Goaf gangue grouting filling quantity prediction method and system

Abstract

The application discloses a goaf gangue grouting filling quantity prediction method and system, and relates to the technical field of computer simulation design. The method constructs a space calculation model based on goaf space detection data, drilling trajectory and gangue grout parameters, determines the reachable area of two grouting drillings and candidate subareas; obtains single-hole reference response and pipeline and shaft pressure loss, performs bidirectional equal flow transfer when the total grouting flow is stable, corrects the orifice pressure sequence to obtain cross pressure response; solves the common grouting proportion of the candidate subareas according to the cross pressure response, determines the common grouting space, deducts the remaining accommodated volume according to the actual injection amount and gangue grout parameters, and obtains the remaining accommodated volume of the hole group in combination with the drilling exclusive space; and predicts the gangue grouting filling quantity of the hole group meeting the grouting end condition according to the planned grouting flow. The application eliminates the prediction deviation of repeated measurement of the common grouting space, and improves the simulation prediction reliability of the grouting filling quantity of multiple drillings.

Description

Technical Field

[0001] This application relates to the field of computer simulation design technology, specifically to a method and system for predicting the amount of gangue grouting and filling in goaf areas. Background Technology

[0002] Coal mining creates complex goaf spaces, which are often filled and treated using gangue grouting. In multi-bore collaborative grouting operations, the goaf contains cavities, collapsed deposits, fissures, and geological barriers, exhibiting complex spatial connectivity that dynamically changes as grouting progresses. Traditional methods rely on geological exploration, borehole exposure information, and on-site grouting pressure and flow rate measurements, combined with empirical formulas, to manually estimate the fillable space and expected filling volume. Some solutions also employ general numerical simulations to analyze grout diffusion.

[0003] Existing simulation estimation schemes have significant drawbacks: First, for simultaneous grouting of multiple boreholes, the diffusion areas of grout from different boreholes overlap. Traditional simulation models calculate the fillable space of each borehole separately and then directly summarize it, resulting in repeated measurement of overlapping common grouting spaces, causing significant deviations in the remaining fillable volume of the borehole group and the predicted filling volume. Second, the borehole pressure signals collected on-site are superimposed with pressure losses from the main pipeline, branch pipelines, and wellbore pipelines, as well as pressure changes caused by grout rheological properties and flow disturbances within the borehole itself. This makes it difficult to directly separate the cross-disturbance responses between different boreholes, resulting in the simulation model's inability to accurately identify the underground spatial connectivity between boreholes. Third, existing simulation models cannot iteratively correct model parameters using real-time measured pressure and flow data during the grouting process. The simulation calculation results deviate significantly from the actual filling state on-site, leading to insufficient reliability in the predicted timing of grouting termination and the amount of gangue used for filling, making it difficult to meet the digital simulation evaluation needs of multi-bore grouting processes in engineering sites.

[0004] Therefore, there is an urgent need for a computer numerical simulation processing scheme that can combine flow-pressure time series data collected by field sensors to invert and identify the common injection space of multiple boreholes, eliminate the calculation error caused by repeated measurement of overlapping spaces, dynamically update the state of the simulation model, and realize reliable simulation prediction of the grouting filling volume of the borehole group. Summary of the Invention

[0005] In view of this, this disclosure proposes a method and system for predicting the amount of gangue grouting in goaf areas.

[0006] According to one aspect of this disclosure, a method for predicting the amount of gangue grouting and backfilling in goaf areas is provided, including: Based on the spatial exploration data of the goaf, the borehole trajectory and the current gangue slurry parameters, a spatial calculation model of the goaf is constructed to determine the reachable areas of the two grouting boreholes, and the intersection of the two reachable areas is divided into candidate sub-regions; The single-hole reference responses of two grouting boreholes are obtained when the other grouting borehole is closed, along with the pressure losses of the main pipeline, branch pipelines, and wellbore. When grouting occurs simultaneously in both boreholes and the total grouting flow rate is within the allowable deviation range, the reduced flow rate from one grouting borehole is transferred in equal amounts to the other grouting borehole, and the flow rate sequence and orifice pressure sequence are collected. The orifice pressure sequence is corrected based on the pressure loss and the single-hole reference response to obtain the cross-pressure response. The common injection ratio of each candidate sub-region is calculated based on the cross-pressure response to determine the common injection space. The remaining capacity of the common injection space is uniformly reduced according to the actual injection volume and the corresponding gangue slurry parameters, and then merged with the dedicated space of the two grouting boreholes to obtain the remaining capacity of the borehole group. Based on the remaining capacity of the borehole group, the current gangue slurry parameters, and the planned grouting flow rate, the gangue grouting filling volume of the borehole group when the grouting termination condition is reached is predicted.

[0007] In one possible implementation, the goaf spatial calculation model includes calculation units, slurry channels, and injection nodes; the initial accommodative volume is determined based on the planar area, effective height, and initial porosity of each calculation unit; slurry channels are established between spatially adjacent calculation units that are not blocked by complete coal pillars, continuous water-resistant layers, or consolidated backfill bodies; and the position where the borehole trajectory intersects with the calculation unit after entering the goaf is set as the injection node.

[0008] In one possible implementation, the determination of the reachable region includes: starting from the two injection nodes respectively, solving the slurry flow state based on the current flow initiation pressure difference of the gangue slurry, the flow resistance of each slurry channel and the allowable grouting pressure, and forming the reachable region of the corresponding grouting borehole by the calculation units that can be reached by the corresponding injection nodes; dividing the intersection of the two reachable regions into the candidate sub-regions according to spatial continuity, geological properties and slurry channel direction.

[0009] In one possible implementation, obtaining the pressure loss and the single-hole reference response includes: collecting the pressure loss of the main pipeline, the branch pipeline, and the wellbore at multiple flow points before the gangue slurry enters the goaf; sequentially closing one grouting borehole, performing short-term multi-flow-point injection tests on another grouting borehole, deducting the corresponding pressure loss, and combining each flow point with the corresponding underground inlet pressure to form the single-hole reference response.

[0010] In one possible implementation, the equal transfer includes: after the reference flow rates of the two grouting boreholes stabilize, first reducing the flow rate of one grouting borehole and increasing the flow rate of the other grouting borehole by an equal amount, restoring the reference flow rate, and then performing the reverse equal transfer; the allowable deviation range is determined based on the measurement uncertainty of the two branch flow meters and the main pipeline total flow meter, as well as the fluctuation of the total grouting flow rate during the reference stage.

[0011] In one possible implementation, obtaining the cross-pressure response includes: subtracting the pressure loss of the corresponding main pipeline, branch pipeline and wellbore from the orifice pressure sequence, and then subtracting the underground inlet pressure change caused by the flow rate change of the corresponding grouting borehole based on the single-hole reference response of the corresponding grouting borehole; and determining the data segment in which the obtained residual pressure change continuously exceeds three times the standard deviation of the reference noise of the corresponding pressure sensor and lasts for no less than two pressure time windows as the effective cross-pressure response.

[0012] In one possible implementation, the solution for the common injection ratio includes: setting a common injection ratio with a value range of zero to one for each candidate sub-region; inputting the flow sequence into the goaf spatial calculation model; calculating the predicted underground inlet pressure of the two grouting boreholes; establishing an objective function based on the normalized deviation between the predicted underground inlet pressure and the measured underground inlet pressure after deducting the pressure loss; and solving for each common injection ratio through bounded iteration.

