Double-under-pressure mining method for top and bottom plates of ore deposit

Abstract

The invention relates to a double-under-pressure mining method for a top plate and a bottom plate of an ore deposit. The ore deposit top and bottom plate double-belt pressure mining method comprises the steps that the vertical distance between an ore body and a top plate and bottom plate indirect strong aquifer is determined, and the water pressure guide rising belt height of the top plate and bottom plate indirect strong aquifer is calculated; determining the damage depth of ore body mining to a roof and a bottom plate, calculating the thickness of an effective water-resisting belt, and evaluating the water-resisting capability of water-resisting layers of the roof and the bottom plate of the mine plant; determining the lower limit elevation of ore body mining according to a comparison result of the thickness of the effective water insulation belt and a safety threshold value; and drawing an ore deposit mining area map through the three-dimensional space model of the mining area stratum. According to the scheme provided by the invention, by determining the vertical distance from the ore body to the top and bottom plate indirect strong aquifer, calculating the height of the water pressure guide rising zone, and evaluating the damage depth of mining to the top and bottom plates and the thickness of the effective waterproof zone, accurate evaluation and safety control of the top and bottom plate bidirectional high-pressure water disaster threat in the metal mine ultra-deep mining process are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of safe mining of mines, in particular to a double-belt pressure mining method of ore deposit roof and floor. BACKGROUND

[0002] Many metal deposits in China have entered the stage of super-deep mining. With the continuous decline of mining elevation, the shaft and roadway engineering is far below the local minimum erosion datum, and the roof and floor of the ore body are simultaneously threatened by the huge water pressure of the high-pressure aquifer. Under the complex hydrogeological conditions of "double-belt pressure", mining faces unprecedented water inrush risks, which seriously restricts the safe and efficient recovery of deep mineral resources.

[0003] At present, in the field of coal mines, the "water inrush coefficient method" is generally used for the risk evaluation of floor confined water. However, this method has significant limitations when applied to super-deep mining in metal mines, and is highly empirical and has insufficient applicability. The water inrush coefficient method and its critical value are mainly derived from the statistical experience of coalfields, while the rock mechanics properties, ore occurrence, and complexity of geological structure of metal mines are significantly different from those of coal mines. Directly applying the critical value is often too conservative or inaccurate. The traditional water inrush coefficient calculation only considers water pressure and aquifer thickness, and does not fully consider key factors such as the damage depth of mine pressure on the aquifer, the richness of the aquifer, the height of the guide and uplift zone, and the development of structures, resulting in a relatively rough evaluation result.

[0004] Although some researchers have improved the water inrush coefficient formula by introducing factors such as damage depth and water richness, these improved methods have not been widely adopted by regulations and are difficult to effectively apply in actual engineering due to the difficulty in accurately obtaining key parameters such as equivalent thickness conversion coefficient and guide and uplift zone height.

[0005] Therefore, there is a need for a safety mining method that is suitable for the characteristics of super-deep mining in metal mines, can comprehensively consider the threat of double-direction high-pressure water damage from the roof and floor, and combines quantitative and qualitative methods to scientifically determine the lower limit of safe mining and ensure mine safety production. SUMMARY

[0006] To solve or partially solve the problems in the related art, the present application provides a double-belt pressure mining method of ore deposit roof and floor, aiming to solve the technical problem of safe mining under super-deep comprehensive double-belt pressure in metal mines.

[0007] The present application provides a double-belt pressure mining method of ore deposit roof and floor, comprising: determining the vertical distance of the intermediate strong aquifer between the ore body and the roof and floor, and calculating the water pressure guide and uplift zone height of the intermediate strong aquifer between the roof and floor; determining the damage depth of the roof and floor caused by ore mining, calculating the effective aquifer thickness, and evaluating the water blocking capacity of the roof and floor aquifer in the mine; According to the comparison result of the effective water-resisting zone thickness and the safety threshold, the lower limit elevation of the ore body mining is determined; Through the three-dimensional space model of the stratum in the mining area, contour maps of the vertical distance of the composite strong aquifer, the height of the water pressure guide zone, the damage depth of the ore body mining, the thickness of the water-resisting zone and the lower limit elevation of the mining are drawn, and finally the mining area map of the deposit is drawn by using the water head pressure acting on the roof and floor.

