An active reinforcement process for hole wall when rotary drilling penetrates through permeable sand and pebble layer

Abstract

The application discloses an active reinforcement process for a hole wall when a rotary drilling rig penetrates through a water-permeable sandy pebble layer, and the process is characterized in that, for the collapsible stratum penetrated through by the rotary drilling rig, grouting liquid is injected from the sidewall of the drilling hole into the surrounding stratum by utilizing the water permeability of the collapsible stratum, diffused into a set range around the sidewall of the drilling hole and solidified to form a sidewall reinforcement structure; specifically, the rotary drilling and the active sidewall reinforcement are alternately performed, and the grouting is performed after the drilling; when the thickness of the collapsible stratum is not greater than the height of the drill bit, the grouting can be completed at one time by the grouting device when the drilling hole penetrates through the collapsible stratum; and when the thickness of the collapsible stratum is greater than the height of the drill bit, the grouting is performed by the grouting device in multiple stages. The application can assist in actively grouting and reinforcing the sidewall of the water-permeable sandy pebble layer when the rotary drilling rig penetrates through the water-permeable sandy pebble layer, prevent the sidewall from collapsing, and has the advantages of better sidewall protection effect, smaller construction difficulty, lower cost, higher construction safety and the like.

Description

Technical Field

[0001] This invention relates to the field of borehole construction technology. More specifically, this invention relates to an active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer. Background Technology

[0002] In pile foundation construction, rotary drilling rigs are the most common method for hole formation. When rotary drilling rigs penetrate permeable sand and gravel layers, the zero cohesion of this stratum, coupled with the disruption of the pressure balance between the inner and outer sides of the borehole wall caused by drilling, and the disturbance from the rotary drill bit, often leads to borehole wall collapse, resulting in quality and safety accidents. Borehole wall collapse during drilling can cause problems such as stuck drill, drill bit burial, surface subsidence, and casing misalignment; collapse after hole cleaning can result in excessive sediment buildup; and collapse during pile grouting can cause pile quality defects or even pile breakage. Even minor borehole wall collapse can cause pile diameter enlargement, which will manifest as a problem pile in subsequent low-strain pile integrity testing. Severe borehole wall collapses in pile foundation construction, especially those causing pile quality accidents, are extremely difficult to handle subsequently, resulting in significant direct economic losses and indirect losses in terms of construction time and reputation.

[0003] To prevent borehole wall collapse in gravel layers during rotary drilling, some projects have implemented measures such as using high-quality bentonite mud, adjusting mud specific gravity, controlling mud parameters, and optimizing construction management to prevent collapse. High-speed rail projects have also used Neptune chemical mud for wall protection, which has proven effective in reducing the probability of collapse in gravel layers. Many other projects, in addition to optimizing mud wall protection processes and controlling mud parameters, also employ long casings to prevent gravel layer collapse. The length of the casing is determined by the location and thickness of the gravel layer, and in some cases, even a full casing is used. While steel casings can effectively prevent borehole wall collapse in gravel layers, this method requires a large amount of steel, has a slow construction speed, and high construction costs. Furthermore, when the casing depth is significant, traditional construction machinery cannot install it, making both installation and removal difficult. Another method used in engineering projects is grouting to reinforce permeable sand and gravel layers. This allows the loose sand and gravel layer to solidify into a cohesive whole with the aid of grouting materials, increasing the cohesion of the sand and gravel layer, reducing permeability, and effectively preventing borehole wall collapse. This pre-reinforcement needs to be carried out on the ground surface, requiring detailed surveys of the pile hole locations beforehand and the arrangement of drilling and grouting equipment according to the geological conditions, resulting in a significant investment. In addition, the grouting fluid diffuses inside and outside the pile hole area, requiring a large grouting volume, and the diffusion of grouting material into the pile hole area can lead to a certain degree of material waste.