[0013] In one possible implementation, the bounded iteration employs a bounded finite-memory quasi-Newton method, solving the problem with multiple different initial values ​​and selecting the solution that minimizes the objective function. The minimum objective function value plus a convergence threshold determined based on pressure noise is used as the upper limit of the acceptable objective function, and the upper and lower limits of the common injection ratios are determined from the solution results that satisfy the upper limit of the acceptable objective function.

[0014] In one possible implementation, the deduction of the remaining accommodating volume includes: dividing the common part and the non-common part according to the common injection ratio of each candidate sub-region; recording the source of the grout entering the same common part from the two grouting boreholes respectively, and allocating the source ratio according to the entering volume; converting the volume of the grout entering the same common part into the particle packing volume according to the corresponding gangue grout parameters, and deducting the remaining accommodating volume of the common part once.

[0015] According to another aspect of this disclosure, a system for predicting the amount of grout filling in goaf areas is provided, comprising: The spatial model construction module is used to construct a spatial calculation model of the goaf based on the spatial exploration data of the goaf, the borehole trajectory and the current gangue slurry parameters, determine the reachable area of ​​two grouting boreholes, and divide the intersection of the two reachable areas into candidate sub-regions; The cross-pressure response acquisition module is used to acquire the single-hole reference response of two grouting boreholes when the other grouting borehole is closed, as well as the pressure loss of the main pipeline, branch pipeline, and wellbore; when two grouting boreholes are grouting simultaneously and the total grouting flow rate is within the allowable deviation range, the flow rate reduction of one grouting borehole is transferred equally to the other grouting borehole, and the flow rate sequence and orifice pressure sequence are collected; the orifice pressure sequence is corrected according to the pressure loss and the single-hole reference response to obtain the cross-pressure response; The remaining accommodative volume determination module is used to solve the common injection ratio of each candidate sub-region based on the cross pressure response, and determine the common injection space; the remaining accommodative volume of the common injection space is uniformly deducted according to the actual injection volume and the corresponding gangue slurry parameters, and merged with the dedicated space of the two grouting boreholes to obtain the remaining accommodative volume of the borehole group; The filling volume prediction module is used to predict the filling volume of gangue grouting in the hole group when the grouting end conditions are met, based on the remaining accommodable volume of the hole group, the current gangue slurry parameters, and the planned grouting flow rate.

[0016] This application constructs a spatial calculation model based on spatial exploration data of the goaf, borehole trajectories, and gangue slurry parameters. It obtains the cross-pressure response through bidirectional equal flow transfer between two grouting boreholes. After deducting the pressure losses from pipelines and shafts, as well as the influence of borehole flow rate variations, it solves for the common injection ratio of candidate sub-regions, enabling the identification of underground connectivity between boreholes that is difficult to directly determine using actual grouting responses. Simultaneously, the common injection space is uniformly deducted as a shared space for the borehole group, and the injected volume is converted into particle accumulation volume and retained dry gangue mass according to actual slurry parameters, avoiding duplicate calculations of fillable space caused by separate statistics for multiple boreholes. As grouting progresses, the model can update the common injection ratio and slurry channel parameters based on new pressure and flow data, ensuring that the remaining fillable volume of the borehole group corresponds to the actual filling state. This improves the reliability of the predicted filling volume when grouting termination conditions are met, providing a basis for grout flow configuration, termination timing judgment, and gangue usage arrangement.

[0017] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0019] Figure 1 A flowchart is shown for a method for predicting the amount of gangue grouting in a goaf according to an embodiment of the present disclosure.

[0020] Figure 2A flowchart illustrating the candidate subregion partitioning process according to an embodiment of this disclosure is shown.

[0021] Figure 3 A flowchart illustrating the cross-pressure response acquisition process according to an embodiment of this disclosure is shown.

[0022] Figure 4 A flowchart illustrating the predicted grouting filling volume of the borehole group according to an embodiment of the present disclosure is shown.

[0023] Figure 5 A schematic diagram of a system for predicting the amount of grout filling in a goaf area according to an embodiment of the present disclosure is shown.

[0024] Figure 6 A schematic diagram of the structure of an electronic device according to an embodiment of the present disclosure is shown. Detailed Implementation

[0025] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0026] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0027] This implementation method is applicable to projects where caving zones, fracture zones, or delamination spaces have formed, and gangue slurry is injected into the goaf through surface vertical wells, directional wells, or cluster boreholes. A borehole group includes at least two independently adjustable grouting boreholes. Each grouting borehole branch is equipped with a flow meter, orifice pressure sensor, and regulating valve, while the main pipeline is equipped with a total flow meter. The field control system synchronously records flow rate, pressure, valve opening, slurry density, and solid mass concentration. Before implementation, goaf space exploration data, borehole trajectory, borehole diameter and casing information, as well as the current gangue slurry particle size distribution, density, solid mass concentration, yield stress, and viscosity are obtained. Calculations and inversions are performed by an on-site industrial computer, and valves and pump units are controlled by a programmable logic controller (PLC) with safety interlocks.

[0028] The implementation process of the method described in this application will be described in detail below with reference to specific embodiments. It should be noted that this embodiment is only used to explain this application and is not intended to limit the scope of protection of this application. Conventional adjustments or substitutions of each step by those skilled in the art without departing from the concept of this application should be included in the scope of protection of this application.

[0029] Figure 1 A flowchart illustrating a method for predicting the amount of gangue grouting and filling in a goaf according to an embodiment of this disclosure is shown. Figure 1As shown, the method may include: In step S11, a spatial calculation model of the goaf is constructed based on the goaf spatial exploration data, borehole trajectory and current gangue slurry parameters, the reachable areas of the two grouting boreholes are determined, and the intersection of the two reachable areas is divided into candidate sub-regions.

[0030] This step uses goaf spatial exploration data, borehole trajectories, and current gangue slurry parameters as inputs to form a goaf spatial calculation model, the reachable areas of the two grouting boreholes, and candidate sub-regions. In this embodiment, the goaf spatial calculation model refers to a numerical model composed of calculation units, slurry channels, and injection nodes. Here, a calculation unit represents a local goaf space, a slurry channel represents the connection between adjacent calculation units, and an injection node represents the intersection point between the borehole exit and the calculation unit.

[0031] like Figure 2 As shown, Figure 2 A flowchart of candidate sub-region partitioning according to an embodiment of the present disclosure is shown. In step S1101, spatial coordinates are unified and calculation units are generated.

[0032] According to embodiments of this disclosure, 3D seismic data, transient electromagnetic data, micromotion detection data, borehole leakage records, borehole television data, mining engineering plans, and borehole trajectories are unified into the same mining area coordinate system. Geophysical results are corrected for coordinates and elevations according to control points and checked against the borehole trajectory hole by hole; areas with both geophysical anomalies and borehole leakage records are marked as void development zones, and areas containing intact coal pillars, continuous aquitards, or consolidated filling bodies are marked as barrier zones.

[0033] The calculation units are divided according to the spatial variation scale. These units can be cuboids or irregular units set along the top and bottom of the coal seam and the borehole trajectory. The unit size is selected to distinguish residual void areas, collapsed rock accumulation areas, fracture concentration areas, and barrier areas. For example, if the working face has a planar range of 1000m x 300m and a vertical calculation height of 30m, an initial calculation unit of 10m x 10m x 2m is used; the area around the borehole within 20m and the boundary of geophysical anomalies are further subdivided into 5m x 5m x 1m units.

[0034] No. The initial accommodative volume of each computing unit is obtained according to the following formula:

[0035] in, For the first The initial accommodating volume of each computing unit, in units of ; To calculate the planar area of ​​the unit, the unit is... ; The effective height of the calculation unit, in units of ; This represents the initial porosity. For example, the planar area of ​​a certain computing cell is 100. With an effective height of 2m and an initial porosity of 0.32, the initial accommodative volume is 64. .

