Mine drainage method based on water-saving coefficient method

Abstract

The invention discloses a mine drainage method based on a water-saving coefficient method, which comprises the following steps of: establishing an underground water numerical model according to related data of a coal mine, and identifying and verifying the underground water numerical model; determining the distribution of drill holes and constraint points by combining the water yield property of the aquifer and the influence radius of the hydrophobic drill holes; simulating a drawdown caused by a natural condition under a no-pumping condition, and calculating a safe water level drawdown sj in combination with the initial water level; solving parameters; establishing a mine drainage and drainage model based on a water-saving coefficient method according to actual conditions; and operating the mine drainage model to obtain a drainage scheme. The water-saving coefficient method provided by the invention is simple, convenient and flexible, and any node in the numerical model can also be selected as a constraint condition; compared with a response matrix method, the drainage scheme given by the water-saving coefficient method is more scientific and reasonable, the drainage amount and the drainage time are remarkably reduced, reference is provided for water resource saving and ecological protection, and the method has certain significance in research of water-preserved coal mining and development of an underground water management model.

Description

Technical Field

[0001] The invention relates to a mine drainage method based on a water-saving coefficient method, and belongs to the technical field of mine drainage. Background Art

[0002] my country's coal and water resources are distributed very unevenly. Western China is rich in coal but lacks water resources and faces fragile ecosystems. Jurassic coal mining in western China is widely affected by roof water inundation, and the primary flood control measure is drainage of major aquifers. However, how to scientifically and rationally implement drainage in ecologically fragile areas of western my country remains a challenge.

[0003] To address the challenge of premature mine drainage, management theory based on operations research was introduced to the field of groundwater management in the late 1970s. Two methods for coupling management models with numerical simulations are available: the embedding method and the response matrix method. The embedding method embeds the linear algebraic equations formed by the numerical model simulating groundwater movement as constraints into the management model. When the numerical model is complex or has many nodes, the management model struggles to calculate the optimal result, so this method has not been widely used for mine groundwater drainage. The response matrix method allows arbitrary nodes in the numerical model to be selected as constraints, making it simpler and more flexible than the embedding method. However, it cannot optimize drainage duration. Both the embedding method and the response matrix method have shortcomings.

[0004] A mine water drainage management model based on the response matrix method is constructed. The model's core component is a goal programming algorithm. The flowchart uses a genetic algorithm as an example. Each individual in the population represents a set of decision variables Q(i, k), representing the drainage borehole flow rate. The objective function is to minimize the amount of water discharged. After multiple iterations, the optimal solution is obtained: a set of decision variables that minimizes the amount of water discharged. The iterative process requires generating multiple individuals that satisfy water level constraints. The challenge is how to quickly calculate the water level drawdown for each individual. The response matrix method can address this issue. The key idea behind the response matrix method is to apply the superposition principle to simplify the multi-hole pumping problem into the superposition of multiple single-hole pumping problems. The water level drawdown in the confined aquifer is the sum of the boundary conditions and the water level drawdown caused by drainage borehole pumping. The drawdown caused solely by pumping follows the superposition principle for linear systems. Dividing the drainage time into several equal management stages can reduce the amount of water discharged. The drawdown caused by a single pumping well is represented by the unit impulse response function β(i, j, k), where β represents the drainage borehole, β represents the constraint point, and β represents the management stage. The drawdown due to pumping alone can be expressed as The unit impulse response function can be solved through groundwater numerical simulation. The existing technology does not point out the regular characteristics between drainage time and drainage volume, and it is impossible to optimize the drainage time.

