Testing device and method for milltailing backfilling open pit induced boundary pillar damage

Abstract

The invention relates to the technical field of boundary pillar destruction induced by backfilling an open pit, in particular to a test device and method for boundary pillar destruction induced by backfilling an open pit with tailings. The conveying assembly is connected with the testing assembly and is used for uniformly inputting tailings into the testing assembly; the pressure control assembly is connected with the testing assembly and used for controlling the pressure in the testing assembly; and the monitoring part is arranged on the testing assembly and is used for monitoring data information in the testing assembly under the condition that the internal pressure of the testing assembly is changed. The conveying assembly provides uniformly distributed tailings for the testing assembly, the pressure control assembly simulates the actual pressure working condition, and the monitoring part obtains data in real time, so that a complete and effective experimental device is formed, and a simulation experiment on related conditions of milltailing backfilling open pit induced boundary ore pillar damage in a controllable and safe laboratory environment is realized; the problems of high experiment cost and high risk in traditional research are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of backfill in open pits inducing the failure of boundary pillars, and particularly relates to a test device and method for backfill in open pits with tailings inducing the failure of boundary pillars. Background Art

[0002] With the gradual reduction of shallow mineral resources, deep mining has become an inevitable trend. At the same time, the concepts of environmental protection and sustainable utilization of resources have become increasingly popular, and the technology of converting open-pit tailings backfill to underground mining has gradually emerged. On the one hand, it can effectively reduce the environmental pressure caused by tailings accumulation, reduce safety risks such as tailings dam failure, avoid occupying a large amount of land resources, and reduce the damage to the surrounding ecological environment. On the other hand, through reasonable tailings backfill, the stability of open-pit slopes can be improved, and the costs of slope monitoring and treatment can be reduced. However, so far, the technology of converting open-pit tailings backfill to underground mining is mostly in the experimental stage, and a large number of experiments are still needed to support the selection of key technical parameters. One of the more critical parameters is the thickness of the boundary pillar. As a key structure separating different mining areas or protecting important facilities, the stability of the boundary pillar is directly related to the overall safety of the mine. When the tailings are backfilled into the open pit, due to the interaction between the backfill body and the surrounding rock mass and the stress changes during the mining process, complex effects will be produced on the stability of the boundary pillar. If these influence mechanisms cannot be accurately grasped, it may lead to the instability and failure of the boundary pillar, and then trigger a series of safety accidents above and below the ground, posing a huge threat to the safe production of the mine; Existing such research often faces high experimental costs, mainly because traditional experimental methods require real simulation of the actual mine environment for large-scale experiments. From site preparation, material collection to equipment investment, a large amount of resources are consumed. At the same time, conducting experiments in actual scenarios is somewhat dangerous. For example, during the simulation of tailings backfill and mining stress changes, sudden situations such as the instability of boundary pillars in actual mines may occur, posing a serious threat to the lives of experimental personnel and experimental equipment. There is an urgent need to provide a test device and method for backfill in open pits with tailings inducing the failure of boundary pillars. Summary of the Invention

[0003] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a test device and method for backfill in open pits with tailings inducing the failure of boundary pillars, which solves the technical problems of high experimental costs and certain dangers in the existing related research on backfill in open pits with tailings inducing the failure of boundary pillars.

[0004] To achieve the above object, the main technical solutions adopted by the present invention include: In the first aspect, an embodiment of the present invention provides a test device for backfill in open pits with tailings inducing the failure of boundary pillars.

[0005] An experimental device for inducing the failure of the boundary ore pillar by backfilling open pits with tailings proposed in an embodiment of the present invention includes: A test component; A conveying component, connected to the test component, and used for uniformly inputting tailings into the test component; A pressure control component, connected to the test component, and used for controlling the pressure inside the test component; A monitoring component, arranged on the test component, and used for monitoring the data information inside the test component when the internal pressure of the test component is changed.

[0006] Optionally, the test component includes: A test box; A test plate, arranged inside the test box, so that a funnel-shaped open pit model is formed inside the test box; A boundary ore pillar model, arranged inside the test box and located at the bottom of the open pit model; An exploited body component model, arranged inside the test box and in contact with the bottom of the boundary ore pillar model, and used for supporting the boundary ore pillar model.

[0007] Optionally, the exploited body component model includes: A plurality of first exploited bodies, arranged in parallel inside the test box and in contact with the bottom of the boundary ore pillar model; A second exploited body, arranged between adjacent first exploited bodies and in contact with the bottom of the boundary ore pillar model.

[0008] Optionally, the conveying component includes: A protective shell, arranged on the test box, and a plurality of blanking ports communicating with the open pit model are formed at the bottom; A driving shaft, coaxially and rotatably installed inside the protective shell; Blocking plates, fixedly arranged on the driving shaft in a staggered manner, and when the blocking plates are in contact with the blanking ports, the blocking plates block the blanking ports; A storage component, communicating with the protective shell, and used for conveying tailings into the protective shell; A vibration component, arranged on the outer wall of the test box, and used for evenly spreading the tailings inside the open pit model.

[0009] Optionally, the storage component includes: A storage box, used for storing tailings; A conveying pipe, communicating between the storage box and the protective shell; A screw conveyor, arranged inside the conveying pipe, and used for conveying tailings.

[0010] Optionally, the monitoring component includes: A fiber Bragg grating sensor, arranged inside the boundary ore pillar model; A pressure sensor, arranged at the bottom of the exploited body component model; A number of acoustic emission probes are equidistantly arranged on one side of the test box; A thermal infrared camera is equidistantly arranged on the other side of the test box.

