A pile foundation drill bit structure and drilling method thereof

Abstract

The present invention discloses a pile foundation drill bit structure, comprising an upper drill bit (8), the upper end of which is an upper drilling part providing upward assistance when the drill bit moves upward; and a lower drill bit (4), the upper end of which is coaxially connected to the lower end of the upper drill bit (8), and the lower end of which is a lower drilling part driving the drill bit to drill downward; wherein the drilling range W2 formed by the upper drilling part is less than or equal to the drilling range W1 formed by the lower drilling part. The drill bit itself can provide assistance when the drill bit exits the drilling, and the drilling operation can be smoothly carried out.

Description

Technical Field

[0001] The invention relates to a pile foundation drill bit structure and a drilling method thereof. Background Art

[0002] During the construction process, traditional drill bits will encounter resistance from different directions when passing through different geological layers. When the resistance is uneven, the drilling direction will be deviated, and the newly drilled hole wall area behind the drill bit will also shrink or expand in diameter, and in severe cases, the hole will collapse. If these problems are not handled, there will be deviations between the actual hole diameter and the designed hole diameter, and between the actual hole shape and the designed hole shape. In the least, the force of the pile foundation will not meet the design requirements, and in the worst, the hole will collapse and the pile will break when pouring concrete.

[0003] In order to overcome the above-mentioned situation, a technology has been adopted at this stage, and its corresponding application number is 201820308315.6. The patent name is a pile foundation drill bit for civil engineering. Its structure includes a first gear arranged on the top of the rotating drum, which can enable the extrusion plate to rotate around the outer wall of the rotating rod under the action of the motor. By arranging an extrusion plate above the transmission assembly, the extrusion plate can perform secondary cleaning and reinforcement of the hole wall, making the hole wall smoother, and effectively preventing problems such as hole wall shape, collapse and offset during concrete pouring. It mainly relies on the extrusion plate arranged on the upper part of the drill bit to support the soil around the hole drilled by the drill bit. Although the extrusion plate structure configured for the drill bit can support the soil and guide the drill bit to drill vertically, the extrusion plate structure occupies a large volume. As the drill bit enters the soil, the drill bit encounters great resistance, which may greatly affect the normal drilling operation of the drill bit. In addition, the most important thing is that when this type of pile foundation drill bit exits the hole after drilling, it only relies on external force to withdraw the drill rod from the hole. There is a hidden danger of an unsmooth exit process when the drill bit of this structure exits the hole, and there is room for improvement. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a pile foundation drill bit structure, in which the drill bit itself can provide assistance when the drill bit exits the drilling hole, so that the drill bit exiting the drilling operation can be carried out smoothly.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is: a pile foundation drill bit structure, comprising an upper drill bit, whose upper end is an upper drilling part that provides upward assistance when the drill bit moves upward; and a lower drill bit, whose upper end is coaxially connected to the lower end of the upper drill bit, and whose lower end is a lower drilling part that drives the drill bit to drill downward; wherein the drilling range W2 formed by the upper drilling part is less than or equal to the drilling range W1 formed by the lower drilling part.

[0006] Furthermore, it also includes a longitudinal telescopic structure, a first supporting structure and a second supporting structure; the longitudinal telescopic structure includes an extension section that can be extended downward and a main section that can be retracted to the extension section; the first supporting structure, the longitudinal telescopic structure and the second supporting structure are distributed in sequence from top to bottom between the lower end of the upper drill bit and the upper end of the lower drill bit; the lower end of the upper drill bit is coaxially connected to the upper end of the first supporting structure, the lower end of the first supporting structure is connected to the main section of the longitudinal telescopic structure, and the first supporting structure has at least two symmetrically arranged first soil support blocks on its circumference that are extended / retracted under the drive of a power mechanism inside the first supporting structure; the second supporting structure is connected between the extension section of the longitudinal telescopic structure and the upper end of the lower drill bit, and the second supporting structure has at least two symmetrically arranged second soil support blocks on its circumference that are extended / retracted under the drive of a power mechanism inside the second supporting structure; wherein the extension / retraction movement of the first soil support block and the extension / retraction movement of the second soil support block are asynchronous and reverse movements to each other.