[0005] At present, most drainage work is extensive and lacks scientific and reasonable planning, which is specifically manifested in the large number of drilling holes on the working face, too long drainage time, and too large drainage volume. The mine drainage management model can reasonably allocate the flow rate of the drainage drilling holes and reduce the waste of water resources. At present, the mine drainage management model is mainly constructed through the response matrix method. This method can optimize the flow rate of the drainage drilling holes with the purpose of minimizing the drainage volume and realize water-saving coal mining. However, the response matrix method does not point out the regular characteristics between the drainage time and the drainage volume, and cannot optimize the drainage time. In response to this problem, the present invention proposes a mine drainage method based on the water-saving coefficient method. Summary of the Invention

[0006] The present invention aims to provide a mine drainage method based on the water-saving coefficient method and proposes a new groundwater advance drainage management model with shorter drainage time and smaller drainage volume.

[0007] The present invention proposes a mine drainage model based on the water-saving coefficient method, which is a new method for coupling management models with numerical simulations. The water-saving coefficient refers to the ratio of the depth drawdown at a certain point within a period of time to the amount of water discharged from the drainage borehole under the condition of single-hole constant flow pumping, and is used to evaluate the water-saving effect of the drainage work. According to the Theis formula, under the condition of single-hole constant flow pumping, the size of the water-saving coefficient has nothing to do with the flow of the drainage borehole, but is only related to time; as time goes on, the water-saving coefficient first increases and then decreases. Based on this principle, combined with the target planning method, the groundwater advance drainage management model proposed in the present invention significantly reduces the drainage amount and drainage time compared with the existing technology.

[0008] The present invention provides a mine drainage method based on a water-saving coefficient method, comprising the following steps:

[0009] Step 1: Based on relevant data of coal mines, establish a groundwater numerical model and identify and verify it.

[0010] Specifically, a groundwater numerical model was developed based on relevant coal mine data, including the aquifer top and floor elevations, permeability coefficient, and initial water level. A pumping test process was simulated, and the simulated results were compared with the actual results. If the results were similar, the groundwater numerical model was able to simulate the actual groundwater flow field.

[0011] Step 2: Determine the distribution of boreholes and constraint points based on the water richness of the aquifer and the influence radius of the hydrophobic borehole.

[0012] Specifically, the locations of constraint points and drainage holes must be determined to ensure that the drainage holes' influence covers the entire working surface. In areas with high water content, the number of drainage holes can be increased. Drainage holes and constraint points cannot be placed at the same node. If they are, calculation results show that drainage time is very short, and the influence range cannot cover the entire working surface.

[0013] Step 3: Simulate the drawdown caused by natural conditions without pumping, and calculate the safe water level drawdown s based on the initial water level j .

[0014] Specifically, calculate the safe water level s j :Without setting up pumping wells, simulate the groundwater flow field under natural conditions, calculate the water level at each constraint point, and the difference between the calculated result and the safe water level is s j .

[0015] Step 4: Solve for the parameter (4πT) ij ,

[0016] Step 5: Based on the actual situation, establish a mine drainage model based on the water-saving coefficient method.

[0017] Specifically, the drainage capacity of a single hole is determined by the drilling equipment, and the drainage capacity of a mine is determined by the mine drainage system.

[0018] Step 6: Run the mine drainage model to obtain a drainage plan.

[0019] Specifically, the algorithm is run to obtain a drainage plan; if the calculation results are different each time, the algorithm is run multiple times to obtain the result with the smallest total drainage volume.

[0020] The mine drainage method provided by the present invention is specifically described as follows:

[0021] The basic idea behind the water-saving coefficient method is to first explore the pumping scheme that minimizes the amount of water released, given a single pumping hole with a constant flow rate. Secondly, the case of a single pumping hole and a single constraint point is expanded to include multiple pumping holes and multiple constraint points. Finally, goal programming is used to develop a pumping scheme for each pumping hole.

