A coal mine goaf filling method and system based on simulation technology

Abstract

The application discloses a kind of coal mine goaf filling method and system based on simulation technology, belong to goaf simulation backfill technical field, specifically include: the three-dimensional geological model of target area is constructed, and grouting hole layout optimization model is established and is solved to obtain target grid;Fluid-structure interaction model is established on target grid, the density and viscosity parameters of grouting slurry are obtained and input into the fluid-structure interaction model for simulation, the first Vi that satisfies all lower rock layer different regions dynamic pressure peak value is less than or equal to the preset maximum dynamic pressure threshold is demarcated as initial grouting flow rate V1;Interval obtain the grouting filling thickness of target area, and based on grouting filling thickness H, the corrected grouting flow rate V' is calculated, the grouting flow rate of current grouting device is adjusted to V', the application solves the early slurry waste and later filling deficiency problem caused by traditional fixed flow rate grouting, realizes the efficient use of slurry in filling process.

Description

Technical Field

[0001] This invention relates to the field of simulated backfilling technology for goaf areas, specifically to a method and system for filling goaf areas in coal mines based on simulation technology. Background Technology

[0002] Backfilling of coal mine goafs is a key technology for preventing surface subsidence and ensuring safe production in mining areas. Traditional backfilling methods often employ a fixed-rate grouting process, where the conveying device injects grout at a constant flow rate.

[0003] Traditional grouting construction generally adopts a fixed flow rate injection mode, which fails to fully consider the time-dependent sedimentation characteristics of cement grout and the dynamic changes during the injection process. During the hydration reaction of cement grout, cement particles gradually form a gel structure and undergo volume shrinkage, causing the grout fluidity to decrease exponentially over time. At the same time, unhydrated particles settle and stratify due to density differences, resulting in a non-linear increasing trend in grout density and viscosity. In the initial stage of injection, the grout is in a highly fluid state. If a fixed flow rate is maintained, excess grout is easily lost rapidly in strata with high permeability (such as gravel layers), forming ineffective diffusion channels. As time goes on, the grout gradually loses its fluidity and forms a dense sediment layer. If injection is still carried out at the initial flow rate at this point, the actual filling efficiency will be significantly reduced due to increased grout viscosity and increased pipeline resistance. This is especially problematic in low-permeability strata (such as clay layers), where defects such as grout stagnation in the pipeline, discontinuous filling, or residual pores are likely to occur.

[0004] In addition, traditional processes lack real-time monitoring of grout sedimentation coefficient, porosity changes and formation grout absorption rate, and cannot dynamically adjust flow rate parameters according to the evolution of grout state. This ultimately leads to a dual problem of early grout waste and environmental pollution, and insufficient filling density in the later stage, which seriously affects the grouting reinforcement effect and engineering durability. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for filling coal mine goaf based on simulation technology, and to solve the following technical problems:

[0006] Traditional grouting construction, due to its fixed flow rate mode and lack of real-time monitoring, fails to dynamically adapt to changes in the time-dependent sedimentation of cement grout and the permeability characteristics of the formation, resulting in the dual defects of ineffective diffusion and pollution of grout in the early stage and insufficient compaction of filling in the later stage.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for filling coal mine goaf based on simulation technology includes the following steps:

[0009] S1. Construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into surface meshes. Determine whether the surface mesh is a candidate mesh based on the rock strata engineering parameters. Establish an optimization model for the grouting hole layout based on the candidate mesh and solve it to obtain the target mesh. The rock strata engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata.

[0010] S2, Predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as the fluid-structure interaction boundary to the three-dimensional geological model to construct the fluid-structure interaction model;

[0011] S3, input the density and viscosity parameters of the grout and the engineering parameters of the lower rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0 and simulate the fluid-structure interaction model, obtain the flow velocity field and pressure field at the simulated grouting hole outlet, and transmit the fluid pressure to different areas of the lower rock layer in the target area through the fluid-structure interaction interface;

[0012] S4, obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, then generate a simulation flow rate sequence by gradually decreasing the initial simulated grouting flow rate V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow rate V1.

[0013] S4. The grouting filling thickness of the target area is obtained at intervals, and the corrected grouting flow rate V' is calculated based on the grouting filling thickness H. The grouting flow rate of the current grouting device is adjusted to V'.

