Room-pillar method pillar protective stoping method for medium-deep gently-inclined thin ore body

Abstract

The invention provides a room-and-pillar-method pillar protective stoping method for a medium-deep gently-inclined thin ore body, which comprises the following steps of: S1, constructing an initial pillar system with ground pressure buffering capability, calculating and arranging initial pillars with size surplus at the initial stage of ore body mining, and establishing an elastic core area by using the size surplus to cope with the initial surrounding rock stress; s2, a monitoring mechanism for damage evolution of the surface layer of the ore pillar is established, and physical form change data and internal stress data of the surface layer of the ore pillar are collected in real time in the recovery process; s3, executing stress release triggering judgment based on a damage threshold value, calculating the bearing state of the ore pillar according to the monitoring data, and when it is judged that the surface layer of the ore pillar completes energy absorption and does not have deep damage, generating a finishing instruction; and S4, non-blasting type precise stripping stoping operation is implemented, a finishing instruction is responded, a damaged part of the surface layer of the ore pillar is removed through a mechanical cutting means, the initial ore pillar is adjusted to the final design size, and ore resources are recycled while the high stress of the surface layer is released.

Description

Technical Field

[0001] This invention relates to the field of mining, and in particular to a room-and-pillar method for protective mining of medium-deep, gently dipping thin ore bodies. Background Technology

[0002] In the mining of gently dipping thin ore bodies at medium to deep depths, the room-and-pillar method is widely used due to its mature technology and strong adaptability. However, with increasing mining depth, the ground pressure environment becomes increasingly complex, exhibiting significant rheological characteristics. Existing technical solutions mainly focus on the static design of stope and pillar structures or rely on infill support.

[0003] Existing technology CN105298492B discloses a room-and-pillar mining method for mining gently dipping thin ore bodies. This method divides the ore block into long strip pillars of two different widths to cope with roof pressure. However, once the pillar size is determined, it is not adjusted and cannot adapt to the dynamic evolution of ground pressure over time, which can easily lead to resource waste or insufficient support in the later stages. Existing technology CN116856998A proposes a method for efficient mining using the room-and-pillar method. Although it adopts an alternating mining scheme of one pillar at a time combined with backfilling, its core still relies on the support of the backfill body for the surrounding rock. The process cost is high and does not involve the dynamic optimization of the pillar body itself. Existing technology CN120798326A involves a two-step method for shallow-hole ore extraction with pillars, followed by backfilling. While this method reduces the risk of stress superposition through sequential mining, it relies heavily on complex preparatory work and backfilling operations, failing to resolve the contradiction between stress concentration within the pillar and resource recovery. Furthermore, while existing technology CN120487094A mentions three-dimensional block division and dynamic support for medium-thick ore bodies, its ore extraction method still includes blasting techniques such as pre-splitting blasting. In deep, high-stress environments, this can easily cause vibration damage to the elastic core of the pillar, inducing sudden instability. Overall, existing technologies generally lack a dynamic control method that can utilize the pillar surface as a "stress buffer sacrificial layer" and precisely adjust it within a specific time window using non-blasting methods to achieve ground pressure management and maximize resource recovery. Summary of the Invention

[0004] The main objective of this invention is to provide a room-and-pillar method for protective pillar mining of medium-deep, gently dipping thin ore bodies. This method solves the technical problems of existing room-and-pillar methods for mining medium-deep, gently dipping thin ore bodies, where the static pillar design cannot adapt to the deep ground pressure and rheological characteristics, resulting in excessive pillar size and resource waste. It also addresses the issues of traditional blasting and trimming methods causing cumulative damage to the core of high-stress pillars, thus inducing instability.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this invention is: a room-and-pillar method for protective mining of medium-deep, gently dipping thin ore bodies. This protective mining method establishes a dynamic balance system between initial surplus support and subsequent stress release, and includes the following steps: S1: Construct an initial pillar system with ground pressure buffering capacity. Calculate and deploy initial pillars with size surplus in the early stage of ore body mining. Use this size surplus to establish an elastic core zone to cope with the initial surrounding rock stress. S2: Establish a monitoring mechanism for the surface damage evolution of the pillar, and collect data on the physical morphological changes and internal stress of the pillar surface in real time during the mining process; S3: Execute stress release trigger judgment based on damage threshold, calculate the bearing state of the pillar according to monitoring data, and generate a repair command when it is determined that the surface of the pillar has completed energy absorption and no deep damage has occurred. S4: Implement non-blasting precision stripping and mining operations, respond to adjustment instructions, use mechanical cutting methods to remove the damaged parts of the pillar surface, adjust the initial pillar to the final design size, and recover ore resources while releasing the high stress on the surface.