[0011] Optionally, the pressure control component includes: A hydraulic cylinder; A pressure plate is arranged on the top of the test box and connected to the output end of the hydraulic cylinder for changing the pressure in the open-pit model.

[0012] In a second aspect, an embodiment of the present invention provides a test method for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings.

[0013] A test method for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings proposed by the embodiment of the present invention uses the test device for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings as in the first aspect: Manufacture a model of the mining body assembly, a model of the boundary ore pillar, and a model of the open-pit that are successively connected. The model of the mining body assembly includes a first mining body and a second mining body arranged adjacent to each other; Uniformly lay tailings in the open-pit model and compact them, and the compactness ≥ 90% to form a filling model; Apply a vertical load to the filling model to obtain a compacted backfill model; After removing the first mining body and filling it with a filling body, then remove the second mining body. If the boundary ore pillar model is not damaged after mining, apply a static load to the backfill model at a rate of 0.1 MPa / min until the boundary ore pillar model is damaged. At the same time, obtain the historical data of the boundary ore pillar model and perform preprocessing to obtain processed data; Input the processed data into the hybrid deep learning model to obtain a trained hybrid deep learning model; Input the real-time data into the trained hybrid deep learning model to obtain the safety factor of the ore pillar; When 0.8 ≤ safety factor of the ore pillar < 1.0, reduce the loading rate to 0.05 MPa / min; When 0.5 ≤ safety factor of the ore pillar < 0.8, suspend applying the static load to the backfill model; When the safety factor of the ore pillar < 0.5, stop applying the static load to the backfill model and give an alarm, and save the experimental data.

[0014] Optionally, the steps of manufacturing the open-pit model and the boundary ore pillar model further include: Mix barite powder, river sand, gypsum and water in a ratio of 1:4:1.25:1.25, and pour out an open-pit model of 1:100 or 1:200, and cure for 7 days to form. Mix barite powder, river sand, gypsum and water according to the ratio of 1:3.75:1.5:1.25 to prepare a boundary ore pillar model, and bury it in the open-pit model at the designated position after curing for 7 days.

[0015] Optionally, the steps of making the filling model further include: Mix tailings, cement and water by mass ratio, where the cement content is 5%, 10%, 15%, the water-solid ratio is 0.2, and the particle size of the tailings is less than 2 mm.

[0016] The beneficial effects of the present invention are as follows: The test device and method for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings of the present invention include a test component, a conveying component and a pressure control component. The conveying component provides uniformly distributed tailings for the test component, the pressure control component simulates the actual pressure condition, and the monitoring component obtains data in real time, jointly constituting a complete and effective experimental device, realizing the simulation experiment of the relevant situation of the failure of the boundary ore pillar induced by backfilling the open-pit with tailings in a controllable and safe laboratory environment, and solving the problems of high experimental cost and high danger in traditional research. Description of the Drawings

[0017] Figure 1 It is a three-dimensional structural schematic diagram of the test device for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings of the present invention; Figure 2 It is a sectional structural schematic diagram of the test component of the present invention; Figure 3 It is a top view structural schematic diagram of the test component of the present invention; Figure 4 It is a sectional structural schematic diagram of the conveying component of the present invention; Figure 5 It is a sectional structural schematic diagram of the storage component of the present invention; Figure 6 It is a flow schematic diagram of the test method for inducing the failure of the boundary ore pillar by backfilling the open-pit with tailings of the present invention.

[0018] Description of the Reference Numerals 100 - Test component, 200 - Conveying component, 300 - Pressure control component, 400 - Monitoring component; 110 - Test box, 120 - Test plate, 130 - Boundary ore pillar model, 140 - Mining body component model; 210 - Protection shell, 220 - Drive shaft, 230 - Sealing plate, 240 - Storage component, 250 - Vibration component; 310 - Hydraulic cylinder, 320 - Pressing plate; 410 - Fiber Bragg grating sensor, 420 - Pressure sensor, 430 - Acoustic emission probe, 440 - Thermal infrared camera; 141 - First mining body, 142 - Second mining body; 241 - Storage bin, 242 - Conveyor pipe, 243 - Auger; 101 - Open - pit model, 201 - Feed opening. Detailed implementation mode

[0019] For better explaining the present invention for easy understanding, the present invention will be described in detail below with reference to the drawings through specific implementation modes. Among them, the orientation nouns such as "upper", "lower", etc. mentioned in this article are Figure 1 used as a reference for orientation.

[0020] To better understand the above - mentioned technical solution, the exemplary embodiments of the present invention will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to be able to convey the scope of the present invention completely to those skilled in the art.

[0021] As Figures 1 to 5 shown, according to the first aspect of the embodiments of the present application, a test device for induced boundary pillar failure in an open - pit backfilled with tailings is proposed, including: a test component 100; a conveying component 200, connected to the test component 100, for uniformly inputting tailings into the test component 100; a pressure control component 300, connected to the test component 100, for controlling the pressure inside the test component 100; a monitoring component 400, arranged on the test component 100, for monitoring the data information inside the test component 100 when changing the internal pressure of the test component 100.

