Coal mining method with water conservation based on mining-induced fracture grouting of sandstone roof of coal seam

Abstract

The application provides a coal seam sandstone roof mining and treating water mining method based on mining fissure grouting, which comprises the following steps: obtaining hydrogeological parameters of a target working face of a coal mine; determining a roof breaking step distance of the target working face according to the hydrogeological parameters, determining stratum distribution characteristics above the target working face, and determining simulated development characteristics of a water flowing fractured zone of the target working face; determining a grouting layer position according to the simulated development characteristics of the water flowing fractured zone and the stratum distribution characteristics; performing mining on the target working face, and after the distance of the mining reaches the roof breaking step distance each time, performing layered grouting on the grouting layer position corresponding to the target working face in the roof breaking step distance after the roof of the target working face is broken, until the mining of the target working face is completed, and the layered grouting of the grouting layer position corresponding to the target working face is completed, and then the operation is ended. The coal seam sandstone roof mining and treating water mining method based on mining fissure grouting has high safety, high water control mining efficiency and resource saving.

Description

Technical Field

[0001] This application relates to the field of coal mine management technology, and in particular to a method for water-conserving coal mining based on mining-induced fracture grouting for the sandstone roof of coal seams during mining. Background Technology

[0002] Coal mining is a high-intensity production activity that causes significant movement and damage to the overlying strata. Depending on the geological and mining conditions, dynamic "saddle-shaped" caving zones, fracture zones, and overall movement zones gradually form within the overlying strata to varying degrees. When one or more aquifers with high water-bearing capacity exist in the overlying strata, mining-induced fractures can create hydraulic connections between these aquifers within their extended range, transforming them into directly water-bearing aquifers for the mine. The water from these aquifers will flow into the mined-out area along the water-conducting fracture channels. The more fracture channels connecting the aquifers and the higher the water-bearing capacity of the aquifers, the greater the water inflow underground. In severe cases, this can trigger roof water hazards, endangering the safe and efficient production of the mine.

[0003] Currently, grouting is the most common technical method for maintaining aquifer stability and ensuring coal mining safety. However, existing grouting methods typically involve sealing the coal face after mining is completed. This increases the probability of surface subsidence and water seepage, and also increases the difficulty and cost of grouting. Some technologies perform grouting simultaneously with mining, which improves safety, but the continuous damage to the strata during mining leads to a significant increase in grout volume and reduced grouting effectiveness. Therefore, there is an urgent need for a safer, more efficient, and resource-saving water-conserving coal mining method. Summary of the Invention

[0004] In view of this, the purpose of this application is to propose a method for water-conserving coal mining based on mining-induced fracture grouting in the sandstone roof of coal seams to solve the above-mentioned technical problems.

[0005] This application provides a method for water-conserving coal mining based on mining-induced fracture grouting for the sandstone roof of a coal seam, comprising: acquiring hydrogeological parameters of the target working face of the coal mine; determining the roof fracture step distance of the target working face, determining the stratigraphic distribution characteristics above the target working face, and determining the simulated development characteristics of the water-conducting fracture zone of the target working face based on the simulated development characteristics of the water-conducting fracture zone and the stratigraphic distribution characteristics; mining the target working face, and after the roof of the target working face fractures at each mining distance reaching the roof fracture step distance, performing layered grouting on the grouting layer corresponding to the target working face within the roof fracture step distance, until the target working face is completely mined and all the grouting layers corresponding to the target working face are completely grouted, and then ending the operation.

[0006] Further, determining the grouting layer based on the simulated development characteristics of the water-conducting fracture zone and the stratigraphic distribution characteristics includes: determining the maximum development range of the water-conducting fracture zone based on the simulated development characteristics of the water-conducting fracture zone; and selecting the topmost aquitard located within the maximum development range of the water-conducting fracture zone as the grouting layer based on the stratigraphic distribution characteristics.

