Ordovician limestone water disaster early warning method based on middle indication layer method and application

Abstract

The invention discloses a middle indicator layer method Ordovician limestone water disaster early warning method and application, and relates to the technical field of coal seam mining. The method solves the problems that the formation and disaster-causing mechanism of the current collapse column is not completely clear, and the floor water damage caused by the collapse column cannot be accurately predicted and prevented, gets rid of the high dependence on the formation and disaster-causing mechanism, and has the advantages of high accuracy, strong practicability and relatively small investment. The method is applied in three aspects of early warning of the tunneling roadway, water disaster risk evaluation of the stope face and water disaster risk evaluation of the regional floor, and accurate early warning of the Ordovician limestone water disaster of the tunneling roadway, safe mining of the working face of the complex region and safety evaluation of the three-level partial region are achieved. And the method is suitable for North China coal field mines and has popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of coal seam mining, and in particular to a method and application for early warning of Ordovician limestone water disaster by means of an intermediate indicator layer method. Background Art

[0002] In North China type coalfields, since the coal measures strata are directly distributed above the Ordovician limestone strata, the Ordovician limestone aquifer underlying the coal seams has strong water-richness, sufficient recharge, and high water head pressure. The highest Ordovician limestone water pressure in the mine can reach 8 MPa. Although the distance between the lowest workable coal seam and the Ordovician limestone aquifer is large, and the water inrush coefficient of the Ordovician limestone aquifer in the mine field is less than 0.06 MPa / m, which meets the requirements of mining with pressure-bearing safety. However, due to the existence of concentrated water-conducting channels of karst collapse columns, the Ordovician limestone water can be conducted through the collapse columns to approach or penetrate the workable coal seams, posing a great threat to the safe production of the mine.

[0003] The relevant theoretical research and exploration methods for floor water disasters and collapse columns have been enriched and improved, but Ordovician limestone water disaster accidents caused by the conduction of collapse columns still occur from time to time. In the past decade or so, all the Ordovician limestone water inrush accidents that have occurred in North China type coalfields are caused by the deep high-pressure Ordovician limestone water being conducted and lifted by collapse columns under the condition that the evaluation of the floor thickness meets the requirements of mining with pressure-bearing safety. In the areas where the floor thickness is evaluated to be able to meet the requirements of mining with pressure-bearing safety, the Ordovician limestone water will still enter the mining coal seams through the concentrated water-conducting channels of collapse columns and cause water inrush accidents. There is still no conclusion on the relevant research on the formation mechanism and cause of collapse columns. The surface geophysical exploration and point-like drilling exploration methods are costly and prone to omission, and water inrush seems to be impossible to completely avoid.

[0004] There have been many relevant studies on floor water disasters and collapse columns. Generally speaking, the prevention and control of Ordovician limestone water disasters in North China type coalfields have the following problems:

[0005] (1) Under the condition that the floor thickness meets the requirements of mining with pressure-bearing safety, cases of water inrush caused by the conduction of deep Ordovician limestone water by collapse columns occur from time to time in China.

[0006] (2) The mechanism research and evaluation methods of floor water disasters are still difficult to fully cover various types of floor pressure-bearing mining situations and problems.

[0007] (3) The understanding of the formation mechanism of collapse columns is not clear, the exploration difficulty is large, and a sound and systematic prevention and control technology system has not been formed. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention provides a method for preventing and controlling floor water disasters caused by coal mine collapse columns, namely the "intermediate indicator layer method", which returns the floor water disaster problem of the conduction of collapse columns to Ordovician limestone water (abbreviation of Ordovician karst water) itself, makes up for the deficiencies in the research on floor pressure-bearing mining and collapse columns, and has achieved good practical results.

[0009] In the first aspect, the present invention provides a method for early warning of Ordovician limestone water disaster by means of an intermediate indicator layer, and the steps are as follows:

[0010] S1. Collect geological and hydrogeological exploration data of the mine field to obtain the regional geological and hydrogeological conditions, and determine the intermediate indicator layer according to the stratigraphic structure and lithological combination characteristics from the coal seam to be mined to the Ordovician limestone top interface;

[0011] S2. Analyze the stratigraphic structure and hydrogeological characteristics of the Ordovician limestone aquifer and the intermediate indicator layer, and analyze the differences in water level, water quality, water temperature and hydrogeological characteristics and the spatio-temporal distribution law of the differences;

[0012] S3. Clarify the relevance between the intermediate indicator layer and the early warning of Ordovician limestone water disaster from three perspectives: water level early warning, water quality early warning and water temperature early warning;

[0013] S4. Determine the discriminant indicators for the early warning of Ordovician limestone water disaster in the intermediate indicator layer, including water level early warning indicators, water quality early warning indicators and water temperature early warning indicators, and establish a scoring standard for each early warning discriminant indicator;

[0014] S5. Establish a discriminant system for the early warning of Ordovician limestone water disaster in the intermediate indicator layer by using the comprehensive scoring method and the fuzzy comprehensive evaluation method respectively;

[0015] S6. Evaluate the high-risk areas of Ordovician limestone water disaster in the mine field by using the discriminant system of the comprehensive scoring method early warning and the discriminant system of the fuzzy comprehensive evaluation early warning respectively.

[0016] Preferably, when S3 determines the relevance between the intermediate indicator layer and the Ordovician limestone water disaster, a conceptual model for the upward conduction of deep Ordovician limestone water by the mine collapse column is established, and the feflow numerical simulation software is used to simulate the influence range of the water level, water temperature and water quality characteristics when the water-conducting collapse column conducts the Ordovician limestone water to the intermediate indicator layer under the conditions of the stratigraphic lithology and structure of this coal mine, the hydrogeological parameters of the Ordovician limestone aquifer and the intermediate indicator layer.

[0017] Preferably, compared with the water quality of the Ordovician limestone aquifer and the intermediate indicator layer, the contents of sodium ions, magnesium ions, chloride ions and sulfate ions in the Ordovician limestone water are relatively low, and nitrate ions commonly exist in the Ordovician limestone water, while nitrate ions hardly exist in the water of the intermediate indicator layer.

[0018] Preferably, the water temperature of the Ordovician limestone aquifer is higher than that of the intermediate indicator layer, and the early warning of Ordovician limestone water disaster is achieved by judging the abnormal temperature of the mining water inflow or the borehole water inflow.

[0019] Preferably, the water level early warning indicators in S4 include the water level difference between adjacent areas of the same layer of the intermediate indicator layer, the water level difference between two intermediate indicator layers and the degree of water level drawdown of the intermediate indicator layer;

[0020] The water quality warning indicators in S4 include the content of nitrate ions and other hydrochemical characteristics. Other hydrochemical characteristics include the contents of sodium ions, magnesium ions, chloride ions, sulfate ions and total hardness;

[0021] The water temperature warning indicator in S4 is the water temperature difference of the same layer in the intermediate indicator layer.

[0022] Preferably, the comprehensive scoring method warning discrimination system in S5 is to score each warning indicator in the area to be evaluated according to the single warning score of the warning indicator, and determine the warning levels of the Ordovician limestone water disaster in the area to be evaluated as five levels: first, second, third, fourth and no warning according to different comprehensive warning score values.