[0022] The test device for induced boundary pillar failure in an open - pit backfilled with tailings provided by the embodiments of the present application includes a test component 100, a conveying component 200, and a pressure control component 300. Among them, the test component 100 provides a basic space for simulating the tailings backfilling of the open - pit and the stress situation of the boundary pillar in this environment, and is the core component where various experimental factors act and data are generated; The conveying component 200 is connected to the test component 100, and its main function is to uniformly input tailings into the test component 100. This component ensures that the tailings can enter the test component 100 in a stable and uniform manner, simulating the distribution state of the tailings during the actual backfilling process, providing a basis for accurately simulating the interaction between the tailings and the rock mass (boundary pillar) later. By controlling parameters such as the flow rate and flow volume of the conveying component 200, the accumulation situation of the tailings under different backfilling conditions can be accurately simulated.

[0023] The pressure control component 300 is connected to the test component 100 and is responsible for controlling the pressure inside the test component 100. During the actual mine exploitation process, pressure change is one of the key factors affecting the stability of the boundary pillar. The pressure control component can, through precise control means, simulate the pressure change conditions at different exploitation stages and under different working conditions, making the pressure environment inside the test component 100 as close to the actual situation as possible. The simulation can deeply study the influence of different pressure conditions on the stability of the boundary pillar, which is of great significance for determining a reasonable exploitation plan and boundary pillar parameters.

[0024] The monitoring component 400 is arranged on the test component 100. When the internal pressure of the test component 100 is changed, it can monitor the data information inside the test component 100 in real time, and can comprehensively reflect the data response of the boundary pillar during the tailings backfill and pressure change process. By collecting and analyzing these data, the monitoring component 400 can obtain the stability change situation of the boundary pillar under different experimental conditions. In the experimental method, the real-time data of the boundary pillar model 130 is collected in real time. These data are input into the hybrid deep learning model after preprocessing to obtain the safety factor of the pillar, and different experimental operations are taken according to this coefficient. The precise monitoring of the monitoring component 400 provides data support for the whole experiment, enabling researchers to comprehensively understand the mechanical behavior of the boundary pillar during the experiment, deeply analyze the internal law of the boundary pillar failure induced by the tailings backfill of the open pit, and provide indispensable data guarantee for evaluating the stability of the boundary pillar.

[0025] In summary, each component cooperates closely. The conveying component 200 provides uniformly distributed tailings for the test component 100, the pressure control component 300 simulates the actual pressure working conditions, and the monitoring component 400 obtains data in real time, jointly constituting a complete and effective experimental device, realizing the simulation experiment on the situation related to the boundary pillar failure induced by the tailings backfill of the open pit in a controllable and safe laboratory environment, and solving the problems of high experimental cost and high danger in traditional research.

[0026] As Figures 1 to 5 shown, in some examples, the test component 100 includes: a test box 110; a test plate 120, arranged inside the test box 110, so that a funnel-shaped open pit model 101 is formed inside the test box 110; a boundary pillar model 130, arranged inside the test box 110 and located at the bottom of the open pit model 101; and a mining body component model 140, arranged inside the test box 110 and in contact with the bottom of the boundary pillar model 130, for supporting the boundary pillar model 130.

[0027] In this technical solution, the test chamber 110 is the external frame structure of the test component 100, which plays a role in accommodating and supporting each internal component, provides a stable physical environment for the entire experiment, and ensures that each component can operate in a relatively enclosed and stable space during the experiment, avoiding interference from external factors; The test board 120 is arranged inside the test chamber 110, forming a funnel-shaped open-pit model 101 inside the test chamber 110. This funnel-shaped open-pit model 101 is part of the simulation of the actual open-pit mine morphology. In actual open-pit mining activities, the shape and structure of the open-pit have an important impact on the tailings backfilling and subsequent stress distribution. By constructing such a funnel-shaped open-pit model 101 inside the test chamber 110, the experiment can more realistically simulate the natural accumulation situation and pressure distribution characteristics of tailings in the open-pit. Different shapes and sizes of open-pits will result in different accumulation forms and stress transfer paths of tailings, and the funnel-shaped open-pit model 101 is more in line with the common morphology of actual open-pit mines, which can provide conditions closer to the actual working conditions for subsequent experiments and help improve the authenticity and reliability of experimental results.

[0028] The boundary pillar model 130 is arranged inside the test chamber 110 and at the bottom of the open-pit model 101. In actual mine mining, the boundary pillar model 130 is a key structure, and its stability is directly related to the overall safety of the mine. In this experiment, the boundary pillar model 130 is in a core position. Factors such as the filling of tailings and pressure changes in the open-pit model 101 will affect the boundary pillar model 130, thereby causing changes in its mechanical state. By directly monitoring and studying the boundary pillar model 130, it is possible to deeply understand the various forces acting on the boundary pillar and the changes in its stability during the process of tailings backfilling the open-pit, providing an important basis for the evaluation and protection of the stability of boundary pillars in actual mine mining.

[0029] The mining body component model 140 is arranged inside the test chamber 110 and is in contact with the bottom of the boundary pillar model 130, mainly used to support the boundary pillar model 130. In the actual mine environment, there is a mechanical interaction between the mining body and the boundary pillar. The mining body component model 140 simulates the structure and mechanical environment of the mining body in the actual mine. During the experiment, the mining body component model 140 needs to be operated according to the experimental steps to simulate the actual mine mining process.

[0030] Exemplarily, the spaces on both sides of the open-pit model 101 inside the test chamber 110 are filled, simulating the on-site rock state.

