Disclosure of Invention
The invention aims to provide a multi-objective optimization method for low-permeability aquifer group hole dredging and descending, which aims at the high-pressure-bearing water dredging and descending engineering of a coal seam bottom plate, and is used for constructing the least water drainage hole under the condition of meeting the safety production, and the single-hole flow is the least to achieve the optimal dredging and descending effect, meanwhile, the total water drainage amount and the drilling engineering amount are reduced to the greatest extent, so that the optimal balance among safety, economy and environmental benefits is realized, the construction cost is reduced, and the aim of safe exploitation is fulfilled; aiming at the underground sparse drill hole position, selecting the drill hole position in the roadway, summarizing the roadway where the drill hole candidate position is located into a straight line section, searching the best point position meeting the condition on the straight line section, and obtaining accurate hole position coordinates. Because the water-bearing layer to be dredged and lowered simultaneously meets the constraint conditions that the single-hole flow is minimum to achieve the optimal dredging and lowering effect and the number of holes is minimum, the method adopts a multi-target particle swarm optimization (MOPSO) algorithm, has higher searching speed and efficiency, is simpler, and can quickly obtain the optimal solution of the model; because the deep mining limestone aquifer has the characteristics of large water pressure, poor permeability and nonuniform water enrichment, the single-hole water drainage is generally difficult to meet the requirement, and the aim of dredging and lowering is achieved and meanwhile the mining cost of the coal mine and the damage degree to the ecological environment are effectively reduced by optimizing the drilling quantity and the drilling flow in the group-hole water drainage.
The aim of the invention can be achieved by the following technical scheme:
the multi-objective optimization method for low-permeability aquifer group hole thinning comprises the following steps:
s1: and determining the water level control of the dewatering area according to the mining engineering layout.
S2: and collecting geological and hydrogeological data of a research area, determining the permeability of the aquifer to be dredged, determining the safe water level and the descending depth of a control point and other parameters, and calculating the maximum descending depth of a water drain hole, namely, when the water level of the water drain hole is reduced to the top plate of the aquifer, and recording as Smax.
S3: and constructing a drainage drilling candidate position.
S4: and setting the degree of water holes penetrating through the aquifer, setting constraint conditions of the number n of holes, the single-hole flow Q and the descending depth S of the water level control point, and definitely taking the minimum of Q and n as an optimization function to establish an optimization model.
S5: and (5) solving the optimal Q, n value of the model by using a multi-objective optimization method.
S6: the optimization model is discussed and production practices are directed.
Preferably, in the step S1, a water level control point of the dewatering area is determined according to the mining engineering layout, in the actual water drainage engineering, a boundary covering the mining working face is used as a dewatering boundary, and a working face end point is selected as the water level control point in the dewatering boundary.
Preferably, in the step S2, geological and hydrogeological data of the research area are collected, the permeability of the aquifer to be dredged is definitely determined, parameters such as the safe water level and the descending depth of the control point are determined, and the maximum descending depth Smax of the water drain hole is calculated.
The water is discharged at a certain flow rate through the aquifer, the pressure-bearing water head is reduced, and the pressure-bearing water head is reduced to below a safety water head, so that the aim of safe exploitation is fulfilled, the safety water head value is a key index of sparse-drop switching, the safety water head value is the water head pressure born by a water-resisting layer of a coal seam bottom plate, the smaller the safety water head value is, the larger the water head to be reduced is, if the safety water head value is larger than an actual water head value, the direct pressure exploitation can be carried out without water discharge, and the safety water head of a working face is generally determined by adopting a water burst system method in actual engineering, as shown in a formula (1).
p=TsM (1)
Wherein M is the thickness of a water-resisting layer, the unit M and Ts are critical water bursting coefficients, 0.06MPa/M is taken at a section with structural damage according to the water control requirement of a coal mine, and 0.1MPa/M is taken at a complete section without fracture.
