CN118187862A - Water-retention coal mining partitioning method for coal seam roof aquifer - Google Patents
Water-retention coal mining partitioning method for coal seam roof aquifer Download PDFInfo
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Abstract
The invention discloses a water-retention coal mining partitioning method for a roof aquifer of a coal seam, which takes a typical water-retention coal mining working face as an evaluation object, adopts different standards for up to 4 times continuously to perform post-evaluation on the water-retention coal mining partitioning mode of the roof aquifer of the coal seam in a coal mine area, and mainly comprises the following steps: the method comprises the steps of (1) partitioning according to a comparison result of mine water inflow Q z and water inflow threshold Q max, (2) partitioning according to whether an disappeared aquifer exists above the disappeared aquifer of the first water level, (3) partitioning according to a comparison result of a water enrichment coefficient Q b of the aquifer of a coal mining area and a water enrichment coefficient Q y of a coal mining unaffected area, and (4) partitioning according to a comparison result of a fresh weight sample variance S 1 of a vegetation root system above a goaf and a fresh weight variance S 2 of a dominant vegetation root system of the non-coal mining area. The invention considers the system engineering of different coal mines, including seepage in the water diversion fracture zone, long-term overflow and the positive measures of mining areas of the coal mine for water retention coal mining, and is more comprehensive, systematic and advanced.
Description
Technical Field
The invention relates to the technical fields of hydrogeology and mining engineering, in particular to a water-retaining coal mining partitioning method for a roof aquifer of a coal seam.
Background
The ecological environment in northwest areas of China is fragile, but the coal resources are rich, the influence of coal exploitation on the ecological environment is great, and the water-retention coal mining work needs to be carried out. In the water-retention coal mining work, the subareas are generally required to be carried out according to mining geological conditions, and then different subareas adopt different water-retention coal mining methods to carry out protective measures. The traditional water-retention coal mining partitioning method taking a roof aquifer as a target mainly comprises a partitioning method taking the height of a water guide fracture zone as a reference, a partitioning method taking the water resource damage amount as a reference and a partitioning method taking the geological hydrogeological condition of mining engineering as a reference, and has the following problems:
(1) The drilling data are used as partition basic data, but the span of an actual coal mining working face is large, the representativeness of the data on points is not strong, certain randomness exists, and the partition precision is not high.
(2) Only the direct influence of coal exploitation on the aquifer is considered, indirect drainage water is not considered, and the conditions of overflow, lateral replenishment and the like are not strong in adaptability.
(3) Different coal mining methods can be selected for different coal mines, disturbance of the different coal mining methods to the aquifer is different, and the traditional partitioning method is not combined with the coal mine production system partition, so that the implementation effect is poor.
(4) The water-retaining coal mining is also a system engineering, not only protecting the water level, but also combining with protecting vegetation, and the traditional partition only takes the water level as a standard and is not comprehensive.
Disclosure of Invention
The invention aims to: in order to overcome the defects in the prior art, the invention provides a water-retention coal mining partition method for a roof water-bearing layer of a coal seam, which considers the system engineering of different coal mines, comprises the factors of seepage in a water-guiding fracture zone, long-term overflow and the like, adopts up to 4 judgment standards in a layer-by-layer progressive manner, divides the water-retention coal mining partition of the roof water-bearing layer of the coal seam into 3 partition types, and further provides positive measures of mining areas of the coal mine for water-retention coal mining on the basis, and is more comprehensive, systematic and advanced.