[0008] Optionally, in some embodiments, the vertical distance of the ore body to the strong aquifer between the roof and the floor is determined, including: The three-dimensional modeling software of deep exploration geology is used to integrate all drilling, profile, geophysical prospecting and underground logging data, to obtain accurate mine point data with drilling as the core, to extend with geophysical prospecting, to infer the spatial distribution of stratum, and to verify the final true distance with underground exposure. A refined three-dimensional geological model of the mining area is constructed, and the vertical distance of the ore body to the strong aquifer between the roof and the floor at any point in the mining area is visually queried and calculated.

[0009] Optionally, in some embodiments, the water pressure guide zone height of the strong aquifer between the roof and the floor is calculated, including: The water pressure guide zone height refers to the maximum vertical height of the high-pressure water head of the confined aquifer penetrating upward along the fissure or weak structure zone in the water-resisting zone under natural or mining disturbance conditions; The water pressure guide zone height is indirectly determined by actively applying engineering means to test the impermeability of the water-resisting zone. Specifically, a drilling water injection test is performed, a water stop plug is lowered into the water-resisting zone section in the drilling to isolate a test section, then water is pressurized to the test section, and the relationship between the water absorption and the pressure value is observed. By analyzing the pressure-flow curve, the development of the fissure and the permeability are determined, and the height of the guide zone is indirectly inferred from the results of multiple test sections. If the unit water absorption suddenly increases at a certain depth, it indicates that the fissure is well developed above this depth, and a guide channel may have been formed, thereby delineating the top boundary of the guide zone. The underground water discharge test and water level dynamic observation are performed on the target aquifer in the underground drilling for a large scale and a long time, while continuously observing the water pressure of itself, the water level of adjacent aquifers and the water inrush point underground. The response time, drawdown amplitude and correlation of the water level of each observation point during the water discharge process are analyzed to determine the highest position of the fissure fractured and dissolved and expanded by water pressure. The height difference between this position and the top boundary of the aquifer is the water pressure guide zone height.

[0010] Optionally, in some embodiments, the damage depth of the ore body mining to the roof and the floor is determined, including: According to the mining depth, the working face oblique length, the mining method and the roof and floor lithology of the mining area itself, the corresponding damage depth empirical formula is obtained through statistical analysis: (1) wherein, represents the damage depth, H represents the mining depth, L represents the working face oblique length, a, b, c represent the empirical coefficients obtained by regression analysis according to the measured data of the mine area.

[0011] Optionally, in some embodiments, the effective water-resisting zone thickness is calculated, and the water-resisting capacity evaluation of the mine roof and floor water-resisting layer is performed, including: The effective water-resisting zone refers to the part below the mining-induced water flowing fractured zone of the ore body floor and above the floor aquifer, the rock stratum maintains the integrity before mining, and its water-resisting performance is not affected; The main feature of the effective water-resisting zone is to maintain the continuity and integrity of the rock stratum before mining, and the water-resisting performance does not change. Although the rock stratum in the effective water-resisting zone is subjected to the action of abutment pressure and produces elastic or plastic deformation, it still maintains continuity. Under the condition of a larger thickness, it can still prevent floor water inrush. The calculation formula is: (2) wherein, represents the effective water-resisting zone thickness; h represents the total thickness of the water-resisting roof or floor; represents the mining damage zone thickness; represents the water pressure guide height.

[0012] Optionally, in some embodiments, the water-resisting capacity evaluation of the mine roof and floor water-resisting layer is performed, including: The water-resisting capacity evaluation of the mine roof and floor water-resisting layer is performed, and the water-resisting coefficient of the stratum is calculated according to the linear attenuation of the pressure water head: The calculation formula of the fractured zone guide height is: The fractured zone guide height refers to the maximum vertical height of the high-pressure water in the confined aquifer, which penetrates and migrates upward along the natural fractures, tectonic fracture zones and other weak surfaces in the water-resisting rock stratum by relying on its pressure; The weak link of the water-resisting layer is confirmed through the fractured zone guide height, the effective water-resisting layer thickness is corrected, and the stability of the water-resisting capacity under mining disturbance is predicted.

