Combined pin and grout plug and grout-tight blocking method

Abstract

The present application belongs to the technical field of disposable plugging stopper, and specifically provides a combined pin plugging stopper and a slurry sealing and blocking method. The combined pin plugging stopper comprises a stopper pipe, a first pin, a sliding structure, a deformation piece, an inner support, a steel ball, a second pin, a connector, a slurry overflow port and a slurry outlet pipe. The stopper pipe is fixedly connected with a grouting pipe through the first pin. The other end of the stopper pipe is arranged along the central axis of the grouting pipe and is connected with the slurry outlet pipe. The steel ball is arranged inside the side of the stopper pipe close to the slurry outlet pipe. The second pin is arranged between the steel ball and the slurry outlet pipe. The sliding structure is sleeved on the stopper pipe and is provided with a plurality of deformation pieces. The end of the sliding structure close to the slurry outlet pipe is connected with the slurry overflow port arranged on the slurry outlet pipe through the connector. The inner support is arranged on the stopper pipe and between the adjacent two deformation pieces. The present application can solve the problem of sealing failure or difficult recovery in the high-pressure grouting process caused by the structural and technological defects of the existing plugging stopper.

Description

Technical Field

[0001] This invention belongs to the field of disposable grout stopper technology, and relates to a combined pin grout stopper and a grout sealing method. Background Technology

[0002] During drilling, geological exploration, and downhole operations, it is often necessary to grout, seal, or reinforce specific formations. Grout stoppers, as a crucial downhole tool, are used to seal the borehole annulus, prevent the disorderly backflow of grout, and ensure that the grouting pressure effectively acts on the target formation. They are a core component for achieving precise and efficient grouting operations. Traditional grout stoppers mostly employ mechanical expansion or rubber capsule structures, relying on external pressure to expand and adhere to the borehole wall to achieve a seal.

[0003] However, existing grout stoppers have significant limitations in practical applications. First, in complex formations or under irregular borehole wall conditions, traditional grout stoppers are prone to seal failure due to uneven contact and poor fit, leading to grout leakage (i.e., "unable to stop the grout"), which seriously affects grouting quality and operational efficiency. Second, the unsealing or recovery process of some grout stoppers after grouting is complex, and there is even a risk that they cannot be removed smoothly, increasing the construction period and cost. In addition, conventional grout stoppers have limited adaptability to formation pressure; under large pressure fluctuations, they are prone to "creeping" or seal failure, resulting in insufficient reliability.

[0004] In summary, although the industry has made some improvements to the structure and materials of grout stoppers, such as using multi-stage seals or more flexible rubber sleeves, there is still room for improvement in ensuring the reliability of initial setting and maintaining a stable seal under dynamic pressure. Especially in deep wells, ultra-deep wells, or under complex geological conditions, higher requirements are placed on the setting reliability, sealing stability, and recyclability of grout stoppers. Therefore, there is an urgent need for a new type of grout stopper structure that can effectively solve the problems of incomplete sealing, unreliable sealing, and difficulty in recycling that are common in existing technologies. Summary of the Invention

[0005] This invention provides a combined pin grout stop plug, wherein the combined pin grout stop plug is pre-installed in the sleeve valve tube and connected to the external grouting equipment through the grouting pipe; and it includes a plug tube, a first pin, a sliding structure, a deformable component, an inner support, a steel ball, a second pin, a connector, an overflow port and a grout outlet pipe;

[0006] One end of the plug tube is inserted into the grouting pipe and fixed to the grouting pipe by the first pin;

[0007] The other end of the plug extends along the central axis of the grouting pipe, and the extended end of the plug is connected to the grout outlet pipe.

[0008] A steel ball is installed inside the plug tube on the side near the slurry outlet tube;

[0009] The second pin is positioned between the steel ball and the slurry outlet pipe;

[0010] The sliding structure is sleeved on the plug pipe. Several deformable parts are installed on the end of the sliding structure near the grouting pipe along the central axis of the grouting pipe. The end of the sliding structure near the grout outlet pipe is connected to the overflow port on the grout outlet pipe through a connector.