The technical scheme is as follows: in order to achieve the above purpose, the invention adopts the following technical scheme:
the invention aims to provide a water-retaining coal mining partitioning method for a roof aquifer of a coal seam, which comprises the following steps of:
S1, selecting a typical water-retention coal face for trial mining, and carrying out first partition according to the comparison result of the mine water inflow Q z and the water inflow threshold Q max, wherein the method specifically comprises the following steps of,
If Q z＜Qmax is detected, judging the area of the coal mine as a water-retaining coal mining type I partition, otherwise, continuing to step S2;
s2, drilling a goaf on the ground of the working surface from top to bottom, recording a first water level disappeared aquifer, and carrying out a second partition according to whether the first water level disappeared aquifer exists or not, wherein the method specifically comprises the steps of,
If no unresolved aquifer exists above the first water level disappeared aquifer, judging the area of the coal mine as a water-retaining coal mining type III partition, otherwise, continuing to step S3;
S3, in the goaf drilling of the first water level non-vanishing aquifer, performing a complete well pumping test above the goaf to obtain a water-rich coefficient q b of the aquifer in the coal mining area, and performing a third partition according to a comparison result of the water-rich coefficient q b of the aquifer in the coal mining area and the water-rich coefficient q y of the coal mining non-affected area,
If q b＜0.5qy is detected, judging the area of the coal mine as a water-retaining coal mining type III partition, otherwise, continuing to step S4;
s4, carrying out fourth partitioning according to the comparison result of the fresh weight sample variance S 1 of the vegetation root system above the goaf and the fresh weight variance S 2 of the dominant vegetation root system in the non-coal mining area, wherein the method specifically comprises the steps of,
If S 1＞1.5S2, the area of the coal mine is judged to be the water-retaining coal mining type III partition, otherwise, the area is judged to be the water-retaining coal mining type II partition.
The invention adopts different reference standards for up to 4 times to judge the water-retaining coal mining partition mode of the roof aquifer of the coal seam, and is mainly based on the following steps:
(1) First partition: partitioning is carried out according to the comparison result of the mine water inflow Q z and the water inflow threshold Q max, the coal mining water filling intensity is considered, when the mine water inflow is smaller than the 180m 3/h threshold which is considered to be simple in hydrogeology condition currently in the industry, the water filling aquifer is considered to be natural and not rich in water (does not need important protection), the water filling aquifer is divided into I-type partitions, otherwise, the water filling aquifer is considered to be natural and rich in water (needs important protection), and further judgment is needed;
(2) Second partition: partitioning according to the existence of the disappeared aquifer above the first water level disappeared, wherein the range of coal mining influence is considered, namely when the aquifer above the first water level disappeared does not exist, the fact that all the aquifer on the top plate is lost is indicated, the coal mining disturbance degree is maximum, the partition is divided into III type partitions, otherwise, a certain water resource is not completely disturbed by coal mining engineering, and the partition is needed;
(3) Third partition: partitioning according to the comparison result of the water-rich coefficient q b of the aquifer in the coal mining area and the water-rich coefficient q y of the unaffected area of the coal mining, wherein the influence degree of the coal mining on the roof water is considered, namely, when the change of the water-rich coefficient exceeds a threshold value, the influence degree of the coal mining on the roof water is indicated to be a III type partition, otherwise, the partition needs to be further judged;
(4) Fourth partition: the classification is carried out according to the comparison result of the fresh weight sample variance S 1 of the vegetation root system above the goaf and the fresh weight variance S 2 of the dominant vegetation root system in the non-coal mining area, the ecological response degree after the influence of coal mining on roof water is considered, namely, the ecological obvious degradation is classified into a type III classification, and otherwise, the classification is classified into a type II classification.
In one embodiment of the present invention, in step S1, the typical water-retaining coal face satisfies:
a. the coal mining method is used for forming the working face type with the largest height of the caving zone in the coal mining method, and/or
B. the dominant vegetation type of a typical water-retaining coal face ground is the most covered vegetation type, and/or
C. The ratio of the average first-mining coal layer thickness to the burial depth of the coal face is the largest compared with other coal faces.
Further, in one embodiment of the present invention, the dominant vegetation type refers to a vegetation type having a coverage of 50% or more of the surface of the first step coal face.
In one embodiment of the invention, in step S1, the water inflow Q and the mining area F of the working surface are recorded each time the mine is pressed during the mining process.
In one embodiment of the present invention, in step S1, the test method includes: recording the water inflow Q and the mining area F of the working face, constructing a linear equation of the water inflow Q and the mining area F by adopting data fitting, substituting the total area F z of the coal mine into the linear equation, and predicting and evaluating the water inflow Q z of the mine when the whole coal mine is mined.
Further, in one embodiment of the invention, the water inflow Q and the mining area F of the face are recorded each time the mine is pressed during the mining process.
In one embodiment of the invention, in step S1, the water inflow threshold value Q max＝180m3/h is set. The industry currently considers that the water inflow below 180m 3/h belongs to the mine hydrogeology type simple (national standard), and considers that the disturbance of coal mining on water is small.
