Method for evaluating water yield property of water-bearing layer of weathered zone of coal measure strata

Abstract

The invention provides a coal measure strata weathering zone aquifer water yield evaluation method, and particularly relates to the technical field of well field exploration. The method specifically comprises the following steps: S1, determining main evaluation indexes for evaluating the water yield property, and constructing an index system for evaluating the water yield property of the aquifer of the stratum weathering zone; s2, data quantification, standardization and normalization processing; s3, determining a subjective weight value and an objective weight value of each main evaluation index through an analytic hierarchy process and an entropy weight method; s4, drawing a water yield property single-factor partition map of each main evaluation index; s5, performing weighted combination on the subjective weight value and the objective weight value of each main evaluation index by using a linear method, and determining a comprehensive weight value of each main evaluation index; s6, constructing an evaluation model of the water yield strength of the aquifer of the to-be-studied area; and S7, based on the stratum weathering zone aquifer water yield property comprehensive partition map, carrying out water yield property evaluation. According to the method, the division grade of the water yield property of the weathering zone aquifer of the coal measure strata in the area range to be researched can be more intuitively evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of minefield exploration, and particularly relates to a method for evaluating the water-richness of an aquifer in the weathered zone of a coal-bearing formation. Background Art

[0002] With the continuous development of the economy, the coal production in China also shows a gradually increasing trend. The problems of water disasters encountered in the coal mining process are endless. In the Jurassic coalfield of Yushenfu Mining Area on the northern Shaanxi slope in the Ordos Basin, the proven coal reserves are as high as 223.6 billion tons, which is one of the mining areas with the richest proven coal reserves in China at present.

[0003] However, after the deposition of the Jurassic strata, this area was affected by the uplifting effect at the end of the Cretaceous, and the strata were severely eroded and weathered. As a result, a bedrock weathered zone was formed at the top of the Jurassic strata. This weathered zone has a certain thickness, the rocks are severely broken, the internal fissures are developed, and the overall structure is loose. Therefore, compared with the intact bedrock below, the rocks in this weathered zone are significantly increased in terms of water storage capacity and permeability, etc., and it is an aquifer with relatively strong water-richness. In addition, the upper coal seams in the Jurassic strata are relatively shallowly buried, and the coal seams are relatively close to the weathered bedrock aquifer. To a great extent, the water-conducting fissure zone formed during the coal seam mining will conduct this bedrock weathered zone aquifer, and even pass through this aquifer. Therefore, this bedrock weathered zone aquifer has become the direct water-inrush aquifer for the shallow coal seam mines in the northern Shaanxi Jurassic coalfield. Therefore, making a reasonable prediction and evaluation of the water-richness distribution of the aquifer in the weathered zone of the coal-bearing formation, studying the water-richness zoning of sandstone rock strata has extremely important theoretical guiding significance and practical value for the safe production of mines.

[0004] At present, to judge the strength of the water-richness of an aquifer, mainly according to the "Regulations on the Prevention and Control of Water Hazards in Coal Mines", according to the value of the unit water inflow (q) of a borehole, the water-richness of the aquifer is divided into the following 4 grades: ① Weak water-richness: q ≤ 0.1 L / (s·m); ② Medium water-richness: 0.1 L / (s·m) < q ≤ 1.0 L / (s·m); ③ Strong water-richness: 1.0 L / (s·m) < q ≤ 5.0 L / (s·m); ④ Extremely strong water-richness: q > 5.0 L / (s·m). However, this method has the following drawbacks in practical engineering applications: Generally, obtaining the q value through the pumping test of a hydrogeological borehole requires a large investment and a long time, so the number of pumping test boreholes for a specific aquifer within the research mining area is extremely limited, and the corresponding unit water inflow measuring points are too few to obtain a comprehensive water-richness zoning result from a small number of points. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for evaluating the water-richness of an aquifer in the weathered zone of a coal-bearing formation. The specific technical solution is as follows: A method for evaluating the water-richness of aquifers in the weathered zone of coal-bearing strata, specifically including the following steps: S1. Determine the main factors affecting the water-richness of aquifers in the weathered zone of strata according to the geological information of the area to be studied. Based on the characteristics of the aquifers in the area to be studied, determine several main influencing factors as the main evaluation indicators for comprehensively evaluating the water-richness, and construct an evaluation index system for the water-richness of aquifers in the weathered zone of strata; S2. Quantify, standardize, and normalize the data of each main evaluation indicator obtained in S1; S3. Determine the subjective weight value and objective weight value of each main evaluation indicator through the analytic hierarchy process and entropy weight method; S4. Use the spatial analysis function of GIS software to draw the isogram of the water-richness of aquifers for each main evaluation indicator, and divide the water-richness of the formation aquifer into different zones according to the subjective weight value and objective weight value of each main evaluation indicator, and obtain the single-factor zoning map of the water-richness of each main evaluation indicator; S5. According to the subjective weight value and objective weight value of each main evaluation indicator in S3, use a linear method to perform weighted combination of the subjective weight and objective weight of each main evaluation indicator to determine the comprehensive weight value of each main evaluation indicator; S6. According to the comprehensive weight value of each main evaluation indicator obtained in S5, construct an evaluation model for the water-richness intensity of the aquifers in the area to be studied, which is used to classify the water-richness level of the area to be studied; S7. Based on the evaluation model for the water-richness intensity of the aquifers in the area to be studied constructed in S6 and combined with the natural break method, use ArcGIS software to classify the water-richness level of the comprehensive zoning map of the water-richness of the aquifers in the weathered zone of strata obtained by overlaying the single-factor zoning maps of the water-richness of each main evaluation indicator under the subjective weight and objective weight, and obtain the water-richness evaluation result.