[0011] The inner support is disposed on the plug tube and between two adjacent deformable parts;

[0012] When external grouting equipment injects grout into the grouting pipe, the grout flows through the plug pipe to the steel ball and impacts the steel ball;

[0013] As the grouting pressure increases, the impact of the grout on the steel ball also increases, causing the second pin to break. The high-pressure grout, together with the steel ball, impacts the overflow port. The overflow port drives the connector and sliding structure. The sliding structure pushes the deformation component to deform. The deformation component abuts against the inner support and fits tightly against the sleeve valve tube, achieving the sealing of the grout stop plug. The grout in the plug tube overflows along the overflow port on the grout outlet pipe, penetrates the sleeve valve tube, and is injected into the external formation, completing the grouting.

[0014] After grouting is completed, the first pin is cut off by lifting the pipe from the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position and the grouting pipe is retrieved.

[0015] Furthermore, a steel ball limiter is installed inside the plug tube, positioned between the steel ball and the grouting pipe.

[0016] Furthermore, the deformable component is provided with a soft steel structural component.

[0017] Furthermore, the thickness of the deformable part is set to 1.5mm-2.5mm, and the ductility strength of the deformable part is set to 200MPa-300MPa.

[0018] Furthermore, the deformable component is configured as a bowl-shaped structure, with the smaller end of the deformable component connected to the sliding structure, and the larger end of the deformable component deformed and then tightly attached to the sleeve valve tube.

[0019] Furthermore, the inner support is made of high-strength steel and has a thickness of 2mm-3mm.

[0020] Furthermore, the second pin is configured as a brittle steel structural component with a shear strength of 5MPa-10MPa.

[0021] Furthermore, an outer steel partition is provided on the deformable part. The outer steel partition is fixed to the plug tube by welding and is located on the side of the inner support away from the deformable part.

[0022] Furthermore, the combined pin stopper also includes a rubber plug assembly;

[0023] The rubber plug assembly includes a mounting hole on the sleeve valve tube and a rubber plug mounted on the mounting hole; the rubber plug is configured as an elastic soft rubber structural component and has at least one overflow hole.

[0024] As a further aspect of the present invention, the present invention also provides a method for sealing off slurry, comprising the following steps:

[0025] Step 1: Assemble the combined pin-stop plug as described above, and pre-install it in the sleeve valve tube before connecting it to the grouting pipe;

[0026] Step 2: Grouting;

[0027] External grouting equipment injects grout into the grouting pipe. The grout flows through the plug and impacts the steel ball. At this time, the grouting pressure is low, and the second pin is holding the steel ball in place before it breaks.

[0028] The grout placed in the plug tube is continuously injected to increase the pressure. As the grouting pressure gradually increases, the second pin breaks. The high-pressure grout, together with the steel ball, impacts the overflow port. The overflow port drives the connector and sliding structure. The sliding structure pushes the deformation component to deform. The deformation component abuts against the inner support and tightly adheres to the sleeve valve tube, thus achieving the grout stop plug sealing.

[0029] The grout overflows from the overflow port on the grout outlet pipe, penetrates the sleeve valve pipe and is injected into the external strata, completing the grouting;

[0030] Step 3: After grouting is completed, the first pin is cut off by lifting the pipe from the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position, and the grouting pipe is retrieved.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a combined pin-type grout stopper that solves the problem of sealing failure or recovery difficulties during high-pressure grouting caused by structural and technological defects in existing grout stoppers. Specifically, the invention employs a combination mechanism of a second pin and a first pin, which facilitates the gradual release of the steel ball under grouting pressure and achieves deformation sealing. Subsequent pipe lifting and cutting achieves permanent fixation. Furthermore, this application controls the fracture of the second pin by grouting pressure. The high-pressure grout, in conjunction with the steel ball, impacts the overflow port, causing the sliding structure to push the cup-shaped soft steel to deform uniformly, ensuring a tight fit with the sleeve valve pipe and preventing grout leakage. The soft structure of the cup-shaped soft steel enhances its ductility and stability, while the inner support and outer steel partition provide guidance and protection, achieving a reliable seal. The grouting method protected by this invention is simple in procedure, easy to operate, and highly practical.

[0033] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a front cross-sectional schematic diagram of a combined pin grout stopper according to an embodiment of the present invention.

