Liftable variable-diameter self-protecting wall bored pile drill bit and drilling method

Abstract

The present invention relates to the field of construction engineering technology, specifically to a lifting type variable diameter self-protection wall drilling bored pile drill bit and a drilling method. It comprises a main drill component, a drill bit is provided at the lower end of the main drill component, and the outer wall of the main drill component is sleeved with a wall protection outer cylinder; a lifting oil cylinder is provided on the main drill component to connect the wall protection outer cylinder; slots are distributed on the wall protection outer cylinder, and blades are provided in the slots; a pusher for controlling the opening and closing of the blades is provided on the main drill component; a knife edge is provided on one side of the blade, and a slurry outlet hole for outputting concrete slurry and a liquid outlet hole for outputting quick-setting agent are provided on the other side; a mud inlet hole is provided at the lower end of the main drill component, and a mud suction pipe is provided inside to communicate with the mud inlet hole. The present invention can realize the self-protection of cement-mixed soil, and at the same time of drilling, cement slurry and quick-setting agent can be injected into the wall protection layer to stir and quickly form a cement-mixed soil wall.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, in particular to a lifting variable-diameter self-protecting wall hole-forming cast-in-place pile drill bit and a drilling method. Background Art

[0002] A cast-in-place pile is a pile that is made by forming a pile hole in the foundation soil at the construction site through mechanical drilling, steel pipe squeezing or manual excavation, and then placing a steel cage inside and pouring concrete. Depending on the hole-forming method, cast-in-place piles can be divided into several categories, such as sunken pipe cast-in-place piles, bored cast-in-place piles and excavated cast-in-place piles.

[0003] There are two types of bored piles: manual bored piles and mechanical bored piles.

[0004] 1. Manual bored cast-in-place piles use manual excavation and reinforced concrete wall protection. They require less equipment and can be poured simultaneously after drilling in a large area, reducing on-site cross-operation and lowering the cost of pouring equipment. The pile bottom is thoroughly cleaned, visible and controllable, the pile quality is high and stable, the cost is higher but controllable, and the bearing capacity of single piles with the same cross-section is high.

[0005] However, artificial piles are currently being phased out because they require workers to go down into the well, the labor intensity is high, the safety risks for workers underground are great, the pile depth generally cannot exceed 16 meters, and they also require a large number of people, slow progress, difficult to organize workers, and high cost of wall protection materials.

[0006] 2. Most mechanical bored piles currently use rotary drilling and mechanical impact drilling methods.

[0007] The advantages of rotary bored cast-in-place piles are that they use steel casing or mud wall protection, which requires fewer operators, low labor intensity, fast progress in single strata, lower operating costs than manual piles, and no underground operation risks. There is no limit on the depth of piles. The disadvantages are: rotary bored piles are expensive because more equipment is needed for wall protection in complex strata, and the bottom of the pile cannot be thoroughly cleaned, there is sediment, and the quality of the hole is unstable. The bearing capacity of a single pile with the same cross-section is lower than that of a manual pile, and there is a lot of waste of concrete in complex strata. The cost is uncontrollable and sometimes even far exceeds that of manual piles.

[0008] Impact bored cast-in-place piles use impact drilling and mud wall protection to adapt to complex strata. The labor intensity of workers is low, but the progress of impact pile construction is very slow, the cost is high, the damage to the site is great, and the pile quality is average. Summary of the Invention

[0009] In response to the above problems, the present invention provides a lifting variable-diameter self-protecting wall bored pile drill bit, which can realize self-protection of cement-mixed soil walls. While drilling, cement slurry and quick-setting agent can be injected into the wall layer to quickly form a cement-mixed soil wall.

[0010] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a lifting type variable-diameter self-protecting wall hole-forming bored pile drill bit, comprising a main drill component, a drill bit is provided at the lower end of the main drill component, and the outer wall of the main drill component is sleeved with a protective wall outer tube; a lifting cylinder is provided on the main drill component to connect the protective wall outer tube; notches are distributed on the protective wall outer tube, and vertically flippable blades are provided in the notches; a pusher is provided on the main drill component for controlling the opening and closing of the blades; a cutting edge is provided on one side of the blade, and a slurry outlet hole for outputting concrete slurry and a liquid outlet hole for outputting quick-setting agent are provided on the other side; a mud inlet hole is provided at the lower end of the main drill component, and a mud suction pipe is provided inside to communicate with the mud inlet hole.

