Open pit backfill reinforcement device and method

Abstract

The present invention aims to provide an open pit backfill reinforcement device and reinforcement method to solve the problems of uneven and insufficient slurry diffusion in the existing conventional grouting method, and complex pipe body production, multiple construction steps, long construction time, and poor anchoring effect in the sleeve valve pipe grouting method.

Description

Technical Field

[0001] The present invention belongs to the technical field of open-pit mine backfill slag reinforcement, and in particular relates to a device and method for reinforcing backfill material in an open-pit coal mine after mining. Background Art

[0002] After stripping, open-pit mines are backfilled. During backfilling, materials such as rocks, debris, and powder stripped from the top of the coal seam are added to the stripping pit. Depending on the coal seam's occurrence, the backfill in steeply inclined coal seams may overburden the underlying coal seam, hindering the normal excavation of the lower coal seam tunnels. To ensure smooth excavation of the lower coal seam tunnels, the conventional method is to reinforce the backfill with grouting. Grouting consolidates the backfill, improving its overall stability and preventing collapse and roof falls during tunneling beneath the backfill.

[0003] Currently, the two most commonly used grouting methods for consolidating slag backfill are conventional grouting and sleeve-valve-tube grouting. Conventional grouting involves grouting the bare hole section of the backfill layer directly after the borehole is installed and the orifice pipe is installed. With sleeve-valve-tube grouting, a guide pipe is first constructed in the formation, followed by the sleeve-valve pipe placed inside the guide pipe. The guide pipe is then removed, and casing material is injected, followed by grouting. The backfill in open pits is extremely uneven in size and poorly sorted. It contains large rocks exceeding 1 meter in diameter, small rocks tens of centimeters in diameter, crushed rocks several centimeters in diameter, as well as granular materials, rock dust, and soil. These various rocks, crushed rocks, particles, and powders are mixed and piled together, and the gaps between the rocks are filled with crushed rocks and powder, some densely and others loosely, forming a complex, highly heterogeneous, loose mixture. Consequently, conventional grouting methods suffer from the disadvantage that the slurry, under pressure, diffuses along the most favorable path of least resistance, making it difficult to achieve relatively uniform filling of the gaps both vertically and horizontally, effectively enveloping and cementing the injected backfill. Sleeve-valve tube grouting can achieve relatively uniform slurry diffusion and transport both vertically and horizontally throughout the borehole. However, sleeve-valve tubes require specialized fabrication, involve multiple construction steps and a long construction cycle. Consolidation of the backfill after grouting is still difficult, resulting in complex tube fabrication, multiple construction steps, long construction times, and poor anchoring effectiveness. Summary of the Invention

[0004] The present invention aims to provide an open pit backfill reinforcement device and method to solve the problems of uneven and insufficient slurry diffusion in the existing conventional grouting method, and the problems of complex pipe body production, multiple construction steps, long construction time, and poor anchoring effect in the sleeve valve pipe grouting method.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] A device for reinforcing backfill in an open pit comprises a grouting solid pipe, a slit-type grouting flower pipe connected to one end of the grouting solid pipe, the inner side of one end of the slit-type grouting flower pipe being connected to a follow-pipe drilling tool, and air follow-pipe drilling being used to drill the slit-type grouting flower pipe to a certain depth in the original stratum of the open pit, and slurry being injected into the stratum through the slits on the slit-type grouting flower pipe to achieve grouting reinforcement of the backfill.

[0007] The present invention also has the following technical features:

[0008] A coaxial inner tube is also provided inside the grouting solid tube and the slit-type grouting flower tube. The inner tube is connected to the anti-impact pad, the anti-impact pad is fixedly connected to the follow-pipe drill bit, the outer surface of the anti-impact pad is fitted and slidably connected to the inner wall of the slit-type grouting flower tube, and the upper edge of the anti-impact pad is sealed with the outer edge of the inner tube end face, which is used to discharge dust and slag particles along the hollow of the inner tube under the action of aerodynamics.

[0009] Furthermore, the anti-collision pad is provided with slag discharge ports distributed along the radial direction.

[0010] The pipe drill tool of the present invention comprises at least a center drill bit, an eccentric drill bit, a guide, a pipe shoe, and an impactor, wherein an eccentric drill bit is provided at one end of the center drill bit, a guide is provided on the eccentric drill bit, the guide is connected to the impactor, the pipe shoe is fixed on the inner side of the end of the slit-type floral pipe, and the guide is connected to the slit-type grouting floral pipe through the pipe shoe.

