Pile foundation construction equipment and construction methods with segmented adjustable pile hole diameter

Abstract

This invention provides a pile foundation construction device and method with segmented adjustable pile hole diameter. The pile foundation construction device includes a drill bit with radially retractable toothed cutters, an adjusting ring sleeved on the central rod of the drill bit, and a ground control system fixed to the drill rod. The ground control system is connected to the adjusting ring via an axial transmission component. By driving the adjusting ring to axially displace relative to the drill rod, the toothed cutters are extended or retracted. A composite hole formation of a grooved section of the pile hole wall and an enlarged bottom section can be completed in a single operation within the same pile hole. The device of this application has a simple structure and is easy to operate. It allows for segmented and precise control of the pile hole diameter. The resulting composite pile type of toothed pile and enlarged bottom pile significantly improves the bearing capacity of a single pile, reduces pile diameter and length, lowers material consumption and project investment, shortens the construction period, and demonstrates outstanding overall economic benefits.

Description

Technical Field

[0001] This application relates to the field of engineering construction technology, specifically to pile foundation construction equipment and construction methods. Background Technology

[0002] Pile foundations are a widely used form of deep foundation in civil engineering, municipal engineering, bridge engineering, and port terminals, used to transfer the load of the superstructure to deep, stable soil or rock layers. Currently, pile foundation construction mainly uses conventional pile types such as cast-in-place piles, precast pipe piles, and bored piles, increasing pile diameter and length to meet bearing capacity requirements. However, in adverse geological conditions such as soft soil, silty soil, and deep overburden, conventional uniform-section piles often need to be very large and deep, resulting in long construction periods, large material consumption, and high project investment. To address this, the engineering community has conducted extensive research on irregularly shaped piles, proposing pile types such as root piles, spiked piles, threaded steel pipe piles, enlarged-base cast-in-place piles, and expanded-base piles. By changing the geometry of the pile body or pile tip, the pile-soil contact area is increased or mechanical interlocking is formed, thereby improving the bearing capacity of a single pile.

[0003] However, existing irregular pile technology still faces many technical bottlenecks in practical application, mainly in the following aspects: First, the construction equipment is complex and the process is difficult: some irregular piles require specialized hole enlargement, extrusion, or thread forming equipment, which is expensive, cumbersome to operate, and requires a high level of technical expertise from construction personnel, thus limiting its widespread adoption; Second, the shape of the enlarged section is difficult to control precisely: existing hole enlargement processes mostly rely on hydraulic extrusion or mechanical opening mechanisms, making it difficult to achieve precise adjustment of the enlargement amount, enlargement position, and longitudinal profile according to design requirements, resulting in inconsistent hole quality; Third, the applicable geological range is limited: root piles and spiked piles... The application of irregularly shaped piles in pile foundation engineering is significantly constrained by several factors. First, drilling in hard or gravelly strata is difficult, and ensuring pile integrity in soft strata is challenging. Second, the functionality of a single pile type is limited: conventional irregularly shaped piles typically only allow for single-form diameter enlargement within the pile body or at the pile tip, making it difficult to simultaneously achieve both partial diameter enlargement and end cap enlargement within the same borehole. This hinders the full utilization of the synergistic bearing capacity of side friction and end resistance. Third, the overall economic benefits are not significant: while irregularly shaped piles can improve the bearing capacity of a single pile, their higher cost and lower construction efficiency result in less significant overall economic benefits compared to conventional pile types, making them less widely accepted in the engineering field. These issues restrict the further promotion and application of irregularly shaped pile technology in pile foundation engineering. Summary of the Invention

[0004] To address the problems of complex construction equipment, high technological difficulty, difficulty in precisely controlling the shape of the enlarged diameter section, limited applicable geological range, limited function of a single pile type, and lack of outstanding overall economic benefits in the background technology of irregular piles, this application provides pile foundation construction equipment and construction method that can change the diameter of the pile hole in sections. The construction equipment has a simple structure, the construction method is easy to operate, and the diameter of the pile hole can be precisely controlled in sections.

[0005] The first aspect of this application provides a pile foundation construction device with segmented adjustment of the pile hole diameter, including a drill bit with radially retractable toothed cutters, an adjusting ring sleeved on the central rod of the drill bit, and a ground control system fixed to the drill rod; the adjusting ring cooperates with the rear side of the radially retractable toothed cutters to limit the radial extension amount of the radially retractable toothed cutters; the ground control system is connected to the adjusting ring through an axial transmission component, and the adjusting ring can undergo axial displacement relative to the drill rod under the drive of the axial transmission component, thereby controlling the radially retractable toothed cutters to extend or retract outside or inside the large circle of the drill bit, realizing segmented adjustment of the pile hole diameter.

[0006] Furthermore, the drill bit is a three-wing scraper fishtail drill bit, with at least two sets of radially retractable toothed cutters installed inside the large circle of the drill bit. The cutting edge of the radially retractable toothed cutter is crescent-shaped, and the arc surface faces the direction of rotation of the drill bit.

[0007] Furthermore, the radially retractable toothed cutter is configured in three groups, evenly distributed along the circumference of the drill bit's large ring. Each group of radially retractable toothed cutters corresponds to a radial opening on the drill bit's large ring and extends or retracts radially synchronously under the push of the adjusting ring. An annular toothed cutter rear tray is also provided at the adjusting ring, which supports and tangentially limits the radially retractable toothed cutter.

[0008] Furthermore, the adjusting ring is a conical adjusting ring, with the central part of the ring being the thickest. It gradually transitions downwards from the thickest part in the middle to the thinnest part at the bottom, forming a lower conical section, and gradually transitions upwards from the thickest part in the middle to the thinnest part at the top, forming an upper conical section. The lower conical section contacts the rear side of the radially retractable toothed cutter through its conical surface, and is used to control the radial extension of the radially retractable toothed cutter. The upper conical section is used to prevent mud and sand in the hole from accumulating above the conical adjusting ring and blocking the annular gap between the conical adjusting ring and the drill bit center rod.

[0009] Furthermore, the axial length from the thickest part in the middle to the thinnest part at the bottom of the conical adjusting ring is 30cm, the maximum ring thickness is 20cm, and the thickness of the ring at the thinnest parts at the bottom and top is no more than 0.5mm; based on a pile diameter of 100cm, the maximum single-sided extension of the radially telescopic toothed cutter is 20cm, which increases the maximum diameter of the pile hole by 40cm compared to the normal drilling diameter.

[0010] Furthermore, the ground control system includes a fixed chuck fixed to the drill rod by a buckle and a reel set on the fixed chuck; the axial transmission component is a steel wire rope, the upper end of which is fixed to the reel by a rope clamp, and the lower end of which is connected to an adjusting ring, so that the drive of the reel is transmitted as the axial displacement of the adjusting ring.