[0007] Furthermore, the first supporting structure includes a first supporting structure shell and the power mechanism inside the first supporting structure shell; the circumferential side of the first supporting structure shell is provided with hollow areas that are distributed at intervals and have a shape that matches the first soil support block and a matching number; the first soil support block is installed in the first supporting structure shell, and each first soil support block is synchronously extended / retracted through a corresponding hollow area under the drive of the power mechanism inside the first supporting structure shell.

[0008] Furthermore, the first support structure shell is a square shell or a cylindrical shell, and its size is smaller than the size of the drilling range W1 formed by the lower drilling part of the lower drill bit; when the first support structure shell is a square shell, the number of first soil support blocks extending from opposite sides of the first support structure shell is the same, or the number of first soil support blocks extending from each of the four sides of the first support structure shell is the same; when the first support structure shell is a cylindrical shell, the first soil support blocks extending from the circumferential side of the first support structure shell are evenly arranged at equal angles.

[0009] Furthermore, the second supporting structure includes a second supporting structure shell and the power mechanism inside the second supporting structure shell; the circumferential side of the second supporting structure shell is provided with hollow areas which are spaced apart and have shapes that match the second soil support blocks and numbers that match; the second soil support blocks are installed in the second supporting structure shell, and every two second soil support blocks are synchronously extended / retracted through two corresponding hollow areas under the drive of the power mechanism inside the second supporting structure shell.

[0010] Furthermore, the second support structure shell is a square shell or a cylindrical shell, and its size is smaller than the size of the drilling range W1 formed by the lower drilling part of the lower drill bit; when the second support structure shell is a square shell, the number of second soil support blocks extending from the opposite sides of the second support structure shell is the same, or the number of second soil support blocks extending from each two of the four sides of the second support structure shell is the same; when the second support structure shell is a cylindrical shell, the second soil support blocks extending from the circumferential side of the second support structure shell are evenly arranged at equal angles.

[0011] Furthermore, a plurality of second drill bit drilling guide mechanisms are installed on the circumferential side of the upper end of the lower drill bit and are spaced apart along the length direction; the second drill bit drilling guide mechanism includes a second mounting frame installed on the lower drill bit, a rotatable second guide wheel is installed on the second mounting frame, and some or all of the second guide wheels are provided with spaced apart second soil cutting teeth along their rotation direction, the rotation tangent direction of the second guide wheel follows the drilling direction, and the second guide wheel does not protrude beyond the drilling range W1 formed by the lower drilling portion of the lower drill bit.

[0012] Furthermore, a plurality of first drill bit drilling guide mechanisms spaced apart along the length direction are installed on the peripheral side of the main section of the longitudinal telescopic structure; the first drill bit drilling guide mechanism includes a first mounting frame installed on the longitudinal telescopic structure, a rotatable first guide wheel is installed on the first mounting frame, some or all of the first guide wheels are provided with first soil cutting teeth spaced apart along their rotation direction, the rotation tangent direction of the first guide wheel follows the drilling direction, and the first guide wheel does not protrude beyond the drilling range W1 formed by the lower drilling portion of the lower drill bit.

[0013] Furthermore, a plurality of third drill bit drilling guide mechanisms are installed on the peripheral side of the lower end of the upper drill bit and are spaced apart along the length direction; the third drill bit drilling guide mechanism includes a third mounting frame installed on the upper drill bit, a rotatable third guide wheel is installed on the third mounting frame, and some or all of the third guide wheels are provided with spaced apart third soil cutting teeth along their rotation direction, the rotation tangent direction of the third guide wheel follows the drilling direction, and the third guide wheel does not protrude beyond the drilling range W1 formed by the lower drilling part of the lower drill bit.

