Refined segmented grouting method for goaf

Abstract

The invention relates to the technical field of goaf grouting, in particular to a goaf refined segmented grouting method which comprises the following steps: constructing exploration coring drilling on the earth surface above a goaf to obtain the corresponding relation between the stratum lithology and the thickness of the goaf; the to-be-filled area is divided into a caving accumulation area, a pure goaf area, a roof contact area and a bedrock fracture area from bottom to top, and the roof thickness of each grouting hole and the height of different areas are recorded; the method has the beneficial effects that the goaf is divided into a caving accumulation area, a pure goaf area, a roof contact area and a bedrock fracture area from bottom to top according to a goaf drilling exploration result; on the basis of fully considering the grouting effect and the grouting cost, a 110 mm main grouting pipe and a 25 mm grouting floral pipe are buried, pure goaf non-pressure filling, roof-contacted area non-pressure grouting, high-pressure splitting grouting and bedrock fracture area under-pressure filling are implemented in sequence, and cooperative control over the goaf grouting effect and the grouting cost is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of goaf grouting, in particular to a refined segmented grouting method for goaf. Background Art

[0002] Goaf grouting involves injecting prepared grouting materials into underground goafs through grouting channels. This forms a cemented mass that supports overlying strata, reduces rock movement, controls ground subsidence, and protects surface structures. It also seals groundwater channels, preventing and controlling water hazards associated with underground engineering construction.

[0003] Currently, goaf grouting primarily utilizes the full-hole filling method. This involves grouting holes throughout the entire area to be grouted. The grouting area is initially filled by pressureless gravity, achieving the initial filling of the goaf. The area to be grouted is then sealed with a grout stopper, and additional grouting is performed using pressurized grouting until the grouting volume and final pressure meet the design requirements. However, the interiors of goafs formed after mineral resource mining are extremely complex. The full-hole filling method does not fully consider the zoning characteristics of the area to be filled. Furthermore, the grouting material is relatively simple, mostly consisting of one of the conventional slurries, such as cement slurry, cement mortar, or concrete. While filling with cement slurry alone yields good results, the cost is high. While filling with concrete alone reduces the cost, the filling effect is unsatisfactory in some areas, such as caving accumulation areas and bedrock fissures. Therefore, current goaf grouting methods fail to achieve a coordinated control of grouting effectiveness and costs. Based on this, a refined segmented grouting method for goaf areas is proposed. On the basis of dividing the goaf areas into regions, different grouting schemes are formulated for different areas to achieve coordinated control of the grouting effect and grouting cost of the goaf areas. Summary of the Invention

[0004] The purpose of the present invention is to provide a refined segmented grouting method for goaf areas to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a method for refined segmented grouting in goafs, comprising the following steps: constructing exploration and coring drilling holes on the surface above the goaf to obtain the correspondence between the lithology and thickness of the goaf strata; dividing the area to be filled from bottom to top into a caving accumulation area, a pure void area, a roof connection area and a bedrock fissure area, and recording the roof thickness of each grouting hole and the height of different areas.

[0006] Preferably, it also includes: enlarging the exploration core drilling hole to serve as a grouting hole, the opening diameter of the grouting hole is 273mm, and after drilling to 2-5m of complete bedrock, installing a wall protection pipe with a diameter of 273mm and slightly above the ground surface for wall protection; then reducing the borehole diameter to 245mm, and drilling to the top of the caving accumulation area; starting from the top of the caving accumulation area, using a 273mm eccentric drill bit to drill with a follower pipe with a diameter of 245mm, drilling to 1-2m of the bottom plate of the goaf, withdrawing the drill bit, and leaving the follower pipe in the borehole with the top slightly higher than the lower end of the goaf roof; the entire follower pipe is connected in sections through threads, and the top is reversed.

[0007] Preferably, it also includes: lowering a 25mm diameter grouting flower pipe along the heel pipe wall to the bottom of the drill hole, the lateral slurry outlet range of the flower pipe covers the top connection area, the pure empty area, the falling accumulation area and 1-2m below the falling accumulation area, and the top of the flower pipe is slightly lower than the hole mouth; the flower pipe is divided into two parts, the upper part is steel, and the lower part is plastic, and the connecting head is located 3-5m above the top connection area; the early 25mm grouting flower pipe does not participate in grouting, its outer wall is wrapped with plastic wrap, and the top of the flower pipe is blocked with a rubber plug.