In the actual water discharging project, the boundary of the coverage mining working face is used as a dredging and descending boundary, and the end point of the working face is selected as a water level control point in the dredging and descending boundary to calculate the safe water level. And determining the elevation Hd of the water-proof bottom plate of the coal seam (namely the elevation of the top plate of the water-bearing layer) and the initial elevation H0 of the water level control points, converting the safe water pressure into the safe water level by using a formula Hs=p×100+Hd, and obtaining the safe water level drop depth at the water level control points by using a formula Ss=H0-Hs.
Preferably, in the step S3, a drainage drilling candidate position is constructed: summarizing a drainage roadway needing to be provided with a drainage hole into a straight line segment, wherein the inclination angle is theta, coordinates of two end points A, B of the known drainage roadway are (xp 1, yp 1) and (xp 2, yp 2), obtaining a straight line equation of the roadway through a formula y=ax+b by using any two points x and y on the straight line segment, marking a coordinate range xp1 which is less than or equal to x and less than or equal to xp2 where x point of the straight line segment is positioned, wherein a is a straight line slope, b is a straight line intercept, (xp 1, xp 2) is a straight line segment abscissa range, and the roadway total length is L.
N water drainage drilling holes are distributed in a water drainage roadway and are respectively F1, F2., fi., fn and are arranged at equal intervals, the distance between adjacent holes is D, and the coordinates of any water drainage hole are (xci, yci); m water level control points are arranged in the working surface and are C1, C2 … Cj and Cm respectively, any control point coordinate is (xj and yj), the distance between any water discharging hole and any water level control point is recorded as rij, the water discharging quantity of each water discharging hole is equal, Q is respectively arranged, and the water discharging hole and the water level control point are shown in the figure 1.
Preferably, the constraint conditions of the degree of water drain hole penetration through the aquifer, the number n of holes, the single-hole flow Q and the descending depth S of the water level control point are set in the S4, and Q and n minimum are definitely used as optimization functions to establish an optimization model; the optimization of the limestone aquifer group hole dredging engineering comprises the optimization of flow and water drain hole quantity, aiming at the limestone aquifer with high pressure bearing and low permeability, the single hole flow and the water drain hole quantity are usually used as objective functions in an optimization model, namely, the minimum single hole flow and the water drain hole quantity are achieved under the constraint conditions of water level lowering and the like, the underground water resource is protected to the maximum extent, and the objective functions can be expressed as follows:
Z=opt{Q,n} (2)
when the water is discharged for the incomplete well, the confined aquifer where the incomplete well is arranged meets the assumption condition used when the Theis formula is deduced, and when the linear distance r between the observation point and the water discharge hole is less than or equal to 1.5M, the descending equation is as follows:
wherein:
wherein Q is the water discharge amount of the drilled hole; r is the linear distance between the calculated point and the water discharge borehole; s is the water level lowering depth; k is the permeability coefficient of the aquifer; m is the thickness of the whole aquifer; u is the elastic water release coefficient; w (u) is a Tex complete well function; u is the well function argument; ζ is the non-integrity additional drag coefficient; d is the distance from the top plate of the water-bearing layer to the top of the drain hole filter, l is the distance from the top plate of the water-bearing layer to the bottom of the sparse and descending drilling filter, and z is the distance from the top plate of the water-bearing layer to the bottom of the water level observation hole, namely the opening position; t is the drain time.
From equation (3), it can be seen that the incomplete well drop is made up of two parts, the former representing the corresponding complete well drop and the latter representing the additional drop caused by the curvature of the flowline around the pumping well due to the pumping well imperfections.
When the water drain hole completely penetrates through the thickness of the whole water-bearing layer, namely a complete well is drilled, or the linear distance r between an observation point and the center of the water drain hole is more than 1.5M, the additional resistance coefficient is negligible, the corresponding complete well formula is simplified, and the descent depth equation is converted into:
when the group holes are used for discharging water, the water quantity is respectively Q1, Q2 and … Qn, and the water head drop depth of any point can be calculated according to the seepage superposition principle, namely, the water head drop depth of each single water discharging hole is equal to the sum of the water head drop depths of the single water discharging holes, as shown in the formula.
