CN115929402A - A method of transferring and storing water resources by utilizing coal mining fissure loess - Google Patents

Abstract

The invention belongs to the technical field of coal mining, and particularly relates to a method for storing water resources by loess transfer of coal mining fractures, which innovatively utilizes the sectioning of loess hydrological characteristics with larger thickness caused by coal mining, wherein a deep loess section is mainly influenced by coal mining water flowing fractures, loess has the effect of inhibiting the development of the water flowing fractures, and a better fracture weak section can be formed after a certain range is reached; the mining-induced fracture in the loess can be detected by micro-resistivity scanning imaging logging, the fracture is easier to transform in the weak section of the fracture, a relative water-resisting layer can be transformed by grouting, the loess with the fracture covered is stored in rainy seasons, the water can be continuously closed, and the water holding capacity of the loess is increased; the reformed pore fracture dual medium has better atmospheric precipitation infiltration effect and water retention property, and provides a good supply source for water storage of the underburden; by the method, self-sufficiency of available water resources in the mining area is realized, the acquisition of precious surface water is reduced, and the local fragile ecological environment is protected.

Description

A method of transferring and storing water resources by utilizing coal mining fissure loess

technical field

The invention belongs to the technical field of coal mining, and in particular relates to a method for transferring and storing water resources by using loess in coal mining fissures.

Background technique

my country's loess-covered areas are rich in coal resources, but water resources are scarce, and loess-covered mining areas generally lack available water resources. Therefore, water storage in loess-covered mining areas is the guarantee for the mining of important coal resources. In the past, the main methods to solve this problem included the method of water storage and supply in the goaf, the transfer and storage of the aquifer before coal mining, and the reconstruction of the aquifer, but there are still the following problems:

1) Using gobs to store water, water resources enter the mining system, which will inevitably be polluted to varying degrees, and the cost of water pollution control is high.

2) The transfer and storage of the aquifer before coal mining mainly transfers the groundwater above the coal seam, but the groundwater above the coal seam is limited due to poor infiltration conditions in the loess-covered area, so the amount of transfer and storage is very limited.

3) The fissure network produced by coal mining is relatively complex, and the natural self-healing time of the water-resistant layer is too long. Artificially rebuilding the water-resistant layer requires a large amount of grouting and high costs.

In addition, the storage of water resources in coal mining areas also has certain hidden dangers of water damage to coal mining. In the past, water storage methods were mainly located next to the coal mining face, and the risk factor was greater.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned problems existing in the traditional technology, and provide a method for transferring and storing water resources by utilizing coal mining fissure loess.

In order to achieve the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

A method for transferring and storing water resources using loess in coal mining fissures, comprising the following steps:

S1. Select the area with loess thickness > 30m as the transfer storage water resource area;

S2. Before coal mining, design the coal mining face;

S3. Coal mining is performed at the coal mining face, and herbaceous and shrub vegetation is planted on the ground corresponding to the coal mining face after coal mining;

S4, wait for the coal mining area to stabilize after coal mining;

S5, implement the first directional drilling in the underground roadway, the horizontal section of the first directional drilling passes through the overlying loess layer on the coal mining face described in step S2; the buried depth of the horizontal section of the first directional drilling It should be X, and the buried depth X value is determined by the micro-resistivity scanning imaging logging results implemented in the ground exploration borehole;

S6. Grouting is performed after directional drilling; the injected slurry is cement slurry, and the water-cement ratio is 1:1～1:2, until the entire drilling hole is filled;

S7. On the basis of the directional drilling in step S5, shift upward by a drilling radius, and re-implement the second directional drilling;

S8, install the filter pipe that can make the water in the loess seep into the second directional borehole in the re-implemented second directional borehole;

S9, repeat steps S5 to S8, implement a plurality of third directional drilling above the coal mining face; the horizontal distance between the horizontal sections of the third directional drilling is ≤20m;

S10. Set up an underlying aquifer replenishment system at the downhole starting point of the third directional borehole; the underlying aquifer replenishment system includes a sedimentation tank, a water pump, and a replenishment borehole; the sedimentation tank stores the water intercepted in the directional borehole and Sedimentation removes cuttings; the water pump is used to pump the clean water in the sedimentation tank into the replenishment borehole;

S11. During the rainy season, the infiltrated water resources are collected from the loess area and injected into the underlying aquifer of the coal seam, which achieves the purpose of water resource storage; when the water pressure of the aquifer on the coal seam floor is equal to the critical water pressure, the drilling replenishment is stopped; the critical water pressure The calculation method of P is shown in formula (I):

P=M×T (I)

Among them, M is the distance from the aquifer to the coal seam in m; T is the critical water inrush coefficient in MPa/m.

