Coal mine underground deep hole spiral screen pipe cooperative driving hole protection device and method

Abstract

According to the coal mine underground deep hole spiral screen pipe cooperative driving hole protecting device and method, a high-pressure medium thrust and drill rod rotating axial force cooperative driving mechanism is adopted, the resistance bottleneck during deep hole screen pipe lowering is effectively broken through, it can be ensured that a 300-500 m deep hole full-hole section screen pipe is smoothly lowered, and the problem that in a traditional method, the deep hole screen pipe is difficult to lower is solved; meanwhile, the spiral device on the outer side of the screen pipe is unique in design, collapse objects can be effectively prevented from directly covering the extraction hole when the drilled hole collapses, the extraction hole is prevented from being blocked, the anti-blocking capacity is greatly improved, internal thread connection at the two ends of the screen pipe is matched, the operation process is simplified, and the connection reliability is improved.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas control technology, and specifically relates to a deep-hole spiral screen tube collaborative drive hole protection device and method in coal mines. Background Technology

[0002] In coal mine gas drainage operations, borehole protection is a crucial step in ensuring drainage efficiency and extending drainage service time. Currently, ordinary boreholes in coal mines are mostly protected by manually pushing screen pipes. However, with the widespread application of directional drilling rigs, the drilling depth has reached 300-500m, and the drawbacks of manual pushing have become increasingly apparent: due to the depth of the borehole and the unevenness of the borehole wall, the resistance during screen pipe lowering increases sharply, often exceeding the limit of manual pushing force. This not only causes the construction time of a 100m deep hole to exceed 3 hours, but also makes it difficult to lower the screen pipe for the entire borehole section in holes deeper than 300m. As a result, a large number of boreholes cannot achieve full borehole protection, seriously affecting the subsequent gas drainage effect.

[0003] Meanwhile, existing borehole protection technologies are inadequate in preventing blockages. Manually pushed screens are mostly straight-cylinder or simple spiral structures. Straight-cylinder structures provide insufficient radial support to the borehole wall, resulting in a collapse rate exceeding 50% in fractured strata. Simple spiral structures, due to improper spiral parameter design, fail to provide effective protective support, allowing coal and rock fragments to easily "lock" the screen, leading to a blockage rate as high as 58% within 30 days. Once a localized borehole collapse occurs, the gas drainage channel in the exposed section will be blocked, causing the gas extraction concentration to plummet from the initial 25% to below 8%, significantly shortening the borehole's service life. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a deep-hole spiral screen tube co-driven hole protection device and method in coal mines, which overcomes the bottleneck of resistance during the lowering of deep-hole screen tubes through the spiral device and co-driven mechanism.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A deep-hole spiral screen tube co-driven hole protection device for coal mines includes a drilling rig, a hollow drill rod, an openable and closable drill bit connected to the end of the hollow drill rod, and a pushing device disposed at the rear end of the hollow drill rod, wherein the pushing device is fixed on the drilling rig. The pushing device is configured as a sealed cavity, and a first through hole and a second through hole are coaxially arranged on both sides of the sealed cavity. A third through hole for introducing high pressure medium into the sealed cavity is also opened at the top. The front end of the first through hole is provided with an extension section that is threadedly connected to the hollow drill rod and rotates with the sealed cavity through the provided bearing assembly. The hollow drill rod is also fitted with a spiral screen tube with spiral blades on the outer wall. The spiral blades are in annular clearance fit with the hollow drill rod, and the spiral screen tube is fed into the hollow drill rod through the second through hole and the first through hole.

[0006] Both the first and second through holes are equipped with sealing sleeves for sealing.

[0007] The first through hole is sealed by a sleeved rotary sealing assembly, and the second through hole is sealed by a fitted lip-shaped sealing sleeve.

[0008] The first end of the spiral screen tube is also equipped with a fixing device, which includes a connector, a push rod movably inserted into the front end of the connector, and a rotatably arranged limiting claw. The front end of the push rod is configured as a cam structure that presses against the limiting claw and is pressed down under external force to drive the limiting claw to rotate and unfold. The rear end of the push rod located behind the limiting claw is also equipped with a limiting baffle and a pressing spring. The pressing spring is limited to the rear side of the limiting baffle and moves with the push rod.