[0014] Furthermore, the head of the lower drilling portion of the lower section drill bit has a spiral lower cutting blade located at the upper end of the lower cutting blade to form a plurality of circumferentially distributed lower cutting knives, and the head of the upper drilling portion has a spiral upper cutting blade located at the lower end of the upper cutting blade to form a plurality of circumferentially distributed upper cutting knives, and the upper cutting blade and the upper cutting knives are started when the drill bit is about to exit drilling, and their rotation direction is opposite to the rotation direction of the lower cutting blade and the lower cutting knives when drilling downward; the upper cutting knife of the upper drilling portion forms the drilling range W2, and the lower cutting knife of the lower drilling portion forms the drilling range W1.

[0015] Compared with the prior art, the above structural design has the following advantages:

[0016] The upper and lower sections of the drill bit design are adopted. The lower section of the drill bit is responsible for drilling downwards, and the upper drilling part of the upper section of the drill bit is responsible for providing assistance when the drill bit exits the drilling hole, so as to reduce the external force required to ensure that the drill bit exits the drilling hole smoothly. In addition, the drilling range W2 formed by the upper drilling part is less than or equal to the drilling range W1 formed by the lower drilling part. The purpose of this design is that when drilling downwards, the additional upper drilling part of the upper section of the drill bit will not increase the resistance of the drill bit to drilling downwards. Similarly, it will not increase the resistance encountered by the drill bit when exiting the drilling hole, which also ensures that the drill bit exits the drilling hole smoothly from an additional aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a planar structural schematic diagram of the overall structure of the present invention.

[0018] Figure 2 yes Figure 1 Schematic diagram of the plan structure of the next workstation during drilling.

[0019] Figure 3 yes Figure 2 Schematic diagram of the plan structure of the next workstation during drilling.

[0020] Figure 4 yes Figure 3 Schematic diagram of the plan structure of the next workstation during drilling.

[0021] Figure 5 It is a schematic diagram of the planar structure of a first supporting structure of a structural form of the present invention.

[0022] Figure 6 It is a schematic diagram of the planar structure of a first supporting structure of another structural form of the present invention.

[0023] Figure 7 It is a schematic diagram of the planar structure of a second supporting structure of a structural form of the present invention.

[0024] Figure 8It is a schematic diagram of the planar structure of a second supporting structure in another structural form of the present invention.

[0025] As shown in the figure: 1. longitudinal telescopic structure, 2. first supporting structure; 211. first soil supporting block; 212. first supporting structure shell; 3. second supporting structure; 311. second soil supporting block; 312. second supporting structure shell; 4. lower drill bit; 411. lower cutting blade; 412. lower cutting knife; 413. upper cutting blade; 414. upper cutting knife; 511. first mounting frame; 512. second mounting frame; 513. third mounting frame; 611. first guide wheel; 612. second guide wheel; 613. third guide wheel; 711. first soil cutting tooth; 712. second soil cutting tooth; 713. third soil cutting tooth; 8. upper drill bit; 9. upper top frame. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below through specific implementation examples in conjunction with the accompanying drawings.

[0027] The present invention proposes a new drill bit structure and a drilling method based on the background technology, which has the advantages that the drill bit itself can provide assistance when the drill bit exits the drilling hole, the drill bit exits the drilling operation and can be smoothly carried out, the drill bit is not easy to deviate, not easy to tilt, and the drilling resistance is small. The detailed structure is as follows:

[0028] Embodiment 1

[0029] Overall, see Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, the drill bit structure includes a longitudinal telescopic structure 1, a first supporting structure 2, a second supporting structure 3, a lower drill bit 4 and an upper drill bit 8.

[0030] The upper end of the upper drill bit 8 is an upper drilling part that provides an upward assist when the drill bit moves upward; the lower end of the lower drill bit 4 is a lower drilling part that drives the drill bit to drill downward; and between the lower end of the upper drill bit 8 and the upper end of the lower drill bit 4, a first supporting structure 2, a longitudinal telescopic structure 1 and a second supporting structure 3 are distributed from top to bottom in sequence; the longitudinal telescopic structure 1 includes an extension section that can be extended downward and a main body section that can be retracted to the extension section; and they are connected in the following manner: the lower end of the upper drill bit 8 is coaxially connected to the upper end of the first supporting structure 2, and the first The lower end of the supporting structure 2 is coaxially connected to the main section of the longitudinal telescopic structure 1, and the first supporting structure 2 has at least two symmetrically arranged first soil support blocks 211 on its circumferential side, which are extended / retracted under the drive of the power mechanism inside the first supporting structure 2; the second supporting structure 3 is connected between the extended section of the longitudinal telescopic structure 1 and the upper end of the lower drill bit 4, and the second supporting structure 3 has at least two symmetrically arranged second soil support blocks 311 on its circumferential side, which are extended / retracted under the drive of the power mechanism inside the second supporting structure 3.