[0023] In the second aspect, the present invention also provides an application of the above-mentioned Ordovician limestone water disaster warning method of the intermediate indicator layer method, including the application of the Ordovician limestone water disaster warning method of the intermediate indicator layer method in the risk warning of Ordovician limestone water disaster in the driving roadway, the risk assessment of the Ordovician limestone water disaster in the floor of the mining face and the risk assessment of the Ordovician limestone water disaster in the advanced exploration results of the regional floor.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention solves the problem that the formation and disaster-causing mechanism of current collapse columns are not yet fully clear, and it is impossible to accurately predict and prevent the floor water disaster caused by collapse columns, getting rid of the high dependence on its formation and disaster-causing mechanism, and having the advantages of high accuracy, strong practicability and relatively small investment. And this method has been applied in three aspects: warning in the driving roadway, risk assessment of water disaster in the mining face, and risk assessment of regional floor water disaster, realizing accurate warning of Ordovician limestone water disaster in the driving roadway, safe mining of the working face in the complex area and safety assessment of some areas in the third level. It is applicable to the mines in the North China type coalfield and has the value of popularization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the stratigraphic columnar section of the intermediate indicator layer of Fan Gezhuang Mine;

[0026] Figure 2 It is a schematic diagram of the conceptual model of the flow field of the intermediate indicator layer I;

[0027] Figure 3 It is a schematic diagram of the subtype of the conceptual model of the flow field of the intermediate indicator layer I;

[0028] Figure 4 It is a schematic diagram of the conceptual model of the flow field of the intermediate indicator layer II;

[0029] Figure 5 It is the contour map of the numerical simulation water level of the aquifer at the 12th coal floor of Model I;

[0030] Figure 6 It is the contour map of the numerical simulation water level of the aquifer from the 14th coal floor to K3 of Model I;

[0031] Figure 7This is the contour map of water level in the numerical simulation of the 12 coal floor aquifer in Model 2;

[0032] Figure 8 This is the contour map of water level in the numerical simulation of the 14 coal floor ~ K3 aquifer in Model 2;

[0033] Figure 9 This is a comparison chart of the main hydrochemical characteristics of the intermediate indicator layer and the Ordovician aquifer;

[0034] Figure 10 This is the water temperature distribution map of the middle indicator layer;

[0035] Figure 11 It is the water temperature characteristic relationship diagram;

[0036] Figure 12 This is an assessment map of the high-risk areas for water disasters in the Ordovician mining area. DETAILED DESCRIPTION

[0037] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific implementation methods, but the present invention is not limited thereto.

[0038] The present invention provides an intermediate indicator layer method for early warning of limestone water damage, the steps of which are as follows:

[0039] S1. Collect geological and hydrogeological exploration data of the well field, obtain regional geological and hydrogeological conditions, and determine the intermediate indicator layer based on the stratigraphic structure and lithological combination characteristics from the mineable coal seam to the top interface of the Ordovician ash.

[0040] S2. Analyze the stratigraphic structure and hydrogeological characteristics of the Ordovician grayiquid and the intermediate indicator layer, and analyze the differences in water level, water quality, water temperature and hydrogeological characteristics and the temporal and spatial distribution patterns of the differences, and analyze the flow field characteristics of the well field.

[0041] S3. Clarify the correlation between the intermediate indicator layer and the Aoshui flood warning from three perspectives: water level warning, water quality warning and water temperature warning.

[0042] S4. Determine the early warning and discrimination indicators of the middle indicator layer Ordovician flood disaster, including water level early warning indicators, water quality early warning indicators and water temperature early warning indicators.

[0043] S5. Use comprehensive scoring method and fuzzy comprehensive evaluation method to establish the early warning and discrimination system of Ordovician flood disaster in the intermediate indicator layer.

[0044] S6. Use the comprehensive scoring method early warning judgment system and the fuzzy comprehensive evaluation early warning judgment system to evaluate the high-risk areas of the Ordovician limestone flood in the well field. The water level, water quality and water temperature data actually obtained from the project are brought into the judgment system to output the Ordovician limestone flood warning level. According to different warning levels, corresponding governance methods are adopted.

[0045] Definition of the intermediate indicator layer: For the North China type Carboniferous-Permian coalfield, if the thin aquifer system with weak water-richness and weak water-conductivity within the section from the bottom coal seam that can be mined in the coal series to the underlying Ordovician aquifuge layer is relatively independent, and the water environment state parameters such as water level, water temperature, and water chemical composition characteristics are significantly different from those of the underlying Ordovician karst aquifer system, then this aquifer system is called the intermediate indicator layer for early warning of the underlying floor karst water disaster.

[0046] The method of early warning and prevention of the underlying floor Ordovician karst water disaster based on the abnormal water environment parameters of the intermediate indicator layer is called the intermediate indicator layer method.

[0047] Taking the mining area where the applicant is located as an example for illustration, where 12 coal and 14 coal are the names of coal seams, not the labels in the attached drawings:

[0048] S1. Determine the intermediate indicator layer.

[0049] The mine strata are of the typical characteristics of the North China type coalfield. The distance between the bottom coal seam 12 that can be mined and the Ordovician limestone aquifer is relatively large. The floor evaluation by the water inrush coefficient method meets the requirements of safe mining with pressure. However, in history, there have been water inrush and shaft flooding accidents caused by the connection of Ordovician water through collapse columns. There are two relatively independent confined aquifers with good sealing between the coal seams that can be mined and the Ordovician limestone aquifer. These two confined aquifers are suitable as the intermediate indicator layer for preventing the occurrence of Ordovician water disasters in the mine.

[0050] Specifically, the intermediate indicator layer of the Fangezhuang Mine consists of two weakly water-rich aquifer groups. One is the sandstone fissure weakly water-rich aquifer group between the floor of coal seam 12 in the lower Permian Zhaogezhuang Formation and the roof of coal seam 14 in the upper Carboniferous Kaiping Formation (abbreviated as coal floor aquifer 12); the other is the aquifer group composed of the sandstone fissure aquifer at the floor of coal seam 14 in the upper Carboniferous Kaiping Formation to (and including) the top K3 thin limestone of the underlying Tangshan Formation (abbreviated as 14 coal floor - K3 aquifer) as Figure 1 shown.

[0051] S2. Analyze the stratigraphic structure and hydrogeological characteristics of the intermediate indicator layer, and combine the locally mastered hydrogeological anomaly data in history to summarize the differential characteristics of the intermediate indicator layer and the Ordovician limestone aquifer in terms of water level, water quality, and water temperature.

[0052] Between the bottom coal seam 12 that can be mined in the Fangezhuang Mine and the Ordovician limestone, a stable 12 coal floor aquifer and 14 coal floor - K3 aquifer have been formed. A stable aquifuge layer has been formed between the K3 limestone and the top interface of the Ordovician limestone, which well separates the high-pressure Ordovician water in the lower part from the 14 coal floor - K3 aquifer and the coal series strata above it. Such stratigraphic structure characteristics and combination relationships are the key for the 12 coal floor aquifer and 14 coal floor - K3 aquifer to be used as the intermediate indicator layer.