[0009] The limiting claw is provided in multiple parts, and its maximum outer diameter after opening is larger than the diameter of the drill hole. The surface of the limiting claw is also provided with barbed anti-slip teeth.

[0010] The cross-section of the spiral blade is trapezoidal, and the angle between the side of the spiral blade and the axis of the spiral screen tube is 85°~89°.

[0011] The spiral screen tube has extraction holes, which are located at the bottom of the groove between the spiral blades, and the hole diameter is 2~4mm.

[0012] The ends of the spiral screen tubes are provided with matching internal / external threads for connecting the screen tubes.

[0013] A method for a deep-hole spiral screen tube co-driven borehole protection device in coal mines includes the following steps: (1) Use the drilling rig and drilling tools to connect the openable and closable drill bit to drill to the designed hole depth, and withdraw the drill after cleaning the hole; (2) A rotary sealing assembly is installed in the first through hole, and the end section of the hollow rotating rod is threadedly connected to the first through hole of the pushing device, so that the hollow drill rod and the first through hole can rotate synchronously and dynamically seal. (3) The first section of the spiral screen tube is fed into the hollow drill rod through the second through hole and the high pressure medium is introduced into the pushing device through the third through hole of the pushing device. The high pressure medium enters the hollow drill rod and generates an axial force at the spiral blade on the outside of the spiral screen tube, pushing the spiral screen tube into the hole. (4) When the outer side of the first section of the spiral screen tube is exposed for 30cm to 50cm, a new spiral screen tube segment is connected, and the hollow drill rod is driven to rotate to generate axial force with the spiral blades on the outer side of the spiral screen tube. The spiral screen tube is then driven into the hole in conjunction with the high-pressure medium. (5) Repeat step (4) and connect multiple sections of spiral screen tube in sequence until the spiral screen tube is lowered to the bottom of the hole. The spiral screen tube passes through the openable and closable drill bit by axial force, and the fixing device at the first end of the spiral screen tube is pushed by the top rod to unfold the limiting claw and insert it into the hole wall under the action of the reaction force at the bottom of the hole, thereby fixing the spiral screen tube to remain in the hole. (6) After the spiral screen tube is lowered, drive the hollow drill rod to rotate in the forward direction and slowly withdraw the hollow drill rod and the openable drill bit connected to the end of the hollow drill rod.

[0014] The beneficial effects of this invention are: (1) This invention discloses a deep-hole spiral screen tube collaborative drive hole protection device and method in coal mines. The collaborative drive mechanism of "high pressure medium thrust + drill rod rotation axial force" effectively breaks through the resistance bottleneck when the deep-hole screen tube is lowered, and can ensure the smooth lowering of the screen tube in the entire hole section of 300~500m deep hole, solving the problem of difficult lowering of deep-hole screen tube in traditional methods. At the same time, the spiral device on the outside of the screen tube is ingeniously designed. When the hole collapses, it can effectively prevent the collapse material from directly covering the extraction hole, avoiding the extraction hole from being blocked, and greatly improving the anti-blocking ability. With the internal thread connection at both ends of the screen tube, it not only simplifies the operation process, but also enhances the reliability of the connection.

[0015] (2) The spiral screen pipe hole protection device and lowering method in coal mines can significantly reduce the resistance of deep hole screen pipe lowering and improve the lowering efficiency through the rationally designed spiral device and collaborative drive mechanism. The unique spiral structure can enhance the support capacity of the hole wall, greatly reduce the probability of hole wall collapse and drainage hole blockage, thereby ensuring gas drainage efficiency, extending the drilling service time, and providing reliable technical support for coal mine gas drainage work.