[0031] Wherein, the drilling range W2 formed by the upper drilling portion is smaller than or equal to the drilling range W1 formed by the lower drilling portion.

[0032] To facilitate understanding of the drilling range W1 formed by the lower drilling portion and the drilling range W2 formed by the upper drilling portion, in this embodiment, the structures of the lower drill bit 4 and the upper drill bit 8 are first specifically introduced. The lower end of the lower drill bit 4 is the lower drilling portion. What is additionally highlighted is that the drilling portion of the drill bit structure is responsible for rotating drilling, and the remaining structure does not rotate. The head of the drilling portion has a spiral lower cutting blade 411. The upper end of the lower cutting blade 411 forms a multi-layer circumferentially distributed lower cutting knife 412. The drilling portion realizes drilling without specific expansion as it is a mature technology. In this embodiment, the length of the lower cutting knife 412 protruding from the lower drill bit 4 is basically consistent, so that the drilling portion of the lower drill bit 4 can drill a range W1. The drilling range W1 here can be understood as the hole of the drill. The head of the upper drilling part has a spiral upper cutting blade 413, and the lower end of the upper cutting blade 413 forms a multi-layer circumferentially distributed upper cutting knife 414, and the upper cutting blade 413 and the upper cutting knife 414 are started when the drill bit is about to exit the drilling, and the rotation direction of the upper cutting blade 411 and the lower cutting knife 412 is opposite to the rotation direction when the lower cutting blade 411 and the lower cutting knife 412 are drilling downward, and the rotation direction is opposite to the rotation direction of the lower cutting blade 411 and the lower cutting knife 412 when drilling downward, so as to provide an upward assist. In addition, the drilling range W2 formed by the upper drilling part is less than or equal to the drilling range W1 formed by the lower drilling part, indicating that the added upper drilling part enlarges the aperture of the drilling hole, so the resistance of the drill bit to drilling downward or exiting from the drilling hole is smaller.

[0033] According to the above, the longitudinal telescopic structure 1 includes an extension section that can be extended downward and a main section that can be retracted to the extension section. Its structure is essentially to install a cylinder body section of a cylinder in a hollow rod body, the rod body itself serves as the main section, and the piston rod of the cylinder serves as the extension section. Of course, the cylinder here can also be replaced by other pushing mechanisms. Of course, the rod body can be cancelled, and the cylinder body of the cylinder directly serves as the main section, and the piston rod of the cylinder serves as the extension section. Here, the main section retracts to the extension section by relying on its own gravity to move the main section downward and retract to the extension section after the oil cylinder is tilted. Or through external force, one way to understand the external force is that the drill rod connected to the longitudinal telescopic structure 1 gives it a downward force, forcing the main section to move downward and retract to the extension section.

[0034] A first supporting structure 2 is installed on the main section of the longitudinal telescopic structure 1, and the first supporting structure 2 has at least two symmetrically arranged first soil support blocks 211 on its circumferential side, which are extended / retracted under the drive of a power mechanism inside the first supporting structure 2; the following is a first supporting structure 2 with a specific structure, which can provide a more stable and uniform supporting force and improve the supporting effect. The first supporting structure 2 includes a first supporting structure shell 212 and a power mechanism inside the first supporting structure shell 212; the first supporting structure shell 212 is provided with hollow areas at intervals, which are consistent in shape and matched in number with the first soil support blocks 211; the first soil support blocks 211 are installed in the first supporting structure shell 212, and each first soil support block 211 is synchronously extended / retracted through a corresponding hollow area under the drive of the power mechanism inside the first supporting structure shell 212, see Figure 1 , Figure 2 , Figure 3 or Figure 4 Each first soil support block 211 should be equipped with a power mechanism, which is marked with B.

