A method for grouting in different areas of upward re-mining in a lower-caving residual mining area

Abstract

The present invention belongs to the technical field of coal mining, and discloses a method for zoning grouting of upward re-mining in a lower-caving residual mining area, comprising the following steps: S1, exploring to find out the position and range of the lower-caving goaf area, and dividing the lower-caving goaf area into a suspended area and an easily dislocated area; S2, digging a transport chute and a return air chute along the bottom plate of the overlying coal seam; S3, excavating a measure lane, and drilling a grouting hole vertically to the lower-caving goaf area at a distance R from the chute in the measure lane, and the distance between adjacent grouting holes in the same measure lane is 1.3R-1.5R; S4, filling the suspended area in the lower-caving goaf area with coal gangue through a borehole, and observing through the borehole until the suspended area is filled; S5, injecting ultrafine cement grouting material into the suspended area, and injecting Marisan into the easily dislocated area. S6, arranging the working face of the overlying coal seam, and performing upward re-mining. The present invention realizes the safe and green mining of the overlying coal seam in the lower-caving residual mining area.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a subarea grouting method for upward re-mining in a lower collapse type residual mining area. Background Art

[0002] In the process of coal mining, some mining areas first mine the lower coal seams and abandon the upper coal seams due to reasons such as easy mining and difficult abandonment, mining rich and abandoning poor, mining large and abandoning small. In the past two decades, my country's coal production has maintained growth year after year, resulting in a significant decline in my country's coal geological reserves. As a non-renewable resource, coal has a very long coal formation cycle. Therefore, relying on existing theories and technologies to improve coal mining rates and mine abandoned coal resources in a green and efficient manner can guarantee the country's economic development needs and energy supply security to a certain extent.

[0003] The overlying rock strata in the mining area can be divided into three vertical zones in space: collapse zone, fracture zone and curved subsidence zone. When the upper coal is located above the regular collapse zone or fracture zone, the interlayer rock structure moves, deforms and breaks due to the mining of the lower coal seam, and the integrity of the rock structure is destroyed. There are certain safety hazards in the process of tunneling and coal excavation in the upper coal seam. After the mining of the lower coal seam, the goaf will form a suspended area and an easy-to-displacement area. With the mining of the upper coal seam, the interlayer rock structure is disturbed for the second time, which may cause the upper coal seam working face floor step to sink, and the interlayer rock structure will move, deform, break and other strong mine pressure problems, causing huge casualties and economic losses. On the other hand, the coal gangue mined during the tunneling and coal excavation of the upper coal seam is usually transported to the ground together with the coal for screening and processing, which will form a gangue mountain over time, causing harm to the environment and land. Therefore, the dislocation of gravel in the lower-caving goaf, the manifestation of strong mine pressure caused by the cutting off of the roof, and the reduction of the amount of coal gangue leaving the mine are issues that need to be comprehensively addressed for safe and green upward re-mining.

[0004] Chinese patent ZL201310458377.7 discloses a method for compacting the filling body of the goaf by grouting from the roof tunnel, which is suitable for use in mines with gangue-filled goafs. First, according to the distance of each forward excavation of the coal mining face, a group of grouting boreholes are arranged in the roof tunnel consistent with the direction of the coal mining face to the goaf, and then the height of the water-conducting fracture zone is calculated according to the equivalent mining height after the goaf is filled, and the component boreholes are filled. This method solves the problems of the goaf filled with gangue not being connected to the top, or the filling compaction is not in place, and part of the sinking space will be transferred to the surface during the mining of a single coal seam. It fails to solve the problem of rock strata movement in all collapsed goafs, and lacks prevention and control measures for strong mine pressure problems such as sinking of the bottom plate steps of the working face during upward re-mining, secondary movement, deformation, and fracture of the interlayer rock structure.