[0036] The initial porosity is determined at locations with borehole verification. Visible cavities are initially calculated as the ratio of the cavity height measured by borehole television to the effective height of the calculation unit. For areas with collapsed gangue accumulation, the initial value is calculated based on core block size, leakage, and the coefficient of fragmentation. Subsequently, a piecewise linear relationship between the geophysical anomaly intensity and the initial porosity is established within the same geological zone. When historical borehole data is unavailable, the calculated value based on the coefficient of fragmentation is used initially, and then corrected after single-hole grouting trials.

[0037] The initial value specifically refers to the first... The initial porosity used by each calculation unit at the start of the grouting calculation , used in accordance with Calculate the initial containment volume of this computational unit. For caved rock accumulation zones, first determine the coefficient of fragmentation based on the section exposed by the borehole. Calculate the porosity by converting the fragmentation:

[0038] in, It is the ratio of the total volume of the collapsed gangue to the volume of the corresponding gangue entity. The reference porosity is calculated from the coefficient of fragmentation.

[0039] Furthermore, regarding the first The equivalent particle size of each coring block in the core sampling section corresponding to each calculation unit is measured, and the median particle size is used. Characterize the core block size; obtain the cumulative leakage volume of the core segment from the borehole leakage record. and corresponding drilling length Calculate the leakage per unit advance:

[0040] Optionally, when verified borehole data exists in the same geological zone, the core block size benchmark value of that geological zone shall be used. and the benchmark value of leakage per unit advance The reference porosity is corrected as follows:

[0041] in, For the first Initial porosity values ​​for each computational unit; and These are the coring block size correction factor and the leakage correction factor, respectively, which are determined by fitting existing borehole verification data from the same geological zone. and These are the lower and upper limits of the initial porosity obtained from existing borehole verification in this geological zone, respectively. This indicates that the calculation results will be limited to the upper and lower limits. In specific implementation, the results will first be determined according to the depth of the core section and the location of the lost records. , Spatially match the corresponding calculation unit, and then substitute it into the above formula to obtain the initial porosity value of the calculation unit. If there is no historical borehole group data, do not perform statistical corrections for core block size and leakage; directly use:

[0042] As the initial value for porosity; after completing the single-hole injection test, the model-predicted underground inlet pressure is compared with the measured underground inlet pressure, and the corresponding geological zones are analyzed based on the deviation between the two. After correction, the initial containment volume of each computational unit is calculated using the corrected initial porosity. In step S1102, slurry channels are established and the current gangue slurry parameters are written. When two computational units are spatially adjacent and there is no obstruction zone, a slurry channel is established between them. Each slurry channel records its channel length, equivalent width, effective size, flow initiation pressure difference, and flow resistance. The effective size refers to the equivalent channel height that controls the current gangue slurry and the passage capacity of its coarse particles; for interlayer fractures, the equivalent value of the fracture aperture is taken; for caving gangue pores, the equivalent value of the main pore throat size between blocks is taken.

[0043] The current gangue slurry does not flow along the corresponding slurry channel before reaching the initial flow pressure differential. After reaching the initial flow pressure differential, the channel flow rate is calculated using the following formula:

[0044] in, For the first The computing unit and the first Channel flow between computing units, in units of ; and These are the pressures of the two calculation units, in units of ; The initial pressure difference at the start of flow is expressed in units of... ; Flow resistance, unit: .

[0045] The initial pressure differential for flow is obtained based on the current yield stress of the gangue slurry and the slurry channel structure:

[0046] in, The yield stress of the current gangue slurry is given in units of 1. ; The length of the slurry channel, in units of ; Effective dimensions, in units of For example, when the yield stress is 18 Pa, the slurry channel length is 12 m, and the effective size is 0.06 m, the initial pressure difference for flow is 7200 Pa.

[0047] Flow resistance is calibrated through loop tests, representative fracture tests, or single-hole injection tests. Specifically, after reaching the flow state, the pressure difference across the slurry channel is subtracted from the initial flow pressure difference, and then divided by the corresponding channel flow rate. For example, a representative slurry channel might have a pressure difference of 32000 Pa, an initial flow pressure difference of 8000 Pa, and a channel flow rate of 0.004 Pa. The flow resistance is 6,000,000. The same type of calibration value is used within the same geological zone, and is corrected proportionally according to the length of the slurry channel.

[0048] The borehole trajectory is matched point by point with the calculation unit. The position where the borehole trajectory enters the goaf and intersects with the calculation unit is set as the injection node. The well depth, borehole diameter, bare borehole length and trajectory inclination are retained for vertical wells and directional wells respectively. The wellbore pressure loss is recorded separately and is not included in the flow resistance of the slurry channel.

[0049] In step S1103, the reachable region and candidate sub-regions are determined. Starting from the two injection nodes, the flow state of each slurry channel is solved within the current flow initiation pressure difference of the gangue slurry and the allowable grouting pressure range. If the cumulative pressure difference required to reach a certain calculation unit from an injection node along a continuous slurry channel does not exceed the remaining pressure after deducting the pressure loss of the corresponding pipeline and wellbore from the allowable grouting pressure, then the calculation unit is included in the reachable region of the corresponding grouting borehole.

[0050] For example, the solution to the flow state of each slurry channel is achieved using a general-purpose iterative solver for sparse nonlinear equations based on the Newton-Raphson method. Specifically, for each computational unit i in the goaf spatial computational model, nodal equilibrium equations are established based on mass conservation:

[0051] in, It is the set of all computing units adjacent to computing unit i; The flow rates for channels i and j are calculated using the formulas described in the preceding steps. Let be the pressure at node i, and be the unknown quantity to be determined. The boundary conditions are: the flow rate at the injection node is known (equal to the grouting borehole flow rate), and the pressure in the edge calculation elements is hydrostatic pressure. The solver uses the Newton-Raphson method with backtracking search, and its iteration format is:

[0052] in, is the Jacobian matrix of the mass conservation equations, and its sparsity mode is determined by the connectivity of the slurry channels. The step size is determined by the Armijo-Goldstein criterion. The construction of the Jacobian matrix and the solution of the linear equations are performed using the KLU decomposition algorithm from the open-source Suite Sparse library. The convergence criterion for the solver is: the absolute value of the mass conservation equation residuals at all nodes is less than... Or the relative change in pressure variables between two adjacent iterations is less than .

[0053] In one example, the allowable orifice pressure is 1.5 MPa, and the pressure loss in the pipeline and wellbore of a directional well at the current flow rate is 0.32 MPa. Therefore, the available pressure in the underground space is 1.18 MPa. The program expands outward from the injection node. For one path, the cumulative initial pressure difference and flow pressure difference are 1.06 MPa, and the corresponding calculation unit is included in the reachable region. For another path, the cumulative pressure difference is 1.24 MPa, and the corresponding calculation unit is not included in the reachable region.

[0054] The intersection of two reachable regions is considered as a candidate common injection region, and further divided into candidate sub-regions based on spatial continuity, geological properties, and slurry channel direction. A candidate sub-region refers to a group of computational units that are continuously adjacent within the intersection, have the same geological properties, and share the same main slurry channel direction. Whether a sub-region belongs to the common injection space is determined by the cross-pressure response.

[0055] The geological attributes mentioned herein, for the goaf space, include at least the following three categories: 1) residual void areas; 2) collapsed rock accumulation areas; and 3) concentrated fissure areas. The criteria for determining identical geological attributes are: spatial continuity and belonging to the same category as described above.

