A pile body expanding multifunctional double-power drilling device, a preparation method and a pile

Abstract

The present application relates to the civil engineering technical field, especially to a pile body expanding multifunctional double-power drilling device, a preparation method and a pile. The pile body expanding multifunctional double-power drilling device comprises: an upper power drilling device and a lower power drilling device; the upper power drilling device comprises: an upper power mechanism and a central mixing hammer; the central mixing hammer can rotate in linkage under the driving of the upper power mechanism, and can make axial lifting action under the driving of a winch; the lower power drilling device comprises: a lower power mechanism and a lower sleeve drilling device; the lower sleeve drilling device can rotate in linkage under the driving of the lower power mechanism; the lower power mechanism is provided with two feeding ports, one feeding port is used for conveying super-fluidity concrete, and the other feeding port is used for conveying dry cement mixture. Through the cooperation of the double-power drilling device, the ramming and expanding dry concrete realizes the pile body expansion, the pile end expansion (enlarged head), and the super-fluidity concrete / ramming dry concrete forms the pile body main body.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a multifunctional dual-power drilling tool for pile diameter expansion, its preparation method, and the type of pile. Background Technology

[0002] In soft soil foundation treatment for building structures, bridges, ports, railways, highways, airports, and water conservancy and hydropower facilities, bored pressure grouting piles and rammed piles are generally used to improve the bearing capacity of the foundation soil and reduce its settlement. Among them, the bored pressure grouting pile process: its original theoretical basis is that regardless of the soil properties, the foundation is treated by removing soil to form a hole, and then replacing the soil with piles to create a composite foundation or pile foundation. The full name of this process is long spiral bored pressure grouting pile—CFG pile. In recent years, several innovative technologies have been developed based on the long spiral bored grouting pile—CFG pile: A high-pressure injection cement grout device is added to the traditional long spiral bored grouting pile drilling tool to increase the diameter of the CFG pile (CN02132652.5, CN201210159584.8, CN201810087422.5); In some displacement methods, screw piles or threaded piles (CN201810254578.8, CN202010073505.6) use a support and expansion device (jacking device) added to the bottom of the drilling tool to achieve diameter expansion, or after grouting concrete at specific pile locations, re-driving and re-grouting are performed, applying a squeezing force to the concrete through the drilling tool to produce a diameter expansion effect. These innovative pile diameter expansion technologies have increased the single pile bearing capacity and reduced pile settlement to varying degrees. Shortcomings: The expansion body formed by the high-pressure injection cement slurry device and the expansion device (jacking device) on the drilling tool is a cavity formed by cutting, which causes a loss of the compaction of the soil around the cavity, especially the soil on the upper side of the free space; the screw pile adopts the positioning and re-driving and re-pouring concrete technology, which produces a limited expansion effect. It is limited by the pressure and torque of the drilling tool and the super-fluid concrete, and cannot generate a large energy impact force to squeeze and expand the soil around the pile.

[0003] Among them, the rammed and expanded pile technology includes pile hammer punching to expand the hole, and then ramming and filling cement mixture, lime-soil, sand and gravel in stages to form piles. This type of rammed and expanded pile has improved the bearing capacity of composite foundations to varying degrees. However, the technology is limited by the strata. It is suitable for treating foundations such as miscellaneous fill, silt, cohesive soil, plain fill and loess above the groundwater level. The depth of the foundation should not exceed 10m. It is not applicable to engineering sites with rich geological water content and high water level. Moreover, even if it is applied in suitable strata, the bearing capacity of a single pile is not high, and the improvement of the bearing capacity of composite foundations is also limited. Generally, it will not exceed twice the bearing capacity of the natural foundation and will not exceed the characteristic value of 250kPa.

[0004] Another type of carrier pile technology, developed in the last 20 years (CN98101041.5, CN200410102711.6, CN201610090411.3), involves hammering with a casing to form the hole. At a certain depth, a relatively stable stratum with good soil properties is selected. Construction waste, cement mixtures, and dry-hardened concrete are compacted in batches to maximize the expansion and compaction of the bearing stratum at the pile tip. Simultaneously, a bearing sphere with an axial and radial diameter of not less than 1.5 times the pile diameter is artificially created. This effectively increases the load-bearing area at the pile tip, enhancing the bearing capacity of the bearing stratum and thus improving the single pile's bearing capacity. The carrier pile technology is mostly applicable to foundation piles in pile foundations, with bearing characteristics of end-bearing piles or friction-end-bearing piles. The design and construction of carrier piles are also limited by pile length and soil strata. Carrier piles are typically around ten meters long, and within this depth, stable strata with relatively good soil properties are found for carrier implantation. For some strata with shallow tops, thicker layers, unconsolidated soft clay, collapsible loess, or soil layers generating negative skin friction, the pile length must penetrate a reasonable depth through these soil layers. The pile tip must be located in a structurally stable layer with low compressibility, high bearing capacity, and a layer thickness that meets the requirements of the bearing stratum to ensure the specifications for pile bearing capacity and deformation. Limited by the maximum pile length, the soil depth requirements cannot be met, thus restricting the applicability of carrier piles to a certain extent. Carrier pile extension process: Prestressed concrete pipe piles are connected to carrier piles. After the prestressed concrete pipe pile penetrates to the designed depth, the carrier is implanted at the pile tip through the inner core of the prestressed concrete pipe pile, which similarly improves the single pile bearing capacity of the prestressed concrete pipe pile. The combination of prestressed pipe pile core carrier pile and other two pile technologies compensates for the limitations of pile length and selection of better bearing layer, but the integration process is too complicated, resulting in high construction costs.

[0005] Enlarged diameter and enlarged base cast-in-place piles (CN202210183452.2) fully exploit the bearing potential of the soil with good properties at the pile bottom and around the pile body, and improve the bearing capacity of a single pile. However, they still have shortcomings such as inconsistent implementation of construction processes and low efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-functional dual-power drilling tool for pile diameter expansion, a preparation method, and a pile profile, so as to solve the technical problems existing in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a multi-functional dual-power drilling tool for pile diameter expansion, comprising: an upper power drilling tool and a lower power drilling tool; the upper power drilling tool includes: an upper power mechanism and a central stirring hammer; the upper power mechanism is provided with an upper power reducing joint, which is provided with a driving regular polygonal hole; the central stirring hammer is structurally divided into upper and lower parts, the upper part being a solid long cylinder with a regular polygonal cross-section, and the lower part being a solid cylinder with a threaded blade structure; the long cylinder axially passes through the driving regular polygonal hole of the upper power reducing joint, and the top of the long cylinder is connected to a winch; the central stirring hammer can rotate in conjunction with the upper power mechanism, and simultaneously can act as a shaft under the drive of the winch. The system includes a lower power drill bit, comprising a lower power mechanism and a lower sleeve drill bit. The lower power mechanism is equipped with a lower power reducing joint. The lower sleeve drill bit consists of a hollow drill rod and a telescopic drill bit. The top of the drill rod of the lower sleeve drill bit is fixedly connected to the lower power reducing joint, and the bottom of the drill rod of the lower sleeve drill bit is connected to the telescopic drill bit. The lower power mechanism has two feed ports, one for conveying superfluid concrete and the other for conveying dry cement mixture. A central mixing hammer is fitted into the hollow drill rod of the lower sleeve drill bit. The upper and lower power mechanisms are rigidly connected by a connecting rod. The lower sleeve drill bit can rotate in conjunction with the lower power mechanism.

[0009] Preferably, two upper connection points are provided on the symmetrical sides of the upper end of the upper power mechanism; the upper connection points of the upper power mechanism are connected to the wire rope of the first winch; an upper connection point is provided at the top of the central stirring hammer; the upper connection point of the central stirring hammer is connected to the wire rope of the second winch through a lifting device.

[0010] Preferably, the upper power mechanism has two lower connection points on its symmetrical sides at the lower end; the lower power mechanism has two upper connection points on its symmetrical sides at the upper end; the lower connection points of the upper power mechanism and the upper connection points of the lower power mechanism are rigidly connected; at the same time, both the upper and lower power mechanisms can be slidably installed on the slide of the drilling rig tower by means of slips.

[0011] Preferably, one inlet of the lower power mechanism is connected to a concrete pump for conveying superfluid concrete; the other inlet of the lower power mechanism is connected to an anchor spraying device for conveying dry cement mixture.

[0012] Preferably, the telescopic drill bit includes: a drill bit outer sleeve and an inner drill core; the upper end of the drill bit outer sleeve is provided with a hexagonal female connector; the lower end of the drill bit outer sleeve is provided with a hexagonal limiting sleeve; the inner drill core is telescopically installed on the drill bit outer sleeve; the top of the inner drill core is provided with a hexagonal limiting sleeve; the periphery of the inner drill core is provided with a discharge hole; the bottom of the inner drill core is provided with an opening and closing door structure or not provided with an opening and closing door structure. Preferably, the drill rod of the lower sleeve drill bit has a structure with full squeezing / partial squeezing / soil discharge functions.

[0013] This invention provides a pile preparation method using a multifunctional dual-power drilling tool for pile diameter enlargement, comprising: a pile body and an enlarger; the pile body is a straight rod structure; the surface of the pile body is a smooth rod without threads, or entirely or partially threaded; at least one enlarger is provided on the pile body; the enlarger is divided into a non-connected enlarger and a connected enlarger; the shape of the enlarger includes any one of spherical, elliptical, or gourd-shaped; the gourd-shaped enlarger is designed on the pile body in an inverted or upright manner. The pile body is made of superfluid concrete / dry-hard concrete; the enlarger is made of dry-hard concrete.

