YKP construction method for cast-in-place pile and cast-in-place pile manufactured thereby

Abstract

This invention discloses a YKP method for constructing cast-in-place piles and the resulting cast-in-place piles, belonging to the field of pile foundation technology. The YKP method for constructing cast-in-place piles involves statically pressing an outer casing into the soil to form a pile hole. An inner sleeve is then used to press extruded concrete from the outer casing into the soil to form a concrete enlargement. Simultaneously, reinforcing members are pressed into the enlargement to form a rigid concrete enlarged head. A reinforcing cage assembly is then placed inside the outer casing, and concrete is poured. After the concrete has initially set, the outer casing is removed, and grouting pipes are used to fill the side gaps with concrete, forming a cement-soil outer ring. This method solves the problems of high noise and severe environmental pollution associated with existing construction methods. There is no collapse, sediment, or necking of the borehole wall, ensuring reliable pile quality. The resulting cast-in-place pile has a cement-soil outer ring on the outside, significantly increasing the frictional resistance between the pile and the surrounding soil. The rigid concrete enlarged head also effectively improves the bearing capacity of the cast-in-place pile.

Description

Technical Field

[0001] This invention relates to a cast-in-place pile, and more specifically, to a YKP method for constructing cast-in-place piles and the cast-in-place piles manufactured therefrom. Background Technology

[0002] Cast-in-place piles are piles made by forming pile holes in the foundation soil through mechanical drilling, steel pipe extrusion, or manual excavation on the engineering site, placing a steel cage inside, and pouring concrete. Depending on the hole-forming method, cast-in-place piles can be divided into driven cast-in-place piles, drilled cast-in-place piles, excavated cast-in-place piles, rammed and expanded cast-in-place piles, and long spiral drilled and pressurized cast-in-place piles.

[0003] (1) Driven cast-in-place piles are one of the many types of pile foundations in civil engineering. They are constructed by using a steel pipe (i.e., a casing) that is adapted to the design dimensions of the pile. After the pile tip is fitted onto the end, the pipe is driven into the soil. A steel reinforcement cage is then suspended inside the casing. Concrete is poured while the casing is vibrated or hammered for extraction. The vibration during extraction compacts the concrete to form the required cast-in-place pile. The main disadvantages are that vibration-driven pile construction is noisy and causes serious environmental pollution. Secondly, the vibration extraction process excites the surrounding soil, causing soil damage and lateral compression, which can easily lead to pile necking.

[0004] (2) The construction of bored piles can be divided into two types: mud wall construction method and full casing construction method, depending on the different wall formations selected.

[0005] Mud wall construction methods include percussion drilling, percussion gripping drilling, and rotary drilling. The process is as follows: site leveling → mud preparation → casing installation → working platform setup → drilling rig installation and positioning → drilling → hole cleaning and quality inspection → lowering the reinforcing cage → underwater concrete pouring → casing removal → quality inspection. The main disadvantages are: the presence of mud, causing environmental pollution; and the lateral mud skin produced by the mud, reducing lateral friction. Additionally, because mud is used at the bottom of the hole, sediment often accumulates, which significantly reduces the pile's bearing capacity.

[0006] The general construction process of the full casing method is as follows: leveling the site, laying the working platform, installing the drilling rig, pressing the casing, drilling the hole, placing the reinforcing cage, placing the guide pipe, pouring concrete, pulling out the casing, and checking the pile quality. The main disadvantages are: it requires a full-rotation drilling rig for casing pressing, and subsequently requires a grab bucket to remove the excavated soil from the hole, resulting in low drilling efficiency. Furthermore, the excavated soil needs to be transported off-site, increasing costs.

[0007] (3) Manually excavated cast-in-place piles are formed by manually excavating holes, using appropriate lifting and earth-moving tools, and then lowering a steel cage and pouring concrete to form the pile after reaching the designed depth. The main disadvantages are that the manual excavation method is dangerous and the personal safety of workers cannot be guaranteed. In addition, the use of brick or reinforced concrete retaining rings and walls results in a large waste of materials.

[0008] (4) Rammed and enlarged cast-in-place piles are an improvement on the mechanical equipment and construction methods of hammer-driven cast-in-place piles. An internal ramming pipe is added, and the cast-in-place concrete at the pile end is enlarged into a large-head shape using a ramming and enlargement method according to a specific construction process. The main disadvantages are: the use of a ramming and enlargement hammer results in high construction noise and serious environmental pollution. Furthermore, because the enlarged head lacks internal reinforcing steel bars, it cannot form an effective rigid enlarged body, and the enlarged head cannot fully realize its potential.

[0009] (5) Long spiral drilled cast-in-place piles utilize a long spiral drilling rig to drill to the design elevation. After drilling stops, while the drill is being lifted, super-fluid concrete is injected through a concrete hole located on the inner pipe drill bit. After injection to the design pile top elevation, the drill rod is removed and the reinforcing cage is pressed into the pile body. The main disadvantages are: the long spiral drills drill and inject concrete simultaneously, and the soil on the side of the hole can easily infiltrate into the concrete, posing a potential risk to the quality of the pile. In addition, the reinforcing cage is pressed in before the initial setting of the concrete after pouring, and due to the obstruction of the concrete, the reinforcing cage is not easy to insert into place. It is also not suitable for engineering piles with very deep pile lengths.

[0010] It is evident that existing cast-in-place piles suffer from the following major problems: ① High construction noise and serious noise pollution; ② Mud pollution, causing serious environmental pollution; ③ Difficulty in controlling sediment, which can easily lead to a reduction in the bearing capacity of the pile; ④ Lack of an effective rigid enlarged head, and the concrete enlarged head can only play a limited role; ⑤ Difficulty in controlling the quality of the pile body, posing potential quality risks. Summary of the Invention

[0011] 1. The technical problem that the invention aims to solve

[0012] The purpose of this invention is to overcome the aforementioned problems of existing cast-in-place piles and to provide a YKP method for constructing cast-in-place piles and the resulting piles. Using the technical solution of this invention, an outer casing is pressed into the soil using a static pressure pile driver or a non-resonant hydraulic vibratory hammer to form a pile hole. An inner sleeve is then used to press extrusion concrete from the outer casing into the soil to form a concrete enlargement. Simultaneously, a reinforcing member is pressed into the enlargement to form a rigid concrete enlargement head. A reinforcing cage assembly is then placed inside the outer casing, and concrete is poured. After the concrete has initially set, the outer casing is removed, and grouting pipes are used to fill the side gaps with concrete, forming a cement-soil outer ring. This method solves the problems of high noise and severe environmental pollution associated with existing construction methods. Furthermore, by directly pressing the outer casing into the hole, there is no collapse, sediment, or necking of the hole wall, ensuring reliable pile quality. The resulting cast-in-place pile has a cement-soil outer ring on the outside, which significantly increases the frictional resistance between the pile and the surrounding soil, and the rigid concrete enlargement head effectively improves the bearing capacity of the cast-in-place pile.

