Visual modeling and analysis method for in-situ fluidized mining of coal containing fault structure

Abstract

The invention discloses a visual modeling and analysis method for in-situ fluidized mining of coal containing a fault structure, and relates to the technical field of numerical modeling and analys.The method comprises the steps that firstly, a Z-shaped progressive fluidized mining configuration is configured, and a multi-physics field coupling numerical simulation system is constructed; geologic structure parameterization is realized through multi-source geologic data fusion, a geomechanical prototype is constructed, and constitutive parameter mapping is completed; then, a three-dimensional geology-engineering integrated model is built and imported into a numerical platform after fine grid division, the whole mining process is simulated, and mechanical response data are collected; finally, the critical state of goaf instability is identified through multi-criterion coupling, and a basis is provided for filling opportunity and strength design. Accurate coupling of complex geology and dynamic mining is achieved, asymptotic damage of surrounding rock of the goaf can be actively monitored, safety and efficiency of deep coal resource mining are effectively improved, and powerful technical support is provided for intelligent and unmanned mining.

Description

Technical Field

[0001] This invention relates to the field of numerical modeling and analysis technology, and more specifically to a visualization modeling and analysis method for in-situ fluidized coal mining with fault structures. Background Technology

[0002] The mining environment of deep coal and rock masses is extremely complex, facing severe challenges not only from the "three highs and one disturbance" (high ground pressure, high ground temperature, high osmotic pressure, and mining disturbance), but also from the constraints imposed by geological structures. Especially near weak structural planes such as fault zones, traditional mining methods are highly susceptible to major disasters such as rock bursts, large deformations, and even water inrushes, making it difficult to overcome the "limit depth." The concept of "in-situ fluidized bed mining of deep coal resources" provides a new approach to fundamentally solving the safety and environmental challenges of deep mining. However, achieving in-situ fluidized bed mining of deep coal still faces many technical and geological challenges, and the relevant theoretical systems and engineering practices are still immature.

[0003] Significant fault zones are prevalent in deep strata, typically characterized by fractured rock masses, dense structural planes, and uneven stress distribution, significantly increasing the difficulty of controlling in-situ fluidization of coal and rock masses. The presence of fault zones disrupts the continuity and overall stability of coal seams, easily inducing uncontrollable fracture propagation, rock mass movement, and even surrounding rock instability during fluidized mining, thereby affecting mining efficiency and threatening operational safety. On the one hand, traditional geological modeling methods are mostly based on homogeneous or simplified heterogeneous assumptions, making it difficult to accurately characterize the discontinuous structural features within fault zones. Furthermore, when dealing with highly irregular geometries formed by the intersection of faults and coal seams, conventional mesh generation is prone to producing distorted units, leading to numerical calculation non-convergence. On the other hand, existing mining models mainly target areas with good integrity or relatively stable geological conditions. A systematic technical framework and mature mining path planning are still lacking for achieving stable and controllable in-situ fluidized coal mining in fault-affected areas. In addition, existing monitoring methods often overlook the malignant expansion of the "butterfly-shaped" plastic zone and the principal stress deflection mechanism unique to deep high-stress fields, making it difficult to capture critical precursor information of dynamic disasters.

[0004] Especially for the path selection in deep fluidized bed mining, traditional straight-line long-distance advances easily form massive, continuous "pressure arches" in the overburden, leading to large-scale roof collapses or triggering fault activation. In contrast, the "Z-shaped" path has unique mining advantages. The Z-shaped path essentially constitutes a spatiotemporal "staggered mining" mode, which spatially divides the large-span pressure arch of the overburden into several controlled small-span arches and utilizes unmined coal pillars as temporary support points, effectively curbing the malignant expansion and connection of the plastic zone. However, existing numerical modeling methods cannot yet achieve a refined simulation of the dynamic interaction between this complex spatiotemporal path and faults.

