Full-mechanized quick-setting slurry grouting filling and top coal caving control method

Abstract

The present application relates to coal mine filling and water conservation mining technical field, disclose a kind of fully mechanized top coal caving quick-setting slurry grouting filling and top coal caving control method, comprising: collection strata movement data constructs overburden space grid model, calculates strata deformation curvature tensor, through the time variation rate step feature of identifying deflection eigenvalue sequence Capture grouting trigger signal, according to slurry rheological parameter and pipeline feature establish pumping starting time, realize slurry transport and goaf void evolution Time synchronization, and apply discrete pressure pulse at grouting terminal, the technical contradiction of the present application solves filling timing and surrounding rock displacement maladjustment, enhances early support strength of filling body, effectively restricts roof subsidence, and forms dense water-blocking consolidation layer in caving zone, cut off aquifer leakage path, achieve mine water resource protection and safety production.

Description

Technical Field

[0001] This invention relates to the field of coal mine backfilling and water-retaining mining technology, specifically to a method for controlling sedimentation and top coal caving through fully mechanized rapid-setting grouting backfilling. Background Technology

[0002] Currently, in the fully mechanized top-coal caving process of thick coal seams, goaf backfilling technology is a key means to control surface subsidence and protect groundwater resources. By injecting backfilling grout into the caving space behind the working face, a support system is constructed. The space of fragmented and dissipated material formed after the overlying strata fracture and collapse serves as a carrier. The consolidation of the grout and gangue inhibits the continuous delamination and subsidence of the roof strata. However, with the increase of mining depth, the evolution of the goaf media under the high stress of the overlying strata exhibits highly nonlinear characteristics. Existing processes usually start grouting operations after the caving area has basically stabilized. Since the porosity of the collapsed gangue decreases exponentially with the pressure of the overlying strata, the voids in the goaf quickly disappear due to the subsidence of the roof while waiting for the grouting pump to intervene. This passive adaptation to the steady-state environment actually causes the timing of backfilling intervention to be seriously delayed beyond the optimal window for void expansion, resulting in limited grout entry depth and difficulty in forming a load-bearing structure with overall strength.

[0003] To address the problem of excessive filling resistance, conventional improvement schemes often focus on increasing the grouting pump pressure or increasing the density of grouting holes. However, such linear improvement schemes often ignore the dynamic response of heterogeneous rock formations underground. High-pressure environments can easily induce abnormal flow of grout along the support beam, and even cause grout overflow at the coal outlet. Methods that trigger grouting by setting fixed delays or manual experience values ​​cannot adapt to the transient physical process of the goaf transitioning from free collapse to self-locking compression. For example, Chinese invention patent application CN121497416A discloses a grouting method and system for reducing subsidence in pillarless or narrow-pillar mining, which involves deploying a first grouting... The drilling process involves filling the delamination layer and reinforcing the natural accumulation area of ​​the goaf with grouting through reinforcement boreholes. This dual approach reduces settlement. However, this method primarily relies on pre-designed locations or water injection pressure feedback to initiate grouting, neglecting the extremely short physical window during deep fully mechanized mining when collapsed gangue transforms from free sliding to interlocking. Due to a lack of perception of the depth of topological phase change in the overlying strata, the grout filling time lags behind the peak moment of void expansion, causing a sharp increase in the resistance to grout movement within the passive compaction zone. This results in low filling efficiency and difficulty in forming a high-impermeability, water-blocking consolidation layer. Consequently, there is a phase mismatch between the initial setting phase change period of the grout and the closing period of the voids in the goaf in the spatiotemporal dimensions.

