A method for intelligently identifying and enhancing effective barrier under minefield aquifer protection

Abstract

The application provides a kind of intelligent discrimination and enhancement method of effective barrier layer under aquifer protection in mining area, and belongs to the technical field of water-preserved mining.The method obtains geological parameters and coal rock mass physical and mechanical parameters of multiple experimental mines, uses 3DEC numerical simulation to simulate the fracture morphology of overburden rock after mining, establishes a water resource seepage model combined with COMSOL Multiphysics software, and calculates the water resource intrusion depth.Then, the relevant parameters are taken as input, the water resource intrusion depth is taken as output, the SVM model is trained to build an intelligent discrimination model of barrier layer water resource seepage, and then the water resource intrusion depth is predicted and the effective barrier layer thickness is calculated combined with the safety factor.The effective barrier layer is discriminated and processed according to different conditions.The application uses the above-mentioned intelligent discrimination and enhancement method of effective barrier layer under aquifer protection in mining area, discriminates and enhances the water-resisting capacity of the effective barrier layer, and realizes the protection of water resources in mining area.

Description

Technical Field

[0001] This invention relates to the field of water-conserving mining technology, and in particular to a method for intelligent identification and enhancement of effective barrier layers under aquifer protection in mining areas. Background Technology

[0002] Coal mining causes environmental problems such as surface subsidence and water loss, with water loss due to aquifer damage being particularly prominent. Coal mining causes upward and downward seepage fractures in the overlying strata under gravity, destroying the natural barrier layer between the coal seam and the aquifer. When the fractures or seepage penetrate the barrier layer, aquifer water will flood into the mined-out area, causing surface vegetation to wither and die, seriously threatening the ecological balance and residents' lives. To address this problem, intelligent identification technology is used to assess the water-impermeable performance of the barrier layer, and artificial thickening measures are implemented to effectively protect groundwater resources and ensure safe production in the mining area.

[0003] Chinese invention patent CN114673532A discloses a method for reducing settlement by grouting the entire fracture zone to prevent roof water infiltration. This method involves drilling multiple anchoring shafts from the ground to the water-resistant key layer before mining, constructing rock anchoring pits in the overlying strata above the water-resistant key layer, and injecting anchoring grout into the grouting pipeline under pressure to form a full-length anchoring along the burial depth of the water-resistant key layer. All anchoring shafts together form an anchoring shaft group, which creates a group anchoring effect on the overlying strata above the water-resistant key layer, thereby reducing the occurrence of roof water infiltration accidents.

[0004] Patent CN115791390A discloses a laboratory simulation and testing method for the reconstruction effect of a waterproof layer. The method includes: on-site surveying to understand the spatial characteristics of the waterproof layer; placing a standard rock sample of the waterproof layer inside a mold and testing its compressive strength; injecting a waterproof cementitious slurry into the mold to simulate the waterproof layer reconstruction process; after curing and demolding, testing the compressive strength of the reconstructed waterproof layer; and calculating the compressive strength of the reconstructed rock sample according to the compressive strength conversion coefficient between the standard sample and the mold dimensions, thereby achieving laboratory simulation and testing of the waterproof layer reconstruction effect. This method reflects the on-site waterproof layer reconstruction project effect to a certain extent.

[0005] The above patents have the following problems: Patent CN114673532A only proposes a grouting method and does not consider the damage to the effective barrier layer caused by the development of upward and downward seepage fractures and water seepage during mining. Patent CN115791390A has relatively ideal laboratory conditions and cannot fully simulate the complex geological conditions, stress state, and groundwater flow in the field. Therefore, a new method is urgently needed to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent method for identifying and enhancing the effective barrier layer under the protection of aquifers in mining areas. By identifying and enhancing the water-blocking capacity of the effective barrier layer, the protection of water resources in mining areas can be achieved.

