Multi-channel telescopic drill rod and multifunctional telescopic drilling tool

Abstract

The invention discloses a multi-channel telescopic drill rod and a multifunctional telescopic drilling tool, and belongs to the field of pile foundation engineering drilling tools. According to the multi-channel telescopic drill rod and the multifunctional telescopic drilling tool, synchronous stretching and retracting of the telescopic drill rod are achieved through ingenious structural design, the accuracy and stability of telescopic motion control of the telescopic drill rod are guaranteed, meanwhile, a plurality of fluid channels are constructed in the telescopic drill rod through the corrugated telescopic pipes which are annularly sleeved together, the structure is simple and compact, and operation is convenient. The telescopic drill rod is simple in structure, convenient to manufacture and implement and capable of being matched with drill bits of various technologies due to the fact that the multiple fluid channels are built in the telescopic drill rod, and applicability of the telescopic drill rod is greatly improved. In addition, according to the multifunctional telescopic drilling tool formed by matching the telescopic drill rod with drill bits of various technologies, frequent rod connecting operation can be reduced through multi-stage stretching of the telescopic drill rod, the construction automation degree can be improved, the construction operation complexity can be reduced, and the construction efficiency can be improved; and the method can be used for cast-in-situ bored pile construction, stirring pile construction, high-pressure jet grouting pile construction, threaded expansion body steel pile construction and the like.

Description

Technical Field

[0001] The invention relates to a construction engineering drilling tool, and more particularly to a multi-channel telescopic drilling rod and a multifunctional telescopic drilling tool. Background Art

[0002] Pile foundation engineering is a key part of construction engineering, and its construction quality is directly related to the stability and safety of the entire structure. In pile foundation construction, drilling tools are the main construction tools, and their performance and efficiency directly affect the progress and quality of construction. With the development of the construction industry, the demand for pile foundation construction under complex geological conditions is increasing, which puts higher requirements on the performance of drilling tools.

[0003] Conventional construction drilling tools have the following main problems and shortcomings in practical applications:

[0004] (1) Adaptability issues: Traditional drilling tools are often only suitable for specific types of geological conditions. For variable underground environments, such as alternating soft and hard strata, traditional drilling tools may not be able to drill effectively or may have low drilling efficiency.

[0005] (2) Construction efficiency issues: In some projects, due to the design limitations of drilling tools, they need to be frequently replaced or adjusted, which not only increases the complexity of construction but also reduces construction efficiency.

[0006] (3) Low degree of automation: Many traditional drilling tools rely on manual control in operation and lack automation functions, which to a certain extent limits the accuracy and efficiency of construction.

[0007] (4) Lack of versatility: With the diversification of engineering requirements, single-function drilling tools can no longer meet the needs of modern pile foundation projects, and multifunctional drilling tools that can adapt to different construction processes are needed.

[0008] (5) Structural complexity: Some drilling tools have complex structures, which makes maintenance difficult and prone to failure under complex geological conditions, affecting the construction progress.

[0009] The reasons for these problems and shortcomings may include limitations in design concepts, limitations in material properties, deficiencies in manufacturing processes, and insufficient understanding of complex geological conditions. When solving these problems, difficulties may include the difficulty of technological innovation, pressure on cost control, limitations of existing manufacturing processes, and the complexity of the on-site construction environment.

[0010] In order to overcome these problems, some telescopic drilling tools have also appeared in the prior art. Telescopic drill rods can be used to connect different drill bits to solve the adaptability and construction efficiency problems of traditional drilling tools. For example, Chinese patent No. ZL201511021903.9 discloses "a telescopic drill rod and a mixing pile machine with a telescopic drill rod" (the patent authorization announcement date is June 29, 2018). The telescopic drill rod consists of an outer drill rod and an inner drill rod. The outer drill rod is a multi-stage slot-type telescopic outer drill rod. The inner drill rod is a telescopic inner drill rod of a multi-stage screw nut or a multi-stage hydraulic telescopic cylinder, and the telescopic outer drill rod and the telescopic inner drill rod are sleeved together layer by layer; the top of the outermost outer drill rod of the telescopic outer drill rod is connected to the external power, the top of the innermost inner drill rod of the telescopic inner drill rod is fixed to the transmission shaft used for conveying slurry and clutch feeding, and the bottom of the innermost outer drill rod of the telescopic outer drill rod and the bottom of the outermost inner drill rod of the telescopic inner drill rod are fixed on the same bottom connection plate, so that the telescopic outer drill rod and the telescopic inner drill rod are linked. Although the telescopic drill rod in this patent application can be used for mixing pile construction under space-constrained working conditions, the structural design and transmission principle of the telescopic drill rod are relatively complex, and the mutual transmission of the friction side effect force of the inner and outer threads is required to realize the step-by-step extension and contraction of the inner and outer drill rods. This can be achieved in theory, but in reality, due to the matching error relationship between the inner and outer drill rods, the obstruction of pollutants between the inner and outer threads, and other uncertain factors, there is a certain uncertainty in the actual extension and contraction state of the drill rod, and it is difficult to implement and apply it in practice. Furthermore, the telescopic drill rod utilizes the innermost inner drill rod and the transmission shaft at its top to realize slurry transportation, and cannot realize multi-channel transportation design, and thus has great limitations in application scenarios, and can only be used for mixing pile construction. Summary of the invention

[0011] 1. Technical problem to be solved by the invention

[0012] The purpose of the present invention is to overcome the above-mentioned shortcomings of the existing telescopic drill rod and telescopic drilling tool, and provide a multi-channel telescopic drill rod and a multi-functional telescopic drilling tool. The technical solution of the present invention is adopted, and the synchronous telescopic of the telescopic drill rod is realized through ingenious structural design, so as to ensure the accuracy and stability of the telescopic motion control of the telescopic drill rod, and improve the verticality and precision of the construction drill rod. At the same time, a multi-fluid channel is constructed in the telescopic drill rod by using a corrugated telescopic tube that is sleeved together. Not only is the structure simple and compact, but also the manufacture and implementation are convenient. Moreover, the establishment of the multi-fluid channel in the telescopic drill rod makes it possible to cooperate with a variety of process drill bits, which greatly improves the applicability of the telescopic drill rod. In addition, the multi-functional telescopic drilling tool formed by the telescopic drill rod in combination with a variety of process drill bits can reduce the frequent rod connection operation by using the multi-stage telescopic telescopic of the telescopic drill rod, can improve the degree of construction automation, reduce the complexity of construction operation, and improve construction efficiency; the multi-channel design of the telescopic drill rod can enable the drilling tool to establish different fluid channels, which can be used for bored pile construction, mixing pile construction, high-pressure rotary jet pile construction and threaded expanded steel pile construction, etc.