[0036] in:

[0037] 1. Grouting pipe, 2. Plug pipe, 3. First pin, 4. Sliding structure, 5. Outer steel partition, 6. Deformable part, 7. Inner support, 8. Steel ball, 9. Steel ball limiter, 10. Second pin, 11. Connector, 12. Overflow port, 13. Valve sleeve, 14. Grout outlet pipe, 15. Sealing space, 16. Mounting hole. Detailed Implementation

[0038] To make the above-mentioned objectives, features, and advantages of the present invention clearer and easier to understand, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the accompanying drawings of the present invention are all in a simplified form and use non-precise proportions, and are only used to facilitate and clearly assist in illustrating the implementation of the present invention; the "several" mentioned in the present invention are not limited to the specific number shown in the examples in the accompanying drawings; the orientations or positional relationships indicated by terms such as "front," "middle," "rear," "left," "right," "up," "down," "top," "bottom," and "center" mentioned in the present invention are all based on the orientations or positional relationships shown in the accompanying drawings of the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation, nor should they be construed as limitations on the present invention.

[0039] Example 1:

[0040] See Figure 1 As shown, the present invention provides a combined pin grout stop plug, specifically relating to a retractable and cut-off combined pin grout stop plug. The combined pin grout stop plug is pre-installed in the sleeve valve tube 13 and connected to external grouting equipment through the grouting pipe 1. Specifically, the combined pin grout stop plug includes a plug tube 2, a first pin 3, a sliding structure 4, a deformable component 6, an inner support 7, a steel ball 8, a second pin 10, a connector 11, an overflow port 12, and a grout outlet pipe 14.

[0041] One end of the plug tube 2 is inserted into the grouting pipe 1 and is fixedly connected to the grouting pipe 1 by the first pin 3;

[0042] The other end of the plug tube 2 extends along the central axis of the grouting pipe 1, and the extended end of the plug tube 2 is connected to the grout outlet pipe 14.

[0043] A steel ball 8 is installed inside the plug tube 2 on the side near the slurry outlet tube 14;

[0044] The second pin 10 is disposed between the steel ball 8 and the slurry outlet pipe 14;

[0045] The sliding structure 4 is sleeved on the plug tube 2. Several deformable parts 6 are installed on the end of the sliding structure 4 near the grouting pipe 1 along the central axis of the grouting pipe 1. The end of the sliding structure 4 near the grout outlet pipe 14 is connected to the overflow port 12 on the grout outlet pipe 14 through the connector 11.

[0046] The inner support 7 is disposed on the plug tube 2 and between two adjacent deformable parts 6;

[0047] When external grouting equipment injects grout into grouting pipe 1, the grout flows through plug pipe 2 to steel ball 8 and impacts steel ball 8.

[0048] As the grouting pressure increases, the impact of the grout on the steel ball 8 also increases, causing the second pin 10 to break. The high-pressure grout (in this embodiment, high-pressure grout refers to grout with a pressure greater than or equal to 10 MPa) works in conjunction with the steel ball 8 to impact the overflow port 12. The overflow port 12 drives the connector 11 and the sliding structure 4. The sliding structure 4 pushes the deformation member 6 to deform. The deformation member 6 abuts against the inner support 7 and is tightly attached to the sleeve valve tube 13, thus achieving the sealing of the grout stop plug. The grout in the plug tube 2 overflows along the overflow port 12 on the grout outlet pipe 14, penetrates the sleeve valve tube 13, and is injected into the external formation, completing the grouting.

[0049] After grouting is completed, the first pin 3 is cut off by lifting the pipe from the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position and the grouting pipe 1 is recovered.

[0050] Preferably, in order to limit the movement of the steel ball 8, a steel ball limiter 9 is also provided in the plug tube 2, and the steel ball limiter 9 is located between the steel ball 8 and the grouting pipe 1.

[0051] Preferably, in order to enable the deformable component 6 to deform under the pressure of the slurry, the deformable component 6 is provided with a soft steel structural component (specifically, the soft steel is selected as cold-rolled soft steel), and the thickness of the deformable component 6 is set to 1.5mm-2.5mm (specifically, in this embodiment, the thickness of the deformable component 6 is preferably set to 2mm), and the ductility strength is set to 200MPa-300MPa (specifically, in this embodiment, the ductility strength of the deformable component 6 is preferably set to 250MPa), so as to have higher ductility and deformation capacity than traditional slurry-stopping materials, which facilitates uniform deformation under the push of the sliding structure 4.

[0052] Further preferably, in order to limit the deformation direction of the deformable part 6, the deformable part 6 is preferably configured as a bowl-shaped structure, and the smaller end of the deformable part 6 is connected to the sliding structure 4; after deformation, the deformable part 6 increases the contact area with the sleeve valve tube 13, which is beneficial to enhance the sealing and stability of the slurry stop plug, while preventing slurry backflow or leakage.