[0007] To achieve the above objectives, this invention provides a method for intelligent identification and enhancement of effective barrier layers under aquifer protection in mining areas, comprising the following steps:

[0008] Step S1: Obtain geological parameters and physical and mechanical parameters of coal and rock mass from multiple experimental mines; among which, the geological parameters include: working face height M, aquifer thickness h. 水 The thickness H of the overlying strata above the coal seam, the distance H1 from the overlying aquifer to the coal seam, rock mass samples, and the permeability coefficient of the overlying strata obtained by porosimetry testing. And porosity m; physical and mechanical parameters of coal and rock mass include: bulk modulus K, shear modulus G, tensile strength R, cohesion C, internal friction angle θ and density ρ of each coal and rock mass obtained through rock mechanics tests;

[0009] Step S2: Based on the working face mining height M, overburden thickness H, and physical and mechanical parameters of coal and rock mass obtained in step S1, the development morphology of overburden fractures after mining is simulated using 3DEC numerical simulation, including: upward fracture development height h1, downward fracture development depth h2, and downward fracture tensor d2. The thickness of the unaffected layer is calculated by h = H - h1 - h2.

[0010] Determine if h exists (i.e., if h is greater than 0), and retain data where h > 0.

[0011] When h is greater than 0, the barrier layer is not penetrated by the cracks, and the water in the overlying aquifer may be lost due to seepage. This set of data is retained.

[0012] When h equals 0, the barrier layer is penetrated by the fracture, and the water resources in the overlying aquifer can be lost through the fracture channel, so this set of data is discarded.

[0013] Select the working face mining height M and aquifer thickness h 水 Thickness H of overlying strata above the coal seam, distance H1 from the overlying aquifer to the coal seam, and permeability coefficient of the overlying strata. Porosity m, upward fracture development height h1, and downward fracture development depth h2 are used as sample data 1;

[0014] Step S3: Based on the aquifer thickness h obtained in step S1 水 Permeability coefficient of overlying strata With porosity m and fracture development morphology obtained in step S2, a water resource seepage model after full mining damage was established using COMSOL Multiphysics numerical simulation software to obtain the depth q1 of water resources intruding into the rock strata, which was used as sample data 2.

[0015] The seepage results can be categorized into two scenarios:

[0016] 1. When the seepage boundary does not reach the upward fracture, i.e., 0 < q1 < h, that is, no water loss occurs, and q1 is the depth of water intrusion.

[0017] 2. When the seepage boundary comes into contact with the upward fracture, if q1 ≥ h, water seepage occurs and the accurate value of q1 cannot be determined. For this type of data, the height is reduced by M1 while other parameters remain unchanged. The corrected value of q1' is then substituted into step S2 to obtain the corrected value of q1'.

[0018] Step S4: Construct an intelligent discrimination model for water resource seepage in the barrier layer using the support vector machine algorithm; train the intelligent discrimination model for water resource seepage using sample data 1 as the model input and sample data 2 as the model output.

[0019] Step S5: After model training is complete, the predicted working face mining height M and aquifer thickness h are set. 水 Thickness H of overlying strata above the coal seam, distance H1 from the overlying aquifer to the coal seam, and permeability coefficient of the overlying strata. Porosity m, upward fracture development height h1, and downward fracture development depth h2 are input into the intelligent water resource seepage discrimination model of the barrier layer to predict the depth q2 of water resources intruding into the rock strata. Combined with the safety factor λ, the effective barrier layer thickness Q is calculated.

[0020]

[0021] Step S6: Determine the water-resistant capability based on the effective barrier layer thickness Q;

[0022] When H1-h1-h2-q2≤0, this is the seepage water loss state. The seepage water loss is that the upward and downward seepage fractures have not penetrated the barrier layer. Water resources in the overlying aquifer enter the upward fractures along the downward seepage fractures under the action of seepage, causing slow seepage and resulting in the barrier layer losing its water-proofing ability. Take Q=0.

[0023] When H1-h1-h2-q2>0, this is the effective water-tight state. The effective water-tight state is characterized by the upward and downward infiltration fractures not penetrating the barrier layer, and water resources in the downward infiltration fractures not invading the upward infiltration fractures under seepage. Therefore, the barrier layer still possesses water-tightness.

