A method for distinguishing water-retaining mining for in-situ protection of floor pressure water

Abstract

The present invention discloses a water-preserving mining discrimination method for in-situ protection of floor confined water, comprising the following steps: determining the average distance between the floor of the mining coal seam and the aquifer, the average thickness of the aquifer, the average permeability, the length of the working face and the length of the advancement distance; testing the average depth of the crushing zone of the mining floor, the average thickness and the average permeability of each rock layer below the crushing zone, and obtaining the equivalent permeability; testing and statistically analyzing the water pressure of the confined aquifer and determining the target water pressure; calculating the amount of water resources allowed to be lost during coal mining; determining the critical equivalent permeability coefficient; comparing the equivalent permeability with the critical equivalent permeability, and comparing the calculated water inflow with the safe water inflow of the working face; and finally determining the feasibility of water-preserving mining for in-situ protection of floor confined water. Based on the dynamic water storage and release characteristics of the confined aquifer and the overall water-blocking performance of the effective rock layer of the mining floor, the present invention provides a water-preserving mining discrimination method for in-situ protection of floor confined water, which is simple to operate and has strong on-site applicability.

Description

Technical Field

[0001] The invention relates to the technical field of water-preserving mining, and in particular to a water-preserving mining identification method for in-situ protection of bottom plate pressure water. Background Art

[0002] Water-conserving mining has always been one of the hot issues of academic concern, and the concept and technology of water-conserving mining are becoming more and more perfect and mature. For the in-situ protection of floor water, a technical method with the height of water-conducting fracture zone, the stability of key water-blocking layer or water-blocking layer or group as evaluation indicators has been initially formed. Chinese scholars have achieved rich research results in the prevention and control of floor pressurized water, and proposed floor water inrush theory and evaluation methods by analyzing the deformation and damage characteristics of the mining floor, the depth of crack development, etc., which effectively guided the safe production of mines. Such as "vulnerability index method, five-chart double coefficient method, water inrush coefficient method", etc. Scholars have shifted from "water hazard prevention and control" of floor pressurized water to "in-situ water-conserving mining" of floor pressurized water, but the relevant research results have the following shortcomings:

[0003] ① Existing research pays less attention to the in-situ protection of floor water, but more attention to safe mining, and proposes corresponding resistance enhancement technical parameters and early warning technologies. Water conservation mining and safe mining should be coordinated to make full use of the complementary mode of the two.

[0004] ② The existing methods such as the stability of the key floor waterproofing layer and the water inrush coefficient method can provide a certain reference for the in-situ protection of floor water, but they do not take into account the differences and heterogeneity of the hydraulic properties of the rock formations. They should be quantitatively analyzed from the overall water-blocking performance of the effective waterproofing layer to directly provide a method for distinguishing water-preserving mining for in-situ protection of floor pressure water.

[0005] ③ Not only should we pay attention to the stability of the confined aquifer within the mining range, but also ensure the stability of the confined aquifer outside the mining range, that is, do not destroy the recharge of the confined aquifer through the mining range, and eliminate the situation where the confined aquifer outside the impact area has only discharge but no recharge. The traditional critical condition that the recharge of the aquifer within the mining range is equal to the leakage of the working face should not be used. Furthermore, since the confined aquifer is generally thicker and the recharge is more sufficient, the leakage of the working face is larger, which will seriously affect the safe recovery of the working face. The in-situ protection of bottom water should have its particularity.

[0006] Chinese invention patent: The announcement number is "CN110749533B", and the name is "A method for distinguishing water-retaining coal mining based on the thickness of the equivalent impermeable layer". The patent discloses a method for distinguishing water-retaining coal mining based on the thickness of the equivalent impermeable layer. The specific steps are: determine the thickness of each rock layer of the overburden Total thickness of overburden ;Test the permeability coefficient of each rock layer after mining ; Calculate the equivalent permeability of the overburden rock ; Determine the depth of the aquifer and supply ; Determine the water head height of the aquifer after mining; Calculate the critical equivalent aquiclude thickness that can achieve water-saving coal mining ; The critical equivalent aquiclude thickness The total thickness of all rock layers from the coal seam roof to the aquiclude The feasibility of water-preserving mining of coal seams is finally determined by comparison. This technical solution is based on the changes in the hydraulic characteristic parameters of the overall permeability coefficient and leakage volume of the overburden before and after mining. It provides a direct method for determining the feasibility of water-preserving mining protected by the roof aquifer from the essence of the rock layer's water-impermeability. It is more accurate, quick, and has strong practical application on site. However, this technical solution does not take into account the influence of the broken zone, that is, the broken zone has little effect on the water-blocking performance of the rock layer, but it will reduce the hydraulic gradient from the aquifer to the working face, resulting in an increase in the critical equivalent water-blocking thickness. It does not take into account the differences and heterogeneity of the hydraulic properties of the rock layer, that is, the permeability coefficients of different positions of the bottom plate are different due to their own hydraulic properties and stress states. It does not take into account the stability of the aquifer in the area outside the mining influence, and only assumes the boundary condition that the infiltration of the aquifer is equal to the recharge. The downstream aquifer outside the mining influence range will have no recharge. In addition, if the recharge of the aquifer is large, complete infiltration will affect the safe recovery of the working face. Summary of the invention

