the safe zone, a biodegradable fiber-reinforced support structure composed of biodegradable polylactic acid fiber with a fiber volume content of 3-8% and a metal support is used, with an overlap length of 0.4-0.6m. When in the warning zone, a truss anchor cable-grouting combined support structure with a length of 9-12m and a prestress of 150-250kN is used, with the grouting material being ultrafine cement-water glass double-liquid grout with a water-cement ratio of 0.7-1.0 and a water glass concentration of 40-45Be'. When in the dangerous zone, a concrete inverted arch-steel pipe column combined support structure with a concrete strength grade of C30-C40, a steel pipe column diameter of 200-300mm, and a wall thickness of 8-12mm is used. The impact of mining disturbances is simulated in real time using a digital twin model, and the mining sequence, backfilling parameters, and support scheme are dynamically optimized based on the roof stability assessment results.

[0009] Specifically, the stress relief holes are constructed using a spiral drilling sequence. This involves arranging the holes in a clockwise spiral pattern, with the center of the isolated pillar as the origin. The spacing between adjacent holes is 1.5-2.0m, the borehole inclination angle is 30°-45° relative to the direction of force on the pillar, and the hole depth is 1 / 3-2 / 3 of the pillar height. This process gradually releases the concentrated stress within the pillar, reducing the risk of instability.

[0010] Specifically, the inner wall of the pipe of the composite filling material is provided with a special wear-resistant coating; the inner wall of the pipe of the composite filling material is sprayed with a 0.5-1mm tungsten carbide ceramic wear-resistant coating (supersonic spraying process, hardness ≥HRC65), which extends the wear resistance life by 3-5 times.

[0011] Specifically, the data latency of the distributed fiber optic-stress sensor hybrid monitoring network is less than 200ms.

[0012] Specifically, in the truss anchor cable-grouting combined support, the anchor cable borehole diameter is 110-130mm, and the inclination angle is 10-15°; in the truss anchor cable-grouting combined support, the anchor cable borehole diameter is 110-130mm, the inclination angle is 10-15° (parallel to the principal stress direction of the top slab), and the prestress is 150-250kN; the grouting material is an ultrafine cement-water glass double-liquid grout with a water-cement ratio of 0.7-1.0, a water glass concentration of 40-45Be′, a grouting pressure of 1.0-1.5MPa, and an initial setting time of 15-30min.

[0013] Specifically, in the concrete inverted arch-steel pipe column combined support, transverse connecting steel beams are set between the steel pipe columns; in the concrete inverted arch-steel pipe column combined support, transverse connecting steel beams are set between the steel pipe columns, the steel beams are I16 I-beams, and are connected to the steel pipe columns by M20 high-strength bolts (bolt spacing ≤ 500mm), with a transverse bearing capacity ≥ 50kN / m, forming a space truss structure.

[0014] Specifically, the metal scaffold of the biodegradable fiber-reinforced scaffold is model U29-U36.

[0015] Specifically, in the composite backfilling technology, the mass ratio of tailings to industrial waste is 3:7-7:3; The preferred ratio is 5:5, in which case the compressive strength of the filling material can reach 2.5-3.0 MPa. The optimal amount of additive is 0.4%, at which point the slurry has the best fluidity and the conveying resistance is reduced by 15-20%.

[0016] Specifically, the 5G-MEC system performs edge computing on monitoring data to automatically push early warning information. The processing flow of the 5G-MEC system for edge computing monitoring data is as follows: sensor data is collected in real time through the 5G network (sampling frequency ≥10Hz), noise reduction and filtering preprocessing are performed using the edge server, early warning information is automatically generated based on preset thresholds (such as stress exceeding the ultimate strength by 80% or displacement rate >5mm / d), and pushed to the downhole terminal and the ground control center through the wireless communication module, with a data delay ≤200ms.

[0017] Specifically, the digital twin model is combined with geological exploration data to construct a three-dimensional dynamic mining model.

[0018] Specifically, the 5G-MEC system is a converged system based on 5G communication and mobile edge computing (Multi-access Edge Computing) to achieve local data processing and low-latency transmission. The digital twin model: Through three-dimensional modeling and simulation technology, a virtual model corresponding to the physical ore body is constructed to map the impact of mining disturbances in real time.

[0019] The beneficial effects of this invention are: Improving the economy and reliability of support systems: Utilizing biodegradable fiber-reinforced scaffolds and composite filling technology reduces costs by 40-60% compared to traditional metal supports, while simultaneously enhancing the deformation adaptability of the support structure and significantly reducing the risk of support failure. The use of industrial waste to prepare filling materials achieves resource recycling, further reducing filling costs.

[0020] Achieving intelligent and precise monitoring and early warning: The combination of a distributed fiber optic-stress sensor hybrid monitoring network and a 5G-MEC system enables real-time and precise monitoring of the roof condition. Through a dynamic evaluation model, the risk of roof instability can be predicted 5-7 days in advance, with an early warning accuracy rate exceeding 90%, providing strong support for safe production.

