Physical simulation experiment method for slope deformation and instability induced by strip mine slope coal pressing recovery

Abstract

The invention discloses a physical simulation experiment method for slope deformation and instability induced by strip mine slope coal pressing recovery. The physical simulation experiment method comprises the steps that selection of an experiment research unit and a simulation experiment device are prepared; mining cave construction experiment parameters are designed; the similar materials are prepared and piled according to the preset model shape and size, compaction is conducted in the closed space of the test bed, the compactness and uniformity of the model are ensured, and the actual geological conditions are simulated; simulating an open excavation process on the three-dimensional model and the two-dimensional model by adopting a mining fixed-axis punching and reporting system, and gradually carrying out tunnel copper group construction simulation according to a designed excavation sequence and excavation parameters; a panoramic phase three-dimensional laser scanner, a high-resolution digital camera and a deep space micro imaging system are comprehensively adopted to realize the whole-process three-dimensional monitoring of the deformation and damage of the end slope stope slope. The slope deformation instability mechanism is comprehensively revealed, the slope stability prediction accuracy is improved, the pressed coal recovery scheme is optimized, and the mine production safety risk is reduced.

Description

Technical Field

[0001] This invention belongs to the field of open-pit mining technology, specifically relating to a physical simulation method for slope deformation and instability induced by coal recovery from coal embankment in open-pit mines. Background Technology

[0002] Due to the limitations of open-pit mining technology, the amount of coal trapped under the slopes of open-pit mines in my country is enormous. In recent years, with the continuous implementation of the national concept of "safe, efficient, and green" development of coal resources, the issue of coal trapped under open-pit mine slopes and the recovery of residual coal have gradually gained attention. Slope mining technology is an advanced and mature mining method that combines traditional open-pit mining techniques with underground mining techniques. It has been widely and successfully applied in major coal-producing countries abroad, providing a new approach for the mining of coal trapped under open-pit mine slopes in my country. The final result of this mining method is the formation of a series of tunnels perpendicular to the slope direction at the lower part of the slope. The mining effects of both underground and open-pit mining methods are superimposed and mutually influential, ultimately forming a dynamic, multi-faceted composite system within a certain depth range of the slope. Since there is no support throughout the mining process, the supporting coal pillars left between the tunnels are used to support the weight of the overlying rock and soil. Once the supporting coal pillars become unstable, it will induce a chain reaction of damage to the coal pillar group, leading to a large-scale landslide on the mining slope. Ultimately, this may damage the normal mining, transportation, and drainage system of the open-pit mine and cause huge economic losses and casualties.

[0003] Currently, similar material simulation experiments are a commonly used and effective method for studying the mechanical properties and mining processes during end-face coal recovery. However, existing similar material simulation experimental devices have many limitations. In three-dimensional simulation experiments, the test platform structure is complex, and the setup and disassembly process is extremely cumbersome, consuming a lot of time and manpower, which seriously affects experimental efficiency; while the test platform in two-dimensional simulation experiments has poor stability, and the model is prone to deformation or displacement during the experiment, resulting in a significant reduction in the accuracy of experimental data.

[0004] Traditional simulation devices for recovering similar materials from coal seams often employ simple frame structures. While three-dimensional simulation devices can provide some experimental space, they present numerous inconveniences in terms of model adjustment, replacement, and data acquisition, and their overall strength and stiffness are insufficient to meet the demands of large-scale model simulations. Two-dimensional simulation devices, on the other hand, suffer from poor lateral constraint stability, failing to effectively prevent lateral displacement of the model, thus compromising the reliability of experimental results.

[0005] Furthermore, in the process of coal seam recovery in open-pit mines, the study of the tunnel excavation and deformation evolution laws is crucial for safe mining and disaster prevention. Similar material simulation experiments are a common method for studying such problems, the core of which is to simulate the stress and deformation process of actual ore seams through physical models. In these experiments, the accuracy and controllability of tunnel excavation directly affect the reliability of the experimental results. However, existing experimental equipment suffers from problems such as tunnel deviation, insufficient stability, poor dimensional adaptability, cumbersome installation, and excessive excavation intensity during the sequential tunneling construction of simulated mining tunnels, making it difficult to meet the requirements of high-precision simulation experiments.

[0006] Tunnel boring machines need to possess high rigidity, linear guidance, adjustable dimensions, and rapid installation capabilities. In existing technologies, tunnel boring machines mostly use simple tools (such as handheld drill bits or general-purpose cutting equipment), lacking specialized design, resulting in large deviations in the tunneling path, low efficiency, easy damage to the tunnel, and difficulty in adapting to the size requirements of different experimental models.

[0007] The first type of existing tunneling device is the electric tunneling device, which typically consists of an electric motor, a transmission mechanism, and a tunneling head. The electric motor provides power, which drives the tunneling head to rotate or move linearly through the transmission mechanism, thereby achieving the tunneling function. This device has higher efficiency and a certain degree of stability compared to manual tools. However, existing electric tunneling devices have some design shortcomings. For example, the material and shape of the tunneling head may not be ideal, leading to wear or inability to adapt to the cutting requirements of different materials during sequential tunneling in simulated mining operations; the overall structure of the tunneling device may not be compact enough, making it difficult to operate in a limited experimental space; moreover, the control precision for tunneling depth and direction is not high enough to meet the requirements of precise experiments.

[0008] The second type of existing tunneling device is based on hydraulic or pneumatic principles. Power is provided by a hydraulic or pneumatic system to control the movement of the tunneling head. This type of device has significant tunneling force and is suitable for similar materials with high hardness. However, its system is complex, costly, and difficult to maintain. Furthermore, due to the limitations of the response speed and control precision of hydraulic or pneumatic systems, it may not be able to achieve rapid and precise tunneling operations during simulated sequential tunneling construction, making it unsuitable for experimental scenarios requiring high-precision control.

[0009] Existing research methods have limitations in revealing the deformation and failure processes of three-dimensional geological bodies on slopes. Current technologies largely focus on single two-dimensional or three-dimensional model experiments. Two-dimensional model experiments struggle to comprehensively demonstrate complex three-dimensional deformation and failure phenomena, failing to accurately simulate the complex deformation and instability processes of actual open-pit mine slopes. They cannot effectively simulate and analyze the impact of three-dimensional structural surfaces (such as joints and fissures) within the slope on slope stability, or the interactions between different layers. Three-dimensional model experiments are limited by factors such as experimental equipment, model fabrication difficulty, and observation methods, resulting in relatively few related studies. Furthermore, many studies use non-realistic soil and rock materials, leading to significant discrepancies between experimental results and actual slope conditions. Regarding monitoring methods, both two-dimensional and three-dimensional model experiments mostly employ traditional methods, such as total station single-point monitoring. These methods can only perform periodic measurements at a limited number of pre-set monitoring points, making it difficult to capture subtle deformations across the entire slope surface. Moreover, in the complex and harsh mining environment, measurement efficiency is low, failing to achieve comprehensive, continuous, and real-time monitoring. Meanwhile, existing technologies lack comprehensive monitoring methods for slope internal and surface deformation, making it impossible to simultaneously obtain detailed deformation data for both the slope's interior and surface. This hinders a comprehensive and in-depth study of the slope deformation and instability process. In existing technologies, two-dimensional and three-dimensional model experiments have not been effectively combined and mutually verified. While two-dimensional model experiments can clearly demonstrate the slope's deformation characteristics and stress distribution in a plane, they cannot accurately reflect the deformation and failure characteristics of three-dimensional geological bodies. Although three-dimensional model experiments can accurately reflect the three-dimensional geological structure of the slope, internal monitoring methods are limited, making it impossible to directly observe the fracturing, sliding, and other failure phenomena of the soil and rock mass within the slope. The lack of effective comparative analysis and mutual verification between the two methods makes it difficult to comprehensively and accurately reveal the slope deformation and instability mechanism. Summary of the Invention

[0010] This invention aims to address the shortcomings of existing simulation experiments on slope deformation and instability induced by coal recovery at open-pit mine slopes. Existing technologies suffer from limitations in two-dimensional models to accurately represent the complex deformation of three-dimensional geological bodies. Furthermore, the materials used in three-dimensional models are often unrealistic, internal monitoring is limited, monitoring technology is outdated, and two-dimensional and three-dimensional experiments are not effectively combined, making it difficult to comprehensively reveal the slope deformation and instability mechanisms. This patent employs simultaneous two-dimensional and three-dimensional model experiments. The two-dimensional model displays planar deformation characteristics, while the three-dimensional model realistically reflects the geological structure. Real-world similar materials and various advanced monitoring technologies, such as three-dimensional laser scanning and oblique photogrammetry, are used to acquire comprehensive deformation data. By comparing and analyzing the results of the two-dimensional and three-dimensional experiments, mutual supplementation and verification are achieved, enabling precise research on the deformation and instability mechanisms. This patent provides a more comprehensive and accurate simulation experimental method, offering strong support for open-pit mine slope stability research and optimization of coal recovery schemes.