Further, in step S2, through the design of the coal mining face, the ground surface elevation of the cut hole and closing operation line in the coal mining face is greater than the ground surface elevation of other areas of the coal mining face.

Further, in step S4, through coal mining settlement observation, observe once a day, and when the change range of 10 consecutive observations is less than 0.01m, it is considered that the settlement has reached stability.

Further, in step S5, the micro-resistivity scanning imaging logging results refer to: in the deep two-thirds section of the loess exposed by the borehole, a fracture is detected every 1m, and the buried depth of the loess section with the lowest fracture density is X .

Further, in step S5, the horizontal section of the first directional drilling is consistent with the coal mining face, and the horizontal section is longer than the coal mining face.

Further, in step S10, the replenishment drilling is performed vertically downward from the underground of the mine, and the drilling exposes to the first aquifer 15m below the coal seam floor, and this aquifer is marked as the underlying aquifer of the coal seam.

Further, in step S10, a casing for water stop is installed above the aquifer under the coal seam, and a filter pipe is installed at the aquifer below the coal seam, and the supply borehole can inject water pumped into the coal seam through the casing pipe and the filter pipe the underlying aquifer.

Further, in step S11, the value of T is 0.06-0.10 MPa/m.

The beneficial effects of the present invention are:

1. The present invention comprehensively considers that after coal mining in the loess-covered mining area, the loess forms a pore-crack double medium. The pores have a certain water holding capacity, and the cracks have good water conductivity. The negative effect of storage, that is, the loss of water resources due to the hydraulic conductivity of the fractured medium during the rainy season, and the porous medium is not saturated, and cannot continue to supply water resources in the dry season. The innovative use of coal mining has resulted in thicker loess hydrology. The segmental nature of the characteristics, that is, the shallow loess segment has good water conductivity due to mining and tension, and is suitable as an infiltration layer for atmospheric precipitation (according to the theory of active earth pressure, this range is about 10 meters, which is exactly 30 meters thick the shallow third of the loess). The deep loess section is mainly affected by coal mining water-conducting fissures, and the loess can inhibit the development of water-conducting fissures. After reaching a certain range, a relatively weak section of fissures will be formed. Mining fractures in loess can be detected by microresistivity scanning imaging logging. The cracks in the weak segment of the cracks are easier to reform, and the relative water-resisting layer can be reformed by grouting, causing the overlying cracks to store water in the rainy season, which can be continuously healed, and the water holding capacity of the loess is increased. The transformed porous and fissure dual medium has better atmospheric precipitation infiltration effect and water holding capacity, and provides a good supply source for the water storage of the underlying formation.

2. In the coal mining subsidence area of the coal mining face, due to the high opening and closing line of the coal mining face, the precipitation collects in the coal mining compaction area, avoiding a large amount of water resources passing through the hard-to-reinforce opening and closing lines. line loss, and at the same time supporting the surface vegetation, the water storage effect is better in the rainy season.

3. The present invention uses mining fissure loess to transfer and store water resources, and the mining area realizes the self-sufficiency of available water resources, reduces the acquisition of precious surface water, and protects the local fragile ecological environment at the same time.

Of course, implementing any product of the present invention does not necessarily need to achieve all the above advantages at the same time.

Detailed ways

The technical solution will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The invention provides a method for transferring and storing water resources by using coal mining fissure loess, which is characterized in that it comprises the following steps:

S1. Select the area with loess thickness > 30m as the area for transfer and storage of water resources.

S2. Before coal mining, design the coal mining face. Through the design of the coal mining face, the ground surface elevation of the cut hole and closing operation line in the coal mining face is greater than that of other areas of the coal mining face.

S3. Coal mining is carried out at the coal mining face, and herbs and shrubs are planted on the ground corresponding to the coal mining face after coal mining.

S4. After coal mining, wait for the coal mining area to be stable; through coal mining settlement observation, observe once a day, and when the change range of 10 consecutive observations is less than 0.01m, the settlement is considered to be stable.

S5. Implement the first directional drilling in the underground roadway, and the horizontal section of the first directional drilling passes through the overlying loess layer on the coal mining face mentioned in step S2. The buried depth of the horizontal section of the first directional borehole should be X, and the buried depth X value is determined by the micro-resistivity scanning imaging logging results implemented in the ground exploration borehole. The micro-resistivity scanning imaging logging results refer to: in the deep two-thirds section of the loess exposed by the borehole, a fracture is detected every 1m, and the buried depth of the loess section with the lowest fracture density is X. The horizontal section of the first directional drilling is consistent with the coal mining face, and the horizontal section is longer than the coal mining face.

S6. Grouting after directional drilling. The injected slurry is cement slurry with a water-cement ratio of 1:1 to 1:2 until the entire borehole is filled.