[0021] Optimizing ground pressure management and filling efficiency: Composite filling technology effectively solves the technical problems of traditional filling methods, improves the stability of slurry transportation, and increases filling efficiency by 30-45%. At the same time, this method can effectively control ground pressure, reduce surface subsidence by more than 90%, and protect the ecological environment of the mining area.

[0022] Promote synergistic efficiency in mining: Optimize mining and support operations through digital twin models, reduce downtime caused by roof problems, increase overall mine production efficiency by 35-50%, increase ore recovery rate by 12-18%, and achieve safe and efficient mining of gently dipping ore bodies. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 The flowchart illustrates the method for mining gently dipping ore bodies and managing the roof provided by this invention. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0026] like Figure 1 As shown, the method for mining gently dipping ore bodies and managing the roof according to the present invention specifically includes the following steps: Mining and Pretreatment of the Ore Body: The gently dipping ore body is divided vertically into mining units with a layer height of 1.5-4m. Based on the stability of the ore body and geological conditions, an intermittent skip-mining sequence is adopted, with isolation pillars 3-8m wide reserved between adjacent mining units. Ground-penetrating radar and other equipment are used to detect the isolation pillar areas. After identifying stress concentration points, stress relief holes with a diameter of 80-120mm and a depth of 1 / 3-2 / 3 of the pillar height are installed. A spiral drilling sequence is used to effectively release internal stress in the pillars, reduce stress concentration, and minimize the risk of pillar instability.

[0027] Real-time monitoring network construction: Before the start of mining operations in each mining unit, a distributed fiber optic-stress sensor hybrid monitoring network is constructed. A monitoring section is deployed every 5-10m along the roof strike, with 2-4 fiber optic sensors and 3-5 stress sensors installed in each section to achieve real-time monitoring of multiple parameters such as roof strain and stress. Monitoring data is transmitted and processed via a 5G-MEC system, with a data latency of less than 200ms, ensuring the timeliness and accuracy of monitoring information and providing reliable data support for roof stability assessment.

[0028] Application of composite backfill technology: After the mining operation is completed, a composite backfill material composed of tailings, industrial waste, biodegradable fibers, and gel additives is used to backfill the goaf. The gel additive is prepared by mixing sodium alginate and calcium chloride at a mass ratio of 1:(0.8-1.2), with an addition amount of 0.2-0.6% of the total mass of the backfill material. This significantly improves the fluidity and water retention of the slurry. The tailings and industrial waste are screened in three stages using a vibrating screen to control the particle size to 0.05-2mm, ensuring a reasonable gradation of the backfill material. The slurry concentration is controlled at 78-88%. Simultaneously, the slope (3°-8°) and flow velocity (1.2-2m / s) of the pumping pipeline are optimized, and a special wear-resistant coating is applied to the inner wall of the pipeline to achieve stable delivery of high-concentration slurry, avoid pipeline blockage, and improve backfilling efficiency and quality.

[0029] Dynamic assessment of roof stability: Based on data acquired by the monitoring system, and using the roof stability assessment formula... Calculate the stability coefficient S. Where, , , The weights can be dynamically adjusted according to different geological conditions. Based on the calculation results, the roof condition is divided into safe zones. Warning Zone Danger Zone This provides a basis for subsequent support decisions.

[0030] Adaptive Support Decision-Making and Implementation: Based on the roof stability assessment results, differentiated support strategies are implemented. When the roof is in the safe zone, a biodegradable fiber-reinforced support system composed of biodegradable polylactic acid fiber (fiber volume fraction 3-8%) and metal supports (model U29-U36) is used for support. The support overlap length is 0.4-0.6m. While meeting the support strength requirements, it can naturally degrade after fulfilling its support function, reducing downhole residue. When the roof is in the warning zone, a truss anchor cable-grouting combined support system is used. The anchor cable length is 9-12m, the prestress is 150-250kN, the anchor cable borehole diameter is 110-130mm, and the inclination angle is 1. For areas with a temperature range of 0-15°, the grouting material used is an ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 0.7-1.0 and a water glass concentration of 40-45Be'. Grouting reinforces the fractured rock mass and, combined with the suspension effect of anchor cables, improves the stability of the roof. When in hazardous areas, a concrete inverted arch-steel pipe column combination support is used. The concrete strength grade is C30-C40, the steel pipe column diameter is 200-300mm, and the wall thickness is 8-12mm. Transverse connecting steel beams are installed between the steel pipe columns to form a high-strength support structure, quickly control roof deformation, and ensure mining safety.