[0014] As a further aspect of the present invention: in S1, the specific process for determining the candidate mesh is as follows:

[0015] The rock strata engineering parameters of each surface grid are normalized, and the normalized rock strata parameters are weighted and summed to obtain the candidate score of each surface grid. If the candidate score of any surface grid is greater than or equal to a preset threshold, then the surface grid is marked as a candidate grid.

[0016] As a further aspect of the present invention: in S1, the process of determining the target mesh is as follows:

[0017] With the objective functions of minimizing the total borehole length and maximizing the risk area coverage, real-number encoding is used to generate an initial gene population from the three-dimensional coordinates and borehole status of the candidate grid. The borehole space is optimized by randomly selecting parent individuals to perform continuous gene fragment exchange and recombination. Random offsets are applied to the coordinates of non-critical boreholes with a preset low probability. After each generation iteration, an elite retention mechanism is activated to eliminate the worst individuals. The surface grid corresponding to the globally optimal fitness individual is extracted as the target grid.

[0018] As a further aspect of the present invention: in step S5, the specific process for obtaining the filling thickness is as follows:

[0019] Within a preset monitoring period, the relative permittivity of the grout in the filling area is acquired and input into a preset relative permittivity-sedimentation coefficient curve to obtain the sedimentation coefficient of the grout in the filling area. Based on the sedimentation coefficient, the amount of grout in the monitoring period is corrected to obtain the corrected grout amount. The cross-sectional area of ​​the grouting area is determined based on a three-dimensional geological model. The corrected grout amount and the cross-sectional area of ​​the grouting area are coupled and calculated to obtain the grouting filling thickness H.

[0020] As a further aspect of the present invention, the specific process for constructing the relative permittivity-precipitation coefficient curve is as follows:

[0021] S11. Uniquely number multiple standard samples of grouting slurry and record the corresponding sedimentation state parameters;

[0022] S12, by controlling the dehydration environment parameters, grout samples with different sedimentation states were prepared, and the sample volume shrinkage rate was obtained and a gradient distribution was formed;

[0023] S13, use a vector network analyzer to measure the relative permittivity of each sample within a preset frequency band, and obtain the measured permittivity value corresponding to the sample number;

[0024] S14, pair the volume shrinkage rate of each sample with the corresponding relative permittivity value to generate a discrete data point set, and establish a relative permittivity value-precipitation coefficient curve based on the set using a curve fitting algorithm.

[0025] As a further aspect of the present invention, the specific process for correcting the grout volume is as follows:

[0026] The grouting orifice diameter S of the output device is obtained in advance. The theoretical output grout volume is calculated according to the calculation formula E=V1*T*S. The sedimentation coefficient J corresponding to the grout in the filling area is obtained. The sedimentation coefficient is multiplied by the theoretical output grout volume to obtain the corrected grout volume.

[0027] As a further aspect of the present invention: S5 further includes calculating the actual grouting flow rate V” based on the corrected grout volume E’. If the actual grouting flow rate V” is less than the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V”; if the actual grouting flow rate V” is greater than or equal to the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V’.

[0028] As a further aspect of the present invention: S5 further includes obtaining the grouting flow rate range [N, M] of the current grouting device; if there is a current corrected grouting flow rate V' greater than M, then the grouting flow rate of the current grouting device is adjusted to M; if the grouting filling thickness H is greater than or equal to a preset thickness threshold, then the grouting flow rate of the current grouting device is not adjusted, and the grouting flow rate of the current grouting device is adjusted to N.

[0029] The present invention also includes a coal mine goaf filling system based on simulation technology, used to implement the above-described coal mine goaf filling method based on simulation technology, comprising:

[0030] The target acquisition module is used to construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into a surface mesh. Based on the rock engineering parameters of the surface mesh, it determines whether it is a candidate mesh. Based on the candidate mesh, it establishes an optimization model for the layout of grouting holes and solves it to obtain the target mesh. The rock engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata.

[0031] The model building module is used to predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as fluid-structure interaction boundaries to the three-dimensional geological model to build a fluid-structure interaction model.

[0032] The simulation calculation module is used to input the density and viscosity parameters of the grout and the engineering parameters of the underlying rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0, and simulate the fluid-structure interaction model to obtain the flow velocity field and pressure field at the outlet of the simulated grouting hole, and transmit the fluid pressure to different areas of the underlying rock layer in the target area through the fluid-structure interaction interface.

