Overburden rock damage field multi-source sensing fusion indoor reconstruction test method
Through the multi-source sensing fusion indoor reconstruction test method of rock-covered damage field, the problems of model deviation, high monitoring cost and difficulty in reproducing topological structures in rock-covered damage research were solved, and the precise simulation and prediction of rock-covered damage field was realized, supporting the safe mining of deep mines.
Patent Information
- Application Number
- CN202510539624.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-08-19
AI Technical Summary
In the research on rock-covered damage, the existing technology has problems such as model prediction and measured data deviation, high on-site monitoring costs and limited information, missing damage quantification benchmarks and difficulty in reproducing three-dimensional discontinuous topological structures, resulting in inaccurate simulation of rock-covered damage field in deep mines.
The multi-source sensing fusion indoor reconstruction test method of rock-covered damage field was adopted. By integrating geological and hydrological, historical mining and future mining planning data, observation drilling was arranged and integrated fiber and DAS monitoring devices were installed to construct an in-situ three-dimensional damage model, and similar material test pieces were prepared using a multi-directional hydraulic servo system, combining acoustic emission and fiber optic monitoring of rock-covered damage evolution.
The precise indoor reconstruction of the overlying rock damage field is realized, and accurate prediction and active prevention and control solutions for the water-conducting crack zone under complex deep conditions are provided, which improves the accuracy and efficiency of overlying rock damage research.
Smart Images
Figure CN120507802A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of mine engineering geological simulation, and in particular to a multi-source sensing fusion indoor reconstruction test method for an overburden damage field. Background Art
[0002] Coal, as the main energy source, faces major technical challenges in its safe mining. Deep mines are affected by the coupling of extremely thick loose layers and high-intensity mining, and overburden damage presents significant three-dimensional discontinuous gradient characteristics. The existing overburden damage research technology system has three key defects: First, the traditional key layer theory is constructed based on the assumption of rock integrity and does not consider the spatial gradient distribution characteristics of the mining damage field, resulting in significant deviations between model predictions and measured data; second, field monitoring technology has limitations. Single-hole peek technology is expensive for single-point detection and can only obtain local two-dimensional information. Although microseismic, InSAR and other technologies can achieve large-scale monitoring, their spatial resolution and temporal resolution make it difficult to capture the dynamic evolution of damage at the millimeter / second level; finally, the current physical simulation method uses a homogeneous model and rigid loading mode, which has problems such as the lack of damage quantification benchmark and difficulty in reproducing three-dimensional discontinuous topological structures. The similarity between the experimental model and the field damage field is insufficient.
[0003] Therefore, in order to solve this problem, we proposed a multi-source sensing fusion indoor reconstruction test method for overburden damage field. Summary of the Invention
[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a multi-source sensing fusion indoor reconstruction test method for overburden damage field.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] A multi-source sensing fusion indoor reconstruction test method for overburden damage field includes the following steps:
[0007] Step 1: Basic data collection, integrating geological and hydrological data, historical mining data and future mining plans of the study area;
[0008] Step 2: Establish an observation system. Observation boreholes are laid out in the overburden of the study area, and monitoring devices integrating optical fiber and DAS are installed. A parallel electrical observation system is also deployed simultaneously.
[0009] Step 3: In-situ 3D damage field construction, integrating resistivity, DAS and strain data, establishing a damage quantification model through data fusion inversion, and generating an in-situ 3D damage model;
[0010] Step 4: Preparation of in-situ damage field specimens: Determine the test device dimensions based on similarity criteria, construct a similar material simulation test device, associate damage parameters through spatial coordinates, and use a multi-directional hydraulic servo system to accurately prefabricate standardized specimens with dual-control geometry and damage characteristics;
[0011] Step 5: Reconstruct the in-situ damage field indoors. Roughen the interface of the prefabricated specimens and bond them with low-viscosity epoxy resin. Apply axial preload in a similar material simulation test device to simulate overburden. Build an overburden monitoring system integrating acoustic emission, optical fiber, and a total station to observe damage evolution and rock migration patterns after simulated excavation.
[0012] Preferably, in step 1, the historical damage records of the overburden in the study area are summarized by analyzing historical mining data to provide a dynamic evolution basis for the three-dimensional damage field model. By analyzing future mining plans, the layout density of observation boreholes is optimized to ensure that the constructed three-dimensional damage field model is consistent with the actual mining sequence during subsequent simulations.
