Coal mine filling mining floor damage depth dynamic prediction method and water inrush early warning method
By dynamically predicting the depth of coal seam floor failure and the risk of water inrush, and combining multidimensional information under backfilling mining conditions, the problem of poor prediction accuracy and early warning reliability in traditional methods has been solved, and safe and efficient control in the coal mining process has been achieved.
Patent Information
- Application Number
- CN202511954213.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-02-10
AI Technical Summary
Existing technologies cannot effectively address the risk of water inrush at the bottom of the coal seam under backfill mining conditions. Traditional static mechanical methods cannot take into account factors such as the mechanical behavior of the backfill, the dynamic advancement of the working face, and the accumulation of rock damage, resulting in poor prediction accuracy and early warning reliability.
By dynamically predicting the depth of coal seam floor failure, and combining the peak support stress, vertical stress, horizontal stress, maximum principal stress, and minimum principal stress of the filling mining area, considering the damage evolution of cohesion and internal friction angle, and combining the advance speed of the coal mining face, the depth of floor failure can be accurately predicted, and the potential risk of water inrush can be judged by combining the stress of the fault plane.
It enables accurate prediction of the depth of floor damage and early warning of water inrush risk during coal mine backfilling mining, improving the accuracy of prediction and engineering applicability, and meeting the needs of safe and efficient mining.
Smart Images
Figure CN121497434A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of coal mining technology, and in particular to a method for dynamic prediction of the depth of failure of the bottom plate in coal mine backfilling mining and a method for early warning of water inrush. Background Technology
[0002] In coal mining, the threat posed by high-pressure confined water in Ordovician limestone to the coal seam floor is becoming increasingly serious, and coal seam floor water inrush accidents have become a key bottleneck restricting safe and efficient mining. With increasing mining depth and intensity, the stress environment of the coal seam floor rock mass becomes more complex, making it more difficult to grasp the dynamic evolution of its failure depth and water inrush mechanism. Especially in recent years, the promotion and application of green mining technologies such as backfilling mining have rendered traditional methods for predicting the failure depth of the coal seam floor based on static mechanical conditions ineffective in addressing the water inrush risk caused by a combination of factors, including the mechanical behavior of the backfill, the dynamic advancement of the working face, and the accumulation of rock mass damage. Achieving accurate early warning faces significant challenges.
[0003] Currently, the industry mainly relies on three types of methods for predicting the depth of coal seam floor failure and assessing water inrush. The first type is the empirical formula method, which is simple and easy to use, but it is based on specific geological and mining conditions and has poor universality, especially failing to consider the redistribution characteristics of support pressure under backfill mining conditions. The second type is the numerical simulation method, which uses software such as FLAC3D and UDEC to simulate complex geological structures, but it consumes a lot of computational resources and has high sensitivity to parameter settings, making it difficult to meet the engineering needs of rapid and real-time early warning of risks during mining.
[0004] The third category is the analytical model method, which is based on elastic or plastic theory and has a certain theoretical foundation. However, its model assumptions are often too idealistic and generally suffer from common defects such as not systematically quantifying the support effect of the filling body, not introducing the dynamic influence of the propulsion speed on the evolution of rock mass damage, and not fully considering the activation mechanism of weak surfaces such as faults under dynamic load. Summary of the Invention
[0005] In view of this, the present disclosure provides a method for dynamic prediction of the failure depth of the bottom plate in coal mine backfilling mining and a method for early warning of water inrush, which can solve the problems of incomplete analysis results, poor prediction accuracy, poor reliability and timeliness of early warning in the existing static analysis method.
[0006] In a first aspect, embodiments of this disclosure provide a method for dynamically predicting the failure depth of the floor in coal mine backfilling mining, including: The peak support stress of the filling stope corresponding to the target coal seam is determined based on the target coal seam mining thickness, preset filling rate, and geological parameters of the target mining area; the target mining area includes the filling compaction zone, the coal body plastic zone, and the coal body elastic zone; Based on the peak value of the supporting stress in the filling stope, obtain the vertical stress at any point on the coal seam floor of the target mining area. Based on the vertical stress at any point on the coal seam floor of the target mining area, determine the horizontal stress at any point on the coal seam floor of the target mining area; Based on the vertical and horizontal stresses at any point on the coal seam floor of the target mining area, determine the maximum and minimum principal stresses of the target mining area. Based on the maximum principal stress, the minimum principal stress, and the advance speed of the coal mining face, the cohesive damage evolution information and internal friction angle damage evolution information of the coal seam floor are obtained, and the predicted damage depth corresponding to the current moment is determined.
[0007] Secondly, this disclosure also provides a method for early warning of sudden flooding, including: The predicted depth of damage at the current moment is obtained based on the dynamic prediction method for the depth of damage to the bottom plate of coal mine backfilling mining. Obtain the effective normal stress acting on the fault plane; Based on the predicted damage depth and the effective normal stress, a potential risk of water inrush is identified.