[0011] The beneficial effects of the above technical solution are: the outer wall protection tube rotates synchronously with the main drill component, so that the inner wall of the hole can be grouted by using the outer wall protection tube while drilling, and the concrete slurry is quickly mixed with the quick-setting agent and soil to form the inner wall of the concrete. The blades of the outer wall protection tube can not only expand the hole, but also mix the soil generated by the expansion with the concrete at the same time, thereby achieving the synchronous completion of the concrete wall protection.

[0012] As a further improvement of the above technical solution, the blades are distributed on the outer wall protection cylinder in a spiral shape.

[0013] The beneficial effects of the above improvements are: the spiral blade distribution can enable the outer tube of the wall protection to have the function of automatic drilling during the rotation process, and at the same time, the soil crushed by the blades can rise with the movement of the spiral blades, preventing the soil from falling and accumulating, and at the same time allowing the soil to be evenly mixed with the concrete slurry to ensure the quality of the wall protection.

[0014] As a further improvement of the above technical solution, the other end of the slurry outlet is connected to the grouting pipe; the other end of the liquid outlet is connected to the liquid injection pipe.

[0015] The beneficial effects of the above improvements are: the grouting pipe is connected to the concrete slurry delivery source, and the liquid injection pipe is connected to the quick-setting agent delivery source. The grouting pipe and the liquid injection pipe adopt a flexible and bendable structure to facilitate the opening and closing of the blades.

[0016] As a further improvement of the above technical solution, a slide groove is provided in the blade; a clamping groove is provided on the inner wall of the blade; the clamping groove is connected to the slide groove; a push head is provided at the end of the push piece; and the push head is slidably provided in the slide groove.

[0017] The beneficial effects of the above improvements are: when the pusher rises, the pusher head pushes the blades to open, and when the pusher descends, the pusher head pulls the blades to close; the pusher can not only be used to control the opening and closing of the blades, but also can scrape off the dirt on the inner wall of the blade during the up and down movement to control the closing of the blades, thereby preventing the blades from being unable to close due to the accumulation of dirt on the inner wall of the blades.

[0018] As a further improvement of the above technical solution, the main drill component is a hollow structure with a cavity formed inside.

[0019] The beneficial effect of the above improvement is that the cavity inside the main drill component can collect the mud generated by the main drill component drilling through the mud inlet hole, and then facilitate the mud suction pipe to suck and discharge it.

[0020] As a further improvement of the above technical solution, vertical grooves are distributed on the side walls of the main drill component; convex parts are distributed on the inner wall of the outer wall of the protective wall tube; and the convex parts are slidably arranged in the corresponding grooves.

[0021] The beneficial effect of the above improvement is that the convex part slides up and down in the groove, which can ensure that the wall protection outer tube can move up and down, and at the same time ensure that the wall protection outer tube can rotate synchronously with the main drill component, thereby improving the stability of the active connection between the wall protection outer tube and the main drill component.

[0022] As a further improvement of the above technical solution, a rotary joint is provided at the upper end of the main drill component; the mud suction pipe and the grouting pipe are connected to the rotary joint.

[0023] As a further improvement of the above technical solution, a water outlet hole is provided on the drill bit; the other end of the water outlet hole is connected to the water inlet pipe in the main drill component.

[0024] The beneficial effect of the above improvement is that the water inlet pipe injects water into the drill bit and comes out from the water outlet, which can not only cool the drill bit, but also moisten the soil, improve drilling efficiency, and make the soil broken by drilling contain sufficient moisture, which is convenient for the mud suction pipe to absorb and discharge.

[0025] As a further improvement of the above technical solution, the blades are distributed at the lower end of the outer wall protection tube; and the outer wall of the upper end of the outer wall protection tube is a smooth surface.

[0026] The beneficial effect of the above improvement is that after the blades are distributed at the lower end of the outer tube of the protective wall, the blades can be used to expand the hole and form the protective wall. At the same time, the smooth wall surface at the upper end can also be used to flatten the newly formed concrete inner wall, thereby improving the quality of the protective wall formation.