[0013] Preferably, in step 2, the parallel electrical method 64-pole array uses resistivity anomalies to identify data on fracture development zones in the overburden in the monitoring study area, and the distributed optical fiber uses Brillouin frequency shift demodulation to obtain data on the strain evolution process of the overburden in the monitoring study area. The two types of data are mapped to a three-dimensional grid unit with a side length of 50 cm through a unified coordinate system, and the damage quantification model function is constructed as follows:
[0014]
[0015] In the above formula, α and β are weighted coefficients determined according to the lithologic anisotropy index, α+β=1; Δρ and ρ0 are the difference and initial value of the parallel electrical method observation, ε and ε are respectively max are the observed value of optical fiber observation and the observed ultimate strain, respectively.
[0016] Preferably, based on the damage quantification model function, the overburden damage field is converted into a continuous field variable through a three-dimensional interpolation method, and the dimensional difference between the crack development zone data and the strain evolution process data is eliminated by range normalization to form a structured input data field and obtain the interpolation parameters.
[0017] Preferably, an adaptive adjustment mechanism of the damage quantification model function is introduced in step 2. According to the spatial correlation of resistivity, DAS data and strain data, the interpolation parameters are dynamically optimized, and the damage degree of each three-dimensional grid unit is output as D∈[0,1], where D>0.6 is defined as a high damage zone, 0.3≤D≤0.6 is a transition zone, and D<0.3 is a stable zone.
[0018] Preferably, in step 3, a coordinate system is established based on a similar material simulation experimental device, and the size, position, and damage degree of each grid are determined according to the similarity principle, which is expressed as f(x, y, D).
[0019] Preferably, in step 3, in order to further achieve the quantitative transformation from the in-situ three-dimensional damage field model to the mechanical properties of the physical specimen, a matching function is established as follows:
[0020] f(D)=aD b +c
[0021] In the above formula, a, b, and c are lithology-related parameters calibrated through orthogonal experiments. The damage degree D has a nonlinear relationship with material strength and brittleness. During the layered design, the original spatial topological structure of the high-damage area (D>0.6) is retained to avoid the distortion of damage morphology caused by traditional homogeneous materials.
[0022] Preferably, the multi-directional hydraulic servo system in step 4 includes a vertical hydraulic cylinder and a lateral hydraulic cylinder. The vertical hydraulic cylinder and the lateral hydraulic cylinder apply a gradient stress field to the specimen, which can avoid the damage concentration phenomenon caused by one-time loading. The vertical hydraulic cylinder applies stress σ when loading vertically downward. v , the horizontal stress is maintained at σ by the lateral hydraulic cylinder h , simulating the in-situ stress state, the calculation formulas of the two stresses are as follows:
[0023] σ v =γH
[0024] σ h =kσ v
[0025] Where γ represents the average bulk density of the rock layer, H is the burial depth, and k is the coefficient term, with a value between 0.5 and 1.2.
[0026] Preferably, in step 5, the joint surface of the prefabricated specimen is sandblasted to form a rough interface, and a low-viscosity epoxy resin is used to infiltrate the rough interface between the two prefabricated specimens. The adhesive is injected along the joint of the prefabricated specimens through a micro-syringe at a rate of 0.2 mL / s and cured in a constant temperature box at 60°C for 2 hours. Subsequently, a vertical downward preload of 0.1 MPa is applied by a hydraulic jack to perform an axial preload operation to eliminate the gap in the joint of the prefabricated specimens.