Let the left lower corner of the tunnel be first water hole (x 1, y 1) lay the position, the water hole can not surpass the water tunnel scope, according to tunnel endpoint coordinate and tunnel straight line equation, the constraint condition of this time crowd hole water hole number n can write as:
when the water level of the water discharging hole is reduced to the top plate of the water-bearing layer (marked as Smax), the water discharging flow of the drilled hole is marked as Qmax, the flow is the maximum constraint condition of the single-hole flow in optimization, namely the upper limit value of the drainage flow of the drilled hole, the radius of the water discharging hole is set as rw, and the flow constraint condition is as follows in consideration of the mutual interference among the water discharging holes: when the water drain hole is a complete well or a non-complete well but the hole spacing D is more than or equal to 1.5M, the i-th water drain hole is provided with:
when the water drain hole is an incomplete well, if the hole distance D is smaller than 1.5M, when the mutual interference of the incomplete additional resistance coefficient ζ is not considered, the water drain hole with the i-th water drain hole is:
the water level drop of all control points should reach the safe exploitation purpose, and for any jth water level control point, the safe water level drop is Ssi, and the constraint conditions are as follows:
when the water drain hole is a complete well or a non-complete well but r is more than 1.5M, the method comprises the following steps:
when the water drain hole is a non-complete well and the linear distance r between the water level control point and the water drain hole is less than 1.5M, the water level control point comprises:
the Q and n minimum optimization model at this time is: min (Q) and min (n)
Preferably, in the step S5, the optimal Q, n value of the model is obtained by using a multi-objective optimization method, and for the problem of hydrophobic property of the high-bearing low-permeability limestone aquifer, because the aquifer water-rich property has the characteristic of strong non-uniformity, the safe mining in the whole working face is generally realized by adopting an encrypted hydrophobic drilling mode, but the mining cost is necessarily increased by constructing too many drilling holes, if the drilling holes are reduced, the single-hole water discharge amount is necessarily increased, but because of the characteristic of low permeability, the single-hole water discharge amount is not too large, otherwise, the hydrophobic effect is poor, the depressurization is not in place, so that the hidden danger of water burst is caused, therefore, the optimization target is to construct the least water discharge hole under the condition of meeting the safety water head of the water level control point, the single-hole flow is minimum to achieve the optimal hydrophobic effect, and meanwhile, the total water discharge amount is expected to be minimum, so that the multi-objective optimization problem is realized.
The invention adopts a multi-objective particle swarm optimization (MOPSO) algorithm to solve, the multi-objective particle swarm algorithm expands the particle swarm algorithm into a multi-objective optimization design, and the calculation flow is shown in figure 2.
Preferably, in the step S5, an optimization model is discussed, production practice is guided, and an optimal scheme (meeting the conditions of reducing single-hole flow, properly encrypting a water drainage hole and the like) is formulated according to the optimization result to solve the problem of thinning and lowering of the heterogeneous low-permeability limestone aquifer in actual engineering.