[0027] A method for drilling a hole using a lifting variable-diameter self-protecting wall bored pile drill bit comprises the following steps:

[0028] Diameter-changing operation: According to the diameter of the bored pile hole, the lifting cylinder is controlled to move up and down, so that the outer tube of the wall protection tube descends, driving the blades to open at the set angle;

[0029] Drilling operation: The main drill component and the outer tube of the retaining wall are driven to rotate synchronously to drill downwards. During the drilling process, the main drill component sucks away the mud generated by drilling through the mud suction pipe; the opened blades scrape and crush the mud on the hole wall. At the same time, the grouting pipe inputs concrete slurry into the blades, which is sprayed out from the slurry outlet, mixed evenly with the crushed mud, and then solidified to form a concrete retaining wall;

[0030] Withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the oil cylinder controls the outer tube of the retaining wall to rise, so that the blades are closed; then the drill bit rises as a whole to withdraw from the grouting hole, forming a grouting pile hole with a concrete retaining wall.

[0031] As a preferred method of the above method, a method for drilling a hole using a lifting variable-diameter self-protecting wall bored pile drill bit comprises the following steps:

[0032] Diameter-changing operation: According to the diameter of the bored pile hole, the lifting cylinder is controlled to move up and down, so that the outer tube of the wall protection tube descends, driving the blades to open at the set angle;

[0033] Drilling operation: The main drill component and the outer tube of the retaining wall are driven to rotate synchronously to drill downward. During the drilling process, the main drill component sucks away the soil generated by drilling through the mud suction pipe; the opened blades scrape and crush the soil on the hole wall, while the grouting pipe inputs concrete slurry into the blades and sprays it out from the slurry outlet hole. The liquid injection pipe inputs accelerator into the blades and sprays it out from the liquid outlet hole. The concrete slurry and accelerator are evenly mixed with the crushed soil and then solidify to form a concrete retaining wall;

[0034] Withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the oil cylinder controls the outer tube of the retaining wall to rise, so that the blades are closed; then the drill bit rises as a whole to withdraw from the grouting hole, forming a grouting pile hole with a concrete retaining wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the external structure of the drill bit of the present invention;

[0036] Figure 2 It is a schematic cross-sectional view of the drill bit of the present invention with its blades spread out;

[0037] Figure 3 It is a cross-sectional structural diagram of the drill bit with retracted blades according to the present invention;

[0038] Figure 4 It is a structural diagram of the blade folding;

[0039] Figure 5 It is a structural diagram of the blade opening;

[0040] Figure 6 Schematic diagram of the back structure of the blade;

[0041] Figure 7 Schematic diagram of the inner wall structure of the blade;

[0042] Figure 8 This is a top view of the internal structure of the rotary joint.

[0043] In the figure: 1. Main drill component; 2. Drill bit; 3. Mud inlet hole; 4. Main shaft; 5. Wall protection outer tube; 6. Protrusion; 7. Groove; 8. Lifting cylinder; 9. Blade; 10. Notch; 11. Water inlet pipe; 12. Mud suction pipe; 13. Grouting pipe; 14. Liquid injection pipe; 15. Oil pipe; 16. Rotary joint; 17. Pusher; 18. Pusher head; 19. Cavity; 91. Slide; 92. Slot; 93. Blade; 94. Mud outlet hole; 95. Liquid outlet hole; 96. Grouting port; 97. Liquid injection port. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0045] See also Figures 1 to 8 In a specific embodiment, a lifting variable-diameter self-protecting wall bored pile drill bit includes a main drill component 1, a drill bit 2 is provided at the lower end of the main drill component 1, and the outer wall of the main drill component 1 is sleeved with a protective wall outer tube 5; a lifting cylinder 8 is provided on the main drill component 1 to connect with the protective wall outer tube 5; slots 10 are distributed on the protective wall outer tube 5, and vertically flippable blades 9 are provided in the slots 10; a pusher 17 for controlling the opening and closing of the blades 9 is provided on the main drill component 1; a cutting edge 93 is provided on one side of the blade 9, and a slurry outlet hole 94 for outputting concrete slurry and a liquid outlet hole 95 for outputting accelerator are provided on the other side; a mud inlet hole 3 is provided at the lower end of the main drill component 1, and a mud suction pipe 12 is provided inside to communicate with the mud inlet hole 3.

[0046] The main drill component 1 is hollow cylindrical, with a main shaft 4 provided at the center of the top, a mud inlet hole 3 at the bottom, and various conveying pipelines such as a mud suction pipe 12 installed inside. The conveying pipelines are installed in contact with the inner wall of the main drill component 1. In order to prevent the soil from squeezing and damaging these pipelines, the side wall of the main drill component 1 can be set to a double-wall structure, so that the various conveying pipelines are in the interlayer cavity of the double wall and isolated from the inner cavity of the main drill component 1.