[0011] Furthermore, the outer side of the wire rope is covered with a flexible sheath.

[0012] A second aspect of this application provides a construction method for forming grooves in the pile hole wall using the aforementioned pile foundation construction equipment, comprising the following steps:

[0013] S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter;

[0014] S2. The ground control system drives the adjusting ring to move downward relative to the drill rod, controlling the downward speed of the adjusting ring relative to the drill rod to match the drilling speed of the drill rod relative to the ground. The radially telescopic cutting tooth extends radially accordingly. When the adjusting ring descends to the predetermined position, the radially telescopic cutting tooth reaches its maximum extension, and the ground control system stops driving the adjusting ring. The drill rod continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation on the hole wall of the pile tooth section.

[0015] S3. After reaching the designed bottom depth of the pile teeth, the adjustment ring is reversed through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. The radially telescopic tooth cutter retracts to the large circle of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling.

[0016] S4. Repeat steps S1 to S3 according to the design requirements to form multiple grooves in the pile hole wall at different hole depths. The hole depth spacing between adjacent groove sections shall not be less than 1m.

[0017] A third aspect of this application provides a construction method for enlarging the pile bottom hole using the aforementioned pile foundation construction equipment, comprising the following steps:

[0018] S1. Drill to the designed enlargement starting depth using the normal pile diameter;

[0019] S2. Drive the adjusting ring to move downward relative to the drill pipe through the ground control system, and control the downward speed of the adjusting ring relative to the drill pipe to match the drilling speed of the drill pipe relative to the ground. The radially telescopic toothed cutter gradually extends radially until the adjusting ring descends to the predetermined position and the radially telescopic toothed cutter reaches the maximum extension amount, and then stop the ground control system from driving the adjusting ring.

[0020] S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter;

[0021] S4. After reaching the pile tip depth, the adjustment ring is reverse-driven through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. During the drilling process, the radially telescopic toothed cutter retracts to within the large circle of the drill bit under the resistance of the formation on the borehole wall, thus completing the hole formation of the enlarged bottom pile section.

[0022] A fourth aspect of this application provides a composite hole-forming method that simultaneously completes the grooved section of the pile hole wall and the enlarged pile bottom section within the same pile hole using the aforementioned pile foundation construction equipment. In one hole-forming process, one or more pile hole wall grooves are formed sequentially according to the method described below:

[0023] S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter;

[0024] S2. The ground control system drives the adjusting ring to move downward relative to the drill rod, controlling the downward speed of the adjusting ring relative to the drill rod to match the drilling speed of the drill rod relative to the ground. The radially telescopic cutting tooth gradually extends radially accordingly. When the adjusting ring descends to the predetermined position, the radially telescopic cutting tooth reaches its maximum extension, and the ground control system stops driving the adjusting ring. The drill rod continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation on the hole wall of the pile tooth section.

[0025] S3. After reaching the designed bottom depth of the pile teeth, the adjustment ring is reversed through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. The radially telescopic tooth cutter retracts to the large circle of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling.

[0026] S4. Repeat steps S1 to S3 according to the design requirements to form multiple pile hole wall grooves at different hole depths in sequence. The hole depth spacing between adjacent groove sections shall not be less than 1m.

[0027] Continue drilling to the initial depth of the enlarged section at the normal pile diameter, and then complete the hole formation of the enlarged section at the pile bottom according to the following method:

[0028] S1. Drill to the designed enlargement starting depth using the normal pile diameter;

[0029] S2. Drive the adjusting ring to move downward relative to the drill pipe through the ground control system, and control the downward speed of the adjusting ring relative to the drill pipe to match the drilling speed of the drill pipe relative to the ground. The radially telescopic toothed cutter gradually extends radially until the adjusting ring descends to the predetermined position and the radially telescopic toothed cutter reaches the maximum extension amount, and then stop the ground control system from driving the adjusting ring.

[0030] S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter;

[0031] S4. After reaching the pile tip depth, the adjustment ring is reverse-driven through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. During the drilling process, the radially telescopic toothed cutter retracts to within the large circle of the drill bit under the resistance of the formation on the borehole wall, thus completing the hole formation of the enlarged bottom pile section.

[0032] All diameter expansion operations are completed by driving the axial movement of the adjustment ring through the ground control system, without the need to remove the drill bit midway, ultimately forming a composite pile hole shape that combines the toothed pile segment with the enlarged bottom pile segment.

[0033] Compared with the prior art, this application has the following advantages:

[0034] (1) The equipment has a simple structure and low modification cost: The construction equipment of this application is modified based on the existing conventional drill bit for bored piles. Only a radially telescopic toothed cutter and an adjusting ring are added inside the large circle of the drill bit, and a ground control system connected by an axial transmission component is added on the ground. There is no need to equip it with a special set of hole enlargement, extrusion expansion or thread forming equipment. The equipment has a compact structure, few parts, and low modification and manufacturing costs. It is conducive to the promotion and application of existing construction equipment and overcomes the shortcomings of existing special pile construction equipment that is complex and expensive.

[0035] (2) Easy to operate and low process difficulty: The axial displacement of the regulating ring is directly driven by the ground control system. Operators can start, stop and reverse control of the expansion action on the ground without having to switch complex mechanical actions underground. The expansion and retraction actions are smooth and controllable, and the technical level requirements of the operators are low, which significantly reduces the construction difficulty of irregular piles and facilitates the standardization and promotion of the process.

[0036] (3) The diameter of the pile hole can be precisely controlled in segments: By driving the adjustment ring relative to the drill rod through the ground control system, the radially telescopic toothed cutter can be extended or retracted as needed, thereby realizing the pile diameter change at any position and any length along the depth direction in the same pile hole; by controlling the matching relationship between the downward speed of the adjustment ring relative to the drill rod and the drilling speed of the drill rod, the longitudinal profile shape of the enlarged section can also be precisely controlled, overcoming the shortcomings of the existing hole enlargement process where the enlargement amount, enlargement position and longitudinal profile are difficult to adjust precisely, and improving the consistency of hole quality;

[0037] (4) Achieving composite pile type and high functional integration in one drilling operation: The equipment and method described in this application can sequentially complete the drilling of one or more pile hole wall grooves and pile end enlargement sections in the same drilling process, without the need to remove the drill bit and change equipment midway, ultimately forming a composite pile hole shape that combines toothed piles and enlarged piles. This composite pile type can simultaneously utilize the mechanical interlocking effect formed by the local diameter expansion of the pile body and the end resistance formed by the pile end enlargement, giving full play to the synergistic bearing effect of side friction resistance and end resistance, and overcoming the shortcomings of the existing single pile type of irregular piles with limited functions;

[0038] (5) Significantly improved single pile bearing capacity and reduced pile diameter and length: After the pile is cast, the arc-shaped groove on the pile hole wall and the enlarged section at the bottom of the pile form multiple protruding "tooth"-like structures and an enlarged head at the pile end, which greatly increases the pile-soil contact area and forms a mechanical interlocking effect, effectively improving the side friction and end resistance of the single pile; Under the same design bearing capacity conditions, the pile diameter can be reduced and the pile length can be shortened, thereby reducing the amount of concrete and steel used.