[0033] The flow velocity determination module is used to obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, the simulated flow velocity sequence is generated by gradually decreasing from the initial simulated grouting flow velocity V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow velocity V1.

[0034] The flow rate correction module is used to obtain the grouting filling thickness of the target area at intervals, and calculate the corrected grouting flow rate V' based on the grouting filling thickness H, so as to adjust the grouting flow rate of the current grouting device to V'.

[0035] The beneficial effects of this invention are:

[0036] 1) This invention, by constructing a three-dimensional geological model and optimizing the grouting hole layout based on rock strata parameters, can accurately identify strata regions with different permeability characteristics. In high-permeability strata, by dynamically comparing the "actual injection capacity" (the ratio of corrected injection volume to cross-sectional area) with the "theoretical flow trend," to avoid grout loss in high-permeability channels due to increased flow velocity with increasing filling height, an artificially decelerated method is adopted to break the theoretical trend of increased flow velocity with increasing filling height, keeping the grout in a low-speed deposition state. In low-permeability strata, the theoretical flow velocity is used as the upper limit to constrain the actual injection rate, avoiding formation damage caused by excessive pressure. This achieves coordinated adaptation between hole layout and flow velocity control, improving the targeting of filling processes under different geological conditions from the source.

[0037] 2) When determining the initial flow rate using a fluid-structure interaction model and genetic algorithm, a dynamic mapping relationship between grouting parameters and formation characteristics is simultaneously established. For high-permeability formations, the total injection volume is reduced by modifying the grouting volume formula, making the actual flow rate significantly lower than the theoretical flow rate, forming a "low-speed sediment retention" grouting mode to suppress the rapid loss of grout in high-permeability channels. For low-permeability formations, when the actual injection capacity exceeds the upper limit of the theoretical flow rate, the theoretical flow rate is automatically used as the execution standard to avoid grout retention or increased pipeline resistance due to excessive flow rate. From the initial filling stage, adaptive matching between flow rate and formation permeability characteristics is achieved, balancing construction efficiency and material retention rate.

[0038] 3) By establishing a closed-loop control mechanism through real-time monitoring of the slurry dielectric constant, the filling requirements of different formations can be dynamically responded to. In the early stage of filling high-permeability formations, the flow rate control dominated by the actual injection capacity is used to suppress slurry loss. Combined with the filling thickness calculated by the three-dimensional geological model, it is ensured that the limited slurry forms a continuous filling layer in the high-permeability channel. In the later stage of low-permeability formations, the theoretical flow trend is used as the upper limit of the flow rate to prevent discontinuity in filling caused by pressure accumulation. Through the cycle of "state monitoring - parameter correction - flow rate control", effective deposition of slurry is achieved in the high-permeability zone, and the filling density is ensured in the low-permeability zone, thereby simultaneously improving material utilization efficiency and construction safety. Attached Figure Description

[0039] The invention will now be further described with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic diagram of a coal mine goaf filling method based on simulation technology according to the present invention;

[0041] Figure 2 This is a schematic diagram of a coal mine goaf filling system based on simulation technology according to the present invention. Detailed Implementation

[0042] 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.

[0043] Please see Figure 1 As shown, this invention is a method for filling coal mine goaf based on simulation technology, comprising the following steps:

[0044] S1. Construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into surface meshes. Determine whether the surface mesh is a candidate mesh based on the rock strata engineering parameters. Establish an optimization model for the grouting hole layout based on the candidate mesh and solve it to obtain the target mesh. The rock strata engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata.

[0045] S2, Predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as the fluid-structure interaction boundary to the three-dimensional geological model to construct the fluid-structure interaction model;

[0046] S3, input the density and viscosity parameters of the grout and the engineering parameters of the lower rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0 and simulate the fluid-structure interaction model, obtain the flow velocity field and pressure field at the simulated grouting hole outlet, and transmit the fluid pressure to different areas of the lower rock layer in the target area through the fluid-structure interaction interface;

[0047] S4, obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, then generate a simulation flow rate sequence by gradually decreasing the initial simulated grouting flow rate V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow rate V1.

[0048] S4. The grouting filling thickness of the target area is obtained at intervals, and the corrected grouting flow rate V' is calculated based on the grouting filling thickness H. The grouting flow rate of the current grouting device is adjusted to V'.