[0004] Therefore, how to establish a physical determination mechanism driven by geometric morphological characteristics during the evolution of voids in granular materials, and achieve precise phase coupling between the slurry transport timing and the abrupt change point of void closure rate, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention provides a method for controlling the settling and top coal caving of fully mechanized rapid-setting grout, in order to solve the problems of delayed strength establishment of the filling body and ineffective grout dissipation caused by the mismatch between the existing filling process and the dynamic evolution cycle of the rock strata. The specific technical solution adopted is as follows: This invention proposes a method for controlling the settling and top coal caving of fully mechanized rapid-setting grout, comprising the following steps: Step S101: Collect monitoring data on rock strata movement during the longwall mining process and construct a spatial grid model of the overlying rock in the goaf. Step S102: Based on the displacement vectors of the nodes in the goaf overburden space grid model, calculate the rock stratum deformation curvature tensor at each node location, and extract the deflection principal eigenvalue sequence from the rock stratum deformation curvature tensor. Step S103: Calculate the time change rate of the deflection principal characteristic value sequence. When the absolute value of the time change rate crosses the preset deformation abrupt change threshold, determine that the goaf area has changed from the delamination expansion state to the interlocking closure state, and generate a grouting trigger signal. Step S104: Obtain the initial setting time of the fast-setting grout and the preset pumping parameters, and determine the pumping start time of the fast-setting grout based on the grouting trigger signal to compensate for the travel delay of the fast-setting grout in the grouting pipeline. Step S105: Start the grouting pump at the start of pumping to match the physical time when the fast-setting grout reaches the filling area with the time when the separation space in the goaf reaches its maximum value. Use the squeezing force generated by the rock subsidence to drive the fast-setting grout to diffuse and solidify into the gangue voids. Step S106: During the preset time period at the end of the grouting stage, a discrete pressure pulse sequence with a frequency range of 20kHz to 40kHz is applied to drive the fast-setting grout to penetrate into the micro-cracks of the roof slab and form a water-blocking consolidation layer.

[0006] Preferably, the calculation of the rock layer deformation curvature tensor at each node location in step S102 specifically includes: solving the Hessian matrix of the node location in the overburden spatial grid model of the goaf to characterize the nonlinear deformation characteristics of the local displacement of the overburden.

[0007] Preferably, the judgment logic for determining the transition of the goaf from the delamination expansion state to the interlocking closure state in step S103 follows the following rules: Real-time solution of the characteristic equation of the Hessian matrix: det(H-λI)=0, where H is the Hessian matrix, λ is the principal eigenvalue of the deflection, and I is the identity matrix; Calculation of the second derivative of λ with respect to time t. ,when When the value of the signal undergoes a significant change, the grouting trigger signal is generated.

[0008] Preferably, the generation of the grouting trigger signal in step S103 specifically includes: identifying the evolution process of the rock stratum deformation curvature tensor from overall continuous deformation to local discontinuous abrupt change, mapping the mechanical self-locking moment of the rock stratum structure to the step point of the deflection principal characteristic value sequence, and using it as the control benchmark for executing subsequent grouting actions.

[0009] Preferably, the step S104 of determining the pumping start time specifically includes: calculating the grout delivery time based on the physical length of the grouting pipeline and the preset pumping parameters, and setting the pumping start time based on the weighted value of the grout delivery time and the initial setting time in advance, based on the grouting trigger signal.

[0010] Preferably, in step S105, driving the rapid-setting grout to diffuse and consolidate into the voids of gangue specifically includes: real-time monitoring of the pressure feedback value of the goaf, and dynamically adjusting the output pressure of the grouting pump according to the pressure feedback value, so that the rapid-setting grout generates support resistance through filling and consolidation in the early stage of rock strata activity, thereby limiting the subsidence and displacement of the basic roof strata.

[0011] Preferably, applying a discrete pressure pulse sequence in step S106 specifically includes: using a high-frequency pressure load of 20kHz to 40kHz to destroy the pseudo-dense structure formed by the crushed gangue accumulation, reducing the seepage resistance of the fast-setting grout in the filling area, and improving the filling rate of the grout.

[0012] Preferably, in step S106, a discrete pressure pulse sequence is applied, and its execution parameters are set as follows: the center frequency of the discrete pressure pulse sequence is set to 30kHz, and the transient peak pressure of the pulse is set to 1.2 to 1.5 times the static grouting pressure of the goaf.

[0013] Preferably, the method further includes: using the support top beam displacement sensor to update the boundary displacement conditions of the goaf overburden space grid model in real time, and coupling the filling control logic with the coal release cycle of the fully mechanized mining face in a time sequence.

[0014] Preferably, the formation of the water-blocking consolidation layer in step S106 specifically includes: forming a water-blocking consolidation layer with an anti-seepage pressure of not less than 1.5 MPa by infiltration and cementation of the rapid-setting grout between the rock blocks in the roof collapse zone, thereby cutting off the water-conducting path from the overlying aquifer to the goaf.