The invention has the beneficial effects that:
1. aiming at the high-pressure-bearing water dredging engineering of the coal seam floor, the invention starts from the characteristics of low permeability of the aquifer, the requirements of economy, environmental protection and the like, and under the condition of meeting the safety production, the invention constructs the least water drainage hole, and the single-hole flow rate is minimum to achieve the optimal dredging effect, simultaneously reduces the total water drainage amount and the drilling engineering amount to the greatest extent, realizes the optimal balance among safety, economy and environmental benefits, reduces the construction cost and achieves the aim of safe exploitation;
2. the method is characterized in that aiming at the underground sparse drainage drilling position, the drilling position is selected in the roadway, the roadway where the drilling candidate position is located is generalized into a straight line section, and the best point meeting the condition is searched on the straight line section, so that accurate hole position coordinates can be obtained. Because the water-bearing layer to be dredged and lowered is required to meet the constraint condition that the single-hole flow is minimum to achieve the optimal dredging and lowering effect and the number of holes is minimum, the method adopts the multi-target particle swarm algorithm, has higher searching speed and efficiency, is simpler, and can quickly obtain the optimal solution of the model.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Taking a certain mine as an example, the embodiment takes 10 coal beds as main mining, the 10 coal beds are about 35-55m away from the top of a bearing aquifer of the Taiyuan limestone, the 1-4 bearing aquifer which affects the safe mining of the 10 coal and is mainly at the upper section of the bearing aquifer, the mine stratum is towards the north and the south, and is inclined to the east, the dip angle is about 10 degrees, the well field fault is developed in a monoclinic structure, but most of the water is not guided and not contained, and the water-containing rock group at the upper section of the Taiyuan group is a closed and weak water-containing layer due to the water blocking effect of the fault, so that the feasibility is provided for the drainage depressurization exploitation.
In the exploration and production stage, drilling holes such as 22-23-1, 27-1, 07-3 and the like are sequentially arranged in a mine, and a water pumping test is carried out on the ash-containing water layer at the upper section 1-4 of the Tai gray, so that the water-rich parameter results are listed in Table 1.
TABLE 1 Taiyuan group 1-4 limestone water pumping test for mine
The pumping results in Table 1 show that the water-containing layer q=0.0052-0.773L/sm in the upper section 1-4 of the Taiyuan group, K=0.026-3.93 m/d, the shallow hidden outcrop is strong in water enrichment and connectivity, and gradually weakens to be a weakly permeable layer towards the deep. In addition, the difference of K values of different drilling holes q is large, so that the non-uniformity of the water enrichment and permeability of the water-bearing layer at the upper section of the too-gray layer is further illustrated. From the analysis, the mine deep karst fracture aquifer has typical high pressure bearing and low permeability characteristics.
The 1013 and 1011 working surfaces are positioned in a 101 mining area, the mining area is divided into a plurality of block sections by a plurality of large faults of F9, F10 and F11, wherein the 1013 and 1011 working surfaces are positioned between the two faults of F9 and F10, the hydrogeological conditions are relatively independent, the too gray water supply source is limited, and the hydrophobicity is strong. The working face is arranged below a Taiyuan group high-bearing limestone aquifer, wherein the thickness of the 1-4 limestone aquifer is 50m, 126 1-4 limestone water detection drilling holes constructed in a mining area are drilled, and the water outlet is larger than 5m 3 And (3) the number of holes per hour is only 4, most of the holes are dry holes, the water yield is less than 2%, and the characteristics of good water repellency and insufficient supply of the limestone water on the bottom plate are further proved.
Before stoping, the water level elevation of a long observation hole 14-1 hole in the stope is-50 m, the minimum water-resisting layer thickness of the coal bed and the water-bearing layer is 45m, the maximum water pressure born by the bottom of the water-resisting layer is 4.65MPa calculated according to the minimum elevation-515 m of the working face, the water-bursting number is about 0.103, and the water-bursting risk is higher than the critical value in the water control requirement of a coal mine.
In order to ensure smooth stoping of two working surfaces, a special drainage roadway is constructed in a mine, as shown in figure 3, the elevation of a bottom plate of the drainage roadway is-541.9 to-540.7 m, the total length is 390m, according to hydrological exploration reports, the thickness of a 1-4 gray aquifer in a mining area is 50m, the permeability coefficient K is 0.03m/d, the water storage coefficient is 1 multiplied by 10 < -6 >, the radius rw of a drainage hole is 0.05m, and the maximum descending depth Smax of a single hole is 490m.
S1, in an actual water discharging project, taking a boundary covering a mining working face range as a thinning boundary, and selecting a working face end point in the thinning boundary as a water level control point, as shown in figure 1.