[0022] The water-saving coefficient is used to evaluate the water-saving effect of drainage work. It refers to the ratio of the depth drop s caused by a drainage borehole at a certain point to the volume V (drainage volume) of the pumped water. When a single hole is pumping water at a constant flow rate, the water-saving coefficient at a certain point over a period of time is expressed as the average water-saving coefficient, which is recorded as It can be expressed as:

[0023]

[0024] Where: is the average water saving coefficient, m -2 ; s is the drawdown at a certain point, m; V is the drainage volume of the hydrophobic borehole, m 3 ; Q is the flow rate of the hydrophobic drilling, m 3 / d; t is the pumping time, d.

[0025] When pumping water at a constant flow rate from a single hole, the water-saving coefficient at a certain point in a very short period of time starting from a certain moment is expressed as the instantaneous water-saving coefficient, recorded as J, which can be expressed as:

[0026]

[0027] According to Theis formula:

[0028]

[0029] Where: s is the drawdown, m; Q is the flow rate of the drainage borehole, m 3 / d; T is the hydraulic conductivity, m 2 / d; t is the pumping time, d; r is the horizontal distance from the calculation point to the drainage borehole, m; S is the water storage coefficient of the aquifer, dimensionless; W represents the well function. The partial derivative of the Theis formula with respect to time t is

[0030]

[0031] Dividing both sides of the equation by Q yields

[0032]

[0033] It can be seen that the instantaneous water saving coefficient is a function of time t ( Figure 2 ), which has nothing to do with the flow rate of the hydrophobic borehole. As time t increases, J first increases and then decreases. In addition, the area of the shaded rectangle is equal to the area enclosed by the curve, and the height of the rectangle is Can reflect the water-saving effect, J is to help judge As time t increases, if Increase; if Decrease; if maximum.

[0034] If the parameters 4πT and Known, solve the equation Right now The solution is The time of maximum is denoted as t * . The drawdown corresponding to the safety water level of the constraint point and t * Substituting into the Theis formula, we can get Q * . Hydrophobic drilling with flow rate Q * Carry out constant flow pumping, at t * The safe water level is met and the amount of water discharged is minimal.

[0035] It can be concluded that:

[0036] 1) When pumping water at a fixed flow rate from a single hole, the water-saving coefficient is related to the pumping time and has nothing to do with the flow rate of the drainage borehole. The pumping time is t * The water-saving effect is best.

[0037] 2) Hydrophobic drilling with flow rate Q * Carry out constant flow pumping, at t * The safe water level is met and the amount of water discharged is minimal.

[0038] 3) Pumping water by changing the flow rate is not the most water-saving pumping method.

[0039] Beneficial effects of the present invention:

[0040] (1) The water-saving coefficient method is simple and flexible, and any node in the numerical model can be selected as a constraint condition;

[0041] (2) Compared with the response matrix method, the drainage scheme given by the water-saving coefficient method of the present invention is more scientific and reasonable, and the drainage amount and drainage time are significantly reduced, which provides a reference for saving water resources and ecological protection, and has certain significance for the research on water-saving coal mining and the development of groundwater management models. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart showing the mine drainage model based on the response matrix method;

[0043] Figure 2 Indicates the instantaneous water-saving coefficient change curve;

[0044] Figure 3 A flow chart showing a mine drainage model based on the water conservation coefficient method;

[0045] Figure 4 It represents the results of groundwater numerical model identification and verification;

[0046] Figure 5 represents the distribution of hydrophobic drilling holes;

[0047] Figure 6 Represents parameter t * Calculation results. DETAILED DESCRIPTION

[0048] The present invention is further illustrated below by way of examples, but is not limited to the following examples.

[0049] Example 1:

[0050] The present invention provides a mine drainage method based on the water saving coefficient method. The specific implementation method is as follows, and the flow chart is shown in FIG. Figure 3 .

[0051] Step 1: Based on relevant data of coal mines, establish a groundwater numerical model and identify and verify it.

[0052] Step 2: Determine the distribution of boreholes and constraint points based on the water richness of the aquifer and the influence radius of the hydrophobic borehole.

