Method for arranging ground pumping and draining holes of coal mine aquifer within working face range

Abstract

The invention discloses a coal mine aquifer ground pumping and drainage hole arrangement method within a working face range, which comprises the following steps of: judging a main control layer position fracture position during a working face mining period based on an identified water inrush separation zone layer position; determining a pumping and drainage hole layout scheme based on the fracture position of the main control layer; judging the disturbance degree of the water inrush separation zone, quantifying the disturbance degree of the water inrush separation zone based on a disturbance degree judgment result to obtain a water inrush separation zone disturbance degree judgment quantification result, and judging the working face as a strong disturbance type working face or a weak disturbance type working face according to the judgment quantification result; and for the determined strong disturbance type working face, the pumping and drainage drilling construction opportunity is determined according to the following principle that when the working face is pushed to pass through the safe construction distance of the pumping and drainage drilling design position, pumping and drainage drilling construction is conducted. According to the method, the situation that the pump drainage holes are deformed and damaged is avoided or reduced, the pump drainage efficiency is improved, the pump drainage effect is more stable, and engineering safety is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of mine water hazard prevention and control, and in particular relates to a method for arranging ground drainage holes in a coal mine aquifer within a working face. Background Art

[0002] Mine water hazards are one of the most common and difficult disasters in the coal mine production process, posing a serious threat to mine safety and miners' lives. When water-conducting fissures develop to the roof aquifer, water will flow down to the working face, causing roof water inrush; and when the rock strata around the aquifer undergo uneven settlement to form a delamination, delamination water may form at the bottom or inside the aquifer, causing highly destructive delamination water hazards. Therefore, the control of roof water hazards is of great practical significance for mine safety production and miners' life safety.

[0003] Effective control of water sources is one of the key methods to control roof water hazards. Take the Yonglong mining area in Shaanxi Province in the Ordos Basin as an example. The mining area has typical Jurassic-Cretaceous overburden conditions. During the mining of the working face in some mines, high-level stratum water will form at the junction of the Jurassic and Cretaceous systems, resulting in the threat of stratum water inrush at the working face. At present, the control of roof water hazards mainly depends on underground drainage. The specific method for the control of roof stratum water is to drill holes to the stratum where the stratum water accumulates, destroy the water accumulation in the stratum space, and then drain the stratum water to achieve the purpose of preventing and controlling water hazards. However, when the aquifer or stratum water accumulation layer is too high from the coal seam, the underground backhole construction is difficult and the drainage effect is often unsatisfactory. For example, Cuimu Coal Mine in Huanglong Mining Area uses ground direct diversion holes to drain stratum water. This method prevents the formation of stratum water accumulation to a certain extent. However, due to the complex geological conditions of the Jurassic-Cretaceous strata, the temporal and spatial development of the abscission layer is difficult to accurately predict, and the ground-through diversion holes constructed in some mines (such as Zhaoxian Coal Mine and Guojiahe Coal Mine, etc.) cannot accurately and effectively drain the abscission layer water. In response to the above problems, related studies have proposed a method of constructing ground drainage holes, which can reduce the water pressure of the aquifer and the abscission layer by draining the aquifer and the abscission layer, slow down the water filling speed of the abscission layer, and thus inhibit the formation of large-scale abscission layer water, achieving good prevention and control effects.

[0004] However, the current layout of the drainage holes within the working face lacks scientific basis and mainly relies on empirical judgment. The drainage holes are prone to deformation and damage, resulting in unstable actual drainage effects and difficulty in adapting to complex geological conditions and the impact of mining disturbances. Therefore, a comprehensive determination method is urgently needed to scientifically and reasonably arrange the ground drainage holes to improve the drainage efficiency and ensure the safety of the project. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a method for arranging ground drainage holes in a coal mine aquifer within the working face, so as to solve the problem that the ground drainage holes in coal mines in the prior art rely on experience in their arrangement, the drainage holes are prone to deformation and damage, resulting in unstable actual drainage effects, and difficulty in adapting to complex geological conditions and the influence of mining disturbances.