[0011] This invention proposes a high-precision indoor positioning method based on multi-source data fusion and neighborhood multilateral measurement, which specifically includes the following steps: Step 1, preparing the selection of experimental research units and simulation experimental devices;

[0012] Step two, design of experimental parameters for tunnel construction; specifically including:

[0013] 2.1) Study the engineering geological conditions and mining conditions of the slope, and confirm the stratigraphic parameters for model laying based on borehole data, geological profiles and physical and mechanical properties of coal and rock strata;

[0014] 2.2) Indoor tests were conducted on the three-dimensional model materials and the two-dimensional model materials, including direct shear tests, triaxial compression tests, and uniaxial compressive strength tests, in order to determine the physical and mechanical property parameters of the model materials;

[0015] 2.3) Based on the requirements of the physical and mechanical properties of the model materials, accurately calculate the material ratio of the three-dimensional model materials; the ratio of quartz sand to binder.

[0016] 2.4) Before excavation, design the excavation sequence and parameters, confirm the overall slope angle of the excavated slope, and confirm the physical dimensions of each mining operation in the project based on the actual mining conditions in the mining area.

[0017] 2.5) Based on the monitoring requirements of the mining tunnel construction process, confirm the relevant monitoring parameters in advance to provide technical support for later monitoring of slope displacement and internal pressure changes;

[0018] Step 3: Prepare and stack similar materials according to the predetermined model shape and size, and compact them in the closed space of the test bench to ensure the density and uniformity of the model and simulate the actual geological conditions.

[0019] Step four involves simulating the open-pit excavation process using a fixed-axis punching and cutting system on both 3D and 2D models. Following the designed excavation sequence and parameters, the construction of the tunnel complex is simulated step by step. During the construction process, the excavation rate and dimensions are precisely controlled to ensure consistency with actual working conditions.

[0020] 4.1) Carry out tunnel construction and intermittent filling;

[0021] 4.2) Carry out coal seam roadway construction and backfilling;

[0022] 4.3) Construct a spoil heap and prepare for coal seam construction;

[0023] 4.4) Construction and backfilling of the intermediate coal seam roadways;

[0024] The entire construction process is continuously monitored by a combination of pressure sensors, 3D laser scanners, UAV close-range photogrammetry, and endoscopic camera monitoring equipment.

[0025] Step 5: A comprehensive three-dimensional monitoring of the entire process of deformation and damage of the end-face mining slope is achieved by using a panoramic phase 3D laser scanner, a high-resolution digital camera, and a deep space micro-imaging system.

[0026] This invention simulates the entire process of slope deformation and failure induced by roadway group construction, reveals the slope deformation and failure mode and instability mechanism, identifies the triggering conditions and key parts of slope deformation and instability, and proposes a zoning method and stage division method for slope rock and soil deformation and failure during mining. This provides a basic basis for the study of the dynamic process and stability control method of slope rock mass failure in end-side coal mining.

[0027] This invention simultaneously conducts two-dimensional and three-dimensional model experiments: this is one of the core innovations of this invention. By conducting two-dimensional and three-dimensional model experiments simultaneously, the advantages of both are fully utilized, complementing and verifying each other, thus solving the problem in existing technologies where a single model experiment cannot fully reveal the slope deformation and instability mechanism. Two-dimensional model experiments can clearly demonstrate the deformation characteristics and stress distribution of the slope in a plane, while three-dimensional model experiments can realistically reflect the three-dimensional geological structure and internal failure process of the slope.

[0028] The invention utilizes a comprehensive multi-dimensional monitoring approach: It integrates various monitoring methods, including internal stress sensors, endoscopic cameras, 3D laser scanning, and oblique photogrammetry, to comprehensively monitor the deformation and damage of the slope's interior and surface. This multi-dimensional monitoring method can more accurately capture the mechanical response and damage phenomena of the slope during coal recovery, providing rich data support for in-depth research on slope deformation and instability mechanisms.

[0029] This invention relates to similar materials and model fabrication processes: Precise selection and proportioning of similar materials are crucial for accurate simulation, ensuring that the physical and mechanical properties of the model materials are similar to those of the actual rock and soil in the mining area. This invention determined suitable model material proportions through indoor experiments and employed layered filling and compaction processes to fabricate the model, guaranteeing its quality and similarity.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) Comprehensively revealing the deformation and instability mechanism of slopes: By conducting simultaneous two-dimensional and three-dimensional model experiments, combined with various monitoring methods, the deformation and instability mechanism of slopes during coal recovery from open-pit mine sidewalls can be comprehensively and accurately revealed. Two-dimensional model experiments can clearly demonstrate the deformation characteristics and stress distribution of slopes in a plane, while three-dimensional model experiments can realistically reflect the three-dimensional geological structure and internal failure process of slopes. The two complement and verify each other, providing richer information for a deeper understanding of slope instability mechanisms.

[0032] (2) Improve the accuracy of slope stability prediction: Based on the experimental method of this invention, more comprehensive and accurate data on slope deformation and failure can be obtained, thereby establishing a more realistic slope stability prediction model. Through the analysis of experimental data, the stability state of the slope under different coal mining and recovery conditions can be predicted more accurately, providing a scientific basis for formulating reasonable slope stability control measures.

[0033] (3) Optimize coal recovery schemes: Through simulation experiments on different coal recovery processes (such as tunnel construction and backfilling operations), the influence of these processes on slope stability is studied, thereby providing guidance for optimizing coal recovery schemes. For example, reasonable parameters such as tunnel spacing, backfilling time, and backfilling materials are determined to improve the coal recovery rate while ensuring slope stability.

[0034] (4) Reducing safety risks in mine production: The research results of this invention help to identify potential dangerous areas and critical stages of slope deformation and instability in advance, providing early warning information for mine production safety management. By taking corresponding stability control measures, the probability of slope instability accidents can be effectively reduced, ensuring the safety of mine production personnel and the normal operation of equipment. Attached Figure Description

[0035] Figure 1 This is a flowchart of the overall process of the physical simulation experiment method for slope deformation and instability induced by coal recovery from coal pile-up on the side of an open-pit mine, according to the present invention.

[0036] Figure 2 This is a diagram of the overall structure of the tunneling device used in the physical simulation experiment method for slope deformation and instability induced by coal recovery from coal embankment in open-pit mines, as described in this invention.

[0037] Figure 3 This invention relates to a physical simulation experimental method for slope deformation and instability induced by coal recovery from coal piles on the side of an open-pit mine, which uses a galvanized impact shovel rod and control handle structure.

[0038] Figure 4 This is a schematic diagram of the flange linear bearing installed inside the hole of the directional sleeve frame of the tunneling rod in the physical simulation experiment method for slope deformation and instability induced by coal recovery from the side slope of an open mine, as used in the present invention.

[0039] Figure 5 This is a schematic diagram of the detachable punching shovel used in the physical simulation experiment method of slope deformation and instability induced by coal recovery from open-pit mine side slopes in this invention.

[0040] Figure 6 This is a schematic diagram illustrating the application effect of the detachable punching shovel head used in the physical simulation experiment method for slope deformation and instability induced by coal recovery from open-pit mine side slopes in this invention.

[0041] Figure 7 This is a schematic diagram of three-dimensional laser scanning point cloud data obtained after preprocessing the initial point cloud data collected in the physical simulation experiment method of coal recovery induced by coal pressing on the side of open mine in this invention.

[0042] Figure 8 In the physical simulation experiment method of the present invention for the slope deformation and instability induced by coal recovery on the side slope of an open mine, during the scanning stage of the tunneling process, the point cloud data acquired by each scan is rapidly preprocessed and analyzed, and a schematic diagram of three-dimensional laser scanning point cloud data is obtained after excavation.

[0043] Figure 9 This invention provides a physical simulation experiment method for slope deformation and instability induced by coal recovery from the side slope of an open-pit mine. It involves using a drone equipped with a high-definition camera to take multi-angle photos of the experimental model and collect multi-angle image data.

