Precast pile splicing structure and method

Abstract

The invention discloses a precast pile splicing structure and a precast pile splicing method which are applied to a basement structure. The precast pile is of a hollow cylindrical structure and is arranged in a foundation below a basement cushion layer. A PVC corrugated pipe is adopted as the cylindrical formwork, the cylindrical formwork is arranged on the protruding part of the prefabricated pile in a sleeving mode and arranged in the foundation pit, and the cylindrical formwork and the prefabricated pile share the same central axis; the frustum template is mounted at the top of the cylindrical template, the frustum template and the precast pile are arranged in a manner of sharing a central axis, and a hollow area of the precast pile, the cylindrical templates and the other cylindrical templates form a pouring area of the pile splicing structure; a pile core reinforcement cage is arranged in the pouring area, and the pile core reinforcement cage sequentially penetrates through the cylindrical formwork and the frustum formwork from the hollow area of the precast pile; concrete is poured in the pouring area to form a pile splicing structure with a lower cylinder and an upper frustum, and a cushion layer is poured on the foundation; the waterproof structure is laid on the surfaces of the basement cushion layer and the upper frustum structure. The construction process can be simplified, and the construction cost is reduced; in addition, secondary construction at the internal corner and hollowing of the waterproof structure at the pile head are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of basement construction, and in particular to a prefabricated pile connection structure and a pile connection method. Background Art

[0002] Precast piles are prefabricated in prefabricated component processing plants, and after curing and reaching the designed strength, they are transported to the construction site, driven into the soil with a pile driver, and then the cap beam (slab) foundation is poured on the top of the pile. Reinforced concrete precast piles have the advantages of easy production, high strength, high rigidity and can be made into various cross-sectional shapes. They are a widely used type of pile. During the construction of precast piles, there is a possibility that the precast piles are driven too deep due to design or operation deviations. At this time, the pile connection process is usually used to achieve the designed height. However, the formwork erection operation in the pile connection process is difficult and the process is cumbersome, which affects the construction period. The formed structure after the pile connection usually does not meet the requirements of the next step of the waterproof base and requires secondary treatment.

[0003] In addition, in order to improve its mechanical properties, it is usually necessary to process the core. The core pouring process is easy to contaminate the anchor steel bars, which requires secondary cleaning. The steel bars in the precast pile core are too dense, making the vibration operation difficult. Because there is a negative angle between the precast pile and the concrete cushion layer, the foundation waterproof layer is directly laid, which is easy to produce hollows at the pile head, causing leakage of the pile head waterproofing. Summary of the invention

[0004] In view of the above-mentioned defects in the prior art, a prefabricated pile connection structure and a pile connection method are provided to simplify the construction process and reduce construction costs; in addition, secondary construction at the inner corners and hollowing of the waterproof structure at the pile head are avoided.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] First, prefabricated pile-to-pile structure is used in basement structure;

[0007] include

[0008] Precast piles, which are hollow cylindrical structures, are placed in the foundation below the basement cushion layer. A foundation pit is dug in the basement cushion layer foundation with the precast pile as the center, and the top of the precast pile protrudes from the bottom of the foundation pit by a set height.

[0009] The column formwork and the frustum formwork, the column formwork adopts PVC (polyvinyl chloride) corrugated pipe, the column formwork is sleeved on the protruding part of the pre-installed pile and is arranged in the foundation pit, and the column formwork and the precast pile are arranged on the same central axis; the frustum formwork is installed on the top of the column formwork, and the frustum formwork and the precast pile are arranged on the same central axis, and the hollow area of ​​the precast pile, the column formwork and the column formwork constitute the pouring area of ​​the pile connection structure; the small end face of the frustum formwork faces upward, and the height of the small end face is higher than the upper surface of the basement cushion layer; the foundation pit area outside the formwork is filled with backfill soil;

[0010] A pile core steel cage is provided in the casting area, and the pile core steel cage passes through the column formwork and the frustum formwork in sequence from the hollow area of ​​the precast pile, and anchor steel bars are also extended along the top of the pile core steel cage; concrete is poured in the casting area to form a pile connection structure of a lower cylinder and an upper frustum, and a cushion layer is poured on the foundation;

[0011] Waterproof structure: the waterproof structure is laid on the surface of the basement cushion layer and the upper frustum structure.