[0006] The object of the present invention is achieved in that:

[0007] A method for arranging ground drainage holes of a coal mine aquifer within a working face range comprises the following steps:

[0008] Based on the identified water inrush detachment zone, the fracture position of the main controlling layer during the mining of the working face is determined;

[0009] Determine the layout of the drainage holes based on the fracture position of the main control layer;

[0010] The disturbance degree of the water inrush detachment zone is judged, and the disturbance degree of the water inrush detachment zone is quantified based on the result of the disturbance degree judgment, so as to obtain the quantified result of the disturbance degree judgment of the water inrush detachment zone, and the working face is judged as a strong disturbance type working face or a weak disturbance type working face according to the result;

[0011] For the determined strongly disturbed working face, the timing of the extraction and drainage drilling construction is determined according to the following principles: when the working face is pushed beyond the safe construction distance of the designed position of the extraction and drainage drilling, the extraction and drainage drilling construction is carried out.

[0012] Further, the method for determining the fracture position of the main controlling layer during the mining of the working face includes one or more of the following methods:

[0013] Method 1: Determine the fault position of the main controlling layer based on the key layer theory;

[0014] Method 2: Determine the square fracture position based on the square theory and take the square fracture position as the fracture position of the main controlling layer;

[0015] Method three: Based on the elastic thick plate theory, the breaking position of the water bursting detachment zone is determined, and the breaking position of the water bursting detachment zone is taken as the breaking position of the main controlling layer.

[0016] Furthermore, the drainage hole layout plan is determined based on the fracture position of the main control layer:

[0017] In the direction of the working face advancement, the first drainage borehole shall be constructed before the first square area, and the first drainage borehole shall be located after the water level begins to drop abnormally, and the remaining drainage boreholes shall be located between adjacent squares;

[0018] The location of the drainage drilling holes should avoid the water bursting stratum zone and the key stratum fracture position;

[0019] Adjust the drilling position according to the surface undulations and specific construction conditions on site.

[0020] Furthermore, a comprehensive discrimination coefficient Q of the stratum dislocation tendency is calculated, and based on the comprehensive discrimination coefficient Q of the stratum dislocation tendency, a quantitative discrimination result of the disturbance degree of the water inrush detachment zone is obtained.

[0021] Furthermore, based on the interlayer physical property difference coefficient, interlayer shear strength and interlayer maximum shear stress, the comprehensive discrimination coefficient Q of the formation dislocation tendency is obtained;

[0022] The calculation formula of the comprehensive discrimination coefficient Q of stratum dislocation tendency is:

[0023] Q = α(1-R) ​​+ βW;

[0024] In the above formula, α, β are weight coefficients; W is the interlaminar physical property difference coefficient; R is the interlaminar shear strength [τ] and the maximum shear stress τ max The ratio of

[0025] Among them, the calculation formula of the interlayer physical property difference coefficient W is:

[0026]

[0027] Among them, E 1 , E 2 is the elastic modulus of the adjacent upper and lower strata, GPa; ν 1 , ν 2 is the Poisson's ratio of the adjacent upper and lower strata; ρ 1 , ρ 2 is the density of the adjacent upper and lower rock layers, kg / m 3 .

[0028] Furthermore, the calculation formula of interlaminar shear strength [τ] is:

[0029]

[0030] Among them, Λ i is the elastic modulus of rock layer i, GPa; h i is the thickness of the i-th rock layer, m; γ i is the density of the i-th rock layer, KN / m 3 ; i = 1, 2, 3...n; φ is the internal friction angle, °; C is the cohesion of the rock formation, MPa.

[0031] Furthermore, based on the calculated value of the comprehensive discrimination coefficient Q, the disturbance degree of the water inrush detachment zone is comprehensively judged:

[0032] When the comprehensive discriminant coefficient Q of the stratum dislocation tendency is ≥ 0.3, the quantified result of the disturbance degree of the water inrush detachment zone is a strong disturbance type, and the working face at this time is a strong disturbance type working face;

[0033] When the comprehensive discrimination coefficient Q of the stratum dislocation tendency is less than 0.3, the quantitative discrimination result of the disturbance degree of the water inrush detachment zone is weak disturbance type, and the working face at this time is a weak disturbance type working face.

[0034] Furthermore, for the determined weakly disturbed working face, there is no need to consider the timing of the extraction and drainage drilling construction, and the extraction and drainage drilling construction can be carried out normally.

[0035] Furthermore, the safe construction distance is calculated according to the following formula:

[0036]

[0037] In the above formula, L min is the safe construction distance, m; α 1 is the empirical coefficient reflecting the subsidence evolution rate; D is the coal seam burial depth, m; H is the coal seam mining height, m; H 0 As the reference mining height, 1m is taken; η is the ratio for determining the stability of subsidence.