[0015] The beneficial effects of this invention are: 1. In the controlled settling of rapid-curing grout injection and filling, the stroke displacement sequence of the hydraulic support tail beam jack is extracted as a dynamic boundary parameter to drive the topological evolution of the three-dimensional geometric mesh model. This achieves an objective mapping of the visible mechanical displacement in the well to the evolution law of the invisible deep space of the goaf. The computing unit solves the Hessian matrix of the surface curvature tensor of the mesh boundary and tracks the transient mathematical singularity of the maximum principal curvature eigenvalue. This captures the geometric phase transition characteristics of the granular medium from the free sliding state to the self-locking extrusion state, eliminates the judgment lag caused by the traditional empirical threshold under heterogeneous collapse conditions, and provides a physically necessary data source for the accurate calibration of the grouting timing.

[0016] 2. The initial setting time of the fast-setting grout, the physical length of the pipeline, and the grout flow rate are integrated into a unified phase control logic to establish the grouting trigger point. This ensures that the physical transport cycle of the grout is synchronized with the extreme expansion cycle of the voids in the goaf. The natural extrusion force generated by the subsidence of the rock strata drives the grout to penetrate and solidify in the gaps between the broken gangue. This precise coordination in the spatiotemporal dimensions enables the filling body to have adaptive bearing capacity in the early stage of violent rock strata activity, increasing the early compressive strength of the filling body by 15% to 22% and effectively restricting the subsidence and displacement of the basic top rock strata.

[0017] 3. During the final residence period of grouting, a discrete pressure pulse sequence in the ultrasonic frequency band is superimposed. The transient pressure difference tears apart the local pseudo-dense structure formed by the gangue accumulation, driving the grout to diffuse into the depth of the micro-fractures. The linkage of various technical actions makes the filling body form a dense water-blocking seal in the junction area, cutting off the water-conducting fracture connection path between the roof aquifer and the goaf. While maintaining the reasonable geometric shape of the top coal release space, the technical goal of protecting the underground aquifer and controlling roof subsidence is achieved. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the core process of grouting and settling control of rapid setting grout in this invention. Figure 2 This is a diagram of the multi-source sensing and logical interaction architecture of the grouting and filling control system of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] A method for controlling the settling and top coal caving of fully mechanized rapid-setting grout, including the following steps: Step S101: Collect monitoring data on rock strata movement during the longwall mining process and construct a spatial grid model of the overlying rock in the goaf. Step S102: Based on the displacement vectors of the nodes in the goaf overburden space grid model, calculate the rock stratum deformation curvature tensor at each node location, and extract the deflection principal eigenvalue sequence from the rock stratum deformation curvature tensor. Step S103: Calculate the time change rate of the deflection principal characteristic value sequence. When the absolute value of the time change rate crosses the preset deformation abrupt change threshold, determine that the goaf area has changed from the delamination expansion state to the interlocking closure state, and generate a grouting trigger signal. Step S104: Obtain the initial setting time of the fast-setting grout and the preset pumping parameters, and determine the pumping start time of the fast-setting grout based on the grouting trigger signal to compensate for the travel delay of the fast-setting grout in the grouting pipeline. Step S105: Start the grouting pump at the start of pumping to match the physical time when the fast-setting grout reaches the filling area with the time when the separation space in the goaf reaches its maximum value. Use the squeezing force generated by the rock subsidence to drive the fast-setting grout to diffuse and solidify into the gangue voids. Step S106: During the preset time period at the end of the grouting stage, a discrete pressure pulse sequence with a frequency range of 20kHz to 40kHz is applied to drive the fast-setting grout to penetrate into the micro-cracks of the roof slab and form a water-blocking consolidation layer.

[0022] Preferably, the calculation of the rock layer deformation curvature tensor at each node location in step S102 specifically includes: solving the Hessian matrix of the node location in the overburden spatial grid model of the goaf to characterize the nonlinear deformation characteristics of the local displacement of the overburden.

[0023] Preferably, the judgment logic for determining the transition of the goaf from the delamination expansion state to the interlocking closure state in step S103 follows the following rules: Real-time solution of the characteristic equation of the Hessian matrix: det(H-λI)=0, where H is the Hessian matrix, λ is the principal eigenvalue of the deflection, and I is the identity matrix; Calculation of the second derivative of λ with respect to time t. ,when When the value of the signal undergoes a significant change, the grouting trigger signal is generated.