[0014] This invention provides a method for preparing shaped piles using a multi-functional dual-power drilling tool for pile diameter expansion. When the expansion is performed from top to bottom, the process includes: the lower power drill bit displacing / partially displacing soil to the designed depth of the first expansion section and stopping drilling; the upper power drill bit simultaneously mixing and downward-rotating dry-hard concrete while re-compacting; the dry-hard concrete is gradually extruded from the discharge hole, gradually expanding the pile diameter until the required density is achieved and the expansion is complete; the lower power drill bit continues displacing / partially displacing soil to the next designed depth of the expansion section, repeating the expansion process until the pile end expansion is complete; then, with the assistance of the upper power drill bit's rotary discharge function, super-fluid concrete is simultaneously poured while the lower power drill bit is raised until the pouring reaches the pile top elevation, completing the process of creating a variable-diameter pile with the expanded diameter. The dry-hard concrete used for the expansion is a mixture of super-fluid concrete and dry cement in the designed mass ratio, remixed and stirred by the upper power drill bit.

[0015] This invention provides a method for preparing shaped piles using a multifunctional dual-power drilling tool for pile diameter expansion. The method includes expanding the pile diameter from bottom to top, comprising: the lower power drill bit drilling to the designed depth at the pile tip by squeezing / partially squeezing / discharging soil; the upper power drill bit simultaneously mixing and downwardly rotating dry-hard concrete while compacting; the dry-hard concrete is gradually squeezed out from the discharge hole, gradually expanding the pile diameter until the required density is achieved; the pile tip expansion body or N consecutive expansion bodies are formed by compaction; then, with the assistance of the upper power drill bit's rotational discharge function, super-fluid concrete is simultaneously poured while the lower power drill bit is raised until the concrete is poured to the pile top elevation, completing the transformation of the pile body with the expanded diameter; (the following steps are suitable for soil squeezing / discharging methods for hole formation). After the pile tip expansion body or N consecutive expansion bodies are formed, dry-hard concrete is filled while lightly compacting... The pile body is constructed by raising the power drill bit while ramming and expanding the pile body until the designed depth of the previous expansion body is reached. The ramming and expansion of the pile body is repeated until all the expansion bodies of the pile body are completed. Then, while filling with dry-hard concrete, the pile body is lightly rammed and expanded, and the power drill bit is raised simultaneously until it is rammed to the top elevation of the pile. The pile body with the expansion body is now complete. Alternatively, if there are no more expansion bodies after 1 to N expansion bodies are completed, the main body material of the pile body can be super-fluid concrete. With the assistance of the rotary drilling function of the power drill bit, the pressure grouting process is carried out until the top elevation of the pile body is reached. The pile body with the expansion body is now complete. The dry-hard concrete is the material used for ramming and expanding the pile body. It is made by re-mixing and stirring super-fluid concrete and dry cement mixture according to the design mass ratio by the power drill bit.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects:

[0017] This invention revolutionizes the traditional drilling and tamping process for expanded-diameter piles, overcoming its shortcomings and making it applicable to a wider range of geological formations with higher single-pile bearing capacity. It also simplifies and speeds up construction, significantly increasing automation and reducing manual labor. In particular, it generates dry-hardened concrete within the drill core, indirectly solving a global industry challenge—the inability of concrete pumps to deliver dry-hardened concrete. This solution represents a revolutionary advancement in the long-auger drilling and pressure grouting pile (CFG pile) process and its extension processes (threaded piles, screw piles, SDS piles), enabling the tamping of dry-hardened concrete and making it possible to substantially increase the single-pile bearing capacity—through tamping and expanding the diameter of the pile. The hammering function, combined with the application of telescopic drilling tools, assists drilling, making integrated drilling and pressure grouting construction in complex and difficult-to-drill formations no longer a challenge but a readily applicable solution. The invention of these technologies has solved the bottleneck of industry technology development and is destined to be widely used due to industry needs and development. These technologies have not only greatly and effectively improved the bearing capacity of single piles but also increased work efficiency, comprehensively improved the economic cost-effectiveness, and promoted the progress of industry technology. In the future, the application of innovative technologies will break down the barriers that hinder the integration between different pile forming processes, promote the integration of their respective process advantages, and ensure that the rammed and expanded pile process and the bored pressure grouting pile process are combined into one, achieving 1+1>2. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A structural comparison diagram of the initial and ramming / expansion states of the multifunctional dual-power drill bit provided in an embodiment of the present invention; Figure 2 A frontal view comparing the initial and ramming / expansion states of the drilling rig and the multi-functional dual-power drilling tool provided in an embodiment of the present invention. Figure 3 A comparative structural diagram of the front and side of the upper power drill bit provided in an embodiment of the present invention; Figure 4 This is a structural comparison diagram of the top view of the upper power mechanism provided in an embodiment of the present invention; Figure 5 This is a structural schematic diagram of the central stirring hammer provided in an embodiment of the present invention; Figure 6 A comparative structural diagram of the front and side of the down-powered drilling tool (soil removal drilling tool) provided in an embodiment of the present invention; Figure 7 A comparative structural diagram of the front and side of the down-powered drilling tool (partial soil squeezing function - threaded blade soil squeezing drilling tool) provided in an embodiment of the present invention; Figure 8A comparative structural diagram of the front and side of the power drill bit (full soil displacement function - a soil displacement and discharge drill bit mainly for displacement) provided in an embodiment of the present invention; Figure 9 A schematic diagram of the structure of a telescopic drill bit (split type) for a lower sleeve drilling tool—a soil removal drilling tool—provided in an embodiment of the present invention; Figure 10 A schematic diagram of the structure of a special telescopic drill bit (split type) for a lower sleeve drilling tool—a threaded blade soil squeezing drilling tool—provided in an embodiment of the present invention; Figure 11 A schematic diagram of the structure of a special telescopic drill bit (split type) for a soil extrusion drilling tool with a lower sleeve provided in an embodiment of the present invention; Figure 12 A schematic diagram of the structure of a telescopic drill bit (integrated type) for a lower sleeve drilling tool and a soil removal drilling tool provided in an embodiment of the present invention; Figure 13 A schematic diagram of the structure of a telescopic drill bit (integrated type) for a lower sleeve drilling tool—a threaded blade soil squeezing drilling tool—provided in an embodiment of the present invention; Figure 14 A schematic diagram of the structure of a telescopic drill bit (integrated type) for a soil extrusion drilling tool with a lower sleeve provided in an embodiment of the present invention. Figures 15 to 18 The invention provides a process for preparing a threaded blade soil-displacing drill bit, which partially displaces soil to form a hole, and then rams dry hard concrete from top to bottom to form an enlarged diameter body, followed by pressure grouting of concrete to form a pile. Figure 15 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention; Figure 16 A schematic diagram of the working state of the threaded blade soil squeezing drill bit provided in this embodiment of the invention, which drills to the designed depth of the pile body expansion body and quantitatively fills the pile body material—dry hard concrete—with a heavy hammer to expand and form the expansion body. Figure 17 This is a schematic diagram of the working state of the pile body after the pile body is filled with dry hard concrete at the designed depth of the lower diameter body of the pile body and the pile end is formed by hammer tamping. The diagram shows the working state of the pile end diameter body after the lower power drill bit drills to the designed depth of the pile end and quantitatively feeds the material to form the pile end diameter body by hammer tamping. Figure 18 This is a schematic diagram of the working state of the pile body pressure grouting completed, provided by an embodiment of the present invention, showing the simultaneous grouting of concrete and the raising of the lower power drilling tool to the pile top elevation. Figures 19 to 22 The present invention provides a process for preparing a soil extrusion drilling tool that primarily uses extrusion to form a hole, followed by ramming and expanding the diameter with dry, hard concrete from top to bottom, and then grouting concrete to form a pile. Figure 19 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention;

[0020] Figure 20 This is a schematic diagram of the working state of a soil-expanding drilling tool that primarily uses extrusion to drill to the designed depth of the pile body expansion body and quantitatively fill the pile body material—dry-hard concrete—with a heavy hammer to expand the pile body into an expanded diameter body, as provided in an embodiment of the present invention.

[0021] Figure 21This is a schematic diagram of the working state of the pile body after the pile body is filled with dry hard concrete at the designed depth of the lower diameter body of the pile body and the pile end is formed by hammer tamping. The diagram shows the working state of the pile end diameter body after the lower power drill bit drills to the designed depth of the pile end and quantitatively feeds the material to form the pile end diameter body by hammer tamping. Figure 22 This is a schematic diagram of the working state of the pile body pressure grouting completed, provided by an embodiment of the present invention, showing the simultaneous pressure grouting of concrete and the lifting of the lower power drilling tool to the pile top elevation. Figures 23 to 26 The present invention provides a process for preparing a pile by using a conventional long spiral drill for soil removal and hole formation, and for expanding the diameter of the pile by compacting dry hard concrete from bottom to top. Figure 23 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention; Figure 24 This is a schematic diagram of the working state of the pile end enlargement body formed by the down-powered drilling tool drilling to the designed depth of the pile end and quantitatively filling the pile body material—dry hard concrete—with heavy hammer tamping. Figure 25 This is a schematic diagram of the working state of the pile body formed by the power drilling tool under the light hammer tamping and lifting of the dry hard concrete pile material provided in the embodiment of the present invention.