[0013] 2. Technical Solution

[0014] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0015] This invention discloses a YKP method for constructing cast-in-place piles, comprising auxiliary construction tools and precast pile reinforcement components. The auxiliary construction tools include an outer casing, a discardable pile tip, and an inner sleeve. The discardable pile tip is inserted and installed at the lower end of the outer casing. The outer wall shape and size of the inner sleeve are adapted to the inner wall shape and size of the outer casing, and the lower end of the inner sleeve is closed. The precast pile reinforcement components include an enlarged reinforcement component and a reinforcing cage assembly, wherein the reinforcing cage assembly has a grouting pipe.

[0016] The specific construction method includes the following steps:

[0017] S1. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press the outer casing with the discardable pile tip into the soil to form a pile hole in the soil.

[0018] S2. First, a certain amount of extruded concrete is poured into the outer casing, and then the inner sleeve is inserted into the outer casing.

[0019] S3. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press down the inner sleeve, and press the extruded concrete in the outer casing into the soil to form a concrete enlargement. At this time, the discardable pile tip is separated from the outer casing and left in the concrete enlargement.

[0020] S4. Remove the inner sleeve and place the enlarged body reinforcement into the outer sleeve. Then, use the inner sleeve again to press the enlarged body reinforcement into the concrete enlarged body to form a rigid concrete enlarged head.

[0021] S5. Remove the inner sleeve, place the steel cage assembly into the outer sleeve, and fix the steel cage assembly.

[0022] S6. Pour concrete from bottom to top to the design elevation or above;

[0023] S7. After the concrete has initially set in step S6, the outer casing is pulled out using a static pressure pile driver or a non-resonance hydraulic vibratory hammer. After the outer casing is pulled out, grout is injected into the gaps in the casing through a grouting pipe to fill the gaps with concrete, forming a cement-soil outer ring.

[0024] Furthermore, the outer casing is composed of several casing pipe sections connected together, with adjacent casing pipe sections connected by a casing connection assembly. The discardable pile tip is installed at the lower end of the first casing pipe section. During construction, the first casing pipe section is first pressed into the soil, then the next casing pipe section is lifted and connected to the previous casing pipe section through the casing connection assembly, and the pressing continues until the designed pile top elevation.

[0025] Furthermore, the cylindrical connecting assembly includes a male connector, a male connector gasket, a pin, a female connector, and a female connector gasket. The male connector and the female connector are respectively fixedly installed at the ends of two adjacent sections of the protective cylinder fitting. The male connector can be axially inserted into the female connector. The outer periphery of both the male connector and the female connector is provided with several corresponding connection holes. The male connector gasket is fixed in the corresponding connection hole of the male connector, and the female connector gasket is fixed in the corresponding connection hole of the female connector. After the male connector and the female connector are inserted, the positions of the male connector gasket and the female connector gasket correspond one-to-one, and the pin is correspondingly installed in the pin holes of the male connector gasket and the female connector gasket.

[0026] Furthermore, the discardable pile tip is also equipped with a high-pressure water jet, which is activated to cut and break the soil when encountering hard soil layers to assist in pile driving; the upper part of the discardable pile tip is provided with a mating protrusion, and the lower end of the outer casing is provided with a mating slot corresponding to the aforementioned mating protrusion. The discardable pile tip is installed in the mating slot at the lower end of the outer casing by inserting the mating protrusion, and separates from the outer casing when the discardable pile tip is squeezed by the extruded concrete.

[0027] Furthermore, the outer casing is a double-walled steel casing, including an outer casing tube, an inner casing tube, and a casing interlayer support. The outer casing tube is sleeved and installed on the outside of the inner casing tube, forming a casing interlayer between the outer casing tube and the inner casing tube. The casing interlayer support is provided inside the casing interlayer.

[0028] The inner sleeve is a double-walled steel sleeve, including an outer sleeve tube, an inner sleeve tube, and a sleeve interlayer support. The outer sleeve tube is sleeved and installed on the outside of the inner sleeve tube, forming a sleeve interlayer between the outer sleeve tube and the inner sleeve tube. A sleeve interlayer support is provided inside the sleeve interlayer.

[0029] Both the casing interlayer support and the sleeve interlayer support are support rings spaced apart along the axial direction or honeycomb support plates located within the interlayer.

[0030] Furthermore, the expanding body reinforcement is an expandable rigid component, including an upper pressure plate, a guide column, a movable plate, and support rods. The upper pressure plate is fixed to the upper end of the guide column, the movable plate is slidably sleeved on the guide column, and the support rods are distributed circumferentially with one end rotatably mounted below the upper pressure plate. The other end of the support rod passes through the corresponding through hole on the movable plate. The through holes on the movable plate are distributed circumferentially, and the diameter of the circle containing each through hole is larger than the diameter of the circle containing the rotating end of the support rod, so that when the movable plate and the upper pressure plate are relatively close, each support rod rotates outward and expands. During construction, the movable plate is placed downward into the outer sleeve, and the inner sleeve presses down to push the upper pressure plate, guide column, and support rods downward. The guide column is inserted into the concrete expanding body, so that the movable plate is relatively close to the upper pressure plate, causing each support rod to expand outward while being inserted into the concrete expanding body.

[0031] Furthermore, the steel cage assembly includes a steel cage body, the grouting pipe is fixedly installed on the side wall of the steel cage body, and a PVC hollow pipe is also provided on the inner side of the steel cage body; during construction, the steel cage assembly is hoisted into the outer casing and the steel cage body is fixed with lifting bars, and after pouring concrete, a reinforced concrete hollow cast-in-place pile with a rigid concrete enlarged head is formed.

[0032] Furthermore, the method for manufacturing the steel cage assembly is as follows:

[0033] S0-1, Stirrups are fixed every a meters along the length direction;

[0034] S0-2. Install a PVC hollow pipe in the middle of the stirrup. The PVC hollow pipe is composed of several PVC pipe sections connected together. Adjacent PVC pipe sections are connected by PVC pipe joints.

[0035] S0-3. After installing the stirrups and PVC hollow pipes, weld the main reinforcement bars onto the stirrups. Adjacent main reinforcement bars in the same length direction are connected by sleeves.

[0036] S0-4. After the main reinforcement is welded, the spiral reinforcement is welded and fixed.

[0037] The present invention relates to a cast-in-place pile manufactured using the aforementioned YKP method for cast-in-place pile construction.