[0013] 2. Technical solution

[0014] In order to achieve the above object, the technical solution provided by the present invention is:

[0015] A multi-channel telescopic drill rod of the present invention comprises a synchronous telescopic rod body part and a fluid channel part, wherein:

[0016] The synchronous telescopic rod body part includes a primary fixed rod body, an intermediate telescopic rod body, a final telescopic rod body, a primary screw and an intermediate transmission screw. The primary fixed rod body, the intermediate telescopic rod body and the final telescopic rod body are sleeved together step by step from the outside to the inside, and the telescopic rod bodies of each level are axially locked relative to the primary fixed rod body; the primary screw and the intermediate transmission screw are arranged on the inner side of the primary fixed rod body, the intermediate telescopic rod body and the final telescopic rod body, and the primary screw and the intermediate transmission screws of each level are threadedly sleeved together step by step from the inside to the outside; the intermediate transmission screws of each level are relatively rotatably connected with the intermediate telescopic rod body of the corresponding level through an annular relay, and the primary screw and the intermediate transmission screws of each level are threadedly matched with the corresponding intermediate telescopic rod body of the next level and the final telescopic rod body; the telescopic rod bodies of each level are driven to rotate to drive the synchronous axial telescopic movement of the telescopic rod bodies relative to the primary fixed rod body;

[0017] The fluid channel part includes a fluid channel arranged on the primary screw and a bellows expansion tube arranged between the lower end of the primary screw and the lower end of the final expansion rod body. The fluid channel is provided with at least two channels from the inside to the outside on the primary screw. The upper end of the bellows expansion tube is connected to the lower end of the primary screw through a multi-channel rotary joint, and the bellows expansion tube is formed from the inside to the outside of the ring to form a tube channel corresponding to the above-mentioned fluid channel, and each tube channel is connected to the corresponding channel opening at the lower end of the final expansion rod body.

[0018] Furthermore, the first-stage fixed rod body, the intermediate telescopic rod body and the final telescopic rod body are all cylindrical structures, and anti-rotation guide ribs are provided between the first-stage fixed rod body and the adjacent intermediate telescopic rod body, between the intermediate telescopic rod bodies of each stage, and between the final telescopic rod body and the adjacent intermediate telescopic rod body.

[0019] Furthermore, the upper end of each level of the intermediate transmission screw is provided with a screw connecting part, and the upper end of each level of the intermediate telescopic rod body is provided with an intermediate rod body connecting part, the screw connecting part is sleeved on the outside of the corresponding intermediate rod body connecting part, and the annular relay is arranged between the corresponding screw connecting part and the intermediate rod body connecting part to realize axial connection and relative rotation between the screw connecting part and the intermediate rod body connecting part.

[0020] Furthermore, the annular servomotor is a circular ring structure.

[0021] Furthermore, the primary screw is a hollow screw, and the fluid channel is composed of concentric tubes which are sleeved layer by layer on the inner side of the primary screw.

[0022] A multifunctional telescopic drilling tool of the present invention comprises a power head assembly and a process drill bit, and also comprises the above-mentioned multi-channel telescopic drill rod, wherein the power head assembly is connected to the process drill bit through the multi-channel telescopic drill rod, wherein:

[0023] The power head assembly has a multi-channel flow divider, and independently driven drill pipe rotating joints and screw driving joints, the multi-channel flow divider is arranged at the upper end of the screw driving joint, the drill pipe rotating joint is located outside the screw driving joint, the upper end of the primary fixed rod body of the multi-channel telescopic drill pipe is fixedly installed on the drill pipe rotating joint, the upper end of the primary screw of the multi-channel telescopic drill pipe is fixedly installed on the screw driving joint, and each fluid channel on the primary screw is respectively connected to the corresponding flow diversion channel in the multi-channel flow divider;

[0024] The process drill bit is installed at the lower end of the final telescopic rod body of the multi-channel telescopic drill rod, and the corresponding tube cavity in the process drill bit is communicated with the corresponding channel opening on the final telescopic rod body.

[0025] Furthermore, the power head assembly also includes a box body, and a telescopic drive hydraulic motor and a drill rod drive hydraulic motor are respectively placed flat on the side walls of the box body. The telescopic drive hydraulic motor is connected to the screw drive joint through a screw drive transmission mechanism, and the drill rod drive hydraulic motor is connected to the drill rod rotary joint through a drill rod drive transmission mechanism.

[0026] Furthermore, the drill rod drive transmission mechanism and the screw drive transmission mechanism both adopt planetary gear reduction mechanisms.

[0027] Furthermore, the screw drive joint is a hollow rotating shaft, the upper end of which extends out of the box body, and the multi-channel diverter includes a rotary diverter seat and a channel tube, the channel tube is sleeved on the inner side of the screw drive joint to form a concentric annularly distributed diverter channel, the rotary diverter seat is rotatably installed on the upper end of the screw drive joint, and the rotary diverter seat is provided with a pipe joint connected to the corresponding diverter channel.

[0028] Furthermore, the process drill bit includes one of a drilling drill bit, a mixing pile drill bit, a high-pressure jetting drill bit and a thread enlarged steel pile drill bit, wherein:

[0029] The drilling drill bit has a drilling drill tip and a plurality of spiral wing plates located on the upper portion of the drilling drill tip. The drilling drill bit is also provided with at least two fluid inlets and outlets axially spaced and connected to corresponding lumens. The fluid inlets and outlets are matched with plugs, and different drilling circulation processes are formed by plugging different fluid inlets and outlets.

[0030] The mixing pile drill bit has a mixing drill tip and a plurality of mixing blades distributed on the side of the mixing pile drill bit, and the mixing pile drill bit is also provided with at least two fluid nozzles arranged axially at intervals and connected to corresponding lumens;

[0031] The high-pressure jet grouting drill bit comprises a jet grouting drill tip and at least one high-pressure nozzle connected to a corresponding lumen;

[0032] The upper end of the threaded enlarged steel pile drill bit is provided with a steel pile joint, which is fixed to the lower end of the final telescopic rod body. The steel pile joint and the threaded enlarged steel pile drill bit are plug-fitted with a non-circular cross-section axial hole.

