Drilling device and method for cast-in-place pile construction

Abstract

The present application relates to the field of drilling technology, and specifically to a drilling device and method for bored pile construction, wherein the drilling rig drives the drilling assembly to rotate and lift through a drive shaft. During the drilling process, the drilling unit is responsible for feeding downward to perform the actual drilling operation; at the same time, the anti-shrinkage unit is installed above the drilling unit and connected to the drive shaft, so that the anti-shrinkage unit can actively and / or spontaneously expand outward along the radial direction of the drive shaft during drilling, thereby closely fitting the inner wall of the hole and effectively preventing the occurrence of shrinkage holes. When the drilling operation is completed, the anti-shrinkage unit can shrink back to its original position, which is convenient for the lifting and moving of the device and is ready for the next stage of construction. The present application not only improves the efficiency and quality of the drilling operation, but also effectively solves the shrinkage hole problem that is prone to occur in traditional drilling construction.

Description

Technical Field

[0001] The present application relates to the technical field of drilling, and in particular to a drilling device and method for cast-in-place pile construction. Background Art

[0002] In the field of civil engineering, cast-in-place piles are an important foundation construction method, often used in large-scale projects such as bridges, high-rise buildings, and port terminals. Their construction quality and stability are directly related to the safety and durability of the entire engineering structure. However, traditional drilling construction equipment generally has shrinkage after completing the drilling operation. This problem has become one of the key factors restricting the quality of pile foundation construction and the progress of the project.

[0003] The shrinkage phenomenon is caused by the interweaving influence of multiple factors, especially in the strata with high permeability soft soil, silt or plastic soil containing a large amount of sandy geology. The mechanical properties of the soil are poor and it is easy to be squeezed and deformed by external forces. When the drilling operation is in progress, the rotation and advancement of the drill will exert a certain pressure on the soil on the hole wall, causing the soil on the hole wall to squeeze into the hole, thereby forming shrinkage. The shrinkage phenomenon will not only cause the diameter of the pile foundation to shrink, unable to meet the design requirements, but also seriously affect the bearing capacity of the pile foundation, which may cause serious quality problems such as pile body tilting and fracture, posing a huge threat to the stability and safety of the entire engineering structure. Summary of the invention

[0004] One of the purposes of this application is to provide a drilling method for cast-in-place pile construction; the second purpose is to propose a device to solve the problem that shrinkage hole phenomenon is easy to occur in traditional drilling construction, resulting in the reduction of the diameter of the pile foundation hole and failure to meet the design requirements.

[0005] In order to achieve the above purpose, the technical solution adopted in this application is as follows:

[0006] On the one hand, the present application proposes a drilling method for cast-in-place pile construction, the drilling method comprising the following steps:

[0007] Casing installation: Drill a pre-set hole with the same diameter as the casing, and accurately lower and secure the casing;

[0008] Mud preparation and circulation: Prepare mud with specific gravity, viscosity and sand content according to the formation conditions, and maintain the stability of the mud in the hole through positive circulation and / or reverse circulation;

[0009] Hole construction: Use cast-in-place pile drilling that can prevent shrinkage to carry out drilling operations, and adjust drilling parameters and mud properties to ensure hole quality and hole wall stability;

[0010] Hole cleaning construction: After the hole is formed, the primary and secondary hole cleaning are carried out to reduce the mud density and remove the sediment at the bottom of the hole;

[0011] Lowering the steel cage: The steel cage is designed to be circular and is lowered in sections using a crane. The guide tubes are placed and concrete is poured.

[0012] On the other hand, the present application also proposes a drilling device for cast-in-place pile construction, which is applied to the aforementioned drilling method, and the device comprises:

[0013] A drilling rig, a drive shaft and a drilling assembly, wherein the drilling assembly is connected to the drilling rig via the drive shaft, and the drilling rig can drive the drilling assembly to rotate and / or rise and fall;

[0014] The drilling assembly includes an anti-shrinkage unit and a drilling unit, wherein the anti-shrinkage unit is used to prevent the hole from shrinking and the drilling unit can be fed downward to drill the hole;

[0015] The anti-shrinkage unit is installed above the drilling unit, and the anti-shrinkage unit is connected to the driving shaft;

[0016] The anti-shrinkage unit has a tendency to actively expand outwardly in the radial direction of the drive shaft and / or a tendency to spontaneously expand outwardly in the radial direction of the drive shaft.

[0017] According to the above technical solution, the drilling rig drives the drilling assembly to rotate and lift through the driving shaft. The drilling assembly is mainly composed of an anti-shrinkage unit and a drilling unit. During the drilling process, the drilling unit is responsible for feeding downward to perform actual drilling operations. At the same time, the anti-shrinkage unit is installed above the drilling unit and is connected to the driving shaft. This design enables the anti-shrinkage unit to actively and / or spontaneously expand outward along the radial direction of the driving shaft during drilling, so as to fit closely to the inner wall of the hole and effectively prevent the occurrence of shrinkage holes. When the drilling operation is completed, the anti-shrinkage unit can be retracted back to its original position, which is convenient for the lifting and moving of the device and is ready for the next stage of construction. This application not only improves the efficiency and quality of the drilling operation, but also effectively solves the shrinkage hole problem that is prone to occur in traditional drilling construction.

[0018] Further, the anti-shrinkage unit includes an active expansion structure, which includes a mounting seat, an expansion block, a telescopic rod and a driving structure. There are multiple expansion blocks and telescopic rods, and each expansion block is distributed around the mounting seat, and each expansion block is enclosed together to form an annular structure.

[0019] A connecting piece is provided between adjacent expansion blocks, and each telescopic rod is located between the connecting piece and the mounting seat and is connected to the connecting piece;

[0020] The driving structure is coaxially rotatably mounted on the mounting seat, and the driving structure is used to drive the expansion block to expand outwards or contract inwards.

[0021] Further, the driving structure includes a bracket part and a driving part, and the driving part is used to drive the bracket part to rotate;

[0022] The bracket portion includes a central axis, a first bracket and a second bracket, wherein the first bracket and the second bracket are mounted on the central axis, and the first bracket and the second bracket are used to be connected to the corresponding connecting member.