[0006] Preferably, several main evaluation indicators in S1 include the consumption of flushing fluid, the thickness of weathered bedrock, RQD value, the thickness of the aquifer, the core recovery rate, and the permeability coefficient of the aquifer; among them, the consumption of flushing fluid, the thickness of weathered bedrock, the thickness of the aquifer, and the permeability coefficient of the aquifer are positively correlated with the water-richness intensity of the aquifer; the RQD value and the core recovery rate are negatively correlated with the water-richness intensity of the aquifer.

[0007] Preferably, S2 quantifies the data of the six main evaluation indicators obtained in S1 using Kriging interpolation; Based on the quantified data, perform standardization and normalization processing according to the following two formulas: (1); (2); In formulas (1)-(2): = 1, 2,..., 6; represents the data obtained after standardization and normalization; represents the data values of each main evaluation index before standardization and normalization processing; represents the lower limit of the normalization range, which is taken as 0 here; represents the upper limit of the normalization range, which is taken as 1 here; represents the main evaluation index with the largest quantified value among each main evaluation index; represents the main evaluation index with the smallest quantified value among each main evaluation index; For the main evaluation indexes among the six main evaluation indexes that are positively correlated with the water-richness intensity of the aquifer, direct standardization and normalization processing are carried out using formula (1); for the main evaluation indexes that are negatively correlated with the water-richness intensity of the aquifer, formula (2) is used to convert them into main evaluation indexes that are positively correlated with the water-richness intensity of the aquifer.

[0008] Preferably, in S3, the subjective weight value and objective weight value of each main evaluation index are determined by the analytic hierarchy process and the entropy weight method, which specifically includes the following sub-steps: S3.1 Use the analytic hierarchy process to determine the subjective weight value of each main evaluation index, which specifically includes the following sub-steps: S3.1.1 Establish an analytic hierarchy process model. By analyzing multi-source information such as on-site measured data and indoor and outdoor test data, the six main evaluation indexes obtained in S1 that affect the aquifer in the weathered zone are divided into three levels according to the problems to be studied, their properties, and their influencing factors: The first level: The highest level that considers the six main evaluation indexes as a whole is the target layer, denoted as layer A; The second level: The middle layer that divides the six main evaluation indexes into three categories: aquifer, seepage field, and lithology field is the criterion layer, denoted as layer B; The third level: The lowest level that takes each of the six main evaluation indexes as a single consideration factor is the decision-making layer, denoted as layer C; Among them, in layer B, the aquifer category corresponds to the weathered bedrock thickness and aquifer thickness in layer C; in layer B, the seepage field category corresponds to the flushing fluid consumption and aquifer permeability coefficient in layer C; in layer B, the lithology field category corresponds to the RQD value and core recovery rate in layer C; S3.1.2 Based on the analytic hierarchy process model, construct judgment matrices between layer A and layer B, and between each category of layer B and the two main evaluation indexes in its corresponding layer C; S3.1.3 After standardizing and normalizing the data of each main evaluation index, the importance degree of each main evaluation index affecting the water-richness of the aquifer is subjectively evaluated and scored according to the on-site practice experience in the past on a scale of 1-9 by experts, and the scoring results are filled into the judgment matrix; S3.1.4 Calculate the acceptance consistency test indicators of each judgment matrix , the average value obtained after randomly testing the consistency index , and the maximum eigenvalue corresponding to each judgment matrix ; At the same time, test the consistency of the hierarchical single sorting and the total hierarchical sorting of each judgment matrix: when < 0.1, it means that the consistency of the corresponding judgment matrix meets the required conditions, and the consistency test of the analytic hierarchy process passes; if ≥0.1, it means that the consistency verification of the corresponding judgment matrix fails, and it is necessary to re-examine and adjust the pairwise comparison results in the judgment matrix according to the feedback of experts or by increasing the number of experts and integrating the opinions of more experts until the consistency verification passes; S3.1.5 Based on the judgment matrix with passed consistency verification, obtain the subjective weight values of each main evaluation index in the decision-making layer C layer relative to the target layer A layer through the analytic hierarchy process scoring system; In S3.2, the objective weight values of each main evaluation index are determined by the entropy weight method, which specifically includes the following steps: S3.2.1 Use MATLAB software to establish main evaluation indicators and the matrix M of research objects in each main evaluation index; S3.2.2 Define entropy. Assume that the problem under study has main evaluation indicators and research objects. Define the th research object as: (3); In formula (3), when ; ; ; (4); In formula (4), represents the standardized and normalized value of the th research object under the th main evaluation index; (5); In formula (5): represents the calculation coefficient; S3.2.3 Calculate the entropy weight values of each main evaluation index as the objective weight values of each main evaluation index affecting the water-richness of the aquifer in the area to be studied: (6); In formula (6): ; ; ; represents the information entropy value of the -th main evaluation index of the -th research object.