[0024] Step S7: Calculate the protective layer thickness P according to the "Specifications for Coal Pillar Retention and Coal Mining in Buildings, Water Bodies, Railways and Main Shafts";

[0025] Step S8, Effective Barrier Layer Thickening Method: The effective barrier layer thickening method consists of damage classification, on-site monitoring, and treatment measures. The overlying barrier layer is classified and corresponding measures are taken to ensure the safe mining of coal resources and prevent the loss of water resources from the overlying aquifer.

[0026] Damage is classified as follows: by comparing the effective thickness Q calculated from the analysis with the protective layer thickness P required for water-retaining coal mining as specified in the regulations, the barrier layer is divided into three types: intact and difficult to damage, potentially damaged, and easily damaged and permeable. To ensure the accuracy and reliability of the classification results, an error threshold x is set based on relevant data from adjacent mining areas during the classification process.

[0027] When Q > P + x, the barrier layer is determined to be of the intact and difficult-to-damage type, and the effective barrier layer thickness is greater than the safe thickness required for water-retaining mining calculated by the regulations. The conditions for safe mining of the working face are met, and normal mining can proceed. Periodic on-site monitoring will be conducted during the mining process until safe mining of the working face is completed.

[0028] When Px≤Q≤P+x, the barrier layer is classified as potentially damaging. Since the effective barrier layer thickness is less than the safe thickness required for water-retaining mining calculated in the regulations, on-site monitoring is conducted concurrently with mining. If an increase in mine drainage is detected, production is immediately halted, and local thickening measures are implemented for the overlying water-retaining layer. After the thickening measures are implemented, the relationship between the effective barrier layer thickness Q and the protective layer thickness P is dynamically monitored until safe mining at the working face is completed.

[0029] When Q < Px, the barrier layer is determined to be vulnerable and permeable, and the effective barrier layer thickness is much smaller than the safe thickness required for water-retaining mining calculated in the regulations, thus failing to meet the conditions for safe mining of the working face. A dual approach of local thickening and source treatment is adopted. After the local thickening measures are completed, source treatment measures are implemented, and the relationship between the effective barrier layer thickness Q and the protective layer thickness P is monitored in real time until safe mining of the working face is completed.

[0030] The treatment measures include source treatment and local thickening.

[0031] Source treatment refers to measures to change the coal resource recovery method, thereby reducing the development height of upward fractures and the development depth of downward fractures, and further increasing the thickness of the effective barrier layer. Recovery methods include backfilling mining and height-limited mining.

[0032] Among them, if D≤M, the green mining technology of backfilling mining, which involves backfilling materials into the goaf to support the roof, reduce surface subsidence, improve resource recovery rate and reduce environmental impact, can effectively control roof pressure, reduce the development of cracks, and thus thicken the effective barrier layer.

[0033] If D > M, then height-restricted mining is adopted. Height-restricted mining is a mining method that controls the impact of mining on overlying strata and surface deformation by limiting the mining height of the coal seam. Its core objective is to suppress the development of water-conducting fracture zones, avoid damaging the structure of the overlying aquifer, achieve water-conserving coal mining, and further thicken the effective barrier layer.

[0034] D represents the minimum extendable height of the hydraulic support currently in use in coal mining.

[0035] The localized treatment involves grouting technology applied to the lower part of the aquifer. The specific implementation method is as follows: grouting holes are extended to the lower part of the target aquifer through ground drilling, and grout is injected to reduce permeability and increase the effective thickness of the barrier layer.

[0036] If the infiltration fracture tensor d2 < L, it is a closed microfracture. In this case, a high-permeability resin grouting method is adopted. The high-permeability resin grouting method injects malissa, a two-component synthetic polymer material (polyimide resin) composed of resin and catalyst. It has the characteristics of low viscosity, high expansion rate, strong adhesion and fast reaction. The injection of this substance fills the pores and forms a dense structure, which significantly reduces the permeability and prevents water infiltration. This effectively thickens the barrier layer.

[0037] If the infiltration fracture tensor d2 > L, then it is a wide fracture. In this case, the composite aggregate grouting method is adopted. The composite aggregate grouting method refers to a grout made by mixing cement as the main component with other materials (such as water, fly ash, clay, water glass, etc.). Depending on the size of the opening, fly ash, gangue and other materials are added to achieve efficient sealing of large fractures and thicken the effective barrier layer.