[0013] Optionally, in some embodiments, the lower limit elevation of the ore body mining is determined, including: The critical water inrush pressure is calculated according to the critical water inrush coefficient, and then converted into the water head height, and the lower limit elevation of the ore body mining is iteratively calculated: (3) (4) wherein, represents the effective water-resisting capacity, represents the critical water inrush pressure, represents the residual water-resisting capacity, represents the water pressure value borne by the water-bearing layer of the roof or floor, represents the regional critical water inrush coefficient; The regional critical water inrush coefficient is generally between 0.060-0.150 MPa / m, and the lower limit elevation of the ore body mining is iterated under the condition that the actual water inrush coefficient is less than the safety value of the regional critical water inrush coefficient. First, a mining elevation and a mining scheme are preset, the mining damage zone thickness and the effective water-resisting zone thickness under the scheme are calculated, and whether the actual water inrush coefficient meets the safety condition is checked. If safe, the elevation can be used as the temporary lower limit of mining, and the scheme can be optimized to mine deeper resources. If not safe, the lower limit of mining must be reset, and the mining elevation is increased. Through repeated simulation iteration and calculation, a comprehensive optimal safety lower limit elevation of mining under the technical and economic conditions is found.

[0014] The technical scheme provided by the present application can include the following beneficial effects: By determining the vertical distance of the ore body to the indirect strong water-bearing layer between the roof and floor, calculating the water pressure guide-up zone height, evaluating the damage depth of the roof and floor and the thickness of the effective water-resisting zone, and performing multi-parameter fusion analysis and visual expression based on the three-dimensional geological model, the precise evaluation and safety control of the roof and floor bidirectional high-pressure water hazard threat in the process of super-deep mining of the metal mine are realized. The defects of strong experience, single parameter and insufficient applicability of the traditional water inrush coefficient method in the application of the metal mine are overcome, the scientificity and reliability of the determination of the lower limit elevation of mining are significantly improved, the water inrush risk is effectively reduced, the safety production of the mine is ensured, and the safe and efficient recovery of resources under the complex hydrogeological conditions is applicable.

[0015] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout the several views, and in which the exemplary embodiments of the present application are shown.

[0017] Figure 1 is a flowchart of the roof and floor double-zone pressure mining method of the deposit shown in the embodiments of the present application. DETAILED DESCRIPTION

[0018] Embodiments of the present application will be described in more detail by referring to the drawings. Although the embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0019] It should be understood that, although the terms "first", "second", "third", etc. can be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one piece of information from another piece of information of the same type. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present application. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0020] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application.

[0021] Unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be interpreted broadly, for example, they can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0022] At present, in the field of coal mines, the risk evaluation of floor confined water generally uses the "water inrush coefficient method". However, this method has significant limitations when applied to super-deep mining in metal mines, is highly empirical, and has insufficient applicability. The water inrush coefficient method and its critical value are mainly derived from the statistical experience of coal fields, while the rock mechanical properties, ore body occurrence, and complexity of geological structure of metal mines are significantly different from those of coal mines. Directly applying the critical value is often too conservative or inaccurate. The traditional water inrush coefficient calculation only considers water pressure and aquiclude thickness, and does not fully consider key factors such as the damage depth of the aquiclude, the richness of the aquifer, the height of the water pressure guide, and the development of the structure. The evaluation results are relatively rough. Although some researchers have improved the water inrush coefficient formula by introducing factors such as damage depth and water richness, these improved methods have not been widely adopted by regulations and are difficult to effectively apply in actual engineering due to the difficulty in accurately obtaining key parameters such as equivalent thickness conversion coefficient and water pressure guide height.

[0023] To solve the above problems, the embodiment of the present application provides a double-belt pressure mining method for ore deposit roof and floor, which can determine the vertical distance between the ore body and the indirect strong aquifer between the roof and the floor, calculate the water pressure guide height, evaluate the damage depth and effective aquifer thickness of the roof and floor caused by mining, and perform multi-parameter fusion analysis and visual expression based on a three-dimensional geological model, thereby realizing accurate evaluation and safety control of the roof and floor double-direction high-pressure water hazard threat in the process of super-deep mining in metal mines. The double-belt pressure mining method for ore deposit roof and floor overcomes the defects of the traditional water inrush coefficient method, such as strong empiricism, single parameter, and insufficient applicability, significantly improves the scientificity and reliability of the determination of the lower limit elevation of mining, effectively reduces the risk of water inrush, ensures the safety of mine production, and is suitable for safe and efficient recovery of resources under complex hydrogeological conditions.