[0053] Step 3: Simulate the drawdown caused by natural conditions without pumping, and calculate the safe water level drawdown s based on the initial water level j .

[0054] Step 4: Solve for the parameter (4πT) ij ,

[0055] Step 5: Based on the actual situation, establish a mine drainage model based on the water-saving coefficient method.

[0056] Step 6: Run the mine drainage model to obtain a drainage plan.

[0057] The above drainage method is described in detail as follows:

[0058] 1. Overview of the study area of this example: Hongliulin Coal Mine is located in Shenmu City, Shaanxi Province, China. The overall terrain is high in the northwest and low in the southeast, with a ground elevation of approximately +1200 to +1270m, and a relative height difference of 100 to 150m. -2 The coal seam is located at the top of the fourth section of the Yan'an Formation and is denuded in the eastern part of the mining area. -2 The aquifer and aquiclude overlying the coal seam are: 2 -2 The coal seam is overlain by normal bedrock fissure confined water aquifer, weathered bedrock aquifer, laterite relative aquifer and Quaternary aquifer. -2 Coal seam, working face area water-conducting fracture zone is all connected to the surface. The Quaternary pore water-bearing aquifer (loose sand layer) in the mining area is mostly water-free, and there is no water in the E52201 working face area. -2 The normal bedrock fracture confined water aquifer overlying the coal seam has weak water richness and can be regarded as an aquiclude. -2 The main water-filled aquifer overlying the coal seam is the weathered bedrock aquifer.

[0059] 2. The groundwater numerical simulation process is as follows:

[0060] Based on the structural characteristics of the weathered bedrock aquifer, it has no hydraulic connection with other aquifers. The recharge and discharge of the weathered bedrock aquifer are lateral. Through a comprehensive analysis of the weathered bedrock aquifer structure, boundary conditions, and source and sink terms, its mathematical model is a three-dimensional heterogeneous, unsteady flow:

[0061]

[0062] Where: K is the permeability coefficient, m / d;

[0063] W is the source and sink term of natural conditions, d -1 ;

[0064] Q is the source and sink term of human conditions, d -1 ;

[0065] μ s is the elastic water storage rate, m -1 ;

[0066] t is time, d;

[0067] Ω is the simulation area;

[0068] H0 is the initial water head, m;

[0069] H is the water level elevation, m;

[0070] s1 is the first type of head boundary.

[0071] The simulation was performed using Visual MOFLOW software. The simulation range is the western 2 -2 In the coal seam occurrence area, the simulation time is 1 year, divided into 4 equal time steps. The model identification verification results are as follows Figure 4 .

[0072] 3. Based on the evaluation of water-richness in the mining area, the development of water-conducting fracture zones and the analysis of water inrush hazards, the distribution of drainage boreholes and restraint points in the E52201 working face area is as follows: Figure 5 Drainage holes and restraint points are staggered. Specifically, based on water-richness assessment, the development of water-conducting fracture zones, and the risk of water inrush, drainage holes and restraint points are densely distributed in areas with high water content or prone to water inrush. These three parameters rarely vary within the working face, so a uniform distribution is sufficient.

[0073] In the existing research on the response matrix method, there is a configuration method that places the constraint monitoring points and the drainage boreholes at the same location; that is, according to the current operation of the response matrix method, these 26 points are both drainage boreholes and constraint points. However, when using the water-saving coefficient method, this spatial overlapping setting method will cause the water-saving coefficient method to exhibit abnormal optimization characteristics: the drainage time is too short, and the depth reduction funnel formed by drainage fails to effectively extend to the entire working face. At this time, the water level drop at each constraint point is only due to the local effect of the corresponding borehole, and fails to reflect the overall evolution law of the seepage field. It should be pointed out in particular that the goal of setting up constraint nodes is to achieve overall water level control in the mining area, and the "one hole, two uses" model with overlapping positions is fundamentally inconsistent with this control logic. In the application of the water-saving coefficient method, the principle of spatial separation of constraint points and drainage boreholes must be maintained to avoid model distortion caused by node overlap. Therefore, in the water-saving coefficient method, drainage boreholes and constraint points cannot be set at the same location, so the two are staggered; such as Figure 5 As shown, there are two rows of holes, each row has 13 holes, which are arranged at equal intervals, and the hydrophobic drilling holes and the restraint points are arranged alternately.