[0005] Chinese patent ZL201510116512.9 discloses a method for upward re-mining of hollow coal seams by partial filling on both sides of pillars. This invention, based on the feasibility of upward mining of hollow coal seams and the distribution of coal pillar groups and void groups in knife-pillar residual mining areas, uses a method of partial filling on both sides of pillars to protect the underlying coal pillar groups in knife-pillar residual mining areas of hollow coal seams in sequence, and gradually mines out the hollow coal resources. This patent provides a solution for partial filling on both sides of pillars in hollow mining of pillar-type goafs, but does not solve the problem that the floor of the upper layer of the residual coal in the lower collapse-type goaf may sink in steps, and lacks an effective solution for handling coal gangue during the production process.

[0006] Chinese patent ZL201811074503.8 discloses a method for mining coal seams left in the residual mining area of ​​knife pillars by combining cracking and filling. Based on the exploration and identification of the distribution of the residual mining area of ​​knife pillars below the empty coal seam and the location of the main key layer of the overlying rock, the patent provides a method for mining the upper key layer by injecting water into the borehole through the fracturing drill hole. The method is suitable for the safe mining of the overlying empty coal seam above the knife pillar residual mining area. The problem of the mine pressure manifestation such as the possible step-down sinking of the floor plate in the upward mining of the lower collapse-type empty coal seam, the secondary movement, deformation, and fracture of the interlayer rock structure, etc., has not been solved, and there is also a lack of effective treatment solutions for coal gangue during the production process.

[0007] In summary, the existing upward re-mining technical solutions are all based on the premise of pillar-type goafs, and none of them involve the safe and green mining of the overlying coal seams in the lower collapse goafs. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a method for zoning grouting for upward re-mining in a lower-collapsed residual mining area, which divides the lower-collapsed goaf into a suspended area and an easy-to-displacement area, and transports the coal gangue generated during the excavation of the overlying coal seam tunnel to the suspended area, and then adopts a scheme of zoning grouting to reinforce the goaf, thereby solving the problems of bottom plate step sinking, secondary movement, deformation, and fracture of interlayer rock structure during upward re-mining, and realizing safe and green mining of the overlying coal seam in the lower-collapsed residual mining area.

[0009] In order to achieve the above-mentioned invention object, the technical solution adopted is as follows:

[0010] A method for grouting in zones for upward re-mining of a lower-caving residual mining area comprises the following steps:

[0011] S1. Combine the geological data of the mine and the drilling exploration data to find out the position and size of the lower cave-in goaf relative to the overlying coal seam. According to whether the broken roof of the lower cave-in goaf is in contact with the collapsed rocks, the lower cave-in goaf is divided into a suspended area and an easy-to-displacement area;

[0012] S2, excavate the transport chute and return air chute along the bottom plate of the overlying coal seam;

[0013] S3. Starting from the direction of the cutting eye, a measure tunnel is excavated vertically in the solid coal of the working face in the transport drift and the return air drift. The measure tunnel is located above the suspended area and the easy-to-displace area. A hole is drilled vertically downward to the lower collapse-type goaf in the measure tunnel at a distance of 5m from the drift.

[0014] S4. Fill the coal gangue generated during the excavation of the transport drift, the return air drift and the measure lane into the suspended area in the lower cave-in goaf through drilling holes, and observe through drilling holes until the suspended area is filled;

[0015] S5. The grouting pipe in the suspended area is lowered along the borehole in the suspended area to the bottom of the suspended area in the lower cave-in goaf. The ultrafine cement grouting material is pumped into the grouting pipe by the grouting pump for grouting in the suspended area. Similarly, the grouting pipe in the prone-to-dislocation area is lowered along the borehole in the prone-to-dislocation area to the bottom of the prone-to-dislocation area in the lower cave-in goaf. The grouting material Marisan is quickly pumped into the prone-to-dislocation area. In order to ensure that the cracks and pores are filled densely, the grouting should be injected until no more grout is consumed, that is, the slurry height in the grouting pipe no longer decreases.

[0016] S6. When the injected slurry solidifies and the gravel in the suspended area and the prone-to-dislocation area is bonded by the grouting material to form a rock layer with bearing capacity, a through-hole is opened, the overlying coal seam working face is arranged, and upward re-mining is carried out.