[0038] Furthermore, the method for arranging ground drainage holes in a coal mine aquifer within the working face range also includes: identifying the water inrush detachment zone based on geological and hydrological data of the mining area and the working face.

[0039] Compared with the prior art, the method for arranging ground drainage holes in a coal mine aquifer within the working face range provided by the present invention comprehensively considers the fracture law of overburden rock, proposes a judgment formula for the fracture position of the water bursting detachment zone, and scientifically and reasonably proposes a scheme for arranging drainage holes within the working face range, which can avoid or reduce the deformation and damage of the drainage holes, improve the drainage efficiency, make the drainage effect more stable, and ensure the safety of the project.

[0040] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0042] Figure 1 A schematic cross-sectional diagram of the overburden strata division for mining in the Jurassic coalfield provided by the present invention;

[0043] Figure 2 A schematic diagram of the fracture position of the main controlled layer of the working face provided by the present invention;

[0044] Figure 3 A schematic diagram of the location and construction timing of the drainage holes for the strongly disturbed working face provided by the present invention;

[0045] Figure 4 A schematic diagram of the operation flow of the method for arranging ground drainage holes in a coal mine aquifer within the working face provided by the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] To facilitate the understanding of the embodiments of the present application, the following will be further explained with reference to the accompanying drawings, and the embodiments do not constitute a limitation on the embodiments of the present application. In the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence may be performed in a different order than described. For example, two continuously described processes may be performed substantially simultaneously or in an order opposite to the described order. In addition, the same reference numerals represent the same components.

[0048] The terms used here are for the purpose of describing specific embodiments, and are not intended to be restrictive. As used here, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, it is explained that there are stated features, integral bodies, steps, operations, parts, assemblies and / or their groups, but it is not excluded that there are or add one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups. It should also be noted that, as used here, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values ​​and / or the values ​​provided that will be recognized by those of ordinary skill in the art.

[0049] Example 1

[0050] A specific embodiment of the present invention, as Figures 1 to 4 As shown, a method for arranging ground drainage holes of a coal mine aquifer within a working face is disclosed, including steps S1 to S5, which are specifically as follows:

[0051] S1. Based on the geological and hydrological data of the mining area and working face, identify the water inrush detachment zone.

[0052] This step S1 is the basis of the whole method, which aims to clarify the engineering geological and hydrogeological conditions of the mining area and provide the necessary geological background for the subsequent steps. In this step S1, the engineering geological and hydrogeological conditions are first surveyed, and the geological and hydrological data of the mining area and the working face are collected to identify the potential water inrush abscission zone. The identified water inrush abscission zone is one of the main control layers for all subsequent analyses, and provides basic data for the subsequent main control layer fracture position determination and disturbance degree determination.

[0053] S11. Engineering geology and hydrogeological conditions survey

[0054] (1) Data collection: Collect geological data of the mining area and working face, including exploration drilling data, hydrogeological data, stratigraphic columnar diagrams, stratigraphic profiles, etc. Obtain coal seam mining information, including mining depth, mining thickness, mining methods, and mining disturbance characteristics. Collect the distribution, thickness, water pressure, and development of water-conducting fractures of the aquifer.

[0055] (2) Geological model construction: Based on the collected geological data, the stratigraphic system, thickness, lithology, structure and burial depth of each rock layer are clarified. The engineering geological rock groups are divided, and the coal seams, main aquifers and impermeable layers are identified. An engineering geological model of the mining overburden is established to clarify the coal seam mining information and the spatial location of the water inrush abscission zone (distance from the coal seam), such as Figure 1 shown.

[0056] S12. Identify the water bursting detachment zone based on the engineering geological conditions method.

[0057] Definition of water inrush abscission zone: The water inrush abscission zone refers to the composite layer that can cause abscission water inrush, which must meet the following two basic conditions:

[0058] Condition 1: There is a combined structure of upper hard rock layer and lower impermeable layer. During the mining process, the upper hard rock layer and the lower impermeable layer form a separation space due to uneven settlement, and the lower impermeable layer does not develop conductive cracks during the bending deformation process, and still maintains a certain degree of impermeability.

[0059] Condition 2: The closed abscission space is located near the aquifer. Usually the upper hard rock layer is the aquifer. During the development of the abscission layer, groundwater continues to gather in the closed abscission space, forming abscission water body, which becomes the direct source of abscission water inrush.