[0024] The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0025] Figure 1 is a flowchart of the double-belt pressure mining method for ore deposit roof and floor shown in the embodiment of the present application.

[0026] Referring to Figure 1 A double-belt pressure mining method for ore deposit roof and floor, comprising: S101, determining the vertical distance between the ore body and the indirect strong aquifer between the roof and the floor, and calculating the water pressure guide height of the indirect strong aquifer between the roof and the floor; Specifically, determining the vertical distance between the ore body and the indirect strong aquifer between the roof and the floor comprises: Using deep exploration geology three-dimensional modeling software, integrating all drilling, profile, geophysical prospecting, and underground logging data, obtaining accurate mine point data with drilling as the core, extending with geophysical prospecting, inferring the spatial distribution of strata, and verifying the final true distance with underground exposure; The fine three-dimensional geological model of the mining area is constructed, and the vertical distance between the ore body and the top and floor of the aquifer at any point in the mining area is visually queried and calculated.

[0027] Specifically, the height of the water pressure guide zone between the roof and the floor is calculated, including: The height of the water pressure guide zone refers to the maximum vertical height of the high-pressure water head of the confined aquifer that penetrates upward along the fissures or weak structural zones in the aquifer under natural or mining disturbance conditions; The impermeability of the aquifer is tested by actively applying engineering means to indirectly determine the height of the water pressure guide zone. Specifically, a water stop plug is placed in the aquifer section in the borehole to isolate a test section, and then water is pressurized into the test section to observe the relationship between the water absorption and pressure value. By analyzing the pressure-flow curve, the development of the fissures and the permeability are determined, and the height of the guide zone is indirectly inferred from the results of multiple test sections. If the unit water absorption suddenly increases at a certain depth, it indicates that the fissures above that depth are well developed and may have formed a guide channel, thereby delineating the top boundary of the guide zone. The water level dynamic observation and the underground water discharge test are carried out to discharge a large amount of water from the target aquifer in the underground borehole for a long time, while continuously observing the water pressure of itself and the water level changes of adjacent aquifers and underground water inrush points. The response time, drawdown amplitude and correlation of the water level of each observation point during the water discharge process are analyzed to determine the highest position of the fissures fractured by water pressure and dissolved and expanded. The height difference between this position and the top boundary of the aquifer is the height of the water pressure guide zone.

[0028] S102, determine the damage depth of the roof and floor caused by the mining of the ore body, calculate the thickness of the effective aquifer, and evaluate the water resistance capacity of the roof and floor aquifer in the mine; Specifically, the damage depth of the roof and floor caused by the mining of the ore body is determined, including: According to the mining depth, working face oblique length, mining method, roof and floor lithology of the mining area, the corresponding damage depth empirical formula is obtained through statistical analysis: (1) In the formula, H represents the damage depth, L represents the working face oblique length, and a, b, c represent the empirical coefficients obtained by regression analysis according to the measured data of the mining area.

[0029] Specifically, the thickness of the effective aquifer is calculated, including: The effective aquifer refers to the part below the mining-induced water-conducting fissure zone of the ore body floor and above the floor aquifer, which maintains the integrity of the rock before mining and its water resistance performance is not affected; The main feature of the effective water-resisting zone is to maintain the continuity of the rock stratum before mining, and the water-resisting performance does not change. Although the rock stratum in the effective water-resisting zone is subjected to the supporting pressure and produces elastic or plastic deformation, it can still maintain continuity. Under the condition of a larger thickness, the floor water inrush can still be prevented. The calculation formula is: (2) In the formula, represents the thickness of the effective water-resisting zone; h represents the total thickness of the water-resisting roof or floor; represents the thickness of the mining damage zone; represents the height of the water pressure guide rise zone.