[0038] Furthermore, the cast-in-place pile includes a pile body and a rigid concrete enlarged head located at the lower part of the pile body. The rigid concrete enlarged head includes a concrete enlarged body and an enlarged body reinforcement embedded in the concrete enlarged body. The lower part of the rigid concrete enlarged head also has a discardable pile tip. The pile body has a steel cage assembly inside and a cement-soil outer ring outside the pile body.

[0039] 3. Beneficial effects

[0040] Compared with existing known technologies, the technical solution provided by this invention has the following significant advantages:

[0041] (1) The YKP method for constructing cast-in-place piles and the cast-in-place piles manufactured according to the present invention have the following main technical advantages:

[0042] 1-1. The use of static pressure or non-resonance hydraulic vibratory hammer construction methods has solved the problems of high noise and serious environmental pollution;

[0043] 1-2. Because the outer casing is directly pressed into the hole, there is no mud or need for excavation, resulting in high hole formation efficiency and low cost.

[0044] 1-3. By using an outer casing in conjunction with a discardable pile tip for direct drilling, the problem of difficult sediment control is solved, resulting in no sediment.

[0045] 1-4. Because of the adoption of rigid concrete enlarged head technology, the problem of existing cast-in-place piles lacking effective rigid enlarged heads has been solved, greatly improving the bearing capacity of cast-in-place piles;

[0046] 1-5. Because an outer casing is used for pressure conveying, there is no collapse of the borehole wall or necking, which affects the quality. At the same time, after the concrete has initially set, the outer casing is removed and pressure grouting is performed. The resulting cement-soil outer ring greatly increases the frictional resistance between the pile and the soil on the pile side, thereby effectively improving the bearing capacity of the pile.

[0047] (2) The YKP method for constructing cast-in-place piles and the cast-in-place piles manufactured according to the present invention further have the following beneficial effects:

[0048] 2-1. The discardable pile tip serves as a guide during the drilling process, facilitating the insertion of the outer casing into the soil. A high-pressure water jet can be installed on the discardable pile tip to cut and break up the soil when encountering hard soil layers, thus assisting in pile driving and improving drilling efficiency. During the expansion of the concrete body, the discardable pile tip remains at the bottom of the expanded concrete body, further enhancing the pile's bearing capacity. Additionally, the discardable pile tip is installed in a slot at the lower end of the outer casing via a mating protrusion. When the discardable pile tip is compressed by the expanded concrete, it separates from the outer casing, resulting in a simple structural design and convenient construction.

[0049] 2-2. The outer casing is composed of several casing pipe sections connected together. Adjacent casing pipe sections are connected by a casing connection assembly, which facilitates the control of the pile hole depth according to the designed pile top elevation. Furthermore, the casing connection assembly adopts a male-female plug-in joint design and uses pins for locking connection. The structure is simple, the connection is convenient, and the connection is firm and reliable.

[0050] 2-3. Both the outer casing and the inner sleeve adopt a double-wall structure. The interlayer between the outer and inner wall tubes is reinforced with interlayer supports. The interlayer supports can be support rings spaced apart along the axial direction or honeycomb support plates located in the interlayer, which greatly enhances the structural strength of the outer casing and the inner sleeve and enables them to withstand greater pressure.

[0051] 2-4. The expansion body reinforcement is an expandable rigid component, mainly composed of an upper pressure plate, guide column, movable plate, and support rod. During construction, the movable plate is placed downwards into the outer casing, and the inner sleeve presses down to push the upper pressure plate, guide column, and support rod downwards. The guide column is inserted into the concrete expansion body, so that the movable plate is relatively close to the upper pressure plate, causing each support rod to expand outwards while being inserted into the concrete expansion body. After the diameter is expanded, the entire concrete expansion body can be strengthened, improving the structural strength and compressive strength of the rigid concrete expansion head, thereby improving the bearing capacity of the cast-in-place pile.

[0052] 2-5. The steel cage assembly contains PVC hollow pipes, which, after concrete is poured, form a reinforced concrete hollow cast-in-place pile with a rigid concrete enlarged head. This reduces the amount of concrete used and lowers the production cost while ensuring the strength of the cast-in-place pile.

[0053] (3) The YKP method of the present invention for cast-in-place piles improves construction efficiency by 200% to 300% compared with the traditional method, and the construction quality is reliably guaranteed; the bearing capacity of the pile foundation is greatly improved by 10% to 50%; green and pollution-free construction is achieved, and the construction cost is greatly reduced, resulting in significant economic and social benefits. Attached Figure Description

[0054] Figure 1 This is a three-dimensional disassembled structural diagram of the outer casing and the discardable pile tip in this invention;

[0055] Figure 2 for Figure 1 A cross-sectional view of the inner and outer casing and the discarded pile tip in a disassembled state;

[0056] Figure 3 for Figure 2 A magnified schematic diagram of the local structure at point K;

[0057] Figure 4 for Figure 2 A magnified schematic diagram of the local structure at point M;

[0058] Figure 5 This is a schematic diagram of the outer casing structure with raised ribs on the outer wall for easy clamping in this invention;

[0059] Figure 6 This is a cross-sectional view of the inner sleeve in this invention;

[0060] Figure 7 for Figure 6 A magnified schematic diagram of the local structure at point N;

[0061] Figure 8 This is a schematic diagram of a double-walled outer casing using a honeycomb support plate;

[0062] Figure 9 This is a three-dimensional schematic diagram of the inner sleeve being fitted inside the outer protective sleeve in this invention;

[0063] Figure 10 This is a cross-sectional view of the inner sleeve being fitted inside the outer protective sleeve in this invention.

[0064] Figure 11 This is a three-dimensional structural diagram of the enlarged body reinforcement in the contracted state of the present invention;

[0065] Figure 12This is a three-dimensional structural diagram of the expanded body reinforcement in the unfolded state of the present invention;

[0066] Figure 13 This is a three-dimensional structural schematic diagram of the steel cage assembly in this invention;

[0067] Figure 14 This is a schematic diagram of the outer casing pressing step in the YKP method of cast-in-place pile construction method of the present invention;

[0068] Figure 15 This is a schematic diagram of the step of inputting extruded concrete into the outer casing in the YKP method of cast-in-place pile construction method of the present invention;

[0069] Figure 16 This is a schematic diagram of the step of forming a concrete enlarged body by extruding the inner sleeve in the YKP method of cast-in-place pile construction method of the present invention;

[0070] Figure 17 This is a schematic diagram illustrating the steps of inserting the enlarged body reinforcement in the YKP method of cast-in-place pile construction method of the present invention;

[0071] Figure 18 This is a schematic diagram of the step in which the enlarged body reinforcement is pressed into the concrete enlarged body in the YKP method of cast-in-place pile construction method of the present invention.