[0008] Preferably, the method further comprises: connecting the follower pipe to the drill rod through a reverse thread, and pulling out the follower pipe in sections; after the follower pipe is pulled out, pulling out the rubber plug on the top of the flower pipe, and connecting the top of the flower pipe to the grouting pump through a ground slurry pipeline.

[0009] Preferably, 5. The method for fine segmented grouting in a goaf according to claim 4, further comprising: lowering a 110 mm main grouting pipe to the top of the caving accumulation area, and connecting the top end of the grouting pipe to a grouting pump via a ground grouting pipeline.

[0010] Preferably, it also includes: pressureless filling of pure empty areas: using a grouting pump to pass C25 concrete slurry through a 110mm grouting pipe to fill the pure empty areas from bottom to top, stopping when the slurry surface reaches the bottom of the top connection area, and lifting the 110mm grouting pipe to the top connection area.

[0011] Preferably, it also includes: pressure-free grouting of the top connection area: after the pure empty area is filled for 12 hours, use a grouting pump to pour M15 cement mortar through a 110mm grouting pipe into the top connection area without pressure, and stop when the slurry surface reaches 3-5m above the top connection area, and lift out the 110mm grouting pipe.

[0012] Preferably, it also includes: high-pressure splitting grouting: after the top area is grouted for 48 hours, a grouting pump is used to pass M10 cement slurry through a pre-buried 25mm grouting flower tube to perform high-pressure splitting grouting on the gaps in the falling accumulation area, the gaps formed by the shrinkage of M15 cement mortar and C25 concrete after solidification, and the grouting volume and the end pressure meet the design requirements. After the grouting is completed, the upper half of the 25mm grouting flower tube - the steel pipe, is recycled, and the lower half - the plastic pipe is not recycled.

[0013] Preferably, it also includes: pressurized filling of bedrock fissure areas: placing a 50mm grouting pipe with a grouting plug into the grouting hole, with the grouting plug located 3-5m below the variable diameter area, and the slurry outlet slightly extending out of the grouting plug; using a grouting pump to pass M10 cement slurry through a 50mm grouting pipe to fill the bedrock fissure area, and stop when the grouting volume and the end pressure reach the design requirements, and recover the grouting pipe and the grouting plug after the slurry solidifies.

[0014] Preferably, the method further includes: sealing the hole: taking the wall protection pipe out of the grouting hole, and injecting M10 cement slurry into the bottom of the hole through a grouting pump until the cement slurry overflows from the hole mouth.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The proposed refined segmented grouting method for goaf areas divides the goaf into a caving accumulation zone, a pure goaf zone, a roof-joining zone, and a bedrock fissure zone, based on the results of goaf drilling exploration. Taking both grouting effectiveness and costs into account, the method employs the use of 110mm main grouting pipes and 25mm grouting tubes. Pressureless filling of the pure goaf zone, pressureless injection of the roof-joining zone, high-pressure splitting grouting, and pressurized filling of the bedrock fissure zone are sequentially implemented, achieving coordinated control of grouting effectiveness and costs in the goaf area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the drilling shape, wall protection tube and casing position of the present invention; Figure 2 This is a schematic diagram of a preset 25mm plastic grouting flower tube in the present invention; Figure 3 This is a schematic diagram of the position of the grouting pipe of the present invention; Figure 4 This is a schematic diagram of pure void grouting in the present invention; Figure 5 This is a schematic diagram of grouting in the top joint area of the present invention; Figure 6 This is a schematic diagram of high-pressure splitting grouting according to the present invention; Figure 7 This is a schematic diagram of the pressure filling of the bedrock fracture zone of the present invention; Figure 8 This is a schematic top view of the drilling and grouting pipe of the present invention; Figure 9 This is the grouting flow chart of the present invention. DETAILED DESCRIPTION

[0017] In order to clearly and completely describe the objectives and technical solutions of the present invention and make the advantages more clearly understood, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, not all of them, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] See also Figures 1 to 9 The present invention provides a technical solution: a method for fine segmented grouting in goaf, comprising the following steps: (1) Conduct exploration and core drilling on the surface above the goaf to obtain the lithology and thickness of the goaf. The area to be filled is divided from bottom to top into caving accumulation area, pure void area, roof connection area and bedrock fissure area, and the roof thickness of each grouting hole and the height of different areas are recorded.