[0007] In order to solve the problem that the above-mentioned prior art does not consider the differences and heterogeneity of rock formation hydraulic properties, does not consider the stability of aquifers, and only assumes the boundary condition that the infiltration amount of aquifers is equal to the recharge amount, which will affect the safe mining of the working face, the present invention proposes a water-preserving mining identification method for in-situ protection of bottom plate pressure water, which fully considers the differences and heterogeneity of rock formation hydraulic properties, takes into account the two working modes of water-preserving mining and safe mining, and has a simple identification method, high operability, and strong on-site applicability.

[0008] The present invention is achieved through the following technical solution: comprising the following steps:

[0009] S1. Determine the average distance between the bottom of the mining coal seam and the aquifer , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance ;

[0010] S2. Average depth of the broken zone of the bottom plate of the mining coal seam obtained by detection , the average thickness of each rock layer below the fracture zone , Average permeability of each rock layer below the fracture zone and the equivalent permeability of the layered heterogeneous floor ;

[0011] S3, detection and statistics of the total time is , water pressure in the confined aquifer at different time periods , determine the target water pressure of the target confined aquifer ; The water pressure of the confined aquifer obtained by the test and target water pressure Compare and get the water pressure exceeding the target Water pressure in confined aquifers and water pressure in confined aquifers Exceeding target water pressure Time ;

[0012] S4: Target water pressure obtained according to step S3 With water pressure and time , substitute into the formula , and the amount of water resources lost during coal mining can be obtained ; In the formula, is the hydrodynamic viscosity coefficient, in Pa·s;

[0013] S5, the water pressure of the confined aquifer obtained in step S3 and the amount of water resources lost during coal mining obtained in step S4 , substitute into the formula , and the critical equivalent permeability coefficient of the impermeable rock layer in the mining coal seam floor is obtained ; In the formula, is the total detection time, in days; is the critical equivalent permeability coefficient of the impermeable rock layer at the bottom of the mining coal seam, the unit is D; is the water pressure on the working surface, in MPa;

[0014] S6. Determine the feasibility of water conservation mining for in-situ protection of floor pressure water;

[0015] S61, the equivalent permeability of the layered heterogeneous base plate obtained in step S2 and the critical equivalent permeability coefficient of the impermeable rock layer of the mining coal seam floor obtained in step S5 For comparison, if > , then after coal seam mining, it is impossible to achieve in-situ protection of floor pressure water; if ≤ , then execute step S62;

[0016] S62, the equivalent permeability of the layered heterogeneous base , Average depth of the broken zone of the mining coal seam floor , Average distance between the bottom of the mining coal seam and the aquifer , working surface length , Advance distance length and water pressure in confined aquifers , substitute into the formula , and obtain the water inflow per unit time within the total time range If it does not exist ≥ If the continuous time is more than 5 days, the bottom plate pressure water in-situ protection can be achieved; if there is ≥ If the continuous time is more than 5 days, the bottom plate pressure water in-situ protection cannot be achieved. The amount of water inflow required to ensure safe mining at the working face, in m 3 / sky.

[0017] Furthermore, step S2 includes the following steps:

[0018] S21, length of working surface and the length of the advancing distance Arrange A×B drilling points within the mining range to obtain the depth of several bottom plate fracture zones, the thickness of each rock layer below the fracture zone, and the permeability;

[0019] S22, averaging the depths of several floor crushing zones, the thicknesses of various rock layers, and the permeability detected in step S21 to obtain the average depth of the floor crushing zone of the mining coal seam , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone ;

[0020] S23, the average depth of the broken zone of the mining coal seam floor obtained in step S22 , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone , substitute into the formula , the equivalent permeability of the layered heterogeneous base is obtained ; In the formula, , The number of rock layers below the fracture zone.