[0031] In summary, all components in the test assembly 100 cooperate closely. The test chamber 110 provides space guarantee, the test board 120 constructs the open-pit model 101, the boundary pillar model 130 serves as the core research object, and the mining body assembly model 140 simulates the mining environment. Such a design enables the test assembly 100 to accurately and effectively simulate the complex process of tailings backfilling the open-pit and the impact of mining activities on the stability of the boundary pillar in an actual mine, providing a solid foundation for the entire test device to achieve its functions.

[0032] As Figures 1 to 5 shown, in some examples, the mining body assembly model 140 includes: a plurality of first mining bodies 141, arranged in parallel in the test chamber 110 and in contact with the bottom of the boundary pillar model 130; and a second mining body 142, arranged between adjacent first mining bodies 141 and in contact with the bottom of the boundary pillar model 130.

[0033] In this technical solution, the number of the first mining bodies 141 is several, arranged in parallel in the test chamber 110 and in contact with the boundary pillar model 130. This setting mode simulates multiple mining units at different positions in actual mine mining. During the actual mining process, these scattered and parallelly arranged mining bodies gradually excavate the underground ore body, and each mining body may have different degrees of influence on the surrounding rock mass, including the boundary pillar. In the experimental environment, multiple parallel first mining bodies 141 can relatively truly restore the stress situation of this multi-source mining, providing simulation conditions for studying the influence of mining activities at different degrees on the boundary pillar.

[0034] The second mining body 142 is placed between adjacent first mining bodies 141 and is also in contact with the bottom of the boundary pillar model 130. The second mining body 142 is arranged between adjacent first mining bodies 141. In an actual mine, the ore bodies in different regions may be mined in a specific order according to factors such as geological conditions and mining plans. The setting position of the second mining body 142 enables this complex mining working condition to be simulated in the experiment. Its contact with the boundary pillar model 130 also transmits the force generated by mining to the boundary pillar, and due to its special position between the first mining bodies 141, it will change the transmission path and distribution form of the surrounding stress, thereby affecting the mechanical state of the boundary pillar.

[0035] As Figures 1 to 5As shown, in some examples, the conveying assembly 200 includes: a protective housing 210, which is disposed on the test box 110 and has a plurality of material dropping openings 201 formed at the bottom and communicating with the open-pit model 101; a drive shaft 220, which is coaxially and rotatably installed inside the protective housing 210; a sealing plate 230, which is fixedly arranged on the drive shaft 220 in an alternating manner, and when the sealing plate 230 contacts the material dropping opening 201, the sealing plate 230 seals the material dropping opening 201; a material storage assembly 240, which communicates with the protective housing 210 and is used to convey tailings into the protective housing 210; and a vibration member 250, which is disposed on the outer wall of the test box 110 and is used to evenly spread the tailings in the open-pit model 101.

[0036] In this technical solution, the protective housing 210 is installed on the test box 110, providing a protective and supporting structure for the internal components of the entire conveying assembly 200. The plurality of material dropping openings 201 formed at the bottom and communicating with the open-pit model 101 are the channels for the tailings to enter the open-pit model 101 from the conveying assembly 200. The material dropping openings 201 are arranged at equal intervals, providing a basic condition for achieving uniform laying.

[0037] The drive shaft 220 is coaxially and rotatably installed inside the protective housing 210 and is the core component for power transmission during the entire conveying process. Driven by an external power source, the drive shaft 220 can perform circular rotation, and its rotation provides power for the subsequent components connected to the drive shaft 220, enabling them to cooperate to complete the conveying operation of the tailings; The sealing plates 230 are fixedly arranged on the drive shaft 220 in an alternating manner. In cooperation with the material dropping openings 201, when the sealing plates 230 contact the material dropping openings 201, they can completely seal the material dropping openings 201 and prevent the tailings from falling. As the drive shaft 220 rotates, the sealing plates 230 leave the material dropping openings 201, and the tailings can then fall into the open-pit model 101 through the material dropping openings 201. The alternating arrangement enables the tailings to enter the open-pit model 101 from the protective housing 210 in an intermittent and controllable manner, which helps to precisely control the flow rate and falling position of the tailings, thereby improving the uniformity of the distribution of the tailings in the open-pit model 101.

[0038] The material storage assembly 240 communicates with the protective housing 210 and undertakes the task of conveying tailings into the protective housing 210, continuously and stably conveying the tailings into the protective housing 210. The presence of the material storage assembly 240 ensures an adequate supply of tailings during the conveying process and provides material support for continuously simulating the actual tailings backfilling process.

[0039] The vibration component 250 is arranged on the outer wall of the test box 110. Exemplarily, at least two vibration components 250 can be selected. The at least two vibration components 250 are equidistantly arranged on the outer wall surface of the test box 110. The main function is to make the tailings in the open-pit model 101 evenly spread. After the tailings enter the open-pit model 101 through the feeding port 201, relying solely on gravity cannot ensure that the tailings are completely evenly distributed. The vibration component 250 indirectly acts on the tailings in the open-pit model 101 by transmitting vibration energy to the test box 110. Under the vibration effect, the tailings particles are disturbed by an additional external force, can adjust their own positions, and gradually reach a more uniform distribution state, ensuring that the compaction degree of the tailings is relatively consistent throughout the open-pit model 101, thereby improving the authenticity and accuracy of the experimental simulation.

[0040] Through the coordinated cooperation of each component of the conveying assembly 200, that is, the storage component 240 provides tailings, the drive shaft 220 and the plugging plate 230 control the rhythm and position of the tailings falling, and the vibration component 250 assists the tailings to be evenly distributed, so as to realize the uniform tailings input into the open-pit model 101 in the test assembly 100, providing a good material laying foundation for studying the influence of tailings backfilling on the boundary pillar in subsequent experiments.