[0039] (6) Shortened construction period and outstanding comprehensive economic benefits: Since the pile diameter and pile length can be reduced, the expansion and retraction actions are completed continuously under ground control, and there is no need to remove the drill and change equipment in the middle, which significantly improves the construction efficiency and shortens the drilling time of a single pile; combined with the reduction of material usage, the project investment and construction energy consumption are reduced accordingly, and the comprehensive economic benefits are significantly improved compared with conventional irregular piles, which is conducive to its promotion and application in pile foundation engineering.

[0040] (7) Wide range of applicable strata: The expansion action of the equipment is completed by the cutting of the tooth cutter, rather than relying on the hydraulic extrusion or mechanical opening mechanism to force the strata to squeeze. It has good adaptability to adverse geological conditions such as soft soil, silty soil, and thick overburden, as well as general soil layers. The tooth cutter retraction is automatically completed by relying on the stratum resistance. The process is stable and reliable, overcoming the shortcomings of the limited applicable strata range of some irregular piles.

[0041] In summary, the pile foundation construction equipment of this application includes a drill bit with radially retractable toothed cutters, an adjusting ring sleeved on the central rod of the drill bit, and a ground control system fixed to the drill rod. The ground control system is connected to the adjusting ring through an axial transmission component. By driving the adjusting ring to axially displace relative to the drill rod, the toothed cutters are extended or retracted. This allows for the completion of a composite hole formation—combining the grooved section of the pile hole wall and the enlarged bottom section—in a single pass within the same pile hole. The equipment of this application has a simple structure and is easy to operate. It allows for segmented and precise control of the pile hole diameter. The resulting composite pile type of toothed pile and enlarged bottom pile significantly improves the bearing capacity of a single pile, reduces the pile diameter and length, lowers material consumption and project investment, shortens the construction period, and demonstrates outstanding overall economic benefits. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the overall structure of the pile foundation construction equipment.

[0044] Figure 2 This is a schematic diagram of a radially telescopic toothed cutter and an adjusting ring.

[0045] Figure 3 This is a schematic diagram of the ground control system.

[0046] Figure 4 This is a schematic diagram of the shape of the toothed post hole.

[0047] Figure 5 Schematic diagram of the pile hole morphology for toothed pile section and enlarged base pile section

[0048] Explanation of reference numerals in the attached diagram: 1-Drill bit; 1.1-Drill bit large ring; 1.2-Radially retractable toothed cutter; 1.3-Toothed cutter rear tray; 1.4-Drill bit center rod; 2-Adjusting ring; 3-Axial transmission component; 4-Drill rod; 5-Ground control system; 5.1-Fixed chuck; 5.2-Spindle; 6-Pile hole; 7-Pile hole wall groove; 8-Pile hole wall stratum. Detailed Implementation

[0049] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0050] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0051] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0053] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0054] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0055] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0056] Firstly, this application provides a pile foundation construction device that can change the diameter of the pile hole in sections, such as... Figure 1 and Figure 2 As shown, drill bit 1 has a radially retractable toothed cutter 1.2; adjusting ring 2 is sleeved on the drill bit center rod 1.4, and ground control system 5 is fixed to drill rod 4. Adjusting ring 2 engages with the rear side of the radially retractable toothed cutter 1.2 to limit its radial extension. Ground control system 5 is connected to adjusting ring 2 via axial transmission component 3. Adjusting ring 2 can undergo axial displacement relative to drill rod 4 under the drive of axial transmission component 3, thereby controlling the radially retractable toothed cutter 1.2 to extend or retract outside or inside the drill bit's large circle 1.1, achieving segmented adjustment of the pile hole diameter.

[0057] In one embodiment, the drill bit 1 is a three-wing scraper fishtail drill bit, and at least two sets of radially retractable toothed cutters 1.2 are installed inside the large circle 1.1 of the drill bit. The cutting edge of the radially retractable toothed cutter 1.2 is crescent-shaped, and the arc surface faces the rotation direction of the drill bit.

[0058] In one embodiment, such as Figure 2 As shown, the radially retractable toothed cutters 1.2 are configured in three groups, evenly distributed along the circumference of the drill bit's large ring 1.1, meaning the circumferential spacing of the radially retractable toothed cutters 1.2 is 120°. Each group of radially retractable toothed cutters 1.2 corresponds to a radial opening on the drill bit's large ring 1.1, and synchronously extends or retracts radially under the push of the adjusting ring 2; an annular toothed cutter rear tray 1.3 is also provided at the adjusting ring 2, which supports and tangentially limits the radially retractable toothed cutters 1.2.

[0059] In one embodiment, drill bit 1 is a four-wing scraper drill bit. Four radial openings are evenly distributed along the circumference of the large circumference 1.1 of the drill bit, corresponding to four sets of radially retractable toothed cutters 1.2. These four sets of radially retractable toothed cutters 1.2 extend or retract radially synchronously under the push of the adjusting ring 2. Compared to a three-wing drill bit, the four-wing arrangement reduces the circumferential spacing of each set of radially retractable toothed cutters 1.2 from 120° to 90°. During the cutting process of one revolution of drill bit 1, the cutting coverage of the formation 8 on the borehole wall by the four sets of toothed cutters 1.2 is more uniform, which helps to improve the forming accuracy and roundness of the borehole wall groove 7 in the enlarged diameter section, making it suitable for engineering applications with high requirements for borehole wall forming quality.

[0060] In one embodiment, drill bit 1 is a PDC (polycrystalline diamond composite) drill bit. The drill body of the PDC drill bit has radial openings arranged parallel to conventional PDC cutting teeth. Radially retractable cutting teeth 1.2 are installed in the aforementioned radial openings. Its structure and the way it cooperates with the adjusting ring 2 are the same as those in the implementation of the three-wing scraper fishtail drill bit. PDC drill bits have high cutting efficiency and long service life, and are suitable for pile foundation construction in medium-hard or harder strata (such as strongly weathered rock, gravel layers, etc.). In the aforementioned strata, the borehole wall stratum 8 exerts a strong radial constraint force on the radially retractable cutting teeth 1.2. After the cutting teeth 1.2 are released from their limit by being lifted up by the conical adjusting ring 2, they can reliably retract under the stratum resistance, which has good compatibility with the retraction mechanism of this application.