[0027] Preferably, in step 5, an acoustic emission sensor device is arranged on one side of the similar material simulation test device, with a distributed optical fiber embedded inside, and a total station is set up on one side of the similar material simulation test device, and data acquisition timing alignment is achieved through a time code synchronizer. By installing a retractable metal bar or plastic plate on the working face, the metal bar or plastic plate is uniformly pulled out by an electric telescopic rod to simulate mining, and the mining simulation working face is advanced at a rate of 0.5 m / h according to the mining plan, and the number of acoustic emission events, the sudden change in optical fiber strain and the amount of roof subsidence are synchronously collected. The Geiger algorithm is used to locate the acoustic emission events, and the optical fiber strain data and the displacement data recorded by the total station are fused through Kalman filtering. The spatiotemporal evolution of microfractures is captured by acoustic emission, the optical fiber monitors the continuous strain field, and the total station records the degree of damage development of the overburden and the migration law of the simulated overburden.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] The present invention can effectively solve the technical difficulties of indoor reconstruction of the overburden damage field. By carrying out distributed optical fiber monitoring, DAS microseismic monitoring, and parallel electrical observation, resistivity, DAS data, and strain data are collected. Through data preprocessing, data fusion and inversion, and damage field quantification, the in-situ three-dimensional damage field of the overburden in the study area is characterized. Then, three-dimensional damage field specimens of the overburden in the study area are prepared, and a similar material simulation test device is built to realize indoor reconstruction of the in-situ three-dimensional damage field of the overburden. This method not only provides a solution for the accurate prediction and active prevention and control of water-conducting fracture zones under deep and complex conditions, but also lays the foundation for research and application in related fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0031] Figure 1 For the technology roadmap;
[0032] Figure 2 This is a gridded schematic diagram of the overburden damage field in the study area;
[0033] Figure 3 This is a schematic diagram of the layout of the overburden observation boreholes in the study area;
[0034] Figure 4 This is a schematic diagram of the vertical observation borehole structure;
[0035] Figure 5 Schematic diagram of prefabrication of test specimens;
[0036] Figure 6 Schematic diagram of the simulation test device for similar materials.
[0037] In the figure: 1. Working face to be mined; 2. Parallel electrical sensing device; 3. Goaf; 4. Fiber-optic DAS monitoring hole; 5. Metal-based rope-like optical fiber; 6. Internal fixed-point sensing optical fiber; 7. DAS sensing optical fiber; 8. Counterweight guide; 9. Stress control device; 10. Transmission line; 11. Pressurization device housing; 12. Base; 13. Vertical bottom fixed pressurization device; 14. Test piece; 15. Horizontal fixed pressurization device; 16. Top dynamic pressurization device; 17. Indoor simulation device housing; 18. Tightly wrapped sensing optical fiber; 19. Total station monitoring calibration point; 20. Acoustic emission sensing device; 21. Total station. DETAILED DESCRIPTION
[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0039] Reference Figures 1 to 6 , a multi-source sensing fusion indoor reconstruction test method for overburden damage field, Figure 1 For the technology roadmap. Figure 2 Figure 1 is a gridded schematic diagram of the overburden damage field in the study area, where a, b, and h are the abstract length, width, and height of the overburden, respectively (xn, yn, zn, Dn). That is, a, b, and h are the length, width, and height of the overburden, respectively, and the coordinates of the nth grid are (xn, yn, zn), and its damage degree is Dn. Figure 3 This is a schematic diagram of the layout of overburden observation boreholes in the study area, including: working face to be mined 1, parallel electrical sensing device 2, goaf 3, and fiber-optic DAS monitoring hole 4. Figure 4 Schematic diagram of vertical observation borehole structure, which includes metal-based cable-like optical fiber 5, internal fixed-point sensing optical fiber 6, DAS sensing optical fiber 7, and counterweight guide head 8. Figure 5 Schematic diagram of test specimen prefabrication, including stress control device 9, transmission line 10, pressurizing device housing 11, base 12, vertical bottom fixed pressurizing device 13, test specimen 14, horizontal fixed pressurizing device 15, and top dynamic pressurizing device 16. Figure 6 Schematic diagram of a similar material simulation test device, which includes: an indoor simulation device shell 17, a tightly wrapped sensing optical fiber 18, a total station monitoring calibration point 19, an acoustic emission sensor device 20, and a total station 21.
[0040] Step 1: Collect basic data, integrate geological and hydrological data of the study area (including stratigraphic structure, lithologic distribution, hydrogeological parameters and structural characteristics), historical mining data (goaf area range, mining depth, roof collapse characteristics) and future mining planning (working face layout, advancement speed, mining height design), that is, collect geological histograms, rock mass mechanical parameters (compressive strength, elastic modulus, Poisson's ratio), hydrogeological data (permeability coefficient, aquifer thickness) of the study area, analyze the distribution law of key overburden layers and potential damage evolution path of the study area, identify key monitoring areas, and collect geological, hydrological and mining data. Figure 3 For example, the overburden in the study area includes the mining face 1 and goaf 3. The strike and dip length of mining face 1 are Z1 and Q1, respectively, while the strike and dip length of the goaf are Z2 and Q2, respectively. Both mining depths are S, and the mining method is caving. Key monitoring areas are defined as the surface areas corresponding to mining face 1 and goaf 3, as well as the coal pillar between them.