[0009] Preferably, in S5, a linear method is used to perform a weighted combination of the subjective weights and objective weights of the main evaluation indexes in S3 to determine the comprehensive weight value of each main evaluation index. The calculation formula is: (7); In formula (7): = 1, 2,..., 6; represents the comprehensive weight value of the -th main evaluation index; represents the distribution coefficient of the -th main evaluation index, and the value range of is 0 to 1; represents the subjective weight value of the -th main evaluation index based on the analytic hierarchy process model; represents the objective weight value of the

[0010] -th main evaluation index based on the entropy weight method model. (8); In formula (8): represents the water-richness index; represents the number of main evaluation indexes, = 1, 2,..., 6; represents the value obtained by standardizing and normalizing each main evaluation index, where represents the geographical coordinates; represents the comprehensive weight value of the -th main evaluation index.

[0011] The beneficial effects of the present invention are: Based on the main influencing factors affecting the water-richness of the bedrock weathered zone aquifer, the subjective weight values and objective weight values of each main evaluation index are determined respectively. On the subjective and objective basis, the comprehensive weight value of the two is determined. By superimposing the water-richness single-factor zoning maps of each main evaluation index, the comprehensive zoning map of the water-richness of the weathered zone aquifer in the coal-bearing strata is finally obtained. Based on this map, the water-richness evaluation of the area to be studied is carried out, making up for the deficiencies of the traditional evaluation according to the unit water inflow q value, which has large investment and long time consumption, resulting in extremely limited pumping test boreholes for specific aquifers within the study mining area, and correspondingly too few unit water inflow measuring points, making it impossible to obtain a comprehensive water-richness zoning result evaluation through a small number of points. The evaluation method provided by the present invention is reasonable and practical, and can more intuitively evaluate the classification grade of the water-richness of the weathered zone aquifer in the coal-bearing strata at the area to be studied. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The attached drawings forming part of the description of the present invention are used to provide a further understanding of the present application and do not constitute an improper limitation of the present application.

[0013] Figure 1 is the working flow chart of the inventive method; Figure 2 is the single-factor zoning map of the water-richness of the weathered bedrock thickness; Figure 3 is the single-factor zoning map of the water-richness of the aquifer thickness; Figure 4 is the single-factor zoning map of the water-richness of the RQD value; Figure 5 is the single-factor zoning map of the water-richness of the flushing fluid consumption; Figure 6 is the single-factor zoning map of the water-richness of the core recovery rate; Figure 7 is the single-factor zoning map of the water-richness of the aquifer permeability coefficient; Figure 8 is the analytic hierarchy process model for the water-richness evaluation of the weathered zone aquifer in the strata; Figure 9 is the thematic map of the water-richness of the weathered zone aquifer in the strata under the subjective weight for each main evaluation index; Figure 10 is the thematic map of the water-richness of the weathered zone aquifer in the strata under the objective weight for each main evaluation index; Figure 11 is Figure 9 and Figure 10 the comprehensive zoning map of the water-richness of the weathered zone aquifer in the strata formed by superposition. DETAILED DESCRIPTION OF THE INVENTION

[0014] The specific implementation manner of a method for evaluating the water-richness of the weathered zone aquifer in the coal-bearing strata provided by the present invention is further described in conjunction with the attached drawings and embodiments.

[0015] As shown Figure 1 in the figure, a method for evaluating the water-richness of aquifers in the weathered zone of coal-bearing strata specifically includes the following steps: S1. Determine the main factors affecting the water-richness of aquifers in the weathered zone of strata according to the geological information of the area to be studied. According to the characteristics of the aquifers in the area to be studied, determine several main influencing factors as the main evaluation indicators for comprehensively evaluating the water-richness, and construct an evaluation index system for the water-richness of aquifers in the weathered zone of strata: The several main evaluation indicators in S1 include the consumption of flushing fluid, the thickness of weathered bedrock, RQD value, the thickness of aquifers, the core recovery rate, and the permeability coefficient of aquifers. Among them, the consumption of flushing fluid, the thickness of weathered bedrock, the thickness of aquifers, and the permeability coefficient of aquifers are positively correlated with the water-richness intensity of aquifers; the RQD value and the core recovery rate are negatively correlated with the water-richness intensity of aquifers.