[0007] Further, the layered grouting includes performing lower layer grouting, middle layer grouting, and upper layer grouting sequentially from bottom to top in the grouting layer; the lower layer grouting involves grouting the lower layer within the grouting layer to create a base, and the grouting material for the lower layer grouting is a fast-setting two-component grout, with a grouting end pressure of 0.8 MPa to 2 MPa; the middle layer grouting involves grouting the middle layer within the grouting layer to fill it, and the grouting material for the middle layer grouting is fly ash cement grout, with a grouting end pressure of 2 MPa to 5 MPa; the upper layer grouting involves grouting the upper layer within the grouting layer to seal it, and the grouting material for the upper layer grouting is clay cement grout, with a grouting end pressure of 2 MPa to 5 MPa.

[0008] Furthermore, the top plate breaking step distance includes the initial pressure step distance. and period to reduce step size ,in, , , The tensile strength of the basic top rock layer, The thickness of the basic top rock layer, This represents the uniformly distributed load of the overlying rock layer on the basic top rock layer.

[0009] Furthermore, the step of performing layered grouting on the grouting layer corresponding to the target working face within the roof breaking step distance after the roof breaking step distance is reached each time the mining distance is reached includes: performing layered grouting on the grouting layer corresponding to the target working face within the initial pressing step distance after the roof breaking step distance is reached for the first time after the mining distance is reached for the first time after the roof breaking step ...

[0010] Further, the step of determining the grouting layer based on the simulated development characteristics of the water-conducting fracture zone and the formation distribution characteristics includes: determining the grouting hole based on the simulated development characteristics of the water-conducting fracture zone; the step of mining the target working face includes: obtaining the test Lvrong value through the grouting hole by conducting a water pressure test; when the test Lvrong value is greater than or equal to the preset Lvrong value, performing auxiliary grouting on the grouting layer.

[0011] Furthermore, the grouting material for the auxiliary grouting is gangue-fly ash slurry, and the grouting end pressure is 4MPa to 5MPa; the preset Lv value is 5Lu.

[0012] Furthermore, the step of performing layered grouting on the grouting layer corresponding to the target working face within the roof breaking step distance after the roof breaking step distance is reached each time the mining distance is reached, includes: monitoring the surface movement of the target working face to obtain the surface subsidence difference value within a preset time; and performing layered grouting on the grouting layer corresponding to the target working face within the roof breaking step distance after the roof breaking step distance is reached each time the mining distance is reached, the roof breaking step distance is reached, and the surface subsidence difference value is less than or equal to the preset subsidence difference value.

[0013] Furthermore, the preset time is one week, and the preset subsidence difference is 30mm.

[0014] Further, the step of mining the target working face includes: obtaining test results by performing borehole television testing or fiber optic sensor testing through the grouting holes; and verifying the results of water pressure tests or surface movement monitoring based on the test results.

[0015] As can be seen from the above, this application provides a method for water-conserving coal mining based on mining-induced fracture grouting for the sandstone roof of a coal seam, comprising: obtaining the hydrogeological parameters of the target working face of the coal mine; determining the roof fracture step distance of the target working face based on the hydrogeological parameters, determining the stratum distribution characteristics above the target working face, and determining the simulated development characteristics of the water-conducting fracture zone of the target working face; determining the grouting layer based on the simulated development characteristics of the water-conducting fracture zone and the stratum distribution characteristics; mining the target working face, and after the roof of the target working face fractures at each mining distance, performing layered grouting on the grouting layer corresponding to the target working face within the roof fracture step distance, until the target working face is completely mined and all grouting layers corresponding to the target working face are completed, and then the operation ends. By obtaining the roof fracture step distance and grouting layer, a foundation is provided for subsequent layered grouting. After the start of mining, grouting is performed layer by layer at the corresponding grouting layer after each roof fracture step distance is reached. This allows for rapid sealing of fractures, good stability, and low cost. Layered grouting balances grouting efficiency, grouting effect, and grouting cost. During the layered grouting process, the target working face can continue mining, enabling "mining and treatment simultaneously" and "mining and treatment cycle," greatly improving mining and treatment efficiency and ensuring safety. This method of water-conserving coal mining based on mining-induced fracture grouting for sandstone roofs is simple, convenient, highly safe, highly efficient in water-controlled mining, resource-saving, and low-cost. By proactively preventing water inrush accidents, it significantly reduces the risk of water seepage, ensuring the safety of personnel and equipment. At the same time, it can effectively reduce the uncontrolled loss of groundwater, reduce mine drainage costs, and protect the regional water resource balance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the process of the coal seam sandstone roof water-conserving mining method based on mining-induced fracture grouting in the embodiments of this application;

[0018] Figure 2 This is a schematic diagram illustrating the first layered grouting operation in an embodiment of this application.

