A method for coal pillar recovery based on fault grouting modification

Abstract

This invention discloses a coal pillar recovery method based on fault grouting modification. By grouting modification of the fault fracture zone and a portion of the aquifer near the fault, the conditions for damage to the roadway and working face by the aquifer along the water-filling channel are restricted. This transforms the structurally damaged area into a section with an intact, unfractured aquifer, allowing for the design of mining roadway layouts that are close to the fault or leave small coal pillars, thus enabling the recovery of fault-resistant, water-resistant coal pillars. After grouting modification of the fault, this invention allows the working face to be arranged closer to the fault, reducing the width of the fault coal pillar or even eliminating the need for its placement. This represents a shift in fault treatment from passively leaving coal pillars for waterproofing to actively managing mining conditions in fault-damaged areas, innovating a new approach for the safe and efficient recovery of fault coal pillars in fractured fault zones through grouting modification.

Description

Technical Field

[0001] This invention relates to a method for coal pillar recovery, and more particularly to a method for coal pillar recovery based on fault grouting modification. Background Technology

[0002] my country's natural resource structure is characterized by abundant coal, scarce oil, and limited gas, which determines coal's crucial position in primary energy. As a non-renewable resource, the rational development and utilization of coal resources has significant practical implications for economic development. With years of continuous mining, the scarcity of coal resources in mines has become increasingly apparent. However, near fault lines, there are situations where large amounts of coal are trapped in coal pillars. Extracting the coal resources accumulated near fault lines could not only create substantial economic benefits but also extend the service life of mines.

[0003] Faults, as important water-conducting channels in groundwater, can connect different aquifers, leading to anything from increased mine water inflow to serious water inrush accidents. Current regulations stipulate that coal seams separated by faults and hydraulically connected to highly water-bearing aquifers, fracture zones, or strongly water-conducting faults must have water-resistant coal (rock) pillars installed near the structure. While these pillars ensure safe mining near faults, the width of these pillars is often large due to factors such as the degree of rock fragmentation, aquifer water pressure, and the conductivity of the water-conducting channels. According to current national regulations, the minimum width is 20 meters, ultimately resulting in significant waste of coal resources. Furthermore, the technical difficulties and operational challenges of secondary coal pillar mining make coal recovery difficult. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a coal pillar recovery method based on fault grouting modification.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a coal pillar recovery method based on fault grouting modification, comprising the following steps:

[0006] By arranging grouting tunnels, grouting modifications are carried out on the fault fracture zone and the area near the fault where the aquifer is located.

[0007] After grouting modification, the conditions for the aquifer to damage the roadway and working face along the water-filling channel are restricted, and the structurally damaged area is transformed into a structurally damaged area with an intact aquitard and no fractures.

[0008] The design incorporates mining roadway layouts that are close to faults or leave small coal pillars to enable the recovery of water-resistant coal pillars from faults.

[0009] Furthermore, the grouting modification includes the following steps:

[0010] Step 1: Calculate the width of the water-resistant coal (rock) pillar of the fault, and excavate a grouting tunnel outside the width of the water-resistant coal (rock) pillar based on the calculation results;

[0011] Step 2: Determine the grouting radius and obtain the spacing between each drilling site segment based on the grouting radius;

[0012] Step 3: Arrange drilling sites in sections within the grouting tunnel, and arrange grouting boreholes for grouting reinforcement in each drilling site;

[0013] Step 4: High-pressure injection of grout into the fault fracture zone and the area near the fault aquifer through grouting boreholes to reinforce the fractured rock mass in the fault area.

[0014] Furthermore, based on the drilling and geophysical exploration of the fault's water conductivity and the stratigraphic relationship between the coal seam, fault, and aquifer, the width of the fault-resistant coal (rock) pillar is calculated.

[0015] Furthermore, by planning the working face, the grouting radius is determined on the basis of ensuring that the grouting changes the rock mass and allows for safe mining of the working face. The spacing between the sections of each drilling site is then calculated based on the grouting radius.

[0016] Furthermore, the grouting boreholes are arranged as directional inclined holes to reinforce the fault with grout; the final position of the grouting holes must reach the fault position and ensure that the grout diffusion range completely covers the fault fracture zone.

[0017] Furthermore, after the grouting modification, the grouting effect is tested to determine whether the grouting effect meets the conditions for safe production at the working face. After confirming that the conditions for safe production at the working face are met, mining roadways are arranged adjacent to faults or with small coal pillars, so as to realize the recovery of water-proof coal pillars of faults.

[0018] Furthermore, the evaluation methods for the grouting modification effect include PQt curve analysis, core sampling through inspection holes, and geophysical exploration.