[0056] The consistent orientation of the main slurry channels means that the weighted average direction of the orientation vectors of all slurry channels connecting each computational unit within the candidate sub-region forms an angle of less than 45 degrees with the overall orientation of the sub-region. The orientation vector of the slurry channel is determined by the difference in coordinates between the centers of the computational units at both ends of the channel, with the weight being the effective size of the channel.

[0057] For example, there are 420 computational units in the intersection. The geological properties of the eastern fissure concentration area, the central collapsed gangue accumulation area, and the western residual cavity area are different, thus forming three candidate sub-regions respectively.

[0058] In step S12, the single-hole reference response and pressure loss of the two grouting boreholes are obtained, and the flow rate is transferred in equal amounts and the cross pressure response is obtained when the total grouting flow rate is within the allowable deviation range.

[0059] Specifically, the single-hole reference responses of the two grouting boreholes are obtained when the other grouting borehole is closed, as well as the pressure losses of the main pipeline, branch pipeline, and wellbore. When the two grouting boreholes are grouting simultaneously and the total grouting flow rate is within the allowable deviation range, the reduced flow rate of one grouting borehole is transferred to the other grouting borehole in equal amounts, and the flow rate sequence and orifice pressure sequence are collected. The orifice pressure sequence is corrected according to the pressure loss and the single-hole reference response to obtain the cross pressure response.

[0060] This step uses the spatial calculation model of the goaf, two grouting boreholes, and their surface pipelines as the objects. First, it obtains the single-hole baseline response and pressure loss. Then, when the total grouting flow rate is within the allowable deviation range, it performs a bidirectional flow rate transfer. The single-hole baseline response refers to the underground inlet pressure of this grouting borehole at different flow rates when the other grouting borehole is closed. The cross-pressure response refers to the residual pressure change caused by the flow rate change of the other grouting borehole after deducting the pressure loss and the influence of the flow rate change of this grouting borehole itself.

[0061] Specifically, such as Figure 3 As shown, Figure 3 A flowchart of cross-pressure response acquisition according to an embodiment of the present disclosure is shown. In step S1201, the pressure loss of the main pipeline, branch pipeline and wellbore is obtained.

[0062] Before the gangue slurry enters the goaf, a pipeline circulation test should be conducted, or a short-term pumping test should be conducted under temporary isolation conditions at the borehole outlet. At least three flow points should be set on the main pipeline, two branch pipelines, and two shafts, covering the minimum and maximum flow rates of subsequent disturbances. Each flow point should be maintained until the pressure fluctuation enters a stable range, and the flow rate and pressure loss should be recorded to create a separate pressure loss lookup table.

[0063] The pressure stability condition is determined based on the reference noise of the pressure sensor, and the length is assumed to be... The average pressure within the pressure time window is The standard deviation of pressure is When three consecutive pressure time windows meet At that time, the current flow point enters a stable state. Among them, and The unit is , The unit is , The unit is For example, if the pressure time window is 30 seconds, the standard deviation of the reference noise is 2000 Pa, and the average pressure change within three consecutive pressure time windows does not exceed 6000 Pa, then the flow rate point is recorded.

[0064] Wherein, the pressure time window Used for data smoothing and stability assessment, its value should be greater than the correlation time of the main noise component in the pressure signal and less than the shortest response time of the grouting system. Specifically, the method is as follows: during the stable grouting stage when the grouting pump and valves are not operating, pressure data for no less than 10 minutes is collected, its power spectral density is calculated, and the reciprocal of the frequency corresponding to the point where the power spectral density drops to 10% of its low-frequency (<0.01Hz) average value is taken as the pressure time window. The initial value. In field implementation, if spectrum analysis is inconvenient, the default value is used. .

[0065] During actual grouting, linear interpolation of adjacent flow points is performed based on the real-time flow rate in a pressure loss lookup table. For example, for a branch line at 50... and 70 The pressure losses at the two times were 0.08 MPa and 0.13 MPa, respectively, and the real-time flow rate was 60. The corresponding pressure loss is 0.105 MPa.

[0066] In step S1202, the single-hole reference responses of the two grouting boreholes are obtained. After pressure loss calibration is completed, the second grouting borehole is closed, and a short-term test injection at multiple flow points is performed on the first grouting borehole; subsequently, the first grouting borehole is closed, and the same test injection is performed on the second grouting borehole. The current gangue slurry is still used at each flow point until the aforementioned pressure stability condition is met. After deducting the pressure losses of the main pipeline, corresponding branch pipeline, and corresponding wellbore from the borehole pressure, the underground inlet pressure is obtained; each flow point is mapped one-to-one with the underground inlet pressure to form a single-hole reference response lookup table for the corresponding grouting borehole.

[0067] The cumulative injection volume of short-term test injections should not alter the state of the candidate common injection area. Specifically, the pressure changes corresponding to multiple test injection volumes are first calculated using a goaf spatial calculation model. The largest test injection volume, whose predicted pressure change does not exceed three standard deviations of the corresponding pressure sensor's baseline noise, is selected. In one example, the initial accommodative volume of the candidate common injection area is 16,000. Model calculations show that injecting 80 The pressure change caused by the slurry is 0.004 MPa, while the standard deviation of the pressure sensor's reference noise is 0.006 MPa. Therefore, the single-hole test injection volume is taken as 80. .

[0068] For example, the first grouting boreholes are at 40, 60, and 80. At the three flow points, the underground inlet pressures, after deducting pressure loss, were 0.31, 0.47, and 0.68 MPa, respectively; the corresponding values ​​for the second grouting borehole were 0.35, 0.53, and 0.76 MPa, respectively. During subsequent disturbances, if the real-time flow rate of the first grouting borehole is 50... The single-hole reference underground inlet pressure was found to be 0.39 MPa by linear interpolation of adjacent flow points.

[0069] In step S1203, the allowable deviation range and disturbance amount of the total grouting flow rate are determined. Two grouting boreholes are simultaneously grouted at the reference flow rate, and the total flow rate of the main pipeline is the sum of the flow rates of the two branch pipelines.

[0070] in, The total grouting flow rate, and These represent the branch flow rates of the two grouting boreholes, in units of... .

[0071] The permissible deviation range is determined based on the measurement uncertainties of the two branch flow meters, the main flow meter, and the fluctuation of the total grouting flow rate during the baseline stage:

[0072] in, , and These represent the absolute measurement uncertainties of the flow meters on the two branch lines and the total flow meter on the main line, respectively, in units of... ; The standard deviation of the total grouting flow rate at the baseline stage is given in units of... ; The average total grouting flow rate at the baseline stage, in units of ; This is the allowable deviation ratio. During the disturbance period, only data that satisfies the following formula will be processed further:

[0073] For example, the absolute measurement uncertainties of the two branch flow meters and the main flow meter are 0.6, 0.6, and 0.8, respectively. The average total grouting flow rate at the baseline stage is 120. The standard deviation of the total grouting flow rate is 0.5. The measurement uncertainty corresponds to a proportion of 1.00%, and the 3-fold fluctuation corresponds to a proportion of 1.25%. Therefore, the allowable deviation proportion is taken as 1.25%.

[0074] The disturbance is limited by both flow rate identifiability and pressure margin. The lower limit of the disturbance is five times the combined standard deviation of the flow-noise ratio of the two branches.

[0075] in, , and All units are The upper limit of the disturbance is taken as the smaller value between the flow rate corresponding to the local linear range of the single-orifice reference response and the flow rate corresponding to the pressure margin.