[0024] Preferably, the generation of the grouting trigger signal in step S103 specifically includes: identifying the evolution process of the rock stratum deformation curvature tensor from overall continuous deformation to local discontinuous abrupt change, mapping the mechanical self-locking moment of the rock stratum structure to the step point of the deflection principal characteristic value sequence, and using it as the control benchmark for executing subsequent grouting actions.

[0025] Preferably, the step S104 of determining the pumping start time specifically includes: calculating the grout delivery time based on the physical length of the grouting pipeline and the preset pumping parameters, and setting the pumping start time based on the weighted value of the grout delivery time and the initial setting time in advance, based on the grouting trigger signal.

[0026] Preferably, in step S105, driving the rapid-setting grout to diffuse and consolidate into the voids of gangue specifically includes: real-time monitoring of the pressure feedback value of the goaf, and dynamically adjusting the output pressure of the grouting pump according to the pressure feedback value, so that the rapid-setting grout generates support resistance through filling and consolidation in the early stage of rock strata activity, thereby limiting the subsidence and displacement of the basic roof strata.

[0027] Preferably, applying a discrete pressure pulse sequence in step S106 specifically includes: using a high-frequency pressure load of 20kHz to 40kHz to destroy the pseudo-dense structure formed by the crushed gangue accumulation, reducing the seepage resistance of the fast-setting grout in the filling area, and improving the filling rate of the grout.

[0028] Preferably, in step S106, a discrete pressure pulse sequence is applied, and its execution parameters are set as follows: the center frequency of the discrete pressure pulse sequence is set to 30kHz, and the transient peak pressure of the pulse is set to 1.2 to 1.5 times the static grouting pressure of the goaf.

[0029] Preferably, the method further includes: using the support top beam displacement sensor to update the boundary displacement conditions of the goaf overburden space grid model in real time, and coupling the filling control logic with the coal release cycle of the fully mechanized mining face in a time sequence.

[0030] Preferably, the formation of the water-blocking consolidation layer in step S106 specifically includes: forming a water-blocking consolidation layer with an anti-seepage pressure of not less than 1.5 MPa by infiltration and cementation of the rapid-setting grout between the rock blocks in the roof collapse zone, thereby cutting off the water-conducting path from the overlying aquifer to the goaf.

[0031] Example 1: In the longwall mining scenario of a thick coal seam in a high-water-level and ecologically fragile mining area, the falling of top coal induces severe displacement of the overlying strata. The loose rock within the goaf exhibits nonlinear evolution characteristics under the high-strain environment of the overlying strata, and the porosity of the collapsed rock decreases exponentially with the amount of roof subsidence. The loose voids are rapidly eliminated due to the roof rotation and compression. The system utilizes the support top beam displacement sensor to collect real-time monitoring data of strata movement during the longwall mining process. The system uses the stroke displacement sequence of the hydraulic support tail beam jack as a dynamic boundary parameter to drive the topological evolution of the pre-set three-dimensional goaf geometric grid model within the control unit. This converts the visible mechanical displacement underground into the invisible deep spatial evolution law of the goaf, driving the topological evolution of the goaf overlying strata grid model. The computing unit receives the vertical displacement data collected by the support top beam displacement sensor and... A displacement transfer function is introduced, which establishes a physical correlation between the measured points and deep node displacements based on the cantilever beam deflection theory. Attenuation coefficient matrices are set in the model's strike and dip dimensions to allocate boundary displacements at the support to the node coordinates within the grid model. This ensures the strain field distribution reflects the dynamic changes in the invisible overburden delamination space morphology during mining cycles. The goaf overburden space grid model uses the rear caving boundary as a dynamic approximation surface. The computational unit solves for the Hessian matrix H of the node positions in the goaf overburden space grid model, which characterizes the nonlinear deformation features of local overburden displacement. The characteristic equation of the Hessian matrix, det(H-λI)=0, is solved in real-time, where H is the Hessian matrix, λ is the principal eigenvalue of deflection, and I is the identity matrix. The computational unit continuously tracks the time rate of change of the principal eigenvalue sequence of deflection and calculates the second derivative of λ with respect to time t. When detected When the value of the rock stratum undergoes a magnitude jump, the evolution process of the rock stratum deformation curvature tensor from overall continuous deformation to local discontinuous abrupt change is identified. The mechanical self-locking moment of the rock stratum structure is mapped to the step point of the deflection principal characteristic value sequence, and the transformation of the goaf from the delamination expansion state to the interlocking closure state is determined, generating a grouting trigger signal.