[0061] It should be noted that this application does not limit the specific type of drill bit 1. Any drill bit type that has a closed drill bit ring 1.1 structure, can open a radial opening on the drill bit ring 1.1 to accommodate radially retractable toothed cutters 1.2, and can fit an adjusting ring 2 on the drill bit center rod 1.4 can be used as the basis for implementing the modification scheme of this application. The number of sets of radially retractable toothed cutters 1.2 in various types of drill bits can be determined according to the number of drill bit wings or the arrangement of the cutter wings. Preferably, it is the same as the number of drill bit wings and is evenly distributed along the circumferential direction to ensure that the cutting force of each set of toothed cutters 1.2 is balanced and does not generate eccentric load when the drill bit 1 rotates.

[0062] Specifically, the cutter rear tray 1.3 is annular and fixedly installed on the outer periphery of the adjusting ring 2, located radially inner to the radially retractable cutter 1.2, i.e., on the back side of the radially retractable cutter 1.2, and moves axially along the drill bit center rod 1.4 synchronously with the adjusting ring 2. The supporting surface of the cutter rear tray 1.3 is in contact with the rear end face of the radially retractable cutter 1.2. When the adjusting ring 2 moves downward to push the radially retractable cutter 1.2 radially outward to the set position, the cutter rear tray 1.3 continuously applies radial support to the rear end face of the radially retractable cutter 1.2, preventing the radially retractable cutter 1.2 from radially retracting or bending due to the large cutting reaction force during the cutting of the formation, thereby achieving the supporting effect of the radially retractable cutter 1.2 and ensuring that the radially retractable cutter 1.2 works stably at the set extension position.

[0063] Specifically, in one embodiment, the back tray 1.3 of the cutter is provided with tangential limiting structures on both sides, which interlock with the corresponding mating structures on both sides of the radially retractable cutter 1.2 to form a tangential constraint. When the drill bit 1 rotates for cutting, the formation of the borehole wall applies tangential resistance to the radially retractable cutter 1.2. The back tray 1.3 of the cutter, through the aforementioned tangential limiting structures, prevents the radially retractable cutter 1.2 from tangential deflection or circumferential slippage, ensuring that the radially retractable cutter 1.2 always maintains the correct circumferential position during the cutting process, thus achieving the tangential limiting effect on the radially retractable cutter 1.2. When the adjusting ring 2 is lifted and reset, the radially retractable cutter 1.2 retracts back into the drill bit's large circle 1.1 under the action of the surrounding formation resistance. The back tray 1.3 of the cutter moves upward synchronously with the adjusting ring 2, completing one cycle of expansion and contraction.

[0064] In one embodiment, such as Figure 2 As shown, the adjusting ring 2 is a conical adjusting ring, with the thickest part in the middle. It gradually transitions downwards from the thickest part in the middle to the thinnest part at the bottom, forming a lower conical section, and then gradually transitions upwards from the thickest part in the middle to the thinnest part at the top, forming an upper conical section. The lower conical section contacts the rear side of the radially retractable toothed cutter 1.2 through its conical surface, controlling the radial extension of the cutter 1.2. The upper conical section prevents sediment from accumulating above the conical adjusting ring and blocking the annular gap between the conical adjusting ring and the drill bit center rod 1.4.

[0065] In actual operation, the radially retractable toothed cutter 1.2 extends out of the drill bit's large circle 1.1 after being limited by the rear conical adjusting ring. When the conical adjusting ring is raised, the radially retractable toothed cutter 1.2 retracts back into the drill bit's large circle 1.1 under the action of the surrounding formation resistance. The design of the radially retractable toothed cutter 1.2, with its crescent-shaped cutting edge and arc surface facing the direction of drill bit rotation, can convert more tangential resistance into normal resistance, which is beneficial for the timely retraction of the radially retractable toothed cutter 1.2.

[0066] In one embodiment, to improve the retraction reliability of the radially retractable toothed cutter 1.2 in soft plastic or fluid-plastic soft soil strata, an elastic reset element is provided between the radially retractable toothed cutter 1.2 and the toothed cutter rear tray 1.3. The elastic reset element can be a rubber block or a leaf spring. The elastic reset element is arranged radially between the rear end face of the radially retractable toothed cutter 1.2 and the supporting surface of the toothed cutter rear tray 1.3. When the adjusting ring 2 pushes the radially retractable toothed cutter 1.2 radially outward, the elastic reset element is compressed accordingly, accumulating elastic potential energy. When the ground control system 5 drives the adjusting ring 2 upward in the opposite direction and the conical adjusting ring releases the radial limit on the radially retractable toothed cutter 1.2, the elastic reset element releases the elastic potential energy, applying a centripetal elastic restoring force to the radially retractable toothed cutter 1.2, assisting the radially retractable toothed cutter 1.2 to retract into the drill bit large circle 1.1. In situations where the borehole wall bearing capacity is low, such as in soft plastic or fluid plastic soft soil, and the formation resistance is insufficient to allow the radially retractable toothed cutter 1.2 to fully retract, the additional centripetal elastic restoring force provided by the elastic reset element can compensate for the insufficient formation resistance, ensuring that the radially retractable toothed cutter 1.2 can reliably retract to within the drill bit's large circle 1.1 before drilling, thus avoiding hole scraping during drilling and expanding the applicable formation range of the pile foundation construction equipment of this application.

[0067] In one embodiment, such as Figure 2 As shown, preferably, the axial length from the thickest part in the middle to the thinnest part at the bottom of the conical adjusting ring is 30cm, the maximum ring thickness is 20cm, and the thickness of the ring at the thinnest parts at the bottom and top is no more than 0.5mm; based on a pile diameter of 100cm, the maximum single-sided extension of the radially telescopic toothed cutter 1.2 is 20cm, which increases the maximum diameter of the pile hole by 40cm compared to the normal drilling diameter.

[0068] In actual operation, during the construction of bored piles, the suspended mud and sand particles carried by the drilling mud in the hole are disturbed by the rotation of the drill bit 1 and flow with the mud circulation. When the drill rod 4 stops rotating or the drilling speed decreases, the mud and sand particles settle due to gravity and tend to accumulate on the horizontal or gentle slope surface above the conical adjusting ring 2, forming a sand bridge that blocks the annular gap between the conical adjusting ring 2 and the drill bit center rod 1.4, thus hindering the axial movement of the adjusting ring 2. The reverse conical surface of the upper conical section designs the force-bearing surface above the adjusting ring 2 as an upwardly narrowing slope. Utilizing the principle that the slope angle is greater than the underwater angle of repose of the mud and sand, the mud and sand particles that settle to the upper conical section slope slide outward along the slope due to their own gravity and cannot stably accumulate above the adjusting ring 2, thereby keeping the annular gap unobstructed.