[0035] Of course, in the specific implementation, the shape of the first support structure shell 212 can be further limited, and different shapes can be flexibly selected according to the construction conditions. The following is a case where the first support structure shell 212 is a square shell or a cylindrical shell, of course, it is not limited to the following two shapes. The first support structure shell 212 is a square shell or a cylindrical shell, see Figure 5 and Figure 7As shown, and its size is smaller than the size of the drilling range W1 formed by the lower drilling portion of the lower drill bit 4; when the first supporting structure shell 212 is a square shell, the number of first soil support blocks 211 extending from the opposite sides of the first supporting structure shell 212 is the same, or the number of first soil support blocks 211 extending from each of the four sides of the first supporting structure shell 212 is the same; when the first supporting structure shell 212 is a cylindrical shell, the first soil support blocks 211 extending from the circumferential side of the first supporting structure shell 212 are evenly arranged at equal angles.

[0036] Correspondingly, according to the above, the upper end of the second support structure 3 is connected to the pushing end of the pushing mechanism. If the pushing mechanism is a cylinder, the upper end of the second support structure 3 is fixedly connected to the piston rod of the cylinder, and the circumferential side of the second support structure 3 also has at least two symmetrically arranged second soil support blocks 311 that are extended / retracted under the drive of the power mechanism inside the second support structure 3; the following is a second support structure 3 with a specific structure, which can provide a more stable and uniform supporting force and improve the supporting effect. The second support structure 3 includes a second support structure shell 312 and a power mechanism inside the second support structure shell 312; the circumferential side of the second support structure shell 312 is provided with hollow areas that are distributed at intervals and have a shape that matches the second soil support block 311 and a matching number; the second soil support block 311 is installed in the second support structure shell 312, and every second soil support block 311 is synchronously extended / retracted through two corresponding hollow areas under the drive of the power mechanism inside the second support structure shell 312, see Figure 1 , Figure 2 , Figure 3 or Figure 4 Each second soil support block 311 should be equipped with a power mechanism, which is marked with A.

[0037] Of course, in the specific implementation, the shape of the second support structure shell 312 can be further limited, and different shapes can be flexibly selected according to the construction conditions. The following is a case where the second support structure shell 312 is a square shell or a cylindrical shell. Figure 6 and Figure 8As shown, the second support structure shell 312 is a square shell or a cylindrical shell, and its size is smaller than the size of the drilling range W1 formed by the lower drilling part of the lower drill bit 4; when the second support structure shell 312 is a square shell, the number of second soil support blocks 311 extending from the opposite sides of the second support structure shell 312 is the same, or the number of second soil support blocks 311 extending from each two of the four sides of the second support structure shell 312 is the same; when the second support structure shell 312 is a cylindrical shell, the second soil support blocks 311 extending from the circumferential side of the second support structure shell 312 are evenly arranged at equal angles.