[0016] S2. Quantify the data of the six main evaluation indicators obtained in S1 using Kriging interpolation, and perform standardization and normalization processing based on the quantified data according to the following two formulas: (1); (2); In formulas (1)-(2): i = 1, 2,..., 6; represents the data obtained after standardization and normalization; represents the data value of each main evaluation indicator before standardization and normalization processing; represents the lower limit of the normalization range, which is taken as 0 here; represents the upper limit of the normalization range, which is taken as 1 here; represents the main evaluation indicator with the largest quantified value among the main evaluation indicators; represents the main evaluation indicator with the smallest quantified value among the main evaluation indicators; For the main evaluation indicators that are positively correlated with the water-richness intensity of aquifers among the six main evaluation indicators, formula (1) is directly used for standardization and normalization processing; for the main evaluation indicators that are negatively correlated with the water-richness intensity of aquifers, formula (2) is used to convert them into main evaluation indicators that are positively correlated with the water-richness intensity of aquifers for subsequent application.

[0017] S3. Determine the subjective weight value and objective weight value of each main evaluation indicator through the analytic hierarchy process and entropy weight method, specifically including the following sub-steps: S3.1 Use the analytic hierarchy process to determine the subjective weight value of each main evaluation indicator, specifically including the following sub-steps: S3.1.1 Establish an analytic hierarchy process model. By analyzing multi-source information of on-site measured data and indoor and outdoor test data, divide the six main evaluation indexes obtained in S1 that affect the aquifer in the weathered zone of the stratum into three levels according to the problems, natures and influencing factors to be studied: The first level: The highest level that considers the six main evaluation indexes as a whole is the target layer, denoted as layer A; The second level: The middle level that divides the six main evaluation indexes into three categories: aquifer, seepage field and lithology field is the criterion layer, denoted as layer B; The third level: The lowest level that takes each of the six main evaluation indexes as a single consideration factor is the decision-making layer, denoted as layer C; Among them, the aquifer category in layer B corresponds to the weathered bedrock thickness and aquifer thickness in layer C; the seepage field category in layer B corresponds to the flushing fluid consumption and aquifer permeability coefficient in layer C; the lithology field category in layer B corresponds to the RQD value and core recovery rate in layer C; S3.1.2 Based on the analytic hierarchy process model, construct judgment matrices between layer A and layer B, and between each category of layer B and the two main evaluation indexes in its corresponding layer C; S3.1.3 After standardizing and normalizing the data of each main evaluation index, subjectively evaluate and score the importance of each main evaluation index affecting the water-richness of the aquifer according to the scale of 1-9 based on past on-site practice experience through the method of expert scoring, and fill the scoring results into the judgment matrix; S3.1.4 Calculate the consistency test indexes of each judgment matrix , the average value obtained after randomly testing the consistency index and the maximum eigenvalue corresponding to each judgment matrix ; At the same time, test the consistency of the single-layer ranking and the total-layer ranking of each judgment matrix: when < 0.1, it means that the consistency of the corresponding judgment matrix meets the required conditions, and the consistency test of the analytic hierarchy process passes; if ≥0.1, it means that the consistency verification of the corresponding judgment matrix fails, and it is necessary to re-examine and adjust the pairwise comparison results in the judgment matrix according to the feedback of experts or by increasing the number of experts and integrating the opinions of more experts until the consistency verification passes; S3.1.5 Based on the judgment matrix with passed consistency verification, obtain the subjective weight values of each main evaluation index in the decision-making layer C relative to the target layer A through the analytic hierarchy process scoring system; In S3.2, the entropy weight method is used to determine the objective weight values of each main evaluation index, which specifically includes the following steps: S3.2.1 Use MATLAB software to establish The main evaluation indicators and in each main evaluation indicator The matrix M of the research objects; S3.2.2 Define entropy. Assume that the problem under study has The main evaluation indicators and The research objects. Define the th research object as: (3); In formula (3), when ; ; ; (4); In formula (4), Represents the standardized and normalized value of the th research object under the th main evaluation indicator; (5); In formula (5): Represents the calculation coefficient; S3.2.3 Calculate the entropy weight value of each main evaluation indicator as the objective weight value of each main evaluation indicator affecting the water-richness of the aquifer in the area to be studied: (6); In formula (6): ; ; ; Represents the information entropy value of the th research object under the th main evaluation indicator.

[0018] S4. Use the spatial analysis function of GIS software to draw the contour map of the water-richness of the aquifer for each main evaluation indicator, and divide the water-richness of the formation aquifer into different zones according to the subjective weight value and objective weight value of each main evaluation indicator to obtain the single-factor zoning map of the water-richness of each main evaluation indicator; S5. According to the subjective weight value and objective weight value of each main evaluation indicator in S3, use the linear method to perform weighted combination on the subjective weight and objective weight of each main evaluation indicator to determine the comprehensive weight value of each main evaluation indicator. The calculation formula is: (7); In formula (7): = 1, 2,..., 6; Represents the comprehensive weight value of the th main evaluation indicator; Represents the The distribution coefficient of each main evaluation index, ranges from 0 to 1; represents the subjective weight value of the th main evaluation index based on the analytic hierarchy process model; represents the th main evaluation index based on the objective weight value of the entropy weight method model.

