A method for dynamic prediction of surface subsidence in grouting and filling mining
By using the improved Weibull model and probability integral method, combined with grouting and filling mining parameters, the problem of low accuracy in predicting dynamic surface deformation in underground coal mines was solved, achieving more accurate subsidence prediction and engineering guidance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN RES INST OF CHINA COAL TECH & ENG GRP CORP
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-10
AI Technical Summary
Existing technologies have low accuracy in predicting the dynamic surface deformation caused by underground coal mining, making it difficult to provide real-time guidance for surface subsidence, and the impact of grouting and filling activities has not been fully considered.
An improved Weibull model combined with the probability integral method was adopted. By dividing the rectangular working face into multiple mining units, the subsidence of each unit and the time function value of the Weibull model were calculated. Dynamic subsidence prediction was carried out in combination with grouting parameters. The lithological parameters of bedrock and loose layer were considered, and the impact of surface subsidence was described in segments.
It improves the accuracy of dynamic prediction of surface subsidence, enabling more accurate prediction of the extent and degree of surface subsidence basins, and is suitable for practical engineering applications.
Smart Images
Figure CN122365879A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of coal mining subsidence, specifically to a method for dynamically predicting surface subsidence during grouting and filling mining. Background Technology
[0002] The loose layer consists of Quaternary and Neogene strata, composed of soil, sand, gravel, and pebble layers. Its large internal pores and unstable physical properties lead to unique patterns in surface deformation caused by underground coal mining. Overburden isolation grouting technology involves preparing fly ash slurry and injecting it under high pressure into the delamination cavities formed by varying degrees of bending in the overlying strata due to mining operations through surface-drilled grouting boreholes. This controls surface deformation while simultaneously treating fly ash waste, achieving green mining. While surface subsidence due to coal face mining meets the predictions of the probability integral method, the concurrent grouting activity slows the expansion and extent of the subsidence basin. The final outcome of surface subsidence is influenced by both mining and grouting activities; therefore, a combined analysis of mining and grouting parameters is necessary for accurate prediction. The probability integral method is widely used in predicting surface subsidence caused by grouting and filling mining operations and is a relatively mature static analysis method. However, during the mining and grouting activities, it is necessary to dynamically predict and analyze surface subsidence, and to provide real-time guidance for mining and grouting activities based on surface subsidence. Existing methods have the problem of low accuracy in dynamic prediction, making them difficult to apply widely. Summary of the Invention
[0003] To overcome at least one deficiency in the prior art, this application provides a method for dynamically predicting surface subsidence during grouting and filling mining.
[0004] Firstly, a method for dynamically predicting surface subsidence during grouting and backfilling mining is provided, including:
[0005] Divide the rectangular working surface into n One mining unit; The subsidence of each mining unit at any point on the surface is calculated using the probability integral method. Calculate each mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula:
[0006] in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected timeT The time elapsed, The volume of grout injected into the delamination cavity. This refers to the volume of the underground goaf. The product of the subsidence of each mining unit at any surface point and the time function value of the Weibull model is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.
[0007] In one embodiment, the mining unit i From the time the working face advances to the center of the mining unit until the expected time T Time elapsed The following formula is used for calculation:
[0008]
[0009] in, The offset distance to the left turning point. This is the starting torque coefficient. The average mining depth of the rectangular working face. The average Poisson's ratio of the bedrock. When each mining unit is opened, For mining units The time when the harvest was completed, For mining units From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, For mining units i The time when the harvest was completed, This refers to the number of days required to complete the estimated portion of mining operations at the working face.
[0010] In one embodiment, the subsidence of each mining unit at any point on the surface is expressed by the following formula:
[0011]
[0012]
[0013]
[0014] in, For mining units i at any surface point The amount of subsidence at that location, To the coal seam dip angle The final maximum subsidence value at the ground surface point below; To calculate mining units i The tendency is broad. For mining units i The trend is long, Indicates mining unit i The radius of the corresponding surface moving basin, For mining units i Center point coordinates The average thickness of the rectangular working face is [not specified]. To account for the overall subsidence coefficient caused by the thick loose layer; The density of mudstone. For a thick, loose layer, The subsidence coefficient is the result of the improved probability integral method within bedrock. Sub For the delaminated cavity ellipsoid in z The depth of shaft deflection. This represents the maximum deflection value that still occurs in the overlying bedrock strata after the grout injection is completed.