S2:1-4 ashes have typical high pressure-bearing and low permeability characteristics. According to the principle of selecting water level control points, the ends of the upper and lower roadways far away from the drainage drilling holes and having larger burial depth are used as control points, as shown in fig. 3, each control point is used as a water level observation point, the water pressure born by the bottom of the water-resisting layer of the coal seam bottom plate is observed, namely z=0, and meanwhile d=0 of the drainage drilling holes is caused. For the convenience of calculation, the lower left corner of the attached figure 3 is taken as an origin of coordinates, the relative coordinates of each control point are obtained, the critical water burst coefficient of the working surface is 0.06MPa/m according to the water control requirement of the coal mine, and the safe water pressure of the control point is 2.7MPa; the safe water head elevation of the control point and the safe water level drop of each control point can be obtained according to the water head formula, and the safe water level drop of each control point is shown in table 2.
TABLE 2 safe water level control point Water level drop
S3: the drainage drill hole is to be arranged in the AB section of the roadway, and according to the coordinates of the two points A (2008.42, 582.83) and B (2146.8, 408.48), the roadway can be generalized into a linear equation: y= -1.23x+3057.4 (2008.42. Ltoreq.x. Ltoreq. 2146.8).
S4: by using the established optimization model and applying a multi-objective particle swarm optimization algorithm, based on Matlab software, the calculation result is shown in a table 3, and fig. 4 is a solution which is given by taking a complete well as an example and meets constraint conditions, and the program gives a final result according to the optimization targets with small hole number and small single-hole flow and the principle of minimum total flow.
TABLE 3 optimization of solution results
S5: and (3) solving the optimal hole number and single-hole flow value of the model by using a multi-objective optimization method.
S6: as can be seen from table 3, as l/M decreases (the extent of drilling through the aquifer), n gradually increases, and the magnitude of the increase gradually increases, the single hole flow gradually decreases, the total flow is not greatly different, and the total drilling engineering amount shows a stepwise decreasing trend; aiming at the heterogeneous aquifer with low permeability, the better dredging effect can be achieved through encryption drilling and single-hole small flow; however, when the single-hole flow is small, the problems of more holes, high construction cost and the like exist; meanwhile, the aquifer is a composite aquifer consisting of 1-4 ash, generally 3-4 ash has better water-rich property, and if l/M is smaller, the problem that a water drain hole is difficult to enter 3-4 ash exists; according to the optimized calculation result, when l/M=0.6, the hole number and drilling engineering quantity are moderate, and the total water discharge quantity is minimum, so that the water discharge design scheme is ideal.
The mine refers to an optimized result in the actual water drainage engineering design, adopts a non-complete well scheme, simultaneously reduces single-hole flow, properly encrypts water drainage holes and the like to solve the problem of the drainage of a heterogeneous low-permeability limestone aquifer, and arranges 6 water drainage holes penetrating through layers in two drilling sites of a water drainage roadway, as shown in figure 5; except that the F1-2 hole terminal holes are in three ashes, the rest 5 water drain hole terminal holes are all in four ashes; shan Kongfang the water quantity is concentrated at 52m 3 /d-100m 3 In addition, 4 approximately horizontal bedding water discharging holes are respectively constructed along azimuth angles of 170 degrees, 196 degrees, 206 degrees and 222 degrees in a water discharging lane No. 3 drill site to better achieve the dredging effect, and the water discharging holes are basically flatRunning in four gray runs, the average length is 140m.
As shown in FIG. 6, the total discharge of the lime in the 101 mining area is 50m 3 And/h, accumulating the dredged limestone water for about 49 ten thousand m 3 . The water level of the ground ash observation hole 14 view 1 (outside the exposure of the mining area) is reduced from-50 m to-170 m, the accumulated reduction is 120m, and the maximum daily reduction is 2.4m; the underground pressure measurement of the working face is Kong Shuiya 0.2.2 MPa, the corresponding water level is-320 m, the elevation of the lowest point of the extraction section of the working face is-401.1 m, and the maximum water bursting number of the working face is 0.026, so that the aim of drainage extraction is basically achieved.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.