[0021] Furthermore, in step S1, the average distance between the bottom plate of the mining coal seam and the aquifer is obtained by drilling on site and consulting the geological and hydrogeological exploration report of the mine owner and the mine development plan. , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance .

[0022] Furthermore, in step S2, the depth detection of the bottom plate broken zone is mainly based on on-site water pressure test, supplemented by parallel electrical method. The thickness of each rock layer below the broken zone is obtained by on-site drilling, and the average thickness of each rock layer below several broken zones is obtained by averaging the thickness of each rock layer below the broken zone. , the average permeability of each rock layer below the fracture zone The average value is obtained by testing the water pressure during drilling.

[0023] Furthermore, in step S21 A and B The values ​​of are 10 and 5 respectively, and the distances between the strike and dip measuring points of the working face are , .

[0024] Furthermore, the total time of detection in step S3 is One year is a cycle, and different time periods are divided into four quarters.

[0025] Furthermore, the target water pressure in step S3 is The determination method is: solve the average water pressure of the confined water in spring and autumn, and take the maximum value as the target water pressure .

[0026] Furthermore, in step S4, the water pressure exceeding the target water pressure in the confined aquifer state in summer and winter is counted. Water pressure in confined aquifers and time .

[0027] Furthermore, in step S5, the critical equivalent permeability coefficient of the impermeable rock layer at the bottom of the mining coal seam is calculated. When the amount of water lost from coal mining is allowed to Averaged over every day of the year; working surface water pressure The value is obtained through field testing.

[0028] Furthermore, in step S62 The value is 1000m 3 / sky.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The identification method provided by the present invention not only focuses on the stability of the aquifer within the mining range, but also ensures the stability of the aquifer outside the mining range, that is, it does not destroy the recharge of the aquifer through the mining range, and eliminates the situation where the aquifer outside the mining range has only discharge but no recharge, and the judgment conclusion is more accurate.

[0031] 2. Based on the dynamic water storage and release characteristics of the confined aquifer and the overall water-blocking performance of the mining bottom plate to effectively block the rock formation, the present invention provides a water-preserving mining identification method for in-situ protection of bottom plate confined water. The method is easy to operate and has strong on-site applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the overall flow chart of the discrimination method of the present invention.

[0033] Figure 2 This is a schematic diagram of the structural damage of the waterproof rock layer in the bottom plate after mining and the layout of measuring points.

[0034] Figure 3 is the water pressure of the confined aquifer in different time periods in Example 1 With target water pressure Point and line chart.

[0035] Figure 4 The water inflow per unit time within the total time range of Example 1 Point and line chart. DETAILED DESCRIPTION

[0036] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the present invention provides a method for distinguishing water conservation mining for in-situ protection of floor pressure water, and the specific steps are as follows:

[0038] Step S1: Drilling on site and consulting the geological and hydrogeological exploration report and the mine development plan to obtain the average distance between the bottom plate of the mining coal seam and the aquifer. , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance .

[0039] Step S2: Detect and obtain the average depth of the broken zone of the mining coal seam floor , the average thickness of each rock layer below the fracture zone , Average permeability of each rock layer below the fracture zone and the equivalent permeability of the layered heterogeneous floor .

[0040] Step S21: Length of working surface and the length of the advancing distance A×B drilling points are arranged within the mining range to obtain the depth of several bottom plate crushing zones, the thickness of each rock layer below the crushing zone, and the permeability.

[0041] Step S22, average the depths of several floor fracture zones, the thickness of each rock layer and the permeability detected in step S21 to obtain the average depth of the floor fracture zone of the mining coal seam , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone .

[0042] Step S23: The average depth of the broken zone of the mining coal seam floor obtained in step S22 is , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone , substitute into the formula , the equivalent permeability of the layered heterogeneous base is obtained .

[0043] In the formula, is the average distance between the bottom of the mining coal seam and the aquifer, in meters; is the average depth of the broken zone of the mining coal seam floor, in m; is the average thickness of each rock layer below the fracture zone, in m; is the average permeability of each rock layer below the fracture zone, with the unit of D, i.e. Darcy; , The number of rock layers below the fracture zone.