[0044] Figure 10 In the physical simulation experiment method for slope deformation and instability induced by coal recovery from the side slope of an open-pit mine, the present invention involves periodically conducting drone aerial photography to collect image data and three-dimensional spatial information, thereby obtaining post-construction state model image acquisition.

[0045] Figure 11 In the physical simulation experiment method of the present invention for the slope deformation and instability induced by coal recovery on the side of open mine, for the key construction stage, a three-dimensional model of the outer edge surface of the slope is constructed by using real-scene modeling software based on the captured tilted images.

[0046] Figure 12 This is a schematic diagram of the screen displayed synchronously by an industrial endoscope and video monitoring during real-time monitoring of the tunnel interior in a physical simulation experiment method for slope deformation and instability induced by coal recovery from coal embankment in an open-pit mine, as described in this invention. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] Figure 1 The diagram illustrates the overall flowchart of a high-precision indoor positioning method based on multi-source data fusion and neighborhood multilateral measurement as described in this invention.

[0049] like Figure 1 As shown, the physical simulation experimental method for slope deformation and instability induced by coal recovery from open-pit mine side slopes according to the present invention specifically includes the following steps:

[0050] Step 1: Select the experimental research unit and prepare the simulation experimental setup.

[0051] 1.1) Based on the engineering geological conditions and mining conditions of open-pit coal mining, the present invention selects a wound area as the research unit, confirms the geometric similarity ratio of the simulation experiment and the scope of the test area, and prepares and installs the simulation experiment device before the experiment, including the experimental table, the mining tunnel construction device and the monitoring equipment.

[0052] The physical simulation system for slope deformation and instability induced by coal recovery from coal mining side slopes in open-pit mines of the present invention specifically includes: test bench columns, test bench steel plates, test bench main beams, test bench legs, and test bench baffles; all of the above components are made of steel.

[0053] 1.2) Figure 2 This is a diagram of the overall structure of the tunneling device used in the physical simulation experiment of slope deformation and instability induced by coal recovery from open-pit mine side slopes, as described in this invention. The tunneling device of this invention mainly consists of a tunneling rod directional sleeve and a punching shovel. The tunneling rod directional sleeve includes a tunneling rod quantitative sleeve support 1 fixed on the test bench, and separately symmetrically erected tunneling rod directional sleeve supports 2, wherein multiple support slots 3 are spaced apart on supports 1 and 2. The punching shovel includes a galvanized shovel rod 5, a detachable punching shovel head 6, and an operating handle 7. The overall structure is as follows: Figure 2 As shown.

[0054] The tunneling rod directional sleeve is made of galvanized channel steel with openings. The galvanizing treatment not only enhances the rigidity of the support but also gives it excellent moisture and corrosion resistance, extending its service life. The tunneling rod directional sleeve consists of a support 1 fixed to the test bench and two separately symmetrically mounted supports 2. All holes on the upper part of the two supports are precisely aligned along the axial direction of the shovel rod. Figure 3 As shown, the impact shovel uses a galvanized shovel bar and an operating handle structure.

[0055] A flanged linear bearing is installed inside the hole of the directional sleeve of the tunneling rod. The bearing bore diameter matches the diameter of the impact shovel rod, ensuring that the shovel rod does not rotate but can only move freely back and forth along its axial direction without deviation or wobbling. The flanged linear bearing has high precision and high load-bearing capacity, capable of withstanding various forces and torques during the sequential tunneling construction process in simulated mining tunnels, ensuring the stable operation of the device. Figure 4 As shown.

[0056] One of the structural features of the directional sleeve used in the physical simulation experiment method for slope deformation and instability induced by coal recovery on the side of an open mine in this invention is that the flange linear bearing is combined with the galvanized rod of the rigid impact shovel to restrict lateral displacement, thereby achieving linear guidance.

[0057] Another feature of the structure of the directional sleeve used in the physical simulation experiment method for slope deformation and instability induced by coal recovery on the side of open mine in this invention is that the multi-hole design of the directional sleeve supports height adjustment (±50mm range), thereby realizing arbitrary adjustment position;

[0058] Another feature of the structure of the directional sleeve used in the physical simulation experiment method for slope deformation and instability induced by coal recovery on the side of an open mine in this invention is that the punching shovel head and the galvanized shovel rod of the impact shovel adopt a snap-fit ​​interface, which can be replaced within 10 seconds, thereby realizing modular connection.

[0059] The galvanized shovel bar features a custom-designed rigid linear shaft, offering high strength and rigidity to ensure it won't deform or bend during simulated tunneling, thus guaranteeing tunneling stability. Its surface is finely machined, smooth and burr-free, reducing friction with surrounding materials. A front-mounted operating handle ensures comfortable grip and force application during use. The handle is welded to the galvanized shovel bar, providing high strength to withstand significant impact and torque, ensuring it won't loosen or detach during frequent cutting operations.

[0060] like Figure 5 As shown, the detachable punching head 6 is made of thin steel with a square cross-section. The side length can be flexibly configured as needed. The head has a beveled opening, and the four sides of the shovel are sharpened.

[0061] The detachable punching head 6 is cut and welded from a special manganese steel material, ensuring maximum hardness and sharpness. This experiment designed two corresponding sizes of square tunneling heads for two different roadways, with side lengths of 45mm and 50mm respectively. This allows for experiments with different material ratios and roadway sizes, and the application results are as follows. Figure 6 As shown.

[0062] 1.3) This device allows for the construction of a series of mining tunnels perpendicular to the slope direction at any designated location on the front of the model. It offers advantages such as flexible construction location, controllable construction precision, and a more realistic simulation of the disturbance characteristics of the surrounding rock in the mining area throughout the construction process. The application results are as follows: Figure 6 As shown.

[0063] Regarding the shape of the punching head 6, a circular or other polygonal shape can be considered to adapt to different tunneling requirements. For the material of the galvanized rod of the impact shovel, in addition to a rigid linear optical shaft, other high-strength, high-rigidity alloy materials can also be selected. In the fabrication of the tunneling rod directional sleeve, in addition to galvanized channel steel, stainless steel or other materials with moisture-proof and corrosion-resistant properties can also be used. Furthermore, the entire tunneling device can be designed as a modular structure, facilitating combination and expansion according to different experimental requirements, such as adding a tunneling power unit or an automated control system, to achieve more complex and precise tunneling operations.

[0064] The core of the design of the entire fixed-axis punching tunneling system is to ensure the stability of the simulated mining tunnel during the sequential tunneling process. It ensures that a series of mining tunnels perpendicular to the slope direction can be constructed from any designated position on the front of the model into the interior of the slope. It has the advantages of flexible construction position, controllable construction accuracy, and the disturbance characteristics of the surrounding rock of the sidewall mining area during the entire construction process are closer to the actual site conditions.

[0065] Figure 3 In the physical simulation experiment method of the present invention for the slope deformation and instability induced by coal recovery on the side of open mine, the arbitrary adjustment position adopted is: the multi-hole design of the tunneling rod directional sleeve supports height adjustment (e.g., ±50mm range);

[0066] Installation sequence and steps of the experimental platform

[0067] Perform the installation in the predetermined sequence:

[0068] (a) First, install the test bench legs on the pre-leveled buried steel plate;

[0069] (b) Next, install the main beam, steel plate, columns and baffles of the test bench;

[0070] (c) Finally, the five main components, namely the tunneling frame, fixed beam, tunneling rod stabilizing beam, tunneling rod and tunneling head, are welded and fixed together, and the whole is painted with two coats of anti-rust paint. The topcoat is silver-gray, so as to meet the rust prevention of the test bench and achieve an aesthetic effect.

[0071] (d) After the five main components of the test bench (tunneling frame, fixed beam, tunneling rod stabilizing beam, tunneling rod, and tunneling head) are welded and fixed, the whole thing is painted with two coats of anti-rust paint, and the topcoat is silver-gray to meet the anti-rust effect of the test bench.

[0072] (e) Transportation and on-site assembly.

[0073] After the welding and processing of the five main components of the test bench were completed, they were transported to the laboratory and placed in the designated locations in preparation for the assembly of the test bench. At the laboratory site, M14 bolts with washers were used to connect the five components, and the threads were tightened to achieve a stable state, thus completing the overall installation of the experimental environment.