[0069] In determining the geometric parameters, the optimal parameter (maximum annular thickness t) is selected. max Using 20cm as a reference, define the slope k of the lower cone segment. 下 Let k be the ratio of the radial thickness variation to the axial length. 下=20 / 30≈0.667, corresponding to an angle of approximately 56.3° between the lower cone surface and the horizontal plane, and an angle of approximately 33.7° with the axis; define the slope k of the upper cone segment. 上 =t max / L 上 (L) 上 (where L is the axial length of the upper conical segment), the angle β between the inclined plane of the upper conical segment and the horizontal plane is β = arctan(L / 2π). 上 / t max The critical condition for effective sediment prevention is that β is greater than the underwater angle of repose φ of the sediment in the pore, i.e., L_ 上 >t max ·tan(φ). In bored pile construction, the underwater angle of repose of the mud carried by the drilling mud is generally between 28° and 35°. Taking fine sand (particle size 0.075-0.25mm, φ≈30°) as the critical anti-deposition particle size, the minimum axial length L of the upper cone section is... 上 Must satisfy: L 上 >20×tan30°≈11.5cm; Preferably, take L 上 With a particle size not less than 15cm, corresponding to an inclination angle of approximately 36.9°, it can effectively prevent silt and sand particles with a diameter not less than 0.075mm and larger from accumulating above the regulating ring 2; when L 上 When the slope is 20cm, the inclination angle reaches 45°, which has an anti-deposition effect on fine-grained mud and sand with a particle size of not less than 0.02mm, and is applicable to a wider range of strata.

[0070] Under the constraints of geometric relations, the slope k of the lower cone segment 下 , slope k of the upper cone segment 上 With the maximum ring thickness t max The following relationship must be satisfied between them: axial length L of the lower cone segment 下 =t max / k 下 axial length L of the upper conical segment 上 = t max / k 上 The total axial length L of the conical adjusting ring 2 总 =L 下 +L 上 = t max ·(1 / k) 下 +1 / k 上 Taking the optimal parameter as an example, k 下 =2 / 3, t max =20cm, L 下 =30cm; take k 上 =4 / 3 (L) 上 When L = 15cm), 总 =45cm; take k 上 =1 (L 上When L = 20cm), 总 =50cm. The above geometric relationship clarifies the operable conversion relationship between the slope of the lower cone segment, the slope of the upper cone segment, and the maximum thickness, allowing k to be flexibly selected according to different pile diameters and geological conditions. 上 The specific values ​​are determined by controlling the overall axial dimension of the regulating ring 2 while ensuring the anti-deposition function.

[0071] In one embodiment, such as Figure 3 As shown, the ground control system 5 consists of a fixed chuck 5.1 and a reel 5.2. The fixed chuck 5.1 is fixed to the drill rod 4 by a clip, and the reel 5.2 is mounted on the fixed chuck 5.1. The axial transmission component 3 is a steel wire rope. The upper end of the steel wire rope is fixed to the reel 5.2 by a rope clamp, and the lower end of the steel wire rope is connected to the adjusting ring 2, so that the drive of the reel 5.2 is transmitted as the axial displacement of the adjusting ring 2. Due to the limitations of the field construction environment, the use of the above-mentioned ground control system 5, which does not require electric drive, is more convenient and faster.

[0072] In one embodiment, a flexible sheath is wrapped around the outside of the wire rope. The flexible sheath can be a rubber hose or a braided sheath to prevent the wire rope from being worn and corroded by mud and sand particles in the hole, while not affecting the axial transmission and bending deformation of the wire rope.

[0073] Of course, in practical applications, if conditions permit, a motor or hydraulic mechanism can be set in the ground control system 5 to drive the axial transmission component 3, i.e., the wire rope, so as to achieve precise control of the axial displacement of the adjusting ring 2.

[0074] Considering the stability of the pile borehole wall, the pile foundation construction equipment described in this application is recommended for toothed pile construction in general cohesive soils, and should be used with caution in sandy soils and soft soils. To prevent borehole collapse, high-quality mud with a high specific gravity should be prepared. The distance between the upper and lower teeth of the pile should be greater than 1m.

[0075] Secondly, the aforementioned pile foundation construction equipment is used to create grooves in the pile hole wall, resulting in the shape of the toothed pile hole as shown in the image. Figure 4 As shown, a groove 7 is formed in the stratum 8 of the pile hole wall in pile hole 6. The specific steps of the construction method are as follows:

[0076] S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter;

[0077] S2. The ground control system 5 drives the adjusting ring 2 to move downward relative to the drill rod, controlling the downward speed of the adjusting ring 2 relative to the drill rod 4 to match the drilling speed of the drill rod 4 relative to the ground. The radially telescopic toothed cutter 1.2 then gradually extends radially. When the adjusting ring 2 descends to the predetermined position, the radially telescopic toothed cutter 1.2 reaches its maximum extension, and the ground control system 5 stops driving the adjusting ring 2. The drill rod 4 continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation of the pile tooth section hole wall.

[0078] S3. After reaching the designed bottom depth of the pile teeth, the ground control system 5 reverses the driving of the adjustment ring 2, raises the adjustment ring 2, and stops driving after raising it to the predetermined position. The radially telescopic tooth cutter 1.2 retracts to within the large circle 1.1 of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling.

[0079] S4. Repeat steps S1 to S3 according to the design requirements to form multiple pile hole wall grooves 7 at different hole depths in sequence. The hole depth spacing between adjacent groove sections shall not be less than 1m.

[0080] According to the preferred parameters of the aforementioned equipment, the adjusting ring 2 is a conical adjusting ring. The axial length from the thickest part in the middle to the thinnest part at the bottom of the conical adjusting ring is 30cm, the maximum ring thickness is 20cm, and the thickness of the ring at the thinnest part at the bottom and top is no more than 0.5mm. Based on a pile diameter of 100cm, the maximum single-sided extension of the radially telescopic toothed cutter 1.2 is 20cm, which increases the maximum diameter of the pile hole by 40cm compared to the normal drilling diameter.

[0081] Specifically, according to the preferred parameters described in the aforementioned equipment, the pile foundation construction equipment described above is used to form grooves in the pile hole wall. The specific steps of the construction method are as follows:

[0082] S1. Prepare high-quality mud with appropriate specific gravity for wall protection, start the drilling rig, and drill to the depth of the preset enlargement section with normal pile diameter. During the drilling process, the drill bit 1 rotates with the drill rod 4, and the radially telescopic toothed cutter 1.2 is in a retracted state and stored within the large circle 1.1 of the drill bit, so as not to cause enlargement cutting to the hole wall.