[0017] As a further improvement of the present invention, in step S1, the specific method of combining the geological data of the mine and the drilling exploration data to determine the position and range of the lower cave-in goaf relative to the overlying coal seam is: by investigating the original geological data of the mine, combining the drilling exploration data, using a three-dimensional laser scanner to accurately detect the position and range of the lower cave-in goaf relative to the overlying coal seam.

[0018] As a further improvement of the present invention, in step S3, the spacing between the measure tunnels above the suspended area is 10m, the spacing between the measure tunnels above the prone-to-slip area is 30m, and the cross-sectional size of the measure tunnels is 2m×2m, which is parallel to the direction of the opening eye.

[0019] As a further improvement of the present invention, in step S3, R is the slurry diffusion radius, which is an important basis for determining the grouting drilling hole spacing. The diffusion of slurry in the coal rock mass fissures is irregular, and it increases with the increase of coal rock layer permeability, fissure width, grouting pressure, and injection time; it decreases with the increase of slurry concentration and viscosity. The size of the slurry diffusion range is usually controlled by adjusting the grouting pressure, slurry injection amount and concentration parameters.

[0020] As a further improvement of the present invention, in step S3, the selection of the spacing between grouting holes is closely related to the slurry diffusion radius. The spacing between the grouting holes should make the ranges of the two grouting holes have a certain overlap, which is smaller than 2 times of the diffusion radius. The spacing between the grouting holes in the same measure tunnel is 1.3R-1.5R, the diameter of the drill hole on the suspended area is 15cm, and the diameter of the drill hole on the easy-to-displacement area is 7.2cm.

[0021] As a further improvement of the present invention, in step S4, the particle size of the coal gangue is crushed to less than 15 cm.

[0022] As a further improvement of the present invention, in step S5, the front section of the grouting pipe on the suspended area is made of φ108mm steel flower pipe, and the front section of the grouting pipe on the easy-to-displacement area is made of φ60mm steel flower pipe, with a length of 6-8m. The grouting holes on the steel flower pipe are arranged in a pair of holes, the spacing between the grouting holes along the axis is 15cm, and the diameter of the grouting holes is 10mm. The two components of the Marisan grouting material are fully mixed in a volume ratio of 1:1 and then injected into the easy-to-displacement area.

[0023] The beneficial effects of the present invention are as follows: the present invention is suitable for upward re-mining in the lower collapse type residual mining area, and the lower collapse type goaf area is divided into a suspended area and an easy-to-displacement area, and the gangue generated during the excavation of the overlying coal seam tunnel is transported to the suspended area, and then the lower collapse type goaf area is reinforced by grouting in different areas. The selection of steel flower pipe grouting can realize layered grouting, which is conducive to the full diffusion of slurry along the cracks and pores, and the bonding of crushed stone is more firm. By bonding the crushed stone in the lower collapse type goaf area into a whole layer of rock strata with bearing capacity, the problems of sinking of the bottom plate step, secondary movement, deformation, and fracture of the interlayer rock structure during upward re-mining are solved. On the other hand, the problems of occupation of land by coal gangue accumulation and environmental pollution are solved, and the safe and green mining of the overlying coal seam in the lower collapse type residual mining area is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 This is the main view of the upward re-mining zoning grouting method in the lower cave-in goaf area;

[0026] Figure 2 The drilling arrangement diagram for the overlying coal seam floor is Figure 1 AA section view;

[0027] Figure 3 This is the drilling arrangement diagram for the middle part of the lower collapse goaf area, that is, Figure 1 BB cross-section diagram;

[0028] Figure 4This is the shape diagram of the steel flower tube;

[0029] In the figure: 1. Lower collapse goaf, 2. Overlying coal seam, 3. Grouting pipe in suspended area, 4. Grouting pipe in prone-to-dislocation area, 5. Drilling hole in suspended area, 6. Drilling hole in prone-to-dislocation area, 7. Steel flower pipe in suspended area, 8. Steel flower pipe in prone-to-dislocation area, 9. Transport drift, 10. Return air drift, 11. Cutting eye, 12. Measure tunnel, 13. Grouting eye. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0032] The following is a further explanation of the embodiment with reference to the accompanying drawings and in combination with the actual situation of a mine. Figure 1-4 As shown, the following steps are included:

[0033] S1. By investigating the original geological data of the mine and combining it with the data of drilling exploration, a three-dimensional laser scanner is used to accurately detect and determine the position and range of the lower collapse-type goaf 1 relative to the overlying coal seam 2. According to whether the broken roof of the goaf 1 is in contact with the collapsed gravel, the lower collapse-type goaf 1 is divided into a suspended area and an easy-to-displacement area.

[0034] S2, excavating a transport chute 9 and a return air chute 10 along the bottom plate of the overlying coal seam 2;

[0035] S3. Starting from the direction of the cutting eye 11, a measure tunnel 12 is excavated vertically in the solid coal of the working face in the transport drift 9 and the return air drift 10. The measure tunnel 12 is located above the suspended area and the easy-to-displacement area. A borehole is drilled vertically downward to the lower cave-in goaf 1 at a distance of 5m from the drift in the measure tunnel 12. The distance between adjacent boreholes in the same measure tunnel 12 is 6.5-7.5m. The diameter of the borehole 5 in the suspended area is 15cm, and the diameter of the borehole 6 in the easy-to-displacement area is 7.2cm.

[0036] S4. The gangue generated when excavating the transport drift 9, the return air drift 10 and the measure tunnel 12 is filled into the suspended area in the lower cave-in goaf 1 through the borehole 5, and the suspended area is observed through the borehole until it is filled.

[0037] S5, the suspended area grouting pipe 3 is lowered along the suspended area borehole 5 to the bottom of the suspended area, and the ultra-fine cement grouting material is pumped into the suspended area grouting pipe 3 by the grouting pump for grouting in the suspended area; similarly, the easy-to-displacement area grouting pipe 4 is lowered along the easy-to-displacement area borehole 6 to the bottom of the easy-to-displacement area, and the grouting material Marisan is quickly pumped into the easy-to-displacement area. In order to ensure that the cracks and pores are filled densely, the grouting should be injected until no grout is consumed, that is, the slurry height in the two types of grouting pipes does not drop any more.

[0038] S6. When the injected slurry solidifies and the gravel in the suspended area and the prone-to-dislocation area is bonded by the grouting material to form a rock layer with bearing capacity, a through-cut hole 11 is opened, the working face of the overlying coal seam 2 is arranged, and upward re-mining is carried out.

[0039] In step S3, the spacing between the measure tunnels 12 located above the suspended area is 10m, the spacing between the measure tunnels 12 located above the easy-to-displacement area is 30m, and the cross-sectional size of the measure tunnels 12 is 2m×2m, which is parallel to the opening direction.

[0040] The coal gangue particle size in step S4 should be crushed to less than 15 cm.

[0041] In step S5, the front section of the grouting pipe 3 on the suspended area is made of φ108mm steel flower pipe 7, and the front section of the grouting pipe 4 on the easy-to-displacement area is made of φ60mm steel flower pipe 8, with a length of 6-8m. The grouting holes 13 on the steel flower pipe are arranged in a pair of holes, the spacing between the grouting holes 13 along the axis is 15cm, and the diameter of the grouting holes 13 is 10mm. The two components of the Marisan grouting material are fully mixed in a volume ratio of 1:1 and then injected into the easy-to-displacement area.

[0042] The present invention provides a method for treating the gangue without it leaving the mine by filling the gangue generated by mining the overlying coal seam into the lower span-type goaf below, which can effectively solve the problems of environmental pollution, land occupation and spontaneous combustion caused by the accumulation of gangue on the ground, and realize safe and green mining.