[0022] Figure 26 This is a schematic diagram illustrating the working state of the pile body tamping and filling process provided in this embodiment of the invention, which involves using a power drill to repeatedly expand the diameter of the pile body and the main body of the pile body until the top elevation of the pile is reached. Figures 27 to 30 The present invention provides a process for preparing a soil-expanding drilling tool that primarily uses extrusion to form holes, followed by bottom-up compaction and expansion of dry, hard concrete to form piles. Figure 27 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention; Figure 28 This is a schematic diagram of the working state of the pile end enlargement body formed by the down-powered drilling tool drilling to the designed depth of the pile end and quantitatively filling the pile body material—dry hard concrete—with heavy hammer tamping. Figure 29 This is a schematic diagram of the working state of the pile body formed by the power drilling tool under the light hammer tamping and lifting of the dry hard concrete pile material provided in the embodiment of the present invention. Figure 30 This is a schematic diagram illustrating the working state of the pile body tamping and filling process provided in this embodiment of the invention, which involves using a power drill to repeatedly expand the diameter of the pile body and the main body of the pile body until the top elevation of the pile is reached. Figures 31 to 33 The present invention provides a process for preparing a pile by using a conventional long spiral drill to form a hole for soil removal, followed by continuous diameter expansion of the pile end with dry hard concrete and then pressure grouting concrete. Figure 31 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention; Figure 32The diagram illustrates the working state of the lower power drill bit drilling to the designed depth of the pile end, the pile end being quantitatively filled with pile material—dry hard concrete—and then being tamped by a heavy hammer to form an enlarged diameter body. The lower power drill bit is then raised twice to an appropriate height to quantitatively add material and tamped by a heavy hammer to form a gourd-shaped connected enlarged diameter body. Figure 33 This is a schematic diagram of the working state of the pile body pressure grouting completed, provided by an embodiment of the present invention, showing the simultaneous grouting of concrete and the raising of the lower power drilling tool to the pile top elevation. Figures 34 to 36 The present invention provides a process for preparing a soil-draining drilling tool that primarily uses extrusion to form a hole, followed by continuous diameter expansion of the pile end with dry-hard concrete and subsequent pressure grouting of concrete to form a pile. Figure 34 This is a schematic diagram of the working state of the dual-power drilling tool aligned with the pile position according to an embodiment of the present invention; Figure 35 The diagram illustrates the working state of the lower power drill bit drilling to the designed depth of the pile end, the pile end being quantitatively filled with pile material—dry hard concrete—and then being tamped by a heavy hammer to form an enlarged diameter body. The lower power drill bit is then raised twice to an appropriate height to quantitatively add material and tamped by a heavy hammer to form a gourd-shaped connected enlarged diameter body. Figure 36 This is a schematic diagram of the working state of the pile body pressure grouting completed, provided by an embodiment of the present invention, showing the simultaneous grouting of concrete and the raising of the lower power drilling tool to the pile top elevation.

[0023] Figures 37 to 40 This is a schematic diagram of pile types matching different site soils and bearing properties, provided in an embodiment of the present invention. Figure 37 The pile end depth distribution provided in this embodiment of the invention includes a stable soil layer with good soil properties, and the upper soil layer consists of under-consolidated soft clay, newly filled soil, etc., which has negative skin friction and is suitable for bearing characteristics: schematic diagram of end-bearing pile; Figure 38 The pile tip depth distribution provided in this embodiment of the invention includes stable soil layers with good soil properties, while the soil properties of the upper soil layers are generally good. The lower part of the soil around the pile also includes stable soil layers with good soil properties, while the soil properties of the upper soil layers are generally good. Suitable bearing characteristics: Schematic diagram of friction end bearing pile. Figure 39 The upper part of the soil around the pile provided in the embodiment of the present invention has a stable soil layer with good soil properties, while the lower part has general soil properties and is suitable for bearing characteristics: the original friction pile is transformed into a friction end bearing pile after the pile body is enlarged. Figure 40 The soil distribution pattern around the pile provided in the embodiment of the present invention is that the soil gradually changes from soft to hard or the soil properties are uniform from top to bottom, which is suitable for bearing characteristics: the original end-bearing friction pile or friction pile is transformed into a friction end-bearing pile after the pile body is enlarged. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] Combination Figures 1 to 40 As shown, this embodiment provides a multi-functional dual-power drilling tool for pile diameter expansion, which includes: an upper power drilling tool 1 and a lower power drilling tool 2; the upper power drilling tool 1 includes: an upper power mechanism 11 and a central stirring hammer 12; the upper power mechanism 11 is provided with an upper power reducing connector 111 (the main structure of the upper power mechanism can use the existing structure on the market, and the upper power reducing connector can be fixed with the drive disc screw of the power mechanism), the upper power reducing connector 111 is provided with a driving regular polygonal hole 1111, the central stirring hammer 12 is divided into upper and lower parts according to its structural form, the upper part is a solid long cylinder 121 with a regular polygonal cross-section, and the lower part is a solid cylinder 122 with a threaded blade structure; the long cylinder 121 shaft The drive polygonal hole 1111 passes through the upper power reducer 111, and the top of the long column 121 is connected to the winch. The central stirring hammer 12 can rotate in conjunction with the upper power mechanism 11, and can also perform axial lifting and lowering movements under the drive of the winch. Therefore, when the upper power mechanism 11 only rotates without performing axial lifting and lowering movements, the central stirring hammer 12 can rotate in conjunction with the lower power drill 2 and perform axial lifting and lowering movements at the same time, so that the pile material in the core tube of the lower power drill 2 can be stirred, rotated downward, and tamped / untamped simultaneously. When the lower power drill 2 is drilling, if it encounters complex and difficult drilling strata, the central stirring hammer 12 can perform hammering work on the drill bit to assist drilling (applicable to telescopic drill bit 222). The lower power drill 2 includes a lower power mechanism 21 and a lower sleeve drill 22. The lower power mechanism 21 is equipped with a lower power reducing joint. The lower sleeve drill 22 consists of a hollow drill rod 221 and a telescopic drill bit 222. The top of the drill rod 221 of the lower sleeve drill 22 is fixedly connected to the lower power reducing joint, and the bottom of the drill rod 221 of the lower sleeve drill 22 is connected to the telescopic drill bit 222. The lower power mechanism 21 is equipped with two feed ports. One feed port is used to transport super-fluid concrete, and the other feed port is used to transport dry cement mixture. Therefore, when the lower power drill 2 drills to the designed depth, with the assistance of the upper power drill 1, the above-mentioned pile material is expanded through the discharge hole on the drill bit of the lower power drill 2 to form an expanded diameter body 32 / the pile hole for pressure grouting forms the main body of the pile 31 / the pile hole for ramming filling forms the main body of the pile 31.

[0027] In this embodiment, preferably, two upper connection points are provided on the symmetrical sides of the upper end of the upper power mechanism 11; the upper connection points of the upper power mechanism 11 are connected to the wire rope of the first winch; an upper connection point is provided at the top of the central stirring hammer 12; the upper connection point of the central stirring hammer 12 is connected to the wire rope of the second winch through the lifting device 123. The function of the lifting device 123 is to prevent the wire rope from twisting, coiling, or breaking during operation, and to offset the torque transmission generated by the rotation of the drill bit through its own rotation. The length of the central mixing hammer 12 is greater than that of the lower power drill 2. The specific parameters of the mass of the central mixing hammer 12, the diameter of the bottom end face of the cylinder 122, and the stroke of the axial lifting action are based on the technical parameters of the "Design Code for Carrier Piles" JGJ 135—2007: hammer diameter 355mm, mass 3500kg, drop distance 6.0m. The unit pressure of the impact force during hammer tamping is calculated, and the mass, structural specifications and dimensions of the central mixing hammer 12 are designed and manufactured. The purpose is that as long as the unit pressure of the impact force is the same for different central mixing hammers 12, the compaction standard of the expanded body during tamping can be implemented with reference to the three-blow penetration of the carrier pile.

[0028] Specifically, the upper part of the central mixing hammer 12 has a cross-section of a regular polygonal long cylinder 121, which can be a regular quadrilateral, regular pentagon, or regular hexagon. The lower part of the central mixing hammer 12 has a cylindrical structure with threaded blades around its periphery. These are ordinary threaded blades, and the blade pitch can be the commonly used screw diameter ratio for soil discharge drilling tools. (Screw diameter ratio: the ratio of the vertical spacing of the threaded blades to the diameter of the drilling tool, such as the commonly used screw diameter ratio (0.50~0.90)). When the threaded structure rotates, it mixes the pile material inside the core tube of the lower power drill tool 2 and rotates it to the bottom of the core tube. The bottom end of the cylinder 122 is a plane / an inverted frustum (which is beneficial for the squeezing and expanding effect) / an inverted cone (which is beneficial for the squeezing and expanding effect). This is conducive to the compaction, squeezing and expanding, and squeezing out the pile material at the bottom of the core tube of the lower power drill tool 2—dry hard concrete—to form a dense expanded diameter body. At the same time, the density of the soil around the expanded diameter body is also enhanced to a certain extent.

[0029] In this embodiment, preferably, two lower connection points are symmetrically arranged on both sides of the lower end of the upper power mechanism 11; two upper connection points are symmetrically arranged on both sides of the upper end of the lower power mechanism 21; the lower connection points of the upper power mechanism 11 and the upper connection points of the lower power mechanism 21 are rigidly connected to ensure that the lower power mechanism 21 and the upper power mechanism 11 move synchronously; at the same time, both the upper power mechanism 11 and the lower power mechanism 21 can be slidably installed on the slide rail of the drilling rig tower by means of slips. In this embodiment, preferably, one inlet of the lower power mechanism 21 is connected to a concrete conveying pump for conveying superfluid concrete; the other inlet of the lower power mechanism 21 is connected to an anchor spraying device for conveying dry cement mixture.

[0030] In this embodiment, preferably, the telescopic drill bit 222 includes: a drill bit outer sleeve 2221 and an inner drill core 2222; the upper end of the drill bit outer sleeve 2221 is provided with a hexagonal female connector end; the lower end of the drill bit outer sleeve 2221 is provided with an outer sleeve limiting hexagon; the inner drill core 2222 is telescopically installed on the drill bit outer sleeve 2221; the top of the inner drill core 2222 is provided with an inner drill core 2222 limiting hexagon; the periphery of the inner drill core 2222 is provided with a discharge hole; the bottom of the inner drill core 2222 is provided with an opening structure or is not provided with an opening structure. In practical applications, to ensure the normal function of the telescopic drill bit 222, an inner core protector 2223 is added inside the inner core 2222 to prevent pile material from entering the telescopic space of the inner core 2222 and affecting normal operation. There are two ways to add the inner core protector 2223, each with its advantages. The first is a split type. In the original telescopic drill bit assembly, the outer diameter of the normal male hexagonal connector structure is radially reduced by a certain amount, while the inner diameter remains unchanged, and the axial length is extended by a certain length. The bottom end is flush with the lower end of the outer sleeve limit hexagon of the drill bit outer sleeve 2221, thus realizing the inner core 2222... The telescopic movement takes place in a relatively enclosed space formed by the drill bit outer sleeve 2221 and the drill bit inner core 2223. The above-mentioned drill bit components are separate structures, and they only have the telescopic function when they are combined together. The second type is an integrated type, with the components of the telescopic drill bit 222: the drill bit outer sleeve 2221, the inner core 2222, and the drill bit inner core 2223. The top outer wall of the drill bit inner core 2223 is welded and fixed to the bottom of the hexagonal connector (female end) of the drill bit outer sleeve 2221. The inner core 2222 is sandwiched in it and can perform telescopic movements in the upper and lower limit spaces. The three components form a whole.