[0015] In one embodiment, the maximum deflection value still generated in the overlying bedrock strata after the grout injection is completed. The following formula is used for calculation:
[0016] in, The cavity volume of the delamination cavity. The volume of grout injected into the delamination cavity. The length of the path is calculated based on the coordinates of the corner points of the rectangular working surface. The height of the water-conducting fracture zone, The average fracture angle of the strata. The dip length is calculated based on the coordinates of the corner points of the rectangular working surface.
[0017] In one embodiment, the mining unit i The radius of the corresponding surface moving basin The following formula is used for calculation:
[0018] in, Indicates the thickness of the loose layer. This represents the average mining depth of the rectangular working face. Average height from the working surface to the delamination cavity The internal friction angle of rock and soil layers in loose geological formations. It represents the average internal friction angle of the rock within the overlying loose bedrock layer.
[0019] Secondly, a device for dynamically predicting surface subsidence during grouting and filling mining is provided, comprising: The work surface division module is used to divide a rectangular work surface into... n One mining unit; The subsidence calculation module is used to calculate the subsidence of each mining unit at any point on the surface using the probability integral method. The Weibull model time function value calculation module is used to calculate the value of each mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula:
[0020] in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, The volume of grout injected into the delamination cavity. The volume of the goaf; The dynamic subsidence value determination module is used to multiply the subsidence of each mining unit at any surface point by the time function value of the Weibull model, which is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.
[0021] Compared with the prior art, this application has the following beneficial effects: 1. The Weibull model with improved parameters is adopted as the theoretical model for the dynamic prediction of surface subsidence caused by grouting and filling mining. This model is the same as the commonly used Knothe time function before the grouting activity begins. After the grouting activity begins, the model basis is more reasonable under the guidance of the idea of segmented description, taking into account the influence of the injection-production ratio parameter on surface subsidence. The accuracy of the dynamic prediction of surface subsidence is higher.
[0022] 2. By utilizing the lithological parameters of the bedrock and loose layers above the grouting and filling mining face, the extent of the surface subsidence basin is derived. Dynamic function parameter calculations using mining and grouting parameters provide clear meanings and eliminate the need for fitting through extensive observations; the results can be directly derived from physical properties. Furthermore, the selection of the internal friction angle within the bedrock and loose layers improves the calculation of the mining movement angle in thick loose layer mining areas, resulting in a more accurate determination of the extent of the surface subsidence basin.
[0023] 3. The model parameters in this application have clear physical meanings, the solution approach is clear and straightforward, there is a rigorous theoretical derivation, and all of them use analytical solutions, which are easy to program and implement, have high execution efficiency, good result accuracy, and have excellent engineering application prospects. Attached Figure Description
[0024] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A flowchart illustrating the dynamic prediction method for surface subsidence during grouting and backfilling mining is shown. Figure 2 A schematic diagram of the division of mining units in the working face is shown; Figure 3 A schematic diagram of the working face establishment method is shown; Figure 4 A schematic diagram of the volume of the delamination cavity is shown; Figure 5 A schematic diagram is shown illustrating the improvement of the surface-moving basin radius based on the internal friction angle between the loose layer and the bedrock. Figure 6 A schematic diagram of the working face's geographical location is shown; Figure 7 This figure shows the predicted two-dimensional result of surface subsidence after 186 days of mining at the 7226 grouting and filling mining face; Figure 8 This figure shows the expected two-dimensional result of surface subsidence after 220 days of mining at the 7226 grouting and filling mining face; Figure 9 This figure shows the expected two-dimensional result of surface subsidence after 247 days of mining at the 7226 grouting and filling mining face; Figure 10 This figure shows the predicted two-dimensional result of surface subsidence after 281 days of mining at the 7226 grouting and filling mining face; Figure 11 This figure shows the predicted two-dimensional result of surface subsidence after 303 days of mining at the 7226 grouting and filling mining face; Figure 12 The figure shows the expected two-dimensional result of surface subsidence after 345 days of mining at the 7226 grouting and filling mining face. Detailed Implementation
[0025] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.