S7. On the basis of the directional drilling in step S5, offset upward by one drilling radius, and re-implement the second directional drilling.

S8. Install a filter pipe in the re-implemented second directional borehole to allow the water in the loess to seep into the second directional borehole.

S9. Steps S5 to S8 are repeated to implement multiple third directional drilling above the coal mining face. The horizontal spacing between the horizontal sections of the third directional drilling is ≤20m.

S10, setting an underlying aquifer recharge system at the downhole starting point of the third directional drilling. The underlying aquifer recharge system consists of sedimentation tanks, pumps and recharge boreholes. The settling tank stores the intercepted water in the directional drilling and settles and removes cuttings. The water pump is used to pump the clean water in the sedimentation tank into the supply borehole. The replenishment drilling is carried out vertically downward from the underground of the mine. The drilling exposes to the first aquifer 15m below the coal seam floor, and this aquifer is recorded as the underlying aquifer of the coal seam. Water-stop casings are installed above the aquifer under the coal seam, and filter pipes are installed at the aquifer below the coal seam. The supply borehole can inject water pumped into the aquifer under the coal seam through the casing and filter pipe.

S11. During the rainy season, the infiltrated water resources are collected from the loess area and injected into the aquifer under the coal seam, which achieves the purpose of water resource storage. When the water pressure of the coal seam floor aquifer is equal to the critical water pressure, the borehole recharge is stopped. The calculation method of critical water pressure P is shown in formula (I):

(I)

Among them, M is the distance from the aquifer to the coal seam in m. T is the critical water inrush coefficient in MPa/m. The value of T is 0.06~0.10MPa/m.

Relevant specific embodiments of the present invention are as follows:

Example 1

In this embodiment, a certain Loess Plateau region with rich coal resources but scarce water resources is taken as an object. The Loess Plateau region needs a large amount of water resources in the process of coal development, which cannot be guaranteed. In order to mine coal resources and use the fissure loess formed by coal mining to transfer and store water resources, the specific steps are as follows:

Step 1: Select the area with a thickness of loess greater than 30 meters as the area for transfer and storage of water resources, with a total thickness of loess of 63 meters.

Step 2: Before coal mining, design the layout of the coal mining face. Through the design of the coal mining face, the surface elevation of the opening and closing line of the coal mining face is higher than that of other areas of the coal mining face. Through this design, only a small amount of atmospheric precipitation enters the goaf through the cutting eye and the closing line, and most of the other is collected in the compaction area in the middle of the coal mining face.

Step 3: Carry out coal mining at the coal mining face. After coal mining, plant herbaceous and shrub vegetation on the ground corresponding to the coal mining face. The planting of vegetation can better conserve water resources.

Step 4: Wait for the coal mining area to stabilize after coal mining. Through coal mining settlement observation, observe once a day, and when the change range of 10 consecutive observations is less than 0.01m, it is considered that the settlement has reached stability. Observation results show that after 297 days, the coal mining area has reached a stable settlement.

Step 5: Implement directional drilling in the underground roadway. The horizontal section of the directional drilling passes through the overlying loess layer on the coal mining face described in step 2. The buried depth of the horizontal section should be X=38 meters. The buried depth X value is determined by the micro-resistivity scanning imaging logging results implemented in the surface exploration borehole. The micro-resistivity scanning imaging logging results refer to: in the deep two-thirds section of the loess exposed by the borehole, a crack is detected every 1 meter, and the buried depth of the loess section with the lowest crack density is X. In addition, the direction of the horizontal section of directional drilling is consistent with the direction of the coal mining face, and the length of the horizontal section is longer than that of the coal mining face.

Step 6: Grouting after directional drilling. The injected slurry is cement slurry with a water-cement ratio of 1:2 until the entire borehole is filled.

Step 7: On the basis of the directional drilling in step 5, shift upward by a drilling radius, and re-implement directional drilling.

Step 8: Lower the filter pipe in the re-implemented directional borehole to allow the water in the loess to seep into the directional borehole.

Step 9: Repeat steps 5 to 8 to implement multiple directional drilling above the coal mining face. The horizontal spacing between horizontal sections of directional drilling is 20 meters.

Step 10: Set up the underlying aquifer recharge system at the downhole starting point of the directional drilling. The recharge system includes sedimentation tanks, water pumps and recharge boreholes. The settling tank stores the intercepted water in the directional drilling and settles and removes cuttings. The water pump is used to pump the clean water in the sedimentation tank into the replenishment borehole. The replenishment drilling is a drilling carried out vertically downward from the underground of the mine. The drilling exposes to the first aquifer below the coal seam floor 15 meters (located at 25 meters from the coal seam floor). , the filter pipe is lowered at the aquifer, and the pumped water is injected into the aquifer.