[0072] Figure 19 This is a schematic diagram illustrating the steps of placing the reinforcing cage assembly in the YKP method of cast-in-place pile construction method of the present invention;

[0073] Figure 20 This is a schematic diagram of the concrete pouring steps in the YKP method for cast-in-place pile construction of the present invention;

[0074] Figure 21 This is a schematic diagram of the step of removing the outer casing in the YKP method of cast-in-place pile construction according to the present invention.

[0075] Explanation of the labels in the diagram:

[0076] 1. Outer casing; 1-1. Casing fittings; 1-1-1. Interlocking slot; 1-1-2. Raised rib; 1-1a. Outer casing tube; 1-1b. Inner casing tube; 1-1c. Casing interlayer support; 2. Disposable pile tip; 2-1. Interlocking protrusion; 3. Casing connection assembly; 3-1. Male connector; 3-2. Male connector gasket; 3-3. Pin fitting; 3-4. Female connector; 3-5. Female connector gasket; 4. Inner sleeve; 4-1. Sleeve fittings; 4-1-1. Sealing plate; 4-1a. Outer wall tube of the sleeve; 4-1b. Inner wall tube of the sleeve; 4-1c. Sleeve interlayer support; 5. Enlarged body reinforcement; 5-1. Upper pressure plate; 5-2. Guide column; 5-3. Movable plate; 5-3-1. Through hole; 5-4. Connecting ring; 5-5. Support rod; 5-5-1. Rotating part; 6. Reinforcing cage assembly; 6-1. Reinforcing cage body; 6-2. Grouting pipe; 6-3. PVC hollow pipe; 7. Extruded concrete; 8. Concrete enlargement body; 9. Side gap concrete. Detailed Implementation

[0077] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings.

[0078] The present invention provides a YKP method for cast-in-place piles, which mainly solves several problems existing in the current cast-in-place pile process: ① high noise and serious environmental pollution; ② mud pollution; ③ difficulty in controlling sediment; ④ lack of effective rigid enlarged head; ⑤ difficulty in controlling pile quality.

[0079] In this invention, "YKP" in YKP method cast-in-place piles has a specific meaning. "Y" means: An outer casing with a pile tip is pressed into the soil using a static pressure method (e.g., a static pressure pile driver or a non-resonant hydraulic vibratory hammer) to form a pile hole. "K" means: A certain amount of concrete is first poured into the outer casing, then the concrete is pressed into the soil through an inner sleeve to form a concrete enlarged body. A reinforcing member is then placed into the enlarged body, and the inner sleeve is used to press the reinforcing member into the concrete of the enlarged body, forming a rigid concrete enlarged head. "P" means: After forming the rigid concrete enlarged head, a steel cage assembly with a grouting pipe is placed in, and then grouting is performed from bottom to top until the top is reached. After initial setting, the outer casing is pulled out using a static pressure pile driver or a non-resonant hydraulic vibratory hammer, and grouting begins to fill the voids left after the outer casing is removed, forming a cement-soil outer layer. This results in a reinforced concrete cast-in-place pile with a rigid enlarged head.

[0080] The specific construction process can be combined with Figures 14 to 21 It includes the following steps:

[0081] S1. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press the outer casing 1 with the discardable pile tip 2 into the soil to form a pile hole in the soil.

[0082] S2. First, a certain amount of extruded concrete 7 is poured into the outer casing 1, and then the inner sleeve 4 is inserted into the outer casing 1.

[0083] S3. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press down the inner sleeve 4, and press the extruded concrete 7 in the outer casing 1 into the soil to form a concrete enlarged body 8. At this time, the discardable pile tip 2 is separated from the outer casing 1 and left in the concrete enlarged body 8.

[0084] S4. Take out the inner sleeve 4 and place the enlarged body reinforcement 5 into the outer sleeve 1. Then, use the inner sleeve 4 again to press the enlarged body reinforcement 5 into the concrete enlarged body 8 to form a rigid concrete enlarged head.

[0085] S5. Remove the inner sleeve 4, place the steel cage assembly 6 into the outer sleeve 1, and fix the steel cage assembly 6.

[0086] S6. Pour concrete from bottom to top to the design elevation or above;

[0087] S7. After the concrete has initially set in step S6, the outer casing 1 is pulled out using a static pressure pile driver or a non-resonance hydraulic vibratory hammer. After pulling out the outer casing 1, grout is injected through the grouting pipe 6-2 to fill the gap concrete 9 in the hole after the outer casing 1 is pulled out, forming a cement-soil outer ring.

[0088] The aforementioned YKP method for cast-in-place piles solves the problems of high noise and severe environmental pollution associated with existing construction methods. Furthermore, by directly pressing an outer casing into the hole, there are no issues such as hole wall collapse, sediment, or necking that affect quality, ensuring reliable pile quality. The resulting cast-in-place pile has a cement-soil outer ring on the outside of the pile body, which greatly increases the frictional resistance between the pile and the soil on the pile side. It also has a rigid concrete enlarged head, which effectively improves the bearing capacity of the cast-in-place pile.

[0089] The present invention will be further described below with reference to embodiments.

[0090] [Example]

[0091] This embodiment relates to a YKP method for constructing cast-in-place piles. The method includes auxiliary construction tools and precast pile reinforcement components. The auxiliary construction tools include an outer casing 1, a discardable pile tip 2, and an inner sleeve 4. The discardable pile tip 2 is inserted into the lower end of the outer casing 1 and can detach from the outer casing 1 when compressed, thus becoming part of the cast-in-place pile. Structural diagrams of the outer casing 1 and the discardable pile tip 2 can be found in [reference needed]. Figures 1 to 4 As shown. The outer wall shape and dimensions of the inner sleeve 4 are adapted to the inner wall shape and dimensions of the outer sleeve 1, allowing the inner sleeve 4 to move axially relative to the outer sleeve 1 after being inserted, while maintaining a small clearance fit between them. The structure of the inner sleeve 4 is as follows. Figure 6 As shown, the lower end of the inner sleeve 4 is closed. The cross-sectional shapes of the outer sleeve 1 and the inner sleeve 4 can be circular or square, depending on the actual needs. The fitting relationship between the outer sleeve 1 and the inner sleeve 4 can be referred to... Figure 9 and Figure 10 As shown. The aforementioned precast pile reinforcement components include an enlarged reinforcement component 5 and a steel cage assembly 6, with a grouting pipe 6-2 on the steel cage assembly 6. Figure 11 and Figure 12 A specific structure of the enlarged body reinforcement 5 is given. Figure 13 A specific structure of a steel cage assembly 6 is presented, and the specific structural principle is explained in detail below.