[0019] S6. Based on the comprehensive weight values of each main evaluation index obtained in S5, construct an evaluation model for the aquifer water-richness intensity in the area to be studied, which is used to classify the water-richness level of the area to be studied. The specific calculation formula is: (8); In formula (8): represents the water-richness index; represents the number of main evaluation indexes, = 1, 2,..., 6; represents the values obtained by standardizing and normalizing each main evaluation index. Among them, represents the geographical coordinates; represents the th comprehensive weight value of the main evaluation index.

[0020] S7. Based on the evaluation model for the aquifer water-richness intensity in the area to be studied constructed in S6 and combined with the natural break method, use ArcGIS software to classify the water-richness level of the comprehensive zoning map of the aquifer water-richness in the weathered bedrock zone obtained by overlaying the single-factor zoning maps of the water-richness of each main evaluation index under the subjective weight and the objective weight, and obtain the water-richness evaluation result.

[0021] The following further illustrates the present invention with examples: In a certain mining area, the 2-2 coal seam in the main mining well field of the mining area is mainly mined. The direct water-inrush aquifer is the weathered bedrock aquifer, which is continuously distributed on the top of the bedrock in the well field, with a developed thickness of 14.34 - 67.65 m and an average of 39.84 m. The elevation of the bedrock surface ranges from 1124.53 m to 1229.75 m, with an average of 1185.07 m. Generally, it is higher in the southeast and lower towards the northwest. The lithology is mainly variegated siltstone, mudstone, and sandstone, with a relatively loose structure and well-developed fractures. The water-richness of the weathered bedrock is restricted by topography, the characteristics of the overlying aquifer, weathering degree, and bedrock lithology.

[0022] According to the borehole pumping test data, the water level depth is 2.58 m - 12.27 m, the elevation is 1218.41 m - 1231.91 m, the specific capacity is q = 0.00401 (L / s.m) - 0.04332 (L / s.m), and the permeability coefficient is K = 0.0253 m / d - 0.04807 m / d. It is an aquifer with weak water-richness. The specific evaluation process is as follows: S1. Determine the main factors affecting the water-richness of aquifers in the weathered zone of strata based on the geological information of the area to be studied. According to the characteristics of the aquifers in the area to be studied, determine six main influencing factors (flushing fluid consumption, thickness of weathered bedrock, RQD value, thickness of aquifer, core recovery rate, permeability coefficient of aquifer) as the main evaluation indicators for comprehensively evaluating the water-richness, and construct an evaluation index system for the water-richness of aquifers in the weathered zone of strata: In this embodiment, the data adopted for the six main evaluation indicators are shown in Table 1-6 below:

[0023] Table 1. Thickness of weathered bedrock

[0024] Table 2. Thickness of aquifer

[0025] Table 3. RQD value

[0026] Table 4. Flushing fluid consumption

[0027] Table 5. Core recovery rate

[0028] Table 6. Permeability coefficient of aquifer

[0029] It should be noted here that under natural conditions, after a long period of weathering and erosion, the porosity of the rock will increase compared to the original, and the corresponding water storage capacity will also be stronger than the original. Therefore, the water-richness of the rock after erosion and weathering will be relatively stronger, and the greater the thickness of the weathered bedrock, the stronger its water-richness. That is to say, the thickness of the weathered bedrock is positively correlated with the water-richness intensity of its aquifer, that is, the greater the thickness of the weathered bedrock, the stronger its water-richness; generally, the water-richness intensity of the aquifer is positively correlated with the thickness of the aquifer, that is, if the thickness of the aquifer is greater, then its water-richness is stronger; the RQD value is an index that can more intuitively reflect the integrity of the rock and soil mass. Generally, if the integrity of the rock and soil mass is stronger, then its water permeability is relatively weaker. Therefore, the RQD value is negatively correlated with the water-richness intensity of the aquifer in the weathered bedrock zone, that is, the lower the RQD value, the stronger the water-richness intensity of the aquifer; the consumption of the drilling fluid can reflect the development degree of the rock formation, karst or fissures, and at the same time reflects the lithology and water permeability of the rock formation. The consumption of the drilling fluid is positively correlated with the water-richness intensity of the aquifer, that is, the greater the consumption of the drilling fluid, the stronger the water-richness of its aquifer; the core recovery rate is an influencing factor that can intuitively reflect the development degree of the fissures in the rock formation, and generally, the core recovery rate is negatively correlated with the water-richness intensity of the aquifer in the weathered zone of the formation, that is, if the core recovery rate is higher, then the water-richness intensity of the aquifer is weaker; the permeability coefficient of the aquifer can accurately reflect the migration ability of the rock formation to water bodies and substances, and can also reflect the flow situation of the underground water body and the migration situation of the solutes in the water body. Generally, the permeability coefficient of the aquifer is positively correlated with the water-richness intensity of the aquifer, that is, the relatively greater the permeability coefficient of the aquifer, the relatively stronger its water-richness intensity.