[0006] In the preferred scheme, in step S1, to achieve the long-term stability of the pillar under rheological pressure conditions, a derivation logic based on Protodyakonov's pressure arch theory combined with rheological surplus correction is used to determine the initial pillar side length. First, the physical and mechanical parameters of the ore and rock are obtained through on-site drilling and sampling. Then, the theoretical minimum width required to prevent shear failure of the roof is calculated. Based on this, a rheological surplus coefficient is introduced to compensate for the strength decay caused by the time effect. The specific calculation formula is as follows: ; In the formula Represents the span of the mine, This represents the average unit weight of the overlying rock strata. Represents burial depth. Represents the ultimate bearing strength of the pillar. Represents the design recovery rate; the rheological surplus coefficient introduced in the formula The calculation model used to quantify the long-term weakening effect of geological structures on ore pillars is as follows: ; in For vertical ground stress, The uniaxial compressive strength of the ore and rock. As a correction factor for the influence of on-site geological structures, the above-mentioned rheological surplus coefficient is used. The formula calculation ensures that the initial pillar has sufficient elastic core expansion space in the early stage of mining disturbance.

[0007] In the preferred embodiment, the monitoring mechanism in step S2 employs a non-contact multi-dimensional monitoring network, including an array of high-definition industrial cameras and laser scanners arranged around the pillar, using image recognition technology to capture and calculate the spalling depth on the pillar surface in real time. and surface crack development density Simultaneously, the peak value of the core vertical stress is obtained by combining the vibrating wire stress gauge pre-embedded in the center of the mine pillar, and all the above data are transmitted to the ground central processing terminal in real time for time-series analysis.

[0008] In the preferred scheme, in step S3, to accurately identify the optimal time for pillar trimming, a joint criterion function based on surface damage stripping degree and fracture convergence is constructed. A comparison algorithm is continuously run through the central processing terminal, and a trimming command is triggered only when the monitoring data simultaneously satisfy the following inequality conditions: ; In the formula, This represents the depth of spalling on the surface of the pillar monitored in step S2. This represents the initial pillar side length determined in step S2. This represents the preset surface damage and peeling threshold, which is set to a value between 0.05 and 0.15. This represents the surface crack development density monitored in step S2. Represents the monitoring time. This represents the rate of change of fracture density over time. This step, through the above mathematical criteria, strictly locks in the only time window when the surface of the pillar is sufficiently damaged and the fracture development tends to be stable, avoiding the risk of premature repair during the stress active period leading to secondary expansion of newly formed fractures into the core area.

[0009] In the preferred embodiment, the non-explosive precision stripping and mining operation in step S4 adopts a symmetrical layered cutting process. This process divides the height of the pillar to be stripped into multiple horizontal cutting layers. For each horizontal cutting layer, the excavation equipment performs ring cutting along the circumferential tangential direction of the pillar and controls the depth of a single cut to not exceed 0.5 meters, so as to avoid sudden changes in the core stress of the pillar due to instantaneous large-volume unloading.

[0010] In the preferred embodiment, the excavating equipment used in the non-blasting precision stripping and mining operation is equipped with a laser ranging and guidance system. This system establishes a three-dimensional spatial coordinate system during the operation, monitors and provides feedback on the position information of the cutting head in real time, and automatically adjusts the trajectory of the robotic arm to control the deviation between the geometric center of the cut pillar and the initial geometric center of the pillar. The following conditions must be met: ; in To ensure the final design dimensions after stripping, high-precision geometric center control is used to prevent eccentric structures in the pillars caused by human error, thereby avoiding asymmetric instability of the roof induced by additional eccentric torque.

[0011] In the preferred embodiment, the protective mining method further includes a step of quantitatively assessing the incremental resource recovery. This involves collecting, weighing, and converting the ore fragments removed by physical cutting in step S4, whereby the volume of the recovered pillar surface ore is calculated. Calculate using the following volume integral formula: ; In the formula, This represents the volume of the surface ore from the recovered pillar. This represents the total number of pillars that have undergone secondary stripping within the mining area. The index representing the number of the ore pillar. Represents the height of the pillar. Representing the The initial design side length of each pillar, Representing the The final design side length of each pillar after stripping; this step incorporates the dynamically adjusted resource increment into the mine's economic benefit evaluation system, achieving effective recovery of protective layer resources discarded by traditional processes.