[0076] in, The maximum relative flow rate change that maintains local linearity in the single-orifice reference response; To allow orifice pressure, the unit is... ; The larger of the two grouting borehole reference pressures, in units of ; This represents the maximum ratio of pressure increment to flow rate increment during a single-hole injection test, expressed in units of... .

[0077] The local linear range was calibrated through single-orifice injection testing. The flow rate variation was progressively increased, and pressure was calculated using linear interpolation between adjacent flow points. When the difference between the interpolated pressure and the measured pressure first exceeded three times the standard deviation of the pressure sensor's reference noise, the previous flow rate variation ratio was taken as the threshold. In one example, The value is 0.1, and the baseline total grouting flow rate is 120. The disturbance amount converted from the pressure margin is 14. The upper limit of the disturbance is 12. The lower limit of the disturbance obtained from flow noise is 6. Finally, 9 were selected. .

[0078] In step S1204, a bidirectional equal-volume transfer is performed, and the flow rate sequence and orifice pressure sequence are acquired. After the reference flow rates of the two grouting boreholes stabilize, the flow rate of the first grouting borehole is reduced first, and the same flow rate is increased to the second grouting borehole; after restoring the reference flow rates of the two grouting boreholes, the flow rate of the first grouting borehole is increased again, and the same flow rate is reduced from the second grouting borehole. The total grouting flow rate is kept within the allowable deviation range during each disturbance stage.

[0079] The shortest duration of each stage is greater than the ratio of the effective volume of the branch between the regulating valve and the orifice to the corresponding branch flow rate. For example, the effective volume of the branch is 2.5. The branch road flow rate is 60 If the slurry is transported from the regulating valve to the orifice in 150s, then each stage must last at least 150s and continue until the pressure stabilization condition is met.

[0080] In one example, the reference flow rate for both grouting boreholes is 60. The total grouting flow rate is 120. The disturbance value is 10. During positive disturbance, the first grouting borehole is adjusted to 50. The second grouting borehole was adjusted to 70. After recovery, reverse disturbance is performed, and the first grouting borehole is adjusted to 70. The second grouting borehole was adjusted to 50. Pressure, flow rate, valve opening, slurry density, and solid mass concentration are sampled using the same clock, with a sampling frequency of, for example, 2 Hz.

[0081] The cumulative injection volume for a single disturbance stage is limited using the same method as for single-hole injection. The goaf spatial calculation model calculates the pressure change caused by the candidate disturbance volume, taking the maximum value not exceeding three standard deviations of the pressure sensor's reference noise. For example, the current remaining accommodateable volume of the candidate common injection area is 14,000. , Inject 28 The predicted pressure change caused by the slurry is 0.005 MPa, and the pressure sensor reference noise has a standard deviation of 3 times 0.006 MPa. Therefore, the cumulative injection volume in a single disturbance stage does not exceed 28. .

[0082] In step S1205, the orifice pressure sequence is corrected and the cross-pressure response is obtained. Specifically, firstly, the pressure loss of the main pipeline, corresponding branch pipeline, and corresponding wellbore is obtained from the pressure loss lookup table according to the real-time flow rate, and the pressure loss is subtracted from the orifice pressure sequence to obtain the measured underground inlet pressure sequence; then, according to the real-time flow rate of each grouting borehole, the underground inlet pressure change corresponding to the flow rate change of this grouting borehole is obtained from the single-hole reference response lookup table, and subtracted from the measured underground inlet pressure sequence, and the remaining pressure change is the cross-pressure response.

[0083] Taking positive disturbance as an example, the flow rate of the first grouting borehole is 60 Reduced to 50 The single-hole reference response indicates that the flow rate change will cause the underground inlet pressure of the first grouting borehole to decrease by 0.08 MPa; the actual underground inlet pressure after deducting pressure loss only decreases by 0.055 MPa. Therefore, the remaining 0.025 MPa is the cross pressure response of the second grouting borehole to the first grouting borehole caused by the increase in flow rate. The reverse disturbance is similar.

[0084] In one embodiment, the criteria for determining an effective cross-pressure response are consistent with the foregoing, namely, the residual pressure change continuously exceeds three times the standard deviation of the corresponding pressure sensor's reference noise for at least two pressure time windows. The response occurrence time is the moment when the residual pressure change first meets this condition after the disturbance command takes effect at the borehole. For example, if the standard deviation of the pressure sensor's reference noise is 0.002 MPa and the determination threshold is 0.006 MPa, and the residual pressure change in the first grouting borehole reaches 0.007 MPa at 85 s after a positive disturbance, and remains above 0.006 MPa for the following 60 s, then the response occurrence time is 85 s.

[0085] When both forward and reverse perturbations generate effective cross pressure responses, the effective data segments in both directions are retained; when only one direction generates an effective cross pressure response, only the effective data segment in that direction is retained, and in subsequent solutions, only the candidate sub-regions closest to that response direction are adjusted; when neither direction generates an effective cross pressure response, no new common injection space is added in this round.

[0086] In step S13, the common injection ratio of each candidate sub-region is calculated based on the cross pressure response, the remaining accommodative volume of the common injection space is uniformly deducted, and the amount of gangue grouting filling in the hole group when the grouting end condition is reached is predicted.

[0087] Specifically, the common injection ratio of each candidate sub-region is solved based on the cross-pressure response to determine the common injection space; the remaining accommodative volume of the common injection space is uniformly deducted according to the actual injection volume and the corresponding gangue slurry parameters, and merged with the dedicated space of the two grouting boreholes to obtain the remaining accommodative volume of the borehole group; based on the remaining accommodative volume of the borehole group, the current gangue slurry parameters, and the planned grouting flow rate, the gangue grouting filling volume of the borehole group when the grouting termination condition is reached is predicted.

[0088] This step takes candidate sub-regions, flow sequences, measured underground inlet pressure sequences, and cross-pressure responses as inputs to solve for the common injection ratio of each candidate sub-region, thereby forming a common injection space. The common injection ratio represents the proportion of the current remaining accommodative volume of a candidate sub-region that can be reached by either of the two grouting boreholes and is measured only once in the total number of boreholes in the borehole group, with a value ranging from 0 to 1.

[0089] Specifically, such as Figure 4 As shown, Figure 4 A flowchart illustrating the prediction of gangue grouting filling volume according to an embodiment of the present disclosure is shown. In step S1301, the common injection ratio is solved based on the cross pressure response.

[0090] In the spatial calculation model of the goaf, each candidate sub-region is divided into a common part and a non-common part. The volume of the common part is determined by the current remaining accommodative volume of the candidate sub-region and the common injection ratio; the non-common part is allocated according to the single-hole flow calculation results of the two grouting boreholes. If the cumulative flow rate of one grouting borehole entering the candidate sub-region is higher than that of the other grouting borehole, the non-common part is allocated to the former; if the difference in the cumulative flow rates does not exceed the combined uncertainty of the two branch flowmeters, the non-common part is allocated according to the ratio of the two cumulative flow rates.

[0091] The flow sequence collected in the preceding steps is input into the spatial calculation model of the goaf to calculate the predicted underground inlet pressure of the two grouting boreholes, and compared with the measured underground inlet pressure. The co-injection ratio is obtained by minimizing the following objective function:

[0092] in, This is a vector composed of the common injection proportions of all candidate subregions; This represents the number of valid sampling points. and The predicted underground inlet pressure for two grouting boreholes is given in units of... ; and The measured underground inlet pressures of the two grouting boreholes are given in units of... ; To allow orifice pressure, the unit is... .