Step 11: In the rainy season, the infiltrated water resources are collected from the loess area and injected into the aquifer under the coal seam, which achieves the purpose of water resource storage. When the water pressure of the coal seam floor aquifer is equal to the critical water pressure, the borehole recharge is stopped. The critical water pressure is calculated by the formula P=M×T=1.5MPa, where M=25m is the distance from the aquifer to the coal seam. T is the critical water inrush coefficient, which is taken as 0.06MPa/m.

By using the mining fissure loess to transfer and store water resources, the mining area has achieved self-sufficiency in available water resources, reduced the acquisition of precious surface water, and protected the local fragile ecological environment.

The preferred embodiments of the invention disclosed above are only to help illustrate the invention. The preferred embodiments do not exhaust all details nor limit the invention to specific implementations. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents.

Claims (8)

1. A method utilizing coal mining fissure loess to transfer and store water resources, is characterized in that, comprises the steps: S1. Select the area with loess thickness > 30m as the transfer storage water resource area; S2. Before coal mining, design the coal mining face; S3. Coal mining is performed at the coal mining face, and herbaceous and shrub vegetation is planted on the ground corresponding to the coal mining face after coal mining; S4, wait for the coal mining area to stabilize after coal mining; S5, implement the first directional drilling in the underground roadway, the horizontal section of the first directional drilling passes through the overlying loess layer on the coal mining face described in step S2; the buried depth of the horizontal section of the first directional drilling It should be X, and the buried depth X value is determined by the micro-resistivity scanning imaging logging results implemented in the ground exploration borehole; S6. Grouting is performed after directional drilling; the injected slurry is cement slurry, and the water-cement ratio is 1:1～1:2, until the entire drilling hole is filled; S7. On the basis of the directional drilling in step S5, shift upward by a drilling radius, and re-implement the second directional drilling; S8, install the filter pipe that can make the water in the loess seep into the second directional borehole in the re-implemented second directional borehole; S9, repeat steps S5 to S8, implement a plurality of third directional drilling above the coal mining face; the horizontal distance between the horizontal sections of the third directional drilling is ≤20m; S10. Set up an underlying aquifer replenishment system at the downhole starting point of the third directional borehole; the underlying aquifer replenishment system includes a sedimentation tank, a water pump, and a replenishment borehole; the sedimentation tank stores the water intercepted in the directional borehole and Sedimentation removes cuttings; the water pump is used to pump the clean water in the sedimentation tank into the replenishment borehole; S11, during the rainy season, collect infiltrated water resources from the loess area and inject them into the underlying aquifer of the coal seam. When the water pressure of the coal seam floor aquifer is equal to the critical water pressure, the drilling replenishment is stopped; the calculation method of the critical water pressure P is as in formula (I ) as shown: P=M×T( _I ) Among them, M is the distance from the aquifer to the coal seam in m; T is the critical water inrush coefficient in MPa/m. 2. The method for transferring and storing water resources by utilizing coal mining fissure loess according to claim 1, characterized in that: in step S2, through the design of the coal mining face, the opening and closing line of the coal mining face are achieved The surface elevation of the coal mining face is greater than that of other areas of the coal mining face. 3. The method for transferring and storing water resources using coal mining fissure loess according to claim 1, characterized in that: in step S4, through coal mining settlement observation, observe once a day, when 10 consecutive observations the range of change is less than 0.01m , it is considered that the settlement is stable. 4. The method for transferring and storing water resources by using coal mining fissure loess according to claim 1, characterized in that: in step S5, the micro-resistivity scanning imaging logging results refer to: the deep part of the loess exposed in the borehole 1/3 In the second section, cracks are detected every 1m, and the buried depth of the loess section with the lowest crack density is X. 5. The method for transferring and storing water resources using loess in coal mining fissures according to claim 1, characterized in that: in step S5, the direction of the horizontal section of the first directional borehole is consistent with the direction of the coal mining face, and the horizontal section The length is greater than the strike length of the coal mining face. 6. The method for transferring and storing water resources using coal mining fissure loess according to claim 1, characterized in that: in step S10, the replenishment borehole is a borehole carried out vertically downward from the underground of the mine, and the borehole is exposed to the coal seam floor Up to the first aquifer below 15m, this aquifer is recorded as the underlying aquifer of the coal seam. 7. The method for transferring and storing water resources using coal mining fissure loess according to claim 6, characterized in that: in step S10, the upper part of the coal seam's underlying aquifer is equipped with a casing for water stop, and the coal seam's underlying aquifer The filter pipe is installed at the place, and the supply borehole can inject the pumped water into the aquifer under the coal seam through the casing pipe and the filter pipe. 8 . The method for transferring and storing water resources using loess in coal mining fissures according to claim 1 , characterized in that: in step S11 , the value of T is 0.06-0.10 MPa/m.