[0038] L represents the crack width specified in the "Code for Construction and Acceptance of Building Materials and Mining Engineering" for the selection of grout types.

[0039] The on-site monitoring included: aquifer water level monitoring, seepage distance monitoring in the barrier layer, and monitoring of the height of upward-extending fractures and the depth and width of downward-extending fractures. Among these, transient electromagnetic methods were used for aquifer water level monitoring; isotope tracing technology was used for seepage distance monitoring in the barrier layer; borehole inspection was used for fracture development depth monitoring, and ground-penetrating radar scanning was used for fracture development width monitoring.

[0040] Therefore, the present invention employs the above-mentioned intelligent identification and enhancement method for effective barrier layers under aquifer protection in mining areas, and the beneficial technical effects are as follows:

[0041] (1) By acquiring the physical and mechanical parameters of the coal and rock mass in the mine and related sample data, the morphology of the overlying fractures after mining was simulated using 3DEC numerical simulation, and a water resource seepage model was established using COMSOL Multiphysics software. This model was then used to train an SVM model to construct an intelligent discrimination model for water resource seepage in the barrier layer. This model can accurately predict the depth of water intrusion based on the relevant parameters of the mine to be predicted, and calculate the effective barrier layer thickness based on the safety factor. Then, based on the comparison between the effective barrier layer thickness and the protective layer thickness, the barrier layer is divided into three types: intact and difficult to damage, potentially damaged, and easily damaged and permeable. This enables accurate assessment and classification of the water-blocking capacity of the barrier layer in the mining area, providing a scientific basis for subsequent targeted enhancement measures.

[0042] (2) The intelligent discrimination system built with the SVM model can quickly and accurately determine the water-proof status of the barrier layer, i.e., whether it is in a seepage-induced water-proof state or an effective water-proof state. When there is a risk of seepage-induced water loss in the barrier layer, an early warning signal is issued in a timely manner to remind relevant personnel to take corresponding measures, effectively avoiding the large-scale loss of water resources and potential ecological and safety hazards caused by the failure of the barrier layer. Compared with the traditional discrimination method that relies on manual experience or a single monitoring method, it is more intelligent, efficient and accurate.

[0043] (3) Corresponding thickening methods were developed for barrier layers with different damage classifications. For example, for intact and difficult-to-damage barrier layers, normal mining and periodic monitoring are sufficient; for potentially damaged barrier layers, monitoring is carried out while mining, and local treatment is implemented in the lower part of the aquifer when drainage increases; for vulnerable and permeable barrier layers, source treatment and local treatment are implemented simultaneously. Source treatment is carried out by selecting backfill mining or height-restricted mining according to the actual situation, and local treatment is carried out by using high-permeability resin grouting method or composite aggregate grouting method according to the size of the infiltration fracture tensor. This realizes the customized design of barrier layer thickening scheme, which can effectively improve the water-proof performance of barrier layers, reduce water resource loss during coal mining, ensure safe production and ecological environment stability in mining areas, overcome the problems of single and insufficient targeting of existing thickening methods, and significantly improve the thickening effect and water resource protection efficiency. Attached Figure Description

[0044] Figure 1 This is a flowchart of an intelligent identification and enhancement method for effective barrier layers under aquifer protection in mining areas, according to the present invention.

[0045] Figure 2 A complete and difficult-to-destroy overlying rock model diagram;

[0046] Figure 3 A model diagram of the overlying rock strata that may be damaged;

[0047] Figure 4 This is a model diagram of the overlying rock strata, which are easily damaged and permeable. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0050] Example 1

[0051] Figure 1 The flowchart illustrates a method for intelligent identification and enhancement of effective barrier layers under aquifer protection in mining areas, specifically including the following steps:

[0052] Step S1: Obtain geological parameters and coal-rock mass physical and mechanical parameters from 100 experimental mines in adjacent areas with similar geological conditions. The coal-rock mass physical and mechanical parameters include the bulk modulus K, shear modulus G, tensile strength R, cohesion C, internal friction angle θ, and density ρ of each coal-rock mass obtained through rock mechanics tests (see Table 1 for details). Geological parameters include the working face height M and the aquifer thickness h. 水 The thickness H of the overlying strata above the coal seam, the distance H1 from the overlying aquifer to the coal seam, rock mass samples, and the permeability coefficient of the overlying strata obtained by porosimetry testing. For details on porosity (m), please refer to Tables 2, 3 and 4.