[0038] In addition, considering that the longitudinal telescopic structure 1, the lower drill bit 4, and the upper drill bit 8 themselves have structures that can keep the overall drill bit structure from tilting and drill vertically and steadily, the longitudinal telescopic structure 1, the lower drill bit 4 or the upper drill bit 8 are improved as follows. Specifically, a first drill bit drilling guide mechanism is configured on the main section of the longitudinal telescopic structure 1, a second drill bit drilling guide mechanism is configured on the upper end of the lower drill bit 4, and a second drill bit drilling guide mechanism is configured on the lower end of the upper drill bit 8. A specific structure of the first drill bit drilling guide mechanism, the second drill bit drilling guide mechanism and the third drill bit drilling guide mechanism is expanded as follows. When the longitudinal telescopic structure 1, the lower drill bit 4 or the upper drill bit 8 is improved as follows. A plurality of first drill bit drilling guide mechanisms spaced apart along the length direction are installed on the peripheral side of the main section of the structure 1; the first drill bit drilling guide mechanism comprises a first mounting frame 511 mounted on the longitudinal telescopic structure 1, a rotatable first guide wheel 611 is installed on the first mounting frame 511, and some or all of the first guide wheels 611 are provided with first soil cutting teeth 711 spaced apart along their rotation direction, the rotation tangent direction of the first guide wheel 611 follows the drilling direction, and the first guide wheel 611 does not protrude from the drilling range W1 formed by the lower drilling portion of the lower drill bit 4, thereby avoiding increasing the resistance of the overall drill bit structure when it goes down or up and down. When a plurality of second drill bit drilling guide mechanisms are installed on the circumferential side of the lower drill bit 4 and are spaced apart along the length direction; the second drill bit drilling guide mechanism includes a second mounting frame 512 installed on the lower drill bit 4, and a rotatable second guide wheel 612 is installed on the second mounting frame 512, and some or all of the second guide wheels 612 are provided with spaced apart second soil cutting teeth 712 along their rotation direction, and the rotation tangent direction of the second guide wheel 612 follows the drilling direction, and the second guide wheel 612 does not protrude from the drilling range W1 formed by the lower drilling part of the lower drill bit 4, thereby avoiding increasing the resistance of the overall drill bit structure when moving downward or upward. A plurality of third drill bit drilling guide mechanisms are installed on the peripheral side of the lower end of the upper drill bit 8 and are spaced apart along the length direction; the third drill bit drilling guide mechanism includes a third mounting frame 513 installed on the upper drill bit 8, and a rotatable third guide wheel 613 is installed on the third mounting frame 511, and some or all of the third guide wheels 613 are provided with spaced apart third soil cutting teeth 713 along their rotation direction, and the rotation tangent direction of the third guide wheel 613 follows the drilling direction, and the third guide wheel 613 does not protrude from the drilling range W1 formed by the lower drilling part of the lower drill bit 4, thereby avoiding increasing the resistance of the overall drill bit structure when it moves downward or upward.

[0039] In this embodiment, the power mechanism of the first soil support block 211 and the power mechanism of the second soil support block 311 can be a cylinder, and the power mechanism of the first soil support block 211 and the power mechanism of the second soil support block 311 can also be an oil cylinder. In addition, the power mechanism of the first soil support block 211, the power mechanism of the second soil support block 311 and the longitudinal telescopic structure all work independently.

[0040] Embodiment 2

[0041] Based on the implementation method of the drill bit structure of embodiment 1, see Figure 1-Figure 4 It is during the drilling operation that the first soil support block 211 and the second soil support block 311 complete a complete extension / retraction operation. An upper top frame 9 is installed outside the upper drill bit 8, and a wire rope or a drill rod is hung on the upper top frame 9. After the drill bit structure as a whole enters the soil, and after the longitudinal telescopic structure 1 enters the soil, the first soil support block 211 synchronously extends out of the first support structure 2, and the first support structure 2 supports the longitudinal telescopic structure 1. The extended section of the longitudinal telescopic structure 1 extends to push the lower drill bit 4 downward; then the first soil support block 211 synchronously retracts into the first support structure 2, and then the second soil support block 311 synchronously extends out of the second support structure 3, and the second soil support block 311 supports the lower drill bit 4, and the main section of the longitudinal telescopic structure 1 moves downward and retracts to the extended section, and so on and so forth until the drilling operation is completed. It can be seen from the whole process that when the first soil support block 211 is extended, the second soil support block 311 is in a retracted state, and when the first soil support block 211 is retracted, the second soil support block 311 is in an extended state. It can be understood that the extension / retraction movement of the first soil support block 211 and the extension / retraction movement of the second soil support block 311 are asynchronous reverse movements. After the drilling operation, the upper cutting blade 413 and the upper cutting knife 414 start to rotate in the direction opposite to the rotation direction of the lower cutting blade 411 and the lower cutting knife 412 when drilling downward. During the drilling process, unlike the extruded plate structure of the background technology, it will not always maintain a state. Therefore, while supporting the drill bit structure from tilting, the resistance caused by the first soil support block 211 and the second soil support block 311 is small. In the process of the drill bit withdrawing from the drilling, the upper cutting blade 413 and the upper cutting knife 414 start to rotate in the direction opposite to the rotation direction of the lower cutting blade 411 and the lower cutting knife 412 when drilling downward, providing assistance, and the drill bit withdraws from the drilling process smoothly.