[0093] For example, a bounded finite-memory quasi-Newton method (L-BFGS-B) is used to solve for the co-injection ratio. The algorithm inputs include the current remaining containment volume of the candidate sub-region, slurry channel parameters, flow rate sequence, and measured subsurface inlet pressure sequence. In each iteration, the algorithm changes the co-injection ratio, recalculates the predicted subsurface inlet pressure, and recalculates the objective function. The output is the co-injection ratio when the objective function is minimized. The lower bound of each co-injection ratio is 0, and the upper bound is 1.

[0094] For example, each candidate sub-region Current remaining capacity Split into common parts Non-common parts According to the aforementioned allocation rules, the corresponding volume increments (obtained by time integration of the flow sequence) are allocated to specific computational units of the spatial model. The steady-state flow network solver from the previous steps is then invoked to calculate the predicted underground inlet pressures of the two grouting boreholes under the current model state and injection flow rate. and Calculate the objective function. The L-BFGS-B algorithm updates the co-injection ratio based on the objective function value and gradient information (approximated by the finite difference method). Continue until the convergence condition is met.

[0095] In practical applications, the solution is obtained using three initial values: 0.2, 0.5, and 0.8. Each initial value is iterated a maximum of 200 times. The process stops when the change in the objective function after five consecutive iterations falls below a convergence threshold determined based on the pressure noise. The convergence threshold is set to... ,in, The larger of the two reference noise standard deviations of the grouting borehole pressure sensors is given, in units of For example, the allowable orifice pressure is 1.5 MPa, the maximum reference noise standard deviation is 0.002 MPa, and the convergence threshold is 0.00000533.

[0096] For example, the current remaining capacity of the three candidate sub-regions are 4200, 3600, and 2800, respectively. With an initial value of 0.2, the common betting ratios are 0.76, 0.45, and 0.14, with an objective function of 0.0018; with an initial value of 0.5, the ratios are 0.78, 0.46, and 0.12, with an objective function of 0.0012; with an initial value of 0.8, the ratios are 0.79, 0.44, and 0.13, with an objective function of 0.0015. Therefore, 0.78, 0.46, and 0.12 are selected as the results of this round of calculation.

[0097] In one embodiment, the minimum objective function value plus the convergence threshold is used as the acceptable upper limit of the objective function. Among feasible solutions that satisfy this upper limit, the minimum and maximum values ​​of each common injection ratio are obtained, forming the lower and upper limits of the common injection ratio. The number of candidate sub-regions does not exceed half of the total number of data segments that meet the pressure stability condition during the forward disturbance stage, the reverse disturbance stage, and the intermediate baseline flow recovery stage; if it exceeds this, adjacent candidate sub-regions with the same geological properties and consistent slurry channel direction are merged. For example, if a total of 8 data segments that meet the pressure stability condition are obtained, the number of candidate sub-regions does not exceed 4.

[0098] In step S1302, the common injection space is determined and the remaining accommodating volume is uniformly deducted. The common portions of each candidate sub-region are merged to form a common injection space, the volume of which is calculated according to the following formula:

[0099] in, The volume of the shared injection space, in units of ; This represents the number of candidate sub-regions. For the first The proportion of votes received by each candidate sub-region; For the first The current remaining capacity of each candidate sub-region, in units of .

[0100] Based on the aforementioned example, the common portions of the three candidate sub-regions are 3276, 1656, and 336, respectively. The volume of the shared injection space is 5268. If the dedicated space of the first grouting borehole is 9100... The dedicated space for the second grouting borehole is 8400. The remaining pore volume is 22768. .

[0101] When calculating in time intervals, source identifiers are added to the grout entering the common injection space from the first and second grouting boreholes. These source identifiers only record the grout source and do not change the flow rate calculation of the grout channel. When two grouting boreholes inject grout into the same common calculation unit at the same time step, the source is allocated according to the volume ratio of the two grout streams entering the common calculation unit; the remaining capacity of the common calculation unit is uniformly deducted once based on the sum of the volumes occupied by the two grout streams. The same updated remaining capacity is read from the subsequent two grouting boreholes.

[0102] For example, a shared computing unit has a remaining capacity of 80 at the start of a time step. The first grouting borehole entered the grout body 20 mm deep. The second grouting borehole entered the grout body 10 The converted particle bulk volumes are 15.4 and 7.7, respectively. Therefore, the updated remaining capacity of this shared computing unit is 56.9. The first and second grouting boreholes accounted for two-thirds and one-third of the total source, respectively, but the total number of borehole groups was only reduced by 23.1%. .

[0103] In step S1303, the volume occupied by the slurry and the expected additional dry gangue mass are calculated based on the corresponding gangue slurry parameters. Before each batch of gangue slurry enters the main pipeline, the slurry density collected by the online densitometer is read, and the solid mass concentration is obtained by sampling and drying. The solid retention rate, true density of gangue particles, and particle porosity after filling are also obtained. The solid retention rate refers to the ratio of the mass of dry gangue remaining in the calculated area of ​​the goaf to the mass of dry gangue at the entrance, obtained through on-site drainage sampling and mass conservation calculation; when there are no on-site drainage conditions, a columnar settling test under the same particle size distribution and hydrochemical conditions is used for calibration. The particle porosity after filling is calculated based on the dry density after stable settling of the test column.

[0104] The conversion factor for converting slurry volume to underground particle accumulation volume is:

[0105] in, Density of the slurry, in units of ; This refers to the solid mass concentration. Solid retention rate; The true density of the gangue particles is given in units of 1000 ppm. ; This refers to the porosity of the particles after filling. This is the conversion factor.

[0106] Within a time step, the first The remaining accommodative volume of each computing unit is updated according to the following formula:

[0107] in, The updated remaining capacity. This represents the remaining usable volume before the update. The volume of slurry entering this calculation unit is expressed in units of... .

[0108] The corresponding mass of retained dry gangue is:

[0109] in, To preserve the quality of dry gangue, the unit is... .

[0110] In one example, the slurry density is 1750. The solid mass concentration was 0.75, the solid retention rate was 0.98, and the true density of the gangue particles was 2600. After filling, the particle packing porosity is 0.36, and the conversion factor is 0.773. 100 [units of something] are injected into a certain computing unit. When dealing with slurry, the remaining usable volume after deduction is 77.3. The remaining dry gangue weight was 128,625 kg. (Regarding 22,768...) Based on the parameters of this batch, the remaining slurry volume that can be accommodated in the borehole group is estimated to be 29455. The estimated additional dry gangue is 37,886 tons.

[0111] In step S1304, the grouting filling volume of the borehole group when the grouting termination condition is met is predicted. The remaining usable volume of the borehole group, the current gangue grout parameters, and the planned grouting flow rate are input into the goaf spatial calculation model. The time step is determined according to the remaining usable volume of the calculation unit and the channel flow rate, ensuring that the particle accumulation volume entering any calculation unit in a single time step does not exceed 5% of the remaining usable volume of that calculation unit at the beginning of the time step. This proportion is determined through a time step convergence test: if the predicted borehole pressure change does not exceed three standard deviations of the pressure sensor reference noise after halving the time step, the original time step is retained; otherwise, it is halved again.

[0112] For example, a computing unit has a remaining capacity of 60. The conversion factor is 0.773, corresponding to a channel flow of 0.02. The requirement is that the particle packing volume in a single time step does not exceed 3. If the time step does not exceed 194s, then 180s is used for calculation. At each time step, the slurry channel flow rate, calculation unit pressure, source ratio, remaining containable volume and retained dry gangue mass are solved sequentially, and then the updated results are passed to the next time step.