[0060] The composition of the water bursting abscission zone includes, from bottom to top:

[0061] (1) Subordinate aquiclude: low permeability rock formations such as mudstone, mudstone, siltstone, shale, etc.

[0062] (2) Waterlogged abscission layer: a closed abscission space formed between the upper hard rock layer and the lower impermeable layer.

[0063] (3) Upper hard rock layer: usually an aquifer, with rock types including fine sandstone, medium sandstone, coarse sandstone, conglomerate, etc.

[0064] In one optional embodiment, the following steps are used to identify the water inrush separation zone:

[0065] Step S121: According to the comprehensive stratigraphic columnar diagram and cross-sectional diagram of the mining area and working face, the lithology, thickness and spatial distribution of each rock layer are clarified.

[0066] Step S122: Divide the engineering geological rock groups and identify the coal seams, main aquifers and impermeable layers.

[0067] Step S123: Analyze the deformation characteristics of the overburden rock caused by mining and determine the rock strata combination that may form delamination.

[0068] Step S124: combining the hydrogeological conditions, identifying the composite layer that meets the two basic conditions of the water inrush detachment zone.

[0069] Step S125: marking the spatial position of the water inrush stratum zone in the mining overburden engineering geological model to clarify its distance from the coal seam.

[0070] S2. Based on the identified water bursting detachment zone, the fracture position of the main controlling layer during the working face mining is determined.

[0071] On the basis of the water bursting detachment zone identified by S1, S2 further analyzes the fracture positions of these water bursting detachment zone layers during the mining process. The "main control layer" in this embodiment is not a single type of layer, but includes three layers: key layer, square fracture position, and water bursting detachment zone. Through a series of mechanical models and fracture discrimination methods established in steps S21, S22, and S23, the positions of the key layer, square position, and water bursting detachment zone are calculated respectively. Step S24 comprehensively determines the fracture position of the main control layer based on all the fracture position results obtained in steps S21, S22, and S23. These fracture positions directly affect the safety and effectiveness of the arrangement of the drainage holes on the working face, and serve as the key reference basis for the location of the drainage drilling holes.

[0072] S21. Determine the fracture position of the main control layer based on the key layer theory. According to the key layer theory, identify the position of the sub-key layer and the main key layer, and calculate the initial fracture distance L of the key layer. f and periodic breaking distance L c , based on the initial breaking distance L of the key layer f and periodic breaking distance L c Determine the breaking position of the key layer.

[0073] The key layer theory is one of the important methods to determine the fracture position of overburden rock caused by mining. The key layer here is the main controlling layer, which is divided into sub-key layer and main key layer. Its fracture position has an important influence on the stability of overburden rock and water hazard prevention. First, the key layer position of overburden rock is identified according to the key layer theory, and then the initial fracture distance L of the key layer is determined according to the elastic beam theory. f and periodic breaking distance L c It can be calculated by the following formula:

[0074]

[0075] σ t is the tensile strength of the key layer, MPa; h is the thickness of the key layer, m; q is the load on the key layer, MPa, including self-weight stress and overlying rock load.

[0076] Therefore, the critical layer breaking positions of the working face are respectively f L f +nL c at (where n=1, 2, 3...).

[0077] S22. Determine the square fracture position based on the square theory, and use the square fracture position as the fracture position of the main controlling layer; specifically, use the position that is an integer multiple of the oblique length of the cutting eye working face as the fracture position of the main controlling layer.

[0078] The square theory holds that when the working face advances to an integer multiple of the oblique length of the working face, the overburden is prone to square fracture. Therefore, the position at an integer multiple of the oblique length of the cutting eye working face is regarded as the fracture position of the square theory. The specific judgment method is as follows: Let the oblique length of the working face be L w , then the distance between the square breaking position and the cutting eye is n×L w , where n is an integer (n=1, 2, 3, ...). The square fracture position is determined by analyzing the deformation characteristics of the overburden during the advancement of the working face.

[0079] S23. Based on the elastic thick plate theory, the breaking position of the water bursting detachment zone is determined, and the breaking position of the water bursting detachment zone is taken as the breaking position of the main controlling layer.