[0074] The 3D test bench boasts a large experimental space. Its pre-drilled holes on the main beam frame and flexible installation of the vertical connecting columns allow for rapid adjustment of the length and width of the experimental area to meet specific experimental needs. The height adjustability of the overlapping constraint side plates further enhances the bench's flexibility. This flexible and adjustable structural design not only improves the bench's versatility and adaptability but also ensures the stability and safety of the model during experiments.

[0075] The 3D experimental platform achieves flexible adjustment of the experimental area space through the pre-drilled holes on the main beam frame and the flexible installation design of the vertical connecting columns. During the experiment, different pre-drilled holes can be selected to install the vertical connecting columns according to the size requirements of the model, thereby adjusting the length and width of the experimental area. The layered installation design of the overlapping constraint side plates further enhances the adjustability of the experimental area height. This flexible and adjustable structural design provides great convenience for 3D similar material simulation experiments of different sizes and types, ensuring the efficiency and adaptability of the experimental process.

[0076] Test bench setup stage: Install column-type support legs and level the surface. Install the main beam frame onto the support legs to form the skeleton of the test bench. According to experimental requirements, select appropriate pre-drilled holes on the main beam frame, install vertical connecting columns, and adjust the length and width of the experimental area. Place the base steel plate on the main beam frame and secure it firmly. Next, install the overlapping constraint side plates, installing them sequentially from bottom to top according to the model height requirements to form a closed experimental space.

[0077] It is worth noting that the detachable templates around the three-dimensional test platform and on the left and right sides of the two-dimensional test platform in this invention facilitate operation and ensure the stability and safety of the model, which are key design and protection technologies.

[0078] It is worth noting that the three-dimensional test bench of this invention has a specific structure consisting of columns, main beams, legs, steel plates, and baffles, as well as a combination of detachable templates on the left and right sides and a closed structure at the front and rear of the two-dimensional test bench. The unique structural design ensures the strength, rigidity, and stability of the test bench, which is also the technical point to be protected.

[0079] In practical applications, the materials and some structural elements of the test bench can be appropriately adjusted according to specific experimental needs and conditions. For example, in terms of materials, in addition to the aforementioned steel profiles, other high-strength, high-rigidity engineering materials, such as aluminum alloy profiles, can be considered, although this may result in changes in cost and processing difficulty. In terms of structural design, the dimensions of the test bench can be appropriately scaled to accommodate experimental needs of different scales, while ensuring that its basic structure and functional characteristics remain unchanged to guarantee the accuracy and reliability of the experiments.

[0080] Step two, design of experimental parameters for the mining tunnel construction, specifically including:

[0081] 2.1) Study the engineering geological conditions and mining conditions of the slope, and confirm the stratum parameters for model laying based on borehole data, geological profiles and physical and mechanical properties of coal and rock strata.

[0082] Using a self-developed simulation experimental device, and based on the engineering geological and mining conditions of an open-pit coal mine in China, a cross-section was selected as the research unit. The stratigraphic parameters for model laying were confirmed based on borehole data, geological profiles, and physical and mechanical properties of the coal and rock strata. A scientific model similarity ratio was calculated and determined, and appropriate materials and proportions were selected to fabricate the experimental model. After the model materials reached the predetermined strength, open-pit excavation was carried out to form the end slope. Subsequently, simulations of roadway group construction, roadway filling construction, and transverse mining internal drainage construction, as well as single coal pillar failure experiments and segmented roadway filling experiments, were conducted according to the design parameters. Simultaneously, the stress distribution of the slope and the deformation and failure of the rock mass were monitored.

[0083] Based on the typical engineering geological model of the end-face mining slope established in the study, the slope rock mechanical property parameters and rock layer thickness required for the experiment are shown in Table 1.

[0084] Table 1 Physical and mechanical properties of slope soil and rock

[0085] Serial Number Rock strata name Thickness (m) Bulk density (kg / m3) Prototype compressive strength (MPa) 1 sandstone 8.2 2750 21.30 2 Sandy mudstone 18 2200 9.5 3 fine sandstone 16.4 2320 20.60 4 4-2 intermediate coal seam 5.6 1290 3.9 5 Sandy mudstone 25 2200 11.25 6 5-1 Upper Coal Seam 3 1190 4.8 7 siltstone 9.8 2280 20.60 8 Sandy mudstone 3.6 2100 10.15 9 5-1 coal seam 7.0 1190 4.8 10 Sandy mudstone 23 2200 11.35 11 Discarded materials —— 1850 ——

[0086] 2.2) Indoor tests were conducted on the three-dimensional model materials and the two-dimensional model materials, including direct shear test, triaxial compression test and uniaxial compressive strength test, in order to determine the physical and mechanical property parameters of the model materials.

[0087] The physical and mechanical parameters of materials, such as compressive strength, shear strength, elastic modulus, and Poisson's ratio, are determined to provide basic data for mechanical analysis during the experiment.

[0088] According to similarity theory, the experimental model and the physical prototype need to satisfy three similarity laws. According to the first law of similarity, to simulate the deformation and failure process of the end-face mining slope, there should be three aspects of similarity between the model and the prototype: geometric similarity, kinematic similarity, and dynamic similarity.

[0089] Based on the size of the experimental setup, and taking into account both the economy and feasibility of the construction, the model is required to have a similar geometry to the actual object.

[0090]

[0091] In the formula: a L — Length similarity constant; a A —Area similarity constant; a V —Volume similarity constant; L —Length; P —Prototype; M —Model.

[0092] In studying the failure of slope rock masses under long-term disturbance conditions, the temporal similarity between the model and the prototype should be considered. The relationship between the time similarity constant and the length similarity constant is as follows:

[0093]

[0094] In the formula: a t —Time similarity constant.

[0095] Strictly speaking, the strength curves of the model material and the original material should be similar, but this requirement is often difficult to meet. A simplified method is usually used, which is to take the envelope of the Mohr's circle as a straight line. To make the model's strength similar to the prototype, the following needs to be satisfied:

[0096] Or satisfy:

[0097] In the formula: — Compressive strength similarity constant; —Tensile strength similarity constant; a C — Cohesion similarity constant; —Internal friction angle similarity constant; P —Prototype; M —Model.

[0098] (4) Similar bulk density

[0099] The model and the physical prototype must have similar weights. That is:

[0100]

[0101] In the formula: γ — density; P — prototype; M — model.

[0102] Under the influence of gravity and internal stress, the dominant similarity criterion for the deformation and failure process of rocks is:

[0103]

[0104] Within the elastic range, both the model and the prototype should satisfy the differential equilibrium equations, and the following relationships should be satisfied among the similarity constants:

[0105] a σ =a γ a L

[0106] In the formula: σ P σ M —Stress in physical prototypes and models; a σ —Stress (strength) similarity constant.

[0107] Based on comprehensive analysis, the geometric similarity ratio of the experimental model was determined to be αL = 100:1; the bulk density similarity ratio was determined to be αγ = 1.6:1.

[0108] The model is required to have similar motion at all corresponding points to the entity, meaning the velocity, acceleration, and motion time of each corresponding point must be proportional. Therefore, the time similarity ratio must be constant. 1 = 10:1.

[0109] Based on the compressive strength parameters of the original strata rocks, the strength index of the model material is calculated layer by layer, a σ =a L ·a γ =160:1. The transformation relationship of the strength parameters between the prototype and the model can be derived from the dominant similarity criterion, namely:

[0110]

[0111] In the formula: [σ c ] H 、[σ c ] M —These represent the uniaxial compressive strengths of the prototype material and the model material, respectively;

[0112] L H L M —These are the length dimensions of the prototype material and the model material, respectively;

[0113] γ H γ M — These are the bulk density of the prototype material and the model material, respectively.

[0114] Based on the above relationships, the thickness L of different rock layers in the model can be calculated. M Uniaxial compressive strength of soil and rock [σ c ] M and bulk density γ M The density and compressive strength parameters of the prototype and model materials are shown in Table 2.

[0115] Table 2. Bulk density and compressive strength of prototype and model materials

[0116]

[0117] 2.3) Accurately calculate the proportion of materials used in the three-dimensional model based on the requirements of the physical and mechanical properties parameters of the model materials.

[0118] The experimental aggregate used was clean fine sand, and the binder used was lime, gypsum and water. Based on the physical and mechanical properties of the actual rock and soil of the slope, the material ratio of each rock layer in the model was determined through uniform experiments.