[0012] According to the above technical scheme, a concrete fixing seat of a set height is cast on the outside of the cylindrical formwork at the bottom of the foundation pit. The concrete fixing seat is located at the bottom of the foundation pit. Backfill soil is filled in the area of ​​the foundation pit above the concrete fixing seat to the elevation of the basement cushion foundation.

[0013] According to the above technical solution, the projection of the top surface of the upper frustum on the horizontal plane coincides with the projection of the lower cylinder on the horizontal plane; the angle between the generatrix of the side surface of the upper frustum and the horizontal plane ranges from 120° to 150°; the frustum template adopts a wooden template.

[0014] According to the above technical solution, the lower surface of the upper cone is flush with the bottom surface of the basement cushion layer, and the elevation of the upper surface of the lower cone is at least 50 mm higher than the upper elevation of the basement cushion layer.

[0015] According to the above technical scheme, the waterproof structure includes waterproof mortar and a first waterproof coating applied on the upper cone, a second waterproof coating applied on the basement cushion layer, a waterproof membrane laid on the basement cushion layer and the inner corner of the upper cone, and a polysulfide sealing paste used for closing the waterproof membrane on the side of the upper cone; waterproof mortar is applied on the upper surface of the upper cone within a range at least 100 mm larger than the pile head diameter, and the first waterproof coating is applied within a set range on the waterproof mortar and around the waterproof mortar; the inner side of the waterproof membrane is overlapped with the area where the first waterproof coating is applied on the upper cone through the polysulfide sealing paste, and the outer side of the waterproof membrane is overlapped with the area where the second waterproof coating is applied on the basement cushion layer.

[0016] According to the above technical solution, it also includes a steel bar protection structure, which uses a PVC pipe protective cover. The PVC pipe protective cover is installed on the anchor steel bar of the pile core steel cage that is higher than the upper cone.

[0017] In the second aspect, the prefabricated pile connection method comprises:

[0018] A cylindrical formwork of a lower cylinder is fixedly installed on the outer side of the precast pile, and the central axis of the cylindrical formwork coincides with the central axis of the precast pile;

[0019] Fill the foundation pit outside the column formwork with backfill soil to the set height;

[0020] A frustum formwork is installed on the top of the column formwork, and the central axis of the frustum formwork coincides with the central axis of the precast pile;

[0021] The pile core reinforcement cage is placed in the hollow precast pile, column formwork and cone formwork, and concrete is poured to form the pile connection structure.

[0022] According to the above technical scheme, after the installation of the column formwork and before the backfill soil is backfilled, a concrete fixing seat of a set height is poured on the outside of the column formwork in the foundation pit; the backfill soil is backfilled in layers and manually compacted to the foundation design requirements.

[0023] According to the above technical solution, a dewatering well is provided near the pile connection portion, and the water level in the dewatering well is controlled at 500mm to 1000mm below the bottom of the foundation pit.

[0024] According to the above technical solution, after the pile core reinforcement cage is placed and before the concrete is poured, a PVC pipe protective sleeve is installed on the anchoring reinforcement of the pile core reinforcement cage located above the upper cone.

[0025] The present invention has the following beneficial effects:

[0026] 1. The pile connection structure adopts a lower cylinder and an upper cone structure. The lower cylinder uses a PVC corrugated pipe as a column template, which simplifies the construction process and reduces construction costs compared to the existing technology of building a brick mold in the foundation pit to construct the pile connection structure.

[0027] In addition, compared with the prior art, the pile connection structure is a cylindrical structure, and the inner angle between the pile connection structure and the basement cushion layer is a right angle. Before waterproofing construction, the inner angle needs to be processed to make it a smooth curved surface or an obtuse connecting surface, so as to facilitate the construction of waterproof materials; the top of the present application adopts a frustum structure, and the side of the frustum structure is an inclined curved surface, and the contact surface with the upper surface of the basement cushion layer is an obtuse angle, which omits the process of processing the inner angle, reduces the construction difficulty and improves the construction efficiency. And in the prior art, after the right-angle inner angle is plastered, due to the difference in concrete grades, the plastering structure at the inner angle is prone to cracking, thereby destroying the waterproof structure. Therefore, this structure can avoid hollowing of the waterproof structure at the pile head.

[0028] 2. Install a PVC pipe protective cover on the outside of the anchor steel bar during the core pouring of the precast pile and before the installation of the water-swelling rubber waterstop ring on the anchor steel bar to avoid contamination of the anchor steel bar during the core pouring, cushion pouring and waterproofing operations, and avoid secondary cleaning.