[0047] A rotary joint 16 is provided at the upper end of the main drill component 1, and the mud suction pipe 12 is connected to the rotary joint 16; the mud suction pipe 12 moves synchronously with the rotation of the main drill component 1, and the rotary joint 16 is connected to the external pipeline; the external pipeline will not move with the rotation of the main drill component 1.

[0048] The quick-setting agent is a special quick-setting agent for concrete. After the cement slurry and the quick-setting agent are sprayed out from the blade 9 and mixed with the soil, the initial setting can be completed within 10 seconds and a certain strength can be reached within 45 seconds; the cement slurry that originally took 45 minutes to form initial setting can form initial setting within a short period of time.

[0049] The blade 93 is sharp and is used to scrape the inner wall of the bored pile hole, scrape off the soil and crush it.

[0050] The slurry outlet hole 94 , the liquid outlet hole 95 and the blade edge 93 are respectively located on different sides of the blade, which can prevent mud from blocking the slurry outlet hole 94 and the liquid outlet hole 95 .

[0051] The mud suction pipe 12 can be directly connected to the mud inlet hole 3 to facilitate sucking mud, or it can be indirectly connected. The mud inlet hole 3 guides the mud into the cavity of the main drill component 1, and then the mud suction pipe 12 sucks the mud in the cavity.

[0052] like Figure 1 As shown, based on the above embodiment, it is further optimized: the blades 9 are distributed in a spiral shape on the outer wall protection cylinder 5. The slots 10 are distributed in a spiral shape on the outer wall protection cylinder 5, and then the blades 9 are installed in the slots 10; when the drill bit rotates, the spiral line of the blades rotates in the same direction as the drill bit.

[0053] like Figure 2 As shown, based on the above embodiment, the other end of the slurry outlet 94 is connected to the grouting pipe 13; the other end of the liquid outlet 95 is connected to the liquid injection pipe 14. The upper ends of the grouting pipe 13 and the liquid injection pipe 14 are also connected to the rotary joint 16, and the other end of the rotary joint 16 is connected to the corresponding delivery pipeline.

[0054] like Figure 4-5 As shown, based on the above embodiment, it is further optimized: a slide groove 91 is provided in the blade 9; a clamping groove 92 is provided on the inner wall of the blade 9; the clamping groove 92 is connected to the slide groove 91; a pusher head 18 is provided at the end of the pusher 17; the pusher head 18 is slidably provided in the slide groove 91. The width of the clamping groove 92 is smaller than the width of the slide groove 91; the pusher head 18 can be a spherical body that is clamped and slides in the slide groove 91; the pusher head 18 can also be a roller that rolls in the slide groove 91; the pusher 17 is a rod-shaped structure with a diameter smaller than the width of the pusher head 18 and also smaller than the width of the clamping groove 92. The clamping groove 92 and the slide groove 91 can pass through the upper and lower end surfaces of the blade 9.

[0055] like Figure 2 As shown, based on the above embodiment, the main drill component 1 is further optimized: the main drill component 1 is a hollow structure, forming a cavity 19 inside. The main drill component 1 is provided with a base plate at the bottom, and the drill bits 2 are mounted side by side on the base plate. The base plate has an opening to form a mud inlet 3. The cavity 19 is used to reduce the weight of the main drill component 1 and also to collect crushed mud.

[0056] like Figure 2-3 As shown, based on the above embodiment, the embodiment is further optimized: the side wall of the main drill component 1 is provided with vertical grooves 7, which are evenly distributed in an annular shape; the inner wall of the outer wall protection tube 5 is provided with protrusions 6; the protrusions 6 are slidably disposed in the corresponding grooves 7. The grooves 7 are located on the upper side wall of the main drill component 1; the protrusions 6 are convex strip structures, located at the upper end of the inner wall of the outer wall protection tube 5.

[0057] like Figure 2 、 8 As shown, based on the above embodiment, it is further optimized: the upper end of the main drill component 1 is provided with a rotary joint 16; Figure 8 What is shown is a top view of the internal structure of the upper disc or the lower disc; the rotary joint 16 is disc-shaped, including an upper disc and a lower disc. When the upper disc and the lower disc are closed, there are multiple layers of mutually isolated cavities distributed in an annular shape inside, and interfaces are provided at the bottom of the cavities to be connected to corresponding pipes respectively; the upper disc and the lower disc can rotate with each other; the lower disc is fixedly connected to the main drill component 1, and rotates as the main drill component 1 rotates, and the interfaces on the upper disc are connected to the corresponding pipes and remain fixed; the pipe connected to the upper disc transports the material into the annular cavity, and then transports it out from the pipe at the interface of the lower disc.