In one embodiment of the present invention, in step S2, the goaf drilling is at least 20 meters away from the horizontal distance of the transport roadway and the track roadway of the typical water retention coal face, and at least 50 meters away from the horizontal distance of the open cut and the collection line. Considering that the maximum area of the coal mining disturbance range is in the range, relevant current industry standards prescribe that goaf drilling positions need to meet the requirements.
In one embodiment of the present invention, in step S2, the first water level disappeared aquifer is recorded, and the first water level disappeared aquifer and the drill hole sections below are sealed.
In one embodiment of the present invention, in step S2, if there is an unresponsive aquifer above the first water level disappeared, the first water level unresponsive aquifer above the first water level disappeared is retained, and all other intervals are sealed.
The hole sealing is to cut off the influence of the artificial drilling channel on the test in order to perform the water-rich number test later. In addition, the hole sealing reduces the influence on mine safety even if the test is not performed.
In one embodiment of the present invention, in step S3, the method for testing the water-rich coefficient q y of the unaffected coal mining area includes: and (3) performing a drilling hole outside the working surface, and performing a complete well pumping test to obtain the water-rich coefficient q y of the unaffected coal mining area.
Further, in one embodiment of the present invention, the implementation of a borehole outside the face means that a borehole is implemented at a horizontal distance 2R and above outside a typical water retention coal face, wherein,S is the water level height of the water-bearing layer with the first water level disappearing, and K is the permeability coefficient of the water-bearing layer with the first water level not disappearing. R is an influence radius, 2R is the limit of the mutual influence of two drilling holes, and in order to prevent interference, the drilling hole positions are arranged at the horizontal distance 2R and above outside a typical water-retaining coal face.
In one embodiment of the invention, the maximum primary water level drop during the pumping test is greater than 0.8 times the thickness of the aquifer of the pumping test. In the non-coal mining area, the ratio is generally 0.5, the influence of coal mining needs to be repeatedly considered, the value is further increased, and 0.8 is an actual empirical value, and if not suitable, the ratio can be considered to be more than 0.5.
In one embodiment of the present invention, in step S4, the method for testing the variance S 1 of the fresh weight sample of the vegetation root system above the goaf includes: 3 dominant vegetation in the coal pillar area of the coal face is selected, 3 dominant vegetation in the range of 5 meters near the open-cut hole, 3 dominant vegetation in the range of more than 50 meters from the open-cut hole and the harvest line at the center line position of the goaf, 9 samples of the above 3 areas are taken to measure the fresh weight of the vegetation root system, and a fresh weight variance sample S 1 of the vegetation root system above the goaf of the typical water-retaining coal face is calculated.
Further, in one embodiment of the present invention, 3 plants of the dominant vegetation are located at the goaf centerline and within 50-100 meters from the cut and harvest line.
In one embodiment of the present invention, in step S4, the method for testing the variance S 2 of the fresh weight sample of the vegetation roots in the non-coal mining area includes: and sampling 9 dominant vegetation samples at a position which is more than the horizontal distance w from the typical water-retaining coal face, measuring the fresh weight of the vegetation root system, and calculating a fresh weight variance sample S 2 of the vegetation root system in the non-coal-mining area, wherein w=tan alpha×D, alpha is the crack angle of the typical water-retaining coal face, and D is the burial depth of the first-coal seam.
Further, in one embodiment of the invention, samples are taken at a horizontal distance w-2 w from the typical water-retaining coal face.
In one embodiment of the present invention, the adjustment and selection of the coal mining method are performed according to different water-retention coal mining partitions, specifically including:
if the water-retaining coal mining type I subarea is adopted, normal mining is carried out, and a water-retaining coal mining technology is not needed;
(ii) if the water-retention coal mining type II subarea is adopted, the ecological environment of coal mining is generally disturbed, the coal mining intensity is required to be reduced, and/or the coal mining height is reduced, and/or the mining speed is improved, and/or the layered mining is required to be carried out;
(iii) if the water-retaining coal mining type III partition is a serious disturbance of the ecological environment of coal mining, changing the coal mining method, and continuing to evaluate the partition for the second time until the water-retaining coal mining type I partition or the water-retaining coal mining type II partition is reduced.
Further, in an embodiment of the present invention, the changing the coal mining method includes changing to filling mining, reconstructing a water-proof layer, or grouting a separation layer, etc.