[0119] The basic requirements that the physical and mechanical properties of similar materials used in constructing experimental models should meet are as follows:

[0120] (1) The main mechanical properties are similar to those of the simulated rock strata or structure. For example, when simulating the failure process, the uniaxial compressive and tensile strengths of the similar materials should be similar to those of the prototype material;

[0121] (2) The mechanical properties of the material are stable during the experiment and are not easily affected by external conditions;

[0122] (3) By changing the material ratio, certain properties of the materials can be adjusted to meet the needs of similar conditions;

[0123] (4) It is easy to make, has a short solidification time, and has a wide range of material sources.

[0124] Based on the actual engineering geological conditions of the open-pit mine, the components of the similar simulation material were selected. Similar simulation materials are typically composed of several materials, and the raw materials can be divided into aggregates and cementing materials. Aggregates constitute a large proportion of the similar material, and their physical and mechanical properties have a significant impact on the properties of the similar material. Aggregates mainly include sand, tailings, clay, iron powder, sawdust, and diatomaceous earth; clean fine sand was used in this experiment. Cementing materials are the dominant component determining the properties of the similar material, and their mechanical properties largely determine the mechanical properties of the similar material. Commonly used cementing materials include gypsum, cement, lime, water glass, calcium carbonate, and resin. Based on the experimental and geological composition, lime and gypsum were used as cementing materials in this experiment. By calculating the physical and mechanical property parameters of the model soil and rock mass, aggregate and cementing material mix proportions were selected for a mix proportion consistent with the calculated parameters, thus meeting the similarity requirements.

[0125] With the physical and mechanical properties of the rock and soil on the open-pit mine slope as the target, the proportion of similar materials was studied by uniform test, and the proportion of similar materials for each model is shown in Table 3.

[0126] Table 3. Material ratio for similar experimental models

[0127]

[0128]

[0129] The layer thickness and layer material composition of the project model are shown in Tables 4, 5, and 6.

[0130] Table 4. Statistical Table of Layer Thickness in Model

[0131] Serial Number Stratigraphy and Lithology Layer thickness (cm) × number of layers Total thickness of each layer (cm) Cumulative thickness (cm) 1 sandstone 2×8 10 107.4 2 Sandy mudstone 2×15 20 97.4 3 fine sandstone 2.8×10 15.4 77.4 4 4-2 intermediate coal seam 2.6×12 4.6 62 5 Sandy mudstone 2×15 20 57.4 6 5-1 Upper Coal Seam 2×5 2 37.4 7 siltstone 2.8×7 7.8 35.4 8 Sandy mudstone 2.3×4 2.6 27.6 9 5-1 coal seam 2.8×5 5.0 25 10 Sandy mudstone 2×13 20 20

[0132] Table 5. Materials needed for the 3D model

[0133]

[0134] Table 6. Material list for the two-dimensional model

[0135]

[0136] The experimental materials and model-making data above were obtained from theoretical proportions calculated using uniform experiments on similar materials based on the actual conditions of a certain mining area. Actual experiments are often complex and uncertain. While theoretical proportions provide an important reference basis for the experiments, in practice, to obtain more accurate experimental results and to further reveal the relevant mechanisms, the proportions will be flexibly adjusted and optimized based on the actual observed experimental phenomena.

[0137] The geological parameters of the model were confirmed based on borehole data, geological profiles, and physical and mechanical properties of coal and rock strata.

[0138] The physical and mechanical parameters of materials, such as compressive strength, shear strength, elastic modulus, and Poisson's ratio, are determined to provide basic data for mechanical analysis during the experiment.

[0139] Based on the physical and mechanical properties of the actual soil and rock mass of the slope, the material ratio of each rock layer in the model was determined through uniform experiments.

[0140] 2.4) Before excavation, design the excavation sequence and parameters, confirm the overall slope angle of the excavation slope, and confirm the physical dimensions of each mining operation in the project based on the actual mining conditions in the mining area.

[0141] The physical dimensions of each mining operation include parameters such as the number of mining chambers, the size of the reserved coal pillars, the size of the mining chambers, the excavation depth, and the mining construction sequence.

[0142] 2.5) Monitoring Parameter Design

[0143] Before the experiment begins, it is necessary to confirm the relevant monitoring parameters in advance according to the monitoring requirements of the mining tunnel construction process, including the number and installation location of pressure sensors, the number and location of surface displacement monitoring targets, so as to provide technical support for the later monitoring of slope displacement and internal pressure changes.

[0144] The similarity material simulation experiment method is based on similarity theory and dimensional analysis. First, a scaled-down model of the geological body under study is constructed according to a certain similarity ratio. Then, on-site excavation is simulated, and mechanical phenomena and laws such as displacement, stress, and strain are observed. Finally, the deformation law of the rock mass is obtained by analyzing the deformation and failure process and characteristics of the model. This method is an important method for studying rock strata movement induced by underground mining. It can accurately reproduce the deformation and failure process of the entire geological body and accurately reflect the occurrence and development of discontinuous deformation of the rock mass. It has the characteristics of clear and direct experimental results, short experimental cycle, and rapid effectiveness. The principles followed by this type of experiment are very complex and rigorous. As a means of studying mining engineering, the principles followed vary depending on the research purpose. Because it is a qualitative simulation, strict adherence to various similarity relationships is not required during the simulation process; only the satisfaction of the main similarity constants is needed to achieve the experimental purpose. Therefore, it has become a widely used experimental method.

[0145] Step 3: Construction of the simulation experiment model

[0146] Model making stage: Similar materials are prepared and stacked according to the predetermined model shape and size, and compacted in the closed space of the test bench to ensure the density and uniformity of the model and simulate the actual geological conditions.

[0147] According to similarity theory, the experimental model and the physical prototype need to satisfy three similarity laws. According to the first law of similarity, to simulate the deformation and failure process of the end-face mining slope, there should be three aspects of similarity between the model and the prototype: geometric similarity, kinematic similarity, and dynamic similarity.

[0148] According to the experimental content of this invention, corresponding test benches are designed and built for the three-dimensional simulation experiment and the two-dimensional simulation experiment respectively. The test bench mainly consists of an experimental platform, an experimental area, a surrounding constraint device, a tunnel construction device, etc.

[0149] 3.1) Laying out the model

[0150] On two-dimensional and three-dimensional test benches, the model is laid out layer by layer in near-horizontal manner according to the geological distribution characteristics and similar material ratios, through processes such as mixing, spreading and compacting. If the experiment requires the installation of pressure sensors above the coal seam during the laying of the strata, the sensors need to be installed and placed according to the pressure sensor layout plan.

[0151] 3.2) Slope excavation

[0152] After the model material reaches the predetermined strength, the constraints on the front of the three-dimensional model and the front and rear sides of the two-dimensional model are first released. Then, open-pit excavation is carried out, and the depth is reduced to the bottom elevation of the coal seam according to the designed slope parameters to form the end slope.

[0153] 3.3) Surface displacement monitoring target layout

[0154] After the end slope is formed, displacement monitoring targets are set up on the surface of the two-dimensional and three-dimensional models according to the pre-determined monitoring target layout plan. The displacement monitoring grid of the two-dimensional model is set up on the side surface of the two-dimensional model, and the target points of the three-dimensional model are set up on the surface of each platform of the slope and the ground surface of the outer edge of the slope.

[0155] Step 4: Simulation of the entire tunnel construction process

[0156] The open-pit excavation process was simulated using a fixed-axis punching and cutting system on both 3D and 2D models. Following the designed excavation sequence and parameters, the construction of the tunnel complex was simulated step-by-step. During the construction process, the excavation rate and dimensions were precisely controlled to ensure consistency with actual working conditions.

[0157] Experimental loading and observation phase: According to the experimental objective, appropriate loads and boundary conditions are applied, such as simulating roof pressure and lateral surrounding rock pressure. Using sensors, cameras, and other observation methods, the deformation, stress distribution, and failure mode of the model during the loading process are monitored in real time, and experimental phenomena are recorded.

[0158] 4.1) Carry out tunnel construction and inter-tunnel filling.

[0159] This tunneling experiment was designed to mine and fill two coal seams: the 5-1 coal seam and the 4-2 intermediate coal seam.

[0160] The tunneling operation adopts an upward mining method, first mining the bottom 5-1 coal seam, and then mining and backfilling the 4-2 middle coal seam after the mining and backfilling are completed.

[0161] Among them, the 5-1 coal seam is designed to be mined with 23 roadways, with roadway dimensions of 50mm×50mm and coal pillar dimensions of 65mm×65mm;

[0162] The 4-2 coal seam is designed to have 25 roadways, with roadway dimensions of 45mm × 45mm and coal pillar dimensions of 58mm × 58mm.