[0030] S2. Quantify the data of the six main evaluation indicators in Table 1-6 using Kriging interpolation, and perform standardization and normalization processing on the quantified data according to the following formulas (1)-(2): (1); (2); In formulas (1)-(2): = 1, 2,..., 6; represents the data obtained after standardization and normalization; represents the data value of each main evaluation indicator before normalization processing; represents the lower limit of the normalization range, which is taken as 0 here; represents the upper limit of the normalization range, which is taken as 1 here; represents the main evaluation indicator with the largest quantified value among the main evaluation indicators; represents the main evaluation indicator with the smallest quantified value among the main evaluation indicators; It should be noted here that the consumption of flushing fluid, the thickness of the aquifer, the thickness of the weathered bedrock, and the permeability coefficient of the aquifer are directly standardized and normalized using formula (1) for future use; the RQD value and the core recovery rate are converted into the main evaluation indicators that are positively correlated with the water-richness intensity of the aquifer using formula (2) for future use.

[0031] Preferably, in S3, the subjective weight value and the objective weight value of each main evaluation indicator are determined by the analytic hierarchy process and the entropy weight method: S3.1 Use the analytic hierarchy process to determine the subjective weight value of each main evaluation indicator, which specifically includes the following sub-steps: S3.1.1 Establish an analytic hierarchy model. By analyzing multi-source information such as on-site measured data and indoor and outdoor test data, the six main evaluation indicators obtained in S1 that affect the aquifer in the weathered zone are divided into three levels according to the problems, natures, and influencing factors to be studied, as Figure 8 shown: The first level: The highest level that considers the six main evaluation indicators as a whole consideration factor is the target level, denoted as level A; The second level: The middle level that divides the six main evaluation indicators into three categories: aquifer, seepage field, and lithology field is the criterion level, denoted as level B; The third level: The lowest level that considers each of the six main evaluation indicators as a single consideration factor is the decision-making level, denoted as level C.

[0032] Among them, the aquifer category in level B corresponds to the thickness of the weathered bedrock and the thickness of the aquifer in level C; the seepage field category in level B corresponds to the consumption of flushing fluid and the permeability coefficient of the aquifer in level C; the lithology field category in level B corresponds to the RQD value and the core recovery rate in level C; S3.1.2 Based on the analytic hierarchy model, construct judgment matrices between level A and level B, and between each category of level B and the two main evaluation indicators in its corresponding level C; S3.1.3 After standardizing and normalizing the data of each main evaluation indicator, the importance degree of each main evaluation indicator affecting the water-richness of the aquifer is subjectively evaluated and scored on a scale of 1 to 9 according to past on-site practice experience through expert scoring, and the scoring results are filled into the judgment matrix:

[0033] Judgment matrix A~B q (q=1~3)

[0034] Obtain =3.000, =0.000, =0.580, =0.000 0.1, Judgment matrix A~B q Consistency test passed;

[0035] Judgment matrix B 1 ~C e (e = 1~2)

[0036] Obtained = 2.000, = 0.000, = 0.580, = 0.000 0.1, Judgment matrix B 1 ~C e Consistency test passed;

[0037] Judgment matrix B 2 ~C f (f = 3~4)

[0038] Obtained = 3.012, = 0.006, = 0.580, = 0.010 0.1, Judgment matrix B 2 ~C f Consistency test passed;

[0039] Judgment matrix B 3 ~C g (g = 5~6)

[0040] Obtained = 2.000, = 0.000, = 0.000, = 0.000 0.1, Judgment matrix B 3 ~C g Consistency test passed; S3.1.5 Based on the judgment matrix with passed consistency verification, the subjective weight values of each main evaluation index in the decision-making layer C relative to the target layer A are obtained through the hierarchical analysis scoring system, as shown in Table 7 below:

[0041] Table 7. Subjective weight values of each main evaluation index based on the analytic hierarchy process

[0042] In S3.2, the entropy weight method is used to determine the objective weight values of the main evaluation indicators, which specifically includes the following sub-steps: S3.2.1 Based on the data of the main evaluation indicators obtained in S2, after quantization, standardization, and normalization processing, use MATLAB software to establish a matrix M formed by 6 main evaluation indicators and 13 research objects in each main evaluation indicator, as shown in Table 8 below:

[0043] Table 8. Matrix M

[0044] S3.2.2 Define entropy according to formulas (3)-(5): (3); In formula (3), when ; = 1, 2, 3…, 13; = 1, 2,…, 6; (4); (5); S3.2.3 Use the formula Calculate the entropy weight values of the main evaluation indicators as the objective weight values of the main evaluation indicators affecting the water-richness of the aquifer in the study area, as shown in Table 9 below:

[0045] Table 9. Objective weight values of the main evaluation indicators based on the entropy weight method

[0046] S4. Use the spatial analysis function of GIS software to draw the isograms of the water-richness of the aquifer for each main evaluation indicator, and according to the subjective weight values and objective weight values of each main evaluation indicator, divide the water-richness of the formation aquifer into different zones to obtain the single-factor zoning maps of the water-richness of each main evaluation indicator, as Figures 2 - 7 shown; among them, Figure 9 is the thematic map of the water-richness of the formation weathered zone aquifer for each main evaluation indicator generated only considering the subjective weight; Figure 10 is the thematic map of the water-richness of the formation weathered zone aquifer for each main evaluation indicator generated only considering the objective weight.