[0044] As a preferred method, the depth detection of the bottom plate broken zone is mainly based on on-site water pressure test, supplemented by parallel electrical method to ensure the rationality of the test results. The thickness of each rock layer below the broken zone is obtained by on-site drilling, and the average thickness of each rock layer below several broken zones is calculated to obtain the average thickness of each rock layer below the broken zone. , the average permeability of each rock layer below the fracture zone The average value is obtained by testing the water pressure during drilling.

[0045] As a preference, the length of the working surface and the length of the advancing distance Arrangement within the scope of the mining operation A × B Drilling points, A and B The values ​​of are 10 and 5 respectively, and the distances between the strike and dip measuring points of the working face are , .

[0046] Step S3: Detect and count the total time , water pressure in the confined aquifer at different time periods , determine the target water pressure of the target confined aquifer The water pressure of the confined aquifer is and the target water pressure of the target confined aquifer Compare and get the water pressure exceeding the target Water pressure in confined aquifers and water pressure in confined aquifers Exceeding target water pressure Time The objective of the target confined aquifer is to achieve in situ water retention.

[0047] As a preference, the total detection time One year is taken as one cycle, and different time periods are divided into four quarters. Target water pressure of the target confined aquifer The determination method is: considering that the water pressure of the confined aquifer in spring and autumn is relatively stable, the average water pressure of the confined water in spring and autumn is solved, and the maximum value is taken as the target water pressure .

[0048] Step S4: Target water pressure obtained in step S3 The water pressure in the confined aquifer exceeds the target water pressure. and time , substitute into the formula , and the amount of water resources lost during coal mining can be obtained .

[0049] In the formula, is the target water pressure of the target confined aquifer, in MPa; The water pressure of the confined aquifer that exceeds the target water pressure, in MPa; The water pressure in the confined aquifer exceeds the target water pressure. The time, in days; The amount of water resources allowed to be lost during coal mining, in m 3 ; is the hydrodynamic viscosity coefficient, in Pa·s.

[0050] Preferably, the water pressure of the confined aquifer exceeds the target water pressure. and time The measurement range is based on the state of confined aquifers in summer and winter.

[0051] Step S5: The water pressure of the confined aquifer obtained in step S3 and the amount of water resources lost during coal mining obtained in step S4 , substitute into the formula , and the critical equivalent permeability coefficient of the impermeable rock layer in the floor of the mining coal seam that can realize the in-situ protection of the floor pressure water is obtained , that is, the amount of water resources lost after mining and the amount of water resources lost due to permitted coal mining.

[0052] In the formula, is the advancement distance length of the working face, in m; is the total detection time, in days; is the water pressure of the confined aquifer, in MPa; is the critical equivalent permeability coefficient of the impermeable rock layer at the bottom of the mining coal seam, the unit is D, i.e. Darcy; is the water pressure on the working surface, in MPa.

[0053] Calculation of critical equivalent permeability coefficient of water-repellent rock layer in mining coal seam floor When the amount of water lost from coal mining is allowed to Averaged over every day of the year. The pressurized water flowing to the working face is free water, and the water pressure at the working face is The value is 0 MPa.

[0054] Step S6, determining the feasibility of water-preserving mining by in-situ protection of bottom plate pressure water.

[0055] Step S61: The equivalent permeability of the layered heterogeneous base plate obtained in step S2 is and the critical equivalent permeability coefficient of the impermeable rock layer of the mining coal seam floor obtained in step S5 For comparison, if > , then after coal seam mining, it is impossible to achieve in-situ protection of floor pressure water; if ≤ , then after coal seam mining, whether the in-situ protection of bottom plate pressurized water is achieved should be further judged, and step S62 is executed.

[0056] Step S62: If ≤ , the equivalent permeability of the layered heterogeneous base , Average depth of the broken zone of the mining coal seam floor , Average distance between the bottom of the mining coal seam and the aquifer , working surface length , Advance distance length and water pressure in confined aquifers , substitute into the formula , and obtain the water inflow per unit time within the total time range To ensure safe mining at the working face, if there is no ≥ If the continuous time is more than 5 days, the bottom plate pressure water in-situ protection can be achieved; if there is ≥ If the continuous time is more than 5 days, the in-situ protection of the bottom slab pressurized water cannot be achieved.