[0031] Collaborative optimization mechanism: By establishing a digital twin model and combining it with geological exploration data to construct a three-dimensional dynamic mining model, the impact of mining disturbances on the roof is simulated in real time. Based on the roof stability assessment results, the mining sequence, backfilling parameters, and support scheme are dynamically optimized. The mining time and support intensity of subsequent mining units are adjusted in advance, realizing coordinated operation of mining technology and roof management, effectively improving mining efficiency and safety.

[0032] Example 1 Project Overview: A coal mine has a gently dipping coal seam with a dip angle of 12° and an average thickness of 5m. It is a typical "three-soft" stratum, with mudstone as the roof and claystone as the floor. The coal seam is soft and broken, with a uniaxial compressive strength of only 1.2MPa. Moreover, the water pressure of the aquifer in the roof reaches 0.8MPa, making the mining conditions extremely complex. Roof collapse and spalling accidents are very likely to occur.

[0033] Specific implementation steps Mining and Pre-treatment of the Ore Body: The coal seam was divided into three stratified mining units vertically, with a stratification height of 1.5m. An intermittent skip-mining sequence was adopted, with priority given to mining units 1 and 3. A 3m wide isolation pillar was reserved between adjacent mining units. Ground-penetrating radar was used to conduct detailed surveys of the isolation pillar areas to identify stress concentration zones, and stress relief holes were then installed. These stress relief holes had a diameter of 80mm and a depth of 1m (one-third of the pillar height), and were constructed using a spiral drilling sequence. A total of 30 stress relief holes were installed, effectively releasing internal stress within the pillar and reducing the risk of pillar instability.

[0034] Real-time monitoring network construction: Before the retreat of each mining unit, a monitoring section is set up every 5m along the roof strike. Each section is equipped with 2 fiber optic sensors and 3 stress sensors. The fiber optic sensors are fiber optic grating strain sensors, and the stress sensors are vibrating wire stress sensors. The sensors are connected to the underground 5G base station via armored optical cables. The data is processed by the 5G-MEC (Mobile Edge Computing) system and transmitted to the ground control center with a delay of less than 200ms. The ground control center uses professional data analysis software to perform real-time analysis and visualization of the roof strain and stress data, generating a data report every 5 minutes.

[0035] Application of composite backfilling technology: The backfill material is a mixture of tailings and fly ash at a mass ratio of 6:4, with the addition of 0.2% gelling additive (sodium alginate to calcium chloride mass ratio of 1:0.8) and 3% biodegradable polylactic acid fiber by volume. The tailings and fly ash are screened three times using a vibrating screen to control the particle size between 0.05-2mm, and then stirred to produce a high-flowability backfill with a slurry concentration of 78% and a slump of 200mm. A dedicated double-cylinder piston-type backfilling pump is used, transported through a wear-resistant pipe with an inner diameter of 150mm. The pumping pipeline slope is optimized to 3°, and the flow rate is controlled at 1.2m / s. A slurry concentration detector is installed at the pipeline inlet to monitor and adjust the slurry ratio in real time; a flow control valve is installed at the pipeline outlet to adjust the slurry flow rate in real time according to the backfilling progress. The entire backfilling process lasts 12 hours, filling a goaf volume of 1800m³.

[0036] Dynamic assessment of roof stability: The roof stability assessment formula is adopted. Calculations were performed. The maximum stress measured at a certain monitoring section during mining operations was... The ultimate strength of the rock mass was determined through indoor tests. Cumulative displacement Permissible displacement displacement rate Critical rate Substituting into the formula, we get: The area was determined to be a danger zone.

[0037] Adaptive Support Decision-Making and Implementation: For the hazardous area, a combined concrete inverted arch and steel pipe column support system was immediately adopted. First, the concrete inverted arch was constructed using C35 concrete, with a pouring thickness of 300mm. Custom-made formwork was used for on-site pouring to ensure the inverted arch shape met design requirements. Then, steel pipe columns were installed. These columns had a diameter of 250mm, a wall thickness of 10mm, and were spaced 1.5m apart. Transverse connecting steel beams, made of I16 I-beams, were installed between the columns and welded to the steel pipe columns. Simultaneously, the roof was reinforced with full-section grouting. The grouting material was ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 0.8, a water glass concentration of 42Be', and a grouting pressure of 1.0-1.5MPa. A total of 40 grouting holes were constructed, effectively controlling roof deformation. Collaborative Optimization Mechanism: Real-time simulation of the mining process using a digital twin model revealed that when the planned mining speed of 2m per day was maintained, the roof deformation rate accelerated. Based on the simulation results, the mining speed was adjusted to 1.5 m / d, and the support parameters of subsequent mining units were optimized in advance, increasing the fiber volume content of the biodegradable fiber-reinforced support to 5%. After optimization, roof deformation was effectively controlled, no major roof accidents occurred during the entire mining process, the ore recovery rate reached 88%, the filling efficiency was improved by 32% compared with the traditional method, and the support cost was reduced by 45%.