[0023] According to the above technical solution, when the drilling operation is started, the driving structure starts to work. The driving structure is coaxially mounted on the mounting seat and generates rotational or linear motion through mechanical transmission or hydraulic drive. This motion is transmitted to the expansion block connected to the driving structure. There are multiple expansion blocks, which are evenly distributed around the mounting seat and together form a ring structure. Each expansion block is connected to the telescopic rod through a connecting piece, and the other end of the telescopic rod is fixed on the mounting seat. This design enables the expansion block to expand or contract along the radial direction of the mounting seat under the action of the driving structure; when the driving structure drives the expansion block to expand outward, the telescopic rod is extended accordingly to provide the necessary support force for the expansion block. At the same time, the connectors between adjacent expansion blocks also play a role in transmitting force and maintaining structural stability. In this way, the entire annular structure can fit tightly against the inner wall of the hole, effectively preventing the occurrence of shrinkage. On the contrary, when the shrinkage-proof unit needs to be retracted, the driving structure will move in the opposite direction, driving the expansion block to retract inward. At this time, the telescopic rod will also shorten accordingly to adapt to the retraction of the expansion block. In this way, the shrinkage-proof unit can be easily retracted back to its original position after the drilling operation is completed, which is convenient for the lifting and moving of the device. The active expansion structure of the shrinkage-proof unit achieves a tight fit and effective support to the inner wall of the hole through the coordinated action of the driving structure, expansion block, telescopic rod and connector, thereby greatly improving the stability and quality of the drilling operation and facilitating the subsequent placement of the steel cage.

[0024] Furthermore, the connecting member includes a connecting block and two connecting rods, the two connecting rods are respectively hinged to two ends of the connecting block, and the other ends of the two connecting rods are hinged to the corresponding expansion blocks.

[0025] According to the above technical solution, the connecting piece realizes a stable connection between the expansion blocks through the connecting block and the two connecting rods. The two connecting rods are respectively hinged to the two ends of the connecting block and then hinged to the corresponding expansion block to form a flexible connection structure. During the expansion or contraction process, the connecting rod can adaptively adjust the angle as the expansion block moves, thereby achieving the purpose of expanding outward or contracting inward.

[0026] Further, the first bracket includes a first connecting rod, a second connecting rod, a third connecting rod, a fourth connecting rod and a fifth connecting rod, the second connecting rod and the third connecting rod are hinged at both ends of the first connecting rod, the fourth connecting rod is fixed to the first connecting rod, and the fourth connecting rod is hinged to the fifth connecting rod;

[0027] The second bracket comprises a sixth connecting rod, a seventh connecting rod, an eighth connecting rod, a ninth connecting rod and a tenth connecting rod, wherein the seventh connecting rod and the eighth connecting rod are hinged to the sixth connecting rod, and one end of the ninth connecting rod is fixed to the sixth connecting rod, and the other end is hinged to the tenth connecting rod;

[0028] The middle parts of the first connecting rod and the fourth connecting rod are fixed on the central shaft;

[0029] The number of the connecting pieces is six, namely, connecting piece 1, connecting piece 2, connecting piece 3, connecting piece 4, connecting piece 5 and connecting piece 6;

[0030] Among them, the second connecting rod is hinged to the connecting member 1, the third connecting rod is hinged to the connecting member 4, and the fifth connecting rod is hinged to the connecting member 2; the eighth connecting rod is hinged to the connecting member 3, the seventh connecting rod is hinged to the connecting member 6, and the tenth connecting rod is hinged to the connecting member 5.

[0031] Further, the driving part is driving member 1 or driving member 2;

[0032] The first driving member comprises a first driving motor, a worm and a worm wheel, the worm wheel is coaxially connected to the central shaft, the worm is meshed with the worm wheel, and the driving motor is connected to the worm to drive the worm to rotate;

[0033] The second driving member includes a second driving motor, and the second driving motor is coaxially connected to the central axis.

[0034] According to the above technical solution, in solution 1, the driving part adopts driving member 1, whose core components include a first driving motor, a worm and a worm wheel. The worm wheel is coaxially connected to the central axis to form a fixed transmission relationship. The worm is meshed with the worm wheel, and the torque transmission and speed reduction are achieved through the meshing transmission of the worm wheel and worm.

[0035] When the first drive motor is started, it outputs rotational power and is connected to the worm through a transmission device such as a coupling, thereby driving the worm to rotate. Since the worm and the worm wheel are meshed, the rotation of the worm will drive the worm wheel to rotate synchronously. Since the worm wheel is coaxially connected to the central shaft, the rotation of the worm wheel will be directly transmitted to the central shaft, causing the central shaft to start rotating.

[0036] The rotation of the central axis will further drive the first bracket and the second bracket connected thereto to perform complex relative motion, and then drive each expansion block to perform corresponding expansion or contraction actions through the connecting piece. This transmission method has the advantages of compact structure, large transmission ratio and strong load-bearing capacity, and is suitable for occasions where precise control of rotation angle and torque is required.

[0037] Solution 2: Working principle of drive element 2

[0038] In the second scheme, the driving part adopts the second driving member, and its core component is the second driving motor. Different from the first scheme, the second driving motor is directly connected to the central shaft coaxially, forming a more direct transmission relationship.

[0039] When the second drive motor is started, it outputs rotational power and directly transmits it to the central shaft, causing the central shaft to start rotating. Since the second drive motor is coaxially connected to the central shaft, the rotation speed of the motor is consistent with the rotation speed of the central shaft, and there is no need to reduce or increase the speed through an additional transmission device.

[0040] The rotation of the central axis will also drive the first bracket and the second bracket to move relative to each other, and drive each expansion block to expand or contract accordingly through the connecting piece. This transmission method has the advantages of simple structure and high transmission efficiency, and is suitable for occasions requiring fast response and high speed.

[0041] Furthermore, the anti-shrinkage unit comprises a driven expansion structure, the number of the driven expansion structures is multiple, and each of the driven expansion structures is correspondingly mounted on one of the expansion blocks;

[0042] Each of the driven expansion structures can expand outwards or contract inwards;

[0043] When the drive shaft rotates, the driven expansion structure is in an outward expansion state, and when the drive shaft is stationary, the driven expansion structure is in an inward contraction state.

[0044] According to the above technical solution, when the drive shaft starts to rotate, the driven expansion structure is installed on the expansion block, so it will perform corresponding expansion actions as the expansion block moves. During the outward expansion of the driven expansion structure, they closely adhere to the inner wall of the hole, contact and rub against the inner wall of the hole, further enhancing the density of the inner wall of the hole to improve stability, and can effectively prevent the phenomenon of hole shrinkage during the drilling process, thus ensuring the quality and stability of drilling; when the drive shaft is stationary, the entire transmission system also stops working. At this time, the driven expansion structure will gradually return to the inward contraction state due to the loss of the action of the external driving force. This design enables the device to reduce the occupied space when not working, and the driven expansion structure can flexibly adjust the angle and position when subjected to an external driving force to adapt to the sizes and shapes of different holes, and can be applied to various drilling operations, with wide applicability and practicability.

[0045] Further, the driven expansion structure includes a slide bar, a mounting strip, a first connecting strip, a second connecting strip, and a third connecting strip. Both ends of the first connecting strip are respectively hinged to one end of the slide bar and one end of the mounting strip. Both ends of the second connecting strip are respectively hinged to the other end of the slide bar and the other end of the mounting strip. The first connecting strip and the second connecting strip are parallel to each other;

[0046] A slider and an elastic member are sleeved on the slide bar. The elastic member is used to drive the slider to move downward. One end of the third connecting strip is hinged to the slider, and the other end of the third connecting strip is hinged to the middle of the first connecting strip;

[0047] An extrusion column is connected to the mounting strip. The extrusion column is used to extrude the inner wall of the hole.