[0057] In the formula, is the water inflow per unit time, in m 3 / sky; The amount of water inflow required to ensure safe mining at the working face, in m 3 / day. As a preferred embodiment, The value is 1000m 3 / sky.

[0058] Embodiment 1

[0059] This embodiment takes a working face of a mine in Shanxi, my country, which is threatened by a confined aquifer, as an example. After the bottom plate is reinforced by grouting, the water inflow of the bottom plate is significantly reduced, aiming to determine whether the bottom plate confined aquifer has been protected in situ.

[0060] Step S1: Check the geological and hydrogeological exploration report and the mine development plan of the mine owner to determine the average distance between the bottom of the mining coal seam and the aquifer. , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance , as shown in Table 1.

[0061] Table 1 Aquifer related parameters and working surface parameters

[0062]

[0063] Step S2: Arrange 10×5 drilling points within the mining range consisting of a working face length of 100m and a advancing distance of 600m. Figure 2 As shown in the figure, the distances between the strike and dip measuring points of the working face are 66m and 25m respectively. The average depth of the broken zone of the mining coal seam floor is determined by the traditional segmented water pressure test. The average thickness of the rock layers below the floor crushing zone after mining is 20 m. and the average permeability of each rock layer below the fracture zone See Table 2.

[0064] Table 2 The bottom rock layer below the broken zone

[0065] Serial number Average thickness of rock layer (m) Average permeability of rock formation (D) Cumulative thickness (m) 1 10 <![CDATA[1.50x10 -9 ]]> 10 2 20 <![CDATA[2.00x10 -9 ]]> 30 3 20 <![CDATA[3.00x10 -9 ]]> 50 4 20 <![CDATA[1.00x10 -9 ]]> 70 5 10 <![CDATA[5.00x10 -9 ]]> 80

[0066] The average thickness of each rock layer below the broken zone in Table 2 and the average permeability of each rock layer below the fracture zone , substitute into the formula , calculate the equivalent permeability of the layered heterogeneous base 1.76x10 -9 D.

[0067] Step S3: Test the water pressure of the confined aquifer within one year according to the hydrological long observation hole. Figure 3 As shown in the figure, the average water pressure of the confined water in spring and autumn is 4.45 and 5.56 MPa respectively, and the maximum value is taken as the target water pressure , which is 5.56 MPa. Statistics show that the water pressure exceeds the target in summer and winter Water pressure in confined aquifers and time .

[0068] Step S4: exceed the target water pressure Water pressure in confined aquifers and time , substitute into the formula , calculate the amount of water resources allowed to be lost during coal mining 293266.3m 3 .

[0069] Step S5: The water pressure of the confined aquifer obtained in step S3 , the amount of water resources allowed to be lost during coal mining determined in step S4 , and combined with the working surface water pressure determined by on-site tests , substitute , calculate the critical equivalent permeability of the impermeable rock layer in the floor of the mining coal seam that can achieve in-situ protection of the floor pressure water 2.77x10 -9 D.

[0070] Step S6: The equivalent permeability of the layered heterogeneous base plate obtained in step S2 is and the critical equivalent permeability coefficient of the impermeable rock layer of the mining coal seam floor obtained in step S5 For comparison, ≤ , then after coal seam mining, it should be further determined whether the in-situ protection of bottom plate pressurized water can be achieved.

[0071] The water pressure of the confined aquifer obtained in step S3 , substitute into the formula , which can be simplified to , calculate the water inflow per unit time within the total time range ,like Figure 4 As shown, there is no continuous period of more than 5 days ≥1000m 3 / day, this embodiment can achieve in-situ protection of bottom plate pressurized water.