[0041] As Figures 1 to 5 shown, in some examples, the storage component 240 includes: a storage tank 241 for storing tailings; a conveying pipe 242 connected between the storage tank 241 and the protective shell 210; and an auger 243 arranged in the conveying pipe 242 for conveying tailings.

[0042] In this technical solution, the storage tank 241 is a container for storing tailings. Its main function is to serve as a "warehouse" to hold a certain amount of tailings to meet the continuous conveying requirements during the experiment; the conveying pipe 242 is a "bridge" connecting the storage tank 241 and the protective shell 210, playing the role of communicating two important components and realizing the directional conveying of tailings. It provides a closed path for the tailings to be transported from the storage area to the unloading area by connecting the storage tank 241 and the protective shell 210, preventing the tailings from scattering or being interfered by external factors during the conveying process. Exemplarily, the inner wall material can be selected from materials with smoothness and wear resistance to reduce the friction between the tailings and the inner wall of the pipe, reduce wear, and extend the service life of the conveying pipe 242; a reliable connection method ensures that there will be no detachment or leakage during the conveying of tailings, guaranteeing the tightness and stability of the entire conveying system.

[0043] The auger 243 is disposed inside the conveying pipe 242, also known as a screw conveyor. Its working principle is that the spiral blades rotate around the central axis, and during the rotation, the tailings are pushed forward along the direction of the spiral blades, thereby realizing the conveyance of the tailings from the storage bin 241 to the protective shell 210. This conveyance method can relatively smoothly and efficiently convey the tailings from one end to the other end, and the conveyance speed and flow rate of the tailings can be controlled by adjusting the rotation speed of the auger 243.

[0044] As Figures 1 to 5 shown, in some examples, the monitoring component 400 includes: a fiber Bragg grating sensor 410 disposed inside the boundary ore pillar model 130; a pressure sensor 420 disposed at the bottom of the mining body component model 140; a plurality of acoustic emission probes 430 equidistantly arranged on one side of the test box 110; and a thermal infrared camera 440 equidistantly arranged on the other side of the test box 110.

[0045] In this technical solution, the fiber Bragg grating sensor 410 is installed inside the boundary ore pillar model 130. During the tailings backfilling process and under the influence of mining activities, the mechanical state inside the boundary ore pillar model 130 will undergo complex changes, such as changes in the distribution of stress and strain. The fiber Bragg grating sensor 410 can accurately sense these changes in internal physical quantities. Due to the sensitive characteristics of the fiber Bragg grating to environmental parameters, when stress or strain changes occur inside the boundary ore pillar model 130, it will cause corresponding changes in the reflection wavelength of the fiber Bragg grating. By detecting this wavelength change, the real-time information of the internal stress and strain of the boundary ore pillar model 130 can be obtained, which is of crucial significance for deeply understanding the internal stress conditions of the boundary ore pillar under different working conditions and judging whether it is approaching the failure state, and helps researchers accurately grasp the change process of the stability of the boundary ore pillar.

[0046] The pressure sensor 420 is placed at the bottom of the mining body component model 140. During the mining simulation process, the mining body component model 140 will exert a pressure on the lower part. The role of the pressure sensor 420 is to accurately measure the magnitude and change of this pressure. By obtaining the pressure data exerted by the mining body component model 140 on the bottom, the force condition of the mining activities on the lower strata can be understood, which is of important value for studying how the mining activities affect the boundary ore pillar through the bottom. At the same time, combined with other monitoring data, it can more comprehensively analyze the mechanical transmission path and influence range of the mining activities in the entire experimental system, providing important pressure parameter basis for deeply studying the relationship between tailings backfilling and the failure of the boundary ore pillar.

[0047] A number of acoustic emission sensors 430 are equidistantly arranged on one side of the test chamber 110. Acoustic emission is an elastic wave phenomenon generated during the stress deformation or fracture of materials. In the experiment, when the boundary ore pillar model 130 undergoes minor deformation, crack propagation, and ultimate failure, acoustic emission signals will be generated. The equidistantly arranged acoustic emission sensors 430 can receive these acoustic emission signals within a large range, convert them into electrical signals for transmission and analysis. By monitoring and analyzing the acoustic emission signals, researchers can obtain information on the internal deformation and damage development of the material, such as determining the initiation location, propagation direction, and propagation rate of cracks, etc.

[0048] Thermal infrared cameras 440 are equidistantly arranged on the other side of the test chamber 110. During the experiment, due to factors such as backfill of tailings, mining activities, and stress deformation of components, the surface temperatures of various objects in the test chamber 110 will change. The thermal infrared cameras 440 can receive the infrared rays radiated by the objects, convert them into thermal images, and intuitively present the distribution of the surface temperatures of the objects and their changes over time. By using the thermal infrared cameras 440 for monitoring, temperature anomaly regions during the experiment can be discovered. These regions may be related to phenomena such as stress concentration, energy dissipation, and damage development inside the objects. By analyzing the temperature changes, the distribution and conversion of energy during the experiment can be further understood, providing useful supplementary information for comprehensively studying the physical process of boundary ore pillar failure induced by tailings backfill in open-pit mines.

[0049] As Figures 1 to 5 shown, in some examples, the pressure control assembly 300 includes: a hydraulic cylinder 310; a pressure plate 320, which is arranged on the top of the test chamber 110 and is connected to the output end of the hydraulic cylinder 310 for changing the pressure inside the open-pit model 101.