[0113] The grouting termination conditions include the termination pressure, termination flow rate, and termination duration obtained from the engineering design documents. The predicted termination time is recorded only when the predicted orifice pressure reaches the termination pressure, the predicted grouting flow rate is lower than the termination flow rate, and the duration reaches the termination duration. In one example, the termination pressure is 2.25 MPa, the termination flow rate is 50 L / min, and the termination duration is 15 min; the model has accumulated an additional grout volume of 29280... The predicted orifice pressure reached 2.25 MPa, but the flow rate remained at 68 L / min. Therefore, the calculation continued until the cumulative additional slurry volume reached 29410. When the flow rate drops to 47 L / min and remains there for 15 minutes, this moment is recorded as the end of the prediction.

[0114] If the predicted orifice pressure reaches the equipment's allowable pressure, but the predicted grouting flow rate has not yet fallen below the end flow rate, the pressure limitation status is recorded, and the cumulative injection volume under the current control scheme is taken as the limitation result. This status is not considered as the goaf being full. The final output includes the expected additional grout volume of the first grouting borehole, the expected additional grout volume of the second grouting borehole, the corresponding expected additional dry gangue mass, the expected additional dry gangue mass of the borehole group, and the expected end time. The expected additional amount for each borehole is obtained by combining the source proportion in the common injection space with the injection volume of its respective dedicated space.

[0115] In some embodiments, the method further includes updating the co-injection ratio and flow resistance when the next disturbance triggering condition is met. The upper and lower limits of the previous co-injection ratio are used to predict the remaining slurry volume of the borehole group, and the ratio of the difference between the two predictions to the average of the two predictions is calculated. When this ratio reaches 5%, the next disturbance triggering condition is met. 5% is taken as the ratio of the minimum adjustable volume of a single batch in the self-made slurry system to the average predicted volume of the borehole group. When engineering equipment changes, this ratio is recalculated based on the actual minimum adjustable volume.

[0116] For example, using the upper limit of the common injection ratio to predict the remaining slurry volume of the borehole group is 31,000. The lower limit of the joint betting ratio is predicted to be 29200. The difference between the two predictions is 1800. The average value is 30100 The ratio is 5.98%, so the aforementioned steps are repeated to perform an equal transfer and obtain a new cross-pressure response.

[0117] The new flow rate sequence and measured subsurface inlet pressure sequence are used to recalculate the co-injection ratio. If the co-injection ratio decreases, the common portion of the corresponding candidate sub-region is reduced; if the response time is prolonged but the change in the co-injection ratio does not exceed the range of the previous round, the co-injection ratio is maintained, and the flow resistance of the corresponding slurry channel is adjusted. The adjustment of the flow resistance is still based on minimizing the objective function between the predicted subsurface inlet pressure and the measured subsurface inlet pressure. The inputs are the new flow rate sequence, the measured subsurface inlet pressure sequence, and the previous round of flow resistance, and the output is the updated flow resistance.

[0118] For example, the flow resistance in a certain slurry channel is 6,000,000. The time for the new round of cross-pressure response has been extended from 85s to 120s, while the co-injection ratio remains within the range of the previous round; the flow resistance is calculated to be 6,500,000, 7,000,000, and 7,500,000 respectively. The corresponding objective functions are 0.0017, 0.0011, and 0.0014, respectively. The value is 7000000. As an updated result.

[0119] The remaining saturated volume deducted before the update remains unchanged, and the updated common injection ratio and flow resistance only participate in subsequent time step calculations. If no new effective cross-pressure response is formed in either direction, first check if the total grouting flow rate is within the allowable deviation range, and check the grout density, valve operation, and sensor records. If the data is normal, use the previous round's common injection ratio as the initial value and recalculate within the range of 0 to the previous round's value. If the upper limit of the recalculated common injection ratio is lower than the identifiable lower limit under the current pressure and noise conditions, update the common injection ratio of the corresponding candidate sub-region to 0; otherwise, retain the recalculated value range. The identifiable lower limit is gradually increased using the goaf spatial calculation model until the predicted cross-pressure response reaches three standard deviations of the pressure sensor's reference noise.

[0120] According to embodiments of this disclosure, field data is collected by a programmable logic controller (PLC), and an industrial computer performs common injection ratio calculation and hole group gangue grouting filling volume prediction after each round of disturbance. For example, when the model contains 10,000 to 50,000 computing units, the industrial computer can employ an 8-core processor and 32GB of memory; pump start-up and shutdown, valve operation, and pressure protection are still controlled by on-site safety interlocks.

[0121] Through the above implementation process, the common injection space of the two grouting boreholes is determined by the cross-pressure response generated by the bidirectional equal transfer. The pressure loss of the main pipeline, branch pipeline, and wellbore, as well as the flow rate change of the grouting borehole itself, are deducted from the borehole pressure sequence. The common injection space is measured only once in the remaining accommodative volume of the borehole group. The actual injection volume is converted into particle packing volume and retained dry gangue mass according to the corresponding gangue slurry parameters. As grouting progresses, the new cross-pressure response continues to update the common injection ratio and the flow resistance of the slurry channel. The deducted remaining accommodative volume is not reversed. Based on this, the gangue grouting filling volume when the two grouting boreholes and the borehole group reach the grouting termination conditions is obtained.

[0122] Figure 5 A block diagram of a goaf grouting and backfilling volume prediction system according to an embodiment of the present disclosure is shown. Figure 5 As shown, the system includes: The spatial model construction module 501 is used to construct a spatial calculation model of the goaf based on the spatial exploration data of the goaf, the borehole trajectory and the current gangue slurry parameters, determine the reachable area of ​​the two grouting boreholes, and divide the intersection of the two reachable areas into candidate sub-regions; The cross-pressure response acquisition module 502 is used to acquire the single-hole reference response of two grouting boreholes when the other grouting borehole is closed, as well as the pressure loss of the main pipeline, branch pipeline, and wellbore; when two grouting boreholes are grouting simultaneously and the total grouting flow rate is within the allowable deviation range, the flow rate reduction of one grouting borehole is transferred equally to the other grouting borehole, and the flow rate sequence and orifice pressure sequence are collected; the orifice pressure sequence is corrected according to the pressure loss and the single-hole reference response to obtain the cross-pressure response; The remaining accommodative volume determination module 503 is used to solve the common injection ratio of each candidate sub-region based on the cross pressure response, determine the common injection space, deduct the remaining accommodative volume of the common injection space according to the actual injection volume and the corresponding gangue slurry parameters, and merge it with the dedicated space of the two grouting boreholes to obtain the remaining accommodative volume of the borehole group. The filling volume prediction module 504 is used to predict the filling volume of gangue grouting in the hole group when the grouting end conditions are met, based on the remaining accommodable volume of the hole group, the current gangue slurry parameters, and the planned grouting flow rate.

[0123] In some embodiments, the system provided in this disclosure may have functions or include modules that can be used to execute the methods described in the above method embodiments. The specific implementation of these methods can be referred to the description in the above method embodiments, and for the sake of brevity, they will not be repeated here.

[0124] Figure 6 A block diagram of an electronic device according to an embodiment of the present disclosure is shown. (Refer to...) Figure 6 Electronic devices can be provided as servers or terminal devices. (See reference...) Figure 6 The electronic device includes a processing component 601, which further includes one or more processors, and memory resources represented by memory 602 for storing instructions, such as application programs, that can be executed by the processing component 601. The application programs stored in memory 602 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 601 is configured to execute instructions to perform the methods described above.

[0125] The electronic device may also include a power supply component 603 configured to perform power management of the electronic device, a wired or wireless network interface 604 configured to connect the electronic device to a network, and an input / output interface 605 (I / O interface). The electronic device can operate on an operating system stored in memory 602.