[0080] The breaking position of the water bursting detachment zone directly affects the formation and evolution of detachment water accumulation. Based on the elastic thick plate theory, the breaking criterion of the upper rock layer and the lower aquiclude in the water bursting detachment zone is obtained as follows:

[0081]

[0082] in, For the initial break and periodic break, the following conditions must be met:

[0083] For the first break, B 1 , B 2 Satisfy the following formula:

[0084]

[0085] A in the above formula 1 The calculation formula is:

[0086] For cycle breaking, B 1 , B 2 Satisfy the following formula:

[0087]

[0088] The calculation formula of A' in the above formula is:

[0089] In the above formulas: are the rock cohesion and internal friction angle respectively; μ and E are the equivalent Poisson's ratio and elastic modulus of the rock layer respectively; a, b, h are the dip width, strike span and thickness of the rock layer exposed in the "water bursting abscission zone" respectively; P is the load on the rock layer. For the lower impermeable layer, P = (1-λ)[P w (Δt)+γh], where P w is the water pressure of the stratum water, x and y are the coordinate values ​​of the rock formation. Since the maximum bending moment is located at the center of the plate, x=a / 2 and y=b / 2 are taken.

[0090] Substituting all known parameters except the strike span b into formula (3), the specific value of the strike span b corresponding to the initial breaking of the water inrush detachment zone can be calculated. This value is the initial breaking distance of the water inrush detachment zone, denoted as X 1 At the same time, the specific value of the strike span b corresponding to the periodic breaking of the water inrush detachment zone is calculated. This value is the periodic breaking distance of the water inrush detachment zone, recorded as X 2 Finally, the breaking position of the water inrush detachment zone can be determined as: 1 X 2 +mLc (where m=1,2,3......).

[0091] S24. Based on the fracture position determination results determined in steps S21-S23, a comprehensive determination is made on the fracture position of the main control layer within the working face to determine the comprehensive fracture position of the main control layer within the working face, and a fracture position map is drawn.

[0092] The comprehensive fracture position of the main control layer after comprehensive judgment is marked on the working face plan to form a clear main control layer fracture position map, such as Figure 2 This figure will show the distribution of fractures in each layer within the working face, provide a visual basis for determining the location of subsequent drainage hole drilling, and assist in assessing the mining risk of the mining area. This step aims to determine all fracture locations of the main control layer within the working face based on the previous analysis results, and draw a fracture location map to support the determination of subsequent drilling locations.

[0093] S3. Determine the layout plan of the drainage holes based on the main control layer fracture position determined in step S2.

[0094] This step is based on the comprehensive fracture position of the main control layer determined in step S2, and a specific layout plan for the drainage holes in the working face is formulated. To ensure construction safety and drainage effect, the following layout principles are followed:

[0095] (1) Principles for selecting the area for the first drilling construction:

[0096] In the direction of the working face advancement, the first drainage borehole is constructed before the first square area, and the first drainage borehole should be arranged after the water level begins to drop abnormally, so as to improve the drainage efficiency of the abscission layer water. The specific location of the abnormal water level drop is determined based on the experience of the mined working face. The remaining drainage boreholes are located between adjacent squares.

[0097] (2) Principles for determining the location of the extraction drilling holes:

[0098] The location of the drainage drilling holes should avoid the water bursting detachment zone and the fracture position of the key layer, and the relatively stable formation conditions should be used to ensure the construction quality of the drainage holes.

[0099] (3) Principle of flexible adjustment:

[0100] The final drilling position should also be appropriately adjusted according to the surface undulations and specific construction conditions on site to ensure construction feasibility and project safety.

[0101] S4. The disturbance degree of the water inrush detachment zone is judged, and the disturbance degree of the water inrush detachment zone is quantified based on the disturbance degree judgment result, so as to obtain the quantified result of the disturbance degree judgment of the water inrush detachment zone, and the working face is judged as a strong disturbance type working face or a weak disturbance type working face accordingly.

[0102] This step focuses on analyzing the disturbance degree of the water inrush abscission zone. Specifically, by defining the comprehensive discrimination coefficient of the stratum dislocation tendency, it evaluates whether the abscission zone is strongly disturbed during the mining process and quantifies the degree of disturbance, thus providing necessary information for optimizing the timing of subsequent drilling construction.

[0103] S41. Based on the interlayer physical property difference coefficient, interlayer shear stress and interlayer shear strength, the stratum dislocation tendency is determined, and a comprehensive determination coefficient Q of the stratum dislocation tendency is obtained, and based on the comprehensive determination coefficient Q, a determination result of the stratum dislocation tendency is obtained.