[0033] 3. Beneficial effects

[0034] Compared with the existing known technologies, the technical solution provided by the present invention has the following significant effects:

[0035] (1) A multi-channel telescopic drill rod of the present invention comprises a synchronous telescopic rod body part and a fluid channel part. The synchronous telescopic rod body part comprises a primary fixed rod body, an intermediate telescopic rod body, a final telescopic rod body, a primary screw and an intermediate transmission screw. The synchronous telescopic drill rod is telescoped by the screw and the threaded transmission of the primary screw and the primary rod bodies, thereby ensuring the accuracy and stability of the telescopic motion control of the telescopic drill rod and improving the verticality and precision of the construction drill rod. The fluid channel part comprises a fluid channel arranged on the primary screw and a corrugated telescopic tube arranged between the lower end of the primary screw and the lower end of the final telescopic rod body. Multiple fluid channels are constructed in the telescopic drill rod by using the corrugated telescopic tubes sleeved together. Not only is the structure simple and compact, and the manufacture and implementation are convenient, but also the establishment of multiple fluid channels in the telescopic drill rod makes it possible to cooperate with a variety of process drill bits, thereby greatly improving the applicability of the telescopic drill rod.

[0036] (2) A multi-channel telescopic drill rod of the present invention has a screw connection portion at the upper end of each intermediate transmission screw rod, and an intermediate rod body connection portion at the upper end of each intermediate telescopic rod body. The screw connection portion is sleeved on the outer side of the corresponding intermediate rod body connection portion, and an annular relay is arranged between the corresponding screw connection portion and the intermediate rod body connection portion to realize axial connection and relative rotation of the screw connection portion and the intermediate rod body connection portion. The adoption of this structure not only facilitates the connection between the intermediate transmission screw rod and the corresponding intermediate rod body, but also facilitates the threaded connection between the intermediate telescopic rod body and the final telescopic rod body and the upper screw rod, thereby cleverly realizing the synchronous telescopic movement of the telescopic rod body.

[0037] (3) A multifunctional telescopic drilling tool of the present invention comprises a power head assembly, a process drill bit and the above-mentioned multi-channel telescopic drill rod, wherein the power head assembly is connected to the process drill bit through the multi-channel telescopic drill rod, the power head assembly has a multi-channel flow divider, and an independently driven drill rod rotary joint and a screw drive joint, the process drill bit is installed at the lower end of the final telescopic rod body of the multi-channel telescopic drill rod, and the corresponding tube cavity in the process drill bit is connected to the corresponding channel opening on the final telescopic rod body; the multifunctional telescopic drilling tool formed by the telescopic drill rod and a plurality of process drill bits can reduce the frequent rod connection operation by utilizing the multi-stage telescopic extension of the telescopic drill rod, can improve the degree of construction automation, reduce the complexity of construction operation, and improve construction efficiency; the multi-channel design of the telescopic drill rod can enable the drilling tool to establish different fluid channels, which can be used for bored pile construction, mixing pile construction, high-pressure rotary jet pile construction and threaded enlarged steel pile construction, etc.

[0038] (4) A multifunctional telescopic drilling tool of the present invention, wherein the power head assembly also includes a box body, on the side walls of which are respectively flatly provided a telescopic driving hydraulic motor and a drill rod driving hydraulic motor, the telescopic driving hydraulic motor is connected to the screw driving joint through a screw driving transmission mechanism, and the drill rod driving hydraulic motor is connected to the drill rod rotary joint through a drill rod driving transmission mechanism; the hydraulic motor adopts a flat installation structure, which reduces the height dimension of the power head, and can realize efficient and accurate construction work in a limited space in conjunction with a multi-channel telescopic drill rod; dual hydraulic motors are used for propulsion, the mechanical structure is simple, and maintenance is convenient;

[0039] (5) A multifunctional telescopic drilling tool of the present invention, wherein both the drill rod driving transmission mechanism and the screw driving transmission mechanism adopt a planetary gear reduction mechanism, has a compact structure, high transmission efficiency, and can withstand large loads;

[0040] (6) The multifunctional telescopic drill bit of the present invention can adapt to various geological conditions, improve construction efficiency, have an automated operation function, and has a simple and reliable structure. The multifunctional telescopic drill bit realizes efficient and precise construction operations in a limited space through integrated innovative design, while reducing the follow-up work during construction and improving the flexibility and adaptability of construction. Through the application of the multifunctional telescopic drill bit, the construction quality of pile foundation projects can be effectively improved, the construction period can be shortened, and the project cost can be reduced, thereby meeting the high standards of pile foundation construction in modern construction projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the three-dimensional structure of a multi-channel telescopic drill rod in an extended state according to the present invention;

[0042] Figure 2 It is a schematic cross-sectional structure diagram of a multi-channel telescopic drill rod in an extended state of the present invention;

[0043] Figure 3 It is a schematic diagram of the three-dimensional structure of a multi-channel telescopic drill rod in a contracted state according to the present invention;

[0044] Figure 4 It is a schematic cross-sectional structure diagram of a multi-channel telescopic drill rod of the present invention in a contracted state;

[0045] Figure 5 It is a schematic diagram of different combination states of a multifunctional telescopic drilling tool of the present invention;

[0046] Figure 6 It is a three-dimensional structural schematic diagram of a power head assembly in a multifunctional telescopic drilling tool of the present invention at an angle;

[0047] Figure 7 It is a three-dimensional structural schematic diagram of a power head assembly in a multifunctional telescopic drilling tool of the present invention from another angle;

[0048] Figure 8 It is a schematic planar cross-sectional structure diagram of a power head assembly in a multifunctional telescopic drilling tool of the present invention;

[0049] Fig. 9 It is a three-dimensional cross-sectional structural schematic diagram of a power head assembly in a multifunctional telescopic drilling tool of the present invention;

[0050] Fig.10 It is a three-dimensional structural schematic diagram of a telescopic drilling tool used in conjunction with a drilling drill bit of the present invention;

[0051] Fig.11 It is a schematic cross-sectional structure diagram of a telescopic drilling tool used in conjunction with a drilling drill bit of the present invention;

[0052] Fig.12 It is a three-dimensional structural schematic diagram of a telescopic drilling tool used in conjunction with a mixing pile drill bit of the present invention;

[0053] Fig.13 It is a schematic cross-sectional view of a telescopic drilling tool used in conjunction with a mixing pile drill bit of the present invention;

[0054] Fig.14 It is a three-dimensional structural schematic diagram of a telescopic drilling tool used in conjunction with a high-pressure jet-jet drill bit of the present invention;

[0055] Fig.15 It is a cross-sectional structural schematic diagram of a telescopic drilling tool used in conjunction with a high-pressure jet-jet drill bit of the present invention;

[0056] Fig.16 It is a schematic diagram of the combined state of a telescopic drilling tool used in conjunction with a thread enlarged steel pile drill bit of the present invention;

[0057] Fig.17The present invention is a schematic diagram of a telescopic drilling tool used in conjunction with a thread enlarged body steel pile drill bit in a disassembled state.