[0016] (3) By optimizing the structural parameters of the spiral screen tube, such as the height of the spiral blades, the pitch, the cross-sectional shape, and the layout of the extraction holes, the service life of the gas extraction channel has been extended, the extraction concentration has been maintained at more than 20% for a long time, the drilling service cycle has been extended to more than 12 months, and the high efficiency of deep hole protection has been achieved. This has significantly enhanced the stability and sustainability of underground gas extraction in coal mines and provided efficient and reliable technical support for coal mine gas control. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional view of the pushing device; Figure 3 This is a schematic diagram of the spiral screen tube structure; Figure 4 This is a structural schematic diagram of the fixing device; Figure 5 This is an unfolded diagram of the fixing device; Figure 6 This is a schematic diagram of the overall structure after the fixing device is deployed. Detailed Implementation

[0018] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0019] Please see Figure 1 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0020] This invention provides a device and method for co-driven borehole protection using deep-hole spiral screen pipes in underground coal mines, such as... Figures 1 to 6 As shown.

[0021] A deep-hole spiral screen tube co-driven borehole protection device for coal mines includes a drilling rig 1, a hollow drill rod 2, an openable and closable drill bit 3 connected to the end of the hollow drill rod 2, and a pushing device 4 disposed at the rear end of the hollow drill rod 2, and the pushing device 4 is fixed on the drilling rig 1; the pushing device 4 is configured as a sealed cavity, and a first through hole 41 and a second through hole 42 are coaxially arranged on both sides of the sealed cavity, and a third through hole 43 for introducing high-pressure medium into the sealed cavity is also opened at its top; the third through hole 43 is used to connect a high-pressure medium source 7 to input high-pressure medium into the cavity to generate axial thrust.

[0022] The front end of the first through hole 41 is provided with an extension section that is threadedly connected to the hollow drill rod and rotates with the sealed cavity through the provided bearing assembly; a spiral screen tube 5 with spiral blades 51 on the outer wall is also provided in the hollow drill rod 2. The spiral blades 51 and the hollow drill rod 2 are in annular clearance fit. In this embodiment, the spiral blades 51 rotate counterclockwise, and the spiral screen tube 5 passes through the second through hole 42 and the first through hole 41 and is sent into the hollow drill rod 2.

[0023] Both the first through hole 41 and the second through hole 42 are equipped with sealing sleeves for sealing. The first through hole 41 is sealed by a sleeved rotary sealing assembly 44, which can rotate synchronously with the hollow drill rod 2 and has pressure holding capability. The second through hole 42 is sealed by a lip-shaped sealing sleeve 45, which can be made of wear-resistant rubber and is adapted to the outer circle of the spiral screen tube 5 to form a sliding sealing pair to ensure that the high-pressure medium does not leak. The second through hole 42 is used for the spiral screen tube to pass through, and the length of the lip-shaped sealing sleeve 45 in the cavity can reach the first through hole 41, so as to ensure that the high-pressure water / gas in the pushing device 4 will not leak through the extraction hole on the screen tube.

[0024] The first end of the spiral screen tube 5 is also equipped with a fixing device 6, which includes a connector 61, a push rod 64 movably inserted into the front end of the connector, and a rotatably arranged limiting claw 63. The front end of the push rod is a cam structure that presses against the limiting claw and, under the action of external force, pushes down to drive the limiting claw to rotate and unfold. The rear end of the push rod, located behind the limiting claw, is also equipped with a limiting baffle and a pressing spring 62. The pressing spring 62 is limited to the rear side of the limiting baffle 65 and moves with the push rod 64. Preferably, there are multiple limiting claws 63, and the maximum outer diameter after opening is larger than the diameter of the drill hole. The surface of the limiting claw 63 is also equipped with barbed anti-slip teeth. In this embodiment, the limiting claw 61 is provided with 3 to 4 65Mn steel claws, which naturally fit against the outer wall of the screen tube and open radially after being subjected to reaction force. The maximum opening angle is 60° to 90°, and the maximum outer diameter after opening is 5 to 10 mm larger than the diameter of the drill hole. The surface of the steel claw is provided with barbed anti-slip teeth with a tooth spacing of 3 to 5 mm, a tooth height of 1 to 2 mm, and a biting depth ≥ 5 mm.