[0048] According to the above technical solution, the design of the driven expansion structure makes full use of the centrifugal force and the restoring force of the elastic member to achieve effective support for the inner wall of the hole, thereby avoiding the shrinkage phenomenon; when the drive shaft starts to rotate, the installation bar in the driven expansion structure is subjected to the centrifugal force, and this centrifugal force counteracts the pulling force of the elastic member. Due to the centrifugal force, the installation bar is pulled outward, thereby causing the first connecting bar and the second connecting bar hinged thereto to deform. These two groups of connecting bars are connected to the installation bar through a sliding rod, ensuring the stability of the installation bar during the outward expansion process. As the installation bar expands outward, the extrusion column connected thereto also moves outward. The material and design of the extrusion column enable it to be in close contact with the inner wall of the hole, and increase the density of the inner wall through friction, thereby improving the stability of the hole. This close fit and friction effectively prevent the shrinkage phenomenon of the hole during the drilling process. When the drive shaft stops rotating, the centrifugal force disappears. At this time, the tension of the elastic part begins to take effect, driving the mounting strip and the extrusion column to shrink inward. This shrinking action not only helps to reduce the space occupied by the device when not working, but also ensures that each component can be restored to its original state when used next time, making it easy to pull out of the hole. It has wide applicability and practicality.

[0049] Furthermore, the drilling unit includes a drill barrel and a drill cover, and the drill cover can be opened and closed and installed at the bottom of the drill barrel, and a notch is provided on the drill cover. During rotary drilling and feeding, mud residue can enter the drill barrel through the notch, and when the inside of the drill barrel reaches saturation, the drill barrel is lifted upward, the drill cover is opened, the mud residue in the drill barrel is discharged from the drill barrel, and then the drill cover is closed, and the drill barrel is lowered into the hole to continue rotary drilling, and this is repeated.

[0050] According to the above technical solution, the drilling unit design cleverly combines the functions of the drill barrel and the drill cover to achieve efficient and stable drilling operations. During the rotary drilling and feeding stage, the drill barrel is slowly lowered into the hole to be drilled. At this time, the drill cover remains closed to ensure the sealing inside the drill barrel. As the drill barrel rotates and feeds, the cutting edge at its bottom begins to contact the inner wall of the hole and cuts the soil or rock. Since there is a notch on the drill cover, these mud residues and debris can smoothly enter the drill barrel through the notch. As the rotary drilling operation continues, the mud residue inside the drill barrel gradually accumulates until it reaches a saturated state. At this time, in order to continue the operation and avoid blockage of the drill barrel, it is necessary to suspend the rotary drilling and lift the drill barrel upward. In the process of lifting the drill barrel, the drill cover is opened so that the mud residue inside the drill barrel is discharged smoothly. This step is usually completed by a specific opening mechanism or manual operation. After the mud residue is discharged, the drill cover is quickly closed to ensure the sealing inside the drill barrel during the subsequent lowering process. Afterwards, the drill tube is lowered into the hole again and the rotary drilling operation continues. During this process, the drilling unit repeats the actions of rotary drilling, lifting, slag removal and lowering until the predetermined drilling depth is reached. Through this working mechanism of the drilling unit, the cut mud and debris can be efficiently discharged from the drill tube. The opening and closing design of the drill cover allows the drill tube to remain closed during the lifting and lowering process to prevent the scattering of mud and debris, thereby further improving the operation efficiency and drilling quality.

[0051] Beneficial effects of this application:

[0052] 1. There are multiple expansion blocks, which are evenly distributed around the mounting seat and enclose a ring structure together. Each expansion block is connected to the telescopic rod through a connector, and the other end of the telescopic rod is fixed on the mounting seat. This design enables the expansion block to expand or contract along the radial direction of the mounting seat under the action of the driving structure; the connector between adjacent expansion blocks can play a role in transmitting force and maintaining structural stability, and the entire ring structure can fit tightly on the inner wall of the hole, effectively preventing the occurrence of shrinkage; on the contrary, when the shrinkage-proof unit needs to be contracted, the driving structure will move in the opposite direction, driving the expansion block to contract inward. At this time, the telescopic rod will also shorten accordingly to adapt to the contraction of the expansion block. In this way, the shrinkage-proof unit can be easily retracted back to its original position after the drilling operation is completed, which is convenient for the lifting and moving of the device. The active expansion structure of the shrinkage-proof unit achieves close fit and effective support to the inner wall of the hole through the synergistic effect of the driving structure, expansion block, telescopic rod and connector, thereby greatly improving the stability and quality of the drilling operation and facilitating the subsequent placement of the steel cage.

[0053] 2. The present application makes full use of the centrifugal force and the restoring force of the elastic member through the design of the driven expansion structure to achieve effective support for the inner wall of the hole, thereby avoiding the shrinkage phenomenon; when the drive shaft starts to rotate, the installation bar in the driven expansion structure is subjected to the centrifugal force, and this centrifugal force counteracts the pulling force of the elastic member. Due to the centrifugal force, the installation bar is pulled outward, thereby causing the first connecting bar and the second connecting bar hinged thereto to deform. These two groups of connecting bars are connected to the installation bar through a sliding rod, ensuring the stability of the installation bar during the outward expansion process. As the installation bar expands outward, the extrusion column connected thereto also moves outward. The extrusion column can be in close contact with the inner wall of the hole, and increase the density of the inner wall through friction, thereby improving the stability of the hole. This close fit and friction effectively prevent the shrinkage phenomenon of the hole during the drilling process. When the drive shaft stops rotating, the centrifugal force disappears. At this time, the tension of the elastic part begins to take effect, driving the mounting strip and the extrusion column to shrink inward. This shrinking action not only helps to reduce the space occupied by the device when not working, but also ensures that each component can be restored to its original state when used next time, making it easy to pull out of the hole. It has wide applicability and practicality.