[0004] Therefore, to prevent the collapse of the sand and gravel layer during rotary drilling and to improve the quality of pile foundation drilling, it is essential to propose an engineering technology measure with better wall protection, lower construction difficulty, and lower cost through process innovation. Based on previous work, this application develops a construction method that utilizes rotary drilling to first drill holes and then actively reinforces the borehole wall with grouting when traversing easily collapsible strata. Summary of the Invention

[0005] One objective of this invention is to provide an active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer. This process involves rapidly and actively grouting the borehole wall to prevent collapse, and offers advantages such as better wall protection, easier construction, lower cost, and higher construction safety.

[0006] To achieve these objectives and other advantages according to the present invention, an active reinforcement process for borehole walls when a rotary drilling rig penetrates a permeable sand and gravel layer is provided. For easily collapsible strata penetrated by the rotary drilling rig, the permeability of the easily collapsible strata is utilized to inject grout from the borehole sidewall into the surrounding strata, diffusing it to a predetermined area around the borehole wall and solidifying it to form a reinforced wall structure. Specifically, the process alternates between rotary drilling and active wall reinforcement, employing a drilling-then-grouting method. When the thickness of the easily collapsible strata is no greater than the drill bit height, grouting can be performed in one step when the borehole penetrates the strata. When the thickness of the easily collapsible strata exceeds the drill bit height, grouting is performed in stages and multiple times using the grouting device. Specifically, grouting is performed for the first time when the strata exceed the drill bit height, and drilling continues after solidification. Each drilling operation is followed by sidewall grouting, with drilling and grouting alternating until the easily collapsible strata are penetrated.

[0007] Preferably, the grouting device includes an upper sealing mechanism, a lower sealing mechanism, and a sleeve connecting the upper and lower sealing mechanisms as a whole. The upper and lower sealing mechanisms extend into the borehole and abut against the borehole sidewall to form a sealed space between the upper sealing mechanism, the lower sealing mechanism, the sleeve, and the borehole sidewall. The corresponding borehole sidewall is the easily collapsible stratum to be grouted and reinforced. Multiple grouting discs are vertically spaced inside the sleeve, and multiple grouting pipes connected to the grouting discs are circumferentially spaced. The multiple grouting pipes pass through the sleeve to grout the sealed space so that the grout penetrates into the sidewall stratum. The main grouting pipe outside the stratum extends vertically from inside the sleeve to connect to the multiple grouting discs in sequence.

[0008] Preferably, multiple grouting pipes on multiple grouting plates are arranged in a one-to-one correspondence. An elastic bag is provided between any two adjacent rows of grouting pipes on the outer wall of the sleeve, forming an elastic space between the bag and the outer wall of the sleeve. An air supply pipe from outside the formation extends vertically from inside the sleeve into the formation and passes through the sleeve to connect to the elastic space. The elastic space is inflated or deflated through the air supply pipe.

[0009] Preferably, the upper sealing mechanism includes a first sealing disc and a second sealing disc arranged vertically and vertically, which are connected as a single unit. The first sealing disc contains a plurality of first sealing blocks that move linearly along the radial direction of the first sealing disc, and the second sealing disc contains a plurality of second sealing blocks that move linearly along the radial direction of the second sealing disc. When lowered, the first sealing blocks and the second sealing blocks are in close contact. After being lowered to a set position, the plurality of first sealing blocks and the plurality of second sealing blocks move outward along the corresponding radial direction until they are in close contact with the borehole sidewall. At this time, the partial structures of the plurality of first sealing blocks and the plurality of second sealing blocks are located within the first sealing disc and the second sealing disc. In the longitudinal direction, the plurality of first sealing blocks and the plurality of second sealing blocks are arranged alternately, and any adjacent first sealing blocks and second sealing blocks overlap.

[0010] Preferably, the lower sealing mechanism has the same structure as the upper sealing mechanism; the outer circumferential surface of the sleeve is flush with the outer circumferential surfaces of the upper and lower sealing mechanisms before they are lowered.