[0030] Specifically, the water-resisting ability of the mine roof and floor water-resisting layer is evaluated, including: The water-resisting ability of the mine roof and floor water-resisting layer is evaluated, and the water-resisting coefficient of the stratum is calculated according to the linear attenuation of the pressure water head: The high-pressure water in the roof and floor is attenuated due to the barrier of the rock stratum, and the calculation formula of the fissure guide high zone is: The fissure guide high zone refers to the maximum vertical height of the high-pressure water in the confined aquifer, which penetrates and migrates upward along the natural fissures, tectonic fracture zones and other weak surfaces in the water-resisting rock stratum by relying on its pressure; The weak link of the water-resisting layer is confirmed through the fissure guide high zone, the thickness of the effective water-resisting layer is corrected, and the stability of the water-resisting ability under mining disturbance is predicted.

[0031] S103, determining the lower limit elevation of the ore body mining according to the comparison result of the thickness of the effective water-resisting zone and the safety threshold; Specifically, the lower limit elevation of the ore body mining is determined, including: The critical water inrush pressure is calculated according to the critical water inrush coefficient, and then converted into the water head height, and the lower limit elevation of the ore body mining is iteratively calculated: (3) (4) In the formula, represents the effective water-resisting ability, represents the critical water inrush pressure, represents the residual water-resisting ability, represents the water pressure value borne by the roof or floor aquifer, represents the regional critical water inrush coefficient; The regional critical water inrush coefficient is generally between 0.060-0.150 MPa / m, and the lower limit of the mining height of the ore body is iterated under the condition that the actual water inrush coefficient is less than the safety value of the regional critical water inrush coefficient. First, a mining height and a mining scheme are preset, the mining damage zone thickness and the effective water-resisting zone thickness under the scheme are calculated, and whether the actual water inrush coefficient meets the safety condition is checked. If yes, the height can be used as the temporary lower limit of mining, and the scheme can be optimized to mine deeper resources. If not, the lower limit of mining must be reset, and the mining height is increased. Through repeated simulation iteration and calculation, a comprehensive optimal safety lower limit of mining height under the technical and economic conditions is found.

[0032] In S104, the vertical distance of the composite strong aquifer, the height of the ascending zone, the mining damage depth of the ore body, the thickness of the water-resisting layer, and the contour map of the lower limit of mining height are drawn by using the three-dimensional space model of the stratum in the mining area. Finally, the water head pressure acting on the roof and floor is used to draw the mining area map of the deposit.

[0033] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application, or improvement of the technology in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A method for dual-pressure mining of the roof and floor of an ore deposit, characterized in that, include: Determine the vertical distance from the ore body to the strong aquifer between the top and bottom plates, and calculate the height of the water pressure conduction zone between the strong aquifers between the top and bottom plates; Determine the depth of damage to the roof and floor during ore body mining, calculate the effective water-resistant zone thickness, and evaluate the water-blocking capacity of the roof and floor water-resistant layers in the mine. Based on the comparison between the effective water-retaining zone thickness and the safety threshold, the lower limit elevation for ore body mining is determined; Using a three-dimensional spatial model of the strata in the mining area, contour maps were drawn to show the vertical distance of the composite strong aquifer, the height of the lifting zone, the depth of ore body mining damage, the thickness of the aquitard, and the lower limit elevation of mining. Then, using the water head pressure acting on the top and bottom plates, a map of the mining area of ​​the deposit was finally drawn.

2. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, The determination of the vertical distance from the ore body to the strong aquifer between the top and bottom plates includes: Using deep exploration 3D modeling software, all borehole, profile, geophysical and downhole logging data are integrated. Drilling is the core to obtain accurate mine point data, geophysical exploration is the extension to infer the spatial distribution of strata, and downhole exposure is the verification to confirm the final true distance. Construct a detailed three-dimensional geological model of the mining area, and visualize and calculate the vertical distance from the ore body to the aquifer between the top and bottom plates at any point in the mining area.

3. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, The calculation of the height of the water pressure rise zone of the strong aquifer between the top and bottom plates includes: The height of the hydraulic lift zone refers to the maximum vertical height by which high-pressure water head in a confined aquifer penetrates upward along the fissures or structural weak zones in the aquitard under natural or mining disturbance conditions. The water pressure rise zone height is indirectly determined by actively applying engineering methods to test the impermeability of the impermeable layer. Specifically, a borehole water injection test is conducted. A water-stop plug is placed below the impermeable layer section in the borehole to isolate a test section. Water is then injected into the test section, and the relationship between water absorption and pressure value is observed. By analyzing the pressure-flow curve, the development of fractures and permeability are judged. The height of the rise zone is indirectly inferred from the results of multiple test sections. If the unit water absorption suddenly increases at a certain depth, it indicates that the fractures above that depth are well developed and may have formed a rise channel, thereby delineating the top boundary of the rise zone. Downhole water release tests and dynamic water level observations involve large-scale, long-term water release from the target aquifer through a downhole borehole, while continuously monitoring its own water pressure, as well as the water level changes of adjacent aquifers and downhole water inflow points. The response time, drawdown magnitude, and correlation of water levels at each observation point during the water release process are analyzed to determine the highest position of the fractures that are split by water pressure and undergo dissolution and expansion. The height difference between this position and the top boundary of the aquifer is the height of the water pressure conduction zone.

4. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, Determining the depth of damage to the roof and floor caused by ore body mining includes: Based on the specific geological conditions of the mining area, including mining depth, working face length, mining method, and roof and floor lithology, a corresponding empirical formula for the failure depth is obtained through statistical analysis. （1） In the formula, H represents the depth of destruction, L represents the depth of mining, and a, b, and c represent empirical coefficients obtained from regression analysis based on measured data from the mining area.

5. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, The calculation of the effective water-resistant zone thickness is used to evaluate the water-blocking capacity of the water-resistant layers in the mine's roof and floor, including: The effective water-blocking zone refers to the part of the ore body that is located below the water-conducting fracture zone of the bottom plate and above the bottom aquifer, where the rock strata remain in their pre-mining state and their water-blocking performance is not affected. The main characteristics of an effective water-retaining zone are that it maintains the continuity and integrity of the pre-mining strata, and its water-blocking performance remains unchanged. Although the strata within the effective water-retaining zone are subjected to supporting pressure and undergo elastic or plastic deformation, they still maintain continuity. Under conditions of significant thickness, it can still prevent water inrush from the floor. The calculation formula is as follows: （2） In the formula, Indicates the effective waterproof strip thickness; h indicates the total thickness of the waterproof top or bottom plate; Indicates the thickness of the mining-induced damage zone; This indicates the height of the water pressure lift belt.

6. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, The evaluation of the water-blocking capacity of the waterproofing layers of the mine roof and floor includes: The water-blocking capacity of the roof and floor aquitards in a mine is evaluated, and the water-blocking coefficient of the formation is calculated based on the assumption of linear decay of pressure head. Due to the obstruction of rock strata, the water pressure of the high-pressure water in the top and bottom plates is attenuated. The formula for calculating the fracture conduction zone is as follows: The fractured conduction zone refers to the maximum vertical height at which high-pressure water in a confined aquifer can penetrate and migrate upward along weak surfaces such as natural fractures and tectonic fracture zones in the impermeable rock strata, relying on its pressure. By identifying the weak points of the aquitard through fractured high-conductivity zones, the effective aquitard thickness is adjusted, and the stability of the water-blocking capacity under mining disturbances is predicted.

7. The method for dual-pressure mining of the top and bottom plates of an ore deposit according to claim 1, characterized in that, The determination of the lower limit elevation for ore body mining includes: The critical water inrush pressure is calculated based on the critical water inrush coefficient, then converted into hydraulic head, and the lower limit elevation for ore body mining is iteratively calculated. （3） （4） In the formula, Indicates effective water-blocking capacity. Indicates the critical inrush pressure. Indicates residual water-blocking capacity. This indicates the water pressure value borne by the aquifer in the top or bottom slab. Indicates the critical inrush coefficient of the region; The regional critical water inrush coefficient is generally between 0.060 and 0.150 MPa / m. The iterative condition for the lower limit elevation of ore body mining is that the actual water inrush coefficient is less than the safe value of the regional critical water inrush coefficient. First, a mining elevation and mining scheme are preset. The thickness of the mining-induced failure zone and the effective water-retaining zone under the scheme are calculated, and the actual water inrush coefficient is checked to see if it meets the safety conditions. If it is safe, the elevation can be used as a temporary lower limit of mining, and the scheme can be optimized to mine resources at deeper depths. If it is not safe, the lower limit of mining must be reset and the mining elevation increased. Through repeated simulation iteration and calculation, a safe lower limit elevation of mining that is optimal under technical and economic conditions is found.

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