[0031] Specific applications of drill bits: Drill bits with suitable functions are matched according to the construction process, drilling difficulty, and density of the pile bearing stratum; pile diameter expansion proceeds from top to bottom, applicable drill bit types: telescopic drill bit 222 with discharge holes on the periphery / telescopic drill bit 222 with discharge holes on both the periphery and bottom of the drill bit and an openable door; for telescopic drill bit 222 with discharge holes only on the periphery, during pressure grouting and lifting of the drill bit, a pre-drilling depth is used to retract the drill bit, radially increasing the core space within the expanded diameter body or increasing the threaded space to connect with the original core space within the expanded diameter body. This facilitates timely filling of the space with concrete during pressure grouting and lifting of the drill bit, preventing a vacuum from forming within the core space of the expanded diameter body during pressure grouting and lifting, which could damage the expanded diameter body during hard lifting of the drill bit. The compaction of the drill bit produces a relaxation effect. This type of drill bit is suitable for pile end bearing strata with dense or high compression modulus. The bottom of the central mixing hammer has an inverted frustum structure, which is beneficial for radial expansion. The telescopic drill bit 222, which has discharge holes and an openable door on the periphery and bottom of the drill bit, is suitable for pile end bearing strata with less dense or less high compression modulus. The bottom of the central mixing hammer is flat. When expanding the diameter, the bottom of the hammer is kept flush with the top of the peripheral discharge hole. When expanding the bottom, the bottom of the hammer is kept horizontal and flush with the bottom discharge hole. The bottom of the peripheral discharge hole and the bottom discharge hole are designed with a certain axial distance. When the central mixing hammer applies an axial vertical force to expand the bottom, the side wall of the core tube gives a certain lateral constraint force to the expanded material, which strengthens the vertical expansion effect.

[0032] The pile diameter is expanded from bottom to top. Applicable drill bit types: ordinary drill bit (with discharge hole and opening / closing gate at the bottom) / telescopic drill bit 222 (no discharge hole on the periphery, discharge hole and opening / closing gate at the bottom). The bearing layer at the pile end is either dense or not. When expanding the diameter, the focus is on increasing the radial diameter of the expanded body. For dense layers, the focus is on increasing the density of the bearing layer. Conversely, the focus is on strengthening the compaction of the bearing layer to maximize its end bearing capacity. When the upper power drill bit 1 assists the lower power drill bit 2 in drilling, the drill bits are all telescopic, which is conducive to the concentration of impact kinetic energy, effectively assists drilling, and achieves efficient hole formation.

[0033] In this embodiment, preferably, the drill rod 221 of the lower sleeve drill bit 22 has a structure with soil removal / partial squeezing / full squeezing functions. Specifically, the drill rod 221 adopts a structure of soil removal using a long spiral ordinary drill rod, a partial soil squeezing type using a threaded blade soil squeezing drill rod that forms a threaded pile, or a soil squeezing and removal drill rod structure with squeezing as the main function. For the drill rod 221 with the partial soil squeezing type threaded blade soil squeezing drill rod structure or the soil squeezing and removal drill rod structure with squeezing as the main function, both types of drill rods have a pressure device 213 to assist drilling during hole formation. Among them, the ramming and expansion process is implemented from top to bottom, and the drill rod 221... 21 (Soil displacement drill rod primarily for extrusion / threaded blade soil displacement drill rod for forming threaded piles, with two pile materials—dry-hard concrete for the enlarged body and super-fluid concrete for the main pile body), equipped with a drill bit with telescopic function and discharge holes on the periphery / telescopic drill bit with discharge holes on the periphery and bottom of the drill bit and an openable door (Note: For soil displacement drills primarily for extrusion, the height of the enlarged body is greater than the length of the soil displacement ratio variation section of the drill bit to prevent the relaxation effect of the enlarged body; the length of the soil displacement ratio variation section is...) The shorter the displacement radius, the closer to or closer to the original location. ); Among them, the ramming and expansion process is implemented from bottom to top, and the drill rod 221 (squeezing and discharging drill rod mainly for extrusion / long spiral ordinary drill rod, the pile material is one type—dry hard concrete / the pile material is two types—dry hard concrete and super-fluid concrete, the pile body material between the expansion body and the pile body above the expansion body is dry hard concrete, or the pile body material above is super-fluid concrete) has a discharge hole at the bottom of the drill bit and an openable / closable... A standard long spiral drill bit; (a screw blade soil-displacing drill rod for forming a screw pile, only suitable for pile end tamping and diameter expansion, the pile body material is of two types - the expansion body material is dry hard concrete, and the main body material of the pile is super-fluid concrete), the drill bit is equipped with a discharge hole at the bottom and a special drill bit for screw pile drilling tools that can be opened and closed; the tamping and diameter expansion process is implemented from bottom to top, and if hammering assistance is required during hole drilling, a drill bit with telescopic function, no discharge hole on the side, discharge hole at the bottom and an opening and closing gate can be used.

[0034] In this embodiment, dry-hard concrete is the material used for the rammed and expanded diameter body. It is made by re-mixing and stirring superfluid concrete and dry cement mixture according to the designed mass ratio using the upper power drill 1. (When the diameter expansion process is implemented from bottom to top, and the pile body 31 has multiple expansion bodies from the pile end to the pile top, the materials used for the expansion bodies and the pile body above the expansion bodies are all the same pile material—dry-hard concrete; or when there are no more expansion bodies after ramming and expanding 1 to N expansion bodies, the pile body above can use superfluid concrete). Superfluid concrete is also the pile body material and is a special pile material for pressure grouting pile technology. The rammed and expanded diameter process is implemented from bottom to top. Implemented from top to bottom, the enlarged diameter body uses dry-hard concrete. Dry cement mixture is a mixture of cement and sand / cement and gravel / cement and gravel, plus admixtures, where cement is mixed with one or more other materials at a specific design mass ratio until homogeneous. The strength of the dry-hard concrete used for the enlarged diameter body (not less than the strength of the main pile material) and the geometric dimensions of the enlarged diameter body must meet the shear and punching shear resistance calculations. The main pile body uses super-fluid concrete / dry-hard concrete. The strength of the main pile body concrete used for compression piles should meet the design requirements for pile bearing capacity. The compressive bearing capacity of the axially compressed pile's cross-section should comply with the industry standard "Technical Specification for Building Pile Foundations" JGJ. According to the relevant provisions of 94; the main body of the pile is made of super-fluid concrete. The concrete strength of the main body of the pile for tension piles should meet the design requirements of the tensile bearing capacity of the pile. The crack control calculation of tension piles should comply with the relevant provisions of the current industry standard "Technical Specification for Building Pile Foundations" JGJ 94; the main body of the pile is made of super-fluid concrete. For piles resisting horizontal loads, the bearing capacity calculation is based on the uniform cross-section cast-in-place pile with the design diameter of the main body of the pile. When calculating the horizontal bearing capacity and displacement according to the relevant provisions of the current industry standard "Technical Specification for Building Pile Foundations" JGJ 94, the concrete strength of the main body of the pile only needs to meet the design and specification requirements.

[0035] Example 2

[0036] This embodiment provides a pile 3 prepared by a multifunctional dual-power drilling tool for pile diameter expansion, which includes: a pile body 31 and an expansion body 32. The pile body 31 is a straight rod structure; the surface of the pile body 31 is a smooth rod without threads, or a rod that is entirely threaded or partially threaded; at least one expansion body 32 is provided on the pile body 31; the expansion body 32 is divided into a non-connected expansion body and a connected expansion body; the shape of the expansion body 32 includes any one of the following: spherical, elliptical, and gourd-shaped; the gourd-shaped expansion body on the pile body 31 can be designed in an inverted arrangement or an upright arrangement. In this embodiment, preferably, the pile body 31 is a straight rod, either a smooth rod without threads, a rod with threads, or a rod with threads in some parts. The pile body 31 consists of the portion axially inserted into the enlarged diameter body 32, the pile body between the enlarged diameter bodies 32, and the pile body above and below the enlarged diameter bodies 32. The diameter and length of the pile body 31 are the conventional dimensions for soft soil treatment (for composite foundation reinforcement, the pile body diameter is 300mm to 600mm; for foundation piles, the pile body diameter is 400mm to 800mm). The pile length should be controlled with a suitable length-to-diameter ratio, considering the effective pile length for bearing capacity and the influence of pile length on settlement. Generally, the length-to-diameter ratio should not exceed 60; for piles with low undrained shear strength (less than 10kPa) along the pile side soil, the length-to-diameter ratio should not exceed 40. Note: The length-to-diameter ratio is the pile length / the diameter of the pile body). Specific parameters should meet the design and specification requirements. At least one enlarged diameter body is provided on the main body of the pile 31. The location of the enlarged diameter body is determined according to the geological characteristics, design and specification requirements, and is located at the upper part (excluding the pile top) / upper middle part / middle / lower middle part / lower part / pile end of the main body of the pile 31.