[0032] Obtain the initial setting time of the fast-setting slurry Based on the preset pumping parameters and the grouting trigger signal, the pumping start time of the fast-setting grout is determined. This is used to compensate for the travel time delay of the fast-setting grout in the grouting pipeline, according to the formula... Determine the grouting trigger point, where, The absolute time coordinate for the start-up of the grouting pump. The cutoff moment for the void compression state. The physical length of the pipeline from the grouting pump to the junction area of ​​the granular materials. The absolute flow velocity of the slurry within the pipeline. To test the initial setting time of the fast-setting grout at the current ambient temperature, the system was in... The grouting pump is activated continuously to match the physical arrival time of the fast-setting grout in the filling area with the maximum value of the goaf separation space. The compressive force generated by the rock subsidence drives the fast-setting grout to diffuse and solidify into the voids of the gangue. During the preset duration at the end of the grouting stage, a discrete pressure pulse sequence with a frequency range of 20kHz to 40kHz is applied. This high-frequency pressure load disrupts the pseudo-dense structure created by the accumulation of broken gangue, reducing the seepage resistance of the fast-setting grout in the filling area and increasing the grout filling rate. The center frequency of the discrete pressure pulse sequence is set to 30kHz, and the transient peak pressure of the pulse is set to 1.2 to 1.5 times the static grouting pressure of the goaf. This is achieved through the permeation of the fast-setting grout between the rock blocks in the roof collapse zone. The cementation process creates a water-blocking consolidation layer with an anti-seepage pressure of not less than 1.5 MPa, cutting off the water-conducting path from the overlying aquifer to the goaf. While maintaining the geometric shape of the top coal release space, it achieves the effect of protecting the underground aquifer and controlling roof subsidence. A discrete pressure pulse sequence is applied, and a high-frequency electromagnetic vibration valve group is installed at the end of the grouting pipeline. This valve group is controlled by a high-frequency drive circuit to generate pressure fluctuations in the range of 20 kHz to 40 kHz. Before grouting, the parameters are calibrated, and the duty cycle of the drive current pulse is adjusted so that the transient peak pressure fed back by the pressure monitoring unit reaches 1.2 to 1.5 times the static grouting pressure of the goaf. The high-frequency mechanical shearing action is used to destroy the local self-locking structure of the gangue accumulation and increase the diffusion range of the fast-setting grout in the micro-cracks of the roof.

[0033] Example 2: This example verifies the grouting triggering accuracy and water-blocking efficiency of the consolidation layer during the working face advancement process. A 1:50 scale physical similarity simulation test rig was used to simulate the fully mechanized mining conditions of a thick coal seam. This test rig included a three-dimensional loading frame, a hydraulic support scale model, and an overlying strata settlement monitoring system. Data acquisition used a displacement sensor with a measurement resolution of 0.01 mm, and its sampling frequency was set to 100 Hz. A 50 Hz power frequency interference signal was actively superimposed on the test environment, and background vibration noise with a signal-to-noise ratio of 20 dB was introduced to determine the sampling frequency. Factors include the rate of change of the strata deformation curvature tensor. The technical trade-off lies in balancing the ability to capture abrupt changes in strata signals with the computational load of the control unit. Based on the Nyquist sampling theorem and the dynamic characteristics of overburden deformation, the sampling frequency is set to 5Hz to 15Hz for the deformation fluctuation frequency induced by top coal caving. The frequency was set to 100Hz to meet the requirements for collecting changes in the eigenvalue sequence of the Hessian matrix. The experiment was divided into a control group and an invention group. The control group used a static time-series grouting method based on a fixed step size, while the invention group used a spatial grid model of the overlying rock in the goaf and a grouting trigger signal generation method. Three sets of roof subsidence rate gradients were set: a low-intensity gradient of 5.2 mm / h, a medium-intensity gradient of 14.8 mm / h, and a high-intensity gradient of 30.3 mm / h. The original displacement data, including 50Hz power frequency interference, showed spiky fluctuations in the time-domain curve, and the directly calculated second derivative produced a large number of pseudo-step points. The invention group solved the deflection principal eigenvalue sequence λ of the Hessian matrix and used the high-dimensional clustering characteristics of the eigenvalues ​​with respect to the local deformation field to suppress background noise. Under the gradient of 30.3 mm / h, the second derivative of the deflection principal eigenvalue λ with respect to time t... At 12.42s, the signal instantaneously jumped from 0.12 to 0.31 in the normal fluctuation range to 4.65. The physical time deviation between the trigger signal issuance time and the peak value of the goaf separation space was 0.14s. In contrast, the deviation between the grouting start time and the filling window of the comparison sample group reached 2.62s.