[0054] Other advantages, objectives and features of the present application will be described to some extent in the subsequent description, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present application. The objectives and other advantages of the present application can be achieved and obtained through the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the overall structure of the cast-in-place pile drilling device used for anti-shrinkage holes in this application;

[0056] Figure 2 This is a schematic diagram of the partial structure of the drilling unit in the cast-in-place pile drilling device for anti-shrinkage holes in the present application;

[0057] Figure 3 A cross-sectional view of a drilling unit in a cast-in-place pile drilling device for preventing shrinkage holes in the present application;

[0058] Figure 4 This is a partial structural schematic diagram of the middle drilling unit in the cast-in-place pile drilling device for anti-shrinkage holes in the present application;

[0059] Figure 5 A schematic diagram of an anti-shrinkage unit and a driven expansion structure of a cast-in-place pile drilling device for anti-shrinkage holes in the present application;

[0060] Figure 6 The active expansion structure (see FIG. Figure 1 ) Schematic diagram;

[0061] Figure 7 The active expansion structure (see FIG. Figure 2 ) Schematic diagram;

[0062] Figure 8 It is a partial axial side schematic diagram of the active expansion structure in the cast-in-place pile drilling device for anti-shrinkage hole of the present application;

[0063] Fig. 9 A bottom view schematic diagram of the active expansion structure in the cast-in-place pile drilling device for preventing shrinkage holes in the present application;

[0064] Fig.10 This is a schematic diagram of the split active expansion structure in the cast-in-place pile drilling device for preventing shrinkage holes in the present application;

[0065] Fig.11 It is a partial structural schematic diagram of the active expansion structure in the cast-in-place pile drilling device for preventing shrinkage holes in the present application;

[0066] Fig.12 A schematic diagram of a first bracket of an active expansion structure in a cast-in-place pile drilling device for preventing shrinkage holes in the present application;

[0067] Fig.13 This is a schematic diagram of the disassembly of the first bracket in the cast-in-place pile drilling device for anti-shrinkage holes of the present application;

[0068] Fig.14 The invention is a cast-in-place pile drilling device for anti-shrinkage hole in this application. Figure 4 Schematic diagram of part A.

[0069] Among them, the drilling rig 1, the driving shaft 2, the anti-shrinkage unit 3, the active expansion structure 4, the mounting seat 41, the expansion block 42, the telescopic rod 43, the driven expansion structure 5, the sliding rod 51, the mounting bar 52, the first connecting bar 53, the second connecting bar 54, the third connecting bar 55, the slider 56, the elastic member 57, the extrusion column 58, the driving structure 6, the bracket part 61, the central axis 611, the first bracket 612, the first connecting rod 6121, the second connecting rod 6122, the third connecting rod 6123, the fourth connecting rod 6124, the fifth connecting rod Rod 6125, second bracket 613, sixth connecting rod 6131, seventh connecting rod 6132, eighth connecting rod 6133, ninth connecting rod 6134, tenth connecting rod 6135, driving unit 62, first driving motor 621, worm 622, worm wheel 623, connecting block 71, connecting piece 1 711, connecting piece 2 712, connecting piece 3 713, connecting piece 4 714, connecting piece 5 715, connecting piece 6 716, connecting support rod 72, drilling unit 8, drill barrel 81, drill cover 82, notch 821. DETAILED DESCRIPTION

[0070] The following will describe the implementation methods of the present application with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, not for limiting the scope of protection of the present application.

[0071] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0072] On the one hand, the present application proposes a drilling method for cast-in-place pile construction, the drilling method comprising the following steps:

[0073] Casing installation: Drill a pre-set hole with the same diameter as the casing, and accurately lower and secure the casing;

[0074] Specifically, use a drilling device to drill a hole with the same diameter as the casing, then lower the casing and align it, and press it down to a certain depth with the drilling device; after the casing is buried, check the center coordinates of the pile to ensure that the plane position deviation is no greater than the design requirements of the specification; after each casing is buried, take measures such as steel plate covering and railing protection to prevent people or debris from falling into the casing.

[0075] Mud preparation and circulation: Prepare mud with specific gravity, viscosity and sand content according to the formation conditions, and maintain the stability of the mud in the hole through positive circulation and / or reverse circulation;

[0076] When the soil layer in the bored pile area is sandy silt, medium sand, weathered granite, etc., mud needs to be injected into the pile foundation hole / hole during drilling to improve the stability of the pile foundation hole and avoid shrinkage. When preparing the mud required for drilling holes by the drilling device, first clean the mud pool, add a certain amount of bentonite and soda ash, and mix them by pumping water with a mud pump. During the process, check whether the mud performance indicators meet the requirements and make adjustments at any time.

[0077] The specific mud performance indicators are shown in Table 1 below:

[0078] Table 1, Mud performance indicators

[0079]

[0080] Hole forming construction: Use a drilling device that can prevent shrinkage to perform drilling operations, and adjust drilling parameters and mud properties to ensure hole forming quality and hole wall stability;

[0081] After the drilling rig 1 is in place, adjust its verticality to ensure that the center of the drilling assembly is aligned with the center of the cross line of the casing. During the drilling process, control the footage speed according to the geological conditions. In the formation that is easy to shrink, appropriately increase the number of hole sweeps to prevent shrinkage. When entering the sand layer, slow down the footage speed, increase the mud viscosity, and reduce the footage of each drilling assembly return to ensure the stability of the hole wall.

[0082] During the drilling process, various parameters of the drilling process are recorded, such as adding a driving rod, drilling depth, geological characteristics, mechanical equipment damage, obstacles, etc. During the drilling process, the footage speed is controlled according to the geological conditions: when drilling from a hard stratum to a soft stratum, the drilling speed can be appropriately accelerated; when the soft stratum becomes a hard stratum, the drilling speed should be slowed down; in the stratum that is easy to shrink, the number of hole sweeps should be appropriately increased to prevent shrinkage; for the hard plastic layer, a fast speed drilling is used to improve the drilling efficiency; for the sand layer, a slow speed slow drilling is used and the mud specific gravity and viscosity are appropriately increased. In order to accurately control the hole depth, a calibrated steel wire measuring rope should be prepared, and an automatic depth recorder should be observed to observe and record during construction. The verticality of the drill rod should be checked frequently during the drilling process to ensure that the hole wall is vertical. During the drilling process, the lifting speed of the drill bit in the hole must be controlled to prevent the hole wall from collapsing due to the scouring of the hole wall by the slurry and the negative pressure. During the drilling process, according to the changes in the stratum and hole depth, the drilling parameters should be reasonably selected, and the mud should be adjusted in time to ensure the quality of the hole. When entering the sand layer, the penetration speed should be appropriately slowed down, and the rotation speed should be controlled within 0.5m / min. Increase the viscosity of the mud, reduce the penetration of each drilling round, and ensure the stability of the hole wall. During drilling construction, use a positive shovel to remove the drilling slag in time to ensure that the site is clean and tidy, which is conducive to the next step of construction. After the drilling reaches the required hole depth and stops drilling, pay attention to maintaining the slurry surface elevation in the hole to ensure the stability of the hole wall.

[0083] During the drilling process, the footage of each drilling stroke should be controlled at about 0.5m. Each time the drilling assembly is lifted, qualified mud should be injected into the hole to the hole mouth in time to ensure the stability of the hole wall. During drilling, the footage should not be exceeded to prevent excessive sediment in the hole. After each drilling, the flatness and center point of the drilling rig 1 should be observed when drilling. If there is any deviation, it must be adjusted in time before drilling to prevent the hole from tilting.