[0049] It is worth noting that the dynamic impact force during the filling process, as the instantaneous mechanical action generated when the grout contacts the goaf floor in the initial filling stage, has significant instantaneous, pulsating, and locally concentrated characteristics. When there are uneven areas such as cracks and depressions in the floor, it can easily lead to cracking or spalling of weak rock surfaces, becoming a potential cause of early floor instability. Focusing on the mechanical risks of this specific stage can more accurately quantify the correlation between parameters such as grout flow rate, density, and grouting orifice diameter and dynamic impact intensity. By identifying key influencing factors, it can provide insights for optimizing the grouting process (such as adjusting the grouting pressure to control the flow rate and selecting appropriate orifice diameters to reduce local impact). This provides direct evidence; simultaneously, it allows for targeted assessment of the floor's weak areas (such as weak interlayers and cracked zones) to withstand instantaneous impacts, enabling pre-treatment measures (such as local reinforcement) to be taken in advance to avoid early damage accumulation caused by dynamic impacts, thereby ensuring the immediate stability of the floor during the filling process. In the actual grouting process, attention needs to be paid to the pressure on the top plate in the target area. Based on the monitoring results of the top plate pressure, the grouting pressure is dynamically adjusted to avoid top plate instability due to pressure superposition. In the actual application of this invention, the top plate pressure is monitored by default. If the top plate pressure is too high, the grouting flow rate of the grouting device is automatically reduced, which will not be elaborated further here.

[0050] It is worth noting that the grout flows within the grouting pipe (driven by pump pressure, belonging to pipe flow), while the movement of the grout within the goaf cavity after exiting the grouting pipe is either jet formation or free fall. The grouting flow velocity determined in this invention is the initial velocity of the grout leaving the grouting pipe. After leaving the grouting pipe, the grout can be approximated as free fall. Therefore, while maintaining the same impact force, it can be determined that V1 2 +2gh1=V'2+2gh', and then calculate to get Where g is the acceleration due to gravity, h1 is the expected fill height, and h' is the remaining fill height, then (h1-h') represents the actual fill thickness.

[0051] It is worth noting that in high-permeability strata (such as gravel layers), grout tends to flow rapidly along high-permeability channels. When the correction formula is E' = E * J * A, the sedimentation state coefficient J is positively correlated with the grout sedimentation rate: in high-permeability areas, the grout has strong fluidity and slow sedimentation, and the J value (0-1) is relatively small. Therefore, the corrected grouting volume E' decreases significantly as J decreases, and the actual grouting flow rate V" also decreases accordingly. By comparing the "theoretical flow trend," the final flow rate is determined, forming a dual flow-limiting effect of "grouting volume reduction + flow rate adaptation." In low-permeability strata (such as clay layers), the grout diffusion resistance is high, and it is easy for "…" to occur. "Underfilling" or pipe stagnation occurs. In this case, the grout dewaters quickly and settles rapidly, significantly increasing the J value (>1), making the calculated result of E' = E*J*A greater than the initial grouting volume E. Combined with the filling thickness requirement of H = E' / cross-sectional area, the grouting flow rate V' will be automatically increased within the device flow rate range [N,M], forming a pressurization mechanism of "increased grouting volume + increased flow rate". This strategy overcomes low permeability resistance and promotes the filling of fine pores by using J to provide real-time feedback on the grout viscosity.

[0052] In a preferred embodiment of the present invention, the specific process for determining the candidate mesh in step S1 is as follows:

[0053] The rock stratum engineering parameters of each surface grid are normalized, and the candidate score of each surface grid is calculated according to the formula W=d*Q+c*K. If the candidate score of any surface grid is greater than or equal to the preset threshold, the surface grid is marked as a candidate grid; where d and c are preset unit coefficients, Q is the rock stratum compressive strength, and K is the permeability coefficient.

[0054] By quantitatively evaluating multi-dimensional rock strata parameters, key indicators such as overlying strata thickness, compressive strength, and permeability coefficient are transformed into comparable values, avoiding the one-sidedness of single-parameter evaluation and thus accurately identifying rock strata areas requiring key attention. The advantages are twofold: firstly, comprehensively considering the permeability coefficient K allows for the priority identification of high-permeability-risk areas, providing targeted locations for subsequent grouting hole layout and preventing ineffective grout loss in high-permeability channels; secondly, combining overlying strata thickness and compressive strength allows for the assessment of formation bearing capacity, ensuring that candidate grids meet both the necessity of grouting and filling and possess construction feasibility. Ultimately, this lays the foundation for establishing an optimized grouting hole layout model, enabling the subsequently solved target grid to balance drilling efficiency and filling safety, and promoting precise control of the entire goaf filling scheme.