[0104] Under high-intensity mining conditions, the interlayer dislocation tendency of the overburden is a key factor affecting the stability of the drainage hole. In order to quantitatively identify the dislocation tendency of adjacent rock strata, based on the results of rock group division, combined with interlayer physical property differences, shear stress and shear strength, a dislocation index based on interlayer physical property differences, interlayer shear stress calculation and shear strength identification method are proposed.

[0105] S411. Calculate the inter-layer physical property difference coefficient W.

[0106] The difference in physical properties between layers is an important factor leading to the tendency of dislocation. Define the coefficient of physical property difference between layers W:

[0107]

[0108] Among them, E 1 , E 2 is the elastic modulus of the adjacent upper and lower strata, GPa; ν 1 , ν 2 is the Poisson's ratio of the adjacent upper and lower strata; ρ 1 , ρ 2 is the density of the adjacent upper and lower rock layers, kg / m 3 .

[0109] S412. Calculate the maximum interlayer shear stress and shear strength;

[0110] The "water bursting abscission zone" is an engineering geological rock group composed of multiple rock layers, so the rock layers in the water bursting abscission zone are numbered 1, 2, 3, ..., i, ..., n from bottom to top. Based on the multi-layer rock beam theory, the maximum shear stress between layers of an engineering geological rock group composed of multiple rock layers under deadweight is τ max :

[0111]

[0112] In the formula, h i is the thickness of the i-th rock layer, m; X is the distance from the neutral plane to the bottom surface, m; Ψ i is the moment of inertia of rock layer i, m 4; l is the span of the fixed beam, that is, the length of the working surface, m; γ i is the density of the i-th rock layer, KN / m 3 , i = 1, 2, 3...n; MAX refers to the maximum value of all interlaminar shear stresses.

[0113] Interlaminar shear stress is the direct driving force that causes dislocation. Assuming that the maximum value of all interlaminar shear stresses is located in rock layer i, the calculation formula for interlaminar shear strength [τ] is:

[0114] [τ] = σ ni tanφ+C (6)

[0115] Among them, σ ni is the normal stress on the upper surface of rock layer i, MPa, which is calculated by superposition of the self-weight stress of the overburden rock and the disturbance stress caused by mining; φ is the internal friction angle; C is the cohesion of the rock layer, MPa.

[0116] Normal stress σ on the upper surface of rock layer i ni for:

[0117]

[0118] Λ i is the elastic modulus of rock layer i, GPa.

[0119] Substituting formula (7) into formula (6), the calculation formula for interlaminar shear strength [τ] is obtained as follows:

[0120]

[0121] S413. Calculate the ratio R of interlaminar shear strength to maximum shear stress:

[0122] R=[τ] / τ max (8)

[0123] S414, based on the interlayer physical property difference coefficient W obtained in step S411 and the interlayer maximum shear stress τ calculated in step S412 max The interlayer shear strength [τ] and the ratio R of the interlayer shear strength to the maximum shear stress calculated in step S413 are used to obtain the comprehensive discrimination coefficient Q of the stratum dislocation tendency.

[0124] The calculation formula of the comprehensive discrimination coefficient Q of stratum dislocation tendency is:

[0125] Q=α(1-R)+βW (9)

[0126] Where: α, β are weight coefficients, which are determined according to actual engineering conditions, usually α = 0.4, β = 0.3; W is the interlaminar physical property difference coefficient; R is the ratio of interlaminar shear strength to maximum shear stress.

[0127] S42. Based on the comprehensive discrimination coefficient Q of the formation dislocation tendency calculated in step S41, a quantitative discrimination result of the disturbance degree of the water bursting detachment zone is obtained, and the working face is discriminated as a strong disturbance type working face or a weak disturbance type working face accordingly.

[0128] Specifically, based on the value of the comprehensive discrimination coefficient Q obtained in step S41, a quantitative discrimination result of the disturbance degree of the water inrush detachment zone is obtained, and the disturbance degree of the water inrush detachment zone is comprehensively judged according to the following rules:

[0129] (1) When the comprehensive discriminant coefficient Q of the stratum dislocation tendency is ≥ 0.3, the quantitative result of the discrimination of the disturbance degree of the water inrush detachment zone is a strong disturbance type, and the working face at this time is a strong disturbance type working face.