[0012] In the preferred embodiment, after step S4 is completed, a secondary verification step of the pillar stability is also included. Specifically, after the physical stripping is completed, the repaired pillar is continuously monitored for 24-32 hours using microseismic monitoring equipment to capture acoustic emission signals generated by micro-fractures inside the rock mass in real time. If the energy level of the monitored microseismic event is lower than the preset safety background value, the mining operation is determined to be completed; otherwise, the pillar core is determined to be damaged, and an emergency plan must be immediately activated to reinforce the pillar with local anchor bolts.

[0013] In the preferred embodiment, this protective mining method is suitable for medium-deep mining geological environments where the roof rock mass quality score RMR value is between 50 and 70 and the ore body dip angle is between 5 and 20 degrees. This method also establishes a geological adaptability feedback adjustment mechanism. When the RMR value of the roof rock mass quality score is monitored to be lower than 50 during the mining process, the system automatically feeds back and adjusts the rheological surplus coefficient in step S1. The area is increased by 20% to compensate for the stability risk caused by the decline in the quality of the roof rock mass by increasing the initial support area.

[0014] In the preferred embodiment, the mechanical cutting method used in step S4 is a hydraulic excavator with a rotary milling head. The hydraulic excavator uses high-speed rotating cutting teeth to grind and crush the ore and rock, and has the ability to perform three-dimensional free-degree cutting operations in a confined space. Moreover, the entire cutting process completely eliminates explosive blasting, thereby completely eliminating the cumulative damage caused by blasting shock waves to the elastic core area of ​​the ore pillar that has already been subjected to high stress.

[0015] This invention provides a room-and-pillar method for protective pillar mining in medium-deep, gently dipping thin ore bodies. By constructing a dynamic balance system between initial surplus support and subsequent stress release, this application achieves dual optimization of mine safety and resource recovery, exhibiting significant technical advantages. First, this application scientifically calculates the initial pillar size using a rheological surplus coefficient, intentionally creating a "size surplus" in the early stages of mining. This allows the surface layer to act as an energy dissipation zone, effectively buffering the severe stress adjustment of the surrounding rock in the early stages of deep mining and avoiding brittle failure. Second, this application innovatively introduces a joint criterion based on surface damage and fracture convergence, accurately locking the "safe time window" for pillar trimming. This ensures operations are carried out when surface energy absorption is complete and the core is undamaged, avoiding the risks of blind mining. Furthermore, this application employs non-explosive mechanical cutting techniques (such as milling), completely abandoning explosive blasting and eliminating the disturbance of the elastic core zone of the pillar under high stress by blasting shock waves. This significantly improves the safety of mining operations and ensures the long-term stability of the final pillar. Finally, this method recovers the surface stripped material of the pillar, which was originally considered waste, as an effective resource. Without increasing the additional backfilling cost, it significantly improves the recovery rate of the ore body and realizes efficient, safe and refined mining of deep mineral resources. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart of the protective recovery method of the present invention.

[0017] Figure 2 This is a diagram showing the geometric dimensions of the pillar and the definition of the sacrificial layer in this invention. Detailed Implementation

[0018] Example 1 like Figure 1 As shown, a room-and-pillar method for protective pillar mining in a medium-deep, gently dipping thin ore body is described. This method establishes a dynamic balance system between initial surplus support and subsequent stress release. The steps include: S1: Construct an initial pillar system with ground pressure buffering capacity. Calculate and deploy initial pillars with size surplus in the early stage of ore body mining. Use this size surplus to establish an elastic core zone to cope with the initial surrounding rock stress. S2: Establish a monitoring mechanism for the surface damage evolution of the pillar, and collect data on the physical morphological changes and internal stress of the pillar surface in real time during the mining process; S3: Execute stress release trigger judgment based on damage threshold, calculate the bearing state of the pillar according to monitoring data, and generate a repair command when it is determined that the surface of the pillar has completed energy absorption and no deep damage has occurred. S4: Implement non-blasting precision stripping and mining operations, respond to adjustment instructions, use mechanical cutting methods to remove the damaged parts of the pillar surface, adjust the initial pillar to the final design size, and recover ore resources while releasing the high stress on the surface.

[0019] The core concept of this method lies in breaking away from the static design thinking of constant pillar size in the traditional room-and-pillar method, and innovatively establishing a dynamic balance system between initial surplus support and subsequent stress release. Step S1 involves constructing an initial pillar system with ground pressure buffering capacity, intentionally designing a size surplus larger than the permanent support requirement in the early stages of mining. This surplus acts as a sacrificial layer, used to absorb deformation energy during the initial stage of intense surrounding rock stress adjustment, protecting the core bearing area from damage. Step S2 establishes a monitoring mechanism for the evolution of pillar surface damage, using non-contact methods to acquire surface physical morphology and internal stress data, providing quantitative basis for subsequent decision-making. Step S3 executes a stress release trigger judgment based on damage thresholds. Only when monitoring data indicates that the pillar surface has completed its energy absorption mission and the core area remains stable is a trimming command generated, thus avoiding the safety hazards caused by blind mining. Step S4 implements non-blasting precision stripping mining operations, using mechanical cutting methods to physically remove the damaged surface layer and adjust the pillar to the final design size. The beneficial effect of this claim is that, through the above-mentioned dynamic adjustment steps, it not only solves the problem of brittle fracture of small-sized pillars in deep high-stress environments, but also solves the problem of resource waste caused by large-sized pillars, thus achieving a dual improvement in mine safety and resource recovery rate.