[0058] Explanation of the symbols in the schematic diagram:

[0059] 10. Multi-channel telescopic drill rod; 11. First-stage fixed rod body; 12. Intermediate telescopic rod body; 12-1. Intermediate rod body connection part; 13. Final telescopic rod body; 13-1. Channel opening; 14. Anti-rotation guide rib; 15. First-stage screw rod; 15-1. Fluid channel; 16. Intermediate transmission screw rod; 16-1. Screw rod connection part; 17. Ring relay; 18. Corrugated telescopic tube; 18-1. Multi-channel rotary joint;

[0060] 20. Power head assembly; 21. Box; 22. Telescopic drive hydraulic motor; 23. Drill rod drive hydraulic motor; 24. Multi-channel diverter; 24-1. Rotary diverter seat; 24-2. Channel pipe; 24-3. Diverter channel; 25. Drill rod rotary joint; 26. Screw drive joint; 27. Drill rod drive transmission mechanism; 28. Screw drive transmission mechanism;

[0061] 30. Process drill bit; 30A. Drilling drill bit; 30A-1. Drilling drill tip; 30A-2. Spiral wing plate; 30A-3. Fluid inlet and outlet; 30A-4. Plug; 30B. Mixing pile drill bit; 30B-1. Mixing drill tip; 30B-2. Mixing blade; 30B-3. Fluid nozzle; 30C. High-pressure jet drill bit; 30C-1. Jet-jet drill tip; 30C-2. High-pressure nozzle; 30D. Threaded enlarged steel pile drill bit; 30D-1. Steel pile joint. DETAILED DESCRIPTION

[0062] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments.

[0063] [Example 1]

[0064] like Figures 1 to 4 As shown, this embodiment relates to a multi-channel telescopic drill rod, which has the functions of telescopic adjustment of the drill rod length and multiple fluid channels. The multi-channel telescopic drill rod includes a synchronous telescopic rod body part and a fluid channel part, wherein:

[0065] The synchronous telescopic rod body part includes a primary fixed rod body 11, an intermediate telescopic rod body 12, a final telescopic rod body 13, a primary screw 15 and an intermediate transmission screw 16. The primary fixed rod body 11, the intermediate telescopic rod body 12 and the final telescopic rod body 13 are sleeved together step by step from the outside to the inside, and the telescopic rod bodies at each level are axially fixed relative to the primary fixed rod body 11, that is, the intermediate telescopic rod bodies 12 and the final telescopic rod body 13 at each level can only move relatively telescopically but cannot rotate relatively, and the diameter of each rod body gradually decreases from the primary fixed rod body 11 to the final telescopic rod body 13. The primary screw 15 and the intermediate transmission screw 16 are arranged on the inner side of the primary fixed rod body 11, the intermediate telescopic rod body 12 and the final telescopic rod body 13, and the primary screw 15 and the intermediate transmission screws 16 at each level are sleeved together step by step from the inside to the outside, that is, the diameters of the primary screw 15 and the intermediate transmission screws 16 at each level increase step by step. The intermediate transmission screws 16 of each level are connected to the intermediate telescopic rod body 12 of the corresponding level through the annular relay 17 for relative rotation, so that the intermediate transmission screws 16 and the intermediate telescopic rod body 12 of the corresponding level can rotate relative to each other but cannot move axially; the primary screw 15 and the intermediate transmission screws 16 of each level are threadedly matched with the corresponding intermediate telescopic rod body 12 of the next level and the final telescopic rod body 13, and the primary screw 15 is driven to rotate to drive the telescopic rod bodies of each level to synchronously axially telescopically move relative to the primary fixed rod body 11. The primary screw 15 and the primary fixed rod body 11 can rotate relative to each other and the axial movement is also restricted. When the primary screw 15 rotates, the secondary intermediate telescopic rod body 12 moves axially on the primary screw 15, driving the intermediate transmission screw 16 of the same level to move axially together. Since the secondary intermediate transmission screw 16 is threadedly matched with the primary screw 15, the secondary intermediate transmission screw 16 also rotates together at this time; the rotation of the secondary intermediate transmission screw 16 drives the intermediate telescopic rod body 12 of the next level to move axially, and at the same time drives the intermediate transmission screw 16 of the next level to move axially and rotate at the same time, and transmits the power step by step until the final telescopic rod body 13 is driven to move axially. In this way, the intermediate telescopic rod bodies 12 of each level and the final telescopic rod body 13 can synchronously telescope axially relative to the primary fixed rod body 11, ensuring the accuracy and stability of the telescopic motion control of the telescopic drill rod, and improving the verticality and precision of the construction drill rod. The number of intermediate telescopic rod bodies 12 and intermediate transmission screws 16 is equal, and the specific number can be determined according to the needs of the telescopic stroke. Figure 3 and Figure 4 As shown, the length of the multi-channel telescopic drill rod after contraction is equivalent to the length of the primary fixed rod body 11, as shown in FIG. Figure 1 and Figure 2 As shown, the maximum extension length can reach several times the length of the primary fixed rod 11. For the sake of illustration, Figures 1 to 4The specific implementation scheme of setting two intermediate telescopic rod bodies 12 is provided, and the two intermediate telescopic rod bodies 12 are respectively a secondary intermediate telescopic rod body and a tertiary intermediate telescopic rod body, and correspondingly, the two intermediate transmission screws 16 are respectively a secondary transmission screw and a tertiary transmission screw. When the telescopic length of the telescopic drill rod needs to be increased, it can be achieved by increasing the number of sections of the intermediate telescopic rod body 12 and the intermediate transmission screw 16.