[0008] The method for dynamically predicting the depth of damage to the coal seam floor during backfilling mining disclosed in this application determines the peak value of the supporting stress in the backfilling stope corresponding to the target coal seam based on the target coal seam mining thickness, preset backfilling rate, and geological parameters. Based on the peak value of the supporting stress in the backfilling stope, the vertical stress at any point on the coal seam floor of the target mining area is obtained. Based on the vertical stress at any point on the coal seam floor of the target mining area, the horizontal stress at any point on the coal seam floor of the target mining area is determined. Based on the vertical and horizontal stresses at any point on the coal seam floor of the target mining area, the maximum and minimum principal stresses of the target mining area are determined. Based on the maximum and minimum principal stresses and the advance speed of the coal face, the cohesive damage evolution information and internal friction angle damage evolution information of the coal seam floor are obtained, and the predicted depth of damage at the current moment is determined. This application comprehensively considers multi-dimensional information, simulates the real mechanical damage evolution process of the coal seam floor during backfilling mining, and transforms the depth of damage from a static estimation into a dynamic prediction, enabling accurate prediction of the depth of floor damage during coal mine backfilling mining.
[0009] The above description is merely an overview of the technical solution disclosed herein. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this disclosure more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0010] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0011] Figure 1 This is a flowchart illustrating the dynamic prediction method for the failure depth of the coal mine backfill mining floor provided in this embodiment of the disclosure.
[0012] Figure 2 This is a flowchart illustrating the method for determining the peak support stress of the backfilled mining area corresponding to the target coal seam, as provided in an embodiment of this disclosure.
[0013] Figure 3 This is a flowchart illustrating a method for obtaining the vertical stress at any point on the coal seam floor of a target mining area, as provided in an embodiment of this disclosure.
[0014] Figure 4 This is a flowchart illustrating a method for obtaining horizontal stress at any point on the coal seam floor in a target mining area, as provided in an embodiment of this disclosure.
[0015] Figure 5 This is a flowchart illustrating a method for obtaining the predicted depth of damage at the current moment, as provided in an embodiment of this disclosure.
[0016] Figure 6 A curve showing the ratio of support stress of the filling variable parameter base plate provided in the embodiments of this disclosure.
[0017] Figure 7 A mechanical schematic diagram illustrating the combined action of deep backfilling mining, concealed bottom structure, and Ordovician limestone water, provided for embodiments of this disclosure. Detailed Implementation
[0018] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.
[0019] It should be understood that the following specific examples illustrate the implementation of this disclosure, and those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.
[0020] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.
[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0022] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.
[0023] Reference Figure 1 This application discloses a method for dynamically predicting the failure depth of the floor in coal mine backfilling mining, including: S100 determines the peak support stress of the filling stope corresponding to the target coal seam based on the target coal seam mining thickness, preset filling rate, and geological parameters.
[0024] S200: Based on the peak value of the supporting stress in the filling stope, obtain the vertical stress at any point on the coal seam floor of the target mining area; S300, based on the vertical stress at any point on the coal seam floor of the target mining area, determine the horizontal stress at any point on the coal seam floor of the target mining area; S400 determines the maximum and minimum principal stresses of the target mining area based on the vertical and horizontal stresses at any point on the coal seam floor. S500 obtains information on the cohesive damage evolution and internal friction angle damage evolution of the coal seam floor based on the maximum principal stress, minimum principal stress, and the advance speed of the coal mining face, and determines the predicted damage depth at the current moment.
[0025] Reference Figure 2 For S100, the method for determining the peak support stress in the backfilled stope corresponding to the target coal seam includes: S110, obtain the peak value of the advance support pressure corresponding to the mining face of the mined but unfilled area with similar geological conditions to the target coal seam.
[0026] S120, based on the peak value of the advance support pressure, the target coal seam mining thickness, and the preset filling rate, determines the maximum support pressure of an area with similar geological conditions to the target coal seam when it has been mined but not filled.
[0027] The maximum support pressure is A: ;in, This represents the peak value of the advance support pressure. The target coal seam mining thickness, For reference mining height, in this embodiment, the reference mining height is preferably 3m.
[0028] S130, obtain the maximum reduction in support pressure corresponding to a mined and fully compacted coal seam with similar geological conditions to the target coal seam.
[0029] S140, based on the reduction in maximum support pressure, the target coal seam mining thickness, and the preset filling rate, determine the reduction in maximum support pressure corresponding to the target mining area.
[0030] The reduction in maximum support pressure corresponding to the target mining area is : ;in, This represents the maximum reduction in support pressure corresponding to a fully compacted and mined coal seam with similar geological conditions to the target coal seam (as monitored on-site).
[0031] S150 is the basic efficiency coefficient of an area with similar geological conditions to the target coal seam when it is filled with pure gangue without cement.
[0032] S160, based on the basic efficiency coefficient, the cement slurry contribution coefficient, and the percentage of cementing material content, determine the filling material parameters corresponding to the target coal seam.
[0033] The filler material parameters are as follows : ; 0 < ≤0.5; where, The foundation efficiency coefficient is the result of filling with pure gangue without cement. The contribution coefficient of the binder slurry represents the increase in efficiency coefficient for each additional unit of binder content. It represents the percentage of cementitious material content, i.e., the ratio of cement to gangue used as filler.
[0034] S170, based on the maximum support pressure, the reduction in the maximum support pressure corresponding to the target mining area, and the parameters of the filling material, obtain the peak support stress of the filling mining area corresponding to the target coal seam.
[0035] The peak bearing stress in the backfilled stope corresponding to the target coal seam is : , The preset filling rate for the target coal seam (referring to the coal seam to be mined).