[0011] Another transformable structure that can be realized by the follow-up tube drill tool of the present invention can also be that the follow-up tube drill tool at least includes a center drill bit, an eccentric drill bit, a guide, a pipe shoe, and an impactor, wherein an eccentric drill bit is provided at one end of the center drill bit, a guide is provided on the eccentric drill bit, the guide is connected to the impactor, and the pipe shoe is fixedly connected to the slit-type grouting flower pipe; the other end of the guide is fixedly connected to the inner tube through an anti-collision pad; the upper edge of the anti-collision pad is sealedly connected to the outer edge of the end face of the inner tube, the lower edge of the anti-collision pad is fixedly connected to the upper end face of the guide, and the impactor axially penetrates the anti-collision pad and the center of the inner tube.

[0012] The inner tube of the present invention is preferably made of a lightweight resin material.

[0013] At the same time, the present invention also discloses a method for reinforcing backfill in an open pit, comprising the following steps:

[0014] Step 1: Arrange grouting holes;

[0015] Step 2: Processing slit-type grouting flower pipes and grouting solid pipes;

[0016] Step 3: Using the air-follow-pipe drilling process, vertically drill the slotted grouting pipe and the connected grouting pipe into the backfill of the open-pit pit one by one at the grouting hole position, and drill the slotted grouting pipe and the pipe to a certain depth in the original formation;

[0017] Step 4: The eccentric drill bit retracts, and the guide drives the eccentric drill bit and the center drill bit to be taken out of the slit grouting pipe and the grouting pipe in turn, and the inner wall of the grouting pipe is washed by the air compressor;

[0018] Step 5: Grouting the backfill layer, injecting slurry into the stratum through the slits on the slit grouting pipe until the grouting end standard is reached, completing the single-hole grouting at the grouting hole position;

[0019] Step 6: Repeat steps 2 to 5, and carry out pipe drilling and grouting at other grouting holes until the drilling and grouting of all grouting holes are completed, and the open pit backfill reinforcement project is completed.

[0020] Due to the difference in the structure of the reinforcement device, another open pit backfill reinforcement method of the present invention includes the following steps:

[0021] Step 1: Arrange grouting holes;

[0022] Step 2: Processing slit-type grouting flower pipes, grouting solid pipes, inner pipes, and anti-collision pads;

[0023] Step 3: Using the air-following pipe drilling process, the slotted grouting flower pipe, the grouting solid pipe connected to it, and the inner pipe arranged inside the grouting flower pipe and the grouting solid pipe are drilled vertically into the backfill of the open-pit mining pit one by one at the grouting hole position, and the slotted grouting flower pipe and the pipe are drilled to a certain depth in the original formation;

[0024] Step 4: The eccentric drill bit retracts, and the guide drives the eccentric drill bit, center drill bit, anti-collision pad and inner tube to be taken out from the slit grouting pipe and grouting solid pipe in turn, and the inner wall of the grouting pipe is washed by using an air compressor;

[0025] Step 5: Grouting the backfill layer, injecting slurry into the stratum through the slits on the slit grouting pipe until the grouting end standard is reached, completing the single-hole grouting at the grouting hole position;

[0026] Step 6: Repeat steps 2 to 5, and carry out pipe drilling and grouting at other grouting holes until the drilling and grouting of all grouting holes are completed, and the open pit backfill reinforcement project is completed.

[0027] In particular, the step 1 of arranging the grouting holes is to select a range on the backfill above the tunnel and arrange the grouting holes according to the set shape and spacing.

[0028] Furthermore, in the step 2, processing the slit-type grouting flower pipe, the slits are constructed along the axis of the pipe on different cross sections, wherein the slits on adjacent cross sections are arranged in a staggered manner.

[0029] As a whole, the present invention has the technical effects of different reinforcement mechanism, simple pipe body production, fewer construction steps, fast construction speed, good anchoring effect, etc. compared with the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of grouting reinforcement of a single grouting hole in the reinforcement method of the present invention.

[0031] Figure 2 This is a schematic diagram of the first structure of the pit backfill reinforcement device of the present invention.

[0032] Figure 3 This is a schematic diagram of the second structure of the pit backfill reinforcement device of the present invention.

[0033] Figure 4 This is a schematic diagram of the three-dimensional structure of the second pit backfill reinforcement device of the present invention.