[0066] The fluid channel part includes a fluid channel 15-1 provided on the primary screw 15, and a bellows expansion joint 18 provided between the lower end of the primary screw 15 and the lower end of the final expansion rod 13. There are at least two fluid channels 15-1 on the primary screw 15 from the inside to the outside, and each fluid channel 15-1 is distributed in an annular manner from the center to the outside. The upper end of the bellows expansion joint 18 is connected to the lower end of the primary screw 15 through a multi-channel rotary joint 18-1, so that the primary screw 15 can rotate freely relative to the bellows expansion joint 18 and maintain the connection and sealing of each channel. The bellows expansion joint 18 is formed from the inside to the outside of the ring sleeve to form a tube channel corresponding to the above-mentioned fluid channel 15-1, and each tube channel is connected to the corresponding channel opening 13-1 at the lower end of the final expansion rod 13. In other words, the central tube cavity of the innermost bellows expansion joint 18 is a fluid channel, and the annular interlayer between adjacent bellows expansion joints 18 is a fluid channel. The number of fluid channels can be determined according to the number of ring sleeves of the bellows expansion joint 18. The bellows expansion tube 18 can be made of high-strength material to withstand the pressure of high-pressure fluid. The multi-channel rotary joint 18-1 is similar to the existing rotary joint, which realizes the relative rotation of the connected pipelines and can be used for the transportation of fluids such as gas and liquid. The bellows expansion tube 18 is used to construct multiple fluid channels in the telescopic drill rod, which is not only simple and compact in structure, easy to manufacture and implement, but also the establishment of multiple fluid channels in the telescopic drill rod makes it possible to cooperate with a variety of process drill bits, greatly improving the applicability of the telescopic drill rod.

[0067] catch Figure 1 and Figure 3 As shown, in this embodiment, the above-mentioned first-stage fixed rod body 11, the intermediate telescopic rod body 12 and the final telescopic rod body 13 are all cylindrical structures, and anti-rotation guide ribs 14 are provided between the first-stage fixed rod body 11 and the adjacent intermediate telescopic rod body 12, between the intermediate telescopic rod bodies 12 at each level, and between the final telescopic rod body 13 and the adjacent intermediate telescopic rod body 12. The cylindrical rod body is easy to make, and after the steel cage is lowered, a multi-channel telescopic drill rod can be inserted into the inner side of the steel cage for use as a grouting conduit. The anti-rotation guide ribs 14 are slidably matched with the corresponding guide grooves, so that the rod bodies at each level can move smoothly and prevent relative rotation.

[0068] Reference Figure 2As shown, in this embodiment, the upper ends of the intermediate transmission screws 16 of each level are provided with screw connecting parts 16-1, and the upper ends of the intermediate telescopic rod bodies 12 of each level are provided with intermediate rod body connecting parts 12-1. The screw connecting parts 16-1 are sleeved on the outer sides of the corresponding intermediate rod body connecting parts 12-1, and the annular relay 17 is provided between the corresponding screw connecting parts 16-1 and the intermediate rod body connecting parts 12-1 to realize the axial connection and relative rotation of the screw connecting parts 16-1 and the intermediate rod body connecting parts 12-1. The diameter of the screw connecting part 16-1 is slightly larger than the diameter of the intermediate transmission screw 16, the cross section of the intermediate rod body connecting part 12-1 is inverted "U" shape, and the inner free end of the intermediate rod body connecting part 12-1 is sleeved on the inner side of the screw connecting part 16-1, so that the screw connecting part 16-1 and the intermediate rod body connecting part 12-1 are connected, and the inner free end of the intermediate rod body connecting part 12-1 can also be used to realize the threaded connection with the corresponding screw, so as to cleverly realize the synchronous telescopic movement of the telescopic rod body. The above-mentioned annular relay 17 is an annular structural part, such as a steel ring, etc., and corresponding annular grooves are respectively provided between the screw connecting part 16-1 and the intermediate rod body connecting part 12-1. The annular relay 17 is located in the annular groove, so that the corresponding level of the intermediate telescopic rod body 12 and the intermediate transmission screw 16 can be axially connected together to transmit the axial force, and at the same time, the free rotation of the two can be guaranteed. Of course, the annular relay 17 can also be a plurality of annularly distributed steel balls, etc.

[0069] like Figure 2 and Figure 4 As shown, in this embodiment, the primary screw 15 is a hollow screw, and the fluid channel 15-1 is composed of concentric tubes that are sleeved layer by layer on the inner side of the primary screw 15. The concentric tubes are separated from the inner wall of the primary screw 15 and the adjacent concentric tubes are connected together by spacers to ensure the smooth flow of the annular fluid channel 15-1, and the formed fluid channel 15-1 is conveniently corresponding to the tube channel formed by the corrugated telescopic tube 18 through the multi-channel rotary joint 18-1.

[0070] The multi-channel telescopic drill rod of this embodiment realizes the synchronous extension and retraction of the telescopic drill rod through ingenious structural design, ensures the accuracy and stability of the telescopic motion control of the telescopic drill rod, improves the verticality and precision of the construction drill rod, and simultaneously constructs multiple fluid channels in the telescopic drill rod by using the corrugated telescopic tubes sleeved together. Not only is the structure simple and compact, and easy to manufacture and implement, but the establishment of multiple fluid channels in the telescopic drill rod makes it possible to cooperate with a variety of process drill bits, thereby greatly improving the applicability of the telescopic drill rod.