[0072] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A method for distinguishing water conservation and mining for in-situ protection of floor pressure water, characterized in that: The steps include: S1. Determine the average distance between the bottom of the mining coal seam and the aquifer , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance ; S2. Average depth of the broken zone of the bottom plate of the mining coal seam obtained by detection , the average thickness of each rock layer below the fracture zone , Average permeability of each rock layer below the fracture zone and the equivalent permeability of the layered heterogeneous floor ; S3, detection and statistics of the total time is , water pressure in the confined aquifer at different time periods , determine the target water pressure of the target confined aquifer ; The water pressure of the confined aquifer is measured and target water pressure Compare and get the water pressure exceeding the target Water pressure in confined aquifers and water pressure in confined aquifers Exceeding target water pressure Time ; S4: Target water pressure obtained according to step S3 With water pressure and time , substitute into the formula , and the amount of water resources lost during coal mining can be obtained ; In the formula, is the hydrodynamic viscosity coefficient, in Pa·s; S5, the water pressure of the confined aquifer obtained in step S3 and the amount of water resources lost during coal mining obtained in step S4 , substitute into the formula , and the critical equivalent permeability coefficient of the impermeable rock layer in the mining coal seam floor is obtained ; In the formula, is the total detection time, in days; is the critical equivalent permeability coefficient of the impermeable rock layer at the bottom of the mining coal seam, the unit is D; is the water pressure on the working surface, in MPa; S6. Determine the feasibility of water conservation mining for in-situ protection of floor pressure water; S61, the equivalent permeability of the layered heterogeneous base plate obtained in step S2 and the critical equivalent permeability coefficient of the impermeable rock layer of the mining coal seam floor obtained in step S5 For comparison, if > , then after coal seam mining, it is impossible to achieve in-situ protection of floor pressure water; if ≤ , then execute step S62; S62, the equivalent permeability of the layered heterogeneous base , Average depth of the broken zone of the mining coal seam floor , Average distance between the bottom of the mining coal seam and the aquifer , working surface length , Advance distance length and water pressure in confined aquifers , substitute into the formula , and obtain the water inflow per unit time within the total time range If it does not exist ≥ If the continuous time is more than 5 days, the bottom plate pressure water in-situ protection can be achieved; if there is ≥ If the continuous time is more than 5 days, the bottom plate pressure water in-situ protection cannot be achieved. The amount of water inflow required to ensure safe mining at the working face, in m 3 / sky.

2. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 1, characterized in that: The step S2 comprises the following steps: S21, length of working surface and the length of the advancing distance Arrange A×B drilling points within the mining range to obtain the depth of several bottom plate fracture zones, the thickness of each rock layer below the fracture zone, and the permeability; S22, averaging the depths of several floor crushing zones, the thicknesses of various rock layers, and the permeability detected in step S21 to obtain the average depth of the floor crushing zone of the mining coal seam , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone ; S23, the average depth of the broken zone of the mining coal seam floor obtained in step S22 , the average thickness of each rock layer below the fracture zone and the average permeability of each rock layer below the fracture zone , substitute into the formula , the equivalent permeability of the layered heterogeneous base is obtained ; In the formula, , The number of rock layers below the fracture zone.

3. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 2, characterized in that: In step S1, the average distance between the bottom plate of the mining coal seam and the aquifer is obtained by drilling on site and consulting the geological and hydrogeological exploration report of the mine owner and the mine development plan. , average thickness of aquifer , average penetration Length of working surface and the length of the advancing distance .

4. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 2, characterized in that: In step S2, the depth detection of the bottom plate broken zone is mainly based on on-site water pressure test, supplemented by parallel electrical method. The thickness of each rock layer below the broken zone is obtained by on-site drilling, and the average thickness of each rock layer below several broken zones is obtained by averaging the thickness of each rock layer below the broken zone. , the average permeability of each rock layer below the fracture zone The average value is obtained by testing the water pressure during drilling.

5. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 2, characterized in that: In step S21 A and B The values ​​of are 10 and 5 respectively, and the distances between the strike and dip measuring points of the working face are , .

6. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 2, characterized in that: The total time of detection in step S3 One year is a cycle, and different time periods are divided into four quarters.

7. The method for distinguishing water-retaining mining for in-situ protection of floor pressure water according to claim 6, characterized in that: The target water pressure in step S3 The determination method is: solve the average water pressure of the confined water in spring and autumn, and take the maximum value as the target water pressure .

8. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 7, characterized in that: In step S4, the water pressure exceeding the target water pressure in the confined aquifer state in summer and winter is counted. Water pressure in confined aquifers and time .

9. The method for distinguishing water-retaining mining for in-situ protection of floor pressure water according to claim 6, characterized in that: In step S5, the critical equivalent permeability coefficient of the impermeable rock layer at the bottom of the mining coal seam is calculated. When the amount of water lost from coal mining is allowed to Averaged over every day of the year; water pressure at the working surface The value is obtained through field testing.

10. The method for distinguishing water conservation and mining for in-situ protection of floor pressure water according to claim 2, characterized in that: In step S62 The value is 1000 m 3 / sky.

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