[0038] Example 2 Project Overview: A copper mine has a gently dipping ore body with a dip angle of 20° and an average thickness of 8m. The ore body passes through three faults, the rock mass is severely fractured with well-developed fissures, and the groundwater flow rate reaches 5m³ / h. The uniaxial compressive strength of the rock varies greatly, only 8MPa near the faults and 25MPa in normal areas. During mining, the roof is highly susceptible to collapse along the faults and fissures, and the groundwater has a significant impact on the performance of the backfill materials.

[0039] Specific implementation steps Mining and Pretreatment of the Ore Body: The ore body was divided into four layered mining units, each 2m high, using an intermittent skip-mining sequence. A 5m wide isolation pillar was reserved between adjacent units. Before constructing the isolation pillars, curtain grouting was used to reinforce the surrounding rock mass. The grouting material was a cement-water glass dual-liquid grout with a water-cement ratio of 1:1, a water glass concentration of 38Be', and a grouting pressure of 0.6-1.0MPa. A total of 60 grouting holes were constructed to form a closed curtain wall. Then, stress relief holes were installed, with a diameter of 100mm and a depth of 3m (3 / 5 of the pillar height). A spiral drilling sequence was used, with a spacing of 1.5m between stress relief holes.

[0040] Real-time monitoring network construction: The monitoring cross-section spacing is set at 7m, with 3 fiber optic sensors and 4 stress sensors installed at each cross-section. The fiber optic sensors are used to monitor the strain distribution of the roof, while the stress sensors focus on monitoring stress changes near the fault. All sensor data is transmitted to the ground control center via a 5G network. The ground control center establishes a roof monitoring database, uses machine learning algorithms to analyze historical data, builds a roof deformation prediction model, and updates the prediction results hourly.

[0041] Application of composite backfill technology: The backfill material is a 5:5 mass ratio mixture of tailings and slag, with 0.4% gel additive (sodium alginate and calcium chloride in a 1:1 mass ratio) and 5% biodegradable fiber volume content. Considering the impact of groundwater, the water resistance of the backfill material is optimized by adding an appropriate amount of waterproofing agent. The slurry particle size is controlled at 0.05-2mm using a vibrating screen to produce a backfill body with a slurry concentration of 82% and a spread of 220mm. When the conveying distance is 100m, the pumping pipeline slope is adjusted to 5°, the flow rate is controlled at 1.5m / s, and the pumping pressure is calculated using a formula. Pressure sensors were installed every 20 meters along the pipeline to monitor pressure changes in real time and ensure the smooth progress of the filling work. In the area near the fault, a localized densification filling method was adopted, with the filling thickness in the densified area increased by 0.5 meters.

[0042] Dynamic assessment of roof stability: The roof stability assessment formula is adopted, taking... , , During the mining process in a certain monitoring area, the maximum stress was measured. ultimate strength of rock mass (Near the fault) Cumulative displacement Permissible displacement displacement rate Critical rate The stability coefficient was calculated. The area was designated as a warning zone.

[0043] Adaptive Support Decision-Making and Implementation: For the warning zone, a combined truss anchor cable-grouting support system was adopted. The anchor cables were 10m long, with a prestress of 180kN, an anchor cable borehole diameter of 130mm, and an inclination angle of 15°, totaling 25 anchor cables. The grouting material was ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 0.9, a water glass concentration of 43Be', and a grouting pressure of 1.2-1.6MPa. Grouting was performed through the anchor cable boreholes to reinforce the fractured rock mass. Simultaneously, a steel mesh with specifications of Φ6@200×200 was laid on the top slab surface and connected to the truss anchor cables to form an integrated support structure.

[0044] Collaborative optimization mechanism: Real-time simulation using a digital twin model revealed significant stress concentration in the roof during mining near the fault. Based on the simulation results, the mining sequence was adjusted, first reinforcing the areas on both sides of the fault before mining the central area. Simultaneously, the filling parameters were optimized, increasing the ash-sand ratio of the filling material near the fault to 1:8. After optimization, roof deformation was effectively controlled, preventing roof collapse accidents, achieving an 85% ore recovery rate, increasing filling efficiency by 35%, and reducing support costs by 48%.

[0045] Example 3 Project Overview: A gently dipping iron ore body with a dip angle of 18° and an average thickness of 6m is located in a mine. The roof is composed of hard quartz sandstone, but it contains numerous joints and fissures with a joint spacing of approximately 0.5m. Many of these are open fractures with a width of 2-5mm. The uniaxial compressive strength of the rock reaches 80MPa, but it is highly susceptible to block falls and localized collapses under mining disturbances. Furthermore, the mining area is located beneath surface structures, necessitating strict control over surface subsidence.