[0005] Therefore, how to construct a visual modeling and analysis method for in-situ fluidized coal mining with fault structures is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a visualization modeling and analysis method for in-situ fluidized coal mining with fault structures, in order to solve the problems existing in the background technology.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures, comprising: S1, Configure the geometric parameters and topological path of the zigzag progressive fluidized bed mining in the numerical simulation system; S2, acquire borehole data and geological profile of the target mining area, extract coal seam roof and floor elevation data and fault zone geometric feature parameters, and generate a spatial vector dataset describing the geological structure; S3. Based on the spatial vector dataset, construct a geometric entity model of the rock strata and fault zone, map the rock mechanics parameters measured in the laboratory to the corresponding geometric entity, set the contact relationship between the fault zone and the coal and rock strata, and generate a geomechanical prototype containing material properties. S4. Import the geomechanical prototype into the three-dimensional modeling software, use linear array solid cuboid units to generate several independent mining unit entities with equal geometric dimensions to be pre-embedded in the mining area, and number each independent mining unit entity according to the topological path to construct a three-dimensional geological-engineering composite model containing a preset mining sequence. S5. Perform geometric topology repair on the three-dimensional geological-engineering composite model. First, generate a surface mesh dominated by quadrilaterals at the model boundary, and then use a remeshing algorithm to generate an unstructured volume mesh dominated by hexahedrons. S6. Import the unstructured body mesh into the numerical analysis platform, establish mining unit groups and rock strata groups according to the sequence number, and assign corresponding constitutive models and mechanical parameters respectively; apply displacement boundary conditions and overlying rock strata loads, perform initial geostress field equilibrium calculations until the model reaches steady state, and set up stress and displacement monitoring points in the fault zone and surrounding rock of the goaf. S7. Based on the sequence number of the topological path, the constitutive model of the corresponding mining unit group is changed to an empty model step by step to simulate the fluidized mining process; after the mining calculation balance is achieved at each step, the monitoring data is recorded to construct a full-sequence mechanical response database; S8. Based on the full-sequence mechanical response database, when the current mining sequence is detected to be in an unstable critical state, the sequence is marked as the intervention time for backfilling operation.

[0008] Preferably, S3 specifically includes: using a rock mass quality evaluation system to score the geological strata and fault zones in the mining area to obtain rock mass quality indicators; calculating a strength reduction coefficient based on the rock mass quality indicators; using the strength reduction coefficient to correct the rock mechanics parameters measured in the laboratory to obtain engineering rock mass physical and mechanical parameters; and assigning the engineering rock mass physical and mechanical parameters to the corresponding geometric entity model to complete the parameter mapping from laboratory data to an engineering-scale constitutive model.

[0009] Preferably, S4 specifically includes: S4.1, import the geometric data of the geomechanical prototype generated in step S3 into the 3D modeling software, and reconstruct the 3D entities of the coal seam, roof and floor and fault zone according to the coordinate system. S4.2 Based on the preset Z-shaped mining path parameters, several independent mining unit entities with equal geometric dimensions are generated and pre-embedded in the mining area using linear array solid cuboid units, and each independent block is serialized and numbered. S4.3, use NURBS surface tools to repair the geometric gaps caused by cutting, and ensure that the contact surface topology between the fault zone entity and the coal seam entity is consistent; S4.4 combines the processed coal seam mining unit entities, surrounding rock entities, and fault zone entities to generate a three-dimensional geological-engineering composite model that does not contain geometric overlaps or voids.

[0010] Preferably, S5 specifically includes: S5.1, Use the remeshing tool to repair the boundary surfaces of the three-dimensional geological-engineering composite model and remove debris surfaces and overlapping surfaces; S5.2 Generates a surface mesh dominated by quadrilaterals on the model surface and sets the upper and lower limits of the mesh size parameters; S5.3, Based on the surface mesh, the interior of the model is filled using a volume mesh generation algorithm to generate an unstructured volume mesh dominated by hexahedrons; S5.4 performs mesh quality checks, calculates the Jacobian ratio, removes or repairs distorted elements, and finally exports the mesh file in a format compatible with the numerical computing platform.

[0011] Preferably, S6 specifically includes: S6.1 Import the grid file into the numerical analysis platform and divide each independent mining block into an independent mining group according to the serialization number; S6.2, Call the Mohr-Coulomb constitutive model and assign the rock mass physical and mechanical parameters obtained in step S3 to the rock strata group and fault zone group respectively; S6.3, apply the overlying strata load and boundary displacement constraints, run the calculation until the maximum unbalanced force converges, and obtain the initial geostress field; S6.4, clear the model displacement field to zero, and define historical variable monitoring points at preset positions on the slip surface of the fault zone and the roof of the Z-shaped goaf.