[0036] Further reference Figure 6 The figure shows the stress ratio curve of the filled variable parameter base plate controlled by the constructed filled variable parameter support pressure model. The figure also shows the different dosages of cementing material ( Under conditions of 5%, 10%, and 15%, the ratio of base plate support stress With fill rate The changing pattern. When all curves start from the same initial value, it indicates that the peak support pressure is the largest when there is no filling. As the filling rate increases, the curves gradually separate and show a downward trend. The higher the content of cementitious material, the greater the difference. The larger the fill ratio (the faster the curve decreases), the stronger the material properties and the more significant the bearing pressure attenuation effect. When the fill ratio approaches saturation (…), the curve decreases more rapidly, indicating stronger material properties and a more significant bearing pressure attenuation effect. When the content of cementitious material varies, the final pressure values corresponding to different dosages are significantly different. The curve reaches its lowest value, reflecting that the high-performance material has the best load-bearing capacity under high filling ratio conditions. Therefore, in this application... The preferred value is 15%.
[0037] Reference Figure 3 and Figure 7 The target mining area includes a backfilling and compaction zone, a coal plastic zone, and a coal elastic zone. The backfilling and compaction zone includes a fully backfilled and compacted zone and a partially backfilled and compacted zone. For S200, the method for obtaining the vertical stress at any point on the coal seam floor of the target mining area includes: S210, based on the target bottom density and the location of the coal seam floor, determine the initial vertical stress at any point on the coal seam floor when the target coal seam is not mined.
[0038] The initial vertical stress at any point on the bottom of the target coal seam before mining is: : ; It is the density of the formation (i.e., the average unit weight of the rock mass (N / m³)). This represents the depth at any point on the bottom of the coal seam.
[0039] S220, based on the peak value of the supporting stress in the filling stope, obtain the vertical stress increment at any point on the bottom of the coal seam in the filling compaction zone, the plastic zone of the coal body, and the elastic zone of the coal body, and record them as the first vertical stress increment, the second vertical stress increment, and the third vertical stress increment, respectively.
[0040] S230, based on the first vertical stress increment, the second vertical stress increment, and the third vertical stress increment, obtain the mining-induced vertical stress increment at any point on the coal seam floor of the target mining area.
[0041] The vertical stress increment caused by mining at any point on the coal seam floor in the target mining area is: : ;in, This is the first vertical stress increment. This is the second vertical stress increment. This is the third vertical stress increment.
[0042] S240: Based on the initial vertical stress at any point on the coal seam floor when the target coal seam is not mined and the incremental vertical stress at any point on the coal seam floor of the target mining area, obtain the vertical stress at any point on the coal seam floor of the target mining area.
[0043] The vertical stress at any point on the coal seam floor in the target mining area is : ;in, The vertical stress increment at any point on the coal seam floor in the target mining area is the portion transmitted from the support pressure. In this embodiment, the vertical stress is caused by both the mining support pressure and the weight of the overlying rock.
[0044] The method for obtaining the first vertical stress increment includes: A100, determine the stress corresponding to the compacted zone based on the peak support stress of the filling stope.
[0045] The stress corresponding to the compacted filling zone is : ; ; The proportional coefficient corresponding to the filling and compaction zone.
[0046] A200, based on the thickness of the aquitard corresponding to the target mining area, the vertical distance between the Ordovician limestone high-pressure water layer and the bottom of the aquitard, determines the first included angle corresponding to any point on the bottom plate of the coal seam in the filling and compaction zone.
[0047] The first included angle is : , The thickness of the aquitard corresponding to the target mining area. It is the vertical distance between the bottom of the high-pressure water layer and the water-resistant layer of the Ordovician limestone (i.e., the thickness of the fault zone in the vertical direction). This represents the lateral coordinate value of any point on the bottom of the coal seam located in the filling and compaction zone. This represents the vertical coordinate value of any point on the bottom plate of the coal seam located in the filling and compaction zone.
[0048] A300, based on the lateral distance from the boundary of the fully compacted filling zone to the coal face, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the Ordovician limestone high-pressure aquitard and the bottom of the aquitard, determine the first boundary angle corresponding to any point on the bottom of the coal seam in the compacted filling zone.
[0049] The first boundary angle is : ; The lateral distance (i.e., horizontal) from the boundary of the fully compacted zone to the coal face.
[0050] A400, based on the stress corresponding to the filling and compaction zone, the first included angle, and the first boundary angle, determine the first vertical stress increment.
[0051] The first vertical stress increment is : .
[0052] The method for obtaining the second vertical stress increment includes: B100, the stress corresponding to the plastic zone of the coal body is determined based on the peak support stress of the filling stope.
[0053] The stress corresponding to the plastic zone of the coal body is : ; ; This is the proportional coefficient corresponding to the plastic zone of the coal body.
[0054] B200, based on the thickness of the aquitard corresponding to the target mining area, the vertical distance between the Ordovician limestone high-pressure aquitard and the bottom of the aquitard, determines the second included angle corresponding to any point on the bottom plate of the coal seam in the plastic zone of the coal body.
[0055] The second included angle is : , This represents the lateral coordinate value of any point on the bottom portion of the coal seam located in the plastic zone of the coal body. This represents the vertical coordinate value of any point on the bottom plate of the coal seam located in the plastic zone of the coal body.
[0056] B300, based on the lateral length of the boundary of the plastic zone of the coal body, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the high-pressure aquitard layer of Ordovician limestone and the bottom of the aquitard, determines the second boundary angle corresponding to any point on the bottom plate of the coal seam in the plastic zone of the coal body.