[0092] This embodiment describes a YKP method for constructing cast-in-place piles. The equipment used mainly includes pile driving equipment, hoisting equipment, grouting equipment, and other auxiliary instruments. The pile driving equipment primarily consists of a static pressure pile driver or a non-resonant hydraulic vibratory hammer; the hoisting equipment mainly includes a crane; the grouting equipment mainly includes concrete pouring equipment and a high-pressure grouting pump; and the auxiliary instruments mainly include a total station, which is used to locate the pile position before construction. The specific construction method includes the following steps:

[0093] S1. Using a static pressure pile driver or a non-resonance hydraulic vibratory hammer, the outer casing 1, equipped with the discardable pile tip 2, is pressed into the soil to form a pile hole; the state of the outer casing 1 pressed into the soil is as follows. Figure 14 As shown, the pile hole is formed by the outer casing 1, and there is no sediment inside the outer casing 1; the outer casing 1 is lifted by a crane, aligned with the pile position, and then pressed in by a static pressure pile driver or a non-resonance hydraulic vibratory hammer until the designed pile top elevation is reached.

[0094] S2. First, a certain amount of extruded concrete 7 is poured into the outer casing 1, and then the inner sleeve 4 is inserted into the outer casing 1 to form... Figure 15 The state shown; the input amount of the extruded concrete 7 is determined according to the volume of the designed enlarged head; the inner sleeve 4 is also lifted by a crane and hoisted into the outer casing 1;

[0095] S3. Using a static pressure pile driver or a non-resonant hydraulic vibratory hammer, the inner sleeve 4 is pressed down, forcing the extruded concrete 7 inside the outer casing 1 into the soil to form a concrete enlargement 8. At this point, the discardable pile tip 2 detaches from the outer casing 1 and remains in the concrete enlargement 8. Figure 16 As shown; in this step, the extruded concrete 7 is subjected to pressure from the sealing plate 4-1-1 at the lower end of the inner sleeve 4, which forces the discarded pile tip 2 to continue to move downward, and the extruded concrete 7 squeezes the soil downward and outward to form the concrete enlarged body 8; when using a static pressure pile driver, the inner sleeve 4 is also pressed downward by clamping pressure; when using a non-resonance hydraulic vibratory hammer, the inner sleeve 4 is also pressed downward by excitation.

[0096] S4. Take out the inner sleeve 4 and place the enlarged body reinforcement 5 into the outer sleeve 1. Then, use the inner sleeve 4 again to press the enlarged body reinforcement 5 into the concrete enlarged body 8 to form a rigid concrete enlarged head. Figure 17 The diagram shows the state of the enlarged body reinforcement 5 inside the outer casing 1. Figure 18 The diagram shows the state in which the inner sleeve 4 presses the enlarged body reinforcement 5 into the concrete enlarged body 8. The enlarged body reinforcement 5 strengthens the concrete enlarged body 8, improving the structural strength and compressive strength of the enlarged head. The enlarged body reinforcement 5 is lifted by a crane and placed into the outer sleeve 1.

[0097] S5. Remove the inner sleeve 4, place the reinforcing cage assembly 6 into the outer casing 1, and fix the reinforcing cage assembly 6; the reinforcing cage assembly 6 is also lifted by a crane, and the elevation of the reinforcing cage is measured using a level, and it is fixed with lifting rods; the state of the reinforcing cage assembly 6 inside the outer casing 1 is as follows. Figure 19 As shown;

[0098] S6. Pour concrete from bottom to top to the design elevation or above. Specifically, it is best to pour concrete to the design elevation and exceed it by 50cm. A crane can be used to insert a guide pipe into the outer casing 1, extending the guide pipe to the bottom of the outer casing 1. Concrete is then poured from bottom to top into the outer casing 1 using concrete pouring equipment. The state after concrete pouring is as follows. Figure 20 As shown;

[0099] S7. After the initial setting of the concrete in step S6, the outer casing 1 is pulled out using a static pressure pile driver or a non-resonant hydraulic vibratory hammer. After pulling out the outer casing 1, grout is injected through the grouting pipe 6-2 to fill the gaps with side concrete 9, forming a cement-soil outer ring layer, ultimately presenting... Figure 21 The outer casing 1 should be pulled out slowly and evenly to avoid excessive speed, which could affect the quality of the concrete. After pulling out the outer casing 1, start the grouting pump and inject grout under high pressure through the grouting pipe 6-2 to form a cement-soil outer ring. This completes the formation of a reinforced concrete pile with a rigid enlarged head.

[0100] like Figures 1 to 3 As shown, in this embodiment, the outer casing 1 is composed of several casing pipe sections 1-1 connected together. Adjacent casing pipe sections 1-1 are connected by a casing connecting assembly 3. The discardable pile tip 2 is installed at the lower end of the first casing pipe section 1-1. During construction, the first casing pipe section 1-1 is first pressed into the soil, then the next casing pipe section 1-1 is lifted and connected to the previous casing pipe section 1-1 through the casing connecting assembly 3. This process continues until the designed pile top elevation is reached, allowing for control of the pile hole depth based on the designed pile top elevation. The casing connecting assembly 3 is a device used to connect hollow pipes. Figure 1and Figure 3 The paper presents a preferred design scheme for the cylindrical connecting assembly 3, which includes a male connector 3-1, a male connector gasket 3-2, a pin 3-3, a female connector 3-4, and a female connector gasket 3-5. The male connector 3-1 and the female connector 3-4 are respectively fixedly installed at the ends of two adjacent sections of the protective casing 1-1. The male connector 3-1 and the female connector 3-4 can be welded to the corresponding protective casing 1-1. Generally, the protective casing 1-1 has three structural forms: the first section, the last section, and the middle section. The first section of the protective casing 1-1 is equipped with a discardable pile tip 2 at the bottom, and the female connector 3-4 can be welded to the upper end. The last section of the protective casing 1-1 only needs to have the male connector 3-1 welded to the lower end. The middle section of the protective casing 1-1 has multiple sections, with the male connector 3-1 welded to the lower end and the female connector 3-4 welded to the upper end. The male connector 3-1 can be axially inserted into the female connector 3-4. Both the male connector 3-1 and the female connector 3-4 have several corresponding connecting holes on their outer circumferences. The male connector gasket 3-2 is fixed in the corresponding connecting hole of the male connector 3-1, and the female connector gasket 3-5 is fixed in the corresponding connecting hole of the female connector 3-4. The male connector gasket 3-2 and the female connector gasket 3-5 can also be welded to their corresponding connecting holes. Pin holes are provided on both the male connector gasket 3-2 and the female connector gasket 3-5. After the male connector 3-1 and the female connector 3-4 are inserted, the positions of the male connector gasket 3-2 and the female connector gasket 3-5 correspond one-to-one, and the pin 3-3 is correspondingly installed in the pin holes of the male connector gasket 3-2 and the female connector gasket 3-5. The pin 3-3 can be inserted into the pin hole by hammering to prevent it from falling out. Alternatively, an internal thread can be provided in the pin hole of the female connector gasket 3-5. The front section of the pin 3-3 has a necked design, and the rear section has an external thread. The threaded connection between the pin 3-3 and the female connector gasket 3-5 prevents loosening. The front section of the pin 3-3 is inserted into the pin hole of the male connector gasket 3-2 to achieve connection. The above-mentioned cylindrical connecting assembly 3 adopts a male-female plug-in design and uses the pin 3-3 for locking connection. The structure is simple, the connection is convenient, and the connection is firm and reliable. Similarly, the inner sleeve 4 can also be formed by connecting several sleeve fittings 4-1. Adjacent sleeve fittings 4-1 can also be connected by the above-mentioned cylindrical connecting assembly 3. The bottom of the first sleeve fitting 4-1 is sealed with a sealing plate 4-1-1. The inner sleeve 4 can be flexibly combined as needed to form the required length of the inner sleeve 4.