[0025] The spiral blade 51 has a trapezoidal cross-section, and the angle between the side of the spiral blade and the axis of the spiral screen tube is 85°~89°. The spiral screen tube 5 has extraction holes located at the bottom of the grooves between the spiral blades, with a diameter of 2~4mm. The axis of the extraction hole forms a 15° angle with the normal to the tube wall. Adjacent holes are staggered and evenly distributed along the axial direction of the spiral grooves, with a hole spacing of 100-300mm. The spiral screen tube has matching internal / external threads at both ends for connecting adjacent screen tubes. To facilitate connection, the extraction holes avoid the threaded connection area at the end of the spiral screen tube 5, are ≥50mm away from the threaded end, and the openings are rounded with a radius of 0.5~1mm to reduce the risk of coal and rock fragments blocking the connection.

[0026] A method for a deep-hole spiral screen tube co-driven borehole protection device in coal mines includes the following steps: (1) Using the drilling rig 1 and the drill bit 3 connected to the drilling tool, drill the hole to the designed hole depth, and then remove the drill bit after cleaning the hole. (2) A rotary sealing assembly is installed in the first through hole 41, and the end section of the hollow rotating rod 2 is threadedly connected to the first through hole of the pushing device 4, so that the hollow drill rod and the first through hole can rotate synchronously and dynamically seal. (3) The first section of the spiral screen tube 5 is fed into the hollow drill rod through the second through hole and the high pressure medium is introduced into the pushing device through the third through hole of the pushing device. The high pressure medium enters the hollow drill rod and generates an axial force at the spiral blade on the outside of the spiral screen tube, pushing the spiral screen tube into the hole. (4) When the outer side of the first section of the spiral screen tube 5 is exposed for 30cm~50cm, a new spiral screen tube segment is connected and connected by the thread at the end. The hollow drill rod is driven to rotate and generate axial force with the spiral blades on the outside of the spiral screen tube. The spiral screen tube is then driven into the hole in conjunction with the high-pressure medium. All connections between screen tubes are forward rotational connections, while the outer thread of the screen tube rotates counterclockwise, driving the drill rod to rotate forward to prevent the screen tube connection from breaking due to the rotation of the drill rod. (5) Repeat step (4) and connect multiple spiral screen tubes in sequence until the spiral screen tube is lowered to the bottom of the hole. The spiral screen tube passes through the openable drill bit by axial force, and the fixing device at the first end of the spiral screen tube is pushed by the top rod to unfold the limiting claw and insert it into the coal seam hole wall 8 under the action of the bottom reaction force, thereby fixing the spiral screen tube to remain in the hole. (6) After the spiral screen tube 5 is lowered, drive the hollow drill rod 2 to rotate in the forward direction, and slowly withdraw the hollow drill rod 2 and the openable drill bit 3 connected to the end of the hollow drill rod, leaving the spiral screen tube 5 in the hole.

[0027] The following detailed description, in conjunction with specific embodiments, further illustrates the point: For underground coal mine environments with complex geological conditions, soft and broken coal seams, and high gas content, the deep-hole spiral screen tube collaborative drive hole protection technology of this invention can be used for gas drainage drilling hole protection operations.

[0028] During construction, drilling rig 1 and hollow drill rod 2 are used. A closable drill bit 3 is connected to the end of drill rod 2, and the borehole is drilled to the designed depth of 400 meters according to the design parameters. After drilling is completed, the borehole is washed with 10MPa high-pressure water for 20 minutes to remove rock powder from the borehole. After washing, drill rod 2 is kept in place and the drill is not withdrawn.

[0029] The external thread of the first through hole 41 of the pushing device 4 is screwed into the internal thread of the tail end of the drill rod 2. The independent rotation of the relative sealed cavity is achieved through a high-precision bearing assembly. After the connection is completed, the sealing performance needs to be verified by introducing a 0.6MPa high-pressure medium and holding it for 7 minutes. A pressure drop ≤0.08MPa is considered qualified.