[0020] In the preferred scheme, in step S1, to achieve the long-term stability of the pillar under rheological pressure conditions, a derivation logic based on Protodyakonov's pressure arch theory combined with rheological surplus correction is used to determine the initial pillar side length. First, the physical and mechanical parameters of the ore and rock are obtained through on-site drilling and sampling. Then, the theoretical minimum width required to prevent shear failure of the roof is calculated. Based on this, a rheological surplus coefficient is introduced to compensate for the strength decay caused by the time effect. The specific calculation formula is as follows: ; In the formula Represents the span of the mine, This represents the average unit weight of the overlying rock strata. Represents burial depth. Represents the ultimate bearing strength of the pillar. Represents the design recovery rate; the rheological surplus coefficient introduced in the formula The calculation model used to quantify the long-term weakening effect of geological structures on ore pillars is as follows: ; in For vertical ground stress, The uniaxial compressive strength of the ore and rock. As a correction factor for the influence of on-site geological structures, the above-mentioned rheological surplus coefficient is used. The formula calculation ensures that the initial pillar has sufficient elastic core expansion space in the early stage of mining disturbance.

[0021] formula The design basis for the initial pillars was clarified. Represents the span of the mine, This represents the average unit weight of the overlying rock strata. Represents burial depth. Represents the ultimate bearing strength of the pillar. Representing the design recovery rate, this section determines the theoretical minimum width for maintaining roof stability based on Protodyakonov's pressure arch theory. A rheological surplus coefficient is then introduced based on this. Its computational model The unique characteristics of deep environments were fully considered. Among them... For vertical ground stress, The uniaxial compressive strength of the ore and rock. This is a correction factor for the influence of on-site geological structures. The beneficial effect of this claim is that, through a quantitative formula, the influence of geological structures, stress levels, and burial depth on the rheological properties of rocks is transformed into specific dimensional increments, ensuring that the core elastic core of the initially designed pillar can still meet the requirements for permanent support after experiencing initial ground pressure activity.

[0022] In the preferred embodiment, the monitoring mechanism in step S2 employs a non-contact multi-dimensional monitoring network, including an array of high-definition industrial cameras and laser scanners arranged around the pillar, using image recognition technology to capture and calculate the spalling depth on the pillar surface in real time. and surface crack development density Simultaneously, the peak value of the core vertical stress is obtained by combining the vibrating wire stress gauge pre-embedded in the center of the mine pillar, and all the above data are transmitted to the ground central processing terminal in real time for time-series analysis.

[0023] Employing a non-contact, multi-dimensional monitoring network composed of high-definition industrial cameras and laser scanners, it can capture minute changes on the surface of the ore pillar with high precision and calculate the spalling depth in real time. and surface crack development density Simultaneously, the peak vertical stress of the core is obtained by combining a vibrating wire stress gauge pre-embedded in the center of the mine pillar, and the data is transmitted to the ground central processing terminal. The beneficial effect of this claim is that it constructs a comprehensive three-dimensional sensing network from surface morphology to internal stress, overcoming the problems of strong subjectivity, large lag, and high safety risks of traditional manual inspection, providing accurate, real-time, and objective data support for subsequent adjustment decisions, and ensuring the accuracy of subsequent process steps.

[0024] In the preferred scheme, in step S3, to accurately identify the optimal time for pillar trimming, a joint criterion function based on surface damage stripping degree and fracture convergence is constructed. A comparison algorithm is continuously run through the central processing terminal, and a trimming command is triggered only when the monitoring data simultaneously satisfy the following inequality conditions: ; In the formula, This represents the depth of spalling on the surface of the pillar monitored in step S2. This represents the initial pillar side length determined in step S2. This represents the preset surface damage and peeling threshold, which is set to a value between 0.05 and 0.15. This represents the surface crack development density monitored in step S2. Represents the monitoring time. This represents the rate of change of fracture density over time. This step, through the above mathematical criteria, strictly locks in the only time window when the surface of the pillar is sufficiently damaged and the fracture development tends to be stable, avoiding the risk of premature repair during the stress active period leading to secondary expansion of newly formed fractures into the core area.