[0083] S2. After reaching the preset diameter expansion section depth, the operator drives the adjusting ring 2 to move downward relative to the drill rod 4 via the ground control system 5. Specifically, the operator rotates the sheave 5.2, which pulls the adjusting ring 2 downward via the axial transmission component 3 (wire rope). This controls the downward speed of the adjusting ring 2 relative to the drill rod 4 to match the drilling speed of the drill rod 4 relative to the ground, ensuring that the lower conical section of the tapered adjusting ring continuously presses against the rear side of the radially retractable toothed cutter 1.2. Under the support and tangential limiting action of the toothed cutter rear tray 1.3, the radially retractable toothed cutter 1.2 gradually and smoothly extends radially as the adjusting ring 2 descends. The drill bit extends to the large circle 1.1, cutting and enlarging the borehole diameter of the stratum 8 on the borehole wall. When the adjusting ring 2 descends to the predetermined position, the radially extendable toothed cutter 1.2 reaches its maximum extension (based on a pile diameter of 100cm, the maximum single-sided extension is 20cm, increasing the maximum diameter of the pile hole to 140cm), stopping the ground control system 5 from driving the adjusting ring 2. Thereafter, the fixed chuck 5.1 maintains the axial positioning of the adjusting ring 2, and the drill rod 4 drives the drill bit 1 to continue drilling to the designed bottom depth of the pile tooth with the enlarged pile diameter, completing the formation of the arc-shaped groove 7 in the borehole wall of the pile tooth section, with a groove tooth height of 30cm.

[0084] S3. After reaching the designed bottom depth of the pile teeth, the ground control system 5 reverses the driving of the adjusting ring 2. The operator rotates the reel 5.2 in the opposite direction, and the adjusting ring 2 is lifted to the predetermined position via the axial transmission component 3, after which the driving stops. The conical adjusting ring releases the radial limit on the rear side of the radially retractable toothed cutter 1.2. Under the radial resistance of the formation 8 in the borehole wall, the radially retractable toothed cutter 1.2 retracts centripetally to within the drill bit's large circle 1.1. The toothed cutter's rear tray 1.3 moves upward and reset synchronously with the adjusting ring 2. The drill bit 1 returns to the normal pile diameter and continues drilling downward.

[0085] S4. Repeat steps S1 to S3 according to the design requirements to sequentially form multiple pile hole wall grooves 7 at different hole depths. The hole depth distance between adjacent groove sections should not be less than 1m to ensure the stability of the hole wall between grooves and avoid collapse due to local weakening of the hole wall between adjacent groove sections. During the entire groove forming process, there is no need to remove the drill bit 1 midway. All diameter expansion and retraction operations are completed by the operator on the ground through the ground control system 5.

[0086] Therefore, the groove 7 of the pile hole wall obtained by the above construction method is arc-shaped with a flat bottom. When the normal pile diameter is 100cm, the maximum pile diameter is 140cm and the tooth height is 30cm.

[0087] Thirdly, the construction method of enlarging the pile bottom hole using the aforementioned pile foundation construction equipment yields the pile hole morphology of the toothed pile segment and the enlarged pile segment as follows: Figure 5 As shown, the enlarged pile bottom section of pile hole 6 is constructed by enlarging the pile bottom. The specific steps of the construction method are as follows:

[0088] S1. Drill to the designed enlargement starting depth using the normal pile diameter;

[0089] S2. The ground control system 5 drives the adjusting ring 2 to move downward relative to the drill rod, and controls the downward speed of the adjusting ring 2 relative to the drill rod 4 to match the drilling speed of the drill rod 4 relative to the ground. The radially telescopic toothed cutter 1.2 gradually extends radially until the adjusting ring 2 descends to the predetermined position and the radially telescopic toothed cutter 1.2 reaches the maximum extension amount, and the ground control system 5 stops driving the adjusting ring 2.

[0090] S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter;

[0091] S4. After reaching the pile tip depth, the ground control system 5 reverses the driving of the adjustment ring 2, raises the adjustment ring 2, and stops driving after raising it to the predetermined position. During the drilling process, the radially telescopic toothed cutter 1.2 retracts to within the drill bit's large circle 1.1 under the resistance of the formation on the borehole wall, thus completing the drilling of the enlarged bottom pile section.

[0092] According to the preferred parameters of the aforementioned equipment, the adjusting ring 2 is a conical adjusting ring. The axial length from the thickest part in the middle to the thinnest part at the bottom of the conical adjusting ring is 30cm, the maximum ring thickness is 20cm, and the thickness of the ring at the thinnest part at the bottom and top is no more than 0.5mm. Based on a pile diameter of 100cm, the maximum single-sided extension of the radially telescopic toothed cutter 1.2 is 20cm, which increases the maximum diameter of the pile hole by 40cm compared to the normal drilling diameter.

[0093] Specifically, according to the preferred parameters described in the aforementioned equipment, the pile foundation construction equipment described above is used to enlarge the pile bottom hole. The specific steps of the construction method are as follows:

[0094] S1. Prepare high-quality mud with appropriate specific gravity for wall protection, start the drilling rig, and drill to the designed enlargement starting depth with normal pile diameter. During the drilling process, the drill bit 1 rotates with the drill rod 4, and the radially telescopic toothed cutter 1.2 is in a retracted state and stored within the drill bit's large circle 1.1, without causing enlargement cutting on the hole wall.

[0095] S2. After reaching the designed initial depth for underreaming, the operator on the ground uses the ground control system 5 to drive the adjusting ring 2 to move downward relative to the drill rod 4. Specifically, the operator rotates the sheave 5.2, which pulls the adjusting ring 2 downward via the axial transmission component 3 (wire rope). This controls the downward speed of the adjusting ring 2 relative to the drill rod 4 to match the drilling speed of the drill rod 4 relative to the ground, ensuring that the lower conical section of the tapered adjusting ring continuously pushes against the rear side of the radially retractable toothed cutter 1.2. The radially retractable toothed cutter 1.2 is supported and tangentially limited by the toothed cutter rear tray 1.3. As the adjusting ring 2 descends, it gradually and smoothly extends radially outward by the drill bit's large circle 1.1, cutting and enlarging the diameter of the borehole wall strata 8 in the enlarged section; until the adjusting ring 2 descends to the predetermined position and the radially telescopic toothed cutter 1.2 reaches its maximum extension (based on a pile diameter of 100cm, the maximum single-sided extension is 20cm, and the diameter of the pile hole in the enlarged section increases to 140cm), the driving of the adjusting ring 2 by the ground control system 5 is stopped; the fixed chuck 5.1 maintains the axial positioning of the adjusting ring 2, and the radially telescopic toothed cutter 1.2 maintains its maximum extension state;