[0019] Figure 3 This is a schematic diagram illustrating the operation of the second layered grouting in an embodiment of this application;

[0020] Figure 4 This is a schematic diagram illustrating the operation of the third layer grouting in an embodiment of this application;

[0021] Figure 5 This is a schematic diagram illustrating the specific operation of each layer of grouting in an embodiment of this application;

[0022] Figure 6 This is a schematic diagram of the observation layout of the target working surface in an embodiment of this application;

[0023] Figure 7 This is a test diagram of the subsidence depth of the observation point of the target working face in an embodiment of this application.

[0024] Attached reference numerals: 1. Target working face; 2. Water-conducting fracture zone; 3. Grouting layer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0026] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] The following describes specific embodiments in conjunction with... Figures 1 to 7 The technical solution of this application will be described in detail below.

[0028] Some embodiments of this application provide a method for water-conserving coal mining based on mining-induced fracture grouting in the sandstone roof of a coal seam, such as... Figure 1 As shown, the process includes the following steps: S1, obtaining the hydrogeological parameters of the target working face of the coal mine.

[0029] The target working face is the location of the coal seam to be mined. Hydrogeological parameters of the target working face can be obtained through field exploration or historical hydrogeological data of the coal mine location. These parameters may include some production geological conditions, such as the lithology, thickness, depth, tensile strength, and uniformly distributed load on the roof strata; they may also include some hydrological conditions, such as the thickness, depth, and structure of aquifers and impermeable layers, without specific limitations.

[0030] S2. Determine the top plate fracture step distance of the target working face based on the hydrogeological parameters, determine the stratigraphic distribution characteristics above the target working face, and determine the simulated development characteristics of the water-conducting fracture zone of the target working face.

[0031] The target working face of the coal seam is topped by a sandstone roof. The roof fracture step distance refers to the step distance at which the roof fractures during mining. To determine the roof fracture step distance, similar coal mines can be identified based on their hydrogeological parameters. The roof fracture step distance of these other mines can be used as the approximate value for this mine. For example, if the geological conditions of the roof and floor lithology, thickness, burial depth, and geological structures (such as faults and folds) are highly consistent, and the mining processes such as mining height, advance speed, and support methods are similar, an approximate value for the roof fracture step distance can be obtained. Alternatively, the roof fracture step distance can be calculated based on the hydrogeological parameters of this coal mine.

[0032] Based on hydrogeological parameters, the stratigraphic distribution characteristics above the target working face can be determined, such as the distribution characteristics of the aquifer and water-bearing layer above the target working face.

[0033] Numerical simulations can be performed based on hydrogeological parameters to obtain the simulated development characteristics of water-conducting fracture zones. For example, hydrogeological parameters and mining process parameters can be input into the simulation software flac3D to simulate the mining process and obtain the simulated development characteristics of water-conducting fracture zones, such as the development height and lateral development range of the water-conducting fracture zones.

[0034] S3. Determine the grouting layer location based on the simulated development characteristics of the water-conducting fracture zone and the formation distribution characteristics.

[0035] During coal seam mining, fractures will form in the roof. These fractures need to be sealed by grouting. Before grouting, the grouting layer needs to be determined. The maximum development range of the water-conducting fracture zone is determined based on the simulated development characteristics of the water-conducting fracture zone. Based on the stratigraphic distribution characteristics, the topmost aquitard located within the maximum development range of the water-conducting fracture zone is selected as the grouting layer.

[0036] S4. The target working face is back-mined. Each time the back-mining distance reaches the roof breaking step distance, after the roof of the target working face is broken, the grouting layer corresponding to the target working face within the roof breaking step distance is grouted in layers until the target working face is completely back-mined and the grouting layer corresponding to the target working face is completely grouted in layers, and then the operation ends.