[0034] FIG5 is a schematic diagram of the structure of the anti-collision pad in the second pit backfill reinforcement device of the present invention, wherein Figure 5a This is a top view of the impact pad. Figure 5b This is the cross-sectional view of the anti-collision pad in the AA direction. Figure 5c For anti-collision pad Figure 5a Top view when turning 45°, Figure 5d for Figure 5c BB direction cross-section.

[0035] The symbols in the figure represent the following meanings:

[0036] 1. Grouting flower pipe, 2. Grouting solid pipe, 3. Slit, 4. Solid pipe opening, 5. Backfill layer, 6. Coal seam; 7. Groundwater level, 8. Center drill bit, 9. Eccentric drill bit, 10. Guide, 11. Pipe shoe, 12. Impactor, 13. Anti-impact pad, 14. Inner pipe, 15. Slag outlet.

[0037] The specific contents of the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0038] 1. Differences between the present invention and the prior art in terms of design principles and technical effects

[0039] 1. Different reinforcement mechanisms

[0040] The reinforcement mechanism of conventional grouting and sleeve valve tube grouting is that the slurry fills the voids and wraps the grouting body, and the dispersed materials in the grouting area are consolidated together through the bonding effect of the cement slurry after solidification. The difference between the two is that the filling and wrapping effect of the conventional grouting method is not as good as the sleeve valve tube grouting method. In addition, the sleeve valve tube left in the hole after grouting can play a certain role in anchoring the rebar. In addition to the slurry filling the voids, wrapping the grouting body, and anchoring the rebar, the reinforcement mechanism of the present invention is more importantly to play the role of "tree root anchoring". Each grouting pipe is like an "anchor rod" dropped from the sky. The slurry injected from the cuts at different depths and directions is like a burr-shaped tree root, which can organically combine the grouting pipe and the slag body, greatly improving the integrity and stability of the open pit backfill, and improving both the ability of the backfill to resist sinking and deformation and the ability of the backfill to resist lateral deformation. Although the sleeve valve tube has a certain effect of planting reinforcement, the one-way expansion rubber ring on the sleeve valve tube will rebound and shrink and stick to the grouting pipe after the grouting stops, so it belongs to the "single reinforcement" type anchoring. The present invention belongs to the "single reinforcement + multi-dimensional burrs" type tree root anchoring. Obviously, the reinforcement mechanism of "single reinforcement" is not as good as "single reinforcement + multi-dimensional burrs".

[0041] 2. Process differences

[0042] Compared with sleeve valve pipe grouting, the invention has the advantages of simple pipe body manufacturing, fewer construction steps and faster construction speed.

[0043] 1) The sleeve valve tube is a double-tube structure, specifically including a grouting pipe, an expansion ring, an inner tube, a connector, a grouting ring, etc., and its manufacturing process is complicated. Although the present invention also has a double tube, the outer tube is only a layer of metal tube. It only needs to cut the seam in the tube to complete the processing of the tube. The tube body is very simple to make, and there is a wide range of choices for the inner tube. Light resin pipes or modified resin pipes are preferred, and metal pipes can also be used.

[0044] 2) The sleeve valve pipe grouting method requires first constructing a guide tube, then lowering the sleeve valve pipe, then pouring the casing material, and then withdrawing the guide tube before grouting can begin. The present invention uses a grouting flower pipe and grouting solid pipe, and after the follow-up drill and inner pipe are drilled into place, the well is washed and grouting can begin. The entire method has fewer construction steps.

[0045] 3) The sleeve valve pipe grouting method has a slow construction speed in actual engineering due to the complex pipe manufacturing and many construction steps. The pipe manufacturing of the present invention is simple. After the manufacturing is completed, the pipes (inner and outer pipes) are drilled into the backfill layer at one time, and then the pipe drilling tool is taken out to directly carry out grouting. The construction links are few, the speed is fast and the construction period is short.

[0046] 3. Difference in anchoring effect

[0047] After the sleeve valve tube grouting method is completed, the sleeve valve tube itself in the formation also has a certain anchoring effect, but the anchoring effect is limited and is far less effective than the "tree root type" anchoring effect of the present invention:

[0048] 1) After the sleeve valve tube grouting is completed, the expansion ring shrinks, and the slurry outside the tube is isolated from the slurry inside the tube. After the grouting of the present invention is completed, the slurries inside and outside the tube are still connected to each other, and a root-like anchor body can be formed from the inside to the outside.