[0046] Specific implementation steps Ore body mining and pretreatment: The stratification height was set at 1.8m, dividing the area into 3 mining units, with isolation pillars 4m wide. A total station was used for precise layout of the pillars. A hydraulic drilling rig was used to construct stress relief holes, with a diameter of 90mm and a depth of 2.4m (3 / 5 of the pillar height), spaced 1.3m apart, for a total of 24 stress relief holes. During construction, the drilling angle and depth were strictly controlled to ensure the quality of the stress relief holes.

[0047] Real-time monitoring network construction: Monitoring sections are spaced 6m apart, with 2 fiber optic sensors and 3 stress sensors installed at each section. A 3D visualization monitoring platform is set up at the ground control center to display the monitoring data in real time on a 3D model, intuitively showing the stress and strain distribution of the roof slab. Simultaneously, an audible and visual alarm device is installed to promptly issue an alarm when the roof slab data exceeds the warning threshold.

[0048] Composite backfilling technology application: The backfill material contains tailings and steel slag in a 7:3 mass ratio, with 0.3% gel additive (sodium alginate to calcium chloride in a 1:0.9 mass ratio) and 4% biodegradable fiber volume content. The particle size is controlled at 0.05-2mm using a vibrating screen to produce a backfill with an 80% slurry concentration and a consistency of 180mm. When the conveying distance is 80m, the pumping pressure is calculated according to the formula. Wear-resistant elbows are installed at pipe bends, and pipe expansion joints are installed every 30m to reduce pipe wear and stress concentration. Before backfilling, the goaf is cleaned with high-pressure air at a speed of 15m / s for 20 minutes to ensure cleanliness and improve the bonding between the backfill and the roof. The entire backfilling process adopts a layered and staged backfilling technique, with each layer controlled to a thickness of 0.6m. The next layer is filled only after the lower layer has initially set.

[0049] Dynamic assessment of roof stability: The roof stability assessment formula is adopted, taking... , , During the mining process in a certain monitoring area, the maximum stress was measured. ultimate strength of rock mass Cumulative displacement Permissible displacement displacement rate Critical rate The stability coefficient was calculated. The area was designated as a warning zone.

[0050] Adaptive Support Decision-Making and Implementation: For the warning zone, a combined truss anchor cable-grouting support system was adopted. The anchor cables were 11m long, with a prestress of 200kN, and a total of 20 anchor cables were installed. The grouting material was ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 1.0, a water glass concentration of 45Be', and a grouting pressure of 1.3-1.7MPa. Simultaneously, in areas with well-developed joints, anchor bolts with mesh and shotcrete were used for support. The anchor bolts were 2m long, 22mm in diameter, spaced 1m apart in a quincunx pattern, and reinforced with Φ8@250×250 steel mesh. C25 concrete was then sprayed to a thickness of 80mm.

[0051] Collaborative optimization mechanism: Digital twin model simulations showed that localized surface subsidence might occur as mining progressed. Based on the simulation results, the backfilling scheme was adjusted, increasing the strength of the backfill material near the surface and raising the ash-sand ratio to 1:6. Simultaneously, the mining speed was optimized, increasing the daily mining rate from 2 m / d to 1.8 m / d. After optimization, surface subsidence was effectively controlled, with the maximum subsidence limited to within 15 mm, without impacting surface structures. The ore recovery rate reached 87%, backfilling efficiency improved by 33%, and support costs decreased by 50%.

[0052] Example 4 Project Overview: A lead-zinc mine has a gently dipping ore body with a dip angle of 15° and an average thickness of 7m. The rock mass has a fractured structure and contains weak interlayers with a thickness of 0.2-0.5m. The mechanical properties are extremely poor, with a uniaxial compressive strength of only 3MPa. Moreover, the mining area is located on the edge of a water source protection area, so the environmental protection and seepage prevention requirements for the backfill material are extremely high.

[0053] Specific implementation steps Mining and Pretreatment of the Ore Body: The ore body was divided into four layered mining units, each 1.8m high, with isolation pillars 6m wide. Before constructing the isolation pillars, the pillar area was thoroughly surveyed using ground-penetrating radar and borehole inspection equipment to determine the location of weak interlayers. Then, sleeve valve grouting technology was used to reinforce the weak interlayers. The grouting material was a cement-water glass dual-liquid grout with a water-cement ratio of 1.2:1, a water glass concentration of 35Be', and a grouting pressure of 0.8-1.2MPa. After reinforcement, stress relief holes were installed, with a diameter of 110mm, a depth of 3.6m (3 / 5 of the pillar height), and a spacing of 1.8m between holes.

[0054] Real-time monitoring network construction: Monitoring sections are spaced 8m apart, with 3 fiber optic sensors and 4 stress sensors installed at each section. An environmental monitoring subsystem is established to monitor groundwater quality and surface displacement in real time. Multiple water quality monitoring points are set up around the filling area, monitoring indicators including heavy metal content and pH, with data collected every 2 hours.