[0053] Preferably, the inner support 7 is a high-strength steel structural component (specifically, the high-strength steel is selected from the NM series), and the thickness of the inner support 7 is set to 2mm-3mm (specifically, in this embodiment, the thickness of the inner support 7 is preferably set to 2.5mm), which is used to guide the deformation direction of the deformable component 6 and ensure that it fits tightly against the inner wall of the sleeve valve tube 13 after deformation.

[0054] Preferably, the second pin 10 is a brittle steel structural component (specifically, the brittle steel is selected from at least one of blue brittle steel, low-temperature brittle steel, tempered brittle steel, and stress-induced brittle steel) so that it remains intact when the grouting pressure is low (less than 5 MPa) to limit the position of the steel ball 8; when the grouting pressure increases to 10 MPa-25 MPa, the second pin 10 breaks under the impact of the steel ball 8 to release the steel ball 8, so that the high-pressure grout and the steel ball 8 can work together to rush towards the overflow port 12.

[0055] More preferably, the second pin 10 is configured as a cylindrical structure, and the length of the second pin 10 is set to 20-40mm (specifically, in this embodiment, the length of the second pin 10 is preferably set to 20mm), and the diameter is set to 5mm-20mm (specifically, in this embodiment, the diameter of the second pin 10 is preferably set to 10mm); the shear strength of a single second pin 10 is set to 5MPa-10MPa (specifically, in this embodiment, the shear strength of the second pin 10 is preferably set to 5MPa).

[0056] Preferably, the diameter of the steel ball 8 is set to 30-50mm (specifically, in this embodiment, the diameter of the steel ball 8 is preferably set to 40mm), and the material of the steel ball 8 is set to high-hardness steel (specifically, HSS is selected as the high-hardness steel) to ensure sufficient impact force.

[0057] Preferably, the length of the overflow port 12 is set to 100-200mm (specifically, in this embodiment, the length of the overflow port 12 is preferably set to 100mm) to ensure that the slurry overflows evenly.

[0058] Preferably, the inner wall diameter of the sleeve valve tube 13 is set to 40-60mm (specifically, in this embodiment, the inner wall diameter of the sleeve valve tube 13 is preferably set to 50mm), which fits tightly with the deformable part 6 after deformation to form a sealed pressure chamber.

[0059] As a further embodiment, in order to prevent the deformable part 6 from being over-deformed, an outer steel partition 5 is also provided on the deformable part 6. The outer steel partition 5 is fixed to the plug tube 2 by welding and is provided on the side of the inner support 7 away from the deformable part 6, so as to provide additional support for the inner support 7 and thus prevent the deformable part 6 from being over-deformed.

[0060] As a further solution in this embodiment, theoretically, the impact path of the steel ball 8 coincides with the deformation boundary of the deformable part 6; in actual process, the impact path of the steel ball 8 does not completely coincide with part of the deformation boundary of the deformable part 6. At this time, the sliding structure 4 slides further due to the impact of the steel ball 8, but at this time, the second pin 10 will consume some impact energy due to its breakage. Therefore, the slurry needs to further accumulate kinetic energy to further improve the cooperative impact force of the steel ball 8 and the slurry.

[0061] Specifically, during the deformation process, the deformable component 6 gradually undergoes expansion deformation. The strength of the deformable component 6 is moderate compared to other components, and the deformation rate is controllable. Under the impact of the slurry and the steel ball 8, the deformable component 6 gradually becomes fixed. The deformation boundary formed at this time is defined as the deformation boundary of the deformable component 6.

[0062] Under the impact of the slurry and the steel ball 8, the deformation boundary of the deformable part 6 continues to expand, and the strength of the deformable part 6 continues to adapt. At this time, the slurry in the overflow port 12 is squeezed outward along the normal direction of the deformation boundary of the deformable part 6. Under the action of impact, deformation and squeezing, the intensity of this combined action is greater than the remaining elasticity of the deformable part 6, and the outer deformable part 6 undergoes fixed deformation. This process marks the complete closure of the slurry stop plug.

[0063] Under continuous impact, the deformable part 6 undergoes fixed deformation. The remaining deformable part 6 outside the deformation boundary is affected by the slurry in the overflow port 12 and adheres tightly to the inner wall of the sleeve valve tube 13. It is squeezed by the deformation energy of the sleeve valve tube 13, and some of the slurry with high kinetic energy is squeezed out to the external formation.