[0012] Preferably, S7 specifically includes: constructing a cyclic mining step, and according to the sequence number i of the zigzag path, i=1, 2, 3, ..., N, executing the following loop in sequence: modifying the constitutive model of the mining unit group numbered i to an empty model, simulating the removal of rock mass; running numerical calculations to the preset equilibrium standard; traversing all monitoring points, extracting and recording the current stress tensor, displacement vector and plastic zone state, and constructing a full-sequence mechanical response database; saving the stress field data file of the current calculation step, until the mining simulation of all preset units is completed.

[0013] Preferably, S8 specifically includes: S8.1, Read the stress tensor data and vertical displacement data of the monitoring point.

[0014] S8.2, Read the state data of the plastic zone, extract the spatial distribution characteristics of shear failure and tensile failure elements, and calculate the volume and expansion morphology of the plastic zone; S8.3, Execute instability detection logic: If stress reversal (i.e., horizontal stress) is detected at a critical point on the top plate... Sudden change exceeding vertical stress Furthermore, if the vertical displacement is greater than 100mm, and the plastic zone of the surrounding rock in the goaf has formed a butterfly-shaped expansion zone and is connected to the fault zone, the current mining sequence is determined to be in an unstable critical state, and this sequence is marked as the intervention time for backfilling operations.

[0015] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a visualization modeling and analysis method for in-situ fluidized coal mining with fault structures. By constructing a pre-embedded Z-shaped geological model, the mining process is directly encoded into the model kernel. Dynamic tracking of the mechanical response of the entire mining process is realized on a multi-physics coupled numerical platform, and the critical point of instability of the surrounding rock in the goaf is accurately located, thereby breaking through the technical bottleneck of the traditional method in terms of adaptability to complex mining processes. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure provided by the present invention; Figure 2 This is a schematic diagram of the overall and partial aspects of the Z-shaped fluidized bed mining method provided by the present invention; Figure 3 This is an overall diagram of the Z-shaped fluidized bed mining method provided by the present invention; Figure 4 This is an overall diagram of the Z-shaped fluidized bed mining model for coal and rock in fault zones provided by the present invention; Figure 5 A partial view of the Z-shaped fluidized bed mining model for coal and rock in fault zones provided by this invention; Figure 6 This is an overall diagram of the Griddle surface meshing model provided by the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention discloses a visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures, such as... Figure 1 As shown, it includes: S1. Configure the geometric parameters and topological path of Z-shaped progressive fluidized bed mining in the numerical simulation system. The geometric parameters include the size of the independent mining unit, the Z-shaped turning interval, and the mining length. The path is defined as a spatial sequence of alternating layered advancement from left to right and from right to left. Specifically, this includes the parameter configuration and path initialization of Z-shaped fluidized bed mining: First, in the conceptual design stage, design the configuration and mechanical path planning of Z-shaped fluidized bed mining in deep coal and rock with fault zones. The core is to actively monitor the progressive failure process of the surrounding rock in the goaf through a Z-shaped fluidized bed mining sequence from left to right and in a step-by-step layered manner. Second, construct a high-precision multi-physics coupled numerical simulation system to systematically and quantitatively identify the critical state of instability of the Z-shaped goaf during the mining process, providing a data foundation for the safety control and intelligent filling strategy of subsequent fluidized bed mining.

[0020] S2, acquire borehole data and geological profile maps of the target mining area, extract coal seam roof and floor elevation data and geometric feature parameters of fault zones. The geometric feature parameters include at least fault dip, dip angle, displacement, and fracture zone width, generating a spatial vector dataset describing the geological structure. Specifically, this includes multi-source data fusion and geological modeling parameterization of the mining area's geological features: based on multi-source geological data of the target mining area, firstly, determine the coal seam occurrence depth, roof and floor lithological sequence, and spatial distribution characteristics; secondly, conduct quantitative analysis of the fault system, including fault zone attitude (dip angle, thickness), spatial distribution, and its relative positional relationship with the coal seam, to achieve parameterized characterization of the geological structure.