[0050] In this technical solution, the hydraulic cylinder 310 is the power source of the pressure control assembly 300. It generates a powerful driving force through the pressure change of hydraulic oil. In the experimental device, by controlling the telescopic movement of the piston rod of the hydraulic cylinder 310, an adjustable power output is provided for the entire pressure control assembly 300, which is the core driving component for realizing pressure change.

[0051] The pressure plate 320 is arranged on the top of the test chamber 110 and is tightly connected to the output end of the hydraulic cylinder 310. It is like a "pressure transmission messenger" that evenly applies the force generated by the hydraulic cylinder 310 to the tailings in the open-pit model 101. The pressure plate 320 is located in the middle of the open-pit model 101. Exemplarily, the length can be selected to be half of the length of the top of the open-pit model 101 to ensure that when it contacts the top of the open-pit model 101, the received pressure can be more evenly distributed on the surface of the open-pit model 101. Among them, the maximum pressure load is 1 MPa.

[0052] Exemplarily, the pressure plate 320 can be of various different sizes and is selected and replaced for installation at the output end of the hydraulic cylinder 310.

[0053] When the pressure inside the open-pit model 101 needs to be changed during the experiment, the external hydraulic control system will adjust the hydraulic oil condition inside the hydraulic cylinder 310 according to the set parameters. For example, increasing the pressure of the hydraulic oil prompts the piston rod of the hydraulic cylinder 310 to extend. The extension of the piston rod drives the connected pressure plate 320 to move downward. The pressure plate 320 gradually approaches and generates pressure on the top of the open-pit model 101. This pressure is transmitted to various parts inside the open-pit model 101 through the tailings sand, thereby realizing the increase in the pressure inside the open-pit model 101. On the contrary, if the pressure needs to be reduced, the hydraulic control system will reduce the pressure of the hydraulic oil inside the hydraulic cylinder 310, the piston rod retracts, and the pressure plate 320 moves upward, reducing the pressure on the open-pit model 101. In this way, the pressure control assembly 300 can accurately and continuously change the pressure inside the open-pit model 101 to meet the requirements of pressure simulation under different experimental conditions, making the experimental results closer to the actual situation and being conducive to in-depth research on the relationship between tailings backfill, open-pit pressure, and the stability of the boundary ore pillar.

[0054] As Figure 6 shown, according to the second aspect of the embodiments of the present application, a test method for inducing the failure of the boundary ore pillar by tailings backfill in an open-pit is proposed, using the test device for inducing the failure of the boundary ore pillar by tailings backfill in an open-pit proposed in the first aspect above: S100: Fabricate a mining body component model 140, a boundary ore pillar model 130, and an open-pit model 101 that are successively connected. The mining body component model 140 includes a first mining body 141 and a second mining body 142 that are adjacently arranged; In step S100, the steps of fabricating the open-pit model 101 and the boundary ore pillar model 130 further include: mixing barite powder, river sand, gypsum, and water in a ratio of 1:4:1.25:1.25, pouring out an open-pit model 101 with a scale of 1:100 or 1:200, and curing for 7 days to form; mixing barite powder, river sand, gypsum, and water in a ratio of 1:3.75:1.5:1.25 to prepare the boundary ore pillar model 130, and after curing for 7 days, burying it into the open-pit model 101 at the designated position.

[0055] S200: Uniformly lay tailings sand in the open-pit model 101 and compact it, and the compaction degree ≥ 90% to form a filling model; In step S200, the steps of fabricating the filling model further include: using a vibrating screen, passing through a 10-mesh square-hole screen to ensure that the particle size of the tailings sand is below 2 mm. The cementitious material is prepared by mixing tailings sand, cement, and water by mass ratio, where the cement content is 5%, 10%, 15%, and the water-solid ratio is 0.2; Exemplarily, ordinary Portland cement PO42.5 can be selected as the cement.

[0056] Filling parameter setting: The filling height is converted according to the scaled model (1:100) or (1:200), and the equivalent height is set to 100 m, with the model heights being 0.2 m, 0.4 m, and 1.0 m. Cementing conditions: Dry tailings, 0% cement, and cemented tailings with cement dosages of 5%, 10%, and 15%. Dry tailings filling: Start the conveying component 200 with a flow rate of 30 kg / min, and evenly lay the tailings at the bottom of the open-pit model 101, with each layer having a thickness of 10 cm and an error of ±1 cm. After each layer of filling, start the pressure plate 320 with a frequency of 50 Hz, an amplitude of 2 mm, apply a pressure of 0.5 MPa, and repeat the compaction 3 times to ensure that the compaction degree is ≥90%. Compaction degree calculation formula: ; where C is the compaction degree (%), ρ d is the measured dry density (g / cm³), and ρ max is the maximum dry density (g / cm³).

[0057] S300: Apply a vertical load to the filled model to obtain a compacted backfill model. Static load application: For the vertical load, the hydraulic cylinder 310 applies the static load at a rate of 0.1 MPa / min until the pressure corresponding to the equivalent filling height is reached.