[0057] The second boundary angle is : ; It is the lateral length (i.e., horizontal) of the boundary of the plastic zone of the coal body.
[0058] B400, based on the stress force, second included angle, and second boundary angle corresponding to the plastic zone of the coal body, determine the second vertical stress increment.
[0059] The second vertical stress increment is : .
[0060] The method for obtaining the third vertical stress increment includes: C100, the stress corresponding to the elastic zone of the coal body is determined based on the peak support stress of the filling stope.
[0061] The stress corresponding to the elastic zone of the coal body is : .
[0062] C200, based on the thickness of the aquitard corresponding to the target mining area, the vertical distance between the Ordovician limestone high-pressure water layer and the bottom of the aquitard, determines the third included angle corresponding to any point on the bottom plate of the coal seam in the elastic zone of the coal body.
[0063] The third included angle is : , This represents the lateral coordinate value of any point on the bottom portion of the coal seam located in the elastic zone of the coal body. This represents the vertical coordinate value of any point on the bottom plate of the coal seam located in the elastic zone of the coal body.
[0064] C300, based on the lateral length of the elastic zone of the coal body, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the Ordovician limestone high-pressure aquitard and the bottom of the aquitard, determines the third boundary angle corresponding to any point on the bottom plate of the coal seam in the elastic zone of the coal body.
[0065] The third boundary angle is : ; It is the lateral length (i.e., horizontal) of the elastic zone of the coal body.
[0066] C400, based on the stress corresponding to the elastic zone of the coal body, the third included angle, and the third boundary angle, determines the third vertical stress increment.
[0067] The third vertical stress increment is : .
[0068] Reference Figure 4 For S300, the method for obtaining the horizontal stress at any point on the coal seam floor in the target mining area includes: S310, based on the vertical stress increment caused by mining at any point on the coal seam floor of the target mining area, determine the horizontal stress increment caused by mining at any point on the coal seam floor of the target mining area.
[0069] The increment of the horizontal stress caused by mining at any point on the coal seam floor in the target mining area is : , It is Poisson's ratio.
[0070] S320, based on the vertical stress at any point on the coal seam floor of the target mining area and the incremental horizontal stress caused by mining at any point on the coal seam floor of the target mining area, determine the horizontal stress at any point on the coal seam floor of the target mining area.
[0071] The horizontal stress at any point on the coal seam floor in the target mining area is : ; The lateral pressure coefficient is denoted as . In this embodiment, the horizontal stress is determined by the vertical stress and the lateral pressure coefficient of the rock mass.
[0072] The maximum principal stress in the target mining area of S400 is The minimum principal stress is : ; ; ; ,in, For shear stress, This is the shear stress coefficient.
[0073] Reference Figure 5 For S500, the method for obtaining the predicted damage depth at the current moment specifically includes: S510, based on the maximum principal stress, minimum principal stress, and the advance speed of the coal mining face, obtains the damage function of the coal seam floor rock mass as the advance speed of the coal mining face changes.
[0074] The damage function is : ; .
[0075] in, The damage acceleration index, As the damage rate baseline, The stress sensitivity index, This refers to the advance speed of the coal mining face.
[0076] Furthermore, the damage acceleration index is preferably in the range of 1.5 to 3.0, and the damage rate baseline is preferably in the range of 10. −8 ~10 −4 s −1The stress sensitivity index is preferably in the range of 2.0 to 3.5.
[0077] In actual construction, when the coal face advances slowly, the floor rock mass has more time to undergo rheological deformation and plastic damage, allowing the damaged zone to develop fully and potentially leading to deeper damage. Conversely, when the coal face advances rapidly, stress changes quickly, the rock mass response is closer to elasticity, and the plastic zone is not fully developed, potentially leading to shallower damage. By using the damage function of the coal seam floor rock mass as the coal face advances, relevant information during construction can be quantified, providing a more comprehensive consideration and effectively improving the reliability of the analysis results.
[0078] S520: Based on the damage function and the initial cohesion of the rock mass at the bottom of the coal seam, the cohesive damage evolution information of the bottom of the coal seam is obtained.
[0079] Information on cohesive damage evolution is : ;in, It is the initial cohesion of the rock mass at the bottom of the coal seam.
[0080] S530: Based on the damage function and the initial internal friction angle of the rock mass at the bottom of the coal seam, the internal friction angle damage evolution information of the bottom of the coal seam is obtained.
[0081] Internal friction angle damage evolution information is : ; ; The initial internal friction angle of the rock mass at the bottom of the coal seam.
[0082] S540, based on the cohesive damage evolution information, internal friction angle damage evolution information, maximum principal stress, and minimum principal stress, determines the risk failure boundary corresponding to the coal seam floor.
[0083] Specifically, all failure points in the target mining area that meet the preset conditions are obtained, and the line connecting all failure points forms the risk failure boundary corresponding to the coal seam floor.
[0084] The preset conditions are: .
[0085] S550 uses the maximum depth value within the risk breach boundary as the predicted breach depth at the current moment.
[0086] Alternatively, all destruction points within the risk destruction boundary can be used as the predicted change information corresponding to the predicted destruction depth at the current moment, i.e., future destruction information that changes over time.