[0055] Composite backfilling technology application: The backfill material is a mixture of tailings and industrial waste (phosphogypsum) in a 4:6 mass ratio, with the addition of 0.5% environmentally friendly gel additive (made from natural plant colloids) and 6% biodegradable fiber volume content. The particle size is controlled at 0.05-2mm using a vibrating screen to produce a backfill with a slurry concentration of 85% and a flowability of 210mm. Before backfilling, the backfill material is tested for heavy metal content to ensure compliance with environmental standards. At a conveying distance of 90m, the pumping pipeline slope is adjusted to 6°, the flow rate is 1.6m / s, and the calculated pumping pressure is... A flow control valve is installed at the pipeline outlet to adjust the slurry flow rate in real time according to the filling progress. Simultaneously, a layer of impermeable geomembrane is laid in the area where the filling material contacts groundwater to prevent harmful substances in the filling material from seeping into the groundwater.

[0056] Dynamic assessment of roof stability: The roof stability assessment formula is adopted, taking... , During the mining process in a certain monitoring area, the maximum stress was measured. ultimate strength of rock mass (weak interlayer), cumulative displacement Permissible displacement displacement rate Critical rate The stability coefficient was calculated. The area was designated as a warning zone.

[0057] Adaptive Support Decision-Making and Implementation: For the warning zone, a combined truss anchor cable-grouting support system was adopted. The anchor cables were 9m long, with a prestress of 160kN, and a total of 22 anchor cables were installed. The grouting material was ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 0.8, a water glass concentration of 42Be', and a grouting pressure of 1.1-1.5MPa. Simultaneously, steel strips (400mm x 5mm) were installed at the weak interlayer locations to connect the anchor cables and steel strips, forming an integrated support structure and enhancing control over the weak interlayer.

[0058] Collaborative optimization mechanism: Digital twin model simulations showed significant roof deformation during mining near weak interlayers. Based on the simulation results, the mining sequence was adjusted, first reinforcing the areas above and below the weak interlayers with filler material, then mining the weak interlayer area. Simultaneously, filler parameters were optimized, increasing the ash-sand ratio of the filler in the weak interlayer area to 1:7 and increasing the biodegradable fiber content to 8%. During mining, groundwater quality changes were closely monitored, and environmental protection measures were adjusted promptly based on monitoring data. After optimization, roof deformation was effectively controlled, no roof collapse accidents occurred, groundwater quality was not significantly polluted, ore recovery rate reached 86%, filler efficiency increased by 38%, and support costs decreased by 42%.

[0059] Example 5 Project Overview: A manganese mine has a gently dipping ore body with a dip angle of 25°, an average thickness of 10m, and a burial depth of up to 800m. The ground stress reaches 25MPa, classifying it as a high-stress mining environment. The rock mass has generally good integrity, with multiple gently dipping joints. The friction coefficient of the joint surfaces is only 0.3, making the roof highly susceptible to sliding and instability along these joint surfaces during mining. Furthermore, there is a vital transportation artery above the mining area, necessitating strict control over surface deformation.

[0060] Specific implementation steps Ore body mining and pretreatment: The ore body was divided into four mining units with a layer height of 2.5m and an isolation pillar width of 7m. High-precision modeling of the pillars was performed using 3D laser scanning technology to accurately determine stress concentration areas and joint distribution. Based on the modeling results, stress relief holes were installed with a diameter of 120mm and a depth of 4.2m (3 / 5 of the pillar height), spaced 2m apart. Mechanical rotary drilling equipment was used to ensure drilling accuracy. A total of 35 stress relief holes were constructed, effectively reducing stress concentration in the pillars.

[0061] Real-time monitoring network construction: Monitoring sections are spaced 10m apart, with 4 fiber optic sensors and 5 stress sensors installed at each section, increasing the data sampling frequency to 5 times per minute. A roof monitoring cloud platform is established to enable data sharing and collaborative analysis among multiple departments. A dedicated early warning center is set up at the ground control center, staffed with professional personnel on duty 24 hours a day. When monitoring data exceeds the warning value, the emergency plan is immediately activated.

[0062] Composite backfilling technology application: The backfill material is a mixture of tailings and industrial waste (coal gangue) at a mass ratio of 3:7, with the addition of 0.6% gel additive (sodium alginate to calcium chloride mass ratio of 1:1.2) and 8% biodegradable fiber volume content. The particle size is controlled at 0.05-2mm using a vibrating screen to produce a high-concentration backfill with a slurry concentration of 88% and a slump drop time of 18s. For a conveying distance of 120m, the pumping pipeline slope is adjusted to 8°, the flow rate is controlled at 2m / s, and the calculated pumping pressure is... A flow control valve is installed at the pipeline outlet to adjust the slurry flow rate in real time according to the filling progress. Simultaneously, an appropriate amount of early-strength agent is added to the filling material to improve its early strength and better control roof deformation.