[0058] S400: After removing the first mining body 141 and filling it with the filling body, then remove the second mining body 142. If the boundary pillar model 130 is not damaged after mining, apply the static load to the backfill model at a rate of 0.1 MPa / min until the boundary pillar model 130 is damaged. At the same time, obtain the historical data of the boundary pillar model 130 and perform preprocessing to obtain the processed data. Step S400 is for simulating mining disturbance. During the test process, record the strain response and acoustic emission signals of the boundary pillar model 130. First, simulate the extraction of one-step stope. Remove the first mining body 141 one by one. After complete removal, fill all the void positions with the simulated filling body one by one. Then, simulate the extraction of two-step stope. Remove the simulated second mining body 142 one by one. After completion, if the boundary pillar model 130 has not been damaged, apply the static load at a rate of 0.1 MPa / min until the boundary pillar is damaged.

[0059] Real-time monitor the internal strain distribution of the boundary pillar model 130 through the fiber Bragg grating sensor 410 at a sampling frequency of 1 kHz. Capture the event count rate and energy cumulative value of the acoustic emission signals through the acoustic emission probe 430, and use the wavelet threshold denoising method to eliminate high-frequency noise. Collect the surface temperature distribution of the boundary ore pillar model 130 at a frequency of 5 Hz by the thermal infrared camera 440, generate a thermal image, and smooth the temperature data using moving average filtering; Sensor calibration, fiber Bragg grating sensor 410: Apply a known displacement using a strain calibration frame with an accuracy of 1 μm to calibrate the strain sensitivity coefficient.

[0060] Sensor calibration, fiber Bragg grating sensor 410: Apply a known displacement using a strain calibration frame with an accuracy of 1 μm to calibrate the strain sensitivity coefficient ; where K ε is the strain sensitivity coefficient (pm / με), Δλ is the wavelength change (pm), λ 0 is the initial central wavelength (nm), and Δε is the strain change (με); Acoustic emission probe 430: Use the pencil lead break method, Hsu-Nielsen source, calibrate the sensitivity, and ensure the frequency response range is 20 kHz - 1 MHz; Sensor embedding: Drill a hole with a diameter of 5 mm inside the boundary ore pillar model 130, implant the fiber Bragg grating sensor 410, and seal it with epoxy resin to ensure that the strain transfer efficiency is ≥95%; Temperature field monitoring: The thermal infrared camera 440 collects the surface temperature distribution of the boundary ore pillar model 130 at a frequency of 5 Hz, generates a thermal image, and the resolution is 640×480; Wavelet threshold denoising: Perform 5-layer wavelet decomposition on the acoustic emission signal, with the basis function: db4, and use soft threshold processing to eliminate high-frequency noise; Moving average filtering: Apply a moving average with a window length of 10 to the temperature data, and the formula is: ; where T filtered is the filtered temperature value (°C), T i is the original temperature data point, and N is the size of the moving window; Feature extraction: Strain feature: Calculate the mean value ; variance ; is the average value of the strain, is the variance of the strain, n is the total amount of strain data, is the i-th strain data.

[0061] Acoustic emission frequency domain analysis: Extract the main frequency energy ratio through FFT, and the formula ; where E main is the main frequency band energy, and E total is the total energy.

[0062] S500: Input the processed data into the hybrid deep learning model to obtain the trained hybrid deep learning model; Input strain, acoustic emission, and temperature data into the hybrid deep learning model, the LSTM-CNN fusion architecture, calculate the safety factor (SF) of the ore pillar in real time, and dynamically adjust the loading conditions according to the early warning mechanism; Model architecture design: LSTM branch, the input is the strain and acoustic emission sequences with a time window length of 60 seconds, a sampling interval of 0.1 second, a total of 600 data points, 3 layers of LSTM units, 128 hidden layer nodes, output time-dependent feature vectors. CNN branch, the input is a crack image and a temperature heat map of 224×224 pixels, use the pre-trained ResNet-50 to extract spatial features. Fusion layer: Concatenate the outputs of LSTM and CNN, and through a fully connected layer, nodes 256→128→1, map to the safety factor (SF); Model training: Loss function, Huber loss, the formula is ; Optimizer: Adam optimizer, learning rate 1e-4, batch size 32, training period 100; where y is the true safety factor, ŷ is the predicted safety factor, and δ is the threshold parameter, set to 1.0.

[0063] S600: Input the real-time data into the trained hybrid deep learning model to obtain the safety factor of the ore pillar; the real-time data includes strain, acoustic emission, and temperature data. When 0.8 ≤ safety factor of the ore pillar < 1.0, reduce the loading rate to 0.05 MPa / min; when 0.5 ≤ safety factor of the ore pillar < 0.8, suspend the static load on the backfill model; when the safety factor of the ore pillar < 0.5, stop applying the static load to the backfill model and alarm, and save the experimental data.

[0064] Safety factor (SF) calculation logic: ; The critical load is fitted from historical test data; Three-level early warning mechanism: First-level early warning, 0.8 ≤ SF < 1.0, reduce the loading rate to 0.05 MPa / min, and manually check for data anomalies; Second-level early warning, 0.5 ≤ SF < 0.8, suspend loading; Third-level early warning SF < 0.5, immediately cut off the pressure control component 300, give an audible and visual alarm and save the experimental data.

[0065] Analysis of failure modes and calculation of critical parameters, the specific steps are as follows; Determination of failure mode: Tensile failure: Cracks symmetrically expand along the center line of the boundary ore pillar model 130, and acoustic emission events are concentrated in the upper and middle parts, with the coordinate x > 0.5L, where L is the height of the ore pillar; Shear failure: Cracks are obliquely crossed at an angle of 45° - 60°, and the cumulative value of acoustic emission energy accounts for ≥ 60% in the bottom area; Critical parameter calculation: Safe filling height: By fitting the test data through Logistic regression, the formula is: ; Cementation strength threshold: Analyze the failure probability using Weibull distribution to determine the minimum cement content under a 95% confidence interval; where, H safe is the safe filling height (m), H max is the maximum filling height of the test (m), k is the material attenuation coefficient, f c is the compressive strength of the cemented body (MPa), f 0 is the reference strength (MPa).