[0019] (2) The exploration core drill hole is enlarged and used as a grouting hole. The opening diameter of the grouting hole is 273mm. After drilling to 2-5m of intact bedrock, a 273mm diameter wall protection pipe is installed to protect the wall. The wall protection pipe should be slightly higher than the ground surface. The borehole is then reduced to 245mm in diameter and drilled to the top of the caving accumulation area. Starting from the top of the caving accumulation area, follow-up drilling is carried out using a pipe until 1-2m below the bottom plate of the goaf. The drill bit is withdrawn and the pipe is left in the borehole. The top of the pipe should be slightly higher than the bottom of the goaf roof. The drill bit used for follow-up drilling is a 273mm eccentric drill bit with a pipe diameter of 245mm. The entire pipe is connected in sections by threads, and the top of the pipe is treated with reverse threading to facilitate the subsequent extraction of the borehole after connecting it to the drill pipe.

[0020] (3) Lower the 25mm diameter grouting tube along the wall of the heel pipe to the bottom of the borehole. The lateral grouting hole of the tube should cover the top connection area, the pure empty area, the caving accumulation area, and 1-2m below the caving accumulation area. The top of the tube should be slightly lower than the hole mouth. The tube is divided into two parts: the upper part of the tube is made of steel and the lower part is made of plastic. The connection between the upper and lower parts is located 3-5m above the top connection area. Since the 25mm grouting tube does not participate in the grouting in the early stage, the outer wall of the 25mm grouting tube needs to be wrapped with plastic wrap to prevent the slurry from flowing into the 25mm grouting tube and causing blockage when the main grouting tube is grouting. The top of the tube is blocked with a rubber plug to prevent foreign matter from falling into the tube when the heel pipe is lifted out.

[0021] (4) Connect the follower pipe to the drill pipe through the reverse thread and pull out the follower pipe in sections. After the follower pipe is pulled out, pull out the rubber plug on the top of the flower pipe and connect the top of the flower pipe to the grouting pump through the ground grouting pipeline.

[0022] (5) Lower the 110mm main grouting pipe to the top of the caving accumulation area, and connect the top of the grouting pipe to the grouting pump through the ground grouting pipeline.

[0023] (6) Pressureless filling of pure void area: Use a grouting pump to pump C25 concrete slurry through a 110mm grouting pipe to fill the pure void area from bottom to top. Stop when the slurry level reaches the bottom of the top connection area. Lift the 110mm grouting pipe to the top connection area.

[0024] (7) Pressureless grouting of the joint area: After the pure empty area has been filled for 12 hours, use a grouting pump to pour M15 cement mortar through a 110mm grouting pipe into the joint area without pressure. Stop when the slurry surface reaches 3 to 5 meters above the joint area, and then pull out the 110mm grouting pipe.

[0025] (8) High-pressure splitting grouting: After 48 hours of grouting in the joint area, use a grouting pump to inject M10 cement slurry through the pre-buried 25mm grouting tube to perform high-pressure splitting grouting in the gaps in the caving accumulation area and the gaps formed by the shrinkage of M15 cement mortar and C25 concrete after solidification. Stop when the grouting volume and final pressure meet the design requirements. After the grouting is completed, the upper half (steel pipe) of the 25mm grouting tube is recycled, while the lower half (plastic pipe) is not recycled.

[0026] (9) Filling the bedrock fissures under pressure: Place a 50mm grouting pipe with a grout stopper into the grouting hole. The grout stopper should be located 3-5m below the diameter change zone, and the grout outlet should extend slightly beyond the grout stopper. Use a grouting pump to pump M10 cement slurry through the 50mm grouting pipe to fill the bedrock fissures. Stop grouting when the grouting volume and final pressure meet the design requirements. After the grouting solidifies, reclaim the grouting pipe and grout stopper.

[0027] (10) Sealing the hole: Take out the wall protection pipe from the grouting hole and inject M10 cement slurry into the bottom of the hole through the grouting pump until the cement slurry overflows from the hole mouth.

[0028] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A refined segmented grouting method for goaf, characterized by: The following steps are involved: Core drilling is carried out on the surface above the goaf to obtain the correspondence between the lithology and thickness of the goaf; the area to be filled is divided from bottom to top into the caving accumulation area, pure void area, roof connection area and bedrock fissure area, and the roof thickness of each grouting hole and the height of different areas are recorded.