[0126] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 602 including computer program instructions that can be executed by a processing component 601 of an electronic device to perform the above-described method.

[0127] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for predicting the amount of gangue grouting and backfilling in goaf areas, characterized in that, include: Based on the spatial exploration data of the goaf, the borehole trajectory and the current gangue slurry parameters, a spatial calculation model of the goaf is constructed to determine the reachable areas of the two grouting boreholes, and the intersection of the two reachable areas is divided into candidate sub-regions; The single-hole reference responses of two grouting boreholes are obtained when the other grouting borehole is closed, along with the pressure losses of the main pipeline, branch pipelines, and wellbore. When grouting occurs simultaneously in both boreholes and the total grouting flow rate is within the allowable deviation range, the reduced flow rate from one borehole is transferred equally to the other borehole, and flow rate sequences and orifice pressure sequences are collected. The orifice pressure sequences are corrected based on the pressure losses and the single-hole reference responses to obtain a cross-pressure response. Specifically, this includes deducting the corresponding pressure losses of the main pipeline, branch pipelines, and wellbore from the orifice pressure sequence, and then deducting the underground inlet pressure changes caused by the flow rate changes of the corresponding grouting borehole based on the single-hole reference response. Data segments whose remaining pressure changes continuously exceed three times the standard deviation of the corresponding pressure sensor reference noise for at least two pressure time windows are defined as valid cross-pressure responses. The common injection ratio of each candidate sub-region is determined based on the cross-pressure response to define the common injection space. The determination of the common injection ratio includes: setting a common injection ratio for each candidate sub-region with a value range of zero to one; inputting the flow sequence into the goaf spatial calculation model to calculate the predicted underground inlet pressure of the two grouting boreholes; establishing an objective function based on the normalized deviation between the predicted underground inlet pressure and the measured underground inlet pressure after deducting the pressure loss; and solving for each common injection ratio through bounded iteration. The bounded iteration employs a bounded finite-memory quasi-Newton method, with multiple different initial values. The solution is performed, and the solution with the minimum objective function is selected. The minimum objective function value plus the convergence threshold determined based on pressure noise is used as the upper limit of the acceptable objective function. The upper and lower limits of the common injection ratios are determined from the solution results that satisfy the upper limit of the acceptable objective function. The remaining capacity of the common injection space is uniformly deducted according to the actual injection volume and the corresponding gangue slurry parameters, and merged with the dedicated space of the two grouting boreholes to obtain the remaining capacity of the borehole group. Based on the remaining capacity of the borehole group, the current gangue slurry parameters, and the planned grouting flow rate, the gangue grouting filling volume of the borehole group when the grouting termination condition is reached is predicted.

2. The method according to claim 1, characterized in that, The spatial calculation model of the goaf includes calculation units, slurry channels, and injection nodes. The initial accommodative volume is determined based on the planar area, effective height, and initial porosity of each calculation unit. Slurry channels are established between spatially adjacent calculation units that are not blocked by complete coal pillars, continuous water-resistant layers, or consolidated backfill bodies. The position where the borehole trajectory intersects with the calculation unit after entering the goaf is set as the injection node.

3. The method according to claim 2, characterized in that, The determination of the reachable region includes: starting from the two injection nodes respectively, solving the slurry flow state based on the current flow initiation pressure difference of the gangue slurry, the flow resistance of each slurry channel and the allowable grouting pressure, and forming the reachable region of the corresponding grouting borehole by the calculation units that can be reached by the corresponding injection nodes; dividing the intersection of the two reachable regions into the candidate sub-regions according to spatial continuity, geological properties and slurry channel direction.

4. The method according to claim 3, characterized in that, The acquisition of the pressure loss and the single-hole reference response includes: before the gangue slurry enters the goaf, collecting the pressure loss of the main pipeline, the branch pipeline and the shaft at multiple flow points; sequentially closing one grouting borehole, performing short-term test injection at multiple flow points on another grouting borehole, deducting the corresponding pressure loss, and combining each flow point with the corresponding underground inlet pressure to form the single-hole reference response.

5. The method according to claim 4, characterized in that, The equal transfer includes: after the reference flow rates of the two grouting boreholes stabilize, first reduce the flow rate of one grouting borehole and increase the flow rate of the other grouting borehole by the same amount, restore the reference flow rate, and then perform the reverse equal transfer; the allowable deviation range is determined based on the measurement uncertainty of the two branch flow meters and the main pipeline total flow meter and the fluctuation of the total grouting flow rate in the reference stage.

6. The method according to claim 5, characterized in that, The deduction of the remaining accommodating volume includes: dividing the common part and the non-common part according to the common injection ratio of each candidate sub-region; recording the source of the grout entering the same common part from the two grouting boreholes respectively, and allocating the source ratio according to the entering volume; converting the volume of the grout entering the same common part into the particle packing volume according to the corresponding gangue grout parameters, and deducting the remaining accommodating volume of the common part once.

7. A system for predicting the amount of grout filling in goaf areas, characterized in that, include: The spatial model construction module is used to construct a spatial calculation model of the goaf based on the spatial exploration data of the goaf, the borehole trajectory and the current gangue slurry parameters, determine the reachable area of ​​two grouting boreholes, and divide the intersection of the two reachable areas into candidate sub-regions; The cross-pressure response acquisition module is used to acquire the single-hole reference response of two grouting boreholes when the other grouting borehole is closed, as well as the pressure loss of the main pipeline, branch pipeline, and wellbore. When two grouting boreholes are grouting simultaneously and the total grouting flow rate is within the allowable deviation range, the reduced flow rate of one grouting borehole is transferred equally to the other grouting borehole, and the flow rate sequence and orifice pressure sequence are collected. The orifice pressure sequence is corrected according to the pressure loss and the single-hole reference response to obtain the cross-pressure response. Specifically, this includes deducting the pressure loss of the corresponding main pipeline, branch pipeline, and wellbore from the orifice pressure sequence, and then deducting the underground inlet pressure change caused by the flow rate change of the corresponding grouting borehole based on the single-hole reference response of the corresponding grouting borehole. Data segments in which the obtained residual pressure change continuously exceeds three times the standard deviation of the corresponding pressure sensor reference noise and lasts for no less than two pressure time windows are determined as valid cross-pressure responses. The remaining accommodative volume determination module is used to determine the common injection ratio of each candidate sub-region based on the cross-pressure response, and to determine the common injection space. The determination of the common injection ratio includes: setting a common injection ratio for each candidate sub-region with a value range of zero to one; inputting the flow sequence into the goaf spatial calculation model; calculating the predicted underground inlet pressure of the two grouting boreholes; establishing an objective function based on the normalized deviation between the predicted underground inlet pressure and the measured underground inlet pressure after deducting the pressure loss; and solving for each common injection space through bounded iteration. The bounded iteration employs a bounded finite-memory quasi-Newton method, solving the problem with multiple different initial values ​​and selecting the solution with the smallest objective function. The minimum objective function value plus a convergence threshold determined based on pressure noise is used as the upper limit of the acceptable objective function. The upper and lower limits of each common injection ratio are determined from the solution results that satisfy the upper limit of the acceptable objective function. The remaining accommodative volume of the common injection space is uniformly deducted according to the actual injection volume and the corresponding gangue slurry parameters, and then merged with the dedicated space of the two grouting boreholes to obtain the remaining accommodative volume of the borehole group. The filling volume prediction module is used to predict the filling volume of gangue grouting in the hole group when the grouting end conditions are met, based on the remaining accommodable volume of the hole group, the current gangue slurry parameters, and the planned grouting flow rate.

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