[0049] 2) The grouting port of the sleeve valve tube is in a horizontal multi-point shape, while the grouting port of the present invention is in a multi-directional long strip shape with a large cutting width, so the volume of the tree root-like slurry is large and the roots are dense and burrs are dense.

[0050] 3) The spacing between the grouting ports of the sleeve valve pipe is large, generally up to 50 cm, while the spacing between the slits of each layer of the present invention is small, which can be less than 10 cm, so the density of the slurry anchor body outside the grouting pipe is large.

[0051] 4) The sleeve valve pipe has a small diameter and thin wall. The pipe diameter / wall thickness generally does not exceed 100mm / 6mm, and most of the materials are PVC. The pipe diameter and wall thickness of the present invention can exceed 300mm / 10mm, and the material is a metal pipe. As an "anchor rod" for anchoring the stratum, its diameter is thick and the wall is thick.

[0052] In summary, the present invention has a high density of slits in the same section, and a small spacing between slits in different sections. The material of the embedded steel bars is good, the pipe diameter is large, the pipe wall is thick, and there are many burrs. During grouting, there are many slurry outlets and the length of the slurry outlets is large. The slurry inside and outside the pipe is connected as a whole, which can fully fill the various gaps in the backfill, forming a structure in which vertical large-diameter embedded steel bars, spatial network grouting bodies and backfill are integrated. The anchoring effect after the slurry solidifies far exceeds that of sleeve valve pipe grouting.

[0053] 4. The outer pipe is cut without air leakage and the drilling efficiency is high.

[0054] Although there are slits on the grouting outer tube of the present invention, since the inner tube is arranged inside the slit-type grouting flower tube and the grouting solid tube, air leakage from the slits of the outer tube is not likely to occur during air drilling, and the drilling efficiency is high.

[0055] 2. Specific technical solutions of the present invention

[0056] Based on the above technical concept and principle, see Figure 1-Figure 2 The present invention discloses a device for reinforcing backfill in an open pit, comprising a grouting solid pipe 2, one end of which is connected to a slit-type grouting flower pipe 1, the inner side of one end of which is connected to a follow-up drill tool, and air follow-up drilling is adopted to drill the slit-type grouting flower pipe 1 to a certain depth in the original stratum of the open pit, and slurry is injected into the stratum through the slits 3 on the slit-type grouting flower pipe 2 to achieve reinforcement of the backfill.

[0057] In order to improve the drilling efficiency and ensure that there is no leakage of the outer pipe during the air-follow-pipe drilling process, the present invention also provides another open pit backfill reinforcement device, see Figure 3 、 Figure 4The specific structure is as follows: an open pit backfill reinforcement device, including a grouting solid pipe 2, a slit grouting flower pipe 1 is connected to one end of the grouting solid pipe 2, and an inner pipe 14 is also provided inside the grouting solid pipe 2 and the slit grouting flower pipe 1.

[0058] The inner tube 14 can be made of a lightweight resin material. This ensures that the outer tube, i.e., the slotted grouting tube 1, maintains good airtightness during air-casing drilling. This allows dust and slag particles generated during drilling to be discharged along the inner wall of the inner tube 14, thereby effectively improving the efficiency of the air-casing drilling process. Furthermore, the choice of a lightweight resin material helps to cushion the collision forces between the inner tubes during bottom drilling with an eccentric drill bit and simultaneous casing follow-up, thereby improving the overall stability of the entire device.

[0059] The inner tube 14 is fixedly connected to the follow-up drill bit through the anti-collision pad 13. The outer surface of the anti-collision pad 13 is slidingly connected to the inner wall of the slit-type grouting flower tube 1. The upper edge of the anti-collision pad 13 is tightly connected to the outer edge of the end face of the inner tube 14. The anti-collision pad 13 is also provided with slag discharge holes 15 distributed along the diameter, which are used to discharge dust and slag particles along the inner tube wall of the inner tube 14 under the action of aerodynamics.

[0060] Referring to Figure 5 , the design of the present invention's impact pad 13 serves to cushion the vibration stresses of the guide 10 and inner tube 14 during air drilling. Furthermore, the structure of the impact pad 13, while maintaining a connection with the inner tube 14, further provides a closed seal, preventing dust and slag particles from escaping into the slit-type grouting pipe 1 and through the slits 3 , thereby improving the airtightness of the entire air drilling process. The impact pad 13 shown in Figure 5 is only one structural form; any technical solution that can achieve the same effect is within the scope of protection of this invention.