[0163] 4.2) Construction and backfilling of coal seam roadways

[0164] For example, after installing the tunneling equipment, select a 50mm×50mm tunneling head, and start from the lower left of the model, tunneling the roadway from left to right in a single advance distance of 10cm, excavating a total of 23 roadways, with coal pillars measuring 65mm×65mm.

[0165] Before tunneling, a drone and a 3D laser scanner were used for monitoring to record the initial state of the model.

[0166] When the third tunnel is excavated, the first tunnel is filled. The filling material is transported to the bottom of the excavated tunnel using a filling device, and filling is carried out from the end of the tunnel at a rate of 5 cm per step up to the entrance.

[0167] Following the steps outlined above, continue excavating and intermittently filling the roadways until the mining and filling of all roadways in the 5-1 coal seam are completed.

[0168] Every five tunnels excavated are monitored by drones and 3D laser scanners, with hourly fixed-point photography and pressure sensor monitoring throughout the process.

[0169] Industrial cameras were installed in two roadways in the middle of the 5-1 coal seam to monitor changes in the roadways in real time. Endoscopic cameras were used to monitor the time, distance, and status of changes inside the roadways in a regular manner and to record the data.

[0170] 4.3) Construction of spoil heap and preparation for coal seam construction

[0171] After the construction of coal seam 5-1 is completed, a soil removal platform is formed at the ground surface in front of the model. The platform is about 30cm wide. As the platform is gradually raised, a baffle is installed in front of the test bench to ensure the stability of the platform. Construction is stopped when the platform elevation reaches the bottom elevation of the middle coal seam of coal seam 4-2, and the filling material for coal seam 4-2 is piled on the platform.

[0172] 4.4) Construction and backfilling of the intermediate coal seam roadways.

[0173] The tunneling head was replaced with a 45mm×45mm head, and the tunnels were excavated from left to right in the same way as the 5-1 coal seam, for a total of 25 tunnels. The coal pillar size was 58mm×58mm.

[0174] Repeat the 5-1 coal seam intermittent filling steps, using the filling device to transport the filling material to the bottom of the excavated roadway, and gradually advance the filling upward from the bottom of the tunnel, with each filling thickness being about 5cm.

[0175] Until the mining and filling of all roadways in the 4-2 coal seam are completed.

[0176] Similarly, every five tunnels excavated are monitored by drones and 3D laser scanners, with fixed-point photography taken every hour throughout the process.

[0177] When pre-installing pressure sensors, the design plan was strictly followed, and potential key locations were precisely located and arranged. The sensors were placed 2cm above coal pillar No. 9 in coal seam 5-1 and coal pillar No. 10 in coal seam 4-2. For coal seam 5-1, starting 15cm from the entrance, 10 pressure sensors were evenly arranged at fixed intervals of 15cm along the direction of the coal pillar until the pressure monitoring points for that coal seam were complete. For coal seam 4-2, similarly, starting 15cm from the entrance, 10 pressure sensors were systematically placed at intervals of 10cm to ensure comprehensive coverage and a reasonable layout, providing a reliable guarantee for accurate monitoring of pressure changes in the coal pillars.

[0178] 4.5) The entire construction process is continuously monitored by a combination of pressure sensors, 3D laser scanners, UAV close-range photogrammetry, and endoscopic camera monitoring equipment. The monitoring plan is shown in Table 7 below.

[0179] Table 7 Data Table of Experimental Process Monitoring Plan

[0180]

[0181]

[0182] Step 5: A comprehensive three-dimensional monitoring of the entire process of deformation and damage of the end-face mining slope is achieved by using a panoramic phase 3D laser scanner, a high-resolution digital camera, and a deep space micro-imaging system.

[0183] 1) During the experiment, a three-dimensional laser scanner was used to perform panoramic scanning measurements on the surface of the three-dimensional model slope three times. The scanning times were before the construction of the mining tunnel, after the completion of two mining tunnels and the deformation stabilized, and after the completion of all mining tunnel construction and the deformation stabilized.

[0184] 2) High-resolution digital cameras are used to acquire high-definition images of two-dimensional and three-dimensional models from different angles, and finally high-resolution orthophotos of the model surface are obtained. The frequency of high-definition image acquisition is mainly determined in conjunction with the failure process of the overlying rock mass supporting the coal pillar.

[0185] 3) Once each mining tunnel reaches the predetermined depth, immediately install a deep space micro-imaging system to track and monitor the failure and instability process of the inter-tunnel supporting coal pillars, and obtain the starting position of the collapse and failure of the supporting coal pillars of the mining tunnel group and its chain failure characteristics.

[0186] 4) After the construction and filling are completed, continuous monitoring data will be collected, and three-dimensional data monitoring will be carried out 2-3 times a day;

[0187] 5.1) Stress monitoring of supporting coal pillars

[0188] After setting up the stress monitoring points, ensure that each stress sensor remains on throughout the experiment. After each experiment, archive the data in a dedicated folder.

[0189] After the measurement data is collected and recorded regularly, the historical monitoring data is transmitted and downloaded using the accompanying software. The data is then analyzed and processed to plot curves showing the change of earth pressure over time and the relationship between earth pressure and depth.

[0190] 5.2) Monitoring of slope surface deformation

[0191] Before each simulation of the tunnel construction, intermittent filling, cross-mining and internal drainage, single coal pillar failure and tunnel segment filling in the two-dimensional and three-dimensional experiments, and throughout the entire construction process, it is necessary to use drones equipped with high-definition cameras and stationary three-dimensional laser scanners to collect image data and three-dimensional laser scanning data of the model at various states, save and record the initial state and the three-dimensional spatial information of the model throughout the construction process, for later comparison of slope surface deformation.

[0192] a) Collect 3D data of the slope surface using a 3D model, and 2D data of the slope surface and the outer edge of the slope.

[0193] b) Initial State Scanning Phase

[0194] ① Data Acquisition: Before the experiment, a comprehensive 3D laser scan of the slope was performed to obtain initial point cloud data of the slope. During the scan, it was ensured that the entire slope area was covered, including the top, surface, and toe of the slope, while avoiding blind spots.

[0195] ② Data preprocessing: The initial point cloud data is preprocessed, including noise removal, filtering, and point cloud registration, to obtain a complete point cloud, such as... Figure 7 As shown.

[0196] c) Scanning stage of the tunneling process

[0197] During operations such as tunnel construction, intermittent filling, cross mining and internal drainage, single coal pillar destruction, and segmented tunnel filling, a 3D laser scanner is used regularly to scan the slope at different times to obtain point cloud data at different times and record the model changes before and after key construction nodes (such as excavation and filling). The scanner station settings are kept as consistent as possible with the parameters of the data collected in the initial state.

[0198] d) Perform rapid preprocessing and analysis on the point cloud data acquired in each scan. This mainly includes removing noise points caused by dust, splashes, etc., generated during the tunneling process, identifying and marking collapsed areas, and analyzing the point cloud scanning effect after excavation, such as... Figure 8 As shown.

[0199] 5.3) Oblique photogrammetry of the model surface

[0200] (a) Equipment preparation: Target points were pre-laid on the experimental model's stepped surface, each with an independent number. A DJI Mavic 3 Pro (e.g., [missing information]) was used. Figure 9 As shown, the experimental model monitoring surface was photographed from multiple angles.

[0201] The equipment parameters are shown in Table 8 below:

[0202] Table 8. UAV Equipment Parameters

[0203] Equipment parameters Detailed information Product Type quadcopter Gimbal type Three-axis mechanical gimbal (pitch, roll, yaw) Controllable rotation range Pitch: -90° to 35° Yaw: -5° to 5° Lens configuration Medium telephoto camera: 1 / 1.3-inch CMOS sensor, 48 megapixels, equivalent to 70mm F2.8. Maximum resolution of photos 8064×6048 Sensing system An omnidirectional binocular vision system, supplemented by an infrared sensor on the bottom of the device.

[0204] (b) Monitoring data collection

[0205] 1) Initial state data acquisition

[0206] Using drones equipped with high-definition cameras, the experimental model was photographed from multiple angles, collecting multi-angle image data, such as... Figure 9 As shown, the image data and 3D spatial information in the initial state are recorded. Ensure all target points are within the shooting range for easy post-processing and analysis.