[0071] [Example 2]

[0072] like Figure 5As shown, this embodiment relates to a multifunctional telescopic drilling tool. The multifunctional telescopic drilling tool comprises a power head assembly 20, a process drill bit 30 and the above-mentioned multi-channel telescopic drill rod 10. The power head assembly 20 is connected to the process drill bit 30 through the multi-channel telescopic drill rod 10. The power head assembly 20 is used to drive the telescopic movement of the multi-channel telescopic drill rod 10 and the overall rotation of the drilling tool. The multi-channel telescopic drill rod 10 is used to lengthen and advance the drilling tool, and establish a fluid channel with the process drill bit 30 to meet the needs of different construction processes. Among them,

[0073] like Figure 6 and Figure 7 As shown, the power head assembly 20 has a multi-channel diverter 24, and independently driven drill pipe rotary joints 25 and screw drive joints 26. The multi-channel diverter 24 is arranged at the upper end of the screw drive joint 26 for connecting to the ground fluid pipeline. The drill pipe rotary joint 25 is located on the outside of the screw drive joint 26. The upper end of the primary fixed rod body 11 of the multi-channel telescopic drill pipe 10 is fixedly mounted on the drill pipe rotary joint 25, which can drive the entire multi-channel telescopic drill pipe 10 to rotate. The upper end of the primary screw 15 of the multi-channel telescopic drill pipe 10 is fixedly mounted on the screw drive joint 26, and each fluid channel 15-1 on the primary screw 15 is respectively connected to the corresponding diverter channel 24-3 in the multi-channel diverter 24; the screw drive joint 26 can drive the multi-channel telescopic drill pipe 10 to perform telescopic movement. For further reference Figure 8 and Fig. 9 As shown, the power head assembly 20 also includes a box body 21, and a telescopic driving hydraulic motor 22 and a drill rod driving hydraulic motor 23 are placed flat on the side walls of the box body 21, respectively. The telescopic driving hydraulic motor 22 is connected to the screw driving joint 26 through a screw driving transmission mechanism 28, and the drill rod driving hydraulic motor 23 is connected to the drill rod rotating joint 25 through a drill rod driving transmission mechanism 27. The hydraulic motor adopts a flat installation structure, which reduces the size of the power head in the height direction. With the multi-channel telescopic drill rod 10, efficient and accurate construction operations can be achieved in a limited space; dual hydraulic motors are used for propulsion, and the mechanical structure is simple and maintenance is convenient. In this embodiment, the telescopic driving hydraulic motor 22 and the drill rod driving hydraulic motor 23 are placed on both sides of the box body 21, which is convenient for space arrangement. The above-mentioned drill rod driving transmission mechanism 27 and the screw driving transmission mechanism 28 both adopt planetary gear reduction mechanisms, which are compact in structure, high in transmission efficiency, and can withstand large loads. The planetary gear reduction mechanism is an existing reduction mechanism, so its specific structural principle will not be described again.

[0074] Furthermore, if Figure 8 and Fig. 9As shown, the screw drive joint 26 is a hollow shaft, the upper end of which extends out of the housing 21, and the multi-channel diverter 24 includes a rotary diverter seat 24-1 and a channel tube 24-2, the channel tube 24-2 is sleeved on the inner side of the screw drive joint 26 to form a concentric annular distribution of diverter channels 24-3, the rotary diverter seat 24-1 is rotatably mounted on the upper end of the screw drive joint 26, and the rotary diverter seat 24-1 is provided with a pipe joint connected to the corresponding diverter channel 24-3. A rotary sealed annular distribution cavity is also provided at the corresponding pipe joint, and each pipe joint can be connected to the corresponding diverter channel 24-3 through the corresponding annular distribution cavity, so that during the rotation of the screw drive joint 26, the rotary diverter seat 24-1 and the pipe joint thereon can be relatively fixed, so as to realize fluid diversion and prevent the fluid pipeline from being entangled.

[0075] The process drill bit 30 is installed at the lower end of the final telescopic rod body 13 of the multi-channel telescopic drill rod 10, and the corresponding tube cavity in the process drill bit 30 is connected to the corresponding channel opening 13-1 on the final telescopic rod body 13. The multifunctional telescopic drilling tool formed by the telescopic drill rod and a variety of process drill bits 30 can reduce the frequent rod connection operation by utilizing the multi-stage telescopic telescopic drill rod, improve the degree of construction automation, reduce the complexity of construction operations, and improve construction efficiency. The multi-channel design of the telescopic drill rod can enable the drilling tool to establish different fluid channels, which can be used for bored pile construction, mixing pile construction, high-pressure rotary jet pile construction, and threaded expanded steel pile construction, etc., solving the adaptability problem of traditional drilling tools.

[0076] In this embodiment, the process drill bit 30 includes one of a drilling drill bit 30A, a mixing pile drill bit 30B, a high-pressure jetting drill bit 30C and a threaded enlarged steel pile drill bit 30D, wherein:

[0077] like Fig.10 and Fig.11As shown, the drilling drill bit 30A has a drilling drill tip 30A-1 and a plurality of spiral wing plates 30A-2 located on the upper part of the drilling drill tip 30A-1, and the spiral wing plates 30A-2 are provided with a plurality of alloy cutters. The drilling drill bit 30A is also provided with at least two fluid inlets and outlets 30A-3 arranged axially at intervals and connected to the corresponding lumens, and the fluid inlets and outlets 30A-3 are equipped with plugs 30A-4, and different drilling circulation processes are formed by plugging different fluid inlets and outlets 30A-3. During the drilling construction, the drilling drill bit 30A is mainly driven by the power head assembly 20 and the multi-channel telescopic drill rod 10 to rotate and cut the soil body for drilling. There are two normal drilling mud circulations: positive circulation and reverse circulation. In the positive circulation, the mud is ejected from the bottom of the drill rod, driving the drill cuttings to be transported upward along the outer side of the drill rod to the ground for precipitation, so as to realize the drilling and forming of holes. The positive circulation drill bit is easily wrapped by the soil body and is easy to get stuck. In the reverse circulation, mud flows from the outer mud pool into the hole, and at the bottom of the hole, the mud and drill cuttings are sucked to the ground through the middle channel of the drill pipe by a vacuum pump to complete the drilling. Since the reverse circulation process does not need to repeatedly crush the drill cuttings and directly suck the drill cuttings, its hole-forming efficiency is higher than that of the positive circulation. Its disadvantage is that the mud enters from the outer hole, which is easy to scour the hole wall, which is easy to cause the hole wall to be unstable and collapse. The drilling drill bit 30A in this embodiment is designed with a double channel, so a new mud circulation process can be adopted, which we call "reverse circulation". The mud circulation is input from the first channel of the drill pipe to the bottom of the drill bit. The drill bit cuts the soil, and the mud and drill cuttings mixture formed is directly sucked to the ground through the fluid inlet and outlet 30A-3 on the upper part of the drill bit and the second channel of the drill pipe by a vacuum pump. The hole-forming speed is fast, and at the same time, the mud is prevented from scouring the hole wall, which is easy to cause the hole wall to be unstable and collapse. In addition, when the "reverse circulation" process is not adopted, the fluid inlet and outlet 30A-3 at the lower spiral wing plate 30A-2 can be opened, and high-pressure gas can be sprayed from the bottom of the drill bit during reverse circulation drilling to assist in cutting the soil and prevent the soil from wrapping the drill bit and causing the drill to become stuck. In addition, during bored pile construction, after the hole is formed and the steel cage is lowered normally, the drilling drill bit 30A can be disassembled and the multi-channel telescopic drill rod 10 can be reinserted into the hole and used as a conduit, avoiding the installation and disassembly of the grouting conduit in a narrow space, thereby improving construction efficiency.