[0041] Step 2: Establish an observation system, including distributed optical fiber monitoring, DAS microseismic monitoring, and parallel electrical observation. The specific steps are to determine the number, location, and aperture of observation boreholes based on the collected geological, hydrological, and mining data, and to arrange observation boreholes on the overburden in the study area. The observation boreholes include vertical observation boreholes and horizontal observation boreholes. Distributed optical fibers (BOTDA technology, spatial resolution 0.5m) are arranged in the vertical boreholes at a spacing of 10m. Figure 3 The fiber-optic DAS monitoring hole 4 is shown in the figure. A 64-electrode array (electrode spacing 1m) is arranged in parallel in the horizontal borehole. One is arranged near the opening hole and the stop line of the working face 1 and the goaf 3 to be mined, and a vertical observation borehole is arranged above the coal pillar between the two. The internal structure of the vertical observation borehole is shown in the figure. Figure 4 As shown, the aperture is 130cm. A distributed fiber optic cable is laid out at 10m intervals in the vertical observation borehole. The distributed fiber optic cable includes an internal fixed-point sensing fiber 6, a distributed fiber optic monitoring loop, and a DAS sensing fiber 7. The distributed fiber optic monitoring loop is a metal-based cable-like fiber 5, which is lowered to the bottom of the vertical borehole through a counterweighted guide 8. The internal fixed-point sensing fiber 6 is connected to a distributed fiber optic interrogator, and the DAS sensing fiber 7 is connected to a DAS interrogator. A parallel electrical 64-electrode array (electrode spacing 1m) is laid out in the horizontal observation borehole, covering the planned working face 1 and the corresponding ground portion of the goaf 3, as shown in the figure. Figure 3 Parallel electrical sensing device 2. Data monitoring is performed before mining at the planned working face. Distributed optical fiber uses Brillouin frequency shift to invert the strain field, specifically Brillouin optical time-domain reflectometry. DAS sensing fiber uses acoustic detection to monitor the evolution of overburden damage. Parallel electrical sensing uses resistivity anomalies to identify fracture development areas. Resistivity, DAS, and strain data are collected simultaneously.
[0042] Step 3: Construct an in-situ three-dimensional damage field, including data preprocessing, data fusion and inversion, and quantitative characterization of the damage field. The specific steps are to simultaneously collect resistivity, DAS data, and strain data, preprocess, fuse, and invert the collected resistivity, DAS, and strain data, and map the collected resistivity, DAS, and strain data to a three-dimensional grid unit with a side length of 50 cm through a unified coordinate system. Then, a damage quantification model is constructed to achieve quantitative characterization of the in-situ three-dimensional damage field. The in-situ three-dimensional damage field model is obtained, and the resistivity, DAS, and strain data are converted into continuous field variables to provide structured input for subsequent interpolation parameters. At the same time, dimensional differences are eliminated through normalization to construct a damage quantification model.
[0043] Based on the in-situ 3D damage field model, the scale of the similar material simulation test device was determined according to similarity criteria (geometric ratio 1:200, density ratio 1:1.6, and strength ratio 1:100). The same formation was divided into grids of a certain size according to thickness. The coordinate properties of the similar material simulation test device were then used to determine the grid position and damage extent.
[0044] In step 1, historical mining data are analyzed to summarize the historical damage records of the overburden in the study area, providing a dynamic evolution basis for the three-dimensional damage field model. By analyzing future mining plans, the layout density of observation boreholes is optimized to ensure that the constructed three-dimensional damage field model is consistent with the actual mining sequence during subsequent simulations.