[0055] In another preferred embodiment of the present invention, the process of determining the target mesh in S1 is as follows:

[0056] With the objective functions of minimizing the total borehole length and maximizing the risk area coverage, real-number encoding is used to generate an initial gene population from the three-dimensional coordinates and borehole status of the candidate grid. The borehole space is optimized by randomly selecting parent individuals to perform continuous gene fragment exchange and recombination. Random offsets are applied to the coordinates of non-critical boreholes with a preset low probability. After each generation iteration, an elite retention mechanism is activated to eliminate the worst individuals. The surface grid corresponding to the globally optimal fitness individual is extracted as the target grid.

[0057] By leveraging the global search capability of a genetic algorithm, the optimal solution balancing drilling economy and filling safety is found among candidate grids. On one hand, minimizing the total borehole length directly reduces construction costs and the amount of drilling work; on the other hand, maximizing the coverage of risk areas ensures that dangerous areas such as high permeability or high stress are effectively covered by grouting holes, avoiding filling blind spots. This method uses operations such as gene recombination, random offset, and elite retention to continuously approach the optimal solution in the iterative optimization of the borehole layout. The final target grid ensures that grouting holes achieve precise coverage of risk areas with minimal drilling, laying the foundation for subsequent uniform grout filling and goaf stability control, and promoting a balance between construction efficiency and engineering safety in the entire filling scheme.

[0058] In another preferred embodiment of the present invention, the specific process for obtaining the filling thickness in step S5 is as follows:

[0059] Within a preset monitoring period, the relative permittivity of the grout in the filling area is acquired and input into a preset relative permittivity-sedimentation coefficient curve to obtain the sedimentation coefficient of the grout in the filling area. Based on the sedimentation coefficient, the amount of grout in the monitoring period is corrected to obtain the corrected grout amount. The cross-sectional area of ​​the grouting area is determined based on a three-dimensional geological model. The corrected grout amount and the cross-sectional area of ​​the grouting area are coupled and calculated to obtain the grouting filling thickness H.

[0060] Because the grout undergoes state changes due to sedimentation during the filling process, its relative dielectric constant changes with the degree of sedimentation. By measuring the dielectric constant and combining it with a preset curve, the sedimentation coefficient can be quickly obtained, reflecting the actual state of the grout. Correcting the grout volume based on the sedimentation coefficient can avoid the deviation between the theoretical output and the actual effective volume caused by sedimentation, making the grout volume calculation more closely match the actual filling requirements. Furthermore, determining the cross-sectional area and calculating the filling thickness through a three-dimensional geological model can intuitively reflect the actual progress of the filling, providing a specific basis for subsequent adjustments to the grouting flow rate. The advantages of this approach are that it enables real-time monitoring and quantitative evaluation of the grout state, making the calculation of grout volume and filling thickness more accurate; its purpose is to provide reliable data support for flow rate adjustment by dynamically capturing the changes caused by grout sedimentation; it plays a key role in solving the problems of early grout waste and insufficient filling in the later stages caused by traditional fixed-flow-rate grouting, and improving the goal of efficient grout utilization. Through real-time feedback and correction, the grouting flow rate can be dynamically adapted to the filling state, ensuring a more reasonable and efficient filling process.

[0061] In another preferred embodiment of the present invention, the specific process for constructing the relative permittivity-precipitation coefficient curve is as follows:

[0062] S11. Uniquely number multiple standard samples of grouting slurry and record the corresponding sedimentation state parameters;

[0063] S12, by controlling the dehydration environment parameters, grout samples with different sedimentation states were prepared, and the sample volume shrinkage rate was obtained and a gradient distribution was formed;

[0064] S13, use a vector network analyzer to measure the relative permittivity of each sample within a preset frequency band, and obtain the measured permittivity value corresponding to the sample number;

[0065] S14, pair the volume shrinkage rate of each sample with the corresponding relative permittivity value to generate a discrete data point set, and establish a relative permittivity value-precipitation coefficient curve based on the set using a curve fitting algorithm.