[0026] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution of this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.
[0027] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.
[0028] This application provides a method for dynamically predicting surface subsidence during grouting and backfilling mining. Figure 1 A flowchart illustrating the dynamic prediction method for surface subsidence during grouting and backfilling mining is shown. (See attached diagram) Figure 1 The method mainly includes the following steps: Step S1, divide the rectangular working surface into n One mining unit.
[0029] Here, the length is divided according to the working face unit. l U and the expected working face advance length Determine the number of mining units to be divided into working faces. n . Figure 2 A schematic diagram of the division of mining units in the working face is shown.
[0030] Establish the projected coordinate system: The direction of the coal seam's descent must point towards the vertical axis of the projected coordinate system. y In the negative direction, if the working face advances from left to right, the lower left corner of the working face is taken as the origin of the coordinate system; otherwise, the lower right corner of the working face is taken as the origin of the coordinate system. During the planning process, the working face is adjusted relative to... y Axisymmetry transforms into a projection from left to right. Figure 3 A schematic diagram of the working face establishment method is shown.
[0031] The actual coordinate system is transformed, and the corner points of the working face are sorted clockwise. Then, considering the offset of the working face inflection points and the dip angle of the coal seam, the actual working face range is transformed into the calculated working face range. The coordinate transformation method is as follows:
[0032] In the formula, To predict the coordinates in the coordinate system, The coordinates are in the actual coordinate system. and It is the expected coordinate of the origin o in the actual coordinate system. The angle by which the actual coordinate system is rotated counterclockwise to the expected coordinate system.
[0033] Step S2: Calculate the subsidence of each mining unit at any point on the surface using the probability integral method.
[0034] Specifically, the subsidence of each mining unit at any point on the surface is expressed by the following formula:
[0035]
[0036]
[0037]
[0038] in, For mining units i at any surface point The amount of subsidence at that location, To the coal seam dip angle The final maximum subsidence value at the ground surface point below; To calculate mining units i The tendency is broad. For mining units i The trend is long, Indicates mining unit i The radius of the corresponding surface moving basin, For mining units i Center point coordinates The average thickness of the rectangular working face is [not specified]. To account for the overall subsidence coefficient caused by the thick loose layer; The density of mudstone. For a thick, loose layer, The subsidence coefficient is the result of the improved probability integral method within bedrock. Sub For the delaminated cavity ellipsoid in z The depth of shaft deflection. This represents the maximum deflection value that still occurs in the overlying bedrock strata after the grout injection is completed.
[0039] Here, due to the deflection of the bedrock, the soil particles within the thick loose layer lose water and compress, gradually compacting into mudstone. Therefore, the settlement coefficient is determined using the improved probability integral method within the bedrock. .
[0040] The maximum deflection value still generated in the overlying bedrock strata after the grout injection is completed. The following formula is used for calculation:
[0041] in, The cavity volume of the delamination cavity. The volume of grout injected into the delamination cavity. The length of the path is calculated based on the coordinates of the corner points of the rectangular working surface. The height of the water-conducting fracture zone, The average fracture angle of the strata. The dip length is calculated based on the coordinates of the corner points of the rectangular working surface.
[0042]
[0043] in, The volume of the underground goaf. V HF The volume of rock fragmentation in the water-conducting fracture zone. Sub For the delaminated cavity ellipsoid in z The depth of the shaft's deflection.
[0044] Figure 4 A schematic diagram of the volume of the delamination cavity is shown.
[0045]
[0046]
[0047] Due to the presence of thick Quaternary loose layers, the influence of the loose layer's movement angle on the radius of the surface-moving basin must be considered. When considering both the bedrock boundary angle and the loose layer's movement angle, the radius of the subsided basin needs to be calculated separately and then summed. Mining Unit i The radius of the corresponding surface moving basin The following formula is used for calculation:
[0048] in, Indicates the thickness of the loose layer. This represents the average mining depth of the rectangular working face. Average height from the working surface to the delamination cavity The internal friction angle of rock and soil layers in loose geological formations. It represents the average internal friction angle of the rock within the overlying loose bedrock layer.