[0030] The first section of the spiral screen tube 5, with spiral blades 51 on its outer wall, is inserted into the drill rod 2 through the second through hole 42 of the pushing device 4. The outer diameter of the spiral blades 51 is smaller than the inner diameter of the drill rod 2 to form an annular gap. The pushing device 4 is turned on, and high-pressure water / air is introduced into the drill rod 2 through the high-pressure medium source 7 connected to the third through hole 43. The high-pressure water / air flows along the annular gap, forming an axial thrust with the help of the spiral blades 51.

[0031] When 0.4m of the first spiral screen tube 5 remains exposed above the pushing device 4, turn off the high-pressure water / air input and secure the subsequent spiral screen tube 5 using a threaded connection. Re-enable the high-pressure water / air and control the drill rig 1 to drive the drill rod 2 to rotate in the opposite direction to the spiral screen tube 5. Utilize the friction between the inner wall of the drill rod 2 and the spiral blades 51 to generate auxiliary driving force, which, together with the high-pressure air thrust, propels the spiral screen tube 5 downwards. After each extension of the spiral screen tube 5, tighten the internal thread connection using a high-precision torque wrench. After threading, conduct a pressure test using 0.35MPa high-pressure medium. Hold the pressure for 4 minutes without leakage before continuing the descent. Repeat the extension and driving steps until the front end of the spiral screen tube 5 is approximately 0.7m from the bottom of the hole.

[0032] When the spiral screen tube 5 reaches the bottom of the drill rod 2, keep the drill rig 1 rotating forward and slowly retract the drill rod 2200mm. Utilize the axial force at the front end of the spiral screen tube 5 to trigger the openable drill bit 3 to switch from the closed state to the open state. The inner diameter of the openable drill bit 3 is larger than the outer diameter of the spiral screen tube 5. Continue pushing the spiral screen tube 5, allowing it to pass through the openable drill bit 3 and reach the bottom of the hole. At this time, the fixing device 6 at the end of the spiral screen tube 5 automatically opens and anchors under the reaction force from the bottom of the hole. The fixing device 6 contains four 65Mn steel claws, which naturally fit against the outer wall of the spiral screen tube 5. After being subjected to the reaction force, they open radially to a maximum angle of 75°. After opening, the maximum outer diameter is 7mm larger than the borehole diameter. The surface of the steel claws is provided with barbed anti-slip teeth with a tooth spacing of 4mm, a tooth height of 1.5mm, and a biting depth of 7mm. Control the drill rig 1 to rotate forward at a speed of 5r / min and simultaneously retract the drill rod 2 to ensure that the spiral screen tube 5 is smoothly placed inside the borehole to form a protective structure.

[0033] The use of the underground deep-hole spiral screen pipe collaborative drive hole protection device in this coal mine can theoretically achieve the lowering of the spiral screen pipe 5 for the entire section of a 400-meter deep hole. This helps to reduce the collapse rate of the hole wall, reduce the blockage of the extraction hole 52, improve the stability of gas extraction concentration, and extend the drilling service cycle, thereby ensuring the safe production and efficient operation of the coal mine.

[0034] If this patent uses terms such as "first" and "second" to define components, those skilled in the art should know that the use of "first" and "second" is merely for the convenience of describing the invention and simplifying the description, and the above terms have no special meaning.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0036] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify 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 limiting the scope of protection of this invention.

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A deep-hole spiral screen tube co-driven hole protection device for coal mines, characterized in that: It includes a drilling rig, a hollow drill rod, an openable and closable drill bit connected to the end of the hollow drill rod, and a pushing device disposed at the rear end of the hollow drill rod, wherein the pushing device is fixed on the drilling rig. The pushing device is configured as a sealed cavity, and a first through hole and a second through hole are coaxially arranged on both sides of the sealed cavity. A third through hole for introducing high pressure medium into the sealed cavity is also opened at the top. The front end of the first through hole is provided with an extension section that is threadedly connected to the hollow drill rod and rotates with the sealed cavity through the provided bearing assembly. The hollow drill rod is also fitted with a spiral screen tube with spiral blades on the outer wall. The spiral blades are in annular clearance fit with the hollow drill rod, and the spiral screen tube is fed into the hollow drill rod through the second through hole and the first through hole.