[0207] 2) Construction process monitoring

[0208] Before operations such as tunnel construction, intermittent backfilling, cross-mining and internal drainage, single coal pillar destruction, and segmented tunnel backfilling, regular drone aerial photography is conducted to collect image data and 3D spatial information, recording model changes before and after key construction nodes (such as excavation and backfilling). The flight path for data collection is kept as consistent as possible with the parameters of the data collected in the initial state, such as... Figure 10 As shown.

[0209] 3) Data collection frequency and schedule

[0210] The frequency of data collection should be arranged reasonably according to the construction progress and needs. Under normal circumstances, a comprehensive data collection should be carried out at least once a day.

[0211] For critical construction phases, the frequency of data collection is increased, with data collection conducted every five tunnels to ensure that important deformation moments are not missed.

[0212] 4) Image modeling

[0213] Reality modeling software is used to construct a current reality model from captured oblique images, such as... Figure 11 As shown.

[0214] 5.4) Real-time on-site video monitoring

[0215] When the tunnel excavation work reaches the middle of the test block, real-time monitoring of the tunnel interior is required.

[0216] In specific project implementation, an optional design testing method is to place an industrial camera in the middle and rear of the roadway after the designed testing roadway is excavated. This is to focus on observing the deformation inside the roadway and to fully display the impact of coal pillars and roof on the roadway interior when excavating adjacent roadways.

[0217] Industrial endoscopes are used to monitor for displacement, collapse, and other events within tunnels. The industrial endoscope displays information synchronously with video surveillance, allowing real-time observation of the overall appearance of the experimental model and changes within the tunnel. Figure 12 .

[0218] 5.5) Deformation Analysis Method

[0219] Deformation patterns were analyzed by comparing the overall model across multiple phases and by comparing relative point displacements.

[0220] The three-dimensional reality model constructed by oblique photogrammetry of multiple key construction nodes is compared with the deformation data of the three-dimensional reality model in the initial state. Two three-dimensional data are selected each time, with the initial state set as the reference model and the subsequent construction node model set as the analysis model, so as to obtain the three-dimensional surface deformation data of each key construction node.

[0221] Several target coordinate points were selected at key locations such as the upper, middle, and lower parts of the slope body in the three-dimensional real-scene model formed by multiple monitoring and data collection as monitoring objects to monitor the evolution of horizontal stress in the rock mass of the upper slope of the mining area.

[0222] Select the coordinates of the points and input them into the database. The data analysis platform will then output the curves showing the changes in horizontal and vertical displacements.

[0223] Based on real-time monitoring data and observations during the experiment, an in-depth analysis and summary of the slope stability and collapse mechanism were conducted.

[0224] Step Six: Model Dismantling

[0225] After the experiment is completed and the data is confirmed to be correct, the model is dismantled and the waste is disposed of.

[0226] Experiment Completion and Dismantling Phase: After completing the experimental loading, the experimental data are organized and analyzed. The overlapping constraint side plates and vertical connecting columns are removed, the experimental model materials are cleaned, and the test bench is maintained and serviced to prepare for the next experiment.

[0227] The working principle of the physical simulation experiment method for slope deformation and instability induced by coal recovery from coal embankment in open-pit mines, as described in this invention, is described below:

[0228] During the operation, the directional sleeve of the tunneling rod is first installed and fixed at a known position on the simulation test platform. Then, flange linear bearings are installed inside the holes of the directional sleeve, with the bearing hole diameter matching the diameter of the galvanized impact shovel rod. The galvanized shovel rod is inserted through the flange linear bearings inside the holes of bracket 1 on the test platform and separately symmetrically mounted bracket 2, and fixed by the flange linear bearings to ensure that the shovel rod does not rotate but can only move freely back and forth along its axis. Then, the appropriate punching shovel head is selected according to the tunnel size required for the experiment and installed at the front end of the galvanized impact shovel rod. By adjusting the position and angle of the directional sleeve of the tunneling rod, the height and direction of tunneling can be controlled. During the sequential tunneling construction of the simulated mining tunnel, the punching shovel head is advanced forward under the drive of the galvanized impact shovel rod. Due to the rigidity of the galvanized impact shovel rod and the constraint of the flange linear bearings inside the holes, the punching shovel head can tunnel stably along a straight path, thus ensuring that the construction mining tunnel is straight and regular. After the experiment, the components can be easily disassembled for cleaning, maintenance, or replacement, in preparation for the next experiment.

[0229] Among them, linear guidance: the flange linear bearing is matched with the rigid impact shovel galvanized rod to limit lateral displacement;

[0230] The tunneling device of this invention can utilize a circular or other polygonal shape for the punching head to adapt to different tunneling requirements. For the material of the galvanized shovel rod, in addition to a rigid linear optical shaft, other high-strength, high-rigidity alloy materials can be selected. In the fabrication of the tunneling rod directional sleeve, in addition to galvanized channel steel, stainless steel or other materials with moisture-proof and corrosion-resistant properties can also be used. Furthermore, the entire tunneling device can be designed as a modular structure, facilitating combination and expansion according to different experimental requirements, such as adding a tunneling power unit or an automated control system, to achieve more complex and precise tunneling operations.

[0231] In the implementation of the physical simulation experiment method for slope deformation and instability induced by coal recovery from open-pit mine side slopes according to the present invention, the following alternative embodiments can be made:

[0232] Alternative Model Materials: In addition to the model materials mentioned in this invention, such as quartz sand, binders, fine sand, and plaster, other similar materials can be explored to simulate soil and rock masses. For example, glass beads of different particle sizes can be mixed with appropriate amounts of resin materials. By adjusting the particle size distribution of the glass beads and the resin content, the mechanical properties of the model material can be controlled to meet different experimental requirements. Alternatively, synthetic polymer materials can be used, and their strength, deformation modulus, and other properties can be adjusted by changing their molecular structure and composition.

[0233] Alternative Monitoring Methods: In terms of monitoring, other advanced monitoring technologies can be adopted to replace or supplement existing monitoring methods. For example, digital image correlation (DIC) technology can be introduced to replace or combine with three-dimensional laser scanning and oblique photogrammetry to conduct a more detailed analysis of slope surface deformation.

[0234] Experimental Procedure Substitution: In experimental procedures, some steps can be adjusted or substituted according to actual research needs. For example, in a three-dimensional model experiment, the sequence or spacing of tunnel construction can be changed to simulate the impact of different mining techniques on slope stability; or in a two-dimensional model experiment, the shape and size of the coal pillar can be adjusted to study its control effect on slope stress and deformation. Simultaneously, during the data acquisition phase, the number and location of monitoring points can be increased or decreased to adapt to different research focuses.

[0235] The physical simulation experiment method of the present invention for inducing slope deformation and instability caused by coal recovery from coal embankment in open-pit mines produces the following effects:

[0236] This invention comprehensively reveals the deformation and instability mechanism of slopes: by simultaneously conducting two-dimensional and three-dimensional model experiments, combined with multiple monitoring methods, it can comprehensively and accurately reveal the deformation and instability mechanism of slopes during coal recovery from coal seams in open-pit mines. Two-dimensional model experiments can clearly demonstrate the deformation characteristics and stress distribution of the slope in a plane, while three-dimensional model experiments can realistically reflect the three-dimensional geological structure and internal failure process of the slope. The two complement and verify each other, providing richer information for a deeper understanding of slope instability mechanisms.

[0237] This invention improves the accuracy of slope stability prediction: Based on the experimental method of this invention, more comprehensive and accurate data on slope deformation and failure can be obtained, thereby establishing a more realistic slope stability prediction model. Through analysis of the experimental data, the stability state of slopes under different coal mining and recovery conditions can be predicted more accurately, providing a scientific basis for formulating reasonable slope stability control measures.

[0238] This invention optimizes coal recovery schemes by conducting simulation experiments on different coal recovery processes (such as tunnel construction and backfilling operations) to study their impact on slope stability, thereby providing guidance for optimizing coal recovery schemes. For example, it determines reasonable parameters such as tunnel spacing, backfilling time, and backfilling materials to improve the coal recovery rate while ensuring slope stability.

[0239] This invention reduces safety risks in mine production: The research findings of this invention help identify potential hazardous areas and critical stages of slope deformation and instability in advance, providing early warning information for mine production safety management. By taking corresponding stability control measures, the probability of slope instability accidents can be effectively reduced, ensuring the safety of mine personnel and the normal operation of equipment.