[0025] inequality Used to determine whether the surface damage has reached the expected level, that is, whether the sacrificial layer has fully played its role in pressure relief and energy absorption. For the depth of peeling of the flakes, This is the initial pillar side length. This represents the surface damage and peeling threshold. Simultaneously, the inequality... Used to determine whether fracture development tends to converge and stabilize, among which The density of surface crack development, The beneficial effect of this claim is that by setting dual constraints, the only safe time window for pillar repair is precisely locked, which not only prevents premature intervention before the surface is sufficiently damaged, leading to insufficient resource recovery, but also prevents forced operation during the dangerous period of accelerated fracture expansion from inducing instability, thus ensuring the safety of construction from the algorithm level.

[0026] In the preferred embodiment, the non-explosive precision stripping and mining operation in step S4 adopts a symmetrical layered cutting process. This process divides the height of the pillar to be stripped into multiple horizontal cutting layers. For each horizontal cutting layer, the excavation equipment performs ring cutting along the circumferential tangential direction of the pillar and controls the depth of a single cut to not exceed 0.5 meters, so as to avoid sudden changes in the core stress of the pillar due to instantaneous large-volume unloading.

[0027] A symmetrical layered cutting process is employed to divide the pillar height into multiple horizontal layers, with the depth of each cut strictly controlled to not exceed 0.5 meters. The beneficial effect of this method is that this micro-cutting, layered, circumferential approach smoothly releases the elastic potential energy accumulated on the surface, avoiding the impact pressure effect caused by the instantaneous unloading of large volumes of rock, preventing secondary damage to the pillar core due to sudden stress changes, and ensuring the continuity and stability of the support system during the finishing process.

[0028] In the preferred embodiment, the excavating equipment used in the non-blasting precision stripping and mining operation is equipped with a laser ranging and guidance system. This system establishes a three-dimensional spatial coordinate system during the operation, monitors and provides feedback on the position information of the cutting head in real time, and automatically adjusts the trajectory of the robotic arm to control the deviation between the geometric center of the cut pillar and the initial geometric center of the pillar. The following conditions must be met: ; in To ensure the final design dimensions after stripping, high-precision geometric center control is used to prevent eccentric structures in the pillars caused by human error, thereby avoiding asymmetric instability of the roof induced by additional eccentric torque.

[0029] like Figure 2 As shown, the inequality Geometric center deviation after cutting Strict restrictions were imposed, among which The final design dimensions after stripping are specified. The beneficial effect of this claim is that, through high-precision automated guidance control, the problem of pillar eccentricity caused by human error is eliminated, preventing additional eccentric moments caused by the offset of the pillar's bearing center. This avoids asymmetric instability of the roof due to uneven stress, further improving long-term safety after mining.

[0030] In the preferred embodiment, the protective mining method further includes a step of quantitatively assessing the incremental resource recovery. This involves collecting, weighing, and converting the ore fragments removed by physical cutting in step S4, whereby the volume of the recovered pillar surface ore is calculated. Calculate using the following volume integral formula: ; In the formula, This represents the volume of the surface ore from the recovered pillar. This represents the total number of pillars that have undergone secondary stripping within the mining area. The index representing the number of the ore pillar. Represents the height of the pillar. Representing the The initial design side length of each pillar, Representing the The final design side length of each pillar after stripping; this step incorporates the dynamically adjusted resource increment into the mine's economic benefit evaluation system, achieving effective recovery of protective layer resources discarded by traditional processes.

[0031] formula The calculation logic for the volume of recovered ore has been clarified, among which... Represents the volume of waste recovered. This represents the total number of pillars. The height of the pillar. and These are the initial and final side lengths, respectively. The beneficial effect of this claim is that it allows for a direct and quantitative assessment of the direct economic benefits of the technical solution, demonstrating the significant advantages of this method in improving resource utilization, and fully reflecting the practicality and inventiveness of this application.

[0032] In the preferred embodiment, after step S4 is completed, a secondary verification step of the pillar stability is also included. Specifically, after the physical stripping is completed, the repaired pillar is continuously monitored for 24-32 hours using microseismic monitoring equipment to capture acoustic emission signals generated by micro-fractures inside the rock mass in real time. If the energy level of the monitored microseismic event is lower than the preset safety background value, the mining operation is determined to be completed; otherwise, the pillar core is determined to be damaged, and an emergency plan must be immediately activated to reinforce the pillar with local anchor bolts.