[0053] The middle indicator layer is generally weakly water-rich. The unit water inflow shows a trend of being larger in the northern wing of the minefield and decreasing towards the southern and deeper regions. The middle indicator layer mainly receives recharge from the alluvial layer in the outcrop area. The water level gradually decreases from the eastern outcrop area to the western deep region. Locally, due to water-conducting collapse columns, it receives vertical recharge from the Ordovician limestone. Mine drainage is the main discharge method. The water quality of the middle indicator layer is generally calcium magnesium bicarbonate type water without nitrate ions, while the Ordovician limestone water contains nitrate ions up to 11 mg / l. The water temperature of the middle indicator layer generally shows the characteristic of being lower in the north and higher in the south. The lowest measured water temperature in the northern wing area is 17.7 °C, about 2 °C lower than the water temperature of the Ordovician limestone water in the same area.

[0054] In 1989, the water release test in the northern wing area divided this area into three hydrogeological units: the 2298 high water level area, the north second strip area, and the 208 high water level area. The high water level anomaly characteristics of the exploration boreholes in the aquifers at the bottom of the No. 12 coal seam and the aquifers from the bottom of the No. 14 coal seam to K3, the water level relationship characteristics between the two aquifers, the high content of nitrate ions, and the relatively high water temperature characteristics are important reference indicators for early warning of Ordovician limestone water disasters using the middle indicator layer.

[0055] S3. Clarify the relevance between the middle indicator layer and the early warning of Ordovician limestone water disasters from three aspects: water level early warning, water quality early warning, and water temperature early warning. Mining practice has proved that there are indeed individual weak points or damaged zones in the coal measures floor of the minefield that receive recharge from the Ordovician limestone water. A typical example is the water-conducting collapse column. Around the weak point or damaged zone, there are abnormal areas of the water level, water temperature, and water chemistry of the middle indicator layer within a certain range. The abnormal area is the early warning area for the risk of Ordovician limestone water inrush.

[0056] S3-1. Water level early warning

[0057] The weak points or fracture zones in the middle indicator layer are mainly water-conducting collapse columns. Around the water-conducting collapse column, a local high water level abnormal diffusion flow field is formed in the middle indicator layer.

[0058] S3-1-1. Hypothetical conceptual model of water-conducting collapse column: (1) The middle indicator layer is an isotropic, laterally infinite, confined, weakly water-rich aquifer; both the middle indicator layer and the Ordovician limestone aquifer are constant head boundaries with equal water levels around. (2) Regularly shaped columnar water-conducting collapse columns are developed in the middle indicator layer; there are no faults or large fractures. (3) The collapse column conducts the Ordovician karst water and has a hydraulic connection with the middle indicator layer, and the water level of the Ordovician limestone aquifer is significantly higher than that of the middle indicator layer. (4) Around the water-conducting collapse column, a two-dimensional planar radial diffusion steady flow field is formed in the middle indicator layer.

[0059] If the collapse column is regarded as an injection well, the relationship between the diffusion head of the middle indicator layer and the distance from the center of the collapse column derived from the Dupuit formula is as follows:

[0060]

[0061] In the formula:

[0062] H is the water level at a certain point within the range affected by the water-conducting collapse column in the middle indicating layer, in m;

[0063] r w is the radius of the collapse column, in m;

[0064] R is the radius of the water level in the middle indicating layer affected by the collapse column, in m;

[0065] h w is the height difference between the bottom of the aquifer and the water level of the Ordovician limestone aquifer, in m;

[0066] h w -H0 is the elevation value of the water level of the middle indicating layer at the center of the collapse column, in m;

[0067] r is the distance from the point with water level H to the center of the collapse column, in m.

[0068] The formula does not include the water injection volume, that is, the recharge water volume Q and K from the concentrated water-conducting channel of the collapse column to the middle indicating layer. This shows that in a steady flow field, as long as the water level in the collapse column and the boundary water head are given, the water head distribution of the collapse column in the middle indicating layer is determined, regardless of the magnitude of the permeability coefficient and the water injection volume.

[0069] S3-1-2. Establish two conceptual models for the collapse column to conduct Ordovician limestone water.

[0070] Model 1: The collapse column penetrates through the water-resisting layers of the roof and floor of the 14th coal seam, conducting the Ordovician limestone water to the aquifer at the floor of the 12th coal seam and the aquifer from the floor of the 14th coal seam to the K3 aquifer. Model 1 has two types. One is that the collapse column does not penetrate through the water-resisting layers of the roof and floor of the 12th coal seam ( Figure 2 ), and the other is that the collapse column penetrates through the water-resisting layers of the roof and floor of the 12th coal seam ( Figure 3 ). In both cases, the water-conducting collapse column directly conducts the Ordovician limestone water to the two aquifers, namely the aquifer at the floor of the 12th coal seam and the aquifer from the floor of the 14th coal seam to the K3 aquifer.

[0071] Model 2: The collapse column only penetrates through the water-resisting layer from the K3 limestone to the G-layer aluminous mudstone, but does not penetrate through the water-resisting layer of the 14th coal seam floor, conducting the Ordovician limestone water to the aquifer from the 14th coal seam floor to the K3 aquifer, causing the water level of the aquifer from the 14th coal seam floor to the K3 aquifer to rise abnormally within a certain range. The abnormally rising water level of the aquifer from the 14th coal seam floor to the K3 aquifer enhances its ability to recharge the aquifer at the floor of the 12th coal seam through the water-resisting layer of the 14th coal seam floor, resulting in an abnormal rise in the water level of the aquifer at the floor of the 12th coal seam ( Figure 4 ).

[0072] S3-1-3. Numerically simulate the flow fields of the two conceptual models:

[0073] Based on the experience of the influence range of collapse columns in Fangezhuang Mine, a numerical simulation model of the main water-bearing (confining) layer section with a diameter of 1000 m on the horizontal plane and a section from the 12th coal seam to 300 m below the Ordovician limestone in the vertical direction was constructed. The elevation of the top of the Ordovician limestone aquifer is -493 m, and the thickness values of the confining layer at the bottom of the 12th coal seam, the aquifer at the bottom of the 12th coal seam, the confining layer at the bottom of the 14th coal seam, the aquifer from the bottom of the 14th coal seam to the K3 aquifer, and the confining layer of the Tangshan Formation mudstone are 20 m, 49 m, 30 m, 29 m, and 64.1 m respectively. The boundary condition is an artificial constant head boundary, with the Ordovician limestone water level at 0 m, the water level of the aquifer at the bottom of the 12th coal seam at -246 m, and the water level of the aquifer from the bottom of the 14th coal seam to the K3 aquifer at -149 m.

[0074] The numerical values of the permeability coefficient and specific yield of each layer were adjusted according to the value range of S2-1, and the diameter of the collapse column was selected as 50 m. The numerical simulation results using the feflow software are as follows:

[0075] The numerical simulation results of Model 1 show that the collapse column causes a water level difference of 130 m with the water level ranging from -110 m to -240 m in the 500 m range centered on the collapse column in the aquifer at the bottom of the 12th coal seam (as Figure 5 ). In the 500 m range centered on the collapse column in the aquifer from the bottom of the 14th coal seam to the K3 aquifer, a water level difference of 60 m with the water level ranging from -90 m to -150 m is formed ( Figure 6 ), showing the characteristic that the water level of the intermediate indicator layer gradually decreases from the collapse column as the center to the surrounding areas.