[0037] In this embodiment, preferably, the expansion body 32 is located on the upper part of the pile body 31 (excluding the pile top). The principle for setting the position of the expansion body 32 is: the end resistance of the stratum should be relatively large, the layer thickness should be large, the compressibility should be small, and the stratum structure should be relatively stable. The depth of the first expansion body 32 on the upper part of the pile body 31 should also meet the requirement of a burial depth of not less than 4m to ensure that the overlying soil pressure has sufficient constraint force on the expansion body during compaction. For compression piles, the expansion body 32 should preferably be set on the bearing layer. The expanded diameter body 32 should be fully inserted into the bearing stratum. The thickness of the bearing stratum below the vertical center (maximum cross-section) of the expanded diameter body 32 should not be less than 3.0 times the diameter of the main pile body; when there is a weak underlying layer, it should not be less than 4.0 times the diameter of the main pile body. For pull-out piles, the expanded diameter body 32 should be set in the lower part of the bearing stratum, and the expanded diameter body 32 should be fully inserted into the bearing stratum. The purpose is to ensure that the bearing stratum has a relatively large confining pressure on the expanded diameter body during the tamping and expansion of the expanded diameter body, so as to ensure that the minimum amount of material is filled and to obtain the maximum tamping and expansion density of the expanded diameter body.

[0038] In this embodiment, preferably, the enlarged diameter body, the overall structure of the enlarged diameter body between the pile tip and the pile top, is similar to a spherical / ellipsoidal body. It is arranged individually or as a unit on the main body of the pile 31. The unit-connected enlarged diameter body is similar to a gourd shape. The gourd-shaped unit-connected enlarged diameter body is composed of two or more independent enlarged diameter bodies. The gourd-shaped unit-connected enlarged diameter body is designed to be arranged inverted on the main body of the pile 31. The enlarged diameter bodies in the inverted arrangement decrease in size from top to bottom, causing the pile body to move vertically downwards and create a wedge shape on the soil around the pile. The body expansion effect fully utilizes the potential of the soil layer with good properties around the pile, which is beneficial to reducing the settlement. The gourd-shaped connected expansion body between the pile end and the pile top is designed on the main body 31 of the pile body in an inverted arrangement. This connected expansion body arrangement is suitable for friction type or end-bearing friction type vertical compression piles. If it is used for vertical compression piles and also meets the requirements of vertical pull-out (anti-buoyancy) piles, it is consistent with the design method of the connected expansion body at the pile end, and is arranged upright, with the expansion body increasing in size from top to bottom. The overall structure of the expanded diameter body at the pile tip is similar to a spherical / ellipsoidal body, and it can be arranged individually or in a connected manner. The connected expanded diameter body is similar to a gourd shape. The gourd-shaped connected expanded diameter body is composed of two or more independent expanded diameter bodies. The design method of the gourd-shaped connected expanded diameter body at the pile tip is: upright arrangement. In the upright arrangement, the expanded diameter body increases in size from top to bottom. The overall structure is similar to an extended foundation, which is equivalent to enlarging the contact area between the pile tip and the bearing layer, thus maximizing the bearing capacity of the pile tip and reducing the settlement. Regarding the calculation of the bearing capacity of the expanded diameter body, for the calculation of the bearing capacity of the expanded diameter body at the pile tip, refer to the equivalent calculation area of ​​the soil properties of the reinforced soil layer in the "Design Code for Carrier Pile" JGJ 135—2007, and calculate the area corresponding to different soil properties when different three-blow penetrations are met; for the calculation of the bearing capacity of the expanded diameter body above the pile tip, multiply the annular horizontal projected area by the end resistance of the bearing layer by the rammed reinforcement coefficient; for the uppermost expanded diameter body of the pile body, when the depth is not greater than 4 times the diameter of the expanded diameter body, the bearing capacity of the expanded diameter body is calculated using Terzaghi's formula for the ultimate bearing capacity of circular shallow foundations, and the calculation area is the annular horizontal projected area; the deformation calculation (vertical settlement, uplift and horizontal displacement) of the expanded diameter pile body (type 3) should meet the requirements of the current industry standard "Technical Specification for Building Pile Foundations" JGJ94.

[0039] In this embodiment, preferably, the size and shape of the enlarged body are determined by the compaction or hardness of the soil in the stratum where the enlarged body is located, the tamping method, the material properties of the enlarged body, the intensity of the tamping energy, the design standard for three-blow penetration at the final hammer blow, or the total amount of filler material based on the design value of three-blow penetration. For soil layers with different soil properties being tamped, the three-blow penetration standard is referenced to the standard "Design Code for Carrier Piles" JGJ 135—2007; drawing on the mature compaction standard for carrier piles: for tamping and compaction standards controlled by the amount of filler material, the maximum amount of filler material should not exceed 1.8m when the main diameter of the pile body is 300mm to 500mm (enlarged bottom or enlarged head at the pile end). 3For piles with a large main diameter, the pile spacing is also large, and the amount of filling material can be appropriately increased. Specific data should be determined by testing. The purpose of controlling the maximum amount of filling material is to avoid disturbing the quality of adjacent pile end expansion bodies when ramming and expanding the pile end expansion body, while maximizing the compaction of the bearing layer.

[0040] In this embodiment, preferably, the size and shape of the enlarged body are determined by the above comprehensive factors, taking into account the current industry standard "Technical Specification for Building Pile Foundations" JGJ94 and referencing the proportional relationship between the radial diameter and axial height of the enlarged body and the diameter of the main pile body in current enlarged pile technical standards or regulations, so as to meet the geotechnical requirements for shear and punching shear resistance of the enlarged body, thus achieving the most cost-effective result in terms of both technology and economy. Specific reference data: the ratio of the radial diameter of the enlarged body to the diameter of the main pile body should not be greater than 2.5, and the axial height of the enlarged body should be (1-1.5) times the radial diameter of the enlarged body.

[0041] In this embodiment, preferably, the number and axial spacing of the non-connected expansion bodies are determined comprehensively based on the geological characteristics, design requirements, and the principle of minimum vertical center spacing of the expansion bodies (the minimum vertical center distance when the pile bears the vertical load and the end resistance stress of adjacent expansion bodies cannot be superimposed).

[0042] Specific reference data: Research results show that the spacing between the expanded diameter bodies is most closely related to the expanded diameter amount. It is advisable to determine the spacing by adding 4 to 6 times the expanded diameter amount to the height of the expanded diameter body. A larger value should be used for smaller expanded diameter amounts, and a smaller value should be used for better soil properties. Note: The expanded diameter amount is (expanded diameter body diameter - pile body diameter) / 2. In this embodiment, the preferred design method of arranging the connected expanded diameter bodies on the pile body 31 is based on a comprehensive consideration of soil characteristics, stress diffusion effects, and pile application type. The design quantity of both non-connected and connected expanded diameter bodies on the pile body 31 should be determined based on the foundation type, soil characteristics, vertical force bearing direction, and stress influencing factors of the expanded diameter body, adhering to the principle of being cost-effective from both technical and economic perspectives. Specific reference data: For piles used for compressive strength, 1 to 4 expansion bodies are set, with 2 to 3 expansion bodies being the most commonly used technical solutions; for piles used for tensile strength, 1 to 2 expansion bodies are recommended. This is mainly due to the special nature of pile foundation tensile strength. Setting too many expansion bodies not only does not significantly increase the tensile bearing capacity, but also requires a large amount of reinforcement in the pile body, which is less economical.

[0043] In this embodiment, preferably, when non-connected or connected expanded diameter bodies are applied to vertical tension piles, the design of the embedment depth for different bearing layers is based on the influence of the internal friction angle of different soil types on the height of the fractured column surface. According to the relevant provisions of the current expanded diameter pile technical standards or regulations, the depth of the expanded diameter body affects the height of the fractured column surface. The greater the embedment depth, the smaller the ratio of the height to the diameter of the expanded diameter body. Therefore, the expanded diameter body should not be too deep or too shallow. The specific reference data for the length of the fractured surface of the upper part of the vertical center of the expanded diameter body with the diameter of the expanded diameter body as the cylinder is: (14~18) the expanded diameter amount. The larger the value is for better soil properties, and the smaller the value is for poorer soil properties. In this embodiment, preferably, when the pile body 31 is used for composite foundation reinforcement, no steel cage is provided; when used for pile foundation piles, a steel cage is provided (within the depth range of the pile body 31 with the steel cage, super-fluid concrete needs to be pressure-grown, and the steel cage is sunk using the inverted cage process).

[0044] In this embodiment, preferably, when the pile body 31 is used as a composite foundation reinforcement, the pile-soil stress ratio needs to be adjusted to reduce settlement, and a pile cap can be added. If the pile cap is located within 6.0m below the pile top and there is a stable soil layer with good soil properties, in order to add an auxiliary function to the pile cap—increasing the single pile bearing capacity, the pile cap structure design is as follows: the axial equal diameter pile body length is not greater than 4 times the pile cap diameter and not less than 0.8m, the difference between the pile cap diameter and the pile body 31 diameter is not greater than 0.30m, and the pile cap and the pile body 31 are connected by an inverted truncated cone. The angle between the extended line of the inverted truncated cone generatrix and the central axis of the pile body 31 is in the range of 30° to 45°. The pile cap can be implemented by adding a sleeve drilling tool and integrating pile driving for hole forming and grouting. If the pile cap is located in a shallow burial depth below the pile top and the soil layer is unstable, with general or poor soil properties, a conventional design and conventional implementation method is adopted: front-cut method / rear-supported formwork grouting method. In this embodiment, the main material of the pile body is superfluid concrete / dry-hard concrete. The specific choice of material depends on factors such as construction technology, soil properties around the pile, soil moisture content (saturation), pile application, and bearing capacity requirements. Superfluid concrete, a special material for underwater cast-in-place piles, is characterized by high fluidity, strong impermeability, high strength, good durability, and environmental friendliness. When used as a foundation pile, it facilitates the insertion of the reinforcing cage. Dry-hard concrete, used for the enlarged diameter body and main pile body, requires strong vibration compaction during construction and is more suitable for ramming compaction. It has higher compressive strength and elastic modulus, enabling it to withstand greater loads. It also has better durability, with high density and good impermeability, effectively preventing moisture and chemical substances from eroding and damaging the concrete, thus extending its service life.