[0042] The above is only an explanation of the best embodiment of the present invention, which should not be construed as a limitation on the claims. The present invention is not limited to the above embodiments, and all changes made within the scope of protection of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A pile foundation drill bit structure, characterized in that: include An upper drill bit (8), the upper end of which is an upper drilling portion for providing an upward assist when the drill bit moves upward; and a lower drill bit (4), the upper end of which is coaxially connected to the lower end of the upper drill bit (8), and the lower end of which is a lower drilling portion for driving the drill bit to drill downward; wherein the drilling range W2 formed by the upper drilling portion is smaller than or equal to the drilling range W1 formed by the lower drilling portion; It also includes a longitudinal telescopic structure (1), a first supporting structure (2) and a second supporting structure (3); The longitudinal telescopic structure (1) comprises an extension section that can be extended downward and a main body section that can be retracted into the extension section; A first supporting structure (2), a longitudinal telescopic structure (1) and a second supporting structure (3) are sequentially distributed between the lower end of the upper drill bit (8) and the upper end of the lower drill bit (4) from top to bottom; The lower end of the upper drill bit (8) is coaxially connected to the upper end of the first support structure (2), the lower end of the first support structure (2) is connected to the main body section of the longitudinal telescopic structure (1), and the first support structure (2) has at least two symmetrically arranged first soil support blocks (211) on the circumference thereof and are extended / retracted under the drive of a power mechanism inside the first support structure (2); The second supporting structure (3) is connected between the extended section of the longitudinal telescopic structure (1) and the upper end of the lower drill bit (4), and the second supporting structure (3) has at least two symmetrically arranged second soil supporting blocks (311) on the circumference thereof and are extended / retracted under the drive of a power mechanism inside the second supporting structure (3); The extension / retraction movement of the first soil support block (211) and the extension / retraction movement of the second soil support block (311) are asynchronous and opposite movements; A plurality of second drill bit drilling guide mechanisms are installed on the circumferential side of the upper end of the lower drill bit (4) and are spaced apart along the length direction; The second drill bit drilling guide mechanism comprises a second mounting frame (512) mounted on the lower drill bit (4), a rotatable second guide wheel (612) being mounted on the second mounting frame (512), a part or all of the second guide wheels (612) being provided with second soil cutting teeth (712) distributed at intervals along the rotation direction thereof, a rotation tangent direction of the second guide wheel (612) following the drilling direction, and the second guide wheel (612) not protruding from a drilling range W1 formed by the lower drilling portion of the lower drill bit (4).

2. A pile foundation drill bit structure according to claim 1, characterized in that: The first support structure (2) comprises a first support structure shell (212) and a power mechanism inside the first support structure shell (212); the first support structure shell (212) is provided with hollow areas which are spaced and have shapes that match those of the first soil support blocks (211) and numbers that match; the first soil support blocks (211) are mounted in the first support structure shell (212), and each first soil support block (211) is synchronously extended / retracted through a corresponding hollow area under the drive of the power mechanism inside the first support structure shell (212).

3. A pile foundation drill bit structure according to claim 2, characterized in that: The first supporting structure shell (212) is a square shell or a cylindrical shell, and its size is smaller than the size of the drilling range W1 formed by the lower drilling portion of the lower drill bit (4); When the first supporting structure shell (212) is a square shell, the number of first soil support blocks (211) extending from opposite sides of the first supporting structure shell (212) is the same, or the number of first soil support blocks (211) extending from each of the four sides of the first supporting structure shell (212) is the same; When the first supporting structure shell (212) is a cylindrical shell, the first soil support blocks (211) extending from the circumference of the first supporting structure shell (212) are evenly arranged at equal angles.