[0076] The numerical simulation results of Model 2 show that the collapse column causes a water level difference of 50 m with the water level ranging from -190 m to -240 m in the 500 m range centered on the collapse column in the aquifer at the bottom of the 12th coal seam (as Figure 7 ). In the 500 m range centered on the collapse column in the aquifer from the bottom of the 14th coal seam to the K3 aquifer, a water level difference of 90 m with the water level ranging from -60 m to -150 m is formed (as Figure 8 ). It shows the characteristic that the water level of the intermediate indicator layer gradually decreases from the collapse column as the center to the surrounding areas.

[0077] The numerical simulation shows the characteristic that the farther away from the center of the collapse column, the greater the water level difference between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to the K3 aquifer. In Model 1, the water level differences between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to the K3 aquifer in the central area and the peripheral area of the collapse column are 130 m and 60 m respectively. In Model 2, the water level differences between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to the K3 aquifer in the central area and the peripheral area of the collapse column are 50 m and 90 m respectively.

[0078] Since the water level relationship between the Ordovician aquifer and the intermediate indicator layer in the conceptual model is only an ideal one, there is head loss in the actual Ordovician water head during the upward conduction in the collapse column. In numerical simulation, the permeability coefficient in the column can be adjusted to achieve a result close to the actual situation. Therefore, the numerical simulation results show that the water level of the intermediate indicator layer in the center of the collapse column (such as Figure 5 , Figure 6 , Figure 7 , Figure 8 ) is better than the conceptual model established by Dupuit's formula (such as Figure 2 , Figure 3 , Figure 4 )The water level is obviously low.

[0079] The high-pressure Ordovician limestone water at the bottom of the middle indicator layer has good connectivity and sufficient replenishment. Under the action of water pressure, it replenishes the middle indicator layer upward through concentrated water conduction channels such as sinkholes, forming a conical water mound with the concentrated water conduction channel as the center in the middle indicator layer. Therefore, the purpose of early warning of Ordovician limestone water disasters can be achieved by detecting and analyzing the water level of the middle indicator layer.

[0080] S3-2. Water quality warning

[0081] The water quality characteristics of the Orihuite aquifer in the Fangezhuang well field are significantly different from those of the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer. The extremely thick Orihuite aquifer is exposed in a large area to the east and north of the well field. It is strongly recharged by surface water and alluvial water containing nitrate ions, resulting in a relatively high content of nitrate ions in the water of the Orihuite aquifer. The Orihuite water strongly recharges the intermediate indicator layer through the structural weak zone. The hydrochemical characteristics of the Orihuite water spread to the surrounding areas due to the hydrodynamic dispersion phenomenon, causing the water quality of the intermediate indicator layer to be abnormal within a certain range. The water quality abnormality of the intermediate indicator layer can be discovered in advance through exploitation or drilling water gushing, which plays an early warning role in Orihuite water disasters.

[0082] By analyzing the previous water quality test data of Fangezhuang Mine, a comparison chart of the 25th to 75th percentiles of the main water chemical characteristics of the inter-indicator layer and the Ordovician aquifer was drawn, as shown in the figure. Figure 9 Compared with the water in the middle indicator layer, the water in the Aohui aquifer has lower contents of sodium ions, magnesium ions, chloride ions, and sulfate ions. Nitrate ions are common in the Aohui water, but almost non-existent in the water in the middle indicator layer.

[0083] The details are as follows:

[0084] (1) Nitrate ions only exist in the Aohui water, ranging from 3.48 to 11.0 mg / l, while the middle indicator layer does not contain nitrate ions.

[0085] (2) Sodium ions can be used to distinguish the aquifer between the floor of Coal 14 and K3 from the Ordovician limestone water. The 75th percentile value of sodium ions in the Ordovician limestone water is 13.61 mg / l, which is less than the 25th percentile value of 14.76 mg / l of sodium ions in the aquifer between the floor of Coal 14 and K3. When the sodium ion content in the water gushing from the hydrogeological borehole in the aquifer between the floor of Coal 14 and K3 is less than 13.61 mg / l, it indicates that Ordovician limestone water may be involved.

[0086] (3) The content of magnesium ions in the Ordovician limestone water is significantly lower than that in the aquifer water of the floor of Coal 12 and the aquifer between the floor of Coal 14 and K3. The 75th percentile value of magnesium ions in the Ordovician limestone water is 18.71 mg / l, and the 25th percentile values of the aquifer of the floor of Coal 12 and the aquifer between the floor of Coal 14 and K3 are 31.31 mg / l and 32.01 mg / l respectively. When the magnesium ion content in the water gushing from the floor or the exploration borehole in the floor is less than 18.71 mg / l, it indicates that Ordovician limestone water may be involved.

[0087] (4) The content of chloride ions in the Ordovician limestone water is significantly lower than that in the aquifer between the floor of Coal 14 and K3, and slightly lower than that in the aquifer water of the floor of Coal 12. The 75th percentile value of chloride ions in the Ordovician limestone water is 38.55 mg / l, and the median value is 10.59 mg / l. The 25th percentile value of chloride ions in the aquifer between the floor of Coal 14 and K3 is 21 mg / l, and the median value is 29.14 mg / l. When the chloride ion content in the water gushing from the hydrogeological borehole in the aquifer between the floor of Coal 14 and K3 is less than 21 mg / l, it indicates that Ordovician limestone water may be involved.

[0088] (5) The content of sulfate ions in the Ordovician limestone water is significantly lower than that in the aquifer water of the floor of Coal 12 and the aquifer between the floor of Coal 14 and K3. The 75th percentile value of sulfate ions in the Ordovician limestone water is 52.13 mg / l, and the 25th percentile values of the aquifer of the floor of Coal 12 and the aquifer between the floor of Coal 14 and K3 are 43.09 mg / l and 55.07 mg / l respectively. When the sulfate ion content in the water gushing from the floor or the exploration borehole in the floor is less than 43.09 mg / l, it indicates that Ordovician limestone water may be involved.

[0089] (6) The total hardness of the Ordovician limestone water is lower than that of the intermediate indicator layer water. When the total hardness of the water gushing from the floor or the exploration borehole in the floor is less than the 25th percentile value of the total hardness in the aquifer between the floor of Coal 4 and K3, it indicates that Ordovician limestone water may be involved.

[0090] S3-3, Water Temperature Early Warning

[0091] The water temperature of the Ordovician limestone aquifer within the range of the Fanggezhuang minefield is generally higher than that of the aquifer of the floor of Coal 12 and the aquifer between the floor of Coal 14 and K3. The relatively high-temperature Ordovician limestone water rises upward to the intermediate indicator layer through the tectonic weak zone, causing the water temperature of the intermediate indicator layer to rise within a certain range. By judging the abnormal temperature of the water gushing from mining or boreholes, the early warning of Ordovician limestone water disaster can be achieved.

[0092] In the water temperature distribution map of the middle indicator layer, the water temperature observation data of some alluvial aquifers, the 5 coal roof aquifers, the 14 coal floor ~ K3 aquifers, the Ordovician gray aquifers and the 12 coal floor contour lines are filled in. Figure 10 middle.