[0084] Hole cleaning construction: After the hole is formed, the primary and secondary hole cleaning are carried out to reduce the mud density and remove the sediment at the bottom of the hole;

[0085] Hole cleaning is divided into primary hole cleaning and secondary hole cleaning. Both impact drilling and rotary drilling use positive circulation for hole cleaning.

[0086] The first hole cleaning is carried out after the hole is completed: add clean water in the hole to reduce the mud density to about 1.18, the viscosity is about 20s~22s, the sand content is 4%~6%, and the sediment at the bottom of the hole is less than 50mm. After the first hole cleaning, the exploration cage and the steel cage in the pile are immediately lowered to prevent the collapse or shrinkage of the hole due to too long time. The second hole cleaning is a process carried out after the steel cage in the pile is placed and before the concrete is poured. Its purpose is to clean the new sediment formed at the bottom of the hole during the placement of the steel bars. It is planned to use the positive circulation method of the mud pump to clean the hole. Before pouring concrete, the mud density should be 1.15, the sand content should be less than 2%, the viscosity should be 20~22s, and there should be no sediment at the bottom of the hole.

[0087] After the secondary hole cleaning is qualified, the concrete pouring should be carried out as soon as possible. The stagnation time should not be too long. If the stagnation time is too long, the solid particles in the mud will adhere to the hole wall to form a thick mud skin due to the certain permeability of the hole wall soil layer. The mud skin is sandwiched between the concrete and the soil wall during the concrete pouring, which has a lubricating effect and reduces the friction between the concrete and the soil wall. In addition, the hole wall is immersed in the mud for a long time, and some properties of the soil will also change. Some soil layers may expand and the strength will decrease, which will also affect the bearing capacity of the pile. Therefore, during construction, the time from hole formation to concrete pouring is shortened, and concrete is poured as soon as possible within 30 minutes after the hole cleaning is qualified; it is required that the mud index and the bottom sediment of the hole meet the requirements during the first hole cleaning before the steel cage can be lowered. The secondary hole cleaning uses a cyclone sand remover to separate the sand. At the same time, the guide tube mouth is about 10cm away from the bottom of the hole. Intermittent shaking of the guide tube can move the guide tube to the bottom of the hole for hole cleaning until the main performance indicators of the mud meet the requirements, and the bottom sediment of the hole can also be removed smoothly.

[0088] Lowering the steel cage: The steel cage is designed to be circular and is lowered in sections using a crane. The guide tubes are placed and concrete is poured.

[0089] The steel cage is designed to be circular and is manufactured in a steel processing plant. During the manufacturing process, the main reinforcement frame structure and the outer spiral must be welded and fixed with a 50mm diameter and 1.2mm thick acoustic detection tube through a "U"-shaped clamp. The steel cage is transported to the construction site in sections and is extended and lowered in sections by a truck crane. Before the steel cage is hoisted, a probe cage must be lowered. The diameter of the probe cage is 120cm. After the probe cage is successfully lowered, the steel cage is lowered immediately. Concealed engineering acceptance must also be carried out. After passing the acceptance, the steel cage should be lowered and concrete poured immediately.

[0090] On the other hand, the present application also proposes a drilling device for cast-in-place pile construction, which is applied to the aforementioned drilling method, and the drilling device comprises:

[0091] A drilling rig 1, a drive shaft 2 and a drilling assembly, wherein the drilling assembly is connected to the drilling rig 1 via the drive shaft 2, and the drilling rig 1 can drive the drilling assembly to rotate and / or rise and fall;

[0092] The drilling assembly includes an anti-shrinkage unit 3 and a drilling unit 8, wherein the anti-shrinkage unit 3 is used to prevent the hole from shrinking, and the drilling unit 8 can be fed downward to drill;

[0093] The anti-shrinkage unit 3 is installed above the drilling unit 8, and the anti-shrinkage unit 3 is connected to the driving shaft 2;

[0094] The anti-retraction unit 3 has a tendency to actively expand outward in the radial direction of the drive shaft 2 and / or a tendency to spontaneously expand outward in the radial direction of the drive shaft 2 .

[0095] According to the above technical solution, the drilling rig 1 drives the drilling assembly to rotate and lift through the driving shaft 2. It should be noted that the drilling rig 1 drives the drilling assembly to rotate and lift through the driving shaft 2, which is a prior art and will not be elaborated on here. At the same time, in the above-mentioned mud preparation and circulation steps, grouting can directly act on the anti-shrinkage unit 3 and the drilling unit 8 to prevent mud residue from affecting the expansion and contraction of the anti-shrinkage unit 3. At the same time, grouting can also cool the drilling unit 8 and extend the service life of the drilling unit 8.

[0096] The drilling assembly is mainly composed of an anti-shrinkage unit 3 and a drilling unit 8; during the drilling process, the drilling unit 8 is responsible for feeding downward to perform the actual drilling operation; at the same time, the anti-shrinkage unit 3 is installed above the drilling unit 8 and is connected to the drive shaft 2. This design enables the anti-shrinkage unit 3 to actively and / or spontaneously expand outward along the radial direction of the drive shaft 2 during drilling, thereby closely fitting the inner wall of the hole and effectively preventing the occurrence of shrinkage holes. When the drilling operation is completed, the anti-shrinkage unit 3 can be retracted back to its original position, facilitating the lifting and moving of the device, and preparing for the next stage of construction. The present application not only improves the efficiency and quality of the drilling operation, but also effectively solves the shrinkage hole problem that is prone to occur in traditional drilling construction.

[0097] As a preferred embodiment, the anti-shrinkage unit 3 includes an active expansion structure 4, which includes a mounting seat 41, an expansion block 42, a telescopic rod 43 and a driving structure 6. There are multiple expansion blocks 42 and telescopic rods 43, and each expansion block 42 is distributed around the mounting seat 41. The expansion blocks 42 are enclosed together to form an annular structure; a connecting piece is provided between adjacent expansion blocks 42, and each telescopic rod 43 is located between the connecting piece and the mounting seat 41 and connected to the connecting piece;

[0098] The driving structure 6 is mounted on the mounting seat 41 , and is used to drive the expansion block 42 to expand outward or contract inward.

[0099] Furthermore, the driving structure 6 includes a bracket portion 61 and a driving portion 62, the driving portion 62 is used to drive the bracket portion 61 to rotate; the bracket portion 61 includes a central axis 611, a first bracket 612 and a second bracket 613, the first bracket 612 and the second bracket 613 are installed on the central axis 611, and the first bracket 612 and the second bracket 613 are used to connect with corresponding connecting parts.