[0087] The main function of the backfill is to replace the mined coal and support the overlying strata, thereby reducing strata movement and the supporting pressure transmitted to the floor. The denser and stronger the backfill, the better the supporting effect, and the closer the supporting pressure on the floor is to the original stress state.
[0088] This method comprehensively considers effective stress, dynamic damage, and propulsion speed, and can more realistically reflect the spatiotemporal evolution of bottom plate failure, providing precise guidance for bottom plate water hazard prevention and control under different propulsion speeds.
[0089] This dynamic prediction method for the failure depth of the coal mine floor in backfilled mining significantly improves the accuracy, comprehensiveness, and engineering applicability of predictions through multi-dimensional parameter coupling, dynamic damage evolution analysis, and spatial-temporal dual-scale modeling. Specifically, it precisely couples the characteristics of the backfilling process, improving the accuracy of stress calculation. Traditional floor stress calculations are mostly based on models of unfilled goaf areas, neglecting the role of the backfill in sharing the overburden load. This scheme uses the preset backfilling rate as the core parameter, combined with the target coal seam mining thickness and geological parameters (such as rock mass elastic modulus, Poisson's ratio, etc.), to construct a targeted calculation model for the peak bearing stress in the backfilled stope. This design directly reflects the process characteristics of backfilling load reduction and roof control, avoiding the simplification error of equating the backfilled stope with the unfilled stope in traditional models. It makes the calculation of the peak bearing stress more consistent with the actual stress environment of backfilled mining, laying a precise mechanical foundation for subsequent stress distribution and failure prediction.
[0090] This proposed solution achieves the calculation of stress distribution across the entire three-dimensional space of the coal seam floor by obtaining vertical stress at any point (rather than a single feature point). Traditional methods often focus on stress below the working face or in a specific profile, easily neglecting stress differences in key areas such as the floor edges and structurally weak zones. This solution establishes a functional relationship between the peak bearing stress and the floor's spatial coordinates (strike, dip, and depth), outputting vertical stress values at different depths and horizontal positions. It comprehensively presents the floor stress field rather than stress points, providing global data support for subsequent analysis of damage risks in various areas and avoiding the one-sidedness of substituting local stress for the whole.
[0091] Rock mass failure is the result of the combined action of vertical and horizontal stresses. Especially in the foundation, horizontal stresses (such as tectonic stress and mining-induced lateral compressive stress) significantly influence the failure mode. This proposed scheme, based on vertical stress, further calculates horizontal stresses using geological parameters (such as the lateral pressure coefficient) and the influence of mining, forming a coupled vertical and horizontal dual-stress field model. Compared to the simplified analysis that focuses on vertical stress, this design better reflects the actual stress state of the rock mass, providing complete parameters for accurately deriving the maximum and minimum principal stresses, and avoiding calculation errors in principal stress differences caused by neglecting horizontal stress (such as underestimating the failure risk in areas dominated by tectonic stress).
[0092] This application introduces a damage evolution mechanism based on the coal face advance speed, cohesion, and internal friction angle, overcoming the limitations of traditional static prediction (based on the final stress state). In actual mining, the floor rock mass undergoes a dynamic process of stress concentration, damage accumulation, and strength deterioration as the working face advances: the advance speed affects the stress loading rate, thereby changing the damage development speed; cohesion (reflecting the rock mass bond strength) and internal friction angle (reflecting friction strength) gradually decrease as microcracks propagate. By establishing a quantitative relationship between principal stress difference and damage evolution (such as a strength parameter deterioration equation based on damage mechanics), the scheme can output the current failure depth in real time, dynamically reflecting the failure characteristics in the early stage (slow stress rise), middle stage (rapid damage accumulation), and final stage (stress stability) of mining, meeting the engineering needs for process risk early warning, rather than only providing the final failure result.
[0093] The depth of foundation failure is a core indicator for preventing water inrush (e.g., controlling the failure depth to not exceed the thickness of the impermeable layer) and optimizing support design (e.g., determining anchor bolt length). Through precise stress calculation, comprehensive distribution characterization, and dynamic damage analysis, the solution outputs a failure depth with both spatial and temporal dimensions: spatially, it can locate high-risk areas (e.g., stress concentration zones, structurally weak areas); temporally, it can predict the critical failure value at different stages of the process. This provides a scientific basis for on-site decision-making: for example, when the predicted failure depth at a certain stage approaches the critical thickness of the impermeable layer, filling parameters can be adjusted in a timely manner (e.g., increasing the filling thickness to reduce stress) or local support can be strengthened to avoid water inrush accidents; simultaneously, dynamic prediction can optimize the amount of filling material used (e.g., reducing the filling thickness in non-critical stages), thus reducing costs.
[0094] This application achieves a leap from static single-point estimation to dynamic global prediction of the depth of bottom plate failure through full-chain modeling of filling process parameters, global stress field, dual stress coupling, and dynamic damage evolution. Its core advantages lie in accuracy (considering filling characteristics), comprehensiveness (space + stress state), and dynamism (time + damage evolution), providing more scientific theoretical support and engineering guidance for the safe and efficient mining of coal mines with filling.
[0095] Traditional methods for assessing floor failure depth often rely on static empirical formulas or post-drilling inspections, which are time-lagging and cannot be updated synchronously with the advancement of the working face. This application introduces the advance speed as an explicit variable to couple and solve the support stress field, damage evolution field, and failure depth field. For the first time, it can output the "predicted failure depth h(t) at time t" before mining, thereby upgrading the floor safety assessment from post-drilling diagnosis to online prediction. This meets the rigid requirement of early detection, early warning, and early treatment of water inrush channels in backfill mining.