[0034] Regarding the discrete pressure pulse frequency at the grouting end, when the pulse frequency is in the range of 20kHz to 40kHz, the grout penetration depth in the filling zone exhibits a non-linear increase with increasing frequency. When the frequency is set to 30kHz and the transient peak pressure of the pulse is set to 1.35 times the static grouting pressure of the goaf, the grout filling rate of the gangue micro-voids reaches 92.83%. When the frequency exceeds the upper limit of 45kHz, the growth slope of the grout filling rate tends to flatten, and the system reaction sites are close to saturation. The test endpoint is determined based on the impermeability strength of the consolidation layer. The water-blocking consolidation layer formed by the sample group of this invention reached an impermeability pressure of 1.62MPa measured in the laboratory. When the pressure load exceeds 1.83MPa, the micro-cracks inside the consolidation layer expand, and the impermeability performance begins to decline. By analyzing the grouting start time... The calibration and application of discrete pressure pulses at the end of the grouting stage form a stable filling body in the dynamically changing goaf environment, blocking the seepage path of the simulated aquifer.

[0035] Example 3: In a deep coal seam fully mechanized longwall face with a mining depth exceeding 800m and significant pressure from the overlying aquifer, the intense mine pressure causes discrepancies in the roof subsidence rate and the goaf closure characteristics. Before formally executing grouting operations, the system enters an initial state definition procedure. Displacement monitoring stations located at the starting point of the longwall mining operation acquire rock strata movement monitoring data during a 50m longwall mining process. The calculation unit generates a deflection principal characteristic value sequence from this data segment. A first-order central difference operation is performed, and the maximum value of the absolute value of the difference is extracted as the initial criterion under the geological conditions. 1.5 times the maximum value is determined as the deformation abrupt change threshold, thereby providing a quantitative benchmark for identifying the transformation of the goaf from the delamination expansion state to the interlocking closure state in the subsequent real-time monitoring stage.

[0036] Determine the start time of pumping the rapid-setting slurry. During the process, to correct for transport time delay errors caused by grouting pump wear or changes in pipeline inner wall roughness, the system executes a grouting pipeline parameter calibration procedure. A flow monitoring unit is installed at the outlet end of the grouting pipeline to measure the instantaneous flow rate of the fast-setting grout under the rated pumping pressure and convert it into the absolute flow velocity within the pipeline. Substitute the measured flow velocity into the formula The operation is performed in the middle, where, The absolute time coordinate for the start-up of the grouting pump. The cutoff moment for the void compression state. The physical length of the pipeline from the grouting pump to the junction area of ​​the granular materials. The absolute flow velocity of the slurry within the pipeline. To test the initial setting time of fast-setting grout at the current ambient temperature, this calibration procedure controls the synchronization difference between the physical time of the grout reaching the filling area and the peak time of the goaf separation space within 0.2s.

[0037] For the discrete pressure pulse sequence application procedure at the end of the grouting stage, the system determines the intervention point of the pressure pulse based on the real-time monitoring feedback of the grouting pump outlet pressure. When the grouting pressure reaches 0.95 times the static equilibrium pressure of the goaf, a pulse generation unit with a center frequency of 30kHz is activated, and the duration is set within the range of 120s to 180s. By applying a discrete pressure pulse sequence with a transient peak pressure of 1.4 times the static grouting pressure within this specific duration, the pseudo-compacted points between gangues undergo displacement and reorganization under the micro-vibration induced by sound waves, causing the average permeability radius of the grout in the filling area to expand from 1.2m to 2.5m. Finally, the anti-seepage pressure of the water-blocking consolidation layer is measured to be stable at 1.75MPa, effectively blocking the permeability channel from the overlying aquifer to the goaf, and achieving a state of coordinated control between underground water-conserving mining and roof subsidence.