[0100] According to the above technical solution, there are multiple expansion blocks 42, which are evenly distributed around the mounting seat 41 and together form an annular structure. Each expansion block 42 is connected to the telescopic rod 43 through a connecting piece, and the other end of the telescopic rod 43 is fixed on the mounting seat 41. This design enables the expansion block 42 to expand or contract along the radial direction of the mounting seat 41 under the action of the driving structure 6; specifically, when the drilling operation is started, the driving part 62 starts to work, and the driving part 62 drives the central axis 611 to rotate to a certain extent (such as clockwise rotation), thereby driving the first bracket 612 and the second bracket 613 to change their positions and angles, and expand outward. When the first bracket 612 and the second bracket 613 expand outward, they push the corresponding connecting piece connected thereto to move outward, and the telescopic rod 43 extends accordingly. While the connecting piece moves outward, it drives the expansion block 42 to expand outward. At the same time, the connecting piece and telescopic rod 43 between adjacent expansion blocks 42 also play the role of transmitting force and maintaining structural stability. In this way, the entire annular structure can be closely close to the inner wall of the hole, so as to effectively prevent the occurrence of shrinkage. On the contrary, when the shrinkage-proof unit 3 needs to be retracted, the driving part 62 drives the central axis 611 to rotate in the opposite direction to a certain extent (such as counterclockwise rotation), and the first bracket 612 and the second bracket 613 shrink inward, driving the connecting piece and the expansion block 42 to shrink inward. At this time, the telescopic rod 43 will also be shortened accordingly to adapt to the shrinking action of the expansion block 42. In this way, the shrinkage-proof unit 3 can be easily retracted back to its original position after the drilling operation is completed, which is convenient for the lifting and moving of the device. The active expansion structure 4 of the shrinkage-proof unit 3 achieves close fit and effective support to the inner wall of the hole through the synergistic effect of the driving structure 6, the expansion block 42, the telescopic rod 43 and the connecting piece, thereby greatly improving the stability and quality of the drilling operation and facilitating the subsequent placement of the steel cage.

[0101] As a preferred embodiment, the connecting member includes a connecting block 71 and two connecting rods 72, the two connecting rods 72 are respectively hinged to the two ends of the connecting block 71, and the other ends of the two connecting rods 72 are hinged to the corresponding expansion blocks 42. According to the above technical solution, the connecting member realizes a stable connection between the expansion blocks 42 through the connecting block 71 and the two connecting rods 72, the two connecting rods 72 are respectively hinged to the two ends of the connecting block 71, and then hinged to the corresponding expansion block 42, forming a flexible connection structure, and in the process of expansion or contraction, the connecting rods 72 can adaptively adjust the angle with the movement of the expansion block 42 to achieve the purpose of outward expansion or inward contraction.

[0102] As a preferred embodiment, the first bracket 612 includes a first link 6121, a second link 6122, a third link 6123, a fourth link 6124 and a fifth link 6125, the second link 6122 and the third link 6123 are hinged at both ends of the first link 6121, the fourth link 6124 is fixed to the first link 6121, and the fourth link 6124 is hinged to the fifth link 6125;

[0103] The second bracket 613 includes a sixth link 6131, a seventh link 6132, an eighth link 6133, a ninth link 6134 and a tenth link 6135. The seventh link 6132 and the eighth link 6133 are hinged to the sixth link 6131. ​​One end of the ninth link 6134 is fixed to the sixth link 6131, and the other end is hinged to the tenth link 6135.

[0104] The middle parts of the first connecting rod 6121 and the fourth connecting rod 6124 are fixed on the central shaft 611; the number of connecting members is six, namely connecting member 1 711, connecting member 2 712, connecting member 3 713, connecting member 4 714, connecting member 5 715 and connecting member 6 716;

[0105] Among them, the second connecting rod 6122 is hinged to the connecting member 1 711, the third connecting rod 6123 is hinged to the connecting member 4 714, the fifth connecting rod 6125 is hinged to the connecting member 2 712; the eighth connecting rod 6133 is hinged to the connecting member 3 713, the seventh connecting rod 6132 is hinged to the connecting member 6 716, and the tenth connecting rod 6135 is hinged to the connecting member 5 715.

[0106] According to the above technical solution, the connecting rod mechanism realizes the effective driving of each expansion block 42. First, the first bracket 612 and the second bracket 613 are respectively connected to the central axis 611 through their own connecting rods to form a stable support structure. In the first bracket 612, the second connecting rod 6122 and the third connecting rod 6123 are hinged at both ends of the first connecting rod 6121, and the fourth connecting rod 6124 is fixed to the first connecting rod 6121 and hinged to the fifth connecting rod 6125.

[0107] When the central axis 611 is driven, it drives the first link 6121 and the fourth link 6124 to rotate around the central axis 611. Since the fourth link 6124 is hinged to the fifth link 6125, the fifth link 6125 will move accordingly with the rotation of the fourth link 6124. At the same time, the second link 6122 and the third link 6123 are hinged at both ends of the first link 6121 and will also swing with the rotation of the first link 6121.

[0108] In the second bracket 613, the seventh link 6132 and the eighth link 6133 are hinged to the sixth link 6131, and one end of the ninth link 6134 is fixed to the sixth link 6131, and the other end is hinged to the tenth link 6135. When the sixth link 6131 receives the driving force from the central shaft 611, it will drive the seventh link 6132 and the eighth link 6133 to swing accordingly, and the ninth link 6134 and the tenth link 6135 will also move relative to each other through the hinge point. The driving force is transmitted to each correspondingly arranged expansion block 42. Specifically, the second link 6122 is hinged to a certain expansion block 42 through the connecting member 1 711, and the third link 6123 is hinged to another expansion block 42 through the connecting member 4 714. When the connecting rods of the first bracket 612 move, these connecting members will drive the expansion block 42 to perform corresponding expansion or contraction movements. Similarly, the sixth connecting rod 6131 is hinged to the other two expansion blocks 42 through the sixth connecting member 716 and the third connecting member 713, the eighth connecting rod 6133 is hinged to the third connecting member 713, the seventh connecting rod 6132 is hinged to another expansion block 42 through the sixth connecting member 716, and the tenth connecting rod 6135 is hinged to the expansion block 42 through the fifth connecting member 715. When the connecting rod of the second bracket 613 moves, these connecting members will also drive the corresponding expansion block 42 to expand or contract. In this way, the connecting rod mechanism can accurately control the movement trajectory and speed of each expansion block 42, thereby achieving close fit and effective support to the inner wall of the hole to avoid shrinkage.