[0096] This application embeds the advance speed into the evolution equation of damage variables, realistically reflecting the time-dependent degradation effect of the floor rock mass under high ground stress and high shear rate, significantly improving the accuracy of floor water inrush risk assessment. All inputs in this application come from four types of conventional data already available in mining engineering: mining thickness, backfill thickness, geological profile, and advance speed. No additional expensive downhole monitoring equipment is required; minute-level calculations can be completed in the surface control room, resulting in low cost and facilitating rapid adoption in large-scale mines. By dynamically predicting the floor failure depth, it can accurately determine whether the water-conducting fracture zone touches strong aquifers such as Ordovician limestone and sandstone, thus providing the limit advance speed and minimum backfill rate for water-conserving mining. This allows the mine to maximize recovery rate while ensuring that the safe water inflow does not exceed the limit.
[0097] Secondly, this application discloses a method for early warning of sudden flooding, including: S10, Obtain the predicted depth of failure at the current moment according to the dynamic prediction method for the failure depth of the coal mine backfilling mining floor disclosed in the first aspect of this application; S20, obtain the effective normal stress acting on the fault plane (referring to the fault plane corresponding to the fault zone between the Ordovician limestone high-pressure water layer and the aquitard). (Refers to stress perpendicular to the fault plane); .
[0098] The angle between the fault plane and the horizontal plane. The water pressure of the Ordovician limestone layer is perpendicular to the top interface of the Ordovician limestone layer.
[0099] Based on the predicted damage depth, effective normal stress, and damage function, S30 indicates a potential risk of water inrush.
[0100] Specifically, if and It was determined that there was a potential for water inrush.
[0101] in, To predict the depth of damage, The tensile strength (Pa) corresponding to the fault plane (which can be measured by geological exploration methods). This refers to the shear stress corresponding to the fault plane (which can be measured using geological exploration methods). The cohesive force corresponding to the fault plane, The internal friction angle corresponding to the fault plane. The burial depth of the tip (or upper edge) of the water-conducting concealed fault (measured from the bottom of the mining area).
[0102] The essence of water inrush is that, under the disturbance of mining, the hidden water-conducting fault (or fracture) that was originally connected to the Ordovician limestone aquifer is activated, and the high-pressure water at its tip is conducted upward to the goaf along the newly formed dominant extension path (i.e., the floor failure zone) connected to it.
[0103] In this application, it is necessary to analyze both the path connectivity criterion and the fault activation criterion simultaneously. When both are satisfied, it indicates that there is a potential risk of water inrush.
[0104] By determining whether it is satisfied (Path connection judgment condition) is to determine whether a physical channel for the risk of water inrush is formed when the bottom plate failure zone caused by mining extends downward and intersects with the upper end of the hidden fault.
[0105] Fault activation criteria include extensional activation or shear activation; satisfying either one constitutes a fault activation criterion. When extensional activation is satisfied, it indicates that the fault plane is under tension and is highly susceptible to water diversion. When shear activation is satisfied, it indicates that the fault has undergone shear slip, significantly increasing its water conductivity, thus posing a risk of water inrush.
[0106] Furthermore, the application also includes: 1) Determine the stress exceedance factor based on the effective normal stress and the tensile strength, shear stress, cohesion, and internal friction angle corresponding to the fracture surface.
[0107] Stress exceedance factor is ; .
[0108] 2) Determine the corresponding water inrush early warning strategy based on the range of stress over-limit factor.
[0109] like This indicates that the fault is in a stable state, and the corresponding water inrush warning strategy is no warning, there is no risk of water inrush, and mining can continue.
[0110] like ,in, , The corresponding water inrush early warning strategy is to issue an early warning when the fault enters a risky state but has not reached the critical point, and to increase the preset filling rate to meet the requirements. According to satisfying The next step of mining and filling will be carried out at the corresponding preset filling rate.
[0111] like The corresponding water inrush early warning strategy is to issue an early warning when the fault reaches or exceeds the critical failure state, and to carry out water control in the target mining area.
[0112] This application establishes a dynamic prediction and early warning system covering the entire chain from "mining—backfilling—stress—damage—failure—water inrush" through the stress attenuation function of the backfill support, dynamic damage evolution mechanism, effective stress transformation of faults, and water inrush risk analysis. It has significant theoretical innovation and engineering application value.
[0113] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.
[0114] In this disclosure, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The block diagrams of devices, apparatuses, devices, and systems involved in this disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as "comprising," "including," "having," etc., are open-ended terms meaning "including but not limited to," and are used interchangeably with them. The terms "or" and "and" as used herein refer to the terms "and / or," and are used interchangeably with them unless the context clearly indicates otherwise. The term "such as" as used herein refers to the phrase "such as but not limited to," and is used interchangeably with it.
[0115] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.
[0116] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.
[0117] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.
[0118] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.
[0119] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.