[0074] The groundwater numerical model was used to pump water from 13 drainage boreholes one by one, and water was pumped only in the first stage with a flow rate of 10m 3 / d, record the drawdown in four stages, and organize the data to obtain the unit impulse response matrix of the four stages; pump water from 13 drainage boreholes one by one, continuously pump water for one year, with a flow rate of 10m 3 / d, using the first and fourth stage drawdown solution parameters (4πT) ij 、 and Visual MODFLOW can calculate the depth drop at different times, that is, solve the parameters "depth drop s1, s2 at different times t1, t2", and then calculate the parameters. Set 10m 3 A flow rate of / d can make the unit impulse response matrix more accurate.

[0075] 4. Comparative experiment: Establishing a mine drainage model based on the response matrix method:

[0076] Considering the actual drainage situation of weathered bedrock aquifers, the flow rate of a single hole shall not exceed 2000m 3 / d, according to the mine drainage system, the mine drainage capacity is 37920m 3 / d. If the management stages are not divided, the mathematical model of the mine groundwater drainage management model is expressed as follows:

[0077]

[0078] Where: Q i is the flow rate of the ith drainage borehole; β(i,j) is the unit impulse response function, which represents the drawdown caused by the i-th drainage borehole unit pumping at the constraint point j at the end of the management time; s j Lower the water level to a safe level.

[0079] The solution is solved using a genetic algorithm, and the results are shown in Table 1. This solution indicates that each drainage borehole will continue to pump water at a given flow rate for one year. The total drainage volume is 100123.468m 3 .

[0080] The management time of one year is divided into four stages, each stage has equal duration. The mathematical model of the mine groundwater drainage management model is expressed as follows:

[0081]

[0082] where Q(i,k) is the flow rate of the i-th drainage borehole in the k-th stage; β(i,j,k) is the unit impulse response function, which represents the drawdown caused by the unit pumping of the i-th drainage borehole at the constraint point j at the end of the k-th stage.

[0083] The solution is solved using a genetic algorithm, and the results are shown in Table 2. This solution indicates that each drainage borehole continues to pump water at a constant flow rate according to the given flow rate at each stage. The total drainage volume is 74988.589m 3 .

[0084] 5. The mine drainage model based on the water-saving coefficient method is established as follows:

[0085] The mathematical model of mine groundwater drainage management model is expressed as follows:

[0086]

[0087] Solve for the above parameters:

[0088] The first step of the mine groundwater advance drainage management model based on the water saving coefficient method is to adjust the parameters 4πT and Solution. Using the groundwater numerical simulation method, we can calculate the drawdown at different times under the condition of constant flow rate pumping from a single hole. The drawdown at different times t1 and t2 are recorded as s1 and s2; let k = t2 / t1, l = s2 / s1. Theis formula shows that the change in drawdown s is due to the change in the well function.

[0089] Where u>0, k>0, k≠1. Use the bisection method to find the zero point u of the function f(u). After finding u, we can find the parameters 4πT, and t * The function f(u) is obviously continuous, and the monotonicity is proved as follows:

[0090] Taking the derivative of f(u) we get:

[0091]

[0092] Arranged:

[0093]

[0094] The variables are replaced:

[0095]

[0096]

[0097] When k < 1, Then f'(u)>0

[0098] When k>1, Then f'(u)<0

[0099] Therefore, when k>0, k≠1, f(u) is monotonic.

[0100] After completing the parameter solution, the goal programming method is used to obtain the final hydrophobic solution.