[0109] The driving part 62 is a driving member 1 or a driving member 2;

[0110] As an exemplary embodiment, scheme one: driving member one includes a first driving motor 621, a worm 622 and a worm wheel 623, the worm wheel 623 is coaxially connected to the central shaft 611, the worm 622 is meshed with the worm wheel 623, and the driving motor is connected to the worm 622 to drive the worm 622 to rotate; according to the above technical scheme, in scheme one, the driving part 62 adopts a driving member one, and its core components include a first driving motor 621, a worm 622 and a worm wheel 623. The worm wheel 623 is coaxially connected to the central shaft 611 to form a fixed transmission relationship. The worm 622 is meshed with the worm wheel 623, and the torque transmission and the speed reduction are realized through the meshing transmission of the worm wheel 623 and the worm 622. When the first driving motor 621 is started, it will output rotational power and be connected to the worm 622 through a transmission device such as a coupling (not shown), thereby driving the worm 622 to rotate. Since the worm 622 is meshed with the worm wheel 623, the rotation of the worm 622 will drive the worm wheel 623 to rotate synchronously. Since the worm wheel 623 is coaxially connected to the central shaft 611, the rotation of the worm wheel 623 will be directly transmitted to the central shaft 611, causing the central shaft 611 to start rotating.

[0111] The rotation of the central shaft 611 will further drive the first bracket 612 and the second bracket 613 connected thereto to perform complex relative movements, and then drive each expansion block 42 to perform corresponding expansion or contraction movements through the connecting member. This transmission method has the advantages of compact structure, large transmission ratio, and strong load-bearing capacity, and is suitable for occasions where precise control of rotation angle and torque is required.

[0112] In a possible implementation, the second driving member includes a second driving motor, and the second driving motor is coaxially connected to the central axis 611 .

[0113] Working principle of the second driving member: In the second solution, the driving part 62 adopts the second driving member, and its core component is the second driving motor. Different from the first solution, the second driving motor is directly connected to the central shaft 611 coaxially, forming a more direct transmission relationship.

[0114] When the second drive motor is started, it will output rotational power and directly transmit it to the central shaft 611, causing the central shaft 611 to start rotating. Since the second drive motor is coaxially connected to the central shaft 611, the rotation speed of the motor is consistent with the rotation speed of the central shaft 611, and there is no need to reduce or increase the speed through an additional transmission device. The rotation of the central shaft 611 will also drive the first bracket 612 and the second bracket 613 to move relative to each other, and drive each expansion block 42 to perform corresponding expansion or contraction actions through the connecting piece. This transmission method has the advantages of simple structure and high transmission efficiency, and is suitable for occasions requiring fast response and high speed.

[0115] It should be noted that the first drive motor 621 and the second drive motor are forward and reverse motors.

[0116] As a preferred embodiment, the anti-shrinkage unit 3 includes a driven expansion structure 5, and the number of the driven expansion structures 5 is multiple, and each driven expansion structure 5 is respectively installed on one of the expansion blocks 42; each driven expansion structure 5 can expand outward or shrink inward;

[0117] When the driving shaft 2 rotates, the driven expansion structure 5 is in an outward expansion state, and when the driving shaft 2 is stationary, the driven expansion structure 5 is in an inward contraction state.

[0118] According to the above technical solution, when the drive shaft 2 starts to rotate, the driven expansion structure 5 is installed on the expansion block 42, so it will perform corresponding expansion actions as the expansion block 42 moves. In the process of the driven expansion structure 5 expanding outward, they are closely attached to the inner wall of the hole, contact and rub the inner wall of the hole, further enhancing the density of the inner wall of the hole to improve stability, and can effectively prevent the hole from shrinking during the drilling process, thereby ensuring the quality and stability of the drilling; when the drive shaft 2 is stationary, the entire transmission system also stops working. At this time, the driven expansion structure 5 will gradually return to the state of contraction inward due to the loss of the external driving force. This design allows the device to reduce the occupied space when it is not working. When the driven expansion structure 5 is subjected to the external driving force, it can flexibly adjust the angle and position to adapt to the size and shape of different holes. It can be used in various drilling operations and has wide applicability and practicality.

[0119] As a preferred embodiment, the driven extension structure 5 includes a slide bar 51, a mounting bar 52, a first connecting bar 53, a second connecting bar 54 and a third connecting bar 55, two ends of the first connecting bar 53 are respectively hinged to one end of the slide bar 51 and one end of the mounting bar 52, two ends of the second connecting bar 54 are respectively hinged to the other end of the slide bar 51 and the other end of the mounting bar 52, and the first connecting bar 53 and the second connecting bar 54 are parallel to each other;

[0120] A slider 56 and an elastic member 57 are sleeved on the slide rod 51. The elastic member 57 is used to drive the slider 56 to move downward. One end of the third connecting strip 55 is hinged to the slider 56, and the other end of the third connecting strip 55 is hinged to the middle part of the first connecting strip 53. An extrusion column 58 is connected to the mounting strip 52, and the extrusion column 58 is used to squeeze the inner wall of the hole.

[0121] According to the above technical solution, when the drive shaft 2 starts to rotate, it drives the driven expansion structure 5 to rotate. During the rotation process, an outward centrifugal force is generated, and the centrifugal force counteracts the pulling force of the elastic member 57. When rotating at high speed, the centrifugal force is greater than the pulling force of the elastic member 57, thereby driving the first connecting bar 53 and the second connecting bar 54 hinged thereto to change their positions. At this time, the mounting bar 52 expands outward, and the first connecting bar 53 and the second connecting bar 54 are connected to the mounting bar 52 through the slide bar 51, ensuring the stability of the mounting bar 52 during the outward expansion process. As the mounting bar 52 expands outward, the extrusion column 58 connected thereto also moves outward, and the extrusion column 58 enables it to be in close contact with the inner wall of the hole, and increases the density of the inner wall of the hole through friction, thereby improving the stability of the hole. This close fit and friction effectively prevent the shrinkage of the hole during the drilling process. When the drive shaft 2 stops rotating, the centrifugal force disappears. At this time, the pulling force of the elastic member 57 begins to take effect, driving the mounting strip 52 and the extrusion column 58 to retract inward. This retraction action not only helps to reduce the space occupied by the device when not in operation, but also ensures that each component can be restored to its original state when used next time, making it easy to pull out of the hole, thus having wide applicability and practicality.

[0122] As a preferred embodiment, the drilling unit 8 includes a drill barrel 81 and a drill cover 82. The drill cover 82 is installed at the bottom of the drill barrel 81 in an openable manner, and a notch 821 is provided on the drill cover 82. During rotary drilling, mud residue can enter the drill barrel 81 through the notch 821. When the inside of the drill barrel 81 reaches saturation, the drill barrel 81 is lifted upward, the drill cover 82 is opened, the mud residue in the drill barrel 81 is discharged from the drill barrel 81, and then the drill cover 82 is closed, and the drill barrel 81 is lowered into the hole to continue rotary drilling, and this is repeated.