[0093] The water temperature data of each aquifer in Fangezhuang Mine are collected, such as Figure 11 As shown in the figure, the water temperature characteristics in the six well fields are shown: (1) The water temperature of the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer in the northern wing of the well field gradually increases with the increase of burial depth, and the 14 coal floor ~ K3 aquifer is particularly obvious. (2) The water temperatures of the 12 coal floor aquifer, the 14 coal floor ~ K3 aquifer, and the Ordovician gray aquifer in the adjacent areas are increasing, and the water temperatures of the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer are 7°C and 4.5°C lower than those of the Ordovician gray water, respectively. (3) The water temperature of the Ordovician gray aquifer increases with the increase of burial depth, which is related to the geothermal gradient. (4) The water temperature between the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer in the well field is related to the geothermal gradient. (5) The observation points are arranged from north to south along the strike line of the well field. The depth change is not obvious, but the water temperature of the 14 coal floor ~ K3 aquifer gradually increases, and the temperature difference of the same layer is 5°C. (6) The 12 coal floor aquifer in the third lower mining area is about 400m deeper than the northern wing area, but its water temperature is close to that of the northern wing area. This shows that the water temperature of the aquifer is not only affected by the geothermal gradient of the burial depth, but also related to other factors such as the flow field.

[0094] The overall trend of water temperature in the well field is that it increases with the increase of geothermal gradient, such as the water temperature relationship shown in the above characteristics 1, 2, 3, and 4. However, some characteristics do not conform to or even contradict the geothermal gradient, such as the above characteristics 5 and 6, indicating that the water temperature of the aquifer within the well field is not only related to the geothermal gradient, but also affected by other factors in some areas. There are many factors affecting the water temperature of the aquifer in the well field, and the geothermal gradient is an important factor. The water temperature of the Ordovician aquifer in the well field is 2 to 7 ° C higher than that of the intermediate indicator layer, and there is a trend of gradual increase from north to south. The Ordovician water is introduced into the intermediate indicator layer through the structural weak zone, which can increase the water temperature in the local area, making it easy to distinguish and issue an Ordovician water disaster warning signal.

[0095] S4. Determine the early warning and discrimination indicators of the middle indicator layer Ordovician flood disaster, including water level early warning indicators, water quality early warning indicators and water temperature early warning indicators, as shown in Table 1.

[0096] S4-1. Water level warning indicators

[0097] The water level warning indicators include three items: the water level difference between adjacent areas in the same layer of the intermediate indicator layer, the water level difference between the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer, and the degree to which the water level in the intermediate indicator layer can be drained.

[0098] (1) Water level difference between adjacent areas on the same layer of the middle indicator layer

[0099] The water level of the middle indicator layer is significantly higher than the background value, or the water level at a certain point significantly does not conform to the flow field characteristics of the middle indicator layer area. Ordovician limestone water is connected to the middle indicator layer through concentrated water-conducting channels in the structurally weak zone, forming a conical water mound centered on the structurally weak zone and gradually decreasing towards the surrounding areas in the middle indicator layer.

[0100] The 8 scoring criteria for the warning index of the water level difference between adjacent areas on the same layer of the middle indicator layer are as follows: ① The water level in the northern wing area of the adjacent area on the same layer is 50m to 100m higher; ② The water level in the northern wing area is more than 100m higher; ③ The water level in the third horizontal area is 100m to 200m higher; ④ The water level in the third horizontal area is 200m to 300m higher; ⑤ The water level in the third horizontal area is 300m to 400m higher; ⑥ The water level is more than 400m higher or close to the Ordovician limestone water level; ⑦ The water level significantly does not conform to the regional flow field characteristics; ⑧ There is an obvious closed high water level anomaly in the isohyet. According to the severity of the Ordovician limestone water disaster warning corresponding to each scoring criterion, each index is assigned a value.

[0101] (2) Water level difference between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to K3

[0102] Too large or too small water level difference between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to K3 in the adjacent or the same area is used as an indicator for the warning of Ordovician limestone water disaster.

[0103] The 2 scoring criteria for the warning index of the water level difference between the aquifer at the bottom of the 12th coal seam and the aquifer from the bottom of the 14th coal seam to K3 are as follows: ① The water level difference in the northern wing area is less than 50m or greater than 150m; ② Abnormality of the water level difference in the third horizontal area.

[0104] (3) Drainability of the water level of the middle indicator layer

[0105] The degree to which the water level of the aquifer at the bottom of the 12th coal seam or the aquifer from the bottom of the 14th coal seam to K3 can be drained due to mining or water inrush from boreholes.

[0106] The 1 scoring criterion for the warning index of the drainability of the water level of the middle indicator layer is that the change in the water level of the regional middle indicator layer affected by mining is not obvious. By comparing the water level changes before and after mining or in boreholes, it is comprehensively determined whether it belongs to an area that is easy to be drained, and the index is assigned a value.

[0107] S4-2. Water quality warning index

[0108] The water quality warning index includes 2 items, namely: nitrate ion content, other hydrochemical characteristics.

[0109] (1) Nitrate ion content

[0110] The Ordovician limestone water containing nitrate ions enters the intermediate indicator layer through the tectonic weak zone under the action of water pressure, affecting the water in the intermediate indicator layer that originally did not contain nitrate ions within a certain range, showing the presence of nitrate ions. Whether the water gushing out during the excavation of the hydrogeological boreholes or roadways in the intermediate indicator layer or during the coal face mining contains nitrate ions and the content of nitrate ions can indicate the degree of connection between the intermediate indicator layer and the Ordovician limestone water.

[0111] The nitrate ion content in the Ordovician limestone water is 3.48 - 11.0 mg / l. Considering the dilution situation when the Ordovician limestone water enters the intermediate indicator layer and the possibility of higher nitrate ion content in the Ordovician limestone water that has not been detected yet, the corresponding scoring criteria are formulated for nitrate ions of 0 - 14 mg / l. The five scoring criteria for determining the warning indicators are that the nitrate ion content in the water of the intermediate indicator layer is greater than 0 mg / l and less than 0.5 mg / l, greater than or equal to 0.5 mg / l and less than 3 mg / l, greater than or equal to 3 mg / l and less than 5 mg / l, greater than or equal to 5 mg / l and less than 14 mg / l, and greater than 14 mg / l. Each indicator is assigned a value according to the severity of the Ordovician limestone water disaster warning corresponding to each scoring criterion.

[0112] (2) Other hydrochemical characteristics

[0113] The Ordovician limestone water enters the intermediate indicator layer through the concentrated water-conducting channel of the tectonic weak zone, resulting in a decrease in the content of some ions in the water of the intermediate indicator layer. The contents of sodium ions, magnesium ions, chloride ions, sulfate ions and total hardness in the water gushing out during the excavation of the hydrogeological boreholes or roadways in the intermediate indicator layer or during the coal face mining are relatively low.

[0114] According to the results of S3-2, the 75th percentile values of the contents of sodium ions, magnesium ions, chloride ions, sulfate ions and total hardness of the Ordovician limestone water are respectively selected as the standards. The five scoring criteria for determining the warning indicators are that the sodium ion content is less than 13.61 mg / l, the magnesium ion content is less than 18.71 mg / l, the chloride ion content is less than 21 mg / l, the sulfate ion content is less than 43.09 mg / l, and the total hardness is less than 132.85 mg / l. Each indicator is assigned a value according to the severity of the Ordovician limestone water disaster warning corresponding to each scoring criterion.