[0011] Preferably, the first sealing disc has multiple notches evenly spaced along its lower surface, with multiple first sealing blocks corresponding to each notch. A first rotating shaft is located at the center of the first sealing disc and is rotatably connected to it. Multiple elastic steel sheets perpendicular to the sidewalls of the first rotating shaft are evenly spaced along its circumference, with each elastic steel sheet corresponding to a first sealing block. The elastic steel sheets pass freely through the first sealing disc and connect to their respective first sealing blocks. A gap exists between the portion of the first rotating shaft connecting the elastic steel sheets and the first sealing disc. The elastic steel sheets are rigid. The second sealing disc has multiple notches evenly spaced along its upper surface, with multiple second sealing blocks corresponding to each notch. A second rotating shaft is located at the center of the second sealing disc and is rotatably connected to it. The second rotating shaft also has multiple elastic steel sheets, corresponding to the second sealing blocks, similar to those on the first rotating shaft. The diameter of the second rotating shaft is smaller than that of the first rotating shaft to avoid interference. The diameter of the second rotating shaft corresponding to the upper sealing mechanism is larger than that of the first rotating shaft corresponding to the lower sealing mechanism.

[0012] Preferably, the first and second sealing discs are hollow inside to allow the grouting main pipe, the air supply pipe, and the first and second rotating shafts corresponding to the lower sealing mechanism to pass freely through.

[0013] Preferably, the first and second rotating shafts corresponding to the lower sealing mechanism are complete cylindrical structures in the space outside the sleeve, and are connected by multiple vertically arranged support rods in the space of the sleeve, so that the grouting pipe and the air supply pipe can freely pass through the space formed by the multiple support rods.

[0014] Preferably, the top of the first and second rotating shafts corresponding to the upper sealing mechanism and the first and second rotating shafts corresponding to the lower sealing mechanism are all provided with handles for driving rotation. The top handles of the first and second rotating shafts corresponding to the upper sealing mechanism are connected by a detachable limiting rod when lowered, and the top handles of the first and second rotating shafts corresponding to the lower sealing mechanism are also connected by a detachable limiting rod when lowered.

[0015] Preferably, elastic blocks are provided on both sides of each elastic steel sheet, with one end connected to the corresponding sealing block and the other end of the elastic block connected to the corresponding sealing disc.

[0016] The present invention has at least the following beneficial effects:

[0017] This invention utilizes a sidewall grouting device to assist in alternating rotary drilling. The grouting device creates a sealed space within the borehole wall to be reinforced, allowing grout to be injected into the sidewall strata. This active grouting reinforcement of the borehole wall in the permeable sand and gravel layer prevents collapse, thereby improving construction safety and reducing costs. When pile foundation drilling through permeable sand and gravel layers, alternating between rotary drilling and active sidewall grouting provides rapid reinforcement and prevents borehole collapse. Compared to conventional long casing methods, this approach reduces steel consumption and increases construction speed, demonstrating significant potential for cost reduction and efficiency improvement.

[0018] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure when the present invention is deployed;

[0020] Figure 2 This is a schematic diagram of the structure of the sealed space formed after the present invention is lowered;

[0021] Figure 3 This is a cross-sectional view of the sleeve of the present invention;

[0022] Figure 4 This is a cross-sectional view of the sealing disc of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Drill hole; 2. Sleeve; 3. First rotating shaft; 4. Second rotating shaft; 5. Grouting main pipe; 6. Grouting disc; 7. Grouting pipe; 8. First sealing disc; 9. Second sealing disc; 10. First sealing block; 11. Second sealing block; 12. Elastic steel sheet; 13. Elastic bag; 14. Elastic block. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0026] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] This invention provides an active reinforcement process for borehole walls when a rotary drilling rig penetrates a permeable sand and gravel layer. For easily collapsible strata penetrated by the rotary drilling rig, the permeability of the strata allows grout to be injected from the borehole sidewall into the surrounding strata, spreading to a predetermined area around the borehole wall and solidifying to form a reinforced wall structure. Specifically, this involves alternating between rotary drilling and active wall reinforcement. Drilling is performed first, followed by grouting. When the thickness of the easily collapsible strata is no greater than the drill bit height, grouting can be completed in one step when the borehole penetrates the strata. When the thickness of the easily collapsible strata exceeds the drill bit height, grouting is performed in stages and multiple times using the grouting device. Specifically, grouting is performed once when the strata exceed the drill bit height, and drilling continues after solidification. Grouting is performed on the sidewalls with each drilling pass, alternating between drilling and grouting until the easily collapsible strata are penetrated.