[0045] In step 2, the parallel electrical method 64-pole array uses resistivity anomalies to identify data on fracture development areas in the overburden in the monitoring study area. The distributed optical fiber uses Brillouin frequency shift demodulation to obtain data on the strain evolution process of the overburden in the monitoring study area. The two types of data are mapped to a 50 cm side length three-dimensional grid unit using a unified coordinate system. The damage quantification model function is constructed as follows:
[0046]
[0047] In the above formula, α and β are weighted coefficients determined according to the lithologic anisotropy index, α+β=1; Δρ and ρ0 are the difference and initial value of the parallel electrical method observation, ε and ε are respectively max are the observed value of optical fiber observation and the observed ultimate strain, respectively.
[0048] At the same time, an adaptive adjustment mechanism of the damage quantification model function is introduced in step 2. According to the spatial correlation of resistivity, DAS data and strain data, the interpolation parameters are dynamically optimized, and the damage degree of each 3D grid cell is output as D∈[0,1], where D>0.6 is defined as a high damage zone, 0.3≤D≤0.6 is a transition zone, and D<0.3 is a stable zone.
[0049] The final result is Figure 2 , get the damage of all grids, where the coordinates of the nth grid are (x n ,y n ,z n ), the damage degree is D n .
[0050] Step 4, preparation of in-situ damage field specimens, including size determination, material configuration, and preparation of damage specimens. The specific steps are to determine the geometric scale of the similar material simulation test device based on the in-situ three-dimensional damage field model according to the similarity principle, construct a similar material simulation test device containing a rigid frame structure, and grid the target stratum in the thickness direction. The coordinate system established by the similar material simulation test device is used to spatially locate each layer of grids and associate the damage parameters of the corresponding area to obtain a gridded specimen; a multi-directional hydraulic servo system is used to pre-damage the gridded specimen, and the multi-axis coordinated control of the multi-directional hydraulic servo system is used to achieve accurate reproduction of the preset damage degree and geometric dimensions to obtain a prefabricated specimen. In step 3, a coordinate system is established based on the similar material simulation test device, and the size, position, and damage degree of each grid are determined according to the similarity principle, expressed as f(x, y, D). At the same time, in order to achieve quantitative conversion from the in-situ three-dimensional damage field model to the mechanical properties of the physical specimen, a matching function is established as follows:
[0051] f(D)=aD b +c
[0052] In the above formula, a, b, and c are lithology-related parameters calibrated through orthogonal experiments. The damage degree D has a nonlinear relationship with material strength and brittleness. During the layered design, the original spatial topological structure of the high-damage area (D>0.6) is retained to avoid the distortion of damage morphology caused by traditional homogeneous materials.
[0053] Specific examples Figure 5 As shown, a specimen 14 is placed in a pressurizing device housing 11 and subsequently secured to a base 12. The size, position, and damage level of each grid cell are input into a stress control device 9. Transmission lines 10 control the vertical bottom fixed pressurizing device 13, the horizontal fixed pressurizing device 15, and the top dynamic pressurizing device 16, applying varying degrees of stress to the specimen 14 to create an in-situ damage field specimen. The vertical bottom fixed pressurizing device 13, the horizontal fixed pressurizing device 15, and the top dynamic pressurizing device 16 constitute a multi-directional hydraulic servo system.
[0054] Step 5: Indoor reconstruction of the in-situ damage field, including specimen interface treatment, specimen installation and monitoring, and model excavation. The specific steps are to perform interface roughening treatment on the prefabricated specimens, configure multiple prefabricated specimens with low-viscosity epoxy resin penetrating adhesive, inject low-viscosity epoxy resin penetrating adhesive along the joint line of two prefabricated specimens with a syringe, install the combined multiple prefabricated specimens in the rigid frame structure of the similar material simulation test device, and then apply axial preloading from top to bottom to finally obtain the simulated overburden of the similar material simulation test device; construct a simulated overburden displacement monitoring system for the similar material simulation test device based on the acoustic emission device, distributed optical fiber, and total station 21, as shown in FIG. Figure 6 As shown, the acoustic emission device is an acoustic emission sensor device 20; a simulated excavation operation is performed according to the designed working face to observe the damage development degree of the overburden and simulate the migration law of the overburden.