[0037] As the target working face advances, the roof will periodically fracture; that is, each time the mining distance reaches the roof fracture step distance, the roof of the target working face will fracture. Figures 2 to 4 As shown, after each fracture stabilizes, grouting is performed in layers at the grouting layers corresponding to the target working faces within the fracture step distance of that roof section. During grouting, mining can continue without affecting the mining progress. Layered grouting is repeated until all grouting layers corresponding to the target working faces within the fracture step distance of all roof sections have been grouted, at which point the operation can be terminated. This model transforms traditional passive emergency response into proactive prevention and control, aligning with the concept of green mining. By reducing water hazards and ecological damage, it promotes sustainable development, ultimately achieving the synergistic goals of safe and efficient mining, resource conservation, and environmental protection.

[0038] The segmented grouting operation corresponding to the roof fracture step distance can greatly improve the grouting effect and reduce the grouting cost compared to grouting operations that are carried out continuously with mining. This is because if mining and grouting are carried out simultaneously at the same mining distance, the roof structure is not stable, which will consume a large amount of grouting material. Moreover, the water-conducting fissures that have been grouted and sealed in the previous stage will be severely damaged with subsequent mining, reducing the grouting effect and further increasing the amount of grouting material used.

[0039] By obtaining the roof fracture step distance and grouting layer, a foundation is provided for subsequent layered grouting. After the start of mining, grouting is performed layer by layer at the corresponding grouting layer after each roof fracture step distance is reached. This allows for rapid sealing of fractures, good stability, and low cost. Layered grouting balances grouting efficiency, grouting effect, and grouting cost. During the layered grouting process, the target working face can continue mining, enabling "mining and treatment simultaneously" and "mining and treatment cycle," greatly improving mining and treatment efficiency and ensuring safety. This method of water-conserving coal mining based on mining-induced fracture grouting for sandstone roofs is simple, convenient, highly safe, highly efficient in water-controlled mining, resource-saving, and low-cost. By proactively preventing water inrush accidents, it significantly reduces the risk of water seepage, ensuring the safety of personnel and equipment. At the same time, it can effectively reduce the uncontrolled loss of groundwater, reduce mine drainage costs, and protect the regional water resource balance.

[0040] In some embodiments, the layered grouting includes performing lower layer grouting, middle layer grouting, and upper layer grouting sequentially from bottom to top on the grouting layer; the lower layer grouting involves grouting the lower layer within the grouting layer to create a base, the grouting material for the lower layer grouting is a fast-setting two-component grout, and the grouting end pressure is 0.8 MPa to 2 MPa; the middle layer grouting involves grouting the middle layer within the grouting layer to fill it, the grouting material for the middle layer grouting is fly ash cement grout, and the grouting end pressure is 2 MPa to 5 MPa; the upper layer grouting involves grouting the upper layer within the grouting layer to seal it, the grouting material for the upper layer grouting is clay cement grout, and the grouting end pressure is 2 MPa to 5 MPa.

[0041] The grouting layer can be divided into a lower layer, a middle layer, and an upper layer. The thickness of the upper and lower layers is 15m to 20m, and the remaining space of the grouting layer is the middle layer.

[0042] like Figure 5 As shown, layered grouting involves first grouting the lower layer, then the middle layer, and finally the upper layer at the grouting layer corresponding to the target working surface within each fracture step of the roof slab. This approach balances grouting cost, efficiency, and effectiveness. The specific grouting operation for each layer can be achieved through branch holes in each layer. The lateral range of layered grouting must cover the fracture area of ​​the roof slab at the target working surface.

[0043] Lower-layer grouting is a process of injecting grout to create a base for the lower layers. The grouting material for lower-layer grouting is a fast-setting two-component grout. For example, the A component of the fast-setting two-component grout is ordinary silicate cement grout, and the B component is an accelerator, such as water glass, calcium chloride, or aluminate. The grouting end pressure for lower-layer grouting is 0.8 MPa to 2 MPa. Lower-layer grouting can quickly seal and create a base for the bottom of the grouting layer, avoiding large amounts of grout leakage during subsequent grouting, which would cause waste and reduce the sealing effect.

[0044] Intermediate grouting is a grouting and filling process targeting the middle layer. The grouting material for intermediate grouting is fly ash cement grout, and the grouting end pressure is 2MPa to 5MPa. Intermediate grouting can achieve large-area crack filling with low cost and high efficiency.