[0066] Uniquely numbering and recording the sedimentation state parameters of each sample ensures traceability of its state and avoids data confusion. Preparing samples with different sedimentation states and creating a volume shrinkage gradient under controlled dehydration conditions simulates the varying degrees of sedimentation that occur over time during actual filling, providing a diverse sample base for establishing quantitative relationships. Using a vector network analyzer to measure the dielectric constant in a preset frequency band is crucial because the sedimentation state of the grout alters its internal structure and water content, and the dielectric constant is sensitive to these changes, serving as a characteristic parameter for characterizing the degree of sedimentation. Pairing the volume shrinkage rate with the dielectric constant and fitting them into a curve establishes a quantitative mapping relationship between the two. This allows for rapid acquisition of the corresponding sedimentation coefficient from the curve simply by measuring the relative dielectric constant of the grout during actual filling monitoring. The purpose of this series of operations is to build a monitoring tool that can reflect the sedimentation state of the grout in real time. When grouting is actually performed, the sedimentation coefficient can be determined by curve based on the monitored dielectric constant, and then the grout volume and grouting flow rate can be adjusted. This allows the grouting process to dynamically adapt to the time-dependent sedimentation characteristics of the grout, avoiding the problems of early grout loss and insufficient filling in the later stages caused by traditional fixed flow rate grouting. Ultimately, this achieves precise and efficient filling of coal mine goaf areas, ensuring filling quality and engineering safety.

[0067] In another preferred embodiment of the present invention, the specific process for correcting the grout volume is as follows:

[0068] The grouting orifice diameter S of the output device is obtained in advance. The theoretical output grout volume is calculated according to the calculation formula E = V1 * T * S. The sedimentation coefficient J corresponding to the grout in the filling area is obtained. The sedimentation coefficient is multiplied by the theoretical output grout volume to obtain the corrected grout volume E'.

[0069] In another preferred embodiment of the present invention, step S5 further includes calculating according to the formula. The actual grouting flow rate V” is calculated. If the actual grouting flow rate V” is less than the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V”; if the actual grouting flow rate V” is greater than or equal to the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V’.

[0070] It is understandable that in high-permeability strata (such as gravel layers), grout tends to flow rapidly along high-permeability channels. When the correction formula is E' = E * J * A, the sedimentation state coefficient J is positively correlated with the grout sedimentation rate: in high-permeability areas, the grout has strong fluidity and slow sedimentation, and the J value (0-1) is relatively small. Therefore, the corrected grouting volume E' decreases significantly as J decreases, and the actual grouting flow velocity V” also decreases accordingly. By comparing the "theoretical flow trend" to determine the final flow velocity, a dual flow-limiting effect of "grouting volume reduction + flow velocity adaptation" is formed. In low-permeability strata (such as clay layers), the grout diffusion resistance is high, and sedimentation is prone to occur. "Underfilling" or pipe stagnation occurs. In this case, the grout dewaters rapidly, leading to accelerated sedimentation and a significant increase in the J value (>1). This results in the calculated value of E' = E * J * A being greater than the initial grouting volume E. Combined with the filling thickness requirement of H = E' / cross-sectional area, the grouting flow rate V' will be automatically increased within the device's flow rate range [N, M], forming a pressurization mechanism of "increased grouting volume + increased flow rate." This strategy, through real-time feedback of grout viscosity via J, overcomes low permeability resistance and propels the grout to fill fine pores.

[0071] In another preferred embodiment of the present invention, step S5 further includes obtaining the grouting flow rate range [N, M] of the current grouting device; if there is a current corrected grouting flow rate V' greater than M, then the grouting flow rate of the current grouting device is adjusted to M; if the grouting filling thickness H is greater than or equal to a preset thickness threshold, then the grouting flow rate of the current grouting device is not adjusted, and the grouting flow rate of the current grouting device is adjusted to N.