[0061] Through air drilling, the slit grouting pipe 1 is drilled into the original stratum of the open pit to a certain depth, and slurry is injected into the stratum through the slits 3 on the slit grouting pipe 2 to reinforce the backfill.

[0062] It should be noted that the air follow-up drill tools used in the air follow-up drill process of the present invention all use existing follow-up drill tool structures, that is, to assist in achieving bottom expansion drilling and synchronous follow-up casing wall protection. The follow-up drill tool at least includes a center drill bit 8, an eccentric drill bit 9, a guide 10, a pipe shoe 11, and an impactor 12. The present invention is an open pit backfill reinforcement device, and the connection relationship between the components of the follow-up drill tool is as follows: an eccentric drill bit 9 is provided at one end of the center drill bit 8, a guide 10 is provided on the eccentric drill bit 9, and the pipe shoe 11 is fixed on the inner side of the end of the slit-type flower pipe, and the guide 10 is connected to the slit-type grouting flower pipe 1 through the pipe shoe 11.

[0063] The specific structure of another open pit backfill reinforcement device of the present invention and the connection position relationship between the pipe drill are as follows: Figure 3 、 Figure 4 An eccentric drill bit 9 is provided at one end of the center drill bit 8, and a guide 10 is provided on the eccentric drill bit 9. The guide 10 is connected to the impactor 12, and the pipe shoe 11 connects the guide 10 to the slit-type grouting flower pipe 1; the other end of the guide 10 is connected to the inner tube 14 through an anti-collision pad 13; the upper edge of the anti-collision pad 13 is sealed with the outer edge of the end face of the inner tube 14, and the lower edge of the anti-collision pad 13 is fixedly connected to the upper end face of the guide 10, and the impactor 12 axially penetrates the center of the anti-collision pad 13 and the inner tube 14.

[0064] In combination with the two different reinforcement devices disclosed in the present invention, the methods for reinforcing the backfill of an open pit using the devices are as follows:

[0065] If you use Figure 2 The reinforcement device shown in FIG. 1 comprises the following steps:

[0066] Step 1: Arrange grouting holes;

[0067] Step 2: Processing slit-type grouting flower pipes and grouting solid pipes;

[0068] Step 3: Using the air-follow-pipe drilling process, vertically drill the slotted grouting pipe and the connected grouting pipe into the backfill of the open-pit pit one by one at the grouting hole position, and drill the slotted grouting pipe and the pipe to a certain depth in the original formation;

[0069] Step 4: The eccentric drill bit retracts, and the guide drives the eccentric drill bit and the center drill bit to be taken out of the slit grouting pipe and the grouting pipe in turn, and the inner wall of the grouting pipe is washed by the air compressor;

[0070] Step 5: Grouting the backfill layer, injecting slurry into the stratum through the slits on the slit grouting pipe until the grouting end standard is reached, completing the single-hole grouting at the grouting hole position;

[0071] Step 6: Repeat steps 2 to 5, and carry out pipe drilling and grouting at other grouting holes until the drilling and grouting of all grouting holes are completed, and the open pit backfill reinforcement project is completed.

[0072] If you use Figure 3 、 Figure 4 The reinforcement device shown in FIG. 1 comprises the following steps:

[0073] Step 1: Arrange grouting holes;

[0074] Step 2: Processing slit-type grouting flower pipes, grouting solid pipes, inner pipes, and anti-collision pads;

[0075] Step 3: Using the air-following pipe drilling process, the slotted grouting flower pipe, the grouting solid pipe connected to it, and the inner pipe arranged inside the grouting flower pipe and the grouting solid pipe are drilled vertically into the backfill of the open-pit mining pit one by one at the grouting hole position, and the slotted grouting flower pipe and the pipe are drilled to a certain depth in the original formation;

[0076] Step 4: The eccentric drill bit retracts, and the guide drives the eccentric drill bit, center drill bit, anti-collision pad, and inner tube to be taken out from the slit grouting pipe and grouting solid pipe in turn, and the inner wall of the grouting pipe is washed by using an air compressor;

[0077] Step 5: Grouting the backfill layer, injecting slurry into the stratum through the slits on the slit grouting pipe until the grouting end standard is reached, completing the single-hole grouting at the grouting hole position;

[0078] Step 6: Repeat steps 2 to 5, and carry out pipe drilling and grouting at other grouting holes until the drilling and grouting of all grouting holes are completed, and the open pit backfill reinforcement project is completed.