[0240] The simulation experimental device designed in the physical simulation experimental method for slope deformation and instability induced by coal recovery from open-pit mine side slopes according to the present invention can also produce the following technical effects:

[0241] 1. Improve tunneling stability: By using a rigid linear optical shaft as the galvanized shovel rod of the impact shovel, and in conjunction with a high-precision flange linear bearing, the stability and straightness of the simulated mining tunnel's sequential tunneling process are ensured, avoiding experimental errors caused by unstable tunneling lines and improving the reliability of experimental results.

[0242] 2. Enhanced applicability: Two different sizes of square punching heads were designed to adapt to similar material models of different sizes and material ratios, meet diverse experimental needs, and expand the application range of the device.

[0243] 3. Convenient installation and disassembly: The components of the device are connected by bolts, making disassembly and installation very convenient. This saves time in experimental preparation and organization, improves experimental efficiency, and also facilitates the maintenance and replacement of components during the experiment.

[0244] 4. Extended service life: The tunneling rod directional sleeve is made of galvanized channel steel, which has moisture-proof and corrosion-proof properties. It can be used in humid experimental environments, is not easy to rust and corrode, extends the service life of the device, and reduces the cost of use.

[0245] 4) Excavation sequence and parameter design

[0246] Before excavation, the excavation sequence and parameters are designed to confirm the overall slope angle of the excavation slope. At the same time, based on the actual mining conditions in the mining area, parameters such as the number of mining chambers, the size of the reserved coal pillars, the size of the mining chambers, the excavation depth, and the mining construction sequence are confirmed.

[0247] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A physical simulation experimental method for slope deformation and instability induced by coal recovery from coal embankment in open-pit mines, characterized in that, Includes the following steps: Step 1: Select the experimental research unit and prepare the simulation experimental setup; Step two, design of experimental parameters for tunnel construction; specifically including: 2.1) Study the engineering geological conditions and mining conditions of the slope, and confirm the stratigraphic parameters for model laying based on borehole data, geological profiles and physical and mechanical properties of coal and rock strata; 2.2) Indoor tests were conducted on the three-dimensional model materials and the two-dimensional model materials, including direct shear tests, triaxial compression tests, and uniaxial compressive strength tests, in order to determine the physical and mechanical property parameters of the model materials; 2.3) Based on the requirements of the physical and mechanical properties of the model materials, accurately calculate the material ratio of the three-dimensional model materials; the ratio of quartz sand to binder. 2.4) Before excavation, design the excavation sequence and parameters, confirm the overall slope angle of the excavated slope, and confirm the physical dimensions of each mining operation in the project based on the actual mining conditions in the mining area. 2.5) Based on the monitoring requirements of the mining tunnel construction process, confirm the relevant monitoring parameters in advance to provide technical support for later monitoring of slope displacement and internal pressure changes; Step 3: Prepare and stack similar materials according to the predetermined model shape and size, and compact them in the closed space of the test bench to ensure the density and uniformity of the model and simulate the actual geological conditions. Step four involves simulating the open-pit excavation process using a fixed-axis punching and cutting system on both 3D and 2D models. Following the designed excavation sequence and parameters, the construction of the tunnel complex is simulated step by step. During the construction process, the excavation rate and dimensions are precisely controlled to ensure consistency with actual working conditions. 4.1) Carry out tunnel construction and intermittent filling; 4.2) Carry out coal seam roadway construction and backfilling; 4.3) Construct a spoil heap and prepare for coal seam construction; 4.4) Construction and backfilling of the intermediate coal seam roadways; The entire construction process is continuously monitored by a combination of pressure sensors, 3D laser scanners, UAV close-range photogrammetry, and endoscopic camera monitoring equipment. Step 5: A comprehensive three-dimensional monitoring of the entire process of deformation and damage of the end-face mining slope is achieved by using a panoramic phase 3D laser scanner, a high-resolution digital camera, and a deep space micro-imaging system.

2. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine as described in claim 1, characterized in that, Step one specifically includes: 1.1) Select a wound area as the research unit to confirm the geometric similarity ratio of the simulation experiment and the scope of the test area; 1.2) The prepared tunneling device, the tunneling device mainly consists of a tunneling rod directional sleeve and a punching shovel, the tunneling rod directional sleeve includes the present invention tunneling device mainly consists of a tunneling rod directional sleeve and a punching shovel, the tunneling rod directional sleeve includes a gold digging rod quantitative sleeve bracket (1) fixed on the test bench, and a gold digging rod directional sleeve bracket (2) erected separately and symmetrically, wherein multiple bracket slots (3) are provided at intervals on the gold digging rod quantitative sleeve bracket (1) and the gold digging rod directional sleeve bracket (2); The punching tool includes a galvanized shovel bar (5), a detachable punching head (6), and an operating handle (7); 1.3) Using this device, a series of mining tunnels perpendicular to the slope direction can be constructed at any specified position on the front of the model into the interior of the slope.

3. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine, as described in claim 1, is characterized in that... In step two, The geometric similarity ratio of the experimental model is α L =100:1; the bulk density similarity ratio is α γ =1.6:1; Based on the compressive strength parameters of the original strata rocks, the strength index of the model material is calculated layer by layer, a σ =a L ·a γ =160:

1. The transformation relationship of the strength parameters between the prototype and the model can be derived from the dominant similarity criterion: In the formula: [σ c ] H 、[σ c ] M —These represent the uniaxial compressive strengths of the prototype material and the model material, respectively; L H L M —These are the length dimensions of the prototype material and the model material, respectively; γ H γ M — These are the bulk density of the prototype material and the model material, respectively.

4. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine as described in claim 1, characterized in that, Step three includes: 3.1) On two-dimensional and three-dimensional test benches, the model is laid out layer by layer in near-horizontal manner according to the geological distribution characteristics and similar material ratios, through processes such as mixing, spreading and compacting. 3.2) After the model material reaches the predetermined strength, first release the constraints on the front of the three-dimensional model and the front and rear sides of the two-dimensional model, and then carry out open-pit excavation, and reduce the depth to the bottom elevation of the coal seam according to the designed slope parameters to form the end slope. 3.3) Based on the pre-determined target layout plan, displacement monitoring targets are laid out on the surfaces of the two-dimensional and three-dimensional models respectively. The displacement monitoring grid of the two-dimensional model is laid out on the side surface of the two-dimensional model, and the target points of the three-dimensional model are laid out on the surface of each platform of the slope and the outer edge of the slope surface.

5. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine as described in claim 1, characterized in that, Step five includes: 5.1) Regularly record the measurement data. After the data collection is completed, use the supporting software to transmit historical monitoring data and download the data, and analyze and process the data. 5.2) Before each process simulation of tunnel construction, intermittent filling, cross mining and internal drainage, single coal pillar failure and tunnel segment filling in the two-dimensional and three-dimensional experiments, and throughout the entire construction process, it is necessary to use a drone equipped with a high-definition camera and a stationary three-dimensional laser scanner to collect image data and three-dimensional laser scanning data of the model at various states, save and record the initial state and the three-dimensional spatial information of the model throughout the construction process, for later comparison of slope surface deformation; 5.3) Target points were pre-set on the stepped surface of the experimental model, and each target point was independently numbered to take multi-angle photos of the experimental model monitoring surface. 5.4) When the tunnel excavation work reaches the middle of the test block, real-time monitoring of the tunnel interior is required. 5.5) Analyze the deformation pattern by comparing the overall model across multiple periods and the relative point displacement.

6. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine, as described in claim 5, is characterized in that... Step 5.2) includes: a) Collect 3D data of the slope surface from the 3D model, and 2D data of the slope surface and the outer edge of the slope. b) Initial state scan phase: ① Data Acquisition: Before the experiment, a comprehensive 3D laser scan of the slope was performed to obtain initial point cloud data of the slope. During the scan, it was ensured that the entire slope area was covered, while avoiding blind spots. ② Data preprocessing: The collected initial point cloud data is preprocessed to obtain a complete point cloud. c) During the construction of tunnels, intermittent backfilling, cross-mining and internal drainage, single coal pillar destruction, and segmented backfilling of tunnels, a 3D laser scanner is used periodically to perform timed scans to obtain point cloud data of the slope at different times and record the model changes before and after key construction nodes. d) Perform rapid preprocessing and analysis on the point cloud data acquired in each scan, and identify and mark the collapsed areas. The point cloud scanning effect after excavation.

7. The physical simulation experimental method for slope deformation and instability induced by coal recovery from coal pile-up at the side of an open-pit mine as described in claim 1, characterized in that, The method also includes: Step Six: After the experiment is completed and the data is confirmed to be correct, dismantle the model and dispose of the waste.

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