[0045] Example 3

[0046] This embodiment provides a method for preparing type 3 piles, including the following steps: Relationship between site soil type and bearing characteristics: 1. The pile tip depth is distributed with stable soil layers and good soil properties, and the upper soil layers are unconsolidated soft clay, newly filled soil, etc., with negative skin friction; suitable bearing characteristics: end-bearing pile. 2. The pile tip depth is distributed with stable soil layers and good soil properties, and the upper soil layers are of average soil properties; the lower part of the soil around the pile is distributed with stable soil layers and good soil properties, and the upper soil layers are of average soil properties; suitable bearing characteristics: friction end-bearing pile. 3. The upper part of the soil around the pile is distributed with stable soil layers and good soil properties, and the lower soil layers are of average soil properties; suitable bearing characteristics: original friction pile, which is converted into a friction end-bearing pile after the pile body is enlarged. 4. The distribution pattern of the soil layers around the piles shows a gradual change from soft to hard or uniform soil properties from top to bottom. The original end-bearing friction piles or friction piles are transformed into friction end-bearing piles after the pile body is enlarged. The rammed and enlarged body changes the traditional bearing properties. The original friction piles and end-bearing friction piles are transformed into friction end-bearing piles. The multi-end bearing and multi-segment side friction greatly improve the bearing capacity of the single pile and significantly reduce the corresponding deformation.

[0047] For details on pile types with various bearing characteristics, please refer to the appendix. Figures 37-40The construction method involves the matching relationship between the drilling tools and the compaction of the soil strata. Based on the variation of equivalent shear wave velocity values ​​from shallow to deep, foundation soil can generally be classified as follows: Soft soil (average shear wave velocity ≤ 140 m / s) – Class IV: silty soil, loose fine and silty sand, recently deposited cohesive soil, and fill with a foundation soil allowable bearing capacity fa < 130 kPa; Medium-soft soil (140 m / s < average shear wave velocity ≤ 250 m / s) – Class III: loose gravel, coarse and medium sand. Class II site soils include: dense and medium-dense fine and silty sand, cohesive soil with allowable bearing capacity fa ≤ 250 kPa and fill soil with fa ≥ 130 kPa; medium-hard site soils (250 m / s < average shear wave velocity of soil layer ≤ 500 m / s) — Class II site soils: medium-dense and loose gravelly soil, dense and medium-dense gravel, coarse and medium sand, cohesive soil with allowable bearing capacity fa > 250 kPa; hard site soils (500 m / s < shear wave velocity of soil layer) — Class I site soils: rock, dense gravelly soil. Based on the soil hardness and the distribution of soil layers, the foundation soil can be simply divided into two zones: the displacement zone (soft and medium-soft soil, excluding soils with high water content or saturated cohesive soil) – corresponding to drilling tool types: full displacement (drilling tools primarily for displacement) and partial displacement (threaded blade displacement drilling tools: specialized tools for forming threaded piles); and the discharge zone (excluding medium-hard and hard soils): ordinary long auger drilling tools. The appropriate selection of drilling tools matches the corresponding foundation soil type, strictly adhering to the "loose displacement dense discharge" geotechnical engineering theory, effectively compacting the soil around the pile or maximizing its dense structure. The transformation of bearing characteristics and the appropriate application of drilling tools have a significant positive impact on the single pile's bearing capacity and deformation. Furthermore, by applying geotechnical expertise and relevant industry standards or similar technical specifications, the pile's related parameters are optimized and designed, making it suitable for composite foundation reinforcement and pile foundation foundations.

[0048] The specific factors to consider in the design of pile body parameters are as follows:

[0049] Based on the geological characteristics and the requirements for construction methods and pile types, and drawing on soil mechanics knowledge, the location of the expanded diameter bodies is determined (selecting a structurally stable soil layer with low compressibility and high bearing capacity as the bearing soil layer for the pile body or pile tip expanded diameter body is crucial for the pile's bearing capacity), the number and axial spacing of the expanded diameter bodies, and the requirements for compaction density are determined. Combining the design requirements for single pile bearing capacity and deformation values, project site test data and experience, and considering pile foundation knowledge and the group pile effect, various factors are comprehensively considered to scientifically and rationally calculate and design the main body strength, pile diameter, pile length, and pile spacing (while also considering that the minimum center distance between adjacent expanded diameter bodies meets the requirements of the industry standard "Code for Design of Building Pile Foundations" JGJ94, or that adjacent pile expanded diameter bodies were originally on the same horizontal line, such as...). If the bearing layer thickness meets the specifications, a staggered design can be adopted. In this case, only the center-to-center distance between the main pile bodies 31 needs to meet the standard requirements. Specific reference data: the minimum center-to-center distance between piles should not be less than (2.0~2.5) times the diameter of the expanded diameter body (the value is related to the construction method, soil properties, and water saturation). When the minimum value is reached and the vertical compressive strength of the pile group foundation is greater than 5 times the diameter of the main pile body 31, the expanded diameter bodies of adjacent piles can also be staggered. The vertical stagger should not be less than the height of one expanded diameter body. The staggered arrangement of the expanded diameter bodies can reduce the mutual influence of the end resistance of horizontally adjacent expanded diameter bodies and can significantly improve the bearing capacity of a single pile. This is because staggering the expanded diameter bodies is equivalent to increasing the pile spacing, which is conducive to the performance of the bearing capacity of a single pile. When this type of pile is used for pile foundations, for pile foundations with no less than 3 rows and no less than 9 piles, for displacement piles, the pile spacing for unsaturated soil should not be less than 4.0 times the main diameter of the pile body, and the pile spacing for saturated cohesive soil should not be less than 4.5 times the main diameter of the pile body; for partially displacement piles, the pile spacing should not be less than 3.5 times the main diameter of the pile body; for non-displacement piles, the pile spacing should not be less than 3.0 times the main diameter of the pile body; when used as vertical reinforcement in composite foundations, the pile spacing can be determined according to the bearing capacity and replacement ratio of the composite foundation, and the pile spacing should preferably be (3 to 6) times the main diameter of the pile body. When there is saturated silt and cohesive soil within the pile length range, the higher value should be used. The above pile spacing determination takes into account the minimum spacing requirements of the expanded diameter body on a horizontal line; however, this requirement does not apply to staggered designs. Considering the impact of the ramming and expansion of the borehole on adjacent piles, the optimal construction sequence is selected to minimize the impact of ramming and expansion while ensuring reasonable efficiency. Based on the above factors and conditions, a reasonable construction process is formulated, and effective drilling tools are used to achieve twice the result with half the effort while ensuring quality.

[0050] Based on the above conditions and factors, the innovative technology involves two forms of construction processes to achieve pile body expansion and grouting / ramming of the main pile body.

[0051] A multi-powered drilling tool for pile diameter expansion involves the following construction process: First, the expansion is carried out from top to bottom. The lower power drill 2, while displacing soil / partially displacing soil, drills to the designed depth of the first expansion body and stops. The upper power drill 1, while quantitatively mixing and downward rotary discharge of dry-hard concrete, re-compacts the pile. The dry-hard concrete is gradually extruded from the discharge hole, gradually expanding the diameter. Once the required density is achieved, the expansion is complete. The lower power drill 2 continues displacing soil / partially displacing soil to the designed depth of the next expansion body, repeating the expansion process until the pile end expansion is complete. Then, with the assistance of the rotary discharge function of the upper power drill 1, super-fluid concrete is simultaneously poured while the lower power drill 2 is raised until the pouring reaches the pile top elevation. The pile body with the expanded diameter is then completed. The dry-hard concrete used for the expansion is a mixture of super-fluid concrete and dry cement, re-mixed and stirred by the upper power drill 1 according to the designed mass ratio. The second method involves expanding the pile diameter from bottom to top. The lower power drill 2, using soil displacement / partial displacement / discharge, drills to the designed depth at the pile tip and stops. The upper power drill 1, while quantitatively mixing and downward rotary discharge of dry-hard concrete, simultaneously compacts the pile. The dry-hard concrete is gradually squeezed out from the discharge hole, gradually expanding the pile diameter until the required density is achieved. The expanded pile tip or N consecutive expanded pile sections are then compacted. With the assistance of the rotary discharge function of the upper power drill 1, super-fluid concrete is simultaneously poured in while the lower power drill 2 is raised until the concrete reaches the pile top elevation. The pile body with the expanded diameter is then complete. (The following procedures are suitable for soil displacement / discharge drilling methods.) After the pile tip expanded pile section or N consecutive expanded pile sections are completed, dry-hard concrete is filled while light compaction is performed while the lower power drill 2 is raised to expand the pile body. The main construction is carried out until the designed depth of the previous expansion body is reached. The expansion body is then repeatedly compacted and expanded. The above process is repeated until all the expansion bodies of the pile body are completed. Then, while filling with dry-hard concrete, the pile body is lightly compacted and expanded, and the lower power drill 2 is raised simultaneously until it is compacted to the pile top elevation. The pile body with the expansion body is then completed. Alternatively, if there are no more expansion bodies after completing 1 to N expansion bodies, the main material of the pile body above can be super-fluid concrete. With the assistance of the rotary pumping function of the upper power drill 1, the pressure grouting process is carried out until the pile top elevation is reached. The pile body with the expansion body is then completed. The dry-hard concrete is the material used for compacting and expanding the expansion body. It is made by re-mixing and stirring super-fluid concrete and dry cement mixture according to the design mass ratio by the upper power drill 1.

[0052] Note: When the soil layer at the pile body diameter expansion or pile end diameter expansion (base expansion) is rich in water or contains confined water, the sealing ramming expansion method should be adopted during the ramming expansion. During the ramming expansion, ensure that the ramming filling material has a certain height inside the core tube. When the volume of the expanded body covers the discharge hole and water cannot penetrate into the core tube, the hammer bottom can be level with the discharge hole during the ramming expansion to increase the ramming expansion effect.