[0130] (2) When the comprehensive discriminant coefficient Q of the stratum dislocation tendency is less than 0.3, the quantitative result of the discrimination of the disturbance degree of the water inrush detachment zone is weak disturbance type, and the working face at this time is a weak disturbance type working face.

[0131] S5. For the strongly disturbed working face determined in step S4, the timing of the drainage drilling construction is determined according to the following principles: when the working face exceeds the safe construction distance L of the designed location of the drainage drilling min For the weak disturbance type working face determined in step S4, there is no need to consider the timing of the extraction and drainage drilling construction, and the extraction and drainage drilling construction can be carried out normally.

[0132] During the coal mining process, the overburden will be deformed, damaged and sink due to the influence of mining. For the strongly disturbed working face determined in step S4, the severe disturbance will cause the borehole to deform or even be damaged, affecting the drainage effect. If the drilling is carried out before the working face reaches the target position or has not yet passed the target position, the overburden is still in the deformation and damage stage, and the borehole may be damaged due to sinking and deformation, affecting its normal function. In order to ensure construction safety, a method for optimizing the timing of construction is proposed, that is, after the working face has passed the target position by a certain distance, the drilling construction is carried out after the overburden sinks and stabilizes. Therefore, the key to the timing of drilling construction for strongly disturbed working faces lies in the reasonable calculation of the minimum safe distance required for the working face to pass the designed position of the borehole.

[0133] The subsidence of the overburden is not only related to the burial depth, but also closely related to the mining height of the coal seam. The mining height determines the intensity of the goaf effect, which in turn affects the final subsidence amount and subsidence rate of the overburden. This step is based on the burial depth and mining height of the working face. The minimum safe construction advancement distance required for safe construction drilling after the working face is advanced to the target position is deduced as L min That is to say, in order to ensure that the overburden sinking is basically stable, the working face must at least be pushed past the safe construction distance L of the designed borehole. min .

[0134] Assuming that the working face advances by a distance of L, the subsidence of the overburden follows an exponential evolution law, and the subsidence model is:

[0135]

[0136] Among them, δ∞ is the final stable subsidence of the overburden, m; λ is the characteristic attenuation distance of the overburden subsidence process, which is affected by the burial depth and mining height; L is the advancement distance of the working face (i.e., the advancement distance behind the target position), m.

[0137] In order to reflect the regulation of the sinking rate by the burial depth and mining height, the characteristic attenuation distance λ of the overburden sinking process is calculated according to the following formula:

[0138]

[0139] Where D is the depth of coal seam, m; H is the mining height of coal seam, m; H 0 For reference mining height, standardized parameters, usually 1m; α 1 is the empirical coefficient reflecting the subsidence evolution rate;

[0140] It is required that the drilling construction be carried out when the overburden sinks to the final stable value η (e.g. 95%) at the target location, i.e.

[0141] δ(L)≥ηδ ∞ (12)

[0142] Here, η is the ratio for determining whether the sinking is stable (for example, 0.95 means that 95% of the final sinking amount is reached).

[0143] Substituting formula (12) into the sinking model (10) yields the following formula:

[0144]

[0145] After further arrangement, the advancement distance satisfies the following formula:

[0146] L≥-λln(1-η) (14)

[0147] Substituting equation (11) into equation (14), we can get the minimum distance that the working surface needs to pass through the designed position of the drainage drilling hole: L min , L min The calculation formula is:

[0148]

[0149] That is to say, Figure 3 As shown in the figure, when the working surface is pushed past the designed position of the extraction drilling hole, the distance is L minWhen the overburden is subsided, the extraction drilling construction is started, which can ensure that the overburden sinking is basically stable and safe mining can be achieved.

[0150] Compared with the prior art, the method for arranging ground drainage holes in a coal mine aquifer within the working face provided in this embodiment comprehensively considers the fracture law of overburden rock, proposes a judgment formula for the fracture position of the water bursting detachment zone, and scientifically and reasonably proposes a scheme for arranging drainage holes within the working face. It can avoid or reduce the deformation and damage of the drainage holes, improve the drainage efficiency, make the drainage effect more stable, and ensure the safety of the project.