[0049] Figure 5 A schematic diagram is shown illustrating the improvement of the surface moving basin radius based on the internal friction angle between the loose layer and the bedrock.
[0050] Step S3: Calculate the mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula:
[0051]
[0052] in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, The volume of grout injected into the delamination cavity. This represents the volume of the goaf.
[0053] This represents the average mining depth of the rectangular working face. Indicates the thickness of the loose layer. This indicates the average unit weight of the bedrock. v This represents the average Poisson's ratio of the bedrock. This represents the average tensile modulus of the bedrock. This represents the average elastic modulus of the bedrock.
[0054] Here, based on the characteristics of grouting and backfilling mining technology and combining mining and grouting parameters, the time function of the Weibull model is improved. Before the grouting and backfilling activity begins... The value equals 0. The improved Weibull model's time function is equivalent to the Knote time function and is used to analyze the dynamic prediction of surface subsidence caused by longwall mining faces. As grouting activities begin, surface subsidence is controlled, and the surface subsidence value decreases.
[0055] Mining Unit i From the time the working face advances to the center of the mining unit until the expected time T Time elapsed The following formula is used for calculation:
[0056]
[0057] in, The offset distance to the left turning point. This is the starting torque coefficient. The average mining depth of the rectangular working face. The average Poisson's ratio of the bedrock. When each mining unit is opened, For mining units The time when the harvest was completed, For mining units From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, For mining units i The time when the harvest was completed, This refers to the number of days required to complete the estimated portion of mining operations at the working face.
[0058] Step S4: The product of the subsidence of each mining unit at any surface point and the time function value of the Weibull model is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.
[0059] In this embodiment, the Weibull model with improved parameters is used as the theoretical model for predicting the dynamics of surface subsidence caused by grouting and filling mining. This model is the same as the commonly used Knothe time function before grouting activities begin; after grouting activities begin, the model basis is more reasonable under the guidance of the idea of segmented description, taking into account the influence of the injection-production ratio parameter on surface subsidence.
[0060] In one embodiment, the 7226 working face of the 82nd mining area of a coal mine is located in the Huaibei mining area of Anhui Province, China. Figure 6 A schematic diagram of the working face's geographical location is shown. Relevant parameters of the working face are shown in Table 1, and parameters predicted by the final state probability integral method are shown in Table 2. Here, we will only use the dynamic prediction of the surface subsidence value across the entire basin as an example for explanation.
[0061] Table 17226 Working Face Parameters
[0062] Table 2 Parameters predicted by probability integral method
[0063] Based on the method described in this application, the surface subsidence values of the 7226 grouting and filling mining face were dynamically predicted after 186 days, 220 days, 247 days, 281 days, 303 days, and 345 days of mining. Figure 7 This image shows the predicted two-dimensional results of surface subsidence after 186 days of mining at the 7226 grouting and filling mining face. Figure 8 This image shows the predicted two-dimensional results of surface subsidence after 220 days of mining at the 7226 grouting and filling mining face. Figure 9 This image shows the predicted two-dimensional results of surface subsidence after 247 days of mining at the 7226 grouting and filling mining face. Figure 10 This image shows the predicted two-dimensional results of surface subsidence after 281 days of mining at the 7226 grouting and filling mining face. Figure 11 This image shows the predicted two-dimensional results of surface subsidence after 303 days of mining at the 7226 grouting and filling mining face. Figure 12A two-dimensional map showing the predicted surface subsidence after 345 days of mining at the 7226 grouting and filling working face is presented. The results show that the method in this application agrees well with the measured values, and the prediction results are highly accurate, meeting the requirements of practical engineering applications.
[0064] Based on the same inventive concept as the method for dynamically predicting surface subsidence during grouting and filling mining, this embodiment also provides a corresponding device for dynamically predicting surface subsidence during grouting and filling mining, including: The work surface division module is used to divide a rectangular work surface into... n One mining unit; The subsidence calculation module is used to calculate the subsidence of each mining unit at any point on the surface using the probability integral method. The Weibull model time function value calculation module is used to calculate the value of each mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula:
[0065] in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, The volume of grout injected into the delamination cavity. The volume of the goaf; The dynamic subsidence value determination module is used to multiply the subsidence of each mining unit at any surface point by the time function value of the Weibull model, which is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.