[0019] This invention discloses a coal pillar recovery method based on fault grouting modification. By grouting the fault, the working face can be positioned closer to the fault, reducing the width of the fault coal pillar or even eliminating the need for its construction. This transforms fault treatment from passively leaving coal pillars for waterproofing to actively managing mining conditions in fault-damaged areas, creating a new approach for the safe and efficient recovery of fault coal pillars in fractured fault zones. This invention provides crucial technical support for the green, safe, and efficient mining of coal resources in tectonically damaged areas, enabling the exploitation and utilization of fault coal pillar resources. It also extends the service life of mines, eases the transition between mining operations, and yields significant economic and social benefits. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the tunnel layout without grouting modification of the fault.

[0021] Figure 2 This is a schematic diagram of the relationship between the roadway and the fault location after grouting modification according to the present invention.

[0022] Figure 3 for Figure 2 A schematic cross-sectional view showing the relationship between the tunnel and the fault at point I-I.

[0023] In the diagram: 1a, fault before modification; 2a, fault coal pillar; 3a, machine roadway of the working face before modification; 4a, ventilation roadway of the working face before modification; 5a, longwall face before modification;

[0024] 1. Transport uphill; 2. Track uphill; 3. Fault after modification; 4. Grouting measures roadway; 5. Machine roadway of working face after modification; 6. Ventilation roadway of working face after modification; 7. Cut-off; 8. Drilling site; 9. Grouting borehole; 10. Slurry diffusion radius at the end of the hole; 11. Area of ​​multiple coal pillars; 12. Longwall face after modification. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] To effectively address the problems of existing fault-resistant coal (rock) pillars being too wide, posing numerous technical challenges and operational difficulties in secondary mining, and resulting in large-scale waste of coal resources, reducing or even eliminating fault-resistant coal (rock) pillars in fractured fault areas through treatment has become an important approach to reduce coal resource waste.

[0027] The coal pillar recovery method based on fault grouting modification disclosed in this invention determines a safe location and excavates a grouting tunnel based on the exploration of fault water conductivity by drilling and geophysical prospecting, combined with the stratigraphic relationship between the coal seam, fault, and aquifer. By arranging a drilling site in the grouting tunnel to grout the fault fracture zone and the area adjacent to the fault in the aquifer, the structurally damaged area is transformed into a structurally damaged area with an intact aquitard and no fractures, thereby eliminating the influence of the fault as a water-conducting channel and achieving the purpose of fault coal pillar recovery through fault grouting modification.

[0028] First Figure 1 The diagram shows the roadway layout without grouting modification of the fault. In fractured fault areas, when grouting modification is not performed, according to current national regulations, water-resistant coal (rock) pillars are left to ensure the safe operation of coal seam mining near the fault; for example... Figure 1As shown, fault coal pillar 2a is a water-resistant coal (rock) pillar left for the fault. It represents unminable coal resources, and a minimum width of 20m is required. The inability to mine a large amount of fault coal pillar resources results in significant waste. Meanwhile, the distribution of the working face machine roadway 3a, the working face 5a, and the ventilation roadway 4a before grouting modification of the fault is shown in the figure.

[0029] For example Figure 2 and Figure 3 As shown, this invention illustrates the layout of the fault roadway after grouting modification. Grouting modification of the fault reinforces the fractured rock mass, essentially eliminating the threat posed by the fault as a water-conducting channel to safe mining. Based on this, the layout of the machine roadway 5 in the modified working face can be closer to the fault, achieving a reduction or elimination of fault coal pillars, significantly improving coal resource recovery. This represents a shift in fault treatment from passively leaving coal (rock) pillars for waterproofing to actively managing the mining conditions at the bottom of fault-damaged areas, innovating a new approach for the safe and efficient recovery of coal pillars in fractured areas through fault grouting modification. Simultaneously, as... Figure 3 As shown in the figure, the layout of the modified working face machine roadway 5, the modified working face ventilation roadway 6, and the modified longwall mining face 12 is as shown in the figure.

[0030] Regarding the coal pillar recovery method based on fault grouting modification disclosed in this invention, combined with Figure 2 , Figure 3 As shown, the specific processing steps include the following:

[0031] Step 1: Calculate the width of the fault-resistant water-blocking coal (rock) pillar according to current national regulations, and excavate a grouting tunnel beyond the width of the water-blocking coal (rock) pillar based on the calculation results;

[0032] Based on the exploration of the fault's water conductivity through drilling and geophysical surveys, and in conjunction with the stratigraphic relationships between the coal seam, fault, and aquifer, the influence range of the fault is calculated in accordance with current national regulations.

[0033] Step 2: Determine the grouting radius and obtain the spacing between each drilling site segment based on the grouting radius;

[0034] By planning the working face, the grouting radius is determined on the basis of ensuring that the grouting changes the rock mass and enables safe mining. The spacing between each drilling site segment is then calculated from the grouting radius. The calculation of the spacing between drilling site segments is an existing technology and will not be elaborated here.