[0053] Table 1 Physical and Mechanical Parameters of Coal and Rock Mass

[0054]

[0055]

[0056] Table 2. Permeability and Porosity Parameters of Overlying Rock Layers

[0057] Rock strata number Lithology <![CDATA[Permeability coefficient (m·s -1 )]]> Porosity 1 clay <![CDATA[5.37×10 -8 ]]> 0.226 2 sandstone <![CDATA[1.38×10 -5 ]]> 0.145 3 siltstone <![CDATA[4.71×10 -7 ]]> 0.215 4 medium sandstone <![CDATA[6.23×10 -7 ]]> 0.268 5 mudstone <![CDATA[2.93×10 -4 ]]> 0.362 6 coal seam <![CDATA[3.07×10 -4 ]]> 0.0037

[0058] Table 3. Relevant parameters such as overall thickness, spacing, and mining height of the overburden.

[0059]

[0060]

[0061] Step S2: Based on the working face height M, overburden thickness H, and physical and mechanical parameters of coal and rock mass obtained in step S1, the development morphology of overburden fractures after mining is simulated using 3DEC numerical simulation, including: the height of upward fracture development h1, the depth of downward fracture development h2, and the tensor of downward fracture d2. The thickness of the unaffected layer is calculated by h = H - h1 - h2.

[0062] Determine if h exists, i.e., whether h is greater than 0.

[0063] When h is greater than 0, the barrier layer is not penetrated by the cracks, and the water in the overlying aquifer may be lost due to seepage. This set of data is retained.

[0064] When h equals 0, the barrier layer is penetrated by the fracture, and the water resources in the overlying aquifer can be lost through the fracture channel, so this set of data is discarded.

[0065] Retain data where h > 0. See Table 4 for details.

[0066] Table 4. Fracture morphology and barrier layer thickness after full mining of the overlying strata.

[0067]

[0068]

[0069] In the above-mentioned locations 16, 17, 22, 34, 40, 43, 49, 50, 55, 58, 61, 71, 77, and 78, the overlying rock layers are perforated by fissures, and water is lost along the fissures; for the remaining locations, h is greater than 0, and the overlying rock layers are not perforated by fissures, so seepage and water loss may occur.

[0070] Select the working face mining height M and aquifer thickness h 水 Thickness H of overlying strata above the coal seam, distance H1 from the overlying aquifer to the coal seam, and permeability coefficient of the overlying strata. Porosity m, upward fracture development height h1, and downward fracture development depth h2 are used as sample data 1.

[0071] Step S3: Based on the aquifer thickness h obtained in step S1 水 Permeability coefficient of overlying strata Based on the porosity m and the fracture development morphology obtained in step S2, a water resource seepage model after full mining damage was established using COMSOL Multiphysics numerical simulation software. The depth q1 of water resources intruding into the rock strata was obtained as sample data 2, as detailed in Table 5.

[0072] Table 5 Results of the Water Resources Seepage Model

[0073]

[0074]

[0075]

[0076] Step S4: Construct an intelligent discrimination model for water resource seepage in the barrier layer using the support vector machine (SVM) algorithm; train the intelligent discrimination model for water resource seepage using sample data 1 as the model input and sample data 2 as the model output.

[0077] When constructing an intelligent prediction model for seepage in a barrier layer using the Support Vector Machine (SVM) algorithm, the hyperparameters of the SVM model are adjusted, including the regularization parameter, the degree of the polynomial kernel, and the width of the RBF kernel. At the same time, the maximum number of iterations is set, and the training sample data is substituted into the SVM model for sample training to obtain the SVM model.

[0078] Step S5: Select an example mine other than the sample mines mentioned above and obtain relevant parameters, as detailed in Table 6. The distance H1 from the aquifer to the coal seam is 157.03m, and the overburden permeability coefficient φ and porosity m are shown in Table 7.