[0053] The selection of construction techniques and pile materials has different advantages and disadvantages in terms of the impact on the bearing capacity of a single pile and construction efficiency. Based on the bearing capacity of the single pile, it can be divided into four types: The first type, under the same conditions, has the highest single pile bearing capacity. The construction technique involves ramming the expanded diameter body from bottom to top, with the main pile body being constructed in a cross-construction process. The method uses a soil-displacement drilling tool, which is primarily based on extrusion. The pile body material is entirely dry-hard concrete. The disadvantage is that the construction efficiency is slightly slower. The second type, under the same conditions, has a relatively high single pile bearing capacity. The construction technique involves ramming the expanded diameter body from top to bottom, followed by pressure grouting. The method uses a soil-displacement drilling tool, which is primarily based on extrusion. The pile body material, except for the expanded diameter body which uses dry-hard concrete, uses super-fluid concrete for pressure grouting. The construction efficiency is faster than the first type.

[0054] The third type, under the same conditions, with a slightly higher single pile bearing capacity, adopts the construction process of expanding the diameter body by ramming from top to bottom and then grouting. The construction method uses a threaded blade soil squeezing drill to form the hole. Except for the expansion body, which uses dry hard concrete, the main body of the pile is grouted with super-fluid concrete. The construction efficiency is faster than the second type.

[0055] The fourth type, under the same conditions, boasts high single-pile bearing capacity (compared to other diameter expansion processes, such as high-pressure cement grouting expansion, jacking device rotary cutting expansion, and repeated driving and grouting expansion). The construction process involves bottom-up ramming expansion followed by pressure grouting. The method uses a soil-discharge drilling tool for hole formation. Except for the expanded diameter body and the main pile body between the expanded diameter bodies, which use dry-hard concrete, the rest of the pile body is grouted with super-fluid concrete, resulting in the fastest construction efficiency. This innovative technology integrates the advantages of rammed and expanded piles and drilled pressure grouting piles into a new process: rammed and expanded pressure grouting variable-diameter piles. The unique advantages are highlighted through process comparison.

[0056] Disadvantages of rammed piles; methods of sinking casings or outer sleeves into the foundation soil: In soft and medium-soft soil, the method involves ramming the casing, ramming the inner and outer sleeves, vibration, static pressure, etc., to squeeze the soil to form a hole. In medium-hard soil, the method of using a soil removal method with a spiral drill is used to form a hole, and then the spiral drill is pulled out before sinking the casing or outer sleeve. Regardless of whether soil is squeezed or the casing or outer sleeve is driven in a relay, the efficiency is lower than that of the innovative technology. Filling the casing or outer sleeve requires on-site loading with a loader to unload the material into the hopper in front of the pile hole, and then filling it in batches by manual labor or with the assistance of a winch. The innovative technology directly delivers the material to the core tube of the outer sleeve through the anchor spraying equipment and mixes it with super-fluid concrete. While mixing, the ramming is carried out, which is very efficient. Especially when the concrete is poured into the hole in the carrier pile process, the hammer needs to be lifted out of the hole, and the casing is pulled out after the pouring is completed. When the innovative technology is used for pressure grouting, the mixing hammer does not need to be lifted out. It only rotates to assist the rapid pouring of concrete. The drill bit is lifted out of the drill bit hole while pouring. The main body of the pile is poured in the first stage, saving time. The filling material is manually installed at the borehole opening, and if the filling material encounters a water-rich stratum during hammering, and the bottom of the casing is not sealed in time, water can rush into the casing and mix with the material, easily creating a vacuum effect when the hammer is lifted, leading to hammer slippage. The slightly better soil above the pile tip is not utilized for diameter expansion, resulting in wasted bearing capacity. Manual filling involves on-site loader handling, which can easily disturb the already completed pile head. After the fluidized concrete is expanded into a pile, the expanded diameter will have a certain relaxation effect, reducing its expansion coefficient, which is therefore lower than that of dry-hard concrete. Disadvantages of drilled grouting piles: Drilling for various methods of drilled grouting piles encounters complex and difficult-to-drill strata, resulting in either low drilling efficiency or the need to use other drilling techniques, increasing construction costs. Different diameter expansion methods for drilled grouting piles do not significantly improve pile bearing capacity or reduce deformation, resulting in low cost-effectiveness.

[0057] Advantages of innovative technologies:

[0058] 1. The expansion of the diameter of the bored pile, the density and extent of the expanded pile body on the surrounding soil (and potentially affected soil) determine the magnitude of the increase in single pile bearing capacity. Innovative technologies involve equipment and processes that maximize the relative density of the expanded soil and the expanded diameter body. In particular, the drilling tools are equipped with bottom-opening drill bits, and the pile body material is made of a single material: dry-hard concrete. The expanded diameter body and the main body of the pile, especially the pile end expanded diameter body, are compacted to the maximum extent when the hammer impact energy is used to vertically influence the bearing layer at the pile end. Therefore, the increase in single pile bearing capacity is more significant.

[0059] Note: The standard for compaction is as follows: the weight rebounds, and the penetration depth is measured three times. Each subsequent penetration depth is less than or equal to the previous one, and the cumulative value of the three penetration depths is less than the design value. The design value is determined by applying maximum compaction pressure to the soil to achieve the maximum relative density, while avoiding excessive compaction that could cause shear failure. Alternatively, the standard for compaction can be determined by calculating the total fill volume required to achieve the design value of the three penetration depths.

[0060] 2. Traditional and other patented rammed pile technologies (rammed compaction concrete piles, prestressed pipe piles with core carriers, and similar column hammer ramming and soil displacement processes) involve layered filling and ramming, with all filling done manually. This results in low automation, low construction efficiency, increased labor costs, low safety standards, and inconsistent construction quality. The innovative technology uses conveying equipment (concrete pumps, shotcrete machines) to directly and quantitatively deliver a mixture (a mixture of superfluid concrete and dry cement) according to a specific design ratio. This mixture is then re-mixed, swirled downwards, and rammed within the core tube of the lower power drill bit by the upper power drill bit. This simultaneous and continuous operation improves efficiency while maintaining quality standards.

[0061] 3. It eliminates the frequent construction failures associated with traditional processes, which lead to wasted construction costs and negatively impact the professional image of the construction team. For example, with long spiral CFG piles, threaded piles (screw piles), and SDS piles, blockages can occur due to factors such as material shortages, weather conditions, concrete quality, and worker negligence. Severe blockages are time-consuming, labor-intensive, and costly to clear, delaying construction. Similarly, when compacting cement mixtures in prestressed pipe piles, if the soil at the pile tip has high water content and the filling material is not sealed promptly, the hammer can easily become stuck. Once the hammer is embedded in the inner wall of the precast pipe pile, the longer it remains, the stronger it becomes. The consequences are serious; if the hammer cannot be retrieved, the pile is considered substandard, requiring design changes and remedial measures, resulting in equipment damage and significantly increased construction costs. The innovative technology, through its drilling tool construction, structure, and function, avoids the possibility of hammer jamming. The overall structure of the power drilling tool is assembled with the upper power drilling tool nested inside the lower power drilling tool. When the upper power drilling tool is tamping, its bottom is basically flush with the bottom of the lower power drilling tool. If the telescopic drill bit has a discharge hole on its side, the bottom of the upper power drilling tool will not penetrate the bottom of the lower power drilling tool during tamping because the bottom is closed. Even if a bottom-opening drill bit is used, the lower power drilling tool has a large torque power that can rotate, and the upper power drilling tool inside its core tube also has a certain torque that can rotate. Even after the tamped enlarged body is compacted, it has a certain constraint force on the bottom of the upper power drilling tool. When it cannot be lifted, the torque rotation of the power mechanism on the drill bit can eliminate the hammer clamping force of the enlarged body. The fundamental reason is that although the upper and lower power drilling tools are independent entities, they are also an integrated whole, so the hammer clamping phenomenon does not exist. However, when the carrier inside the prestressed pipe pile hammers the filling material, the pipe pile is constrained by the squeezing and frictional force of the surrounding soil, and the column hammer is a free body. Once the hammer clamps, if the depth is shallow, it can be excavated to the point of clamping and the pipe pile can be cut off for rescue. If it is too deep, there is no way to rescue it. Considering all the factors mentioned above, the equipment and tools used for clamping hammers do not meet these conditions, thus proving the principle that structure determines function.

[0062] 4. The innovative combination and structure of the equipment also indirectly and effectively solves the global problem that concrete pumps cannot transport dry-hard concrete. By using a shotcrete machine to transport dry cement mixture, a quantitative amount of super-fluid concrete is pumped and mixed with a quantitative amount of dry cement mixture in the lower power core tube according to a certain design mass ratio. The upper power drill bit's structure and function further mix and stir the mixture, ensuring uniform mixing to meet the dry-hard concrete standard. The mixture is then discharged to the bottom of the lower power drill bit's core tube, where the upper power drill bit tamps and expands its diameter, forming an expanded diameter body. Light tamping then forms the main body of the pile. This solves the problem that dry-hard concrete cannot be used to fill the pile body in the long spiral drilling and pressure grouting CFG pile process.

[0063] 5. In addition to diameter expansion, the main body of the pile can use a combination of one or two states of concrete, depending on geological characteristics, design requirements, and construction technology, allowing for greater flexibility in material selection. When the pile serves as a foundation reinforcement, if geological conditions permit, the main body of the pile can be filled with dry-hard concrete in layers, which can further increase the side friction resistance of the soil around the pile and improve the bearing capacity of a single pile. When the pile serves as a foundation pile, the concrete in the pile body within the length of the reinforcing cage can be pressure-grown in a super-fluid state, which is beneficial for the implantation of the inverted reinforcing cage.

[0064] 6. The application of innovative technologies has broadened the application scope and increased the efficiency of the traditional rammed and expanded pile process, resulting in higher bearing capacity and smaller deformation of the traditional long spiral drilled pressure grouting pile (CFG pile) and its extended technologies—soil displacement SDS pile and some soil displacement screw piles (threaded piles).