[0101] In this embodiment, the discardable pile tip 2 has a conical structure, which serves as a guide during the drilling process, facilitating the insertion of the outer casing 1 into the soil. The discardable pile tip 2 is also equipped with a high-pressure water jet; when encountering hard soil layers, the high-pressure water jet is activated to cut and break up the soil, assisting in pile driving and improving drilling efficiency. The nozzle of the high-pressure water jet is installed on the discardable pile tip 2, and the high-pressure fluid equipment can be detachably connected to the nozzle via a pipeline. The high-pressure fluid equipment can be removed after the outer casing 1 has been driven into the soil. (Refer to...) Figure 4As shown, the upper part of the discardable pile tip 2 is provided with a mating protrusion 2-1, and the lower end of the outer casing 1 is provided with a mating slot 1-1-1 corresponding to the aforementioned mating protrusion 2-1. The discardable pile tip 2 is inserted into the mating slot 1-1-1 at the lower end of the outer casing 1 through the mating protrusion 2-1, and separates from the outer casing 1 when the discardable pile tip 2 is squeezed by the extruded concrete 7. The mating slot 1-1-1 is preferably an annular groove, and the mating protrusion 2-1 can be an annular platform, and the two can be fitted with a transition fit.

[0102] To ensure the structural strength of the outer casing 1 and the inner sleeve 4 and improve their pressure-bearing capacity, in this embodiment, the outer casing 1 is a double-walled steel casing, and the inner sleeve 4 is a double-walled steel sleeve. Specifically, refer to... Figure 3 As shown, the outer casing 1 includes an outer casing pipe 1-1a, an inner casing pipe 1-1b, and a casing interlayer support member 1-1c. The outer casing pipe 1-1a is sleeved and installed outside the inner casing pipe 1-1b, forming a casing interlayer between the outer casing pipe 1-1a and the inner casing pipe 1-1b. The casing interlayer support member 1-1c is provided within the casing interlayer. The outer casing pipe 1-1a and the inner casing pipe 1-1b are connected as a whole by the casing interlayer support member 1-1c, resulting in high structural strength. (Refer to...) Figure 7 As shown, similar to the structure of the outer casing 1, the inner sleeve 4 includes an outer sleeve tube 4-1a, an inner sleeve tube 4-1b, and a sleeve interlayer support member 4-1c. The outer sleeve tube 4-1a is sleeved and installed on the outside of the inner sleeve tube 4-1b, forming a sleeve interlayer between the outer sleeve tube 4-1a and the inner sleeve tube 4-1b. The sleeve interlayer support member 4-1c is provided within the sleeve interlayer. The outer sleeve tube 4-1a and the inner sleeve tube 4-1b are connected as a whole by the sleeve interlayer support member 4-1c, resulting in high structural strength. Both the casing interlayer support member 1-1c and the sleeve interlayer support member 4-1c are axially spaced support rings or honeycomb-shaped support plates located within the interlayer, greatly enhancing the structural strength of the outer casing 1 and the inner sleeve 4, enabling them to withstand greater pressure. Figure 3 and Figure 7 The sleeve interlayer support 1-1c and the sleeve interlayer support 4-1c shown are support rings, and a support ring is set at a certain distance for connection. Figure 8 The sleeve interlayer support 1-1c and the sleeve interlayer support 4-1c shown are honeycomb support plates. The honeycomb support plates have better load-bearing capacity, which makes the outer sleeve 1 and the inner sleeve 4 have higher structural strength.

[0103] Figure 5 A design for an outer casing 1 suitable for static pressure pile driving machine is shown. Several ribs 1-1-2 are axially spaced on the outer side wall of the casing pipe 1-1. These ribs 1-1-2 can increase the clamping force of the static pressure pile driving machine on the outer casing 1 and improve the reliability of the outer casing 1 being pressed into the soil.

[0104] In this embodiment, the aforementioned enlarged body reinforcement 5 is an expandable rigid member that can expand within the concrete enlarged body 8, thereby improving the load-bearing capacity of the rigid concrete enlarged head. Specifically, as follows... Figure 11 and Figure 12 As shown, the enlarged body reinforcement 5 includes an upper pressure plate 5-1, a guide post 5-2, a movable plate 5-3, and a support rod 5-5. The upper pressure plate 5-1 is fixed to the upper end of the guide post 5-2. The movable plate 5-3 is slidably sleeved on the guide post 5-2, allowing the movable plate 5-3 to slide freely on the guide post 5-2. The support rod 5-5 is distributed circumferentially and one end is rotatably installed below the upper pressure plate 5-1. To facilitate the installation of the support rod 5-5, a connecting ring 5-4 can be welded and fixed below the upper pressure plate 5-1. A rotating part 5-5-1 is provided at one end of the support rod 5-5. The rotating part 5-5-1 is a "C"-shaped structure with a notch, which can be locked onto the connecting ring 5-4, allowing the support rod 5-5 to rotate on the connecting ring 5-4. The other end of the support rod 5-5 passes through the corresponding through hole 5-3-1 on the movable plate 5-3. The through holes 5-3-1 on the movable plate 5-3 are distributed circumferentially, and the diameter of the circle containing each through hole 5-3-1 is larger than the diameter of the circle containing the rotating end of the support rod 5-5. This causes the support rods 5-5 to rotate and expand outwards when the movable plate 5-3 and the upper pressure plate 5-1 are relatively close. During construction, the movable plate 5-3 is placed downwards into the outer casing 1. The inner sleeve 4 presses down, pushing the upper pressure plate 5-1, guide column 5-2, and support rod 5-5 downwards. The guide column 5-2 inserts into the concrete expansion body 8, causing the movable plate 5-3 to relatively approach the upper pressure plate 5-1, thus causing the support rods 5-5 to expand outwards while being inserted into the concrete expansion body 8. The guide column 5-2 can be made of hollow tubing for easy insertion into the concrete expansion body 8. The maximum distance between the movable plate 5-3 and the upper pressure plate 5-1 can be limited by the limiting protrusion set at the free end of the support rod 5-5, so that the movable plate 5-3 will not separate from the guide post 5-2 and the support rod 5-5; of course, a pull rope can also be set between the movable plate 5-3 and the upper pressure plate 5-1, and the position of the movable plate 5-3 can be limited by the pull rope, which can also keep the movable plate 5-3 from separating from the guide post 5-2 and the support rod 5-5.