[0029] 3. The waterproof membrane is extended to the side wall of the pile head and sealed with polysulfide sealant to ensure the airtightness of the waterproofing and improve the waterproofing effect of the pile head.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 It is a structural schematic diagram of foundation pit excavation according to an embodiment of the present invention;

[0033] Figure 2 It is a schematic diagram of a concrete fixing seat, foundation pit backfilling, and template installation according to an embodiment of the present invention;

[0034] Figure 3 It is a plan view of the template installation of the pile connection part of the embodiment provided by the present invention;

[0035] Figure 4 The invention provides a pile core reinforcement cage installation and concrete pouring embodiment;

[0036] Figure 5 It is a construction schematic diagram of a pile head waterproof structure after pile connection according to an embodiment of the present invention;

[0037] Figure 6 It is a schematic diagram of pouring concrete for a pile cap according to an embodiment of the present invention;

[0038] In the figure, 1. foundation of basement foundation; 2. precast piles; 2-1. hollow area of ​​precast piles; 3. basement cushion; 4. foundation pit; 5. columnar formwork; 5-1. lower cylinder; 6. frustum formwork; 6-1. upper frustum; 7. backfill soil; 8. pile core steel cage; 8-1. anchoring steel bars; 8-2. steel plate base; 9. waterproof structure; 9-1. waterproof mortar; 9-2. first waterproof coating; 9-3. second waterproof coating; 9-4. waterproof membrane; 9-5. polysulfide sealant; 10. concrete fixing seat; 11. water-swelling rubber water stop ring; 12. pile cap; 13. steel protection structure. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-6The principles and features of the present invention are described, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. In the following paragraphs, the present invention is described in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0040] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] Reference Figure 1 to Figure 6 As shown, the prefabricated pile connection structure provided by the present invention.

[0043] Example 1

[0044] Applied to the basement structure; excavation to the basement foundation pit to the design elevation, and then the basement cushion layer is constructed on the basement foundation 1. Before the basement cushion layer construction, prefabricated pile connection construction is required.

[0045] Prefabricated pile connection structure includes

[0046] The precast pile 2 has a hollow cylindrical structure and is placed in the foundation below the basement cushion 3. A foundation pit 4 is dug in the basement cushion foundation with the precast pile as the center, and the top of the precast pile protrudes from the bottom of the foundation pit by a set height.

[0047] The size of the foundation pit must meet the following conditions: the head of the precast pile protrudes at least 300mm from the bottom of the foundation pit, and the edge of the bottom of the foundation pit is at least 300mm away from the edge of the head of the precast pile. The slope of the foundation pit should be adjusted according to the soil quality and depth, and the excavation surface should be cleaned and leveled.

[0048] The column formwork 5 and the frustum formwork 6, the column formwork adopts PVC corrugated pipe, the column formwork is sleeved on the protruding part of the prefabricated pile and is arranged in the foundation pit, and the column formwork and the prefabricated pile are arranged on the same central axis; the frustum formwork is installed on the top of the column formwork, and the frustum formwork and the prefabricated pile are arranged on the same central axis, the hollow area 2-1 of the prefabricated pile, the column formwork and the column formwork constitute the casting area of ​​the pile connection structure; the small end face of the frustum formwork faces upward, and the height of the small end face is higher than the upper surface of the basement cushion layer; the foundation pit area outside the formwork is filled with backfill soil 7.

[0049] A pile core steel cage 8 is provided in the casting area. The pile core steel cage passes through the column formwork and the cone formwork in sequence from the hollow area of ​​the precast pile, and anchor steel bars 8-1 extend along the top of the pile core steel cage. Concrete is poured in the casting area to form a pile connection structure of the lower column 5-1 and the upper cone 6-1, and a cushion layer is poured on the foundation.

[0050] The waterproof structure 9 is laid on the surface of the basement cushion layer and the upper frustum structure.

[0051] The external pile cap is cast on the upper cone and basement cushion.

[0052] In this embodiment, the pile connection structure adopts a lower cylinder and an upper cone structure. The lower cylinder uses a PVC corrugated pipe as a column formwork, which simplifies the construction process and reduces the construction cost compared to the prior art of building a brick formwork in the foundation pit to construct the pile connection structure.