[0038] Example 4: Before deploying the filling system at the working face, the setting law of the rapid-setting slurry was calibrated in the laboratory. A temperature-controlled water bath system was used to simulate the ambient temperature of 20°C to 45°C downhole. The viscosity evolution process of the slurry after mixing was monitored by a rotational viscometer. The time it took for the slurry viscosity to increase from the initial flow dynamics to 10 Pa·s was determined as the initial setting time. To investigate the setting behavior of main ingredients and accelerators under different ratio gradients, a feature matrix containing the correspondence between temperature, ratio, and initial setting time was established. The calculation unit calculates the slurry temperature based on data collected by field sensors. Given the current grouting mix ratio, a matrix is ​​retrieved using a bilinear interpolation algorithm. And calculate The value is selected to eliminate the impact of feed temperature fluctuations on the grouting start time. The resulting deviation; after the grouting pump unit is connected to the goaf filling pipeline, the control unit performs the initial pressure benchmark calibration of the filling area, uses the grouting pump to output a small flow rate fluid load, and collects the pressure sequence fed back by the pressure monitoring unit in real time. The stable pressure value when the pressure reading jumps from the pipeline circulation pressure to the goaf resistance equilibrium point is extracted and determined as the static equilibrium pressure of the goaf. The control unit determines the amplitude boundary of the discrete pressure pulse sequence based on the measured reference value, and sets the transient peak pressure of the pulse as... This ensures that the pulse oscillation energy at the end of the grouting stage is within the pressure range required for gangue structure rearrangement, thereby improving the density of the water-blocking consolidation layer.

[0039] In a fully mechanized longwall mining face scenario where mining pressure is evident and the roof structure exhibits a non-uniform distribution, the spatial discrete density of nodes in the goaf overburden spatial grid model affects the fidelity of the curvature tensor solution due to the multiple layers of soft and hard interaction characteristics in the overlying strata. The system executes a model resolution calibration procedure, using pre-set displacement reference stations within the working face roadway to collect the dynamic subsidence displacement of the roof within a period of 0.8m to 1.2m. The spatial step distance Δd between adjacent measuring points is set to 500mm to ensure accurate Hessian matrix calculation. The discretized differential operation of H captures local crack displacements with a scale of not less than 1m. The calculation unit extracts the deflection principal characteristic value sequence within the test area based on the overlying strata spatial grid model of the goaf. When determining the quantitative basis for the deformation abrupt change threshold and eliminating sensor random drift interference, the system implements a background noise calibration procedure before grouting. When the roof is in a non-abrupt subsidence stage, the calculation unit collects a λ sample sequence within 50 sampling periods and calculates the arithmetic mean μ and standard deviation σ of its first-order time change rate based on the sequence. The deformation abrupt change threshold is then determined. Set as With three times The sum, generated by real-time monitoring Absolute value greater than At that time, the judgment system captures the signal generated by the topological evolution of the rock strata. The numerical judgment logic takes the environmental background fluctuation as the feedback benchmark, so that the grouting trigger signal is adapted to the change of geological intensity, so that when the fast-setting grout reaches the filling area, the delamination space of the goaf is in the maximum range, maintaining the overall stability of the mechanical structure of the overlying rock strata.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the settling and top coal venting of rapidly setting grout using fully mechanized coal grouting, characterized in that... Includes the following steps: Step S101: Collect monitoring data on rock strata movement during the longwall mining process and construct a spatial grid model of the overlying rock in the goaf. Step S102: Based on the displacement vectors of the nodes in the goaf overburden space grid model, calculate the rock stratum deformation curvature tensor at each node location, and extract the deflection principal eigenvalue sequence from the rock stratum deformation curvature tensor. Step S103: Calculate the time change rate of the deflection principal characteristic value sequence. When the absolute value of the time change rate crosses the preset deformation abrupt change threshold, determine that the goaf area has changed from the delamination expansion state to the interlocking closure state, and generate a grouting trigger signal. Step S104: Obtain the initial setting time of the fast-setting grout and the preset pumping parameters, and determine the pumping start time of the fast-setting grout based on the grouting trigger signal to compensate for the travel delay of the fast-setting grout in the grouting pipeline. Step S105: Start the grouting pump at the start of pumping to match the physical time when the fast-setting grout reaches the filling area with the time when the separation space in the goaf reaches its maximum value. Use the squeezing force generated by the rock subsidence to drive the fast-setting grout to diffuse and solidify into the gangue voids. Step S106: During the preset time period at the end of the grouting stage, a discrete pressure pulse sequence with a frequency range of 20kHz to 40kHz is applied to drive the fast-setting grout to penetrate into the micro-cracks of the roof slab and form a water-blocking consolidation layer.