[0064] Under the pressure of the grout, the deformable part 6 comes into close contact with the sleeve valve tube 13. The grout outlet tube 14 and the bottom of the sleeve valve tube 13 form a closed pressure chamber. The grout accumulates in the closed pressure chamber until the grouting pressure exceeds the compressive strength of the outer casing material. At this time, the outer casing material is punctured, forming a uniform grouting channel, thus achieving the purpose of controlling the grouting.

[0065] As a further embodiment, the first pin 3 is cut off by the drilling rig after grouting is completed, thereby permanently fixing the grout stop plug. The material strength of the first pin 3 is designed to be easy to break under the lifting force, but to remain intact during the grouting process, ensuring the stability of the entire structure during the grouting stage. After cutting, the grouting pipe 1 can be recycled, reducing material waste.

[0066] As a further embodiment, the combined pin grout stopper also includes a rubber plug assembly;

[0067] The rubber plug assembly includes a mounting hole 16 provided on the sleeve valve tube 13 and a rubber plug installed on the mounting hole 16; the rubber plug is configured as an elastic soft rubber structural component and is provided with at least one overflow hole.

[0068] When the deformable part 6 abuts against the inner support 7 and is tightly attached to the sleeve valve tube 13, at the same time, the rubber plug is squeezed by the mounting hole 16 to keep the overflow hole in a sealed state, thereby forming a sealed space 15 between the inner support 7 and the sleeve valve tube 13.

[0069] When the slurry in the plug tube 2 overflows along the overflow port 12 on the slurry outlet pipe 14 and reaches the preset pressure value of the rubber plug, the slurry flows out through the overflow hole.

[0070] Preferably, the diameter of a single overflow hole is set to 1mm-2mm, and an interference fit is used between a single rubber plug and a single mounting hole, so that the overflow hole can be sealed when the rubber plug is squeezed through the mounting hole, and the rubber plug can be opened when subjected to the pressure of the slurry while preventing the rubber plug from being directly flushed out.

[0071] Example 2:

[0072] The present invention also provides a slurry sealing method using the aforementioned combined pin slurry stop plug, comprising the following steps:

[0073] Step S1: Position the stop plug in the valve tube 13 and inject grout into the grouting tube 1 through an external grouting device. The grout flows through the plug tube 2 and impacts the steel ball 8. At this time, the grouting pressure is low and the second pin 10 is pressed against the steel ball 8 and has not yet broken.

[0074] Step S2: Continue pressurized grouting. As the grouting pressure gradually increases, the second pin 10 breaks. The high-pressure grout, together with the steel ball 8, impacts the overflow port 12. The overflow port 12 drives the connector 11 and the sliding structure 4. The sliding structure 4 pushes the deformation component 6 to deform. The deformation component 6 abuts against the inner support 7 and is tightly attached to the sleeve valve pipe 13, thus achieving the sealing of the grout stop plug. The grout overflows along the overflow port 12 on the grout outlet pipe 14, penetrates the sleeve valve pipe 13, and is injected into the external strata, completing the grouting.

[0075] Step S3: After grouting is completed, the first pin 3 is cut off by lifting the pipe from the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position and the grouting pipe 1 is recovered.

[0076] Optionally, the pressurized grouting uses a pressure of 10-30 MPa.