The beneficial effects are that: compared with the prior art, the invention has the beneficial effects that:
1) Simple and easy to implement: directly taking typical working face test exploitation as an evaluation data source, and carrying out exploitation and evaluation simultaneously;
2) The implementation effect is good: the evaluation subareas are developed based on mining engineering of the coal mine system;
3) The cost is less: a large amount of drilling exploration does not need to be carried out, and the number of the drilled holes is obviously reduced;
4) The implementation period is shorter: the partition is developed while coal is mined, so that a great amount of drilling and exploration projects do not need to be developed in the early stage;
5) More comprehensive: and developing an evaluation partition according to two standards of water resources and ecological environment.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
The invention will be further described with reference to the drawings and examples. The invention will be better understood from the following examples. However, it will be readily understood by those skilled in the art that the specific material ratios, process conditions and results thereof described in the examples are illustrative of the present invention and should not be construed as limiting the invention described in detail in the claims.
Examples
As shown in fig. 1, a roof water-retention coal mining partitioning method comprises the following steps:
S1, selecting a typical water-retention coal face for trial mining, and carrying out first partition according to a comparison result of mine water inflow Q z and a water inflow threshold Q max, wherein the method comprises the following steps:
Step one: and selecting a typical water-retaining coal face for trial mining.
The typical water-retaining coal face is that a mining area is divided into different coal mines according to the coal mine right boundary, and each coal mine selects 1 typical water-retaining coal face.
In some examples, this working surface should meet the following conditions:
Firstly, the adopted coal mining method is a working face type with the largest height of a caving zone formed in the coal mining method (if the coal mining method is only one coal mining method, comparison is not needed, and if a plurality of coal mining methods exist, a coal mining method with the largest height of the caving zone is determined by adopting a preset numerical simulation method);
Second, on the first basis, the dominant vegetation type of the ground of the typical water-retention coal face (the dominant vegetation type refers to the vegetation type with a coverage area accounting for 50% or more of the ground surface of the first-step coal face) is the vegetation type with the most coverage area;
third, on the first and second basis (i.e., the face of the optimum vegetation type and maximum-span drop height coal mining method), the ratio of the average first-seam thickness to the burial depth of the coal face is the greatest than other coal faces.
Step two: and (3) finishing typical water-retention coal mining working face trial mining, and fitting and constructing a linear equation of the coal mining area F and the water inflow Q.
In some examples, this face water inflow Q and the area of mining F are recorded during mining, with each mine tap observation being Qn and Fn, n being the number of mine taps. And (3) constructing a linear equation of the coal mining area F and the water inflow Q by adopting data fitting, wherein Q=aF+b, and a and b are fitting coefficients.
Step three: and (3) predicting the mine water inflow quantity Q z＝aFz +b when the whole coal mine is mined according to the linear equation determined in the step two, wherein F z is the total area of the coal mine and is obtained through coal mine design.
In some examples, a water inflow threshold Q max＝180m3/h is selected.
Step four: when Q z＜180m3/h, the area of the coal mine is judged to be the water-retaining coal mining type I partition. When Q z≥180m3/h, then the following step determination is made.
S2, goaf drilling is carried out on the ground of the working face from top to bottom, a first water level disappeared aquifer is recorded, and a second partition is carried out according to the existence of the first water level disappeared aquifer and the existence of the non-disappeared aquifer, specifically, the method comprises the following steps:
step five: goaf drilling is performed on the ground of a typical water-retaining coal face of Q z≥180m3/h from top to bottom.
In some examples, the goaf borehole is at a horizontal distance of 20 meters and above from the transport and rail lanes of a typical water-retaining coal face and at a horizontal distance of 50 meters and above from the open cut and the setback.
In some examples, goaf drilling is performed to record the first water level disappeared aquifer, and the first water level disappeared aquifer and the drilling sections below are sealed, the first water level non-disappeared aquifer above the first water level disappeared aquifer is reserved, and all other intervals are sealed.
If there is no unconsolidated aquifer above the first water level disappeared aquifer, the coal mine is determined to be a water-retaining coal mining type III partition. Otherwise, the following step determination is performed.