[0079] Table 6. Relevant Parameters of Example Mines

[0080]

[0081] Table 7. Permeability and Porosity Parameters of Overlying Rock Formations in Example Mines

[0082] Rock strata number Lithology <![CDATA[Permeability coefficient (m·s -1 )]]> Porosity 1 clay <![CDATA[5.37×10 -8 ]]> 0.226 2 sandstone <![CDATA[1.38×10 -5 ]]> 0.145 3 siltstone <![CDATA[4.71×10 -7 ]]> 0.215 4 medium sandstone <![CDATA[6.23×10 -7 ]]> 0.268 5 mudstone <![CDATA[2.93×10 -4 ]]> 0.362 6 coal seam <![CDATA[3.07×10 -4 ]]> 0.0037

[0083] Numerical simulation using 3DEC revealed that the height of the upward fractures was 110m, the depth of the downward fractures was 35m, the width of the upward fractures was 3cm, and the width of the downward fractures was 1.3mm.

[0084] Substituting the aforementioned parameters, overburden permeability coefficient, porosity, and the height of the upward fracture (110m) and the depth of the downward fracture (7.5m) into the trained intelligent prediction model for the seepage distance of the barrier layer, the water intrusion depth was found to be 8.4m.

[0085] Based on the development of overlying rock fissures in the adjacent mining areas, 1.3 was selected as the safety factor for calculating the effective barrier thickness, and the effective barrier Q was calculated to be 11.13m.

[0086] Step S6: Determining the presence of a barrier layer under seepage:

[0087] Calculate H1-h1-h2-q2=137.03-110-7.5-8.4=11.13, 11.13>0, that is, the barrier layer exists, and it is in an effective water-proof state.

[0088] Step S7: Calculation of the required protective layer thickness for water-retaining coal mining:

[0089] Based on the mining height M of the working face and the lithology of the overlying strata above the coal seam, the required protective layer thickness P for water-retaining mining is calculated using the calculation formula for the thickness of the waterproof safety coal (rock) pillar protective layer in the "Specifications for the Retention of Coal Pillars in Buildings, Water Bodies, Railways and Main Shafts and Coal Mining".

[0090] In the example, the protective layer thickness in the production mine area is P = 3M = 10.8m;

[0091] Step S8: Effective barrier layer thickening method.

[0092] like Figure 2 As shown, when Q > P + x, the effective barrier layer is determined to be intact and difficult to damage, and normal mining and periodic monitoring are carried out; x represents the preset threshold.

[0093] like Figure 3 As shown, when Px≤Q≤P+x, the effective barrier layer is determined to be of the potential damage type. On-site monitoring is carried out while mining is underway, and local treatment is implemented in the lower part of the aquifer when the drainage volume increases.

[0094] like Figure 4 As shown, when Q < Px, the effective barrier layer is determined to be vulnerable and easily permeable, and source treatment and local treatment are implemented simultaneously.

[0095] Based on relevant data from adjacent mining areas, 5m was selected as the error threshold, and a comparative analysis was conducted.

[0096] Table 8 shows the effective barrier layer thickness, protective layer thickness, and barrier layer type for example production mines.

[0097] Table 8. Effective barrier layer thickness, protective layer thickness, and barrier layer type in example production mines.

[0098] Serial Number Q P P+5 P-5 Effective barrier layer type 1 11.13 10.8 15.8 5.8 Potential damage category

[0099] In summary, the effective barrier layer of the above-mentioned mine is classified as potentially damaged, and the width of the seepage fractures is 1.3 mm. According to the fracture width specified in the "Code for Construction and Acceptance of Building Materials and Mining Engineering," this mine has wide, open fractures. Therefore, a composite aggregate grouting method is adopted. This method uses cement as the main component, mixed with fly ash to create a grout that effectively seals the fractures and locally thickens the overlying barrier layer. Mining will commence only after the thickening measures are implemented. During mining, the effective barrier layer thickness Q will be dynamically adjusted based on monitoring results until safe mining of the working face is completed.