2. The deep-hole spiral screen tube co-driven hole protection device in coal mines according to claim 1, characterized in that: Both the first and second through holes are equipped with sealing sleeves for sealing.

3. The deep-hole spiral screen tube co-driven hole protection device in coal mines according to claim 1, characterized in that: The first through hole is sealed by a sleeved rotary sealing assembly, and the second through hole is sealed by a fitted lip-shaped sealing sleeve.

4. The deep-hole spiral screen tube co-driven hole protection device in coal mines according to claim 1, characterized in that: The first end of the spiral screen tube is also equipped with a fixing device, which includes a connector, a push rod movably inserted into the front end of the connector, and a rotatably arranged limiting claw. The front end of the push rod is configured as a cam structure that presses against the limiting claw and is pressed down under external force to drive the limiting claw to rotate and unfold. The rear end of the push rod located behind the limiting claw is also equipped with a limiting baffle and a pressing spring. The pressing spring is limited to the rear side of the limiting baffle and moves with the push rod.

5. A deep-hole spiral screen tube co-driven hole protection device for coal mines according to claim 4, characterized in that: The limiting claw is provided in multiple parts, and its maximum outer diameter after opening is larger than the diameter of the drill hole. The surface of the limiting claw is also provided with barbed anti-slip teeth.

6. The deep-hole spiral screen tube co-driven hole protection device in coal mines according to claim 4, characterized in that: The cross-section of the spiral blade is trapezoidal, and the angle between the side of the spiral blade and the axis of the spiral screen tube is 85°~89°.

7. A deep-hole spiral screen tube co-driven hole protection device for coal mines according to claim 4, characterized in that: The spiral screen tube has extraction holes, which are located at the bottom of the groove between the spiral blades, and the hole diameter is 2~4mm.

8. A deep-hole spiral screen tube co-driven hole protection device for coal mines according to claim 4, characterized in that: The ends of the spiral screen tubes are provided with matching internal / external threads for connecting the screen tubes.

9. A method for a deep-hole spiral screen tube co-driven borehole protection device in a coal mine according to any one of claims 4 to 8, characterized in that, Includes the following steps: (1) Use the drilling rig and drilling tools to connect the openable and closable drill bit to drill to the designed hole depth, and withdraw the drill after cleaning the hole; (2) A rotary sealing assembly is installed in the first through hole, and the end section of the hollow rotating rod is threadedly connected to the first through hole of the pushing device, so that the hollow drill rod and the first through hole can rotate synchronously and dynamically seal. (3) The first section of the spiral screen tube is fed into the hollow drill rod through the second through hole and the high pressure medium is introduced into the pushing device through the third through hole of the pushing device. The high pressure medium enters the hollow drill rod and generates an axial force at the spiral blade on the outside of the spiral screen tube, pushing the spiral screen tube into the hole. (4) When the outer side of the first section of the spiral screen tube is exposed for 30cm to 50cm, a new spiral screen tube segment is connected, and the hollow drill rod is driven to rotate to generate axial force with the spiral blades on the outer side of the spiral screen tube. The spiral screen tube is then driven into the hole in conjunction with the high-pressure medium. (5) Repeat step (4) and connect multiple sections of spiral screen tube in sequence until the spiral screen tube is lowered to the bottom of the hole. The spiral screen tube passes through the openable and closable drill bit by axial force, and the fixing device at the first end of the spiral screen tube is pushed by the top rod to unfold the limiting claw and insert it into the hole wall under the action of the reaction force at the bottom of the hole, thereby fixing the spiral screen tube to remain in the hole. (6) After the spiral screen tube is lowered, drive the hollow drill rod to rotate in the forward direction and slowly withdraw the hollow drill rod and the openable drill bit connected to the end of the hollow drill rod.

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