S3, in the goaf drilling of the water-bearing layer with the first water level not disappeared, performing a complete well pumping test above the goaf to obtain a water-bearing layer water-rich coefficient q b of the coal mining area, and performing a third partition according to a comparison result of the water-bearing layer water-rich coefficient q b of the coal mining area and the water-rich coefficient q y of the coal mining unaffected area, wherein the method specifically comprises the following steps six to eight:
Step six: and (3) carrying out a complete well pumping test above the goaf in the goaf drilling implemented in the step (five) on the aquifer with the first water level not disappeared to obtain a water-rich coefficient q b of the aquifer in the coal mining area.
In some examples, where the maximum primary water level drop during the pumping test should be greater than 0.8 times the aquifer thickness of the pumping test, the remainder of the procedure is performed in accordance with current techniques.
Step seven: and D, carrying out drilling on the water-bearing layer with the first water level not disappeared in the step five at a position with a horizontal distance of 2R and above outside a typical water-retaining coal face, and obtaining the water-rich number q y of the coal-mining unaffected region by adopting the method of the step six.
In some examples, whereinS is the water level height of the first water level disappeared water-bearing layer determined in the step five, the water level height is obtained through hydrogeological investigation in the coal mine exploration stage, K is the permeability coefficient of the first water level disappeared water-bearing layer, and the water level height is obtained through hydrogeological test in the coal mine exploration stage.
Step eight: and when q b＜0.5qy is reached, judging the coal mine as a water-retaining coal mining type III partition. When q b≥0.5qy, the following steps are performed for further determination.
S4, partitioning for the fourth time according to a comparison result of the fresh weight sample variance S 1 of the vegetation root system above the goaf and the fresh weight variance S 2 of the dominant vegetation root system in the non-coal mining area, wherein the method comprises the following steps:
Step nine: fresh weight weighing is carried out on root systems of ground dominant vegetation of the typical water-retaining coal face mining for more than 1 year, and a fresh weight sample variance S 1 of the root systems of the vegetation above the goaf is obtained.
In some examples, 3 dominant vegetation in the range of 5 meters near the open cut eye and 3 dominant vegetation in the range of 50 meters above the open cut eye and the harvest line are selected, 9 samples of the 3 areas are taken to measure the fresh weight of the vegetation root system, and the variance S 1 of the fresh weight of the vegetation root system on the goaf of the typical water-retaining coal face is calculated.
Step ten: and measuring fresh weight variance S 2 of vegetation roots in the non-coal mining area at a position which is more than horizontal distance w from the typical water-retaining coal mining working surface, and sampling 9 plants to obtain a weighing difference value.
In some examples, where w=tan α×d, α is the fracture angle of a typical water retention coal face, obtained by field measurements; d is the burial depth of the first-production coal seam.
When the difference between S 1 and S 2 is greater than 0.5, S 2, namely S 1＞1.5S2, the coal mine is judged to be a water retention coal mining type III partition, otherwise, the coal mine is judged to be a water retention coal mining type II partition.
Step eleven: the coal mining method is adjusted and selected according to different water-retaining coal mining subareas, and specifically comprises the following steps:
if the type I partition is water-retaining coal mining, normal mining is carried out, and the water-retaining coal mining technology of the mining area is not needed.
(Ii) if the water-retention coal mining type II subarea is adopted, the ecological environment of coal mining is generally disturbed, the coal mining intensity needs to be reduced, and/or the coal mining height is reduced, and/or the mining speed is improved, and/or the layered mining is carried out.
(Iii) if the water retention coal mining type III partition is a serious disturbance to the ecological environment of coal mining, the coal mining method needs to be thoroughly changed, in some examples, the method is changed into a filling mining mode and the like, and after the change, the secondary evaluation partition is carried out until the water retention coal mining type I partition or the water retention coal mining type II partition is reduced. The coal mining method is changed into filling mining, water-resisting layer reconstruction or separation layer grouting.
Compared with the traditional technology, the method for partitioning the water-retention coal mining of the roof aquifer of the coal seam has the following innovation:
First, the conventional partition is mainly pre-evaluation, i.e. prediction, and the result is difficult to be accurate due to the fact that the rock and soil mass is difficult to fully detect. The invention is mainly post-evaluation, and the key of the post-evaluation is that the following is 3 points:
(1) Typical water-retention coal mining working surfaces are subjected to trial mining, and the coal mining method, vegetation types and coal-water spatial relationship of the working surfaces have great contribution to results. Therefore, the invention selects the working face with the largest influence by restraining 3 layers on the typical water-retention coal mining working face through the three-zone theory, the ecologically suitable water level theory and the mining seepage theory on the coal mine.