[0072] Obtaining the flow rate range of the grouting device and setting adjustment rules is to incorporate physical limitations of the equipment into the technical solution, avoiding pump overload, pipeline rupture, and other malfunctions caused by theoretically calculated corrected flow rates exceeding equipment capacity. When V' is greater than M, it is forcibly adjusted to M to ensure safe equipment operation and prevent mechanical damage caused by excessive flow rates. When the grouting filling thickness H reaches a preset threshold, the flow rate is adjusted to N (or the minimum flow rate). This aims to maintain system operation or prepare for shutdown at the minimum flow rate when the filling task is almost completed, avoiding grout waste due to over-grouting and preventing grout solidification and blockage in the pipeline due to sudden shutdown. This mechanism, through dual control of equipment capacity constraints and filling status judgment, ensures that the grouting flow rate meets the dynamic requirements of geological conditions without exceeding the equipment safety boundaries. Ultimately, it ensures that the goaf filling project accurately achieves the designed filling thickness under the premise of reliable equipment operation, avoiding resource waste and construction risks, and improving the overall safety and economy of the project.

[0073] according to Figure 2 The present invention also includes a coal mine goaf filling system based on simulation technology, used in the above-mentioned coal mine goaf filling method based on simulation technology, comprising:

[0074] The target acquisition module is used to construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into a surface mesh. Based on the rock engineering parameters of the surface mesh, it determines whether it is a candidate mesh. Based on the candidate mesh, it establishes an optimization model for the layout of grouting holes and solves it to obtain the target mesh. The rock engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata.

[0075] The model building module is used to predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as fluid-structure interaction boundaries to the three-dimensional geological model to build a fluid-structure interaction model.

[0076] The simulation calculation module is used to input the density and viscosity parameters of the grout and the engineering parameters of the underlying rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0, and simulate the fluid-structure interaction model to obtain the flow velocity field and pressure field at the outlet of the simulated grouting hole, and transmit the fluid pressure to different areas of the underlying rock layer in the target area through the fluid-structure interaction interface.

[0077] The flow velocity determination module is used to obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, the simulated flow velocity sequence is generated by gradually decreasing from the initial simulated grouting flow velocity V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow velocity V1.

[0078] The flow rate correction module is used to obtain the grouting filling thickness of the target area at intervals, and calculate the corrected grouting flow rate V' based on the grouting filling thickness H, so as to adjust the grouting flow rate of the current grouting device to V'.

[0079] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for filling coal mine goaf based on simulation technology, characterized in that, Includes the following steps: S1. Construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into surface meshes. Determine whether the surface mesh is a candidate mesh based on the rock strata engineering parameters. Establish an optimization model for the grouting hole layout based on the candidate mesh and solve it to obtain the target mesh. The rock strata engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata. S2, Predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as the fluid-structure interaction boundary to the three-dimensional geological model to construct the fluid-structure interaction model; S3, input the density and viscosity parameters of the grout and the engineering parameters of the lower rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0 and simulate the fluid-structure interaction model, obtain the flow velocity field and pressure field at the simulated grouting hole outlet, and transmit the fluid pressure to different areas of the lower rock layer in the target area through the fluid-structure interaction interface; S4, obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, then generate a simulation flow rate sequence by gradually decreasing the initial simulated grouting flow rate V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow rate V1. S5, obtain the grouting filling thickness of the target area at intervals, and calculate the corrected grouting flow rate V' based on the grouting filling thickness H, and adjust the grouting flow rate of the current grouting device to V'.

2. The method for filling coal mine goaf based on simulation technology according to claim 1, characterized in that, In S1, the specific process for determining the candidate grid is as follows: The rock strata engineering parameters of each surface grid are normalized. The normalized rock strata parameters are then weighted and summed to obtain the candidate score for each surface grid. If any surface grid has a candidate score greater than or equal to a preset threshold, then that surface grid is designated as a candidate grid.

3. The method for filling coal mine goaf based on simulation technology according to claim 1, characterized in that, In S1, the process of determining the target mesh is as follows: With the objective functions of minimizing the total borehole length and maximizing the risk area coverage, real-number encoding is used to generate an initial gene population from the three-dimensional coordinates and borehole status of the candidate grid. The borehole space is optimized by randomly selecting parent individuals to perform continuous gene fragment exchange and recombination. Random offsets are applied to the coordinates of non-critical boreholes with a preset low probability. After each generation iteration, an elite retention mechanism is activated to eliminate the worst individuals. The surface grid corresponding to the globally optimal fitness individual is extracted as the target grid.