[0115] S4-3. Water temperature warning indicator

[0116] The water temperature warning indicator includes one item, which is the water temperature difference of the same layer in the intermediate indicator layer (referred to as the water temperature difference).

[0117] The Ordovician limestone water with a higher temperature is guided by the concentrated water-conducting channel in the weak tectonic zone under the action of water pressure to the intermediate indicator layer, resulting in an increase in the water temperature of the intermediate indicator layer within a certain range. According to the water temperature distribution law of the Ordovician limestone aquifer and the intermediate indicator layer in the Fan'gezhuang minefield, the four scoring criteria for this warning index are as follows: the water temperature is 0.5 °C or less higher in the area except for the south four and south five of the third level; the water temperature is 0.5 to 1 °C (inclusive) higher in the area except for the south four and south five of the third level; the water temperature is 1 to 2 °C (inclusive) higher in the area except for the south four and south five of the third level; the water temperature is 2 °C or higher higher in the area except for the south four and south five of the third level; the water temperature is 3 °C or higher higher in the south four and south five areas of the third level. According to the severity of the Ordovician limestone water disaster warning corresponding to each scoring criterion, each index is assigned a value.

[0118] Table 1 Value Table of Ordovician Limestone Water Disaster Warning Index by Intermediate Indicator Layer Method

[0119]

[0120] S5. Establish an Ordovician limestone water disaster warning discrimination system using the comprehensive scoring method and the fuzzy comprehensive evaluation method respectively.

[0121] (1) Warning discrimination system of comprehensive scoring method

[0122] According to the single-warning score of the warning index in S4, score each warning index of the area to be evaluated. According to different comprehensive warning score values, determine the Ordovician limestone water disaster warning levels of the area to be evaluated as five levels: first, second, third, fourth, and no warning. See Table 2 below for details:

[0123] Table 2 Ordovician Limestone Water Disaster Warning Risk Level Table

[0124]

[0125] (2) Fuzzy comprehensive evaluation warning discrimination system

[0126] According to the Ordovician limestone water disaster warning discrimination index determined in S4, it is determined that the index set U contains a total of 6 items, specifically as follows:

[0127] U = (u1, u2, u3, u4, u5, u6)

[0128] Where: u1 - water level difference between adjacent areas of the same layer of the intermediate indicator layer;

[0129] u2 - water level difference between the aquifer at the bottom of the 12th coal seam and the aquifers from the bottom of the 14th coal seam to K3;

[0130] u3 - degree of water level drawdown of the intermediate indicator layer;

[0131] u4 - nitrate ion content;

[0132] u5 - other hydrochemical characteristics;

[0133] u6——Water temperature difference.

[0134] Table 3 Judgment matrix table of fuzzy comprehensive analysis method

[0135]

[0136] Compare the 6 warning indicators in pairs, assign values to the comparison results of the two according to the importance degree of the warning indicators and their corresponding score situations, and form a judgment matrix with the obtained results, denoted as A, as shown in Table 3.

[0137] According to the judgment matrix table, construct the weight value expression of each discriminant index as W = (0.3, 0.1, 0.15, 0.3, 0.05, 0.1).

[0138] The comment set V of the risk degree of each warning index factor = (Level 1 warning, Level 2 warning, Level 3 warning, Level 4 warning, No warning). Investigate and score the warning risk level of each warning index. The water hazard warning risk degree of the warning risk level is consistent with the comprehensive analysis method. Ensure that the total score value of each warning risk level is 1 during scoring. Use the SPSSAU system to select the weighted average type calculation method for fuzzy comprehensive analysis, and finally give the Ordovician limestone water hazard warning evaluation result.

[0139] S6. Evaluate the high-risk area of Ordovician limestone water hazard in the mine field using the comprehensive scoring method warning discriminant system and the fuzzy comprehensive evaluation warning discriminant system. Score each index using the comprehensive scoring method, calculate the comprehensive warning score, and determine the warning level; use fuzzy comprehensive evaluation to score the warning risk degree of each warning index, and ensure that the total score value of each warning level is 1; compare the warning results of the comprehensive scoring method and the fuzzy evaluation method to determine the final evaluation conclusion.

[0140] Taking the 2298, 208 high water level anomaly areas and the North Second Strip area as examples, substitute the data of the identified anomaly areas into the warning discriminant system to verify and explain the warning process:

[0141] S6-1. Use the comprehensive scoring method to conduct Ordovician limestone water hazard warning for the mine. The scoring results of each warning discriminant index are shown in Tables 4, 5, and 6 respectively, and the comprehensive evaluation result is shown in Table 7. In the scoring table, the Roman letters in the column of "Warning discriminant conditions, scoring standard number" correspond to the warning index numbers in Table 1, and the lowercase Chinese pinyin after the Roman letters refers to the scoring standard numbers in Table 1. If there is "x" or "0" after the Roman letters, it means that there is no actual data to confirm this warning index or this warning index does not give a warning. Using the comprehensive scoring method to conduct Ordovician limestone water hazard warning for the mine, the results show that there is a Level 1 Ordovician limestone water hazard warning in the 2298 high water level area and the 208 high water level area, and there is a Level 4 Ordovician limestone water hazard warning in the North Second Strip area.

[0142] Table 4 Comprehensive Scoring Table of Ordovician Limestone Water Disaster Early Warning Discrimination System for the Intermediate Indicator Layer in the 2298 High Water Level Abnormal Area

[0143]

[0144]

[0145]

[0146] Table 5 Comprehensive Scoring Table of Ordovician Limestone Water Disaster Early Warning Discrimination System for the Intermediate Indicator Layer in the 208 High Water Level Abnormal Area

[0147]

[0148]

[0149] Table 6 Comprehensive Scoring Table of Ordovician Limestone Water Disaster Early Warning Discrimination System for the Intermediate Indicator Layer in the North Second Strip Area

[0150]

[0151]

[0152] Table 7 Evaluation Results Table of Ordovician Limestone Water Disaster Early Warning in the Mine Field by the Comprehensive Scoring Method

[0153]

[0154] S6-2. Using the fuzzy comprehensive evaluation method, conduct a fuzzy comprehensive evaluation on the 2298, 208 high water level abnormal areas and the North Second Strip Area (Table 8).

[0155] Table 8 Value Table of Fuzzy Comprehensive Evaluation Index for Ordovician Limestone Water Disaster Early Warning in the Mine Field

[0156]

[0157] Adopt the weighted average type calculation method selected by the SPSSAU system for fuzzy comprehensive evaluation. The membership degree of the first-level early warning in the 2298 high water level area is the highest, with a membership degree value of 0.9. The membership degree of the first-level early warning in the 208 high water level area is the highest, with a membership degree value of 1.0. The membership degree of no early warning in the North Second Strip Area is the highest, with a membership degree value of 0.9. The evaluation results are basically consistent with the comprehensive scoring method (Table 9, Figure 12 )), and there are only slight differences in the evaluation results of the North Second Strip Area.