[0058] Based on the above embodiment, the present invention is further optimized: a water outlet is provided on the drill bit 2; the other end of the water outlet is connected to the water inlet pipe 11 in the main drill component 1. Since the water outlet is provided on the drill bit 2, it is not described in detail here.

[0059] like Figure 1 As shown, based on the above embodiment, the blades 9 are further optimized: the blades 9 are distributed at the lower end of the outer wall protection tube 5; the outer wall of the upper end of the outer wall protection tube 5 is smooth. The blades 9 remain distributed at the lower end of the outer wall protection tube 5, while the upper end of the outer wall protection tube 5 remains smooth and unbroken. The upper end outer wall can play a role in smoothing the formed concrete wall.

[0060] A method for radial drilling of cast-in-place piles using a liftable variable-diameter self-protecting wall drilling drill bit comprises the following steps:

[0061] Diameter-changing operation: According to the diameter of the bored pile hole, the lifting cylinder 8 is controlled to move up and down, so that the outer tube 5 of the wall protection is lowered, and the blades 9 are driven to open according to the set angle;

[0062] Drilling operation: The main drill component 1 and the outer tube 5 of the retaining wall are driven to rotate synchronously to drill downward. During the drilling process, the main drill component 1 sucks away the mud generated by drilling through the mud suction pipe 12; the opened blades 9 scrape and crush the mud on the hole wall. At the same time, the grouting pipe 13 inputs concrete slurry into the blades 9, which is sprayed out from the slurry outlet 94, mixed evenly with the crushed mud, and then solidified to form a concrete retaining wall;

[0063] Withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the oil cylinder controls the outer tube of the retaining wall to rise, so that the blades 9 are closed; then the drill bit rises as a whole to withdraw from the grouting hole, forming a grouting pile hole with a concrete retaining wall.

[0064] A method for radial drilling of cast-in-place piles using a liftable variable-diameter self-protecting wall drilling drill bit comprises the following steps:

[0065] Diameter-changing operation: According to the diameter of the bored pile hole, the lifting cylinder 8 is controlled to move up and down, so that the outer tube 5 of the wall protection is lowered, and the blades 9 are driven to open according to the set angle;

[0066] Drilling operation: The main drill component 1 and the outer tube 5 of the retaining wall are driven to rotate synchronously to drill downward. During the drilling process, the main drill component 1 sucks away the soil generated by drilling through the mud suction pipe 12; the opened blades 9 scrape and crush the soil on the hole wall. At the same time, the grouting pipe 13 inputs concrete slurry into the blades 9 and sprays it out from the slurry outlet 94. The liquid injection pipe 14 inputs the accelerator into the blades 9 and sprays it out from the liquid outlet 95. The concrete slurry and accelerator are evenly mixed with the crushed soil and then solidify to form a concrete retaining wall.

[0067] Withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the oil cylinder controls the outer tube of the retaining wall to rise, so that the blades 9 are closed; then the drill bit rises as a whole to withdraw from the grouting hole, forming a grouting pile hole with a concrete retaining wall.

[0068] The specific working principle of the present invention is:

[0069] The present invention utilizes a main drill component 1 to complete the main drilling work of the bored pile hole, utilizes the blades 9 of the outer tube 5 of the protective wall to expand the drill hole, and then simultaneously pours concrete slurry and accelerating setting agent into the inner wall of the bored pile hole. The blades 9 are used to synchronously mix the soil generated by the expansion with the concrete slurry and accelerating setting agent to form the protective wall of the bored pile hole, and the outer wall of the outer tube 5 is used to scrape the protective wall flat.

[0070] The technical solution of the present invention is compared with the artificial bored cast-in-place pile and the traditional rotary bored cast-in-place pile as follows:

[0071] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0072] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method of the present invention and its core ideas. The above is only a preferred implementation method of the present invention. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of the present invention.