[0066] The dynamic prediction device for surface subsidence in grouting and filling mining in this embodiment has the same inventive concept as the dynamic prediction method for surface subsidence in grouting and filling mining described above. Therefore, the specific implementation of this device can be found in the embodiment section of the dynamic prediction method for surface subsidence in grouting and filling mining described above, and its technical effects correspond to the technical effects of the above method, so it will not be repeated here.
[0067] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for dynamically predicting surface subsidence during grouting and filling mining, characterized in that, include: Divide the rectangular working surface into n One mining unit; The subsidence of each mining unit at any point on the surface is calculated using the probability integral method. Calculate each mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula: in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, The volume of grout injected into the delamination cavity. This refers to the volume of the underground goaf. The product of the subsidence of each mining unit at any surface point and the time function value of the Weibull model is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.
2. The method as described in claim 1, characterized in that, Mining Unit i From the time the working face advances to the center of the mining unit until the expected time T Time elapsed The following formula is used for calculation: in, The offset distance to the left turning point. This is the starting torque coefficient. The average mining depth of the rectangular working face. The average Poisson's ratio of the bedrock. When each mining unit is opened, For mining units The time when the harvest was completed, For mining units From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, For mining units i The time when the harvest was completed, This refers to the number of days required to complete the estimated portion of mining operations at the working face.
3. The method as described in claim 1, characterized in that, The subsidence of each mining unit at any point on the surface is expressed by the following formula: in, For mining units i at any surface point The amount of subsidence at that location, To the coal seam dip angle The final maximum subsidence value at the ground surface point below; To calculate mining units i The tendency is broad. For mining units i The trend is long, Indicates mining unit i The radius of the corresponding surface moving basin, For mining units i Center point coordinates The average thickness of the rectangular working face is [not specified]. To account for the overall subsidence coefficient caused by the thick loose layer; The density of mudstone. For a thick, loose layer, The subsidence coefficient is the result of the improved probability integral method within bedrock. Sub For the delaminated cavity ellipsoid in z The depth of shaft deflection. This represents the maximum deflection value that still occurs in the overlying bedrock strata after the grout injection is completed.
4. The method as described in claim 3, characterized in that, The maximum deflection value still generated in the overlying bedrock strata after the grout injection is completed. The following formula is used for calculation: in, The cavity volume of the delamination cavity. The volume of grout injected into the delamination cavity. The length of the path is calculated based on the coordinates of the corner points of the rectangular working surface. The height of the water-conducting fracture zone, The average fracture angle of the strata. The dip length is calculated based on the coordinates of the corner points of the rectangular working surface.
5. The method as described in claim 3, characterized in that, Mining Unit i The radius of the corresponding surface moving basin The following formula is used for calculation: in, Indicates the thickness of the loose layer. This represents the average mining depth of the rectangular working face. Average height from the working surface to the delamination cavity The internal friction angle of rock and soil layers in loose geological formations. It represents the average internal friction angle of the rock within the overlying loose bedrock layer.
6. A device for dynamically predicting surface subsidence during grouting and filling mining, characterized in that, include: The work surface division module is used to divide a rectangular work surface into... n One mining unit; The subsidence calculation module is used to calculate the subsidence of each mining unit at any point on the surface using the probability integral method. The Weibull model time function value calculation module is used to calculate the value of each mining unit at a preset time. T The time function value of the Weibull model; the time function value of the Weibull model is calculated using the following formula: in, For mining units i The time function value of the Weibull model. For coefficients, For mining units i From the time the working face advances to the center of the mining unit until the expected time T The time elapsed, The volume of grout injected into the delamination cavity. The volume of the goaf; The dynamic subsidence value determination module is used to multiply the subsidence of each mining unit at any surface point by the time function value of the Weibull model, which is the value of the subsidence of each mining unit at a preset time. T The dynamic subsidence value at any point on the ground surface.