[0078] like Fig.12 and Fig.13As shown, the pile mixing drill bit 30B has a mixing drill tip 30B-1 and a plurality of mixing blades 30B-2 distributed on the side of the pile mixing drill bit 30B. The pile mixing drill bit 30B is also provided with at least two fluid nozzles 30B-3 arranged axially spaced and connected to the corresponding cavities. During the construction of the pile mixing, the pile mixing drill bit 30B is mainly driven by the power head assembly 20 and the multi-channel telescopic drill rod 10 to rotate and mix the soil. At the same time, the curing agent and gas are transported through the fluid nozzles 30B-3 through the multi-channel telescopic drill rod 10 and the multiple channels in the pile mixing drill bit 30B to mix with the soil to form a pile mixing body.

[0079] like Fig.14 and Fig.15 As shown, the high-pressure jet grouting drill head 30C has a jet grouting drill tip 30C-1 and at least one high-pressure nozzle 30C-2 connected to the corresponding tube cavity. During the construction of the high-pressure jet grouting pile, the high-pressure jet grouting drill head 30C is mainly driven to rotate by the power head assembly 20 and the multi-channel telescopic drill rod 10, and the soil is cut by the high-pressure curing agent fluid and gas. Through the multi-channel telescopic drill rod 10 and the multiple channels in the high-pressure jet grouting drill head 30C, the curing agent and gas are transported through the high-pressure nozzle 30C-2 and mixed with the soil to form the high-pressure jet grouting pile body.

[0080] like Fig.16 and Fig.17 As shown, the upper end of the threaded enlarged steel pile drill bit 30D is provided with a steel pile joint 30D-1, which is fixed to the lower end of the final telescopic rod body 13, and the steel pile joint 30D-1 and the threaded enlarged steel pile drill bit 30D are plugged in with a non-circular cross-section axial hole. For example, the steel pile joint 30D-1 and the threaded enlarged steel pile drill bit 30D can be plugged in with a non-circular cross-section axial hole such as a regular hexagon, so that torque transmission can be achieved and the threaded enlarged steel pile drill bit 30D can be easily separated after implantation. The threaded enlarged steel pile construction is mainly carried out by driving the threaded enlarged steel pile drill bit 30D to rotate and implant into the soil through the power head assembly 20 and the multi-channel telescopic drill rod 10, and then the multi-channel telescopic drill rod 10 is lifted and separated from the threaded enlarged steel pile drill bit 30D to form a threaded enlarged steel pile.

[0081] The multi-channel telescopic drill rod and multifunctional telescopic drill tool of the present invention can adapt to various geological conditions, improve construction efficiency, have automatic operation functions, and have a simple and reliable structure; the multifunctional telescopic drill tool realizes efficient and accurate construction operations in a limited space through integrated innovative design, while reducing the follow-up work during construction and improving the flexibility and adaptability of construction; through the application of the multifunctional telescopic drill tool, the construction quality of pile foundation engineering can be effectively improved, the construction period can be shortened, and the engineering cost can be reduced, thereby meeting the high standards of pile foundation construction in modern construction engineering. Specifically:

[0082] (1) To address the adaptability issues of conventional construction drilling tools: The multi-channel telescopic drill rod can be used with a variety of process drill bits, so that a variety of foundation construction processes can be completed on one pile driver, such as bored pile construction, mixing pile construction, high-pressure jet grouting pile construction, and threaded expanded steel pile construction, which improves the flexibility and adaptability of construction;

[0083] (2) To address the construction efficiency issues of conventional drilling tools: Multi-channel telescopic drill pipes can achieve multi-stage telescopic drill pipe extension without the need for connecting rods. In addition, the drill pipe can be telescopic at multiple stages and can also transport multiple fluids, effectively solving the problem of low construction efficiency caused by frequent replacement or adjustment of drilling tools.

[0084] (3) To address the problem of low automation of conventional drilling tools: a fully hydraulic power head is used to automatically control the multi-channel telescopic drill rod, so that there is no need to manually add drill rods. The automation level is high and the construction efficiency is also high. At the same time, due to the lack of connecting rod links, the deformation links are reduced, and the coordination between the telescopic drill rods is mutually nested and controlled, which improves the verticality and accuracy of the construction drill rods.

[0085] (4) Regarding the problems of complex structure and difficult maintenance of conventional drilling tools:

[0086] Since a mechanical screw is used to propel the telescopic drill rod and a dual-drive power head is used for propulsion, the mechanical structure is simple and maintenance is convenient.

[0087] The present invention and its embodiments are described schematically above, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and creatively designs a structure and an embodiment similar to the technical solution without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A multi-channel telescopic drill pipe, characterized in that: It includes a synchronous telescopic rod body part and a fluid channel part, wherein: The synchronous telescopic rod part comprises a primary fixed rod (11), an intermediate telescopic rod (12), a final telescopic rod (13), a primary screw (15) and an intermediate transmission screw (16); the primary fixed rod (11), the intermediate telescopic rod (12) and the final telescopic rod (13) are sleeved together step by step from outside to inside, and the telescopic rods of each stage are axially locked relative to the primary fixed rod (11); the primary screw (15) and the intermediate transmission screw (16) are arranged on the primary fixed rod (11), the intermediate telescopic rod (12) and the final telescopic rod (13) 3), and the primary screw (15) and the intermediate transmission screws (16) of each level are threadedly sleeved together from the inside to the outside; the intermediate transmission screws (16) of each level are relatively rotatably connected with the intermediate telescopic rod body (12) of the corresponding level through the annular relay (17), and the primary screw (15) and the intermediate transmission screws (16) of each level are threadedly matched with the corresponding intermediate telescopic rod body (12) of the next level and the final telescopic rod body (13); by driving the primary screw (15) to rotate, the telescopic rod bodies of each level are driven to synchronously axially telescopically move relative to the primary fixed rod body (11); The fluid channel portion comprises a fluid channel (15-1) provided on the primary screw (15), and a bellows expansion tube (18) provided between the lower end of the primary screw (15) and the lower end of the final expansion rod (13); the fluid channel (15-1) is provided with at least two channels from the inside to the outside on the primary screw (15); the upper end of the bellows expansion tube (18) is connected to the lower end of the primary screw (15) via a multi-channel rotary joint (18-1); and the bellows expansion tube (18) is formed from the inside to the outside of the ring to form tube channels corresponding to the fluid channels (15-1), and each tube channel is communicated with a corresponding channel opening (13-1) at the lower end of the final expansion rod (13).