[0066] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0067] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium; it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0069] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "embodiment", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0070] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A test device for the destruction of boundary pillars induced by backfilling an open pit with tailings, characterized in that: include: TestComponent(100); A conveying assembly (200) connected to the testing assembly (100) and used to uniformly input tailings into the testing assembly (100); A pressure control component (300) connected to the test component (100) and used to control the pressure in the test component (100); A monitoring component (400) is arranged on the test component (100) and is used to monitor data information in the test component (100) when the internal pressure of the test component (100) is changed.

2. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 1, characterized in that: The test assembly (100) comprises: Test box (110); A test plate (120) is arranged inside the test box (110) so that a funnel-shaped open pit model (101) is formed inside the test box (110); A boundary pillar model (130) is disposed in the test box (110) and is located at the bottom of the open pit model (101); The mining body component model (140) is arranged in the test box (110) and is in contact with the bottom of the boundary pillar model (130) and is used to support the boundary pillar model (130).

3. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 2, characterized in that: The mining volume component model (140) includes: A plurality of first mining bodies (141) are arranged in parallel in the test box (110) and are in contact with the bottom of the boundary pillar model (130); The second mining body (142) is disposed between adjacent first mining bodies (141) and is in contact with the bottom of the boundary pillar model (130).

4. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 2, characterized in that: The conveying assembly (200) comprises: A protective shell (210) is disposed on the test box (110) and has a plurality of drop openings (201) formed at the bottom thereof and connected to the open pit model (101); A drive shaft (220) is coaxially rotatably mounted in the protective shell (210); The blocking plates (230) are staggered and fixedly arranged on the driving shaft (220), and when the blocking plates (230) are in contact with the blanking opening (201), the blocking plates (230) block the blanking opening (201); A material storage assembly (240) is communicated with the protective shell (210) and is used to transport tailings into the protective shell (210); A vibration component (250) is arranged on the outer wall of the test box (110) and is used to evenly spread the tailings in the open pit model (101).

5. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 4, characterized in that: The material storage component (240) comprises: A storage box (241) for storing tailings; A conveying pipe (242) connected between the material storage box (241) and the protective shell (210); The auger (243) is arranged in the conveying pipe (242) and is used to convey tailings.

6. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 2, characterized in that: The monitoring component (400) comprises: A fiber grating sensor (410) is arranged inside the boundary pillar model (130); A pressure sensor (420) is arranged at the bottom of the mining body component model (140); A plurality of acoustic emission probes (430) are equidistantly arranged on one side of the test box (110); The thermal infrared camera (440) is arranged at an equidistant position on the other side of the test box (110).

7. The test device for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 2, characterized in that: The pressure control assembly (300) comprises: Hydraulic cylinder (310); A pressure plate (320) is disposed on the top of the test box (110) and is connected to the output end of the hydraulic cylinder (310) and is used to change the pressure in the open pit model (101).

8. A test method for the destruction of boundary pillars induced by backfilling an open pit with tailings, characterized in that: A test device for inducing boundary pillar destruction by backfilling an open pit with tailings as described in any one of claims 1 to 7: Producing a mining body component model (140), a boundary pillar model (130), and an open pit model (101) that are successively connected, wherein the mining body component model (140) includes a first mining body (141) and a second mining body (142) that are adjacently arranged; Evenly laying tailings in the open pit model (101) and compacting it, with a compaction degree of ≥ 90%, to form a filling model; Applying a vertical load to the filling model to obtain a compacted backfill model; After the first mining body (141) is removed and filled with a filling body, the second mining body (142) is removed, and if the boundary pillar model (130) is not destroyed after mining, a static load is applied to the backfill model at a rate of 0.1 MPa / min until the boundary pillar model (130) is destroyed, and historical data of the boundary pillar model (130) is obtained and pre-processed to obtain processed data; Inputting the processed data into a hybrid deep learning model to obtain a trained hybrid deep learning model; Input the real-time data into the trained hybrid deep learning model to obtain the pillar safety factor; When the pillar safety factor is 0.8≤<1.0, reduce the loading rate to 0.05MPa / min; When the safety factor of the pillar is 0.5≤0.8, the static load is suspended on the backfill model; When the safety factor of the pillar is less than 0.5, the static load applied to the backfill model is stopped, an alarm is sounded, and the experimental data is saved.

9. The test method for inducing boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 8, characterized in that: The steps of making the open pit model (101) and the boundary pillar model (130) further include: Mix barite powder, river sand, gypsum and water in a ratio of 1:4:1.25:1.25, cast an open pit model (101) of 1:100 or 1:200, and cure for 7 days to form; Barite powder, river sand, gypsum and water are mixed in a ratio of 1:3.75:1.5:1.25 to prepare a boundary pillar model (130), which is then buried in an open pit model (101) at a designated position after curing for 7 days.

10. The test method for induced boundary pillar destruction by backfilling an open pit with tailings as claimed in claim 8, characterized in that: The step of making the filling model also includes: Tailings, cement and water are mixed according to the mass ratio, wherein the cement content is 5%, 10% and 15%, the water-solid ratio is 0.2, and the tailings particle size is less than 2mm.

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