[0045] Upper-layer grouting is used to seal the upper layers. The grouting material for upper-layer grouting is clay-cement grout. Although the cost is slightly higher, it has a strong effect on sealing cracks. The grouting end pressure is 2MPa to 5MPa. The upper layer is closest to the aquifer. Upper-layer grouting can effectively isolate the aquifer and prevent water inrush and leakage. At the same time, it can also supplement the sealing of the aforementioned middle-layer grouting and improve the grouting effect.

[0046] In some embodiments, the top plate breaking step distance includes the initial pressure step distance. and period to reduce step size ,in, , , The tensile strength of the basic top rock layer, The thickness of the basic top rock layer, This represents the uniformly distributed load of the overlying rock layer on the basic top rock layer.

[0047] like Figure 4 As shown, after the start of mining, the step distance at which the first roof fracture occurs along the mining direction is the initial pressure step distance. Subsequently, as mining progressed, the step distance for each roof breach was used as a periodic adjustment step distance. .

[0048] In some embodiments, after the roof of the target working face breaks at each roof breaking step distance during the mining process, layered grouting is performed on the grouting layer corresponding to the target working face within that roof breaking step distance, including:

[0049] S401, such as Figure 2 As shown, when the distance of the retreat reaches the initial pressure step distance for the first time, after the top plate of the target working face breaks within the initial pressure step distance, the grouting layer corresponding to the target working face within the initial pressure step distance is grouted in layers.

[0050] S402, such as Figure 3 and Figure 4 As shown, after each time the distance of the retreat reaches the cycle step distance, after the top plate of the target working face breaks within the cycle step distance, the grouting layer corresponding to the target working face within the cycle step distance is grouted in layers.

[0051] Layered grouting based on the initial grouting step distance and the cycle grouting step distance can ensure grouting stability and improve grouting efficiency.

[0052] In some embodiments, the step of determining the grouting layer based on the simulated development characteristics of the water-conducting fracture zone and the formation distribution characteristics includes: S403, determining the grouting hole based on the simulated development characteristics of the water-conducting fracture zone.

[0053] Based on the simulated development characteristics of the water-conducting fracture zone, the highest point of the water-conducting fracture zone was determined, and grouting holes were vertically constructed on the ground corresponding to the highest point.

[0054] In some embodiments, the step of mining the target working face includes:

[0055] S404. A water pressure test is conducted through the grouting hole to obtain the test value of Lvrong.

[0056] S405. When the test Lvrong value is greater than or equal to the preset Lvrong value, auxiliary grouting is performed on the grouting layer.

[0057] After the mining begins, a water pressure test can be conducted through the grouting hole to determine whether the actual water-conducting fracture zone has developed to the main aquifer at the grouting layer. If it is determined that the main aquifer has developed, auxiliary grouting can be carried out before formal layered grouting to reduce rock movement, accelerate roof stability, seal some large water-conducting fractures, reduce downhole water inflow, ensure safety, reduce the amount of grout used in subsequent layered grouting, and improve grouting effect.

[0058] Specifically, a pressure test can be conducted to obtain the Lurong value. When the Lurong value is greater than or equal to the preset Lurong value, it indicates that the actual water-conducting fracture zone has developed to the main aquifer, and auxiliary grouting can be carried out. The preset Lurong value is, for example, 5 Lu. The grouting material for auxiliary grouting is gangue-fly ash slurry. The mass ratio of fly ash to coal gangue can be 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, etc. The grouting end pressure for auxiliary grouting is 4MPa to 5MPa. The auxiliary grouting material has low cost, can fill large-sized aggregates, and requires less material compared to layered grouting.

[0059] Based on this, auxiliary grouting can be carried out before the layered grouting operation of each section of the roof slab fracture distance, so as to reduce the amount of grout used in subsequent layered grouting and improve the grouting effect.

[0060] In some embodiments, after the roof of the target working face breaks at each roof breaking step distance during the mining process, layered grouting is performed on the grouting layer corresponding to the target working face within that roof breaking step distance, including:

[0061] S406. Surface movement monitoring is performed on the target working face to obtain the surface subsidence difference over a preset time period.