[0021] S3. Based on a spatial vector dataset, a geometric entity model of rock strata and fault zones is constructed. Laboratory-measured rock mechanics parameters (including elastic modulus, Poisson's ratio, internal friction angle, and cohesion) are mapped to the corresponding geometric entities. The contact relationship between the fault zone and the coal seam is defined, generating a geomechanical prototype containing material properties. Specifically, this includes the construction of the geomechanical prototype and constitutive mapping of rock mass parameters: Based on the actual geological profile of the mining area, the geometric boundary and stratigraphic framework of the overall model are established, clarifying the fault zone attributes (positive / inverse), geometric parameters, and their spatial relationship with the coal seam. Combining laboratory rock mechanics test data, a rock mass quality evaluation and strength reduction method is used (using the rock mass quality evaluation system RMR or GSI to score each rock strata and fault zone in the mining area to obtain rock mass quality indicators; calculating the strength reduction coefficient based on the rock mass quality indicators; using the strength reduction coefficient to correct the laboratory-measured rock mechanics parameters to obtain engineering rock mass physical and mechanical parameters), determining the engineering rock mass physical and mechanical parameters of kilometer-deep coal seams, and completing the parameter mapping of the constitutive model.

[0022] S4. Import the geomechanical prototype into the three-dimensional modeling software, use linear array solid cuboid units to generate several independent mining unit entities with equal geometric dimensions to be pre-embedded in the mining area, and number each independent mining unit entity according to the Z-shaped path to construct a three-dimensional geological-engineering composite model containing a preset mining sequence; specifically, construct a three-dimensional geological-engineering integrated model: (1) Based on the three-dimensional modeling software Rhino platform, reconstruct the three-dimensional entities of coal seam, roof and floor and fault zone according to the coordinate system; (2) In the coal seam area, according to the preset Z-shaped mining path parameters, use linear array solid cuboid units to generate several independent mining unit entities with equal geometric dimensions to be pre-embedded in the mining area, and number each independent block serially; (3) Use NURBS surface tools to repair the geometric gaps generated by cutting to ensure that the contact surface topology between the fault zone entity and the coal seam entity is consistent; (4) Combine the processed coal seam mining unit entities, surrounding rock entities and fault zone entities to generate a three-dimensional geological-engineering composite model without geometric overlap and holes.

[0023] S5. Based on the composite model, geometric topology repair is performed. First, a quadrilateral-dominated surface mesh is generated at the model boundary. Then, a hexahedron-dominated unstructured volume mesh is generated using a remeshing algorithm and exported as a mesh file format compatible with the numerical computing platform. Specifically, this includes high-fidelity calculation of 4-6-hedron fine mesh generation: (1) Repair the boundary surface of the three-dimensional geological-engineering composite model by using the remeshing tool (Griddle) to remove debris surfaces and overlapping surfaces; (2) Generate a surface mesh dominated by quadrilaterals (Quad) on the model surface and set the upper and lower limits of the mesh size parameters; (3) Based on the surface mesh, fill the interior of the model using a volume mesh generation algorithm to generate an unstructured volume mesh dominated by hexahedrons (Hexahedron); (4) Perform mesh quality checks, calculate the Jacobian ratio, remove or repair distorted units, and finally export as a mesh file format (.f3grid) compatible with the numerical computing platform.

[0024] S6. Import the mesh file into the numerical analysis platform, establish mining unit groups and rock strata groups according to the sequence number, and assign corresponding constitutive models and mechanical parameters respectively; apply displacement boundary conditions and overlying rock loads, perform initial geostress field equilibrium calculations until the model reaches steady state, and set up stress and displacement monitoring points in the fault zone and goaf surrounding rock; specifically, the integration of the numerical simulation platform and the initialization of the multi-field coupling model: (1) Import the mesh file into the numerical analysis platform (FLAC3D), and divide each independent mining block into an independent mining group according to the serial number; (2) Call the Mohr-Coulomb constitutive model, and assign the rock mass physical and mechanical parameters to the rock strata group and fault zone group respectively; (3) Apply overlying rock loads and boundary displacement constraints, run the calculation until the maximum unbalanced force converges, and obtain the initial geostress field; (4) Clear the model displacement field to zero, and define historical variable monitoring points at preset positions on the fault zone slip surface and the Z-shaped goaf roof.