[0028] In another technical solution, such as Figures 1 to 3As shown, the grouting device includes an upper sealing mechanism, a lower sealing mechanism, and a sleeve 2 that connects the upper sealing mechanism and the lower sealing mechanism as a whole. The upper sealing mechanism and the lower sealing mechanism extend into the borehole 1 and press against the side wall of the borehole 1 to form a sealed space between the upper sealing mechanism, the lower sealing mechanism, the sleeve 2 and the side wall of the borehole 1. The corresponding side wall of the borehole 1 is the easily collapsible stratum to be grouted and reinforced. Multiple grouting discs 6 are vertically spaced inside the sleeve 2, and multiple grouting pipes 7 connected to the grouting discs 6 are circumferentially spaced. Multiple grouting pipes 7 pass through the sleeve 2 to grout the sealed space so that the grout penetrates into the side wall stratum. The grouting main pipe 5 outside the stratum extends vertically from inside the sleeve 2 to connect to the multiple grouting discs 6 in sequence.

[0029] In the above technical solution, the central axes of the upper sealing mechanism, the lower sealing mechanism, and the sleeve 2 coincide to ensure the symmetry of the overall structure, the uniformity of the sealing space formation, and the uniformity of the grouting pressure in all directions of the sidewall. When the borehole 1 passes through the easily collapsible stratum, the entire sidewall grouting device is lowered to the sealing space to cover the easily collapsible stratum area. Taking advantage of the permeability of the easily collapsible stratum, the grout is injected from the sealing space of the sidewall to the periphery, diffuses to a certain range around the well wall, and solidifies to form a protective wall structure. Grout is injected under pressure into multiple grouting plates 6 through a grouting main pipe 5 on the outside. The grout is then forced into the sealing space through multiple grouting pipes 7 via the grouting plates 6. Grouting continues, and the grout permeates and diffuses into the stratum under the pressure of the sealing space, reinforcing the easily collapsible permeable sand and gravel layer.

[0030] In another technical solution, multiple grouting pipes 7 on multiple grouting plates 6 are arranged in a one-to-one correspondence. An elastic bag 13 is provided between any two adjacent rows of grouting pipes 7 on the outer wall of the sleeve 2, forming an elastic space between the bag and the outer wall of the sleeve 2. An air supply pipe from outside the formation extends vertically into the formation from inside the sleeve 2 and passes through the sleeve 2 to connect to the elastic space. The elastic space is inflated or deflated through the air supply pipe.

[0031] In the above technical solution, after the grout in the sealed space is filled, the pressure reaches a certain level and grouting can no longer continue. At this point, in order to accelerate the penetration of the grout and minimize the grout residue in the sealed space, the elastic bag 13 is inflated through the air supply pipe. The elastic bag 13 has strong elasticity and a certain degree of stretching elasticity, thus compressing the sealed space and promoting the penetration of the grout into the formation. After the reinforcement is completed, the elastic bag 13 can be retracted simply by deflating it again.

[0032] In another technical solution, the upper sealing mechanism includes a first sealing disk 8 and a second sealing disk 9 arranged sequentially from top to bottom and connected as a single unit. The first sealing disk 8 contains a plurality of first sealing blocks 10 that move linearly along the radial direction of the first sealing disk 8, and the second sealing disk 9 contains a plurality of second sealing blocks 11 that move linearly along the radial direction of the second sealing disk 9. Figure 1 As shown, during lowering, the first sealing block 10 and the second sealing block 11 are in close contact; Figure 2 As shown, after being lowered to the set position, multiple first sealing blocks 10 and multiple second sealing blocks 11 move outward along the corresponding radial direction until they are tightly against the side wall of the borehole 1. At this time, the partial structures of multiple first sealing blocks 10 and multiple second sealing blocks 11 are located inside the first sealing disk 8 and the second sealing disk 9, ensuring that there are no gaps in the radial direction of the first sealing blocks 10 and the second sealing blocks 11. In the longitudinal direction, multiple first sealing blocks 10 and multiple second sealing blocks 11 are arranged alternately and any adjacent first sealing blocks 10 and second sealing blocks 11 overlap.