(2) Regarding the post evaluation of the influence of water resources after coal mining, the change of ecological water level is paid attention to in the traditional method, the rich water is paid attention to, and the rich water of the aquifer not only comprises the permeability change of the aquifer, but also comprises the characteristic of the replenishing capability of the aquifer, so that the method is more comprehensive. Because the water resource is necessarily dredged in coal exploitation and seepage is necessarily generated, the maximum primary water level drop depth is more than 0.8 times of the thickness of the aquifer in a water pumping test, and the aquifer after coal mining is evaluated more comprehensively.
(3) Regarding the post evaluation of the influence of vegetation after coal mining, the change of fresh weight of the root system of the same type of vegetation in a water-deficient area directly represents the growth condition of the vegetation, and the control rule of mine pressure and rock stratum is considered in the area where the vegetation is sampled in a goaf, wherein the surface mining of the area with larger fracture inevitably leads to the loss of water resources, so that the evaluation is typical.
Secondly, the traditional subareas take the water guiding fracture zone as a prediction basis, and the invention considers the system engineering of different coal mines, including factors such as seepage in the water guiding fracture zone, long-term overflow and the like. And on the basis, the invention further provides positive measures of mining areas of the coal mine for water retention coal mining, so that the system is more comprehensive and advanced.
Example 1:
The water-retaining coal mining is partitioned before the mining of the period 1 of a large mining area, but the actual partitioning effect is influenced by factors such as a coal mining method, vegetation difference, water-bearing layer overflow and the like, and the evaluation result has larger deviation from the actual occurrence, so that the water-retaining coal mining partitioning method for the water-bearing layer of the roof of the coal seam is adopted for more accurately evaluating the mining-space geological condition partition of the mining area for the mining period 3, and comprises the following specific steps:
Step one: and selecting a typical water-retaining coal face for trial mining.
The typical water-retention coal face is to divide a mining area into different coal mines according to the coal mine right boundary, and the mining area is divided into 14 coal mines, and in the embodiment, 1 coal mine is taken as an example for evaluation. Each coal mine selects 1 typical water-retention coal face, and the face meets the following conditions:
Firstly, the coal mine of the embodiment has only one coal mining method, namely comprehensive mechanized mining, and the coal mining method which is adopted is the type of a working surface with the largest height of a caving zone formed in the coal mining method of the coal mine;
Secondly, on the basis of the first, the dominant vegetation type of the ground of the typical water-retention coal face (the dominant vegetation type refers to the vegetation type with the coverage area accounting for 50% or more of the ground surface of the first-step coal face, namely caragana microphylla) is the vegetation type with the maximum coverage area, and in the embodiment, the caragana microphylla is specific;
thirdly, on the basis of the first and the second (namely, the working surface of the optimal vegetation type and the maximum cross-falling zone height coal mining method), the ratio of the average first coal seam thickness and the buried depth of the coal mining working surface is the largest compared with other coal mining working surfaces, and the maximum thickness-depth ratio in the embodiment is 1:32, and a work surface 2201.
Step two: the typical water retention coal mining face test mining is completed, and the face water inflow Q and the mining area F are recorded in the mining process.
In this embodiment, qn and Fn are observed once for each mine pressure, and n is the number of mine pressures. And (3) constructing a linear equation of the coal mining area F and the water inflow Q by adopting data fitting, wherein Q=aF+b, and a and b are fitting coefficients. The fitted linear equation is q=34f+104.
Step three: substituting the total coal mine area F z＝24.79km2 obtained through coal mine design into the linear equation according to the linear equation determined in the step two, and predicting the mine water inflow Q z＝34Fz+104＝947m3/h when the whole coal mine is exploited.
Step four: due to Q z＞180m3/h, the following step determination is made.
Step five: the goaf drilling is implemented on the ground of the typical water-retaining coal face from top to bottom. The goaf drilling distance is typically 45-165 m from the horizontal distance between the water-retaining coal face transport roadway and the track roadway and 104 m from the horizontal distance between the open-cut hole and the working line.
The goaf drilling is implemented to record the first water level disappeared aquifer (Yan' an group aquifer), and the first water level disappeared aquifer and the drilling sections below the first water level disappeared are sealed, the first water level non-disappeared aquifer (straight Luo Zu aquifer) above the first water level disappeared aquifer is reserved, and all other layers are sealed.