2. A method for fine segmented grouting in goaf according to claim 1, characterized in that: Also includes: The exploration core drilling hole is enlarged to serve as a grouting hole with an opening diameter of 273mm. After drilling to 2-5m of intact bedrock, a wall protection pipe with a diameter of 273mm and slightly above the ground is installed for wall protection; the borehole is then reduced in diameter to 245mm and drilled to the top of the caving accumulation area; starting from the top of the caving accumulation area, a 273mm eccentric drill bit with a follower pipe of 245mm is used for drilling, and the follower pipe is drilled to 1-2m of the bottom plate of the goaf. The drill bit is withdrawn, and the follower pipe is left in the borehole with the top slightly higher than the lower end of the goaf roof; the entire follower pipe is connected in sections through threads, and the top is reversed.

3. A method for fine segmented grouting in goaf according to claim 2, characterized in that: Also includes: A 25mm diameter grouting flower pipe is lowered along the pipe wall to the bottom of the drill hole. The lateral slurry outlet range of the flower pipe covers the top connection area, pure empty area, caving accumulation area and 1-2m below the caving accumulation area. The top of the flower pipe is slightly lower than the hole mouth. The flower pipe is divided into two parts, the upper part is steel and the lower part is plastic. The connection head is located 3-5m above the top connection area. The early 25mm grouting flower pipe does not participate in the grouting. Its outer wall is wrapped with plastic wrap, and the top of the flower pipe is blocked with a rubber plug.

4. A method for fine segmented grouting in goaf according to claim 3, characterized in that: Also includes: Connect the follower pipe to the drill pipe through reverse thread and pull out the follower pipe in sections; After the follower pipe is brought out, pull out the rubber plug on the top of the flower pipe, and the top of the flower pipe is connected to the grouting pump through the ground slurry pipeline.

5. A method for fine segmented grouting in goaf according to claim 4, characterized in that: Also includes: The 110mm main grouting pipe is lowered to the top of the caving accumulation area, and the top of the grouting pipe is connected to the grouting pump through the ground grouting pipeline.

6. A method for fine segmented grouting in goaf according to claim 5, characterized in that: Also includes: Pressureless filling of pure void areas: Use a grouting pump to pass C25 concrete slurry through a 110mm grouting pipe to fill the pure void area from bottom to top. Stop when the slurry surface reaches the bottom of the top connection area, and lift the 110mm grouting pipe to the top connection area.

7. A method for fine segmented grouting in goaf according to claim 6, characterized in that: Also includes: Pressure-free grouting of the joint area: After the pure empty area is filled for 12 hours, use a grouting pump to pour M15 cement mortar through a 110mm grouting pipe into the joint area without pressure. Stop when the slurry surface reaches 3-5m above the joint area, and lift out the 110mm grouting pipe.

8. The method for fine segmented grouting in goaf according to claim 7, characterized in that: Also includes: High-pressure splitting grouting: After 48 hours of grouting in the joint area, use a grouting pump to pump M10 cement slurry through the pre-buried 25mm grouting flower tube to perform high-pressure splitting grouting on the gaps in the falling accumulation area, the gaps formed by the shrinkage of M15 cement mortar and C25 concrete after solidification. Stop when the grouting volume and the end pressure meet the design requirements; after the grouting is completed, the upper half of the 25mm grouting flower tube - the steel pipe, and the lower half - the plastic pipe will not be recycled.

9. A method for fine segmented grouting in goaf according to claim 8, characterized in that: Also includes: Filling the bedrock fissure area under pressure: Place a 50mm grouting pipe with a grouting plug into the grouting hole. The grouting plug should be located 3-5m below the variable diameter area, and the slurry outlet should extend slightly beyond the grouting plug. Use a grouting pump to pass M10 cement slurry through the 50mm grouting pipe to fill the bedrock fissure area. Stop grouting when the grouting volume and final pressure reach the design requirements. Recover the grouting pipe and grouting plug after the slurry solidifies.

10. A method for fine segmented grouting in goaf according to claim 9, characterized in that: Also includes: Sealing the hole: Take out the wall protection pipe from the grouting hole and inject M10 cement slurry into the bottom of the hole through the grouting pump until the cement slurry overflows from the hole mouth.

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