[0100] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0101] Therefore, the present invention adopts the above-mentioned intelligent identification and enhancement method for effective barrier layer under aquifer protection in mining areas, and realizes the protection of water resources in mining areas by identifying and enhancing the water-blocking capacity of the effective barrier layer.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for intelligent identification and enhancement of effective barrier layers under aquifer protection in mining areas, characterized in that, Includes the following steps: Step S1: Obtain geological parameters and physical and mechanical parameters of coal and rock mass from multiple experimental mines; among which, the geological parameters include: working face height M, aquifer thickness h. 水 The thickness H of the overlying strata above the coal seam, the distance H1 from the overlying aquifer to the coal seam, rock mass samples, and the permeability coefficient of the overlying strata obtained by porosimetry testing. And porosity m; physical and mechanical parameters of coal and rock mass include: bulk modulus K, shear modulus G, tensile strength R, cohesion C, internal friction angle θ and density ρ of each coal and rock mass obtained through rock mechanics tests; Step S2: Based on the working face mining height M, overburden thickness H, and physical and mechanical parameters of coal and rock mass obtained in step S1, the development morphology of overburden fractures after mining is simulated using 3DEC numerical simulation, including: upward fracture development height h1, downward fracture development depth h2, and downward fracture tensor d2. The thickness of the unaffected layer is calculated by h = H - h1 - h2, and data with h > 0 are retained. Select the working face height M and aquifer thickness h 水 Thickness H of overlying strata above the coal seam, distance H1 from the overlying aquifer to the coal seam, and permeability coefficient of the overlying strata. Porosity m, upward fracture development height h1, and downward fracture development depth h2 are used as sample data 1; Step S3: Based on the aquifer thickness h obtained in step S1 水 Permeability coefficient of overlying strata With porosity m and fracture development morphology obtained in step S2, a water resource seepage model after full mining damage was established using COMSOL Multiphysics numerical simulation software to obtain the depth q1 of water resources intruding into the rock strata, which was used as sample data 2. Step S4: Construct an intelligent discrimination model for water resource seepage in the barrier layer using the support vector machine algorithm; train the intelligent discrimination model for water resource seepage using sample data 1 as the model input and sample data 2 as the model output. Step S5: After model training is complete, the predicted working face mining height M and aquifer thickness h are set. 水 Thickness H of overlying strata above the coal seam, distance H1 from the overlying aquifer to the coal seam, and permeability coefficient of the overlying strata. Porosity m, upward fracture development height h1, and downward fracture development depth h2 are input into the intelligent water resource seepage discrimination model of the barrier layer to predict the depth q2 of water resources intruding into the rock strata. Combined with the safety factor λ, the effective barrier layer thickness Q is calculated. Step S6: Determine the water-resistant capability based on the effective barrier layer thickness Q; When H1-h1-h2-q2≤0, it is a seepage loss state, and Q=0 is taken; When H1-h1-h2-q2>0, it is an effective water-proof state, and we take... Step S7: Calculate the protective layer thickness P according to the "Specifications for Coal Pillar Retention and Coal Mining in Buildings, Water Bodies, Railways and Main Shafts"; Step S8: Based on the preset error threshold x, compare the effective barrier layer thickness Q and the protective layer thickness P; When Q > P + x, the effective barrier layer is determined to be intact and difficult to damage, and normal mining and periodic monitoring are carried out. When Px≤Q≤P+x, the effective barrier layer is determined to be of the potential damage type. On-site monitoring is carried out while mining is underway, and local treatment is implemented in the lower part of the aquifer when the drainage volume increases. When Q < Px, the effective barrier layer is determined to be vulnerable and easily permeable, and source treatment and local treatment are implemented simultaneously. The source treatment is as follows: when D≤M, backfilling mining is adopted; when D>M, height-restricted mining is adopted. D represents the minimum extendable height of the hydraulic support currently in use in coal mining. The local treatment is as follows: when the infiltration fracture tensor d2 < L, the high-permeability resin grouting method is adopted; when the infiltration fracture tensor d2 > L, the composite aggregate grouting method is adopted. L represents the fracture width specified in the "Code for Construction and Acceptance of Building Materials and Mining Engineering".

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