2. The multi-channel telescopic drill rod according to claim 1, characterized in that: The first-stage fixed rod body (11), the intermediate telescopic rod body (12) and the final telescopic rod body (13) are all cylindrical structures, and anti-rotation guide ribs (14) are provided between the first-stage fixed rod body (11) and the adjacent intermediate telescopic rod body (12), between the intermediate telescopic rod bodies (12) of each stage, and between the final telescopic rod body (13) and the adjacent intermediate telescopic rod body (12).

3. The multi-channel telescopic drill rod according to claim 1, characterized in that: The upper ends of the intermediate transmission screws (16) of each level are provided with screw connecting parts (16-1), and the upper ends of the intermediate telescopic rods (12) of each level are provided with intermediate rod connecting parts (12-1). The screw connecting parts (16-1) are sleeved on the outer sides of the corresponding intermediate rod connecting parts (12-1), and the annular servomotor (17) is arranged between the corresponding screw connecting parts (16-1) and the intermediate rod connecting parts (12-1) to realize axial connection between the screw connecting parts (16-1) and the intermediate rod connecting parts (12-1) and enable relative rotation.

4. The multi-channel telescopic drill rod according to claim 3, characterized in that: The annular servomotor (17) is a circular ring structure.

5. The multi-channel telescopic drill rod according to claim 1, characterized in that: The primary screw (15) is a hollow screw, and the fluid channel (15-1) is composed of concentric tubes which are sleeved layer by layer on the inner side of the primary screw (15).

6. A multifunctional telescopic drilling tool, comprising a power head assembly (20) and a process drill bit (30), characterized in that: It also comprises the multi-channel telescopic drill rod (10) according to any one of claims 1 to 5, wherein the power head assembly (20) is connected to the process drill bit (30) through the multi-channel telescopic drill rod (10), wherein: The power head assembly (20) comprises a multi-channel flow divider (24), and an independently driven drill pipe rotary joint (25) and a screw drive joint (26); the multi-channel flow divider (24) is arranged at the upper end of the screw drive joint (26); the drill pipe rotary joint (25) is located outside the screw drive joint (26); the upper end of the primary fixed rod body (11) of the multi-channel telescopic drill pipe (10) is fixedly mounted on the drill pipe rotary joint (25); the upper end of the primary screw (15) of the multi-channel telescopic drill pipe (10) is fixedly mounted on the screw drive joint (26); and each fluid channel (15-1) on the primary screw (15) is respectively connected to a corresponding flow divider channel (24-3) in the multi-channel flow divider (24); The process drill bit (30) is mounted on the lower end of the final telescopic rod body (13) of the multi-channel telescopic drill rod (10), and the corresponding lumen in the process drill bit (30) is in communication with the corresponding channel opening (13-1) on the final telescopic rod body (13).

7. The multifunctional telescopic drilling tool according to claim 6, characterized in that: The power head assembly (20) further comprises a box (21), on the side walls of which a telescopic drive hydraulic motor (22) and a drill rod drive hydraulic motor (23) are respectively placed horizontally, the telescopic drive hydraulic motor (22) being connected to a screw drive joint (26) via a screw drive transmission mechanism (28), and the drill rod drive hydraulic motor (23) being connected to a drill rod rotary joint (25) via a drill rod drive transmission mechanism (27).

8. The multifunctional telescopic drilling tool according to claim 7, characterized in that: The drill rod drive transmission mechanism (27) and the screw drive transmission mechanism (28) both adopt planetary gear reduction mechanisms.

9. The multifunctional telescopic drilling tool according to claim 7, characterized in that: The screw drive joint (26) is a hollow rotating shaft, the upper end of which protrudes out of the box body (21). The multi-channel flow divider (24) comprises a rotary flow divider seat (24-1) and a channel tube (24-2). The channel tube (24-2) is sleeved on the inner side of the screw drive joint (26) to form a concentric annular distribution of flow divider channels (24-3). The rotary flow divider seat (24-1) is rotatably mounted on the upper end of the screw drive joint (26). The rotary flow divider seat (24-1) is provided with a pipe joint connected to the corresponding flow divider channel (24-3).

10. The multifunctional telescopic drilling tool according to any one of claims 6 to 9, characterized in that: The process drill bit (30) comprises one of a drilling drill bit (30A), a mixing pile drill bit (30B), a high-pressure jetting drill bit (30C) and a thread-enlarged steel pile drill bit (30D), wherein: The drilling drill bit (30A) comprises a drilling drill tip (30A-1) and a plurality of spiral wing plates (30A-2) located on the upper portion of the drilling drill tip (30A-1); the drilling drill bit (30A) is also provided with at least two fluid inlets and outlets (30A-3) which are axially spaced and communicated with corresponding lumens; the fluid inlets and outlets (30A-3) are matched with plugs (30A-4); and different drilling circulation processes are formed by plugging different fluid inlets and outlets (30A-3); The mixing pile drill bit (30B) comprises a mixing drill tip (30B-1) and a plurality of mixing blades (30B-2) distributed on the side of the mixing pile drill bit (30B); the mixing pile drill bit (30B) is also provided with at least two fluid nozzles (30B-3) which are axially spaced and connected to corresponding lumens; The high-pressure jet grouting drill bit (30C) comprises a jet grouting drill tip (30C-1) and at least one high-pressure nozzle (30C-2) connected to a corresponding lumen; The upper end of the threaded enlarged steel pile drill bit (30D) is provided with a steel pile joint (30D-1), and the steel pile joint (30D-1) is fixed to the lower end of the final telescopic rod body (13). The steel pile joint (30D-1) and the threaded enlarged steel pile drill bit (30D) are plug-fitted with a non-circular cross-section axial hole.

Images