[0033] After the operation is completed, continuous monitoring for 24 to 32 hours is conducted using microseismic monitoring equipment, and the condition of the pillar is determined based on the energy level of the microseismic events. The beneficial effect of this claim is that it provides a final safety barrier for mechanical dressing operations, ensuring that the delivered pillars are indeed in a stable state, enabling timely detection and reinforcement measures for pillars with potential damage, eliminating post-mining safety hazards, and improving the closed-loop management of the entire process.

[0034] In the preferred embodiment, this protective mining method is suitable for medium-deep mining geological environments where the roof rock mass quality score RMR value is between 50 and 70 and the ore body dip angle is between 5 and 20 degrees. This method also establishes a geological adaptability feedback adjustment mechanism. When the RMR value of the roof rock mass quality score is monitored to be lower than 50 during the mining process, the system automatically feeds back and adjusts the rheological surplus coefficient in step S1. The area is increased by 20% to compensate for the stability risk caused by the decline in the quality of the roof rock mass by increasing the initial support area.

[0035] The RMR value of the roof rock mass is limited to between 50 and 70, and the dip angle of the ore body is between 5 and 20 degrees. It is stipulated that when the RMR value is below 50, the rheological surplus coefficient $\alpha$ is automatically increased by 20%. The beneficial effect of this claim is that it enhances the adaptability of the technical solution to changes in geological conditions, compensates for the risks brought about by the deterioration of geological conditions by automatically increasing the initial support area, ensures the universality and reliability of the method under different geological grades, and makes the scope of protection clearer and more explicit.

[0036] In the preferred embodiment, the mechanical cutting method used in step S4 is a hydraulic excavator with a rotary milling head. The hydraulic excavator uses high-speed rotating cutting teeth to grind and crush the ore and rock, and has the ability to perform three-dimensional free-degree cutting operations in a confined space. Moreover, the entire cutting process completely eliminates explosive blasting, thereby completely eliminating the cumulative damage caused by blasting shock waves to the elastic core area of ​​the ore pillar that has already been subjected to high stress.

[0037] The mechanical cutting method is a hydraulic excavator with a rotating milling head, emphasizing the elimination of explosive blasting. The beneficial effect of this claim is that it clarifies the hardware foundation for achieving non-explosive cutting, utilizes the grinding and crushing characteristics of the milling head to replace the impact crushing of traditional blasting, completely eliminates the cumulative damage of blasting shock waves to the elastic core region of the pillar under high stress, fundamentally solves the technical problem of pillar instability induced by blasting vibration in traditional processes, and represents a significant improvement over existing technologies.

[0038] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-2 As shown, this embodiment selects an underground copper mine as the application scenario. The ore body has a depth of 650 meters, which is a typical medium-deep mining environment. The average dip angle of the ore body is 12 degrees, the average thickness is 3.5 meters, the RMR value of the roof rock mass is 62, and the uniaxial compressive strength of the ore and rock is... The pressure is 90 MPa. In the initial stage of mining, technicians first performed step S1, using Protodyakonov's pressure arch theory combined with parameters such as the stope span to calculate the theoretical minimum pillar side length for maintaining roof stability without considering time effects, which is 3.8 meters. Subsequently, based on the rheological surplus correction formula proposed in this invention, and combined with on-site geological surveys, a structural influence correction factor was selected. The value is 0.28. Substituting the vertical ground stress (approximately 17.5 MPa) and burial depth data, the rheological surplus coefficient is calculated. Approximately 0.26. Based on this, the initial design side length of the pillar is determined. Set at 4.8 meters (i.e.) This size surplus constructed a "ground pressure buffer sacrificial layer" approximately 1 meter wide, such as... Figure 2 As shown, the aim is to utilize surface micro-fractures to absorb the deformation energy of the surrounding rock during the period of severe ground pressure adjustment in the early stages of mining, thereby protecting the core elastic zone from damage.

[0039] During the mining process, the monitoring mechanism of step S2 was strictly implemented. High-definition industrial cameras and laser scanners were deployed in an array around the pillar to construct a non-contact, multi-dimensional monitoring network. Simultaneously, a vibrating wire stress gauge was pre-embedded at the geometric center of the pillar. The monitoring system collected real-time data on the spalling depth of the pillar surface. Surface crack development density The data, including the peak vertical stress, is transmitted in real-time to a central processing terminal on the ground via industrial Ethernet. After approximately 60 days of ground pressure manifestation, monitoring data shows that the spalling depth of the surface layer of the pillar reaches 0.48 meters. At this point, the calculated surface damage and stripping degree... The value was 0.1, which exactly reached the preset threshold. (In this embodiment, the value is set to 0.1). Meanwhile, the system's time-series analysis of fracture evolution data shows the rate of change of fracture density over time. The value has changed from positive to negative, indicating that the fracture development has tended to converge and stabilize, and the core stress value is within the safe elastic range. Based on the above joint criteria, the central processing terminal determines that the surface layer of the pillar has completed its energy absorption mission and the core is intact, and then automatically generates a trimming command, proceeding to step S3.