[0033] In the above technical solution, to facilitate the smooth lowering of the entire device, both the upper and lower sealing mechanisms are designed with diameters smaller than the borehole diameter 1 during lowering. After successful lowering, the sealing blocks of the upper and lower sealing mechanisms are popped out and pressed tightly against the sidewall of the borehole 1 to form a sealed space suitable for grouting. The arrangement of the upper and lower sealing discs forms two sealing blocks that press tightly against the sidewall of the borehole 1, thus achieving longitudinal sealing through the staggered arrangement of the sealing blocks. Only a portion of the upper and lower sealing blocks moves radially outside the sealing discs, ensuring radial sealing.

[0034] In another technical solution, the lower sealing mechanism has the same structure as the upper sealing mechanism; the outer peripheral surface of the sleeve 2 is flush with the outer peripheral surfaces of the upper and lower sealing mechanisms before being lowered.

[0035] In another technical solution, such as Figure 1 , Figure 2 , Figure 4As shown, the first sealing disc 8 has multiple notches evenly spaced along its lower surface, each containing a corresponding first sealing block 10. A first rotating shaft 3 is centrally located on the first sealing disc 8 and rotatably connected to it. Multiple elastic steel sheets 12, perpendicular to the sidewalls of the first rotating shaft 3, are evenly spaced along its circumference. Each elastic steel sheet 12 corresponds precisely to one of the first sealing blocks 10. The elastic steel sheets 12 pass freely through the first sealing disc 8 and connect to the corresponding first sealing block 10. The portion of the first rotating shaft 3 connecting the elastic steel sheets 12 has a certain gap with the first sealing disc 8. The elastic steel sheet 12 has hardness. The second sealing disc 9 has multiple notches evenly spaced along its upper bottom surface, and multiple second sealing blocks 11 are correspondingly arranged in each notch. A second rotating shaft 4 is arranged at the center of the second sealing disc 9 and is rotatably connected to the second sealing disc 9. The second rotating shaft 4 is also provided with multiple elastic steel sheets 12 that are correspondingly connected to the multiple second sealing blocks 11, just like the first rotating shaft 3. The diameter of the second rotating shaft 4 is smaller than the diameter of the first rotating shaft 3 to avoid interference between the two. The diameter of the second rotating shaft 4 corresponding to the upper sealing mechanism is larger than the diameter of the first rotating shaft 3 corresponding to the lower sealing mechanism.

[0036] In the above technical solution, the initial state is as follows: Figure 1 and Figure 4 As shown, at this time, the elastic steel sheet 12 is partially wound around the rotating shaft, the elastic block 14 is in a compressed state, and the rotating shaft is in a locked state. By rotating the corresponding rotating shaft, the elastic steel sheet 12 is released, and under the outward elastic force of the elastic block 14, the sealing block is pushed out to press tightly against the side wall of the borehole 1. This is the final state, as shown. Figure 2 As shown. After reinforcement is completed, the drive shaft rotates in the opposite direction, causing the elastic steel sheet 12 to wrap around the shaft, retracting the sealing block into the sealing disc, thus allowing the side wall grouting device to be easily removed. The elastic steel sheet 12 has a certain degree of hardness, enabling both flexible rotation and rigid pushing of the sealing block.