[0047] S5. According to the subjective weight values and objective weight values of the main evaluation indicators obtained from Table 7 and Table 9, use the formula (in this embodiment take 0.6) to obtain the comprehensive weight values of the main evaluation indicators, as shown in Table 10 below:

[0048] Table 10. Comprehensive weight values of the main evaluation indicators

[0049] In S6, an evaluation model for the water-richness intensity of the aquifer in the area to be studied is constructed according to the comprehensive weight values in Table 10, and is used for classifying the water-richness grades in the area to be studied: ; S7. Combining the evaluation model for the water-richness intensity of the aquifer in the area to be studied constructed in S6 with the natural break method, using ArcGIS software to overlay the single-factor zoning maps of the water-richness of each main evaluation index under the subjective weight and the objective weight to obtain the comprehensive zoning map of the water-richness of the aquifer in the weathered zone of the strata (as Figure 11 shown), and classifying the water-richness grades. The water-richness of the aquifer in the weathered zone of the strata in this mining area is classified into five grade regions: weak, relatively weak, medium, relatively strong, and strong (it should be noted here that, for the accuracy of the evaluation results, the two relatively graded regions of the relatively weak water-richness region and the relatively strong water-richness region need to be excluded during the evaluation and do not participate in the grading standard in the specification). According to the water-richness grade region to which the area to be studied belongs in the position of this comprehensive zoning map, the evaluation result of the water-richness of the aquifer in the weathered zone of the strata in this area can be intuitively completed.

[0050] In the present invention, terms such as "upper", "lower", "bottom", "top", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention, and do not specifically refer to the present invention or the element, and should not be construed as a limitation to the present invention. Terms such as "connected" and "joined" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and should not be construed as a limitation to the present invention.

[0051] Of course, the above description is not a limitation to the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the substantial scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for evaluating the water-richness of aquifers in a weathered zone of coal-bearing strata, characterized in that: The specific steps include: S1. Determine the main factors affecting the water-richness of the aquifer in the stratum weathering zone based on the geological information of the area to be studied, determine several main influencing factors as the main evaluation indicators for comprehensive evaluation of water-richness based on the characteristics of the aquifer in the area to be studied, and construct an evaluation indicator system for the water-richness of the aquifer in the stratum weathering zone; S2. Quantify, standardize and normalize the data of each major evaluation index obtained in S1; S3. Determine the subjective weight and objective weight of each main evaluation index through the hierarchical analysis method and entropy weight method; S4. Use the spatial analysis function of GIS software to draw contour maps of water-bearing layer water-bearing properties of each main evaluation index, and divide the water-bearing layer water-bearing properties into different zones according to the subjective weight value and objective weight value of each main evaluation index, and obtain the single factor zone map of water-bearing properties of each main evaluation index; S5. According to the subjective weight value and objective weight value of each main evaluation indicator in S3, the subjective weight and objective weight of each main evaluation indicator are weighted and combined by using a linear method to determine the comprehensive weight value of each main evaluation indicator; S6. Based on the comprehensive weight values ​​of the main evaluation indicators obtained in S5, a water-bearing intensity evaluation model of the aquifer in the area to be studied is constructed to grade the water-bearing intensity of the area to be studied; S7. Based on the S6 component, the water-rich intensity evaluation model of the aquifer in the study area is combined with the natural break method. The ArcGIS software is used to superimpose the single factor zoning maps of the main evaluation indicators under subjective weights and objective weights to obtain a comprehensive zoning map of water-rich aquifers in the weathering zone, and the water-richness grade is divided to obtain the water-richness evaluation result.

2. The method for evaluating water richness of aquifers in weathered zones of coal-bearing strata according to claim 1, characterized in that: Some of the main evaluation indicators mentioned in S1 include flushing fluid consumption, weathered bedrock thickness, RQD value, aquifer thickness, core sampling rate, and aquifer permeability coefficient; Among them, the flushing fluid consumption, weathered bedrock thickness, aquifer thickness, and aquifer permeability coefficient are positively correlated with the water-richness intensity of the aquifer; the RQD value and core sampling rate are negatively correlated with the water-richness intensity of the aquifer.

3. The method for evaluating water richness of aquifers in weathered zones of coal-bearing strata according to claim 2, characterized in that: S2 quantifies the six main evaluation index data obtained in S1 using Kriging interpolation; The quantified data is standardized and normalized according to the following two formulas: （1）； （2）； In formula (1)-(2): =1,2,…,6; Represents the data obtained after standardization and normalization; Represents the data values ​​of each main evaluation index before standardization and normalization; Indicates the lower limit of the normalized range, which is 0 here; Indicates the upper limit of the normalized range, which is 1 here; It represents the main evaluation index with the largest quantitative value among all the main evaluation indexes; Indicates the main evaluation index with the smallest quantitative value among all the main evaluation indexes; Among the six main evaluation indicators, the main evaluation indicators that are positively correlated with the water-richness intensity of the aquifer are directly standardized and normalized using formula (1); the main evaluation indicators that are negatively correlated with the water-richness intensity of the aquifer are converted into main evaluation indicators that are positively correlated with the water-richness intensity of the aquifer using formula (2).