[0158] Table 9 Fuzzy Comprehensive Evaluation Results Table of Ordovician Limestone Water Disaster Early Warning in the Mine Field

[0159]

[0160] The present invention also provides the application of the intermediate indication layer method for Ordovician limestone water disaster early warning system, which mainly includes three aspects, namely the Ordovician limestone water disaster risk early warning in the driving roadway (referred to as the driving roadway early warning), the Ordovician limestone water disaster risk assessment of the floor of the mining face (referred to as the water disaster risk assessment of the mining face), and the Ordovician limestone water disaster risk assessment of the advanced exploration results of the regional floor (referred to as the water disaster risk assessment of the regional floor). The driving roadway early warning refers to analyzing the water temperature, water quality, and water level of the water inrush in the driving roadway, substituting into the early warning discrimination index system, and giving the early warning level and risk degree. The water disaster risk assessment of the working face refers to carrying out drilling and water discharge test projects for the intermediate indication layer during the driving process and before the mining of the coal mining face, substituting the exploration results into the early warning discrimination index system, and giving the early warning level and risk degree. The regional water disaster risk assessment refers to drilling and exploring the intermediate indication layer in a certain area through the existing roadway, substituting the exploration results into the early warning discrimination index system, and giving the early warning level and risk degree.

[0161] (1) The sudden water inrush in the roadway during the driving process plays a crucial role in the early warning of Ordovician limestone water disasters. When the roadway approaches the vertical water-conducting structure that conducts the Ordovician strong aquifer, sudden water inrush occurs. The accurate judgment of the water source of the sudden water inrush is the key to the early warning of Ordovician limestone water disasters.

[0162] In 2012, when the 3094 coal haulage roadway was driven to 92 - 96 m, water seepage occurred on the right side roof and rib of the roadway, with a water volume of 0.02 m³ / min. The advanced exploration holes drilled showed that the water level of the coal measure strata in this area was -137.88 m, about 138 m higher than the normal water level of the 12th coal floor aquifer in this area. The water temperature was 21 °C, 3 °C higher than the water temperature of the 12th coal floor aquifer in this area, which was 18 °C. The water quality test showed that the content of nitrate ions was 3.48 mg / l, the content of sodium ions was 19.69 mg / l, the content of chloride ions was 142.25 mg / l, and almost no magnesium ions were contained.

[0163] The comprehensive scoring method is used for the Ordovician limestone water disaster early warning evaluation, which meets the early warning requirements of four early warning indicators: the water level difference between adjacent areas of the same layer of the intermediate indication layer, the content of nitrate ions, other hydrochemical characteristics, and the water temperature difference. The early warning scores of the four indicators are 6, 6, 1, and 10 respectively, and the comprehensive early warning score is 23 points, which is a first-level early warning (Table 10).

[0164] Table 10 Early warning evaluation form of the comprehensive scoring method for the driving roadway early warning

[0165]

[0166] The fuzzy comprehensive evaluation method is used for the Ordovician limestone water disaster early warning evaluation, and the values of each evaluation index are shown in Table 11. The SPSSAU system is used to select the weighted average type calculation method for fuzzy comprehensive evaluation (Table 12). The membership degree of the first-level early warning is 1, indicating a first-level early warning of Ordovician limestone water disasters, which is consistent with the result of the comprehensive scoring method. After comprehensive research and judgment, in order to avoid the occurrence of water disaster accidents, it was decided to abandon this roadway.

[0167] Table 11 Value Table of Fuzzy Comprehensive Evaluation Index for Early Warning of Driving Roadway

[0168]

[0169] Table 12 Result Table of Fuzzy Comprehensive Evaluation for Early Warning of Driving Roadway

[0170]

[0171] (2) In the risk assessment of Ordovician limestone water disaster in the floor of the coal mining face, the intermediate indicator layer method is used to guide the geophysical exploration, drilling, chemical exploration and water discharge test work of Ordovician limestone water disaster in the working face of the complex hydrogeological conditions area. According to the exploration results, the water disaster early warning discrimination system is used to evaluate and early warn the Ordovician limestone water disaster situation in the working face, effectively solving the problems of exploration and evaluation of Ordovician limestone water disaster in the working face.

[0172] The hydrogeological conditions in the area of Working Face 2120(4) in the northern wing of Fangezhuang Mine are complex. It is located in the area where collapse columns are developed, adjacent to No. 12 collapse column, No. 208 high water level anomaly area and North Second Belt area. The water inrush coefficient method is selected to evaluate the water disaster in the floor of the working face. The calculation results of the water inrush coefficient show (Table 13) that the water inrush coefficient of the Ordovician limestone aquifer in this working face area meets the requirement of the "Coal Mine Water Prevention and Control Rules" that the water inrush coefficient is generally not greater than 0.06 MPa / m, and it can be mined under pressure normally. However, the possible vertical water-conducting structure of the collapse column also threatens the safe mining of the working face.

[0173] The comprehensive scoring method is used for the early warning evaluation of Ordovician limestone water disaster. Among them, there are two warning indicators, namely: the water level difference between adjacent areas of the same layer of the intermediate indicator layer, and other hydrochemical characteristics. For the water level difference between adjacent areas of the same layer of the intermediate indicator layer, the maximum water level differences between the observation wells of the aquifers at the bottom of Coal Seam 12 and the aquifers from the bottom of Coal Seam 14 to K3 are 66 m and 51 m respectively, meeting the discrimination condition of this discrimination index "the water level in the northern wing area is 50 to 100 m higher", and the warning score of this index is 1 point. For the other hydrochemical characteristics index, since the contents of Na + 、Mg 2+ 、Cl - ions in the aquifers at the bottom of Coal Seam 12 and K3 limestone aquifer are relatively low, the warning score of this index is 1.5 points. The comprehensive early warning score of Working Face 2120(4) is 2.5 points, and there is no early warning of Ordovician limestone water disaster (Table 13). The thickness of the floor water-resisting layer meets the relevant requirements of the water inrush coefficient. The comprehensive evaluation shows that this working face is not threatened by the floor water disaster, and this working face has achieved safe mining in 2018.

[0174] Table 13 Early Warning Evaluation Table of Comprehensive Scoring Method for Exploration of Water Disaster in the Floor of the Working Face

[0175]

[0176] The fuzzy comprehensive evaluation method is adopted for the early warning evaluation of Ordovician limestone water hazards, and the values of each evaluation index are shown in Table 14. The weighted average type calculation method is selected by the SPSSAU system for fuzzy comprehensive analysis (Table 15), indicating that the membership degree of no early warning is 1, which is consistent with the result of the comprehensive scoring method. The safe mining of this working face has been realized.

[0177] Table 14 Value Table of Fuzzy Comprehensive Evaluation Indexes for the Exploration of Floor Water Hazards in the Working Face

[0178]

[0179] Table 15 Result Table of Fuzzy Comprehensive Evaluation for the Exploration of Floor Water Hazards in the Working Face

[0180]

[0181] (3) The exploration of regional floor water hazards is an important application of the middle indicator layer method used by Fangezhuang Mine to prevent and control floor water hazards. The -620 level of Fangezhuang Mine is the deepest mining level of the mine, and the Ordovician limestone water pressure borne by its floor is significantly higher than that of the mined areas. Coupled with the possible vertically conductive structures existing in it, the threat to the safe mining of the mine is greater.