[0025] S7, based on the sequence number of the zigzag path, the constitutive model of the corresponding independent mining unit group is changed to a null model step by step to simulate the fluidized mining process; after the mining calculation balance at each step, the stress tensor, displacement vector and plastic zone state data of the monitoring points are recorded to construct a full-sequence mechanical response database; specifically, it includes numerical simulation and mechanical response acquisition of the zigzag progressive fluidized mining process: constructing a cyclic mining step, according to the sequence number i of the zigzag path (i=1 to N), the following loop is executed in sequence: modify the constitutive model of the mining unit group numbered i to a null model to simulate rock mass removal; run numerical calculations to the preset balance standard; traverse all monitoring points, extract and record the current stress tensor, displacement vector and plastic zone state; save the stress field data file of the current calculation step until the mining simulation of all preset units is completed.

[0026] S8, based on a full-sequence mechanical response database, detects stress reversal (i.e., horizontal stress) at a critical point on the top plate. A sudden change occurs exceeding the vertical stress ( ) and the vertical displacement is greater than 100mm. When the plastic zone of the surrounding rock in the goaf has formed a butterfly-shaped expansion zone and is connected to the fault zone, the current mining sequence is determined to be in an unstable critical state, and the sequence is marked as the intervention time for filling operation. Specifically, it includes multi-criteria coupling identification and engineering decision mapping of the unstable critical state of the goaf: based on the collected mechanical response data, the stress deflection characteristics of the surrounding rock, the evolution law of stress / displacement cloud map and the expansion behavior of the plastic zone are analyzed, and a multi-criteria identification system for the unstable critical state is constructed, including (1) reading the stress tensor data of the monitoring point and the vertical displacement data of the monitoring point. (2) reading the state data of the plastic zone, extracting the spatial distribution characteristics of shear failure and tensile failure units, and calculating the volume and expansion morphology of the plastic zone; (3) executing the instability identification logic: if stress reversal is detected at the dangerous point of the roof, that is, the horizontal stress ( A sudden change occurs exceeding the vertical stress ( Furthermore, if the vertical displacement is greater than 100mm, and the plastic zone of the surrounding rock in the goaf has formed a butterfly-shaped expansion zone and connects with the fault zone, this step sequence is marked as the intervention time for backfilling operations. Through the above identification system, the critical mining step sequence for instability can be accurately located, providing a quantitative basis for the selection of backfilling timing and the design of backfill strength.

[0027] In specific embodiment 1: (1) Overall layout of mining: The mining area is shaped like a "Z". Starting from the left boundary of the mining area, fluidized bed mining is carried out step by step and layer by layer in a "Z" shape. The mining section is a 5m × 5m square, as shown below. Figure 2 , Figure 3 As shown.

[0028] (2) Step-by-step mining design: The mining process is divided into 4 steps: Step 1: Starting from the left boundary, mine along the outermost layer of the Z-shape, with the mining direction to the right. Each mining step is 10 meters long, and the mining is repeated for 40 steps.

[0029] Step 2: Begin to expand forward and mine the second layer in a Z-shape. Each step in this stage is 10 meters long, and the mining proceeds from right to left for 40 steps.

[0030] Step 3: Continue to expand forward and mine the last layer of the Z-shape. Each step in this stage is 10 meters long. Mine from left to right for 40 steps to complete the first Z-shape mining.

[0031] Step 4: Repeat steps 1, 2, and 3. Repeat the zigzag mining process described above until an instability signal in the surrounding rock of the goaf is detected.

[0032] (3) Model construction method: First, Rhino software was used to build an accurate three-dimensional geometric solid model containing coal seams and rock strata of different thicknesses, as well as a normal fault zone with a dip angle of 45°, such as Figure 4 , Figure 5 As shown, a normal fault with a thickness of 5 meters and a dip angle of 45° is set and placed directly above the coal seam. In the model's preset coal seam, a Z-shaped mining area is pre-defined, with 40 pre-defined areas of 5 meters each for the first mining phase. 5 A 10m rectangular solid mining block is embedded sequentially from the left boundary of the stope to the right boundary of the stope; this is the first layer of the Z-shaped mining. The second step of mining will involve 40 pre-set areas of 5m each. 5 A 10m rectangular solid mining block is embedded into a Z-shaped second layer from right to left; the third step of mining will target 40 pre-set areas of 5. 5 A 10m rectangular solid mining block is embedded from left to right into the third layer of the Z-shaped structure. This completes the construction of the first Z-shaped pre-embedded mining block configuration.