[0063] Dynamic assessment of roof stability: The roof stability assessment formula is adopted, taking... , , During the mining process in a certain monitoring area, the maximum stress was measured. ultimate strength of rock mass Cumulative displacement Permissible displacement displacement rate Critical rate The stability coefficient was calculated. The area was designated as a warning zone.

[0064] Adaptive Support Decision-Making and Implementation: For the warning zone, a combined truss anchor cable-grouting support system was adopted. The anchor cables were 12m long, with a prestress of 250kN, and a total of 30 anchor cables were installed. The grouting material was ultrafine cement-water glass dual-liquid grout with a water-cement ratio of 1.0, a water glass concentration of 45Be', and a grouting pressure of 1.5-2.0MPa. Simultaneously, a steel mesh with specifications of Φ10@200×200 was laid on the top slab surface and connected to the truss anchor cables to form an integral support structure. Furthermore, chemical grouting was used at the joint surfaces, injecting epoxy resin adhesive to increase the friction coefficient of the joint surfaces and enhance the stability of the top slab.

[0065] Collaborative optimization mechanism: Digital twin model simulations showed that roof deformation and surface subsidence risks were significant during mining in high-stress areas. Based on the simulation results, the mining sequence was adjusted, adopting a segmented mining and intermittent backfilling approach to reduce the impact of mining disturbance on the roof. Simultaneously, backfilling parameters were optimized, increasing the elastic modulus of the backfill and adjusting the lime-sand ratio to 1:6. During mining, surface deformation was monitored in real time, and support measures were adjusted promptly based on the monitoring data. After optimization, roof deformation and surface subsidence were effectively controlled, with the maximum surface subsidence kept below 20mm, without impacting main traffic arteries. The ore recovery rate reached 84%, backfilling efficiency increased by 40%, and support costs decreased by 40%.

[0066] Example 6 Project Overview: A gold mine features a gently dipping ore body with a dip angle of 10° and an average thickness of 4m. Located below a water source protection area, the ore body has extremely high environmental protection requirements. The rock mass is mainly gneiss with a small number of fracture zones. The groundwater quality is sensitive, and strict requirements are placed on the environmental friendliness and stability of the backfill materials.

[0067] Specific implementation steps Ore body mining and pretreatment: The mining was divided into two layered mining units, with a layer height of 2m and an isolation pillar width of 3m. During pillar construction, low-vibration drilling equipment was used to construct stress relief holes with a diameter of 80mm, a depth of 1m (1 / 3 of the pillar height), and a hole spacing of 1m to minimize disturbance to the surrounding rock mass. A total of 15 stress relief holes were constructed.

[0068] Real-time monitoring network construction: Monitoring sections are spaced 5m apart, with 2 fiber optic sensors and 3 stress sensors installed at each section. Data is uploaded to the ground control center via a wireless transmission module. An environmental monitoring subsystem is established to monitor groundwater quality and surface subsidence in real time. Multiple water quality monitoring points are set up at the boundary of the water source protection area, and multiple surface subsidence monitoring points are set up above the ore body, collecting data hourly.

[0069] Composite backfilling technology application: The backfill material is a 5:5 mass ratio mixture of tailings and industrial waste (desulfurized gypsum), with 0.2% environmentally friendly gel additive (made from natural plant colloids) added, and 3% biodegradable fiber volume fraction. The particle size is controlled at 0.05-2mm using a vibrating screen, resulting in an environmentally friendly backfill with a slurry concentration of 78% and a pH of 7.5. A closed pipeline transportation system is used during transportation to prevent slurry leakage and environmental pollution. Before backfilling, the backfill material undergoes heavy metal and radioactivity testing to ensure compliance with environmental standards. A flow control valve is installed at the pipeline outlet to adjust the slurry flow rate in real time according to the backfilling progress. Simultaneously, an anti-seepage curtain is installed around the goaf area, using cement-bentonite grout with a permeability coefficient less than [missing value]. This is to prevent harmful substances in the backfill from seeping into the groundwater.

[0070] Dynamic assessment of roof stability: The roof stability assessment formula is adopted, taking... , , During the mining process in a certain monitoring area, the maximum stress was measured. ultimate strength of rock mass Cumulative displacement Permissible displacement displacement rate Critical rate The stability coefficient was calculated. The area was determined to be a safe zone.

[0071] Adaptive Support Decision-Making and Implementation: For the safety zone, biodegradable fiber-reinforced support is used. The support is composed of biodegradable polylactic acid fiber and U29 steel support, with a fiber volume fraction of 3% and a support overlap length of 0.4m. Biodegradable materials are laminated onto the support surface, allowing it to decompose naturally after the support task is completed, avoiding residual pollution downhole.