Claims

1. A lifting type variable diameter self-protecting wall bored pile drill bit, comprising a main drill component (1), a drill bit (2) is provided at the lower end of the main drill component (1), characterized in that: The outer wall of the main drill component (1) is sheathed with a wall protection outer cylinder (5); a lifting oil cylinder (8) is provided on the main drill component (1) and connected to the wall protection outer cylinder (5); slots (10) are distributed on the wall protection outer cylinder (5), and vertically flippable blades (9) are provided in the slots (10); a pusher (17) for controlling the opening and closing of the blades (9) is provided on the main drill component (1); a knife edge (93) is provided on one side of the blade (9), and a slurry outlet hole (94) for outputting concrete slurry and a liquid outlet hole (95) for outputting quick-setting agent are provided on the other side; a mud inlet hole (3) is provided at the lower end of the main drill component (1), and a mud suction pipe (12) is provided inside to communicate with the mud inlet hole (3); A slide groove (91) is provided in the blade (9); a clamping groove (92) is provided on the inner wall of the blade (9); the clamping groove (92) is communicated with the slide groove (91); a push head (18) is provided at the end of the push member (17); the push head (18) is slidably provided in the slide groove (91); The main drill component (1) is a hollow structure, with a cavity (19) formed inside; A vertical groove (7) is distributed on the side wall of the main drill component (1); a convex portion (6) is distributed on the inner wall of the wall protection outer cylinder (5); and the convex portion (6) is slidably arranged in the corresponding groove (7).

2. The liftable variable diameter self-protecting wall bored pile drill bit according to claim 1, characterized in that: The blades (9) are distributed in a spiral shape on the wall protection outer cylinder (5).

3. The liftable variable diameter self-protecting wall bored pile drill bit according to claim 1, characterized in that: The other end of the slurry outlet hole (94) is in communication with the grouting pipe (13); the other end of the liquid outlet hole (95) is in communication with the liquid injection pipe (14).

4. The liftable variable diameter self-protecting wall bored pile drill bit according to claim 1, characterized in that: A rotary joint (16) is provided at the upper end of the main drill component (1); the mud suction pipe (12) and the grouting pipe (13) are connected to the rotary joint (16).

5. The liftable variable diameter self-protecting wall bored pile drill bit according to claim 1, characterized in that: The drill bit (2) is provided with a water outlet hole; the other end of the water outlet hole is connected to the water inlet pipe (11) in the main drill component (1).

6. A method for drilling a hole using the liftable variable diameter self-protecting wall bored pile drill bit according to claim 1, characterized in that: The steps include: Diameter-changing operation: according to the diameter of the bored pile hole, the lifting cylinder (8) is controlled to move up and down, so that the outer tube (5) of the wall protection is lowered, and the blades (9) are driven to open at a set angle; Drilling operation: the main drill component (1) and the outer tube (5) of the protective wall are driven to rotate synchronously and drill downwards. During the drilling process, the main drill component (1) sucks away the mud generated by the drilling through the mud suction pipe (12); the opened blades (9) scrape and crush the mud on the hole wall, and at the same time, the grouting pipe (13) inputs concrete slurry and quick-setting agent into the blades (9), sprays them out from the slurry outlet (94), mixes them evenly with the crushed mud, and then solidifies to form a concrete protective wall; Hole withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the lifting cylinder (8) controls the outer tube (5) of the retaining wall to rise, so that the blades (9) are closed; then the drill bit is lifted up as a whole and withdraws from the grouting hole, forming a grouting pile hole with a concrete retaining wall.

7. A method for drilling a hole using the liftable variable diameter self-protecting wall bored pile drill bit according to claim 3, characterized in that: The steps include: Diameter-changing operation: according to the diameter of the bored pile hole, the lifting cylinder (8) is controlled to move up and down, so that the outer tube (5) of the wall protection is lowered, and the blades (9) are driven to open at a set angle; Drilling operation: the main drill component (1) and the outer tube (5) of the retaining wall are driven to rotate synchronously and drill downwards. During the drilling process, the main drill component (1) sucks away the soil generated by the drilling through the mud suction pipe (12); the opened blades (9) scrape and crush the soil on the hole wall, and at the same time, the grouting pipe (13) inputs concrete slurry into the blades (9) and sprays it out from the slurry outlet hole (94); the liquid injection pipe (14) inputs the quick-setting agent into the blades (9) and sprays it out from the liquid outlet hole (95); the concrete slurry and the quick-setting agent are evenly mixed with the crushed soil and then solidify to form a concrete retaining wall; Hole withdrawal operation: After the drilling is completed, the injection of concrete slurry and quick-setting agent is stopped, and the oil cylinder controls the outer tube (5) of the retaining wall to rise, so that the blades (9) are closed; then the drill bit is lifted up as a whole and withdraws from the grouting hole, forming a grouting pile hole with a concrete retaining wall.

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