[0101] Build the model based on the above:

[0102] Combined with the target programming method, a mine drainage management model based on the water saving coefficient method is constructed ( Figure 3 ), the management model consists of three parts: decision variables, objective function and constraints. i and pumping time t i As the decision variable. Theis formula and superposition principle are used to calculate the drawdown and construct the water level constraint. The number of drainage boreholes is m, the number of constraint points is n, and one drainage borehole corresponds to one constraint point. Therefore, the number of each parameter is m×n, which is recorded as (4πT) ij , i represents a hydrophobic drilling hole, and j represents a constraint point.

[0103] The structure of the mine groundwater advance drainage management model is as follows:

[0104] Objective function:

[0105] Water level constraint:

[0106]

[0107] Time constraints:

[0108] Other constraints:

[0109]

[0110] 0 i <Q'

[0111] where Q h is the mine drainage capacity, and Q′ is the maximum drainage capacity of a single hole.

[0112] After the parameters are determined, the goal programming method is used to solve Q i and t i .Q i and t i The purpose of the present invention is to provide a drainage scheme, which includes the number, position, flow rate and drainage time of the drainage holes.

[0113] ​The solution was solved using a genetic algorithm, and the results are shown in Table 3. This solution means that each drainage borehole continuously pumps water at a fixed flow rate according to the given flow rate and time, and each drainage borehole ends the drainage work at the same time instead of starting the drainage work at the same time. The total drainage volume is 45022.254m 3 .

[0114] Table 1. Response matrix method hydrophobic scheme without dividing management stages

[0115]

[0116] Table 2. Response matrix method hydrophobic scheme divided into four management stages

[0117]

[0118] Table 3. Mine drainage scheme based on water saving coefficient method

[0119]

[0120] 6. Result analysis:

[0121] Three mine drainage management models were used to advance drainage of roof water in the E52201 working face of Hongliulin Coal Mine. The three models were the response matrix method without dividing the management stage, the response matrix method with dividing the management stage, and the water saving coefficient method. The results showed that the drainage volume calculated by the response matrix method without dividing the management stage was 100123.468m 3 , which took 1 year, as shown in Table 1; the drainage volume calculated by the response matrix method of the divided management stage is 52924.823m 3 , which took 91.25 days, as shown in Table 2; the drainage volume calculated by the water-saving coefficient method is 45022.254m 3 , which took 58.43 days, as shown in Table 3. The drainage scheme given by the water-saving coefficient method is more scientific and reasonable, and the drainage amount and drainage time are significantly reduced.

[0122] Compared with the non-divided management stage, the response matrix method with divided stages has a smaller drainage volume, which shows that too long pumping time will lead to an increase in drainage volume, and the short-time and high-flow pumping method has a better water-saving effect. Visualization results can be seen in Figure 6 It can be seen that for the same hydrophobic borehole, the farther the distance between the constraint points is, the corresponding t * For a constraint point, the drawdown is mainly caused by the hydrophobic drilling near the constraint point, corresponding to Figure 6 The values near the diagonal are basically less than 90d. Therefore, the drainage drilling flow rate in the first three stages of the response matrix method is 0, and there is still room for optimization of the drainage volume.

[0123] The water-saving coefficient method can optimize the drainage time, and the drainage scheme given is more scientific and reasonable, with significantly reduced drainage volume and drainage time. However, the mathematical model of the water-saving coefficient method is more complex, and there is a risk of falling into a local optimal solution when solving it using a genetic algorithm. It is recommended to optimize the algorithm to expand the search efficiency of the solution space.

[0124] The experimental data was verified and the response matrix method was used to repeatedly run the model. The calculation results were the same each time. The results of the water-saving coefficient method were quite different. Therefore, the calculation results of this time are not necessarily the optimal solution. The algorithm was repeatedly run and the calculation results were different each time. The final result is: 45022.254m 3 The amount of water released is relatively small.