[0105] In this embodiment, the aforementioned reinforcing cage assembly 6 can be adopted. Figure 13The structure shown includes a reinforcing cage body 6-1, a grouting pipe 6-2 fixedly installed on the side wall of the reinforcing cage body 6-1, and a PVC hollow pipe 6-3 on the inner side of the reinforcing cage body 6-1. During construction, the reinforcing cage assembly 6 is hoisted into the outer casing 1, and the reinforcing cage body 6-1 is fixed with lifting rods. After pouring concrete, a reinforced concrete hollow cast-in-place pile with a rigid concrete enlarged head is formed. This reduces the amount of concrete used and lowers the manufacturing cost while ensuring the strength of the cast-in-place pile. The aforementioned enlarged body reinforcement 5 and reinforcing cage assembly 6 are both prefabricated in the factory. The manufacturing method of the reinforcing cage assembly 6 is as follows:

[0106] S0-1. According to the design drawings, fix stirrups every a meters along the length direction; the interval a between stirrups can be determined according to the design requirements. Generally, one stirrup can be fixed every 2 meters.

[0107] S0-2. Install PVC hollow pipe 6-3 in the middle of the stirrup. PVC hollow pipe 6-3 is composed of several PVC pipe sections connected together. Adjacent PVC pipe sections are connected by PVC pipe joints. The length of each PVC pipe section can be determined as needed. For example, the length of each PVC pipe section can be designed to be 9 meters.

[0108] S0-3 After installing the stirrups and PVC hollow pipe 6-3, weld the main reinforcement bars onto the stirrups. Adjacent main reinforcement bars in the same length direction are connected by sleeves.

[0109] S0-4. After the main reinforcement is welded, the spiral reinforcement is welded and fixed to form a steel cage assembly 6 with a PVC hollow pipe 6-3 in the middle. The grouting pipe 6-2 can be tied to the side wall of the main body of the steel cage 6-1, and two or more grouting pipes 6-2 can be set.

[0110] This embodiment also relates to a cast-in-place pile. This cast-in-place pile is manufactured using the aforementioned YKP method for cast-in-place pile construction. The structure of this cast-in-place pile is similar to... Figure 21 The state shown includes a pile body and a rigid concrete enlarged head located at the lower part of the pile body. The rigid concrete enlarged head includes a concrete enlarged body 8 and an enlarged body reinforcement 5 embedded in the concrete enlarged body 8. The lower part of the rigid concrete enlarged head also has a discarded pile tip 2. The pile body has a steel cage assembly 6 inside and a cement-soil outer ring outside the pile body.

[0111] This invention discloses a YKP method for constructing cast-in-place piles and the resulting cast-in-place piles. The method involves pressing an outer casing into the soil using a static pressure pile driver or a non-resonant hydraulic vibratory hammer to form a pile hole. An inner sleeve is then used to press extrusion concrete from the outer casing into the soil to form a concrete enlargement. Simultaneously, reinforcing members are pressed into the enlargement to form a rigid concrete enlargement head. A reinforcing cage assembly is then placed inside the outer casing, and concrete is poured. After the concrete has initially set, the outer casing is removed, and grouting pipes are used to fill the side gaps with concrete, forming a cement-soil outer ring. This method solves the problems of high noise and severe environmental pollution associated with existing construction methods. Furthermore, by directly pressing the outer casing into the hole, there is no collapse, sediment, or necking issues affecting quality, resulting in reliable pile quality. The cast-in-place pile has a cement-soil outer ring on the outside, which significantly increases the frictional resistance between the pile and the surrounding soil. The rigid concrete enlargement head also effectively improves the bearing capacity of the cast-in-place pile. Compared with existing cast-in-place pile construction technology, the construction efficiency is increased by 200% to 300%, and the construction quality is reliably guaranteed; the bearing capacity of the pile foundation is significantly improved by 10% to 50%; green and pollution-free construction is achieved, and the construction cost is significantly reduced, resulting in significant economic and social benefits.

[0112] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A YKP method for constructing cast-in-place piles, characterized in that: The system includes auxiliary construction tools and precast pile reinforcement components. The auxiliary construction tools include an outer casing (1), a discardable pile tip (2), and an inner sleeve (4). The discardable pile tip (2) is inserted into the lower end of the outer casing (1). The outer wall shape and size of the inner sleeve (4) are adapted to the inner wall shape and size of the outer casing (1), and the lower end of the inner sleeve (4) is closed. The precast pile reinforcement components include an enlarged reinforcement component (5) and a steel cage assembly (6). The steel cage assembly (6) has a grouting pipe (6-2). The enlarged reinforcement component (5) is an expandable rigid component, including an upper pressure plate (5-1), a guide column (5-2), a movable plate (5-3), and a support rod (5-5). The upper pressure plate (5-1) is fixed to the upper end of the guide post (5-2), the movable plate (5-3) is slidably sleeved on the guide post (5-2), the support rod (5-5) is distributed circumferentially and one end is rotatably installed below the upper pressure plate (5-1), and the other end of the support rod (5-5) passes through the corresponding through hole (5-3-1) on the movable plate (5-3). The through holes (5-3-1) on the movable plate (5-3) are distributed circumferentially, and the diameter of the circle where each through hole (5-3-1) is located is larger than the diameter of the circle where the rotating end of the support rod (5-5) is located, so that when the movable plate (5-3) and the upper pressure plate (5-1) are relatively close, each support rod (5-5) rotates outward and expands. The specific construction method includes the following steps: S1. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press the outer casing (1) with the discardable pile tip (2) into the soil to form a pile hole in the soil. S2. First, a certain amount of extruded concrete (7) is poured into the outer casing (1), and then the inner sleeve (4) is inserted into the outer casing (1); S3. Use a static pressure pile driver or a non-resonance hydraulic vibratory hammer to press down the inner sleeve (4) and press the extruded concrete (7) in the outer casing (1) into the soil to form a concrete enlarged body (8). At this time, the discarded pile tip (2) is separated from the outer casing (1) and left in the concrete enlarged body (8). S4. Take out the inner sleeve (4) and place the expansion body reinforcement (5) into the outer casing (1). Then, use the inner sleeve (4) again to press the expansion body reinforcement (5) into the concrete expansion body (8) to form a rigid concrete expansion head. During construction, place the movable plate (5-3) downward into the outer casing (1). The inner sleeve (4) presses down to push the upper pressure plate (5-1), guide column (5-2) and support rod (5-5) downward. The guide column (5-2) is inserted into the concrete expansion body (8), so that the movable plate (5-3) is relatively close to the upper pressure plate (5-1), causing each support rod (5-5) to be inserted into the concrete expansion body (8) and expand outward at the same time. S5. Take out the inner sleeve (4), put the steel cage assembly (6) into the outer sleeve (1), and fix the steel cage assembly (6); S6. Pour concrete from bottom to top to the design elevation or above; S7. After the concrete has initially set in step S6, the outer casing (1) is pulled out using a static pressure pile driver or a non-resonance hydraulic vibratory hammer. After the outer casing (1) is pulled out, grout is injected into the pores after the outer casing (1) is pulled out through the grouting pipe (6-2) to fill the side gap concrete (9) and form a cement-soil outer ring.