[0072] Collaborative optimization mechanism: Digital twin model simulations revealed potential risks to groundwater quality during mining operations beneath a water source protection area. Based on the simulation results, the backfilling scheme was adjusted. The thickness of the anti-seepage curtain was increased in areas near the water source protection area, and adsorbents were added to the backfill to absorb potentially leaked hazardous substances. Simultaneously, the mining speed was optimized from 1.5 m / day to 1.2 m / day. During mining, changes in groundwater quality were closely monitored, and environmental protection measures were adjusted promptly based on monitoring data. After optimization, groundwater quality was effectively protected, no water pollution incidents occurred, the ore recovery rate reached 85%, backfilling efficiency increased by 30%, and support costs decreased by 55%.

[0073] Example 7 Project Overview: A gently dipping iron ore body with a dip angle of 15° and an average thickness of 12m is divided into three layered mining units, each layer 4m high. Isolation pillars are 8m wide, and stress relief holes have a diameter of 120mm and a depth of 2.7m (1 / 3 of the pillar height). The backfill material is tailings:industrial waste = 7:3, with a slurry concentration of 88% and a pumping velocity of 2m / s. C40 concrete inverted arch support with Φ300mm×12mm steel pipe columns is used. The roof stability coefficient S = 0.58 (danger zone). After support, surface settlement is ≤25mm, backfilling efficiency is increased by 45%, and support costs are reduced by 40%.

[0074] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for mining gently dipping ore bodies and managing the roof, characterized in that, Includes the following steps: The gently dipping ore body is divided into mining units with a layer height of 1.5-4m along the vertical direction. An intermittent skip mining sequence is adopted. An isolation pillar with a width of 3-8m is reserved between adjacent mining units. Stress relief holes with a diameter of 80-120mm and a depth of 1 / 3-2 / 3 of the pillar height are arranged in the isolation pillar. Before the mining of each mining unit, a distributed fiber optic-stress sensor hybrid monitoring network is constructed. Monitoring sections are arranged every 5-10m along the roof strike, with 2-4 fiber optic sensors and 3-5 stress sensors arranged in each section. Data is processed in real time through a 5G-MEC system. A composite backfill material consisting of tailings, industrial waste, biodegradable fibers, and gel additives is used to backfill the goaf. The gel additive is prepared by mixing sodium alginate and calcium chloride at a mass ratio of 1:(0.8-1.2), and the amount added is 0.2-0.6% of the total mass of the backfill material. The particle size of tailings and industrial waste is controlled to 0.05-2mm by a vibrating screen, and the slurry concentration is controlled to 78-88%. The slope of the pumping pipeline is optimized to 3°-8° and the flow rate is 1.2-2m / s to achieve high-concentration delivery. Based on monitoring data, the roof stability assessment formula is used. Calculate the stability coefficient S (where S is the stability coefficient ... For the maximum measured stress, The ultimate strength of the rock mass For cumulative displacement, To allow displacement, For displacement rate, The critical rate, , , The weighting coefficients and , , , ; Safe zones are divided according to stability coefficients. Warning Zone Danger Zone When in the safe zone, a biodegradable fiber-reinforced support structure composed of biodegradable polylactic acid fiber with a fiber volume content of 3-8% and a metal support is used, with an overlap length of 0.4-0.6m. When in the warning zone, a truss anchor cable-grouting combined support structure with a length of 9-12m and a prestress of 150-250kN is used, with the grouting material being ultrafine cement-water glass double-liquid grout with a water-cement ratio of 0.7-1.0 and a water glass concentration of 40-45Be'. When in the dangerous zone, a concrete inverted arch-steel pipe column combined support structure with a concrete strength grade of C30-C40, a steel pipe column diameter of 200-300mm, and a wall thickness of 8-12mm is used. The impact of mining disturbances is simulated in real time using a digital twin model, and the mining sequence, backfilling parameters, and support scheme are dynamically optimized based on the roof stability assessment results.

2. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The stress relief holes were constructed using a spiral drilling sequence.

3. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The inner wall of the pipe is coated with a special wear-resistant coating.

4. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The data latency of the distributed fiber optic-stress sensor hybrid monitoring network is less than 200ms.

5. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: In the truss anchor cable-grouting combined support, the diameter of the anchor cable borehole is 110-130mm and the inclination angle is 10-15°.

6. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: In the concrete inverted arch-steel pipe column combined support, transverse connecting steel beams are set between the steel pipe columns.

7. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The metal scaffold of the biodegradable fiber-reinforced scaffold is model U29-U36.

8. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: In the composite backfilling technology, the mass ratio of tailings to industrial waste is 3:7-7:

3.

9. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The 5G-MEC system performs edge computing on monitoring data to enable automatic push of early warning information.

10. The method for mining gently dipping ore bodies and managing the roof according to claim 1, characterized in that: The digital twin model, combined with geological exploration data, constructs a three-dimensional dynamic mining model.

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