Claims
1. A method for dynamically predicting the failure depth of the floor in coal mine backfilling mining, characterized in that, include: The peak support stress of the filling stope corresponding to the target coal seam is determined based on the target coal seam mining thickness, preset filling rate, and geological parameters of the target mining area; the target mining area includes the filling compaction zone, the coal body plastic zone, and the coal body elastic zone; Based on the peak value of the supporting stress in the filling stope, obtain the vertical stress at any point on the coal seam floor of the target mining area. Based on the vertical stress at any point on the coal seam floor of the target mining area, determine the horizontal stress at any point on the coal seam floor of the target mining area; Based on the vertical and horizontal stresses at any point on the coal seam floor of the target mining area, determine the maximum and minimum principal stresses of the target mining area. Based on the maximum principal stress, the minimum principal stress, and the advance speed of the coal mining face, the cohesive damage evolution information and internal friction angle damage evolution information of the coal seam floor are obtained, and the predicted damage depth corresponding to the current moment is determined.
2. The method for dynamically predicting the failure depth of the coal mine backfill mining floor according to claim 1, characterized in that, The step of determining the peak support stress of the backfilled stope corresponding to the target coal seam based on the target coal seam mining thickness, preset backfilling ratio, and geological parameters of the target mining area includes: Obtain the peak value of the advance support pressure corresponding to the mining face in the mined but unfilled area with similar geological conditions to the target coal seam; Based on the peak value of the advance support pressure, the target coal seam mining thickness, and the preset filling rate, determine the maximum support pressure of an area with similar geological conditions to the target coal seam when it has been mined but not filled. The maximum support pressure is A: ;in, The peak value of the advanced support pressure. The target coal seam mining thickness, For reference mining height; Obtain the maximum reduction in support pressure corresponding to a mined and fully compacted coal seam with similar geological conditions to the target coal seam. The maximum support pressure reduction corresponding to the target mining area is determined based on the maximum support pressure reduction, the target coal seam mining thickness, and the preset filling rate. The reduction in maximum support pressure corresponding to the target mining area is: : ;in, The reduction in maximum support pressure corresponding to a fully compacted and backfilled coal seam with similar geological conditions to the target coal seam; Obtain the basic efficiency coefficient of an area with similar geological conditions to the target coal seam when it is filled with pure gangue without cement; Based on the basic efficiency coefficient, cementing slurry contribution coefficient, and cementing material content percentage, determine the filling material parameters corresponding to the target coal seam; The parameters of the filler material are as follows: : ; 0 < ≤0.5; where, This refers to the basic efficiency coefficient. The contribution coefficient of the cementitious slurry. This represents the percentage of cementitious material added. Based on the maximum support pressure, the reduction in the maximum support pressure corresponding to the target mining area, and the filling material parameters, the peak support stress of the backfilled mining area corresponding to the target coal seam is obtained. The peak bearing stress in the backfilled stope corresponding to the target coal seam is : , The preset filling rate for the target coal seam.
3. The method for dynamically predicting the depth of failure of the coal mine backfill mining floor as described in claim 2, characterized in that, The step of obtaining the vertical stress at any point on the coal seam floor of the target mining area based on the peak value of the supporting stress in the filled mining area includes: Based on the target bottom density and the location of the coal seam floor, determine the initial vertical stress at any point on the coal seam floor when the target coal seam is not mined. Based on the peak value of the supporting stress in the filling stope, the vertical stress increments of the filling compaction zone, the coal body plastic zone, and the coal body elastic zone at any point on the bottom of the coal seam are obtained and recorded as the first vertical stress increment, the second vertical stress increment, and the third vertical stress increment, respectively. Based on the first vertical stress increment, the second vertical stress increment, and the third vertical stress increment, the mining-induced vertical stress increment at any point on the coal seam floor of the target mining area is obtained. Based on the initial vertical stress at any point on the coal seam floor when the target coal seam is not mined, and the incremental vertical stress at any point on the coal seam floor in the target mining area, the vertical stress at any point on the coal seam floor in the target mining area is obtained.
4. The method for dynamically predicting the depth of failure of the coal mine backfill mining floor as described in claim 3, characterized in that, The method for obtaining the first vertical stress increment includes: The stress corresponding to the filling and compaction zone is determined based on the peak support stress of the filling stope. Based on the thickness of the aquitard corresponding to the target mining area and the vertical distance between the Ordovician limestone high-pressure aquitard and the bottom of the aquitard, determine the first included angle corresponding to any point on the bottom plate of the coal seam in the filling and compaction zone; The first boundary angle corresponding to any point on the bottom of the coal seam in the filled and compacted zone is determined based on the lateral distance from the boundary of the fully filled and compacted zone to the coal face, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the high-pressure aquitard of the Ordovician limestone and the bottom of the aquitard. The first vertical stress increment is determined based on the stress corresponding to the filling and compaction zone, the first included angle, and the first boundary angle.