2. The YKP method for constructing cast-in-place piles according to claim 1, characterized in that: The outer casing (1) is composed of several casing pipe sections (1-1) connected together. Adjacent casing pipe sections (1-1) are connected by a cylinder connection assembly (3). The discardable pile tip (2) is installed at the lower end of the first casing pipe section (1-1). During construction, the first casing pipe section (1-1) is first pressed into the soil, and then the next casing pipe section (1-1) is lifted and connected to the previous casing pipe section (1-1) through the cylinder connection assembly (3). The casing is then pressed in until the designed pile top elevation is reached.

3. The YKP method for constructing cast-in-place piles according to claim 2, characterized in that: The cylindrical connecting assembly (3) includes a male connector (3-1), a male connector gasket (3-2), a pin (3-3), a female connector (3-4), and a female connector gasket (3-5). The male connector (3-1) and the female connector (3-4) are respectively fixedly installed at the ends of two adjacent sections of the protective cylinder fitting (1-1). The male connector (3-1) can be axially inserted into the female connector (3-4). The outer periphery of both the male connector (3-1) and the female connector (3-4) is provided with several connecting rings. The male connector gasket (3-2) is fixed in the corresponding connection hole of the male connector (3-1), and the female connector gasket (3-5) is fixed in the corresponding connection hole of the female connector (3-4). After the male connector (3-1) and the female connector (3-4) are inserted, the positions of the male connector gasket (3-2) and the female connector gasket (3-5) correspond one-to-one, and the pin (3-3) is correspondingly installed in the pin holes of the male connector gasket (3-2) and the female connector gasket (3-5).

4. The YKP method for constructing cast-in-place piles according to claim 1, characterized in that: The discardable pile tip (2) is also equipped with a high-pressure water jet. When encountering hard soil layers, the high-pressure water jet is activated to cut and break the soil to assist in pile driving. The upper part of the discardable pile tip (2) is provided with a mating protrusion (2-1), and the lower end of the outer casing (1) is provided with a mating slot (1-1-1) corresponding to the above-mentioned mating protrusion (2-1). The discardable pile tip (2) is installed in the mating slot (1-1-1) at the lower end of the outer casing (1) by inserting the mating protrusion (2-1). When the discardable pile tip (2) is squeezed by the extrusion concrete (7), it separates from the outer casing (1).

5. The YKP method for constructing cast-in-place piles according to claim 1, characterized in that: The outer casing (1) is a double-walled steel casing, including an outer casing tube (1-1a), an inner casing tube (1-1b), and a casing interlayer support (1-1c). The outer casing tube (1-1a) is sleeved on the outside of the inner casing tube (1-1b), and a casing interlayer is formed between the outer casing tube (1-1a) and the inner casing tube (1-1b). The casing interlayer support (1-1c) is provided inside the casing interlayer. The inner sleeve (4) is a double-walled steel sleeve, including an outer sleeve tube (4-1a), an inner sleeve tube (4-1b), and a sleeve interlayer support (4-1c). The outer sleeve tube (4-1a) is sleeved on the outside of the inner sleeve tube (4-1b), and a sleeve interlayer is formed between the outer sleeve tube (4-1a) and the inner sleeve tube (4-1b). The sleeve interlayer support (4-1c) is provided inside the sleeve interlayer. The sleeve interlayer support (1-1c) and the sleeve interlayer support (4-1c) are both support rings spaced apart along the axial direction or honeycomb support plates located in the interlayer.

6. The YKP method for constructing cast-in-place piles according to claim 1, characterized in that: The steel cage assembly (6) includes a steel cage body (6-1), and the grouting pipe (6-2) is fixedly installed on the side wall of the steel cage body (6-1). The inner side of the steel cage body (6-1) is also provided with a PVC hollow pipe (6-3). During construction, the steel cage assembly (6) is hoisted into the outer casing (1), and the steel cage body (6-1) is fixed with a hoisting bar. After pouring concrete, a reinforced concrete hollow cast-in-place pile with a rigid concrete enlarged head is formed.

7. The YKP method for constructing cast-in-place piles according to claim 6, characterized in that: The manufacturing method of the steel cage assembly (6) is as follows: S0-1, every [time] along the length direction a Meter-fixed stirrups; S0-2. Install a PVC hollow pipe (6-3) in the middle of the stirrup. The PVC hollow pipe (6-3) is composed of several PVC pipe sections connected together. Adjacent PVC pipe sections are connected by PVC pipe joints. S0-3 After installing the stirrups and PVC hollow pipes (6-3), weld the main reinforcement bars onto the stirrups. Adjacent main reinforcement bars in the same length direction are connected by sleeves. S0-4. After the main reinforcement is welded, the spiral reinforcement is welded and fixed.

8. A cast-in-place pile manufactured using the YKP method of construction as described in any one of claims 1 to 7.

9. The cast-in-place pile according to claim 8, characterized in that: The cast-in-place pile includes a pile body and a rigid concrete enlarged head located at the lower part of the pile body. The rigid concrete enlarged head includes a concrete enlarged body (8) and an enlarged body reinforcement (5) embedded in the concrete enlarged body (8). The lower part of the rigid concrete enlarged head also has a discarded pile tip (2). The pile body has a steel cage assembly (6) inside and a cement-soil outer ring outside the pile body.

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