[0035] Step 3: Arrange drilling sites in sections within the grouting tunnel, with each drilling site containing grouting boreholes for grouting reinforcement;

[0036] The grouting boreholes are directional inclined holes to reinforce the fault. At the same time, the pre-grouting exploration holes, grouting holes, and post-grouting inspection holes should be reasonably allocated. The final position of the grouting hole should reach the fault position and ensure that the grout diffusion range completely covers the fault fracture zone.

[0037] Step 4: High-pressure injection of grout through grouting boreholes to reinforce the fractured rock mass in the fault area;

[0038] The grout used is prepared in advance according to the design parameters based on specific needs. The grout is injected into the fault fracture zone and the area near the fault aquifer through grouting boreholes to reinforce the fractured rock mass in the fault area, thereby destroying the condition of the fault as a water-conducting channel.

[0039] Step 5: Inspect the grouting effect and determine whether the grouting effect meets the conditions for safe production at the working face;

[0040] The effectiveness of grouting modification can be verified through methods such as PQt curve analysis, core sampling through inspection holes, and geophysical exploration. This ensures that areas with structural damage are transformed into areas with intact and undamaged waterproof layers. After a comprehensive evaluation of the grouting effect, it can be determined whether the conditions for safe production at the working face are met.

[0041] Step Six: After confirming that the conditions for safe production at the working face are met, proceed with the working face layout. The working face layout is as follows: Figure 2 and Figure 3 As shown, the design involves arranging mining roadways adjacent to faults or leaving small coal pillars to achieve the recovery of water-proof coal pillars from faults.

[0042] Therefore, the coal pillar recovery method based on fault grouting modification disclosed in this invention targets the fault fracture zone and a portion of the aquifer near the fault, aiming to unlock the water-resistant coal pillar resources. After fault grouting modification using the method of this invention, the fault-damaged area can be transformed into an area with intact, undamaged aquifers, thus reducing or eliminating the fault coal pillar and enabling its recovery. This invention provides crucial technical support for the green, safe, and efficient mining of coal resources in structurally damaged areas, enabling the exploitation and utilization of fault coal pillar resources. It also extends the service life of mines, eases mine succession, and yields substantial economic and social benefits.

[0043] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present invention are also within the protection scope of the present invention.

Claims

1. A method for coal pillar recovery based on fault grouting modification, characterized in that: Includes the following steps: By arranging grouting tunnels, grouting modifications were carried out in parts of the fault fracture zone and the aquifer near the fault. After grouting modification, the conditions for the aquifer to damage the roadway and working face along the water-filling channel are restricted, and the structurally damaged area is transformed into a structurally damaged area with an intact aquitard and no fractures. Design mining roadway layouts that are close to faults or leave small coal pillars to enable the recovery of water-proof coal pillars in faults; Grouting modification includes the following steps: Step 1: Calculate the influence range of the fault, and based on the calculation results, excavate a grouting tunnel outside the influence range of the fault; Step 2: Determine the grouting radius and obtain the spacing between each drilling site segment based on the grouting radius; Step 3: Arrange drilling sites in sections within the grouting tunnel, and arrange grouting boreholes for grouting reinforcement in each drilling site; Step 4: High-pressure injection of grout into the fault fracture zone and the fracture zone of the aquifer near the fault through grouting boreholes to consolidate the fractured rock mass in the fault area.

2. The coal pillar recovery method based on fault grouting modification according to claim 1, characterized in that: Based on the exploration of the fault's water conductivity through drilling and geophysical surveys, and in conjunction with the stratigraphic relationships between the coal seam, fault, and aquifer, the range of the fault's influence is calculated.

3. The coal pillar recovery method based on fault grouting modification according to claim 1, characterized in that: By planning the working face, the grouting radius is determined on the basis of ensuring that grouting can change the rock mass and enable safe mining. The spacing between each drilling section is then calculated based on the grouting radius.

4. The coal pillar recovery method based on fault grouting modification according to claim 1, characterized in that: The grouting boreholes are arranged as directional inclined holes to reinforce the fault with grout; the final position of the grouting hole must reach the fault position and ensure that the grout diffusion range completely covers the fault fracture zone.

5. The coal pillar recovery method based on fault grouting modification according to any one of claims 1-4, characterized in that: After grouting modification, the grouting effect is inspected to determine whether the grouting effect meets the conditions for safe production at the working face. After confirming that the conditions for safe production at the working face are met, mining roadways are arranged adjacent to faults or with small coal pillars to realize the recovery of water-proof coal pillars in faults.

6. The coal pillar recovery method based on fault grouting modification according to claim 5, characterized in that: The evaluation methods used for grouting modification effects include PQt curve analysis, core sampling through inspection holes, and geophysical exploration.

Images