[0043] The present invention divides the lower span goaf into zones and selects different grouting materials and grouting processes for different zones, thereby solving the problems of large material consumption and poor grouting effect.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, component splitting or combination, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for grouting in zones of upward re-mining in a lower-caving residual mining area, characterized in that: The following steps are involved: S1. Combine the geological data of the mine and the drilling exploration data to find out the position and size of the lower cave-in goaf relative to the overlying coal seam. According to whether the broken roof of the lower cave-in goaf is in contact with the collapsed rocks, the lower cave-in goaf is divided into a suspended area and an easy-to-displacement area; S2, excavate the transport chute and return air chute along the bottom plate of the overlying coal seam; S3. Starting from the direction of the cutting eye, a measure tunnel is excavated vertically in the solid coal of the working face in the transport drift and the return air drift. The measure tunnel is located above the suspended area and the easy-to-displace area. A hole is drilled vertically downward to the lower collapse-type goaf in the measure tunnel at a distance of 5m from the drift. S4. Fill the coal gangue generated during the excavation of the transport drift, the return air drift and the measure lane into the suspended area in the lower cave-in goaf through drilling holes, and observe through drilling holes until the suspended area is filled; S5. The grouting pipe in the suspended area is lowered along the borehole in the suspended area to the bottom of the suspended area in the lower cave-in goaf. The ultrafine cement grouting material is pumped into the grouting pipe by the grouting pump for grouting in the suspended area. Similarly, the grouting pipe in the prone-to-dislocation area is lowered along the borehole in the prone-to-dislocation area to the bottom of the prone-to-dislocation area in the lower cave-in goaf. The grouting material Marisan is quickly pumped into the prone-to-dislocation area. In order to ensure that the cracks and pores are filled densely, the grouting should be injected until no more grout is consumed, that is, the slurry height in the grouting pipe no longer decreases. S6. When the injected slurry solidifies and the gravel in the suspended area and the prone-to-dislocation area is bonded by the grouting material to form a rock layer with bearing capacity, a through-hole is opened, the overlying coal seam working face is arranged, and upward re-mining is carried out.

2. A method for upward re-mining of a lower collapse type residual mining area according to claim 1, characterized in that: In step S1, the specific method of combining the geological data of the mine and the drilling exploration data to determine the position and range of the lower cave-in goaf relative to the overlying coal seam is: by investigating the original geological data of the mine, combining the drilling exploration data, and using a three-dimensional laser scanner to accurately detect the position and range of the lower cave-in goaf relative to the overlying coal seam.

3. A method for upward re-mining of a lower collapse residual mining area according to claim 1, characterized in that: In step S3, the spacing between the measure tunnels above the suspended area is 10m, the spacing between the measure tunnels above the prone-to-slip zone is 30m, and the cross-sectional dimensions of the measure tunnels are 2m×2m, which are parallel to the direction of the opening eye.

4. A method for upward re-mining and zoning grouting in a lower-caving residual mining area according to claim 1, characterized in that: In step S3, the selection of the spacing between grouting holes is closely related to the slurry diffusion radius. The spacing between grouting holes should make the ranges of the two grouting holes have a certain overlap and be smaller than 2 times the diffusion radius. The spacing between grouting holes in the same measure tunnel is 1.3R-1.5R, where R is the slurry diffusion radius. The diameter of the drill hole in the suspended area is 15 cm, and the diameter of the drill hole in the easy-to-displacement area is 7.2 cm.

5. The method for upward re-mining of a lower collapse residual mining area according to claim 1 is characterized in that: In step S4, the coal gangue is crushed to a particle size of less than 15 cm.

6. A method for upward re-mining of a lower collapse residual mining area according to claim 1, characterized in that: In step S5, a φ108mm steel flower pipe is used for the front section of the grouting pipe on the suspended area, and a φ60mm steel flower pipe is used for the front section of the grouting pipe on the prone dislocation area. The length is 6-8m. The grouting holes on the steel flower pipe are arranged in a pair of holes. The spacing between the grouting holes along the axis is 15cm, and the diameter of the grouting holes is 10mm. The two components of the Marisan grouting material are fully mixed in a volume ratio of 1:1 and then injected into the prone dislocation area.

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