[0182] The comprehensive scoring method is adopted for the early warning evaluation of Ordovician limestone water hazards. There are no early warning indicators for Ordovician limestone water hazards in all indicators, and there is no early warning for Ordovician limestone water hazards.

[0183] Table 16 Value Table of Fuzzy Comprehensive Evaluation Indexes for the Advanced Exploration of Underground Regional Floor

[0184]

[0185] Table 17 Result Table of Fuzzy Comprehensive Evaluation for the Advanced Exploration of Underground Regional Floor

[0186]

[0187] The fuzzy comprehensive evaluation method is adopted for the early warning evaluation of Ordovician limestone water hazards, and the values of each evaluation index are shown in Table 16. The weighted average type calculation method is selected by the SPSSAU system for fuzzy comprehensive analysis (Table 17), indicating that the membership degree of no early warning is 1, which is consistent with the result of the comprehensive scoring method. The safe mining of 2 working faces of No. 12 coal seam has been realized in this area at present.

[0188] Finally, it should be noted that: the above-listed are only the preferred embodiments of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and its equivalent technologies, they should all be considered as the protection scope of the present invention.

Claims

1. An intermediate indicator layer FAO ash water disaster early warning method, characterized in that: The steps include: S1. Collect the geological and hydrogeological exploration data of the well field, obtain the regional geological and hydrogeological conditions, and determine the intermediate indicator layer according to the stratigraphic structure and lithological combination characteristics from the mineable coal seam to the top interface of the Ordovician ash; S2. Analyze the stratigraphic structure and hydrogeological characteristics of the Ordovician gray aquifer and the intermediate indicator layer, and analyze the differences in water level, water quality, water temperature and hydrogeological characteristics and the temporal and spatial distribution of the differences; S3. Clarify the relevance of the intermediate indicator layer to the Aohui flood warning from three perspectives: water level warning, water quality warning and water temperature warning; S4. Determine the early warning and discrimination indicators of the middle indicator layer Ordovician flood disaster, including water level early warning indicators, water quality early warning indicators and water temperature early warning indicators, and establish scoring standards for each early warning and discrimination indicator; S5. Use comprehensive scoring method and fuzzy comprehensive evaluation method to establish the early warning and discrimination system of Ordovician flood disaster in the middle indicator layer; S6. Use the comprehensive scoring method early warning judgment system and the fuzzy comprehensive evaluation early warning judgment system to evaluate the high-risk areas of Ordovician flooding in the mining area.

2. The intermediate indicator layer FAO ash water hazard early warning method according to claim 1 is characterized in that: S3 When determining the correlation between the intermediate indicator layer and the Ordovician limestone water hazard, a conceptual model of the mine collapse column directing the deep Ordovician limestone water to the upper part is established, and the feflow numerical simulation software is used to simulate the influence range of the water level, water temperature and water quality characteristics when the water-conducting collapse column directs the Ordovician limestone water to the intermediate indicator layer under the conditions of the lithology and structure of the coal mine, the hydrogeological parameters of the Ordovician limestone aquifer and the intermediate indicator layer.

3. The intermediate indicator layer method of Ao ash water disaster early warning method according to claim 2 is characterized in that: If the water-conducting collapse column is regarded as an injection well, after the Ordovician limestone water is guided up to the middle indicator layer through the collapse column, the relationship between the diffusion head of the middle indicator layer and the distance from the center of the collapse column satisfies the Dupuit formula. On this basis, a conceptual model is established that can reflect the flow field characteristics of the surrounding middle indicator layer under the influence of the water-conducting collapse column.

4. The intermediate indicator layer method of Aohui water disaster early warning method according to claim 2 is characterized in that: Compared with the water quality of the Aohui aquifer and the intermediate indicator layer, the contents of sodium ion, magnesium ion, chloride ion and sulfate ion in the Aohui water are relatively low. Nitrate ion is prevalent in the Aohui water, but almost non-existent in the intermediate indicator layer water.

5. The intermediate indicator layer FAO ash water hazard early warning method according to claim 2 is characterized in that: The water temperature of the Ordovician gray aquifer is higher than that of the middle indicator layer. By judging the temperature anomaly of the exploited water or the drilling water, it can play the role of early warning of Ordovician gray water disasters.

6. The intermediate indicator layer FAO ash water hazard early warning method according to claim 1 is characterized in that: The S4 water level warning indicators include the water level difference between adjacent areas in the same layer of the intermediate indicator layer, the water level difference between the two intermediate indicator layers, and the degree of drainage of the water level in the intermediate indicator layer; Water quality warning indicators in S4 include nitrate ion content and other water chemical characteristics. Other water chemical characteristics include sodium ion, magnesium ion, chloride ion, sulfate ion content and total hardness; The water temperature warning indicator in S4 is the water temperature difference in the same layer of the middle indicator layer.

7. The intermediate indicator layer FAO ash water hazard early warning method according to claim 1 is characterized in that: The comprehensive scoring method warning identification system in S5 scores each warning indicator of the evaluation area according to the single warning score of the warning indicator. According to different comprehensive warning scores, the warning level of the Ordovician flood disaster in the evaluation area is determined as one, two, three, four and no warning.

8. The intermediate indicator layer FAO ash water hazard early warning method according to claim 1 is characterized in that: Fuzzy comprehensive evaluation method early warning judgment system in S5: According to the Aohui flood warning identification index determined in S4, the index set U is determined to contain 6 items, as follows: U=(u1,u2,u3,u4,u5,u6) Where: u1——the water level difference between adjacent areas in the same layer of the middle indicator layer; u2——the water level difference between the 12 coal floor aquifer and the 14 coal floor ~ K3 aquifer; u3——the degree of drainage of water level in the middle indicator layer; u4——nitrate ion content; u5——other water chemical characteristics; u6——water temperature difference; The six early warning indicators are compared in pairs, and the comparison results are assigned values ​​according to the importance of the early warning indicators and their corresponding scores, and the obtained results form a judgment matrix; According to the judgment matrix table, construct the weight value expression of each judgment index; The risk level of each early warning indicator factor is evaluated as a set of comments V = (level 1 warning, level 2 warning, level 3 warning, level 4 warning, no warning); Investigate and score the early warning risk level of each early warning indicator, and ensure that the total score of each early warning level is 1; The SPSSAU system was used to select the weighted average calculation method for fuzzy comprehensive analysis, and finally the early warning evaluation results of the Ordos gray water disaster were given.

9. The intermediate indicator layer FAO ash water hazard early warning method according to claim 1, characterized in that: In S6, the warning results of the comprehensive scoring method and the fuzzy evaluation method are compared to determine the final evaluation conclusion.

10. An application of the intermediate indicator layer method of Aoshield water disaster early warning method according to any one of claims 1 to 9, characterized in that: The intermediate indicator layer method Ordovician lime water hazard early warning method is applied in Ordovician lime water hazard risk warning of excavation tunnels, Ordovician lime water hazard risk assessment of mining face floor and Ordovician lime water hazard risk assessment of regional floor advance exploration results.

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