[0037] In another technical solution, the first sealing disc 8 and the second sealing disc 9 are hollow inside to allow the grouting main pipe 5, the air supply pipe, and the first rotating shaft 3 and the second rotating shaft 4 corresponding to the lower sealing mechanism to pass freely through. As shown in the figure, the rotating shafts are all hollow cylindrical structures, which can be directly rotatably connected to the sealing discs on their outer walls, or the sealing discs can be expanded inward so that the lower part of the rotating shaft is located inside the sealing disc. When expanding inward, it is sufficient not to interfere with the vertical extension of other rotating shafts.

[0038] In another technical solution, the first rotating shaft 3 and the second rotating shaft 4 corresponding to the lower sealing mechanism are complete cylindrical structures in the space not where the sleeve 2 is located. They are connected by multiple vertically arranged support rods in the space where the sleeve 2 is located, so that the grouting pipe 7 and the air supply pipe can pass freely through the space formed by the multiple support rods, ensuring that the rotating shaft does not interfere with the connection and installation of the grouting pipe 7 and the air supply pipe.

[0039] In another technical solution, the top of the first rotating shaft 3 and the second rotating shaft 4 corresponding to the upper sealing mechanism and the first rotating shaft 3 and the second rotating shaft 4 corresponding to the lower sealing mechanism are all provided with handles for driving rotation. The top handles of the first rotating shaft 3 and the second rotating shaft 4 corresponding to the upper sealing mechanism are connected by a detachable limiting rod when lowered. The top handles of the first rotating shaft 3 and the second rotating shaft 4 corresponding to the lower sealing mechanism are also connected by a detachable limiting rod when lowered.

[0040] In the above technical solution, the handle is designed for easy rotation. The structure of the sidewall grouting device is designed according to the size of the borehole 1, so the rotation amplitude of each shaft can be accurately calculated in advance. Therefore, during lowering, the first shaft 3 and the second shaft 4 corresponding to the upper sealing mechanism and the first shaft 3 and the second shaft 4 corresponding to the lower sealing mechanism are respectively limited and fixed by two limiting rods. Figure 1 As shown, after the lowering is completed, the corresponding limiting rod restricts the rotating shaft, and the sealing block moves to press tightly against the side wall of the borehole 1 to achieve a seal. One end of the limiting rod is hinged to the handle at the top of the first rotating shaft 3, and the other end has a hook that is hung on the hanging ring on the handle at the top of the second rotating shaft 4 to achieve the limiting.

[0041] In another technical solution, elastic blocks 14 are provided on both sides of each elastic steel sheet 12, one end of which is connected to the corresponding sealing block, and the other end of the elastic block 14 is connected to the corresponding sealing disc.