Step six: and (3) carrying out a complete well pumping test above the goaf in the goaf drilling implemented in the step (five) on the aquifer with the first water level not disappeared in the step (five) to obtain the aquifer water-rich coefficient q b = 0.019 liters/(second meter) of the coal mining area.
In the water pumping test process, the maximum primary water level drop is 0.84 times of the thickness of the water-bearing layer of the water pumping test, and the rest operation methods are executed according to the current technology.
Step seven: for the aquifer with the first water level not disappeared in the step five, a drilling is carried out at a position of 50 meters above the horizontal distance 2R outside the typical water-retaining coal face, and the water-rich number q y = 0.024 liters/(second meter) of the coal-mining uninfluenced region is obtained by adopting the method of the step six.
Wherein the water level height S=2.2 meters of the water-bearing layer with the first water level disappearing determined in the step five is obtained through hydrogeological investigation in the coal mine exploration stage, the permeability coefficient K=1.2 meters/day of the water-bearing layer with the first water level disappearing is obtained through hydrogeological test in the coal mine exploration stage, and accordingly,And (5) rice.
Step eight: due to q b≥0.5qy, the following steps are performed for further determination.
Step nine: fresh weight weighing is carried out on root systems of ground dominant vegetation of the typical water-retaining coal face mining for more than 1 year, and a fresh weight sample variance S 1 of the root systems of the vegetation above the goaf is obtained.
3 Dominant vegetation in the coal pillar area of the coal face, 3 dominant vegetation in the range of 5 meters near the open-cut hole and 3 dominant vegetation in the range of 50 meters away from the open-cut hole and the harvest line are selected, 9 samples of the 3 areas are taken to measure the fresh weight of the vegetation root system, and the variance S 1 =33.14 of the fresh weight of the vegetation root system on the goaf of the typical water-retaining coal face is calculated.
Step ten: and measuring the fresh weight variance S 2 =20.04 of vegetation roots in the non-coal mining area at a position which is 150 meters (more than 123.4 meters) away from the typical water-retaining coal mining working surface, and sampling 9 plants to weigh the difference.
The crack angle alpha=71° of the typical water-retention coal face is obtained through on-site actual measurement; the burial depth d=42.5 meters of the first seam, resulting in w=tanα×d=123.4 meters.
Since the difference (13.1) between S 2 and S 1 is greater than 0.5S 2 (10.02), the coal mine is judged to be a water retention coal mining type III partition.
Step eleven: the water-retention coal mining type III partition is a serious disturbance of the ecological environment of coal mining, the coal mining method needs to be thoroughly changed into a filling mining mode, and the secondary evaluation partition is carried out after the coal mining method is changed, so that the water-retention coal mining type I partition or type II partition is reduced.
The mining area has 7 subareas of type III and 5 subareas of type II after the evaluation of 14 coal mines in the period 3, 2 subareas of type I and 2 coal mines of the period 3 are practically tried to be mined, the evaluation result is completely consistent with the actual mining result, namely, the water-retention coal mining effect is obtained after different water-retention coal mining measures are adopted, and the phenomena of vegetation significant degradation and water resource shortage do not occur in the area.
The foregoing is only a preferred embodiment of the invention, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.
Claims (10)
1. The method for partitioning the water-retention coal mining of the roof aquifer of the coal seam is characterized by comprising the following steps of:
S1, selecting a typical water-retention coal face for trial mining, and carrying out first partition according to the comparison result of the mine water inflow Q z and the water inflow threshold Q max, wherein the method specifically comprises the following steps of,
If Q z＜Qmax is detected, judging the area of the coal mine as a water-retaining coal mining type I partition, otherwise, continuing to step S2;
s2, drilling a goaf on the ground of the working surface from top to bottom, recording a first water level disappeared aquifer, and carrying out a second partition according to whether the first water level disappeared aquifer exists or not, wherein the method specifically comprises the steps of,
If no unresolved aquifer exists above the first water level disappeared aquifer, judging the area of the coal mine as a water-retaining coal mining type III partition, otherwise, continuing to step S3;
S3, in the goaf drilling of the first water level non-vanishing aquifer, performing a complete well pumping test above the goaf to obtain a water-rich coefficient q b of the aquifer in the coal mining area, and performing a third partition according to a comparison result of the water-rich coefficient q b of the aquifer in the coal mining area and the water-rich coefficient q y of the coal mining non-affected area,
If q b＜0.5qy is detected, judging the area of the coal mine as a water-retaining coal mining type III partition, otherwise, continuing to step S4;
s4, carrying out fourth partitioning according to the comparison result of the fresh weight sample variance S 1 of the vegetation root system above the goaf and the fresh weight variance S 2 of the dominant vegetation root system in the non-coal mining area, wherein the method specifically comprises the steps of,
If S 1＞1.5S2, the area of the coal mine is judged to be the water-retaining coal mining type III partition, otherwise, the area is judged to be the water-retaining coal mining type II partition.