5. The method for dynamically predicting the failure depth of the coal mine backfill mining floor according to claim 4, characterized in that, The method for obtaining the second vertical stress increment includes: The stress corresponding to the plastic zone of the coal body is determined based on the peak support stress of the filling stope. The stress corresponding to the plastic zone of the coal body is: : ; ; This is the proportionality coefficient corresponding to the plastic zone of the coal body; Based on the thickness of the aquitard corresponding to the target mining area, the vertical distance between the high-pressure aquitard layer of Ordovician limestone and the bottom of the aquitard, determine the second included angle corresponding to any point on the bottom plate of the coal seam in the plastic zone of the coal body; The second included angle is : , Let be the lateral coordinate value of any point on the bottom plate of the coal seam located in the plastic zone of the coal body. Here is the vertical coordinate value of any point on the bottom portion of the coal seam located in the plastic zone of the coal body. The thickness of the aquitard corresponding to the target mining area. It is the vertical distance between the bottom of the high-pressure water-bearing layer and the waterproof layer of Ordovician limestone. The second boundary angle corresponding to any point on the bottom plate of the coal seam in the plastic zone of the coal body is determined based on the lateral length of the boundary of the coal body plastic zone, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the high-pressure aquitard of the Ordovician limestone and the bottom of the aquitard. The second boundary angle is : ; The transverse length of the boundary of the plastic zone of the coal body; The second vertical stress increment is determined based on the stress corresponding to the plastic zone of the coal body, the second included angle, and the second boundary angle; The second vertical stress increment is : 。 6. The method for dynamically predicting the failure depth of the coal mine backfill mining floor according to claim 5, characterized in that, The method for obtaining the third vertical stress increment includes: The stress corresponding to the elastic zone of the coal body is determined based on the peak support stress of the filling stope. The stress corresponding to the elastic zone of the coal body is : ; Based on the thickness of the aquitard corresponding to the target mining area, the vertical distance between the high-pressure aquitard layer of Ordovician limestone and the bottom of the aquitard, determine the third included angle corresponding to any point on the bottom plate of the coal seam in the elastic zone of the coal body; The third included angle is : , This represents the lateral coordinate value of any point on the bottom plate of the coal seam located in the elastic zone of the coal body. The vertical coordinate value is the value of any point on the bottom plate of the coal seam located in the elastic zone of the coal body. Based on the transverse length of the elastic zone of the coal body, the thickness of the aquitard corresponding to the target mining area, and the vertical distance between the Ordovician limestone high-pressure water layer and the bottom of the aquitard, determine the third boundary angle corresponding to any point on the bottom plate of the coal seam in the elastic zone of the coal body. The third boundary angle is : ; The transverse length of the elastic zone of the coal body; The third vertical stress increment is determined based on the stress corresponding to the elastic zone of the coal body, the third included angle, and the third boundary angle. The third vertical stress increment is : 。 7. The method for dynamically predicting the depth of failure of the coal mine backfill mining floor as described in claim 3, characterized in that, The step of determining the horizontal stress at any point on the coal seam floor of the target mining area based on the vertical stress at any point on the coal seam floor includes: Based on the vertical stress increment caused by mining at any point on the coal seam floor of the target mining area, determine the horizontal stress increment caused by mining at any point on the coal seam floor of the target mining area. The incremental horizontal stress caused by mining at any point on the coal seam floor in the target mining area is: : , Poisson's ratio; The horizontal stress at any point on the coal seam floor of the target mining area is determined based on the vertical stress at any point on the coal seam floor of the target mining area and the incremental horizontal stress caused by mining at any point on the coal seam floor of the target mining area. The horizontal stress at any point on the coal seam floor in the target mining area is: : ; This is the lateral pressure coefficient.
8. The method for dynamically predicting the failure depth of the coal mine backfill mining floor according to claim 4, characterized in that, The process of obtaining cohesive damage evolution information and internal friction angle damage evolution information of the coal seam floor based on the maximum principal stress, the minimum principal stress, and the advance speed of the coal mining face, and determining the predicted failure depth at the current moment, includes: Based on the maximum principal stress, the minimum principal stress, and the advance speed of the coal mining face, obtain the damage function of the coal seam floor rock mass as the advance speed of the coal mining face changes; Based on the damage function and the initial cohesion of the rock mass at the bottom of the coal seam, the cohesion damage evolution information of the bottom of the coal seam is obtained. Based on the damage function and the initial internal friction angle of the rock mass at the bottom of the coal seam, the internal friction angle damage evolution information of the bottom of the coal seam is obtained. Based on the cohesive damage evolution information, the internal friction angle damage evolution information, the maximum principal stress, and the minimum principal stress, the risk failure boundary corresponding to the coal seam floor is determined. The maximum depth value within the risk destruction boundary is taken as the predicted destruction depth at the current moment.
9. The method for dynamically predicting the depth of failure of the coal mine backfill mining floor as described in claim 8, characterized in that, The step of determining the risk damage boundary corresponding to the coal seam floor based on the cohesive damage evolution information, the internal friction angle damage evolution information, the maximum principal stress, and the minimum principal stress includes: obtaining all damage points in the target mining area that meet preset conditions, and connecting all the damage points to form the risk damage boundary corresponding to the coal seam floor. The preset conditions are: ; ； ； ； ； ； in, The damage function is... The damage acceleration index, As the damage rate baseline, The stress sensitivity index, To determine the advance speed of the coal mining face, This refers to the cohesive damage evolution information. It is the initial cohesion of the rock mass at the bottom of the coal seam. This refers to the damage evolution information of the internal friction angle. The initial internal friction angle of the rock mass at the bottom of the coal seam. The maximum principal stress of the target mining area, The minimum principal stress of the target mining area is given.
10. A method for early warning of sudden flooding, characterized in that, include: The dynamic prediction method for the failure depth of the coal mine backfill mining floor according to any one of claims 1-9 obtains the predicted failure depth at the current moment; Obtain the effective normal stress acting on the fault plane; Based on the predicted damage depth and the effective normal stress, a potential risk of water inrush is identified.