[0040] Upon receiving the repair order, a hydraulic excavator equipped with a laser ranging and guidance system was dispatched to the mining area to carry out the non-explosive precision stripping operation in step S4. This excavator is equipped with a rotary milling head, utilizing mechanical grinding instead of traditional explosive blasting. A symmetrical layered cutting process was employed, dividing the 3.5-meter-high pillar into several horizontal cutting layers. For each layer, the robotic arm performed a spiral circular cut along the circumference of the pillar, strictly controlling the depth of each cut to 0.4 meters to smoothly release the high surface stress and prevent sudden unloading impact. During the cutting process, the laser guidance system provided real-time position information, automatically adjusting the robotic arm trajectory and controlling the deviation between the geometric center of the cut pillar and its initial center. At only 0.1 meters, far less than 5% (0.19 meters) of the final design size, the geometric symmetry of the support structure was ensured. Ultimately, the pillar size was reduced from the initial 4.8 meters. The length was precisely adjusted from 4.8 meters to 3.8 meters. 3.8 meters.

[0041] After the stripping operation was completed, a secondary stability verification step for the pillars was immediately initiated. Microseismic monitoring equipment was used to continuously monitor the repaired pillars for 26 hours. The results showed that the energy level of microseismic events remained consistently below the preset safety background value, indicating that the pillars were stable and required no additional reinforcement. Finally, the surface resources of the recovered pillars were quantitatively calculated using the resource assessment formula of this invention. The results showed that each pillar recovered an additional 30 cubic meters of high-grade ore. If 50 pillars are deployed throughout the mining area, the cumulative increase in ore recovery will be approximately 1500 cubic meters. This significantly improves the resource recovery rate without increasing backfilling costs, and effectively mitigates the safety risk of sudden pillar instability during deep mining through scientific stress management.

[0042] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A room-and-pillar method for protective pillar mining of gently dipping thin ore bodies at medium to deep depths, characterized by: This protective recovery method establishes a dynamic balance system between initial surplus support and subsequent stress release. The steps include: S1: Construct an initial pillar system with ground pressure buffering capacity. Calculate and deploy initial pillars with size surplus in the early stage of ore body mining. Use this size surplus to establish an elastic core zone to cope with the initial surrounding rock stress. S2: Establish a monitoring mechanism for the surface damage evolution of the pillar, and collect data on the physical morphological changes and internal stress of the pillar surface in real time during the mining process; S3: Execute stress release trigger judgment based on damage threshold, calculate the bearing state of the pillar according to monitoring data, and generate a repair command when it is determined that the surface of the pillar has completed energy absorption and no deep damage has occurred. S4: Implement non-blasting precision stripping and mining operations, respond to adjustment instructions, use mechanical cutting methods to remove the damaged parts of the pillar surface, adjust the initial pillar to the final design size, and recover ore resources while releasing the high stress on the surface.

2. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 1, characterized in that: In step S1, to achieve long-term stability of the pillar under rheological pressure conditions, a derivation logic based on Protodyakonov pressure arch theory combined with rheological surplus correction is used to determine the initial pillar side length. First, the physical and mechanical parameters of the ore and rock are obtained through on-site drilling and sampling. Then, the theoretical minimum width required to prevent shear failure of the roof is calculated. Based on this, a rheological surplus coefficient is introduced to compensate for the strength decay caused by the time effect. The specific calculation formula is as follows: ； In the formula Represents the span of the mine, This represents the average unit weight of the overlying rock strata. Represents burial depth. Represents the ultimate bearing strength of the pillar. Represents the design recovery rate; the rheological surplus coefficient introduced in the formula The calculation model used to quantify the long-term weakening effect of geological structures on ore pillars is as follows: ； in For vertical ground stress, The uniaxial compressive strength of the ore and rock. As a correction factor for the influence of on-site geological structures, the above-mentioned rheological surplus coefficient is used. The formula calculation ensures that the initial pillar has sufficient elastic core expansion space in the early stage of mining disturbance.

3. The method for protective pillar mining of gently dipping thin ore bodies in medium-deep regions according to claim 1, characterized in that: The monitoring mechanism in step S2 employs a non-contact, multi-dimensional monitoring network, which includes an array of high-definition industrial cameras and laser scanners arranged around the pillar. Image recognition technology is used to capture and calculate the spalling depth on the pillar surface in real time. and surface crack development density Simultaneously, the peak value of the core vertical stress is obtained by combining the vibrating wire stress gauge pre-embedded in the center of the mine pillar, and all the above data are transmitted to the ground central processing terminal in real time for time-series analysis.

4. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 3, characterized in that: In step S3, to accurately identify the optimal time for pillar trimming, a joint criterion function based on surface damage stripping degree and fracture convergence was constructed. A comparison algorithm was continuously run through the central processing terminal, and a trimming command was triggered only when the monitored data simultaneously met the following inequality conditions: ； In the formula, This represents the depth of spalling on the surface of the pillar monitored in step S2. This represents the initial pillar side length determined in step S2. This represents the preset surface damage and peeling threshold, which is set to a value between 0.05 and 0.

15. This represents the surface crack development density monitored in step S2. Represents the monitoring time. This represents the rate of change of fracture density over time. This step, through the above mathematical criteria, strictly locks in the only time window when the surface of the pillar is sufficiently damaged and the fracture development tends to be stable, avoiding the risk of premature repair during the stress active period leading to secondary expansion of newly formed fractures into the core area.

5. The method for protective pillar mining of gently dipping thin ore bodies in medium-deep regions according to claim 1, characterized in that: The non-blasting precision stripping and mining operation in step S4 adopts a symmetrical layered cutting process. This process divides the height of the pillar to be stripped into multiple horizontal cutting layers. For each horizontal cutting layer, the excavation equipment performs ring cutting along the circumferential tangential direction of the pillar and controls the depth of each cut to not exceed 0.5 meters, so as to avoid sudden changes in the core stress of the pillar due to instantaneous large-volume unloading.

6. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 5, characterized in that: The excavating equipment used in non-blasting precision stripping and mining operations is equipped with a laser ranging and guidance system. This system establishes a three-dimensional spatial coordinate system during the operation, monitors and provides feedback on the position information of the cutting head in real time, and automatically adjusts the trajectory of the robotic arm to control the deviation between the geometric center of the cut pillar and the initial geometric center of the pillar. The following conditions must be met: ； in To ensure the final design dimensions after stripping, high-precision geometric center control is used to prevent eccentric structures in the pillars caused by human error, thereby avoiding asymmetric instability of the roof induced by additional eccentric torque.

7. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 1, characterized in that: This protective mining method also includes a step for quantitatively assessing the incremental resource recovery. This involves collecting, weighing, and converting the ore fragments removed through physical cutting in step S4, specifically the volume of the recovered pillar surface ore. Calculate using the following volume integral formula: ； In the formula, This represents the volume of the surface ore from the recovered pillar. This represents the total number of pillars that have undergone secondary stripping within the mining area. The index representing the number of the ore pillar. Represents the height of the pillar. Representing the The initial design side length of each pillar, Representing the The final design side length of each pillar after stripping; this step incorporates the dynamically adjusted resource increment into the mine's economic benefit evaluation system, achieving effective recovery of protective layer resources discarded by traditional processes.

8. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 1, characterized in that: After step S4 is completed, a secondary verification step of the pillar stability is also included. Specifically, after the physical stripping is completed, the repaired pillar is continuously monitored for 24-32 hours using microseismic monitoring equipment to capture acoustic emission signals generated by micro-fractures inside the rock mass in real time. If the energy level of the monitored microseismic event is lower than the preset safety background value, the mining operation is determined to be completed. Otherwise, the pillar core is determined to be damaged, and an emergency plan must be immediately activated to reinforce the pillar with local anchor bolts.

9. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 1, characterized in that: This protective mining method is suitable for medium-deep mining geological environments where the roof rock mass quality score RMR value is between 50 and 70 and the ore body dip angle is between 5 and 20 degrees. This method also establishes a geological adaptability feedback adjustment mechanism. When the RMR value of the roof rock mass quality score is monitored to be lower than 50 during the mining process, the system automatically feeds back and adjusts the rheological surplus coefficient in step S1. The area is increased by 20% to compensate for the stability risk caused by the decline in the quality of the roof rock mass by increasing the initial support area.

10. The method for protective pillar mining of a medium-deep, gently dipping thin ore body using the room-and-pillar method according to claim 1, characterized in that: The mechanical cutting method used in step S4 is a hydraulic excavator with a rotary milling head. The hydraulic excavator uses high-speed rotating cutting teeth to grind and crush the ore and rock, and has the ability to perform three-dimensional free-degree cutting operations in a confined space. Moreover, the entire cutting process completely eliminates explosive blasting, thereby completely eliminating the cumulative damage caused by blasting shock waves to the elastic core area of ​​the ore pillar that has already been subjected to high stress.

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