[0151] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for arranging ground drainage holes in a coal mine aquifer within a working face, characterized in that: The steps include: Based on the identified water inrush detachment zone, the fracture position of the main controlling layer during the mining of the working face is determined; Determine the layout of the drainage holes based on the fracture position of the main control layer; The disturbance degree of the water inrush detachment zone is judged, and the disturbance degree of the water inrush detachment zone is quantified based on the result of the disturbance degree judgment, so as to obtain the quantified result of the disturbance degree judgment of the water inrush detachment zone, and the working face is judged as a strong disturbance type working face or a weak disturbance type working face according to the result; For the determined strongly disturbed working face, the timing of the extraction and drainage drilling construction is determined according to the following principles: when the working face is pushed beyond the safe construction distance of the designed position of the extraction and drainage drilling, the extraction and drainage drilling construction is carried out.

2. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: Methods for determining the fracture position of the main controlling layer during working face mining include one or more of the following methods: Method 1: Determine the fault position of the main controlling layer based on the key layer theory; Method 2: Determine the square fracture position based on the square theory and take the square fracture position as the fracture position of the main controlling layer; Method three: Based on the elastic thick plate theory, the breaking position of the water bursting detachment zone is determined, and the breaking position of the water bursting detachment zone is taken as the breaking position of the main controlling layer.

3. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: The layout plan of the drainage holes is determined based on the fracture position of the main control layer: In the direction of the working face advancement, the first drainage borehole shall be constructed before the first square area, and the first drainage borehole shall be located after the water level begins to drop abnormally, and the remaining drainage boreholes shall be located between adjacent squares; The location of the drainage drilling holes should avoid the water bursting stratum zone and the key stratum fracture position; Adjust the drilling position according to the surface undulations and specific construction conditions on site.

4. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: The comprehensive discrimination coefficient Q of the stratum dislocation tendency is calculated, and based on the comprehensive discrimination coefficient Q of the stratum dislocation tendency, a quantitative discrimination result of the disturbance degree of the water inrush detachment zone is obtained.

5. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 4, characterized in that: Based on the interlayer physical property difference coefficient, interlayer shear strength and interlayer maximum shear stress, the comprehensive discrimination coefficient Q of the stratum dislocation tendency is obtained; The calculation formula of the comprehensive discrimination coefficient Q of stratum dislocation tendency is: Q = α(1-R) ​​+ βW; In the above formula, α, β are weight coefficients; W is the interlaminar physical property difference coefficient; R is the interlaminar shear strength [τ] and the maximum shear stress τ max The ratio of Among them, the calculation formula of the interlayer physical property difference coefficient W is: Where E1, E2 are the elastic moduli of the adjacent upper and lower rock layers, GPa; ν1, ν2 are the Poisson's ratios of the adjacent upper and lower rock layers; ρ1, ρ2 are the densities of the adjacent upper and lower rock layers, kg / m 3 .

6. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 5, characterized in that: The calculation formula of interlaminar shear strength [τ] is: Among them, Λ i is the elastic modulus of rock layer i, GPa; h i is the thickness of the i-th rock layer, m; γ i is the density of the i-th rock layer, KN / m 3 ; i = 1, 2, 3...n; φ is the internal friction angle, °; C is the cohesion of the rock formation, MPa.

7. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 5, characterized in that: Based on the calculated value of the comprehensive discrimination coefficient Q, the disturbance degree of the water inrush detachment zone is comprehensively judged: When the comprehensive discriminant coefficient Q of the stratum dislocation tendency is ≥ 0.3, the quantified result of the disturbance degree of the water inrush detachment zone is a strong disturbance type, and the working face at this time is a strong disturbance type working face; When the comprehensive discrimination coefficient Q of the stratum dislocation tendency is less than 0.3, the quantitative discrimination result of the disturbance degree of the water inrush detachment zone is weak disturbance type, and the working face at this time is a weak disturbance type working face.

8. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: For the determined weakly disturbed working face, there is no need to consider the timing of the extraction and drainage drilling construction, and the extraction and drainage drilling construction can be carried out normally.

9. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: The safe construction distance is calculated according to the following formula: In the above formula, L min is the safe construction distance, m; α1 is the empirical coefficient reflecting the subsidence evolution rate; D is the coal seam burial depth, m; H is the coal seam mining height, m; H0 is the reference mining height, which is 1m; η is the ratio for determining subsidence stability.

10. The method for arranging ground drainage holes of a coal mine aquifer within the working face range according to claim 1, characterized in that: Also includes: Based on the geological and hydrological data of the mining area and the working face, the water inrush detachment zone is identified.

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