[0096] S3. Keep the position of the adjusting ring 2 unchanged, and the drill rod 4 drives the drill bit 1 to continue drilling downward with the enlarged pile diameter (140cm), continuously cutting the stratum 8 of the hole wall in the enlarged bottom section until the designed depth of the pile end is reached, thus completing the equal diameter enlargement of the bottom section; the axial length of the enlarged bottom section is determined by the difference between the initial depth of the enlarged bottom section and the designed depth of the pile end, and can be flexibly adjusted according to the engineering design requirements;

[0097] S4. After reaching the designed depth at the pile tip, stop drilling. Drive the adjusting ring 2 in the reverse direction through the ground control system 5. The operator rotates the reel 5.2 in the reverse direction. After lifting the adjusting ring 2 to the predetermined position through the axial transmission component 3, stop driving. The conical adjusting ring releases the radial limit on the rear side of the radially retractable toothed cutter 1.2. Under the radial resistance of the stratum 8 in the borehole wall, the radially retractable toothed cutter 1.2 retracts centripetally to within the large circle 1.1 of the drill bit. The toothed cutter rear tray 1.3 moves upward and reset synchronously with the adjusting ring 2. Then start lifting the drill. The drill bit 1 returns to the normal pile diameter (100cm). No scraping occurs on the borehole wall during the lifting process, completing the hole formation of the enlarged bottom pile section.

[0098] Therefore, the diameter of the enlarged-base pile segment obtained by the above construction method is 140cm.

[0099] Fourthly, by utilizing the aforementioned pile foundation construction equipment, a composite hole is simultaneously formed within the same pile hole, consisting of a grooved section of the pile hole wall and an enlarged pile bottom section, resulting in pile hole morphologies for the toothed pile section and the enlarged pile bottom section, as shown in the figure. Figure 5 As shown, multiple pile hole wall grooves 7 are formed on the stratum 8 of the pile hole wall in the toothed pile section of pile hole 6. The pile bottom is enlarged in the enlarged pile section of pile hole 6. The specific steps of the construction method are as follows:

[0100] In one drilling process, one or more pile hole wall grooves 7 are formed sequentially according to the method described above:

[0101] S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter;

[0102] S2. The ground control system drives the adjusting ring to move downward relative to the drill rod, controlling the downward speed of the adjusting ring relative to the drill rod to match the drilling speed of the drill rod relative to the ground. The radially telescopic cutting tooth extends radially accordingly. When the adjusting ring descends to the predetermined position, the radially telescopic cutting tooth reaches its maximum extension, and the ground control system stops driving the adjusting ring. The drill rod continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation on the hole wall of the pile tooth section.

[0103] S3. After reaching the designed bottom depth of the pile teeth, the adjustment ring is reversed through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. The radially telescopic tooth cutter retracts to the large circle of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling.

[0104] S4. Repeat steps S1 to S3 according to the design requirements to form multiple pile hole wall grooves at different hole depths in sequence. The hole depth spacing between adjacent groove sections shall not be less than 1m.

[0105] Continue drilling to the initial depth of the enlarged section at the normal pile diameter, and then complete the hole formation of the enlarged section at the pile bottom according to the following method:

[0106] S1. Drill to the designed enlargement starting depth using the normal pile diameter;

[0107] S2. Drive the adjusting ring to move downward relative to the drill pipe through the ground control system, and control the downward speed of the adjusting ring relative to the drill pipe to match the drilling speed of the drill pipe relative to the ground. The radially telescopic toothed cutter gradually extends radially until the adjusting ring descends to the predetermined position and the radially telescopic toothed cutter reaches the maximum extension amount, and then stop the ground control system from driving the adjusting ring.

[0108] S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter;

[0109] S4. After reaching the pile tip depth, the adjustment ring is reverse-driven through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. During the drilling process, the radially telescopic toothed cutter retracts to within the large circle of the drill bit under the resistance of the formation on the borehole wall, thus completing the hole formation of the enlarged bottom pile section.

[0110] All diameter expansion operations are completed by driving the axial movement of the adjustment ring through the ground control system, without the need to remove the drill bit midway, ultimately forming a composite pile hole shape that combines the toothed pile segment with the enlarged bottom pile segment.

[0111] Continue drilling to the initial depth of the enlarged section at the normal pile diameter, and then complete the hole formation of the enlarged section at the pile bottom according to the following method:

[0112] S1. Drill to the designed enlargement starting depth using the normal pile diameter;

[0113] S2. The ground control system 5 drives the adjusting ring 2 to move downward relative to the drill rod, and controls the downward speed of the adjusting ring 2 relative to the drill rod 4 to match the drilling speed of the drill rod 4 relative to the ground. The radially telescopic toothed cutter 1.2 gradually extends radially until the adjusting ring 2 descends to the predetermined position and the radially telescopic toothed cutter 1.2 reaches the maximum extension amount, and the ground control system 5 stops driving the adjusting ring 2.

[0114] S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter;

[0115] S4. After reaching the pile tip depth, the ground control system 5 reverses the driving of the adjustment ring 2, raises the adjustment ring 2, and stops driving after raising it to the predetermined position. During the drilling process, the radially telescopic toothed cutter 1.2 retracts to within the drill bit's large circle 1.1 under the resistance of the formation on the borehole wall, thus completing the drilling of the enlarged bottom pile section.

[0116] In the construction method described in the fourth aspect above, all diameter expansion operations are completed by driving the adjustment ring 2 axially through the ground control system 5, without having to remove the drill bit midway, ultimately forming a composite pile hole shape that combines the toothed pile segment with the expanded bottom pile segment with the locally expanded diameter of the pile body.

[0117] In the above construction method, the downward speed of the control ring 2 relative to the drill rod 4 is synchronized with the drilling speed of the drill rod 4 relative to the ground. This synchronization can be achieved by the following means: setting depth marks on the reel 5.2 of the ground control system or on the drill rod 4, and the operator controls the reel 5.2 to release the line length and the drilling depth of the drill rod 4 in real time according to the marks, so that the downward speed of the control ring 2 relative to the drill rod 4 is synchronized with the drilling speed of the drill rod 4 relative to the ground; or setting a mechanical linkage mechanism between the reel 5.2 and the drilling rig feed system to achieve linkage between the two.

[0118] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A pile foundation construction device with segmented adjustable pile hole diameter, characterized in that: It includes a drill bit with radially retractable toothed cutters, an adjusting ring fitted onto the center rod of the drill bit, and a ground control system fixed to the drill rod; The adjusting ring engages with the rear side of the radially retractable toothed cutter to limit the radial extension of the radially retractable toothed cutter. The ground control system is connected to the adjusting ring via an axial transmission component. The adjusting ring can move axially relative to the drill rod under the drive of the axial transmission component, thereby controlling the radially telescopic toothed cutter to extend or retract outside or inside the drill bit's large circle, thus realizing segmented adjustment of the pile hole diameter.

2. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 1, characterized in that: The drill bit is a three-wing scraper fishtail drill bit, with at least two sets of radially retractable toothed cutters installed inside the large circle of the drill bit. The cutting edge of the radially retractable toothed cutter is crescent-shaped, and the arc surface faces the direction of rotation of the drill bit.

3. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 2, characterized in that: The radially retractable toothed cutter is configured in three groups, evenly distributed along the circumference of the drill bit's large ring. Each group of radially retractable toothed cutters corresponds to a radial opening on the drill bit's large ring and extends or retracts radially synchronously under the push of the adjusting ring. An annular toothed cutter rear tray is also provided at the adjusting ring, which supports and tangentially limits the radially retractable toothed cutter.

4. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 1, characterized in that: The adjusting ring is a conical adjusting ring, with the thickest part in the middle. It gradually decreases in thickness from the thickest part in the middle to the thinnest part at the bottom, forming a lower conical section, and gradually decreases in thickness from the thickest part in the middle to the thinnest part at the top, forming an upper conical section. The lower conical section contacts the rear side of the radially retractable toothed cutter through its conical surface, and is used to control the radial extension of the radially retractable toothed cutter. The upper conical section is used to prevent mud and sand in the hole from accumulating above the conical adjusting ring and blocking the annular gap between the conical adjusting ring and the drill bit center rod.

5. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 4, characterized in that: The axial length from the thickest part in the middle to the thinnest part at the bottom of the conical adjusting ring is 30cm, the maximum ring thickness is 20cm, and the thickness of the ring at the thinnest part at the bottom and top is no more than 0.5mm. Based on a pile diameter of 100cm, the maximum single-sided extension of the radially telescopic toothed cutter is 20cm, which increases the maximum diameter of the pile hole by 40cm compared to the normal drilling diameter.

6. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 1, characterized in that: The ground control system includes a fixed chuck that is fixed to the drill rod by a buckle and a reel set on the fixed chuck; the axial transmission component is a steel wire rope, the upper end of which is fixed to the reel by a rope clamp, and the lower end of which is connected to an adjusting ring, so that the drive of the reel is transmitted as the axial displacement of the adjusting ring.

7. The pile foundation construction equipment with segmented adjustable pile hole diameter as described in claim 6, characterized in that: The steel wire rope is covered with a flexible sheath on the outside.

8. A construction method for forming grooves in the pile hole wall using the pile foundation construction equipment described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter; S2. The ground control system drives the adjusting ring to move downward relative to the drill rod, controlling the downward speed of the adjusting ring relative to the drill rod to match the drilling speed of the drill rod relative to the ground. The radially telescopic cutting tooth gradually extends radially accordingly. When the adjusting ring descends to the predetermined position, the radially telescopic cutting tooth reaches its maximum extension, and the ground control system stops driving the adjusting ring. The drill rod continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation on the hole wall of the pile tooth section. S3. After reaching the designed bottom depth of the pile teeth, the adjustment ring is reversed through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. The radially telescopic tooth cutter retracts to the large circle of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling. S4. Repeat steps S1 to S3 according to the design requirements to form multiple grooves in the pile hole wall at different hole depths. The hole depth spacing between adjacent groove sections shall not be less than 1m.

9. A construction method for enlarging pile bottom hole formation using the pile foundation construction equipment described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Drill to the designed enlargement starting depth using the normal pile diameter; S2. Drive the adjusting ring to move downward relative to the drill pipe through the ground control system, and control the downward speed of the adjusting ring relative to the drill pipe to match the drilling speed of the drill pipe relative to the ground. The radially telescopic toothed cutter gradually extends radially until the adjusting ring descends to the predetermined position and the radially telescopic toothed cutter reaches the maximum extension amount, and then stop the ground control system from driving the adjusting ring. S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter; S4. After reaching the pile tip depth, the adjustment ring is reverse-driven through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. During the drilling process, the radially telescopic toothed cutter retracts to within the large circle of the drill bit under the resistance of the formation on the borehole wall, thus completing the hole formation of the enlarged bottom pile section.

10. A method for constructing a composite hole in which the pile foundation construction equipment described in any one of claims 1 to 7 simultaneously completes the grooved section of the pile hole wall and the enlarged pile bottom section within the same pile hole, characterized in that: In a single drilling process, one or more grooves in the pile hole wall are formed sequentially according to the method described below: S1. Drill to the preset hole depth position of the enlarged diameter section with the normal pile diameter; S2. The ground control system drives the adjusting ring to move downward relative to the drill rod, controlling the downward speed of the adjusting ring relative to the drill rod to match the drilling speed of the drill rod relative to the ground. The radially telescopic cutting tooth gradually extends radially accordingly. When the adjusting ring descends to the predetermined position, the radially telescopic cutting tooth reaches its maximum extension, and the ground control system stops driving the adjusting ring. The drill rod continues to drill to the designed bottom depth of the pile tooth, completing the groove hole formation on the hole wall of the pile tooth section. S3. After reaching the designed bottom depth of the pile teeth, the adjustment ring is reversed through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. The radially telescopic tooth cutter retracts to the large circle of the drill bit under the resistance of the stratum, and the normal pile diameter is restored to continue drilling. S4. Repeat steps S1 to S3 according to the design requirements to form multiple pile hole wall grooves at different hole depths in sequence. The hole depth spacing between adjacent groove sections shall not be less than 1m. Continue drilling to the initial depth of the enlarged section at the normal pile diameter, and then complete the hole formation of the enlarged section at the pile bottom according to the following method: S1. Drill to the designed enlargement starting depth using the normal pile diameter; S2. Drive the adjusting ring to move downward relative to the drill pipe through the ground control system, and control the downward speed of the adjusting ring relative to the drill pipe to match the drilling speed of the drill pipe relative to the ground. The radially telescopic toothed cutter gradually extends radially until the adjusting ring descends to the predetermined position and the radially telescopic toothed cutter reaches the maximum extension amount, and then stop the ground control system from driving the adjusting ring. S3. Continue drilling downwards to the designed depth at the pile tip using the enlarged pile diameter; S4. After reaching the pile tip depth, the adjustment ring is reverse-driven through the ground control system. The adjustment ring is raised to the predetermined position and then the drive is stopped. During the drilling process, the radially telescopic toothed cutter retracts to within the large circle of the drill bit under the resistance of the formation on the borehole wall, thus completing the hole formation of the enlarged bottom pile section. All diameter expansion operations are completed by driving the axial movement of the adjustment ring through the ground control system, without the need to remove the drill bit midway, ultimately forming a composite pile hole shape that combines the toothed pile segment with the enlarged bottom pile segment.

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