2. The method of claim 1, wherein in step S1, the typical water-retaining coal face satisfies:
a. the coal mining method is used for forming the working face type with the largest height of the caving zone in the coal mining method, and/or
B. The dominant vegetation type of the ground of the typical water-retaining coal face is the vegetation type of the most covered area, and/or
C. The ratio of the average first-mining coal layer thickness to the burial depth of the coal face is the largest compared with other coal faces.
3. The method according to claim 1, wherein in step S1, the testing method comprises: recording the water inflow Q and the mining area F of the working face, adopting data fitting to construct a linear equation of the water inflow Q and the mining area F, substituting the total area F z of the coal mine into the linear equation, and predicting and evaluating the water inflow Q z of the mine when the whole coal mine is mined;
in the step S1, the water inflow threshold Q max＝180m3/h is set.
4. The method of claim 1, wherein in step S2, the goaf borehole is at least 20 meters horizontally from the transport and rail lanes of a typical water retention coal face and at least 50 meters horizontally from the open cut and the firing line.
5. The method according to claim 1, wherein in step S3, the method for testing the water-rich number q y of the unaffected coal mining area comprises: and (3) performing a drilling hole outside the working surface, and performing a complete well pumping test to obtain the water-rich coefficient q y of the unaffected coal mining area.
6. The method of claim 5, wherein said drilling a borehole outside the face is performed at a horizontal distance of 2R and above outside a typical water retention coal face, wherein,S is the water level height of the water-bearing layer with the first water level disappearing, and K is the permeability coefficient of the water-bearing layer with the first water level not disappearing.
7. The method of claim 1 or 5, wherein the maximum primary water level drop during the pumping test is greater than 0.8 times the thickness of the aquifer of the pumping test.
8. The method according to claim 1, wherein in step S4, the method for testing the fresh weight sample variance S 1 of the vegetation root system above the goaf comprises: 3 dominant vegetation in the coal pillar area of the coal face is selected, 3 dominant vegetation in the range of 5 meters near the open-cut hole, 3 dominant vegetation in the range of more than 50 meters from the open-cut hole and the harvest line at the center line position of the goaf, 9 samples of the above 3 areas are taken to measure the fresh weight of the vegetation root system, and a fresh weight variance sample S 1 of the vegetation root system above the goaf of the typical water-retaining coal face is calculated.
9. The method according to claim 1, wherein in step S4, the method for testing the fresh weight sample variance S 2 of the vegetation roots in the non-mined area comprises: and sampling 9 dominant vegetation samples at a position which is more than the horizontal distance w from the typical water-retaining coal face, measuring the fresh weight of the vegetation root system, and calculating a fresh weight variance sample S 2 of the vegetation root system in the non-coal-mining area, wherein w=tan alpha×D, alpha is the crack angle of the typical water-retaining coal face, and D is the burial depth of the first-coal seam.
10. The method according to claim 1, wherein the adjustment and selection of the coal mining method are performed according to different water-retention coal mining partitions, and specifically comprises:
if the water-retaining coal mining type I subarea is adopted, normal mining is carried out, and a water-retaining coal mining technology is not needed;
(ii) if the water-retention coal mining type II subarea is adopted, the ecological environment of coal mining is generally disturbed, the coal mining intensity is required to be reduced, and/or the coal mining height is reduced, and/or the mining speed is improved, and/or the layered mining is required to be carried out;
(iii) if the water-retaining coal mining type III partition is a serious disturbance of the ecological environment of coal mining, changing the coal mining method, and continuing to evaluate the partition for the second time until the water-retaining coal mining type I partition or the water-retaining coal mining type II partition is reduced.
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