4. The method for filling coal mine goaf based on simulation technology according to claim 1, characterized in that, In step S5, the specific process for obtaining the filling thickness is as follows: Within a preset monitoring period, the relative permittivity of the grout in the filling area is acquired and input into a preset relative permittivity-sedimentation coefficient curve to obtain the sedimentation coefficient of the grout in the filling area. Based on the sedimentation coefficient, the amount of grout in the monitoring period is corrected to obtain the corrected grout amount. The cross-sectional area of ​​the grouting area is determined based on a three-dimensional geological model. The corrected grout amount and the cross-sectional area of ​​the grouting area are coupled and calculated to obtain the grouting filling thickness H.

5. A method for filling coal mine goaf based on simulation technology according to claim 4, characterized in that, The specific process for constructing the relative permittivity-precipitation coefficient curve is as follows: S11. Uniquely number multiple standard samples of grouting slurry and record the corresponding sedimentation state parameters; S12, by controlling the dehydration environment parameters, grout samples with different sedimentation states were prepared, and the sample volume shrinkage rate was obtained and a gradient distribution was formed; S13, use a vector network analyzer to measure the relative permittivity of each sample within a preset frequency band, and obtain the measured permittivity value corresponding to the sample number; S14, pair the volume shrinkage rate of each sample with the corresponding relative permittivity value to generate a discrete data point set, and establish a relative permittivity value-precipitation coefficient curve based on the set using a curve fitting algorithm.

6. A method for filling coal mine goaf based on simulation technology according to claim 4, characterized in that, The specific process for correcting the grout volume is as follows: The grouting orifice diameter S of the output device is obtained in advance. The theoretical output grout volume is calculated according to the calculation formula E = V1 * T * S. The sedimentation coefficient J corresponding to the grout in the filling area is obtained. The sedimentation coefficient is multiplied by the theoretical output grout volume to obtain the corrected grout volume E'.

7. A method for filling coal mine goaf based on simulation technology according to claim 1, characterized in that, S5 further includes calculating the actual grouting flow rate V” based on the corrected grout volume E’. If the actual grouting flow rate V” is less than the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V”; if the actual grouting flow rate V” is greater than or equal to the corrected grouting flow rate V’, the grouting flow rate of the current grouting device is adjusted to V’.

8. A method for filling coal mine goaf based on simulation technology according to claim 7, characterized in that, S5 further includes obtaining the grouting flow rate range [N, M] of the current grouting device. If the current corrected grouting flow rate V' is greater than M, the grouting flow rate of the current grouting device is adjusted to M. If the grouting filling thickness H is greater than or equal to the preset thickness threshold, the grouting flow rate of the current grouting device is not adjusted, and the grouting flow rate of the current grouting device is adjusted to N.

9. A coal mine goaf filling system based on simulation technology, used to implement the coal mine goaf filling method based on simulation technology according to any one of claims 1-8, characterized in that, include: The target acquisition module is used to construct a three-dimensional geological model of the target area and divide the three-dimensional geological model into a surface mesh. Based on the rock engineering parameters of the surface mesh, it determines whether it is a candidate mesh. Based on the candidate mesh, it establishes an optimization model for the layout of grouting holes and solves it to obtain the target mesh. The rock engineering parameters include the compressive strength and permeability coefficient of the overlying rock strata. The model building module is used to predetermine the grouting location, grouting hole diameter and burial depth on the target grid, and map them as fluid-structure interaction boundaries to the three-dimensional geological model to build a fluid-structure interaction model. The simulation calculation module is used to input the density and viscosity parameters of the grout and the engineering parameters of the underlying rock layer in the target area into the fluid-structure interaction model, determine the initial simulated grouting flow velocity V0, and simulate the fluid-structure interaction model to obtain the flow velocity field and pressure field at the outlet of the simulated grouting hole, and transmit the fluid pressure to different areas of the underlying rock layer in the target area through the fluid-structure interaction interface. The flow velocity determination module is used to obtain the dynamic pressure peak value of different regions of the lower rock layer in the target area. If the pressure peak value of any region of the lower rock layer is greater than the preset maximum dynamic pressure threshold, the simulated flow velocity sequence is generated by gradually decreasing from the initial simulated grouting flow velocity V0. The first Vi in the sequence that satisfies that the dynamic pressure peak value of all different regions of the lower rock layer is less than or equal to the preset maximum dynamic pressure threshold is calibrated as the initial grouting flow velocity V1. The flow rate correction module is used to obtain the grouting filling thickness of the target area at intervals, and calculate the corrected grouting flow rate V' based on the grouting filling thickness H, so as to adjust the grouting flow rate of the current grouting device to V'.

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