[0062] After mining begins, methods such as optical fiber and borehole water level can be used to monitor the spatiotemporal information of the development range of the water-conducting fracture zone. When the height of the water-conducting fracture zone develops to the expected maximum height, the surface movement of the target working face can be monitored. Alternatively, after mining begins, the surface movement of the target working face can be monitored to determine the stability of the formation after the subsequent roof fracture.

[0063] Specific surface movement monitoring can be as follows Figure 6 As shown, observation stations are set up corresponding to the target working face. The observation stations monitor the observation points on the strike line and dip line to accurately capture the dynamics of surface movement and provide a data basis for subsequent analysis.

[0064] like Figure 7As shown, the subsidence depth of each observation point at each time point can be obtained through monitoring. Within a preset period, such as a one-week interval, the difference in surface subsidence within a preset time period can be obtained by calculating the difference between the subsidence depths of two observation points.

[0065] S407. Each time the distance of the mining reaches the roof breaking step distance, the roof of the target working face breaks, and the ground subsidence difference is less than or equal to the preset subsidence difference value, the grouting layer corresponding to the target working face within the roof breaking step distance is grouted in layers.

[0066] When the distance of the mining reaches the roof breaking step distance, if the surface subsidence difference is less than or equal to the preset subsidence difference after the roof breaks, such as 30mm, it means that the strata are relatively stable after mining. At this time, the layered grouting operation can be carried out, which can greatly improve the grouting effect and reduce the grouting cost.

[0067] In some embodiments, the step of mining the target working face includes:

[0068] S408. Obtain test results by performing borehole television testing or fiber optic sensor testing through the grouting hole.

[0069] S409. Verify the results of the water pressure test or the surface movement monitoring results based on the test results.

[0070] After mining begins, in addition to water pressure tests, borehole television tests or fiber optic sensor tests can be conducted through grouting holes to obtain corresponding test results, in order to verify the results of water pressure tests or surface movement monitoring, determine whether the water-conducting fracture zone has developed to the main aquifer, or determine whether the strata are stable after the roof has fractured.

[0071] Specifically, the test results are, for example, borehole television images. From the images, the actual development range of the water-conducting fracture zone can be visually determined, thereby judging whether the water-conducting fracture zone has developed to the main aquifer. Based on the borehole television images at different times, the degree of fracture change can be determined, thereby judging whether the strata are stable after the top plate is fractured.

[0072] The test results can be fiber optic sensing of fracture signals. The continuity of the signal can be used to determine whether the water-conducting fracture zone has developed into the main aquifer. The test results can also be fiber optic sensing of displacement signals, which can be used to determine whether the formation is stable after the roof fractures.

[0073] This coal seam sandstone roof-based water-conserving mining method, which involves grouting fractures during mining, treats water-conducting fractures as they are mined. Through real-time monitoring, dynamic management, and precise control, it achieves multiple benefits in terms of safety, economy, and environmental protection. Its core advantage lies in proactively preventing water inrush accidents: by using grouting and curtain interception techniques to promptly block water-conducting fractures, it prevents groundwater or old working water from flowing into the goaf, significantly reducing the risk of water inrush and ensuring the safety of personnel and equipment. Simultaneously, this technology effectively reduces the uncontrolled loss of groundwater, lowers mine drainage costs, and protects the regional water resource balance. By controlling the development range of fractures, it prevents damage to key aquifers or the penetration of surface water bodies, avoiding surface subsidence, water loss, and pollutant diffusion, thus mitigating ecological impacts. Economically, the phased optimization of treatment investment during mining avoids high later-stage emergency rescue costs and reduces production interruptions caused by water inrushes, improving mining continuity and economic efficiency. Technically, relying on microseismic monitoring, borehole inspection, and hydrological dynamic analysis, this model enables real-time tracking and precise treatment of fracture development. Combined with strategies such as advanced grouting and segmented treatment, it balances efficiency and cost. Furthermore, this model transforms traditional passive emergency response into proactive prevention and control, aligning with the concept of green mining. By reducing water hazards and ecological damage, it promotes sustainable development, ultimately achieving the synergistic goals of safe and efficient mining, resource conservation, and environmental protection.