[0123] The drilling unit 8 of this embodiment is designed to cleverly combine the functions of the drill barrel 81 and the drill cover 82 to achieve efficient and stable drilling operations. During the rotary drilling and feeding stage, the drill barrel 81 is slowly lowered into the hole to be drilled. At this time, the drill cover 82 remains closed to ensure the sealing of the inside of the drill barrel 81. As the drill barrel 81 rotates and feeds, the cutting edge at its bottom begins to contact the inner wall of the hole and cuts the soil or rock. Since the drill cover 82 is provided with a notch 821, these mud residues and debris can smoothly enter the inside of the drill barrel 81 through the notch 821. As the rotary drilling operation continues, the mud residue inside the drill barrel 81 gradually accumulates until it reaches a saturated state. At this time, in order to continue the operation and avoid clogging of the drill barrel 81, it is necessary to suspend the rotary drilling and lift the drill barrel 81 upward. In the process of lifting the drill barrel 81, the drill cover 82 is opened, so that the mud residue inside the drill barrel 81 is smoothly discharged; this step is usually completed by a specific opening mechanism or manual operation. After the mud is discharged, the drill cover 82 is quickly closed to ensure the sealing of the inside of the drill barrel 81 during the subsequent lowering process. Subsequently, the drill barrel 81 is lowered into the hole again, and the rotary drilling operation is continued. During this process, the drilling unit 8 repeats the actions of rotary drilling, lifting, slag discharge and lowering until the predetermined drilling depth is reached. Through this working mechanism of the drilling unit 8, the cut mud can be efficiently discharged from the drill barrel 81. The opening and closing design of the drill cover 82 enables the drill barrel 81 to remain internally closed during the lifting and lowering process, preventing the scattering of mud and debris, thereby further improving the operating efficiency and drilling quality; this application has high practical application value.

[0124] The above embodiments are only preferred embodiments for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present application is within the protection scope of the present application.

Claims

1. A drilling device for cast-in-place pile construction, characterized in that: The device comprises: A drilling rig, a drive shaft and a drilling assembly, wherein the drilling assembly is connected to the drilling rig via the drive shaft, and the drilling rig can drive the drilling assembly to rotate and / or rise and fall; The drilling assembly includes an anti-shrinkage unit and a drilling unit, wherein the anti-shrinkage unit is used to prevent the hole from shrinking and the drilling unit can be fed downward to drill the hole; The anti-shrinkage unit is installed above the drilling unit, and the anti-shrinkage unit is connected to the driving shaft; The anti-shrinkage unit has a tendency to actively expand outward along the radial direction of the drive shaft; The anti-shrinkage unit includes an active expansion structure, which includes a mounting seat, an expansion block, a telescopic rod and a driving structure. There are multiple expansion blocks and telescopic rods, and each expansion block is distributed around the mounting seat, and each expansion block is enclosed together to form an annular structure; A connecting piece is provided between adjacent expansion blocks, and each telescopic rod is located between the connecting piece and the mounting seat and connected to the connecting piece; the driving structure is installed on the mounting seat, and is used to drive the expansion block to expand outward or contract inward; The anti-shrinkage unit comprises a driven expansion structure, the number of the driven expansion structures is multiple, and each of the driven expansion structures is correspondingly mounted on one of the expansion blocks; Each of the driven expansion structures can expand outwards or contract inwards; When the drive shaft rotates, the driven expansion structure is in an outward expansion state; when the drive shaft is stationary, the driven expansion structure is in an inward contraction state; The driven expansion structure comprises a sliding rod, a mounting bar, a first connecting bar, a second connecting bar and a third connecting bar, the two ends of the first connecting bar are respectively hinged to one end of the sliding rod and one end of the mounting bar, the two ends of the second connecting bar are respectively hinged to the other end of the sliding rod and the other end of the mounting bar, and the first connecting bar and the second connecting bar are parallel to each other; The mounting bar is connected with an extrusion column, and the extrusion column is used to extrude the inner wall of the hole; The driving structure comprises a support part and a driving part, and the driving part is used to drive the support part to rotate; The bracket portion includes a central axis, a first bracket and a second bracket, wherein the first bracket and the second bracket are mounted on the central axis, and the first bracket and the second bracket are used to be connected to the corresponding connecting member.

2. The device according to claim 1, characterized in that: The connecting member comprises a connecting block and two connecting rods, the two connecting rods are respectively hinged to two ends of the connecting block, and the other ends of the two connecting rods are hinged to the corresponding expansion blocks.

3. The device according to claim 2, characterized in that: The first bracket includes a first link, a second link, a third link, a fourth link and a fifth link, the second link and the third link are hinged at two ends of the first link, the fourth link is fixed to the first link, and the fourth link is hinged to the fifth link; The second bracket comprises a sixth connecting rod, a seventh connecting rod, an eighth connecting rod, a ninth connecting rod and a tenth connecting rod, wherein the seventh connecting rod and the eighth connecting rod are hinged to the sixth connecting rod, and one end of the ninth connecting rod is fixed to the sixth connecting rod, and the other end is hinged to the tenth connecting rod; The middle parts of the first connecting rod and the fourth connecting rod are fixed on the central shaft; The number of the connecting pieces is six, namely, connecting piece 1, connecting piece 2, connecting piece 3, connecting piece 4, connecting piece 5 and connecting piece 6; Among them, the second connecting rod is hinged to the connecting member 1, the third connecting rod is hinged to the connecting member 4, and the fifth connecting rod is hinged to the connecting member 2; the eighth connecting rod is hinged to the connecting member 3, the seventh connecting rod is hinged to the connecting member 6, and the tenth connecting rod is hinged to the connecting member 5.

4. The device according to claim 1, characterized in that: The driving part is driving member 1 or driving member 2; The first driving member includes a first driving motor, a worm and a worm wheel, the worm wheel is coaxially connected to the central axis, the worm is meshed with the worm wheel, and the first driving motor is connected to the worm to drive the worm to rotate; The second driving member includes a second driving motor, and the second driving motor is coaxially connected to the central axis.

5. The device according to claim 1, characterized in that: The slide bar is sleeved with a slider and an elastic member, the elastic member is used to drive the slider to move downward, one end of the third connecting strip is hinged to the slider, and the other end of the third connecting strip is hinged to the middle of the first connecting strip.

6. The device according to claim 1, characterized in that: The drilling unit comprises a drill tube and a drill cover. The drill cover is installed at the bottom of the drill tube in an openable and closable manner, and a notch is arranged on the drill cover.

7. A drilling method for cast-in-place pile construction, characterized in that: The following steps are involved: Casing installation: Drill a pre-set hole with the same diameter as the casing, and accurately lower and secure the casing; Mud preparation and circulation: Prepare mud with specific gravity, viscosity and sand content according to the formation conditions, and maintain the stability of the mud in the hole through positive circulation and / or reverse circulation; Hole forming construction: using the device as described in any one of claims 1 to 6 to perform drilling operations, and adjusting drilling parameters and mud properties to ensure hole forming quality and hole wall stability; Hole cleaning construction: After the hole is formed, the primary and secondary hole cleaning are carried out to reduce the mud density and remove the sediment at the bottom of the hole; Lowering the steel cage: The steel cage is designed to be circular and is lowered in sections using a crane. The guide tubes are placed and concrete is poured.

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