[0042] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A process for actively reinforcing the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer, characterized in that, For easily collapsible strata penetrated by rotary drilling, the permeability of these strata is utilized to inject grout from the borehole sidewall into the surrounding strata, allowing it to diffuse within a designated area around the borehole wall and solidify, forming a protective wall reinforcement structure. Specifically, this involves alternating between rotary drilling and active wall reinforcement, employing a drilling-then-grouting approach. When the thickness of the easily collapsible strata is no greater than the drill bit height, grouting can be performed in one go as the borehole penetrates the strata. When the thickness of the easily collapsible strata exceeds the drill bit height, grouting is performed in stages and multiple times using the grouting device. Specifically, grouting is performed once when the borehole enters the strata and exceeds the drill bit height, followed by solidification and drilling. Each drilling pass is accompanied by sidewall grouting, with drilling and grouting alternating until the easily collapsible strata are penetrated. The grouting device includes an upper sealing mechanism, a lower sealing mechanism, and a sleeve connecting the upper sealing mechanism and the lower sealing mechanism as a whole. The upper sealing mechanism and the lower sealing mechanism extend into the borehole and press against the borehole sidewall to form a sealed space between the upper sealing mechanism, the lower sealing mechanism, the sleeve and the borehole sidewall. The corresponding borehole sidewall is the easily collapsible stratum to be grouted and reinforced. Multiple grouting discs are vertically spaced inside the sleeve, and multiple grouting pipes connected to the grouting discs are circumferentially spaced. Multiple grouting pipes pass through the sleeve to grout the sealed space so that the grout penetrates into the sidewall stratum. The grouting main pipe outside the stratum extends vertically from inside the sleeve to connect to the multiple grouting discs in sequence. The upper sealing mechanism includes a first sealing disc and a second sealing disc arranged vertically and connected as a single unit. The first sealing disc contains a plurality of first sealing blocks that move linearly along the radial direction of the first sealing disc, and the second sealing disc contains a plurality of second sealing blocks that move linearly along the radial direction of the second sealing disc. When lowered, the first sealing blocks and the second sealing blocks are in close contact. After being lowered to a set position, the plurality of first sealing blocks and the plurality of second sealing blocks move outward along the corresponding radial direction until they are in close contact with the borehole sidewall. At this time, the partial structures of the plurality of first sealing blocks and the plurality of second sealing blocks are located within the first sealing disc and the second sealing disc. In the longitudinal direction, the plurality of first sealing blocks and the plurality of second sealing blocks are arranged alternately, and any adjacent first sealing blocks and second sealing blocks overlap. The first sealing disc has multiple notches evenly spaced along its lower surface, each containing a corresponding first sealing block. A first rotating shaft is centrally located on the first sealing disc and rotatably connected to it. Multiple elastic steel plates, perpendicular to the sidewalls of the first rotating shaft, are evenly spaced along its circumference. Each elastic steel plate corresponds to a first sealing block, passing freely through the first sealing disc and connecting to its corresponding first sealing block. A gap exists between the portion of the first rotating shaft connecting the elastic steel plates and the first sealing disc. The elastic steel plates are rigid. The second sealing disc has multiple notches evenly spaced along its upper surface, each containing a corresponding second sealing block. A second rotating shaft is centrally located on the second sealing disc and rotatably connected to it. The second rotating shaft, like the first rotating shaft, also has multiple elastic steel plates corresponding to the second sealing blocks. The diameter of the second rotating shaft is smaller than that of the first rotating shaft to avoid interference. The diameter of the second rotating shaft corresponding to the upper sealing mechanism is larger than that of the first rotating shaft corresponding to the lower sealing mechanism.

2. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, Multiple grouting pipes on multiple grouting plates are arranged in a one-to-one correspondence. An elastic bag is provided between any two adjacent rows of grouting pipes on the outer wall of the sleeve, forming an elastic space between the bag and the outer wall of the sleeve. An air supply pipe from outside the formation extends vertically into the formation from inside the sleeve and passes through the sleeve to connect to the elastic space. The elastic space is inflated or deflated through the air supply pipe.

3. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, The lower sealing mechanism has the same structure as the upper sealing mechanism; the outer circumferential surface of the sleeve is flush with the outer circumferential surfaces of the upper and lower sealing mechanisms before they are lowered.

4. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, The first and second sealing discs are hollow inside to allow the grouting main pipe, the air supply pipe, and the first and second rotating shafts corresponding to the lower sealing mechanism to pass freely through.

5. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, The first and second rotating shafts corresponding to the lower sealing mechanism are complete cylindrical structures in the space outside the sleeve. They are connected by multiple vertically arranged support rods in the space of the sleeve, so that the grouting pipe and the air supply pipe can pass freely through the space formed by the multiple support rods.

6. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, The top of the first and second rotating shafts corresponding to the upper sealing mechanism and the first and second rotating shafts corresponding to the lower sealing mechanism are all provided with handles for driving rotation. The top handles of the first and second rotating shafts corresponding to the upper sealing mechanism are connected by a detachable limiting rod when lowered. The top handles of the first and second rotating shafts corresponding to the lower sealing mechanism are also connected by a detachable limiting rod when lowered.

7. The active reinforcement process for the borehole wall when a rotary drilling rig penetrates a permeable sand and gravel layer as described in claim 1, characterized in that, Each elastic steel sheet has an elastic block on both sides, with one end connected to the corresponding sealing block and the other end connected to the corresponding sealing disc.

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