[0077] Optionally, the deformation boundary of the deformable element 6 is determined by the pushing of the sliding structure 4 and the impact of the grout, and its expansion range can be adjusted according to the grouting pressure.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A combined pin grout stopper, wherein the combined pin grout stopper is integrally pre-installed in a sleeve valve tube (13) and connected to an external grouting device via a grouting pipe (1); characterized in that, It includes a plug tube (2), a first pin (3), a sliding structure (4), a deformable component (6), an inner support (7), a steel ball (8), a second pin (10), a connector (11), an overflow port (12), and a slurry outlet pipe (14). One end of the plug tube (2) is inserted into the grouting pipe (1) and fixed to the grouting pipe (1) by the first pin (3); The other end of the plug tube (2) extends along the central axis of the grouting pipe (1), and the extended end of the plug tube (2) is connected to the grout outlet pipe (14); A steel ball (8) is installed inside the plug tube (2) on the side near the slurry outlet tube (14). The second pin (10) is disposed between the steel ball (8) and the slurry outlet pipe (14); The sliding structure (4) is sleeved on the plug pipe (2). Several deformable parts (6) are installed on the end of the sliding structure (4) near the grouting pipe (1) along the central axis of the grouting pipe (1). The end of the sliding structure (4) near the grout outlet pipe (14) is connected to the overflow port (12) on the grout outlet pipe (14) through the connector (11). The inner support (7) is provided on the plug tube (2) and is located between two adjacent deformable parts (6); When the external grouting equipment injects grout into the grouting pipe (1), the grout flows through the plug pipe (2) to the steel ball (8) and impacts the steel ball (8); As the grouting pressure increases, the impact of the grout on the steel ball (8) also increases, causing the second pin (10) to break. The high-pressure grout, together with the steel ball (8), impacts the overflow port (12). The overflow port (12) drives the connector (11) and the sliding structure (4). The sliding structure (4) pushes the deformation component (6) to deform. The deformation component (6) abuts against the inner support (7) and is tightly attached to the sleeve valve tube (13), thus achieving the sealing of the grout stop plug. The grout in the plug tube (2) overflows along the overflow port (12) on the grout outlet pipe (14), penetrates the sleeve valve tube (13), and is injected into the external stratum, completing the grouting. After grouting is completed, the first pin (3) is cut off by lifting the pipe of the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position and the grouting pipe (1) is recovered.

2. The combined pin stopper according to claim 1, characterized in that, A steel ball limiter (9) is also provided inside the plug tube (2), and the steel ball limiter (9) is located between the steel ball (8) and the grouting pipe (1).

3. The combined pin stopper according to claim 1, characterized in that, The deformable component (6) is provided with a soft steel structural component.

4. The combined pin stopper according to claim 3, characterized in that, The thickness of the deformable part (6) is set to 1.5mm-2.5mm, and the ductility strength of the deformable part (6) is set to 200MPa-300MPa.

5. The combined pin stopper according to claim 3 or 4, characterized in that, The deformable part (6) is configured as a bowl-shaped structure, and the smaller end of the deformable part (6) is connected to the sliding structure (4), and the larger end of the deformable part (6) is deformed and then closely attached to the sleeve valve tube (13).

6. The combined pin stopper according to claim 5, characterized in that, The inner support (7) is a high-strength steel structural component, and the thickness of the inner support (7) is set to 2mm-3mm.

7. The combined pin stopper according to claim 6, characterized in that, The second pin (10) is a brittle steel structural component with a shear strength of 5MPa-10MPa.

8. The combined pin stop plug according to claim 6 or 7, characterized in that, An outer steel partition (5) is also provided on the deformable part (6). The outer steel partition (5) is fixed to the plug tube (2) by welding and is located on the side of the inner support (7) away from the deformable part (6).

9. The combined pin stopper according to claim 8, characterized in that, It also includes rubber stopper assemblies; The rubber plug assembly includes a mounting hole (16) provided on the sleeve valve tube (13) and a rubber plug installed on the mounting hole (16); the rubber plug is configured as an elastic soft rubber structure and has at least one overflow hole.

10. A method for sealing off slurry, characterized in that, Includes the following steps: Step 1: Assemble the combined pin grout stop plug as described in claim 9, and pre-install it in the sleeve valve tube (13) and then connect it to the grouting pipe (1); Step 2: Grouting; External grouting equipment injects grout into the grouting pipe (1). The grout flows through the plug pipe (2) and impacts the steel ball (8). At this time, the grouting pressure is low, and the second pin (10) is pressed against the steel ball (8) and has not yet broken. The grout placed in the plug tube (2) is continuously injected to increase the pressure. As the grouting pressure gradually increases, the second pin (10) breaks. The high-pressure grout, together with the steel ball (8), impacts the overflow port (12). The overflow port (12) drives the connector (11) and the sliding structure (4). The sliding structure (4) pushes the deformation part (6) to deform. The deformation part (6) abuts against the inner support (7) and tightly adheres to the sleeve valve tube (13), thus achieving the sealing of the grout stop plug. The grout overflows from the overflow port (12) on the grout outlet pipe (14), penetrates the sleeve valve pipe (13) and is injected into the external strata to complete the grouting; Step 3: After grouting is completed, the first pin (3) is cut off by lifting the pipe of the upper drilling rig, so that the grout stop plug is permanently fixed at the grouting position and the grouting pipe (1) is recovered.

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