[0053] In addition, compared with the prior art, the pile connection structure is a cylindrical structure, and the inner angle between the pile connection structure and the basement cushion layer is a right angle. Before waterproofing construction, the inner angle needs to be processed to make it a smooth curved surface or an obtuse angle connection surface, so as to facilitate the construction of waterproof materials; the top of the present application adopts a frustum structure, and the side of the frustum structure is an inclined curved surface, and the contact surface with the upper surface of the basement cushion layer is an obtuse angle, which omits the process of processing the inner angle, reduces the construction difficulty and improves the construction efficiency. And in the prior art, after the right-angle inner angle is plastered, due to the difference in concrete grades, the plastering structure at the inner angle is prone to cracking, thereby destroying the waterproof structure. Therefore, this structure can avoid hollowing of the waterproof layer at the pile head.

[0054] Example 2

[0055] The structure and principle of Example 2 are similar to those of Example 1, except that in order to fix the cylindrical formwork in the foundation pit, a concrete fixing seat 10 of a set height is cast at the bottom of the foundation pit and located outside the cylindrical formwork. The concrete fixing seat is located at the bottom of the foundation pit, and backfill soil is filled in the area of ​​the foundation pit above the concrete fixing seat to the elevation of the basement cushion foundation.

[0056] Example 3

[0057] The structure and principle of Example 3 are similar to those of Example 1, except that: in order to facilitate the design of the pile connection structure and the disassembly and assembly of the frustum formwork, the projection of the top surface of the upper frustum on the horizontal plane coincides with the projection of the lower cylinder on the horizontal plane; preferably, the angle between the generatrix of the side surface of the upper frustum and the horizontal plane is in the range of 120° to 150°, and other angles may also be used, but the waterproof structure construction effect is not as good as that in the above range; the frustum formwork adopts a wooden formwork.

[0058] In Example 1-3, the lower surface of the upper cone is flush with the bottom surface of the basement cushion layer, and the elevation of the upper surface of the lower cone is at least 50 mm higher than the upper elevation of the basement cushion layer.

[0059] In Examples 1-3, the waterproof structure includes a waterproof mortar 9-1 and a first waterproof coating 9-2 applied on the upper cone, a second waterproof coating 9-3 applied on the basement cushion layer, a waterproof membrane 9-4 laid on the basement cushion layer and the inner corner of the upper cone, and a polysulfide sealant 9-5 used for closing the waterproof membrane on the side of the upper cone; the waterproof mortar is applied on the upper surface of the upper cone within a range at least 100 mm larger than the pile head diameter, and the first waterproof coating is applied on the waterproof mortar and within a set range around the waterproof mortar; the inner side of the waterproof membrane is overlapped on the area where the first waterproof coating is applied on the upper cone through the polysulfide sealant, and the outer side of the waterproof membrane is overlapped on the area where the second waterproof coating is applied on the basement cushion layer.

[0060] Example 4

[0061] The structure and principle of Example 4 are similar to those of the above-mentioned embodiments, except that it also includes a steel bar protection structure 13, which adopts a PVC pipe protective sleeve, and a PVC pipe protective sleeve is installed on the anchor steel bar of the pile core steel cage higher than the upper cone.

[0062] The earthwork is excavated to the basement foundation pit to the designed elevation, and then the basement cushion layer is constructed on the basement foundation. Before the basement cushion layer is constructed, prefabricated pile connection construction is required. The present invention provides a prefabricated pile connection method, which includes:

[0063] S1: Dig a foundation pit on the basement foundation. Dig a foundation pit on the basement foundation according to the area where the precast piles are located. The foundation pit must meet the following conditions: the head of the precast pile protrudes at least 300mm from the bottom of the foundation pit, and the edge of the bottom of the foundation pit is at least 300mm away from the edge of the head of the precast pile. Adjust the earthwork slope of the foundation pit according to the soil quality and depth, and clean and level the excavation surface. Before the excavation of the foundation pit, a dewatering well is set near the pile connection; during the excavation of the foundation pit, the water level in the dewatering well is controlled at 500mm to 1000mm below the bottom of the foundation pit to ensure the safety of the foundation pit at the pile connection and avoid collapse.

[0064] S2: After the core of the precast pile is cleaned, the lower cylindrical formwork is installed. The cylindrical formwork uses a PVC corrugated pipe with an inner diameter of the pile outer diameter + 100mm (other sizes can also be used as required) to ensure that the formwork coincides with the central axis of the precast pile and the installation is smooth.