2. The method for controlling sedimentation and top coal caving through grouting and filling with rapid-setting slurry according to claim 1, characterized in that, Step S102 calculates the rock strata deformation curvature tensor at each node location, which specifically includes: solving the Hessian matrix of the node location in the overburden spatial grid model of the goaf to characterize the nonlinear deformation characteristics of the local displacement of the overburden.

3. The method for controlling sedimentation and top coal caving through rapid-setting grouting and filling, and controlling the caving of top coal, according to claim 2, is characterized in that... In step S103, the logic for determining the transition of the goaf from the delamination expansion state to the interlocking closure state follows the following rules: Real-time solution of the characteristic equation of the Hessian matrix: det(H-λI)=0, where H is the Hessian matrix, λ is the principal eigenvalue of the deflection, and I is the identity matrix; Calculation of the second derivative of λ with respect to time t. ,when When the value of the signal undergoes a significant change, the grouting trigger signal is generated.

4. The method for controlling sedimentation and top coal caving through grouting and filling with rapid-setting slurry according to claim 1, characterized in that, In step S103, a grouting trigger signal is generated, which specifically includes: identifying the evolution process of the rock stratum deformation curvature tensor from overall continuous deformation to local discontinuous abrupt change, mapping the mechanical self-locking moment of the rock stratum structure to the step point of the deflection principal characteristic value sequence, and using it as the control reference for executing subsequent grouting actions.

5. A method for controlling settling and top coal caving using rapid-setting grouting filling according to claim 1, characterized in that, The step S104 establishes the pumping start time, which specifically includes: calculating the grout delivery time based on the physical length of the grouting pipeline and the preset pumping parameters, and setting the pumping start time based on the weighted value of the grout delivery time and the initial setting time in advance, based on the grouting trigger signal.

6. A method for controlling settling and top coal caving using rapid-setting grouting filling according to claim 1, characterized in that, In step S105, the rapid-setting grout is driven to diffuse and consolidate into the voids of the gangue. Specifically, this includes: real-time monitoring of the pressure feedback value of the goaf, and dynamic adjustment of the output pressure of the grouting pump according to the pressure feedback value, so that the rapid-setting grout generates support resistance through filling and consolidation in the early stage of rock strata activity, thereby limiting the subsidence and displacement of the basic roof strata.

7. A method for controlling sedimentation and top coal caving through rapid-setting grouting and filling, and controlling the caving of top coal, according to claim 1, characterized in that... Step S106 involves applying a discrete pressure pulse sequence, specifically including: using a high-frequency pressure load of 20kHz to 40kHz to destroy the pseudo-dense structure formed by the crushed gangue accumulation, reducing the seepage resistance of the fast-setting grout in the filling area, and increasing the filling rate of the grout.

8. A method for controlling settling and top coal caving using rapid-setting grouting filling according to claim 7, characterized in that, In step S106, a discrete pressure pulse sequence is applied, and its execution parameters are set as follows: the center frequency of the discrete pressure pulse sequence is set to 30kHz, and the transient peak pressure of the pulse is set to 1.2 to 1.5 times the static grouting pressure of the goaf.

9. A method for controlling settling and top coal caving using rapid-setting grouting filling according to claim 1, characterized in that, The method also includes: using the support top beam displacement sensor to update the boundary displacement conditions of the goaf overburden space grid model in real time, and coupling the filling control logic with the coal release cycle of the fully mechanized mining face in a time sequence.

10. A method for controlling sedimentation and top coal caving through grouting and filling with rapid-setting slurry according to claim 1, characterized in that, In step S106, a water-blocking consolidation layer is formed, which specifically includes: through the infiltration and cementation of the rapid-setting grout between the rock blocks in the roof collapse zone, a water-blocking consolidation layer with an anti-seepage pressure of not less than 1.5 MPa is formed, cutting off the water-conducting path from the overlying aquifer to the goaf.

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