4. The method for evaluating water richness of aquifers in weathered zones of coal-bearing strata according to claim 3, characterized in that: S3 determines the subjective weight value and objective weight value of each main evaluation index by using the hierarchical analysis method and the entropy weight method, which specifically includes the following sub-steps: S3.1 Use the analytic hierarchy process to determine the subjective weight values ​​of each major evaluation indicator, which includes the following steps: S3.1.1 Establish a hierarchical analysis model. By analyzing the multi-source information of field measured data and indoor and outdoor test data, the six main evaluation indicators affecting the aquifer in the weathering zone of the stratum obtained in S1 are divided into three levels according to the problems to be studied, their properties and their influencing factors: The first level: the highest level with six main evaluation indicators as overall considerations is the target level and is recorded as level A; The second level: the middle layer of the six main evaluation indicators divided into three categories of aquifer, seepage field and lithology field is taken as the criterion layer and recorded as B layer; The third level: the lowest level with the six main evaluation indicators as single considerations is the decision-making level and is recorded as the C level; Among them, the aquifer type in the B layer corresponds to the weathered bedrock thickness and aquifer thickness in the C layer; the seepage field type in the B layer corresponds to the flushing fluid consumption and aquifer permeability coefficient in the C layer; the lithology field type in the B layer corresponds to the RQD value and core sampling rate in the C layer; S3.1.2 Based on the analytic hierarchy model, construct a judgment matrix between the two main evaluation indicators in the A layer and the B layer, and between each type of B layer and its corresponding C layer; S3.1.3 After the data of each major evaluation index is standardized and normalized, the importance of each major evaluation index affecting the water-bearing property of the aquifer is subjectively evaluated and scored on a scale of 1 to 9 based on previous field practice experience, and the scoring results are filled in the judgment matrix; S3.1.4 Calculate the acceptance consistency test index of each judgment matrix , the average value obtained after random inspection of consistency index And the maximum eigenvalue corresponding to each judgment matrix ; At the same time, the consistency of the hierarchical single ranking and the hierarchical total ranking of each judgment matrix is ​​tested: 0.1, it means that the consistency of the corresponding judgment matrix meets the required conditions, and the consistency test of the hierarchical analysis method passes; if ≥0.1, it means that the corresponding judgment matrix consistency verification fails, and it is necessary to re-examine and adjust the pairwise comparison results in the judgment matrix based on the feedback of experts or by increasing the number of experts and integrating the opinions of more experts until the consistency verification passes; S3.1.5 Based on the judgment matrix that has passed the consistency verification, the subjective weight values ​​of each main evaluation index in the decision-making layer C relative to the target layer A are obtained through the hierarchical analysis scoring system; The entropy weight method is used to determine the objective weight values ​​of each main evaluation index in S3.2, which specifically includes the following steps: S3.2.1 Using MATLAB software to establish The main evaluation indicators and the main evaluation indicators The matrix M of the research objects; S3.2.2 Define entropy, assuming that the problem under study has The main evaluation indicators and research subjects, The research object is defined as: （3）； In formula (3), when ; ; ; （4）； In formula (4), Indicates Under the main evaluation indicators, Standardized and normalized values ​​for each study object; （5）； In formula (5): represents the calculation coefficient; S3.2.3 Calculate the entropy weight of each major evaluation index as the objective weight value of each major evaluation index affecting the water-richness of the aquifer in the study area: （6）； In formula (6): ; ; ; Indicates The first The information entropy value of the main evaluation index.

5. The method for evaluating water richness of aquifers in weathered zones of coal-bearing strata according to claim 4, characterized in that: In S5, the subjective weight and objective weight of each main evaluation index in S3 are weighted and combined by using the linear method to determine the comprehensive weight value of each main evaluation index. The calculation formula is: （7）； In formula (7): =1,2,…,6; Indicates The comprehensive weight value of the main evaluation indicators; Indicates The distribution coefficient of the main evaluation indicators, The value range of is 0 to 1; Indicates The main evaluation indicators are based on the subjective weight values ​​under the hierarchical analysis model; Indicates The main evaluation indicators are based on the objective weight values ​​under the entropy weight method model.

6. The method for evaluating water richness of aquifers in weathered zones of coal-bearing strata according to claim 5, characterized in that: In S6, according to the comprehensive weight values ​​of the main evaluation indicators obtained in S5, an evaluation model for the water-bearing intensity of the aquifer in the area to be studied is constructed to classify the water-bearing grade of the study area. The specific calculation formula is: （8）； In formula (8): It represents the water richness index; Indicates the number of main evaluation indicators, =1,2,…,6; It means that the main evaluation indicators are standardized and normalized to obtain the numerical value, where Represents geographic coordinates; Indicates The comprehensive weight value of the main evaluation indicators.

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