[0033] Secondly, the Rhino plugin Griddle is used to efficiently mesh 3D solids, such as... Figure 6 As shown. When meshing the surface, the shortest side length of the mesh is set to 1m and the longest side length to 1.5m. Quadrilaterals are selected as the main type of mesh for meshing. Finally, volume meshing is performed. The mesh generated by Griddle is of high quality and can handle complex interfaces well.

[0034] (4) Numerical simulation implementation method: Physical and mechanical parameters of each coal and rock layer are set as shown in Table 1 and Table 2. Since this simulation is based on the background of deep coal and rock fluidized mining, the mining of Zhangshuanglou Coal Mine is selected as the actual mining background. The length, width and height of the model are 500×500×150.6m, the thickness of the coal seam in the mining area is 5m, the mining depth of the coal seam is selected as 1050m, a high ground stress of 25.5MP is applied to the upper part of the model, the bottom of the model is fixed, the horizontal constraints in the x direction are applied to the left and right, and the horizontal constraints in the y direction are applied to the front and back. The fault zone height is 112.3m, the dip angle is 45°, and it is located directly above the coal seam. The material parameters of each rock layer in the model are calculated based on the existing laboratory measured data.

[0035] Table 1. Physical and mechanical parameters of rock mass

[0036] Table 2 Physical and mechanical parameters of the fault zone

[0037] Secondly, the Mohr-Coulomb constitutive model was selected to monitor the historical stress and displacement of the central point of the surrounding rock roof corresponding to all mining steps.

[0038] Finally, a convergence equilibrium calculation is performed on the unmined model. After the calculation, the initial displacement of each node is set to 0 to eliminate the displacement and settlement caused by the initial model calculation, focusing on the displacement and settlement after mining. The calculation model after each mining step is saved. Through this step-by-step and layered mining process, from short to long, from outside to inside, the progressive failure process of the surrounding rock in the goaf can be monitored most intuitively, thereby accurately locating the instability critical point for subsequent result analysis.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The methods disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be found in the method section.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A visual modeling and analysis method for in-situ fluidized bed mining of coal with fault structures, characterized in that, include: S1, Configure the geometric parameters and topological path of the zigzag progressive fluidized bed mining in the numerical simulation system; S2, acquire borehole data and geological profile of the target mining area, extract coal seam roof and floor elevation data and fault zone geometric feature parameters, and generate a spatial vector dataset describing the geological structure; S3. Based on the spatial vector dataset, construct a geometric entity model of the rock strata and fault zone, map the rock mechanics parameters measured in the laboratory to the corresponding geometric entity, set the contact relationship between the fault zone and the coal and rock strata, and generate a geomechanical prototype containing material properties. S4. Import the geomechanical prototype into the three-dimensional modeling software, use linear array solid cuboid units to generate several independent mining unit entities with equal geometric dimensions to be pre-embedded in the mining area, and number each independent mining unit entity according to the topological path to construct a three-dimensional geological-engineering composite model containing a preset mining sequence. S5. Perform geometric topology repair on the three-dimensional geological-engineering composite model. First, generate a surface mesh dominated by quadrilaterals at the model boundary, and then use a remeshing algorithm to generate an unstructured volume mesh dominated by hexahedrons. S6. Import the unstructured body mesh into the numerical analysis platform, establish mining unit groups and rock strata groups according to the sequence number, and assign corresponding constitutive models and mechanical parameters respectively; apply displacement boundary conditions and overlying rock strata loads, perform initial geostress field equilibrium calculations until the model reaches steady state, and set up stress and displacement monitoring points in the fault zone and surrounding rock of the goaf. S7. Based on the sequence number of the topological path, the constitutive model of the corresponding mining unit group is changed to an empty model step by step to simulate the fluidized mining process. After each step of the mining calculation balance, the monitoring data is recorded and a full-sequence mechanical response database is constructed; S8. Based on the full-sequence mechanical response database, when the current mining sequence is detected to be in an unstable critical state, the sequence is marked as the intervention time for backfilling operation.

2. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 1, characterized in that, S3 specifically includes: using a rock mass quality evaluation system to score the geological strata and fault zones in the mining area to obtain rock mass quality indicators; calculating the strength reduction coefficient based on the rock mass quality indicators; using the strength reduction coefficient to correct the rock mechanics parameters measured in the laboratory to obtain engineering rock mass physical and mechanical parameters; and assigning the engineering rock mass physical and mechanical parameters to the corresponding geometric entity model to complete the parameter mapping from laboratory data to engineering-scale constitutive models.

3. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 1, characterized in that, S4 specifically includes: S4.1, import the geometric data of the geomechanical prototype generated in step S3 into the 3D modeling software, and reconstruct the 3D entities of the coal seam, roof and floor and fault zone according to the coordinate system. S4.2 Based on the preset Z-shaped mining path parameters, several independent mining unit entities with equal geometric dimensions are generated and pre-embedded in the mining area using linear array solid cuboid units, and each independent block is serialized and numbered. S4.3, use NURBS surface tools to repair the geometric gaps caused by cutting, and ensure that the contact surface topology between the fault zone entity and the coal seam entity is consistent; S4.4 combines the processed coal seam mining unit entities, surrounding rock entities, and fault zone entities to generate a three-dimensional geological-engineering composite model that does not contain geometric overlaps or voids.

4. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 1, characterized in that, S5 specifically includes: S5.1, Use the remeshing tool to repair the boundary surfaces of the three-dimensional geological-engineering composite model and remove debris surfaces and overlapping surfaces; S5.2 Generates a surface mesh dominated by quadrilaterals on the model surface and sets the upper and lower limits of the mesh size parameters; S5.3, Based on the surface mesh, the interior of the model is filled using a volume mesh generation algorithm to generate an unstructured volume mesh dominated by hexahedrons; S5.4 performs mesh quality checks, calculates the Jacobian ratio, removes or repairs distorted elements, and finally exports the mesh file in a format compatible with the numerical computing platform.

5. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 4, characterized in that, S6 specifically includes: S6.1 Import the grid file into the numerical analysis platform and divide each independent mining block into an independent mining group according to the serialization number; S6.2, Call the Mohr-Coulomb constitutive model and assign the rock mass physical and mechanical parameters obtained in step S3 to the rock strata group and fault zone group respectively; S6.3, apply the overlying strata load and boundary displacement constraints, run the calculation until the maximum unbalanced force converges, and obtain the initial geostress field; S6.4, clear the model displacement field to zero, and define historical variable monitoring points at preset positions on the slip surface of the fault zone and the roof of the Z-shaped goaf.

6. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 1, characterized in that, S7 specifically includes: constructing a cyclic mining step, and according to the sequence number i of the zigzag path, i=1, 2, 3..., N, executing the following loop in sequence: modifying the constitutive model of the mining unit group numbered i to an empty model, simulating the removal of rock mass; running numerical calculations to the preset equilibrium standard; traversing all monitoring points, extracting and recording the current stress tensor, displacement vector and plastic zone state, and constructing a full-sequence mechanical response database; saving the stress field data file of the current calculation step, until the mining simulation of all preset units is completed.

7. The visualization modeling and analysis method for in-situ fluidized bed mining of coal with fault structures according to claim 1, characterized in that, S8 specifically includes: S8.1, Read the stress tensor data and vertical displacement data of the monitoring point; S8.2, Read the state data of the plastic zone, extract the spatial distribution characteristics of shear failure and tensile failure elements, and calculate the volume and expansion morphology of the plastic zone; S8.3, Execute instability detection logic: If stress reversal (i.e., horizontal stress) is detected at a critical point on the top plate... Sudden change exceeding vertical stress Furthermore, if the vertical displacement is greater than 100mm, and the plastic zone of the surrounding rock in the goaf has formed a butterfly-shaped expansion zone and is connected to the fault zone, the current mining sequence is determined to be in an unstable critical state, and this sequence is marked as the intervention time for backfilling operations.

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