[0055] The multi-directional hydraulic servo system in step 4 includes a vertical hydraulic cylinder and a lateral hydraulic cylinder. The vertical hydraulic cylinder and the lateral hydraulic cylinder apply a gradient stress field to the specimen to avoid the damage concentration phenomenon caused by one-time loading. The vertical hydraulic cylinder applies stress σ when loading vertically downward. v , the horizontal stress is maintained at σ by the lateral hydraulic cylinder h , simulating the in-situ stress state, the calculation formulas of the two stresses are as follows:
[0056] σ v =γH
[0057] σ h =kσ v
[0058] Where γ represents the average bulk density of the rock layer, H is the burial depth, and k is the coefficient term, with a value between 0.5 and 1.2.
[0059] In step 5, the joint surfaces of the prefabricated specimens were sandblasted with a particle size of 0.3-0.5 mm and an air pressure of 0.6 MPa. This created a rough interface with an Ra of 50-80 μm. A low-viscosity epoxy resin infiltration adhesive was then injected along the joint surface of the two prefabricated specimens via a microsyringe at a rate of 0.2 mL / s. The adhesive was cured in a 60°C thermostat for 2 hours. Subsequently, a hydraulic jack applied a vertical downward preload of 0.1 MPa to eliminate gaps in the joints. The low-viscosity epoxy resin infiltration adhesive had an η of 120 mPa·s.
[0060] In step 5, an acoustic emission sensor device is arranged on one side of the similar material simulation test device, and a distributed optical fiber is embedded inside, such as Figure 6As shown, the similar material simulation test device is an indoor simulation device housing 17, and the distributed optical fiber is a tightly wrapped sensing fiber 18. A total station 21 is installed on one side of the similar material simulation test device, and several total station monitoring calibration points 19 are arranged in a side array. Data acquisition timing is aligned (error <1ms) using a time code synchronizer. Retractable metal bars or plastic plates are installed on the working face, and the metal bars or plastic plates are uniformly withdrawn using an electric telescopic rod to simulate mining. The simulated mining working face is advanced at a rate of 0.5m / h according to the mining plan, i.e., simulated mining is carried out, and portions of the model coal seam are gradually hollowed out. The number of acoustic emission events, sudden changes in optical fiber strain, and roof subsidence are simultaneously collected. The Geiger algorithm is used to locate acoustic emission events. The optical fiber strain data is fused with the displacement data recorded by the total station 21 through a Kalman filter. The spatiotemporal evolution of microfractures is captured through acoustic emission. The optical fiber monitors the continuous strain field. The total station 21 records the degree of damage development in the overburden and the migration patterns of the simulated overburden, namely, the development of water-conducting fracture zones and the macroscopic displacement of the simulated overburden.
[0061] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.
Claims
1. A multi-source sensing fusion indoor reconstruction test method for overburden damage field, characterized in that: The steps include: Step 1: Basic data collection, integrating geological and hydrological data, historical mining data and future mining plans of the study area; Step 2: Establish an observation system. Observation boreholes are laid out in the overburden of the study area, and monitoring devices integrating optical fiber and DAS are installed. A parallel electrical observation system is also deployed simultaneously. Step 3: In-situ 3D damage field construction, integrating resistivity, DAS and strain data, establishing a damage quantification model through data fusion inversion, and generating an in-situ 3D damage model; Step 4: Preparation of in-situ damage field specimens: Determine the test device dimensions based on similarity criteria, construct a similar material simulation test device, associate damage parameters through spatial coordinates, and use a multi-directional hydraulic servo system to accurately prefabricate standardized specimens with dual-control geometry and damage characteristics; Step 5: Reconstruct the in-situ damage field indoors. Roughen the interface of the prefabricated specimens and bond them with low-viscosity epoxy resin. Apply axial preload in a similar material simulation test device to simulate overburden. Build an overburden monitoring system integrating acoustic emission, optical fiber, and a total station to observe damage evolution and rock migration patterns after simulated excavation.
2. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 1 is characterized in that: In step 1, the historical damage records of the overburden in the study area are summarized by analyzing historical mining data to provide a dynamic evolution basis for the three-dimensional damage field model. By analyzing future mining plans, the layout density of observation boreholes is optimized to ensure that the constructed three-dimensional damage field model is consistent with the actual mining sequence during subsequent simulations.
3. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 1 is characterized in that: In step 2, the parallel electrical method 64-pole array uses resistivity anomalies to identify data on fracture development areas in the overburden in the monitoring study area. The distributed optical fiber uses Brillouin frequency shift demodulation to obtain data on the strain evolution process of the overburden in the monitoring study area. The two types of data are mapped to a 50-cm-long three-dimensional grid unit using a unified coordinate system. The damage quantification model function is constructed as follows: In the above formula, α and β are weighted coefficients determined according to the lithologic anisotropy index, α+β=1; Δρ and ρ0 are the difference and initial value of the parallel electrical observation respectively, ε and ε max are the observed value of optical fiber observation and the observed ultimate strain, respectively.
4. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 3 is characterized in that: Based on the damage quantification model function, the overburden damage field is converted into a continuous field variable through a three-dimensional interpolation method. The dimensional difference between the data of the fracture development zone and the strain evolution process data is eliminated by range normalization to form a structured input data field and obtain the interpolation parameters.
5. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 4 is characterized in that: In step 2, an adaptive adjustment mechanism of the damage quantification model function is introduced. According to the spatial correlation of resistivity, DAS data, and strain data, the interpolation parameters are dynamically optimized, and the damage degree of each three-dimensional grid cell is output as D∈[0,1], where D>0.6 is defined as a high damage zone, 0.3≤D≤0.6 is a transition zone, and D<0.3 is a stable zone.
6. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 1 is characterized in that: In step 3, a coordinate system is established based on the similar material simulation experimental device, and the size, position, and damage degree of each grid are determined according to the similarity principle, which is expressed as f(x, y, D).
7. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 6 is characterized in that: In step 3, in order to further achieve the quantitative transformation from the in-situ three-dimensional damage field model to the mechanical properties of the physical specimen, the matching function is established as follows: f(D)=aD b +c In the above formula, a, b, and c are lithology-related parameters calibrated through orthogonal experiments. The damage degree D has a nonlinear relationship with material strength and brittleness. During the layered design, the original spatial topological structure of the high-damage area (D>0.6) is retained to avoid the distortion of damage morphology caused by traditional homogeneous materials.
8. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 1 is characterized in that: The multi-directional hydraulic servo system in step 4 includes a vertical hydraulic cylinder and a lateral hydraulic cylinder. The vertical hydraulic cylinder and the lateral hydraulic cylinder apply a gradient stress field to the specimen to avoid the damage concentration phenomenon caused by one-time loading. The vertical hydraulic cylinder applies stress σ when loading vertically downward. v , the horizontal stress is maintained at σ by the lateral hydraulic cylinder h , simulating the in-situ stress state, the calculation formulas of the two stresses are as follows: s v =γH s h =kσ v Where γ represents the average bulk density of the rock layer, H is the burial depth, and k is the coefficient term, with a value between 0.5 and 1.
2.
9. The method for indoor reconstruction of a rock damage field by multi-source sensing fusion according to claim 1 is characterized in that: In step 5, the joint surface of the prefabricated specimens was sandblasted to form a rough interface. A low-viscosity epoxy resin infiltration adhesive was used between the rough interfaces of the two prefabricated specimens. The adhesive was injected along the joint of the prefabricated specimens through a micro-syringe at a rate of 0.2 mL / s and cured in a constant temperature box at 60 °C for 2 hours. Subsequently, a vertical downward preload of 0.1 MPa was applied by a hydraulic jack to perform an axial preload operation to eliminate the gap in the joint of the prefabricated specimens.
10. The method for indoor reconstruction of a rock damage field using multi-source sensing fusion according to claim 1 is characterized by: In step 5, an acoustic emission sensor device is arranged on one side of the similar material simulation test device, with a distributed optical fiber embedded inside. A total station is set up on one side of the similar material simulation test device, and data acquisition timing alignment is achieved through a time code synchronizer. By installing a retractable metal bar or plastic plate on the working face, the metal bar or plastic plate is uniformly pulled out by an electric telescopic rod to simulate mining. The mining simulation working face is advanced at a rate of 0.5 m / h according to the mining plan, and the number of acoustic emission events, optical fiber strain mutation and roof subsidence are synchronously collected. The Geiger algorithm is used to locate the acoustic emission events. The optical fiber strain data and the displacement data recorded by the total station are fused through Kalman filtering. The spatiotemporal evolution of microfractures is captured by acoustic emission, the optical fiber monitors the continuous strain field, and the total station records the damage development degree of the overburden and simulates the migration law of the overburden.