[0079] In both of the above solutions, step 1 involves arranging grouting holes. This involves selecting a range within the backfill above the roadway and arranging the holes in a predetermined shape and spacing. The grouting hole arrangement can be designed based on the working environment to fully utilize the working environment.

[0080] Step 2 in the above two schemes: processing the slit-type grouting flower tube 1; processing the slit-type grouting flower tube 1 is to construct longitudinal slits 3 along the axial direction of the pipe on different cross sections, wherein the slits 3 on adjacent cross sections are staggered.

[0081] The above is the technical solution of the present invention. Any equivalent replacement of the technical features of the present invention within the technical concept of this solution shall fall within the protection scope of the present invention.

Claims

1. An open pit backfill reinforcement device, comprising a grouting solid pipe (2), characterized in that: A slit-type grouting flower pipe (1) is connected to one end of the grouting solid pipe (2), wherein the slit-type grouting flower pipe (1) is constructed with longitudinal slits on different cross sections along the axial direction of the pipe, wherein the slits on adjacent cross sections are arranged in a staggered manner; An inner tube (14) is further provided inside the grouting solid tube (2) and the slit-type grouting flower tube (1), the inner tube (14) is connected to the anti-collision pad (13), the anti-collision pad (13) is fixedly connected to the pipe drilling tool, the outer surface of the anti-collision pad (13) is fitted and slidably connected to the inner wall of the slit-type grouting flower tube (1), the upper edge of the anti-collision pad (13) is sealedly connected to the outer edge of the end face of the inner tube (14), and is used to discharge dust and slag particles along the hollow of the inner tube (14) under the action of aerodynamic force, ensuring that no air leakage occurs from the outer tube slit during the air pipe drilling process, and the anti-collision pad (13) is provided with slag discharge ports (15) distributed along the radial direction; The inner side of one end of the slit-type grouting flower pipe (1) is connected to a follow-pipe drilling tool, and air follow-pipe drilling is used to drill the slit-type grouting flower pipe (1) to a certain depth of the original stratum of the open pit, and slurry is injected into the stratum through the slit (3) on the slit-type grouting flower pipe (1) to achieve reinforcement of the backfill.

2. The open pit backfill reinforcement device according to claim 1, characterized in that: The following pipe drilling tool at least comprises a center drill bit (8), an eccentric drill bit (9), a guide (10), a pipe shoe (11), and an impactor (12), wherein an eccentric drill bit (9) is provided at one end of the center drill bit (8), a guide (10) is provided on the eccentric drill bit (9), the guide (10) is connected to the impactor (12), and the pipe shoe (11) is fixedly connected to the slit-type grouting flower pipe (1); the other end of the guide (10) is fixedly connected to the inner pipe (14) through an anti-collision pad (13); the upper edge of the anti-collision pad (13) is sealedly connected to the outer edge of the end face of the inner pipe (14), the lower edge of the anti-collision pad (13) is fixedly connected to the upper end face of the guide (10), and the impactor (12) axially penetrates the anti-collision pad (13) and the center of the inner pipe (14).

3. The open pit backfill reinforcement device according to claim 2, characterized in that: The inner tube (14) is made of resin material.

4. A method for reinforcing open pit backfill using the reinforcement device according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Arrange grouting holes; Step 2: Processing slit-type grouting flower pipes, grouting solid pipes, inner pipes, and anti-collision pads; Step 3: Using the air-following pipe drilling process, the slotted grouting flower pipe, the grouting solid pipe connected to it, and the inner pipe arranged inside the grouting flower pipe and the grouting solid pipe are drilled vertically into the backfill of the open-pit mining pit one by one at the grouting hole position, and the slotted grouting flower pipe and the pipe are drilled to a certain depth in the original formation; Step 4: The guide drives the eccentric drill bit, center drill bit, anti-collision pad and inner tube to be taken out from the slit grouting pipe and grouting solid pipe in turn, and the inner wall of the grouting pipe is washed by the air compressor; Step 5: Grouting the backfill layer, injecting slurry into the stratum through the slits on the slit grouting pipe until the grouting end standard is reached, completing the single-hole grouting at the grouting hole position; Step 6: Repeat steps 2 to 5, and carry out pipe drilling and grouting at other grouting holes until the drilling and grouting of all grouting holes are completed, and the open pit backfill reinforcement project is completed.

5. The open pit backfill reinforcement method according to claim 4, characterized in that: The first step of arranging the grouting holes is to select a range of backfill materials above the roadway and arrange the grouting holes according to the set shape and spacing.

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