[0065] 7. The application of the upper power drill bit combined with the telescopic drill bit is particularly useful when encountering complex geological formations during drilling, such as when drilling into rocks larger than the pile hole diameter. The upper power drill bit can use a large-drop hammer to impact the telescopic drill bit, concentrating the impact force on the drill tip to perform high-energy shearing and crushing of the rocks into smaller pieces. Then, the lower power drill bit can be driven by a high-torque power mechanism to drill further, squeezing and expanding the larger rocks into the soil around the pile, while the smaller rocks can be rotated onto the pile hole or left between the auger blades. After successful hole formation, the pile is then pressure-grouted. Therefore, the above combination of structures and collaborative functions greatly contributes to high drilling efficiency. The advantages of this combination of equipment expand the application scope of traditional technology upgrades. It eliminates the helplessness or costly, time-consuming, and labor-intensive methods of drilling into complex geological formations using down-the-hole hammer technology followed by duct grouting or relay drilling with a long auger rig followed by pressure grouting.

[0066] The overall structure and detailed design determine its diverse functions, summarized as follows: The combination of the central mixing hammer and the anchor spraying equipment, based on the advantages of the original pressure grouting process, indirectly solves the industry problem that pumps cannot transport dry-hard concrete, making it possible to significantly improve the single pile bearing capacity of the drilled pressure grouting pile process; The collaboration between the central mixing hammer and the outer sleeve drill bit enables the mixing mixture to generate dry-hard concrete and simultaneously rotate it to the bottom of the outer sleeve drill bit, while simultaneously tamping and expanding the dry-hard concrete, which is then squeezed out through the drill bit discharge hole to form an expanded diameter body; This solves the problem of the discontinuity of manual batch filling and tamping in the traditional tamping and expanding pile process, changes the filling and expanding method, and saves time; The outer sleeve drill bit is compatible with different construction methods and adapts to various types of site soils, implementing the geotechnical engineering concept of "loose compression and dense discharge," and is compatible with different construction methods: full compression, partial compression, and soil discharge drill bits, and can hammer and extend the drill bit during drilling to efficiently form holes. The above-mentioned drilling tools and hammer-assisted functions solve the problems encountered when sinking the casing of rammed and expanded piles into medium-hard soil, where it is difficult to follow the casing. The solution involves excavating soil to form the hole and then sinking it, using a relay method to complete the hole formation. It also solves the problem of using down-the-hole hammer technology to form the hole and then using a relay method to grout concrete when drilling long spiral drilled and grouted piles in soil layers containing large-diameter gravel, where drilling is impossible. The traditional methods of hole formation and pile formation are cumbersome, cannot achieve integrated construction, and the additional procedures increase construction costs and waste time. When encountering complex strata during drilling, where drilling is slow or difficult, the central mixing hammer assists in drilling by impacting the telescopic drill bit, improving efficiency. Because of this assistance mode, the driving power of the outer casing drill bit is reduced, and the drive mechanism can be appropriately reduced in configuration, lowering the cost of the drilling rig. Different structural designs of the telescopic drill bit are also available. By combining different tamping and expansion methods, the direction of hammer impact energy radiation is controlled according to the relative density or compression modulus of the bearing stratum when tamping and expanding the pile body to achieve different effects: When the relative density or compression modulus of the bearing stratum is high, the pile end is tamped and expanded (base expansion), with the tamping focus on the radial horizontal direction, aiming to maximize the effective cross-sectional area of ​​the expanded body; when the relative density or compression modulus of the bearing stratum is not too high, the pile end is tamped and expanded (base expansion), with the tamping focus on the axial vertical downward direction, aiming to achieve the maximum compaction effect and improve the end bearing capacity of the bearing stratum; when tamping and expanding the expanded body above the pile end, the tamping focus is on the radial horizontal direction, which maximizes the effective cross-sectional area of ​​the expanded body while also improving the relative density or compression modulus of the bearing stratum to varying degrees.

[0067] The above innovative technologies combine the unique advantages of machinery with the expansive theory that criticizes current problems, resulting in simplification, leveraging strengths and avoiding weaknesses, perfect synergy, and outstanding performance.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-functional dual-power drilling tool for pile diameter expansion, characterized in that, include: The upper power drill bit includes: an upper power mechanism and a central stirring hammer; The upper power mechanism is equipped with an upper power reducing joint, which has a driving regular polygonal hole. The central stirring hammer is divided into upper and lower parts according to its structure. The upper part is a solid long cylinder with a regular polygonal cross-section, and the lower part is a solid cylinder with a threaded blade structure. The long cylinder passes axially through the driving regular polygonal hole of the upper power reducing joint, and the top of the long cylinder is connected to the winch. The central stirring hammer can rotate in conjunction with the upper power mechanism, and can also perform axial lifting and lowering movements under the drive of the winch. The lower power drill string includes: a lower power mechanism and a lower casing drill string; The lower power mechanism is equipped with a lower power reducing joint. The lower sleeve drill bit consists of a hollow drill rod and a telescopic drill bit. The top of the drill rod of the lower sleeve drill bit is fixedly connected to the lower power reducing joint, and the bottom of the drill rod of the lower sleeve drill bit is connected to the telescopic drill bit. The lower power mechanism has two feed ports: one for conveying superfluid concrete and the other for conveying dry cement mixture. The central mixing hammer is fitted into the hollow drill rod of the lower sleeve drill bit. The upper power mechanism and the lower power mechanism are rigidly connected by a connecting rod. The lower sleeve drill bit can rotate in conjunction with the lower power mechanism.

2. The multi-functional dual-power drilling tool for pile diameter expansion according to claim 1, characterized in that, The upper power mechanism has two upper connection points symmetrically arranged on both sides of its upper end; The upper connection point of the upper power mechanism is connected to the wire rope of the first winch; The top of the central stirring hammer is provided with an upper connection point; The upper connection point of the central stirring hammer is connected to the wire rope of the second winch via a lifting device.

3. The multi-functional dual-power drilling tool for pile diameter expansion according to claim 1, characterized in that, The upper power mechanism has two lower connection points symmetrically arranged on both sides of its lower end; The lower power mechanism has two upper connection points symmetrically arranged on both sides of its upper end; The lower connection point of the upper power mechanism is rigidly connected to the upper connection point of the lower power mechanism; at the same time, both the upper and lower power mechanisms are slidably mounted on the slide of the drilling rig tower via slips.

4. The multi-functional dual-power drilling tool for pile diameter expansion according to claim 1, characterized in that, One inlet of the lower power mechanism is connected to a concrete pump for conveying superfluid concrete; the other inlet of the lower power mechanism is connected to a shotcrete equipment for conveying dry cement mixture.

5. The multi-functional dual-power drilling tool for pile diameter expansion according to claim 1, characterized in that, The telescopic drill bit includes: a drill bit outer sleeve and an inner drill core; The inner core is installed inside the drill bit outer sleeve; The inner core can extend from the bottom end of the drill bit outer sleeve; The inner core is provided with a discharge hole on its periphery.

6. The multi-functional dual-power drilling tool for pile diameter expansion according to claim 1, characterized in that, The drill rod of the lower sleeve drill bit has a structure that has full squeezing / partial squeezing / soil removal functions.

7. The method for preparing shaped piles using the multifunctional dual-power drilling tool for pile diameter enlargement according to claim 1, characterized in that, The ramming and expansion of the diameter body is carried out from top to bottom, including: The lower power drill bit, while displacing / partially displacing soil, stops drilling at the designed depth of the first expansion body. The upper power drill bit, while quantitatively mixing and downward rotary discharging dry-hard concrete, re-compacts and expands the pile. The dry-hard concrete is gradually squeezed out from the discharge hole, gradually expanding the diameter. Once the required density is achieved, the compaction is completed. The lower power drill bit continues to displacing / partially displacing soil to the next designed depth of the expansion body, repeating the compaction and expansion process until the pile end is compacted and expanded. Then, with the assistance of the rotary discharging function of the upper power drill bit, the lower power drill bit is lifted while simultaneously grouting super-fluid concrete until it reaches the pile top elevation. The pile body with the expanded diameter is then completed. The dry-hard concrete used for compacting and expanding the diameter is a mixture of super-fluid concrete and dry cement, re-mixed and stirred by the upper power drill bit according to the designed mass ratio.

8. The method for preparing shaped piles using the multi-functional dual-power drilling tool for pile diameter enlargement according to claim 1, characterized in that, The ramming and expansion of the diameter body is carried out from bottom to top, including: The lower power drill bit, while displacing / partially displacing / removing soil, stops drilling at the designed depth of the pile tip. The upper power drill bit, while quantitatively mixing and downward rotary discharging dry-hard concrete, simultaneously compacts and expands the pile. The dry-hard concrete is gradually squeezed out from the discharge hole, gradually expanding the pile diameter until the required density is achieved. The expanded pile tip body or N consecutive expanded pile tips are then compacted and formed. With the assistance of the upper power drill bit's rotary discharging function, super-fluid concrete is simultaneously poured in while the lower power drill bit is raised until it reaches the pile top elevation, completing the variable-diameter pile body with the expanded pile tip. After the expanded pile tip body or N consecutive expanded pile tips are constructed, dry-hard concrete is filled while lightly compacting and expanding the pile tip while the lower power drill bit is raised to construct the main pile body until the designed depth of the previous expanded pile is reached. Repeat the tamping and expansion of the pile body until all the pile body expansion is completed. Then, while filling with dry-hard concrete, lightly tampe and expand the pile body, and simultaneously lift the lower power drill bit until the pile top elevation is reached, and the pile body with the expanded diameter is completed. Alternatively, after completing 1 to N expansion bodies and there are no more expansion bodies above, the main material of the pile body above is the super-fluid concrete. With the assistance of the rotary drilling function of the upper power drill bit, the pressure grouting process is carried out until the pile top elevation is reached, and the pile body with the expanded diameter is completed. The dry-hard concrete is the material used for tamping and expanding the pile body. It is made by re-mixing and stirring the super-fluid concrete and dry cement mixture according to the design mass ratio by the upper power drill bit.

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