[0074] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0075] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0076] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, well-known power / ground connections to other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be illustrated in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be entirely within the understanding of those skilled in the art). While specific details have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application may be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0077] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. The embodiments of this application are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, characterized in that, include: Obtain the hydrogeological parameters of the target working face in the coal mine; Based on the hydrogeological parameters, determine the top plate fracture step distance of the target working face, determine the stratigraphic distribution characteristics above the target working face, and determine the simulated development characteristics of the water-conducting fracture zone of the target working face; Determining the grouting location based on the simulated development characteristics of the water-conducting fracture zone and the stratigraphic distribution characteristics includes: determining the maximum development range of the water-conducting fracture zone based on the simulated development characteristics of the water-conducting fracture zone; and selecting the topmost aquitard located within the maximum development range of the water-conducting fracture zone as the grouting location based on the stratigraphic distribution characteristics. The target working face is mined back, and each time the mining distance reaches the roof breaking step distance, after the roof of the target working face breaks, the grouting layer corresponding to the target working face within the roof breaking step distance is grouted in layers until the entire target working face is mined back and all the grouting layers corresponding to the target working face are grouted in layers, then the operation ends; wherein, the layered grouting includes performing lower layer grouting, middle layer grouting and upper layer grouting in the grouting layer from bottom to top; the lower layer grouting is the grouting layer... The lower layer within the grouting layer is grouted to create a base. The grouting material for the lower layer is a fast-setting two-component grout, and the grouting end pressure is 0.8 MPa to 2 MPa. The middle layer grouting involves filling the intermediate layer within the grouting layer with grout. The grouting material for the middle layer is fly ash cement grout, and the grouting end pressure is 2 MPa to 5 MPa. The upper layer grouting involves sealing the upper layer within the grouting layer with grout. The grouting material for the upper layer is clay cement grout, and the grouting end pressure is 2 MPa to 5 MPa.

2. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 1, is characterized in that... The top plate breaking step distance includes the initial pressure step distance. and period to reduce step size ,in, , , The tensile strength of the basic top rock layer, The thickness of the basic top rock layer, This represents the uniformly distributed load of the overlying rock layer on the basic top rock layer.

3. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 2, is characterized in that... Each time the distance of the retreat reaches the roof breaking step distance, after the roof of the target working face breaks, layered grouting is performed on the grouting layer corresponding to the target working face within the roof breaking step distance, including: When the distance of the retreat reaches the initial pressure step distance for the first time, and the top plate of the target working face breaks within the initial pressure step distance, the grouting layer corresponding to the target working face within the initial pressure step distance is grouted in layers. Subsequently, each time the distance of the retreat reaches the cycle step distance, after the roof of the target working face breaks within the cycle step distance, the grouting layer corresponding to the target working face within the cycle step distance is grouted in layers.

4. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 1, is characterized in that... The step of determining the grouting layer based on the simulated development characteristics of the water-conducting fracture zone and the formation distribution characteristics includes: determining the grouting hole based on the simulated development characteristics of the water-conducting fracture zone; The step of mining the target working face includes: conducting a water pressure test through the grouting hole to obtain the test Lvrong value; and when the test Lvrong value is greater than or equal to the preset Lvrong value, performing auxiliary grouting on the grouting layer.

5. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 4, is characterized in that... The auxiliary grouting material is gangue-fly ash slurry, and the grouting end pressure is 4MPa to 5MPa; the preset Lv value is 5Lu.

6. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 1, is characterized in that... Each time the distance of the retreat reaches the roof breaking step distance, after the roof of the target working face breaks, layered grouting is performed on the grouting layer corresponding to the target working face within the roof breaking step distance, including: The ground movement of the target working face is monitored to obtain the ground subsidence difference within a preset time period; Each time the distance of the mining reaches the roof breaking step distance, the roof of the target working face breaks, and the ground subsidence difference is less than or equal to the preset subsidence difference value, the grouting layer corresponding to the target working face within the roof breaking step distance is grouted in layers.

7. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 6, is characterized in that... The preset time is one week, and the preset subsidence difference is 30mm.

8. The method for water-conserving coal mining based on mining-induced fracture grouting in sandstone roof during mining, as described in claim 4, is characterized in that... The step of mining the target working face includes obtaining test results by performing borehole television testing or fiber optic sensor testing through the grouting hole. The results of the pressure water test or the surface movement monitoring are verified based on the test results.

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