[0125] The following conclusions were drawn from the above examples: 1) The magnitude of the water-saving coefficient is independent of the flow rate of the drainage borehole, but is related to time. With increasing time, the water-saving coefficient first increases and then decreases. The water-saving coefficient is maximum when it is equal to the instantaneous water-saving coefficient. 2) In the response matrix method, the amount of drainage can be effectively reduced by discretizing the management cycle into multiple time periods. 3) The water-saving coefficient method has significant advantages over the response matrix method. This method can achieve dual optimization of water level safety control and water resource consumption. Compared with the response matrix method, it is more scientific and reasonable, significantly reducing the drainage volume and drainage time. 4) In the water-saving coefficient method, a certain distance should be maintained between the constraint point and the drainage borehole to avoid model distortion caused by node overlap.

Claims

1. A mine drainage method based on the water-saving coefficient method, characterized in that The following steps are involved: Step 1: Based on relevant data of coal mines, establish a groundwater numerical model and identify and verify it; Step 2: Determine the distribution of boreholes and constraint points based on the water-richness of the aquifer and the influence radius of the hydrophobic boreholes; Step 3: Simulate the drawdown caused by natural conditions without pumping, and calculate the safe water level drawdown s based on the initial water level j ; Step 4: Solve for the parameter (4πT) ij , Step 5: Based on the actual situation, establish a mine drainage model based on the water-saving coefficient method; Step 6: Run the mine drainage model to obtain a drainage plan.

2. The mine drainage method based on the water-saving coefficient method according to claim 1 is characterized in that: The specific content of step one is: based on relevant data of the coal mine, including the elevation of the top and bottom of the aquifer, the permeability coefficient, the initial water level, etc., a groundwater numerical model is established; the pumping test process is simulated, and the simulation results are compared with the actual results. If the results are not much different, it means that the groundwater numerical model can simulate the real groundwater flow field.

3. The mine drainage method based on the water-saving coefficient method according to claim 1 is characterized in that: The specific content of step two is: determine the location of the constraint point and the hydrophobic drilling hole, ensure that the influence range of the hydrophobic drilling hole covers the entire working surface, and increase the number of hydrophobic drilling holes in areas with strong water-richness; the hydrophobic drilling hole and the constraint point cannot be set at the same node. If set at the same node, the calculation results show that the hydrophobic time is very short and the influence range cannot cover the entire working surface.

4. The mine drainage method based on the water-saving coefficient method according to claim 1 is characterized in that: The specific content of step three is: Calculate the safe water level: do not set up a pumping well, simulate the groundwater flow field under natural conditions, calculate the water level at each constraint point, and the difference between the calculated result and the safe water level is s j .

5. The mine drainage method based on the water-saving coefficient method according to claim 1 is characterized in that: Step 5: The specific contents of establishing a mine drainage model based on the water-saving coefficient method are as follows: The flow rate Q of each drain hole i and pumping time t i as decision variables; Theis formula and superposition principle are used to calculate the drawdown and construct the water level constraint. The number of drainage boreholes is m, and the number of constraint points is n. One drainage borehole corresponds to one constraint point, so the number of each parameter is m×n, which is recorded as (4πT) ij , i represents the hydrophobic drilling hole, and j represents the constraint point; The structure of the mine groundwater advance drainage management model is as follows: Objective function: Water level constraint: Time constraints: Other constraints: Where Q0 is the mine drainage capacity, Q′ is the maximum drainage capacity of a single hole; After the parameters are determined, the goal programming method is used to solve Q i and t i ;Q i and t i Indicates the flow rate and drainage time of the drainage drilling hole.

6. The mine drainage method based on the water-saving coefficient method according to claim 1 is characterized in that: The specific content of step six is: run the algorithm to obtain a drainage plan; if the calculation results are different each time, run the algorithm multiple times and take the result with the smallest total drainage volume.

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