4. A pile foundation drill bit structure according to claim 1, characterized in that: The second support structure (3) comprises a second support structure shell (312) and a power mechanism inside the second support structure shell (312); the second support structure shell (312) is provided with hollow areas which are spaced and have shapes that match those of the second soil support blocks (311) and numbers that match; the second soil support blocks (311) are mounted in the second support structure shell (312), and each of the two second soil support blocks (311) is synchronously extended / retracted through two corresponding hollow areas under the drive of the power mechanism inside the second support structure shell (312).

5. A pile foundation drill bit structure according to claim 4, characterized in that: The second supporting structure shell (312) is a square shell or a cylindrical shell, and its size is smaller than the size of the drilling range W1 formed by the lower drilling portion of the lower drill bit (4); When the second supporting structure shell (312) is a square shell, the number of second soil support blocks (311) extending from opposite sides of the second supporting structure shell (312) is the same, or the number of second soil support blocks (311) extending from each two of the four sides of the second supporting structure shell (312) is the same; When the second supporting structure shell (312) is a cylindrical shell, the second soil supporting blocks (311) extending from the circumference of the second supporting structure shell (312) are evenly arranged at equal angles.

6. A pile foundation drill bit structure according to claim 1, characterized in that: A plurality of first drill bit drilling guide mechanisms are installed on the peripheral side of the main body section of the longitudinal telescopic structure (1) and are spaced apart along the length direction; The first drill bit drilling guide mechanism comprises a first mounting frame (511) mounted on the longitudinal telescopic structure (1); a rotatable first guide wheel (611) is mounted on the first mounting frame (511); part or all of the first guide wheels (611) are provided with first soil cutting teeth (711) distributed at intervals along their rotation direction; the rotation tangent direction of the first guide wheel (611) follows the drilling direction, and the first guide wheel (611) does not protrude from a drilling range W1 formed by a lower drilling portion of the lower drill bit (4).

7. A pile foundation drill bit structure according to claim 1, characterized in that: A plurality of third drill bit drilling guide mechanisms are installed on the circumferential side of the lower end of the upper drill bit (8) and are spaced apart along the length direction; The third drill bit drilling guide mechanism comprises a third mounting frame (513) mounted on the upper drill bit (8), a rotatable third guide wheel (613) being mounted on the third mounting frame (513), a part or all of the third guide wheels (613) being provided with third soil cutting teeth (713) distributed at intervals along the rotation direction thereof, a rotation tangent direction of the third guide wheel (613) following the drilling direction, and the third guide wheel (613) not protruding from a drilling range W1 formed by a lower drilling portion of the lower drill bit (4); The head of the lower drilling portion of the lower drill bit (4) has a spiral lower cutting blade (411) located at the upper end of the lower cutting blade (411) to form multiple layers of circumferentially distributed lower cutting knives (412); the head of the upper drilling portion has a spiral upper cutting blade (413) located at the lower end of the upper cutting blade (413) to form multiple layers of circumferentially distributed upper cutting knives (414); and the upper cutting blade (413) and the upper cutting knives (414) are started when the drill bit is about to exit drilling, and their rotation direction is opposite to the rotation direction of the lower cutting blade (411) and the lower cutting knives (412) when drilling downwards; The upper cutting blade (414) of the upper drilling part forms the drilling range W2, and the lower cutting blade (412) of the lower drilling part forms the drilling range W1.

8. A drilling method, based on the pile foundation drill bit structure according to any one of claims 1 to 7, characterized in that: After the longitudinal telescopic structure (1) enters the soil, the first soil support block (211) is synchronously extended out of the first support structure (2), the first support structure (2) supports the longitudinal telescopic structure (1), and the extended section of the longitudinal telescopic structure (1) extends to push the lower drill bit (4) downward to drill a hole; then the first soil support block (211) is synchronously retracted into the first support structure (2), and then the second soil support block (311) is synchronously extended out of the second support structure (3), the second soil support block (311) supports the lower drill bit (4), and the main section of the longitudinal telescopic structure (1) moves downward and retracts to its extended section, and this process is repeated until the drilling operation is completed. After the drilling operation, the upper cutting blade (413) and the upper cutting knife (414) start to rotate in a direction opposite to the rotation direction of the lower cutting blade (411) and the lower cutting knife (412) when drilling downward.

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