[0065] Pour concrete between the outer side of the lower cylindrical formwork and the side wall of the foundation pit to form a concrete fixing seat; the thickness of the concrete fixing seat is 100mm (other sizes can also be used according to needs) to ensure that the bottom of the bottom cylindrical formwork is fixed and the formwork does not float or move during the core pouring process. After the concrete fixing seat reaches the design strength, the original soil is backfilled in layers and compacted manually to the foundation design requirements. Mechanical compaction is not allowed to reduce the disturbance of the surrounding soil and ensure the protection of the finished PVC corrugated pipe.

[0066] S3: Install the upper frustum formwork. The frustum formwork coincides with the central axis of the precast pile; the top surface of the frustum formwork is preferably the same as the cross-sectional size of the bottom cylindrical formwork. The material of the frustum formwork can be wooden formwork, and steel formwork, aluminum formwork, and plastic formwork should be avoided as much as possible. The molding surface should be designed to reduce pores and avoid secondary treatment of the waterproof base. In order to ensure that the frustum structure is at least 50mm higher than the cushion layer, the bottom surface of the upper formwork of the frustum formwork is not lower than the upper surface of the cushion layer by 50mm, and the upper surface of the lower formwork of the frustum formwork is flush with the bottom surface of the basement cushion layer.

[0067] S4: Processing and installation of pile core steel cage. The size of the steel plate base 8-2 of the pile core steel cage is slightly smaller than the inner diameter of the precast pile, and the length of the pile core steel cage is determined according to the design requirements. The steel cage extends out of the cushion layer by 50mm to ensure the height of the pile foundation anchored into the pedestal and control the thickness of the foundation steel protection layer. The length of the anchor steel bar at the top of the steel cage is set according to the design and specification requirements. The PVC pipe protective sleeve is installed outside the anchor steel bar. The protective sleeve is installed before the precast pile core is poured and removed before the water-expanding rubber water stop ring 11 is installed on the anchor steel bar. The inner diameter of the PVC pipe protective sleeve is slightly larger than the diameter of the anchor steel bar, and the length of the PVC pipe protective sleeve is slightly larger than the protruding length of the anchor steel bar, so that it is convenient to remove it at any time. The top of the PVC pipe protective sleeve can be closed, and the closing method is not limited.

[0068] S5: Casting of the pile connection structure. The hollow area of ​​the precast pile, the column formwork and the column formwork constitute the pouring area of ​​the pile connection structure, and the concrete is poured and vibrated in layers to the pile head. Before pouring and vibrating the core, the anchor steel bars are bent according to the requirements of the atlas or drawings; after bending, an operating space is provided for the vibration of the core pouring concrete, and the concrete is poured to the top surface of the designed pile head, and the surface is smoothed. The core pouring concrete is impermeable concrete, and the concrete strength is calculated according to the design.

[0069] S6: After the concrete of the pile connection structure reaches the design strength, the top and side forms of the cone formwork are removed, and the bottom formwork and cylindrical formwork of the cone formwork are retained in the pile connection structure. Then, the basement cushion is poured on the basement foundation, and the basement cushion is attached to the side of the cone.

[0070] S7: Construction of waterproof structure. First, treat the pile head base of the connecting pile structure, first apply the waterproof mortar made of polymer cement, the range is the pile head diameter + 300mm; then apply the first waterproof coating made of cement-based penetrating crystallization, the range is the pile head diameter + 150mm. After the waterproof mortar and the first waterproof coating of the pile head of the connecting pile structure are dry, the basement foundation waterproof pre-paving construction is carried out, and the second waterproof coating made of non-curing rubber asphalt is applied on the basement cushion layer, and then the waterproof membrane pre-paved with SBS (styrene block copolymer) modified asphalt is laid at the connection between the basement cushion layer and the upper cone. The waterproof membrane is thrown to the side wall of the pile head and closed with polysulfide sealant.

[0071] S8: Remove the protective cover of the PVC pipe, install the water-expanding rubber water stop ring on the anchor steel bar, tie the steel bars of the pile cap 12 foundation and pour the concrete.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. Prefabricated pile-to-pile structure, used in basement structure; Features: include Precast piles, which are hollow cylindrical structures, are placed in the foundation below the basement cushion layer. A foundation pit is dug in the basement cushion layer foundation with the precast pile as the center, and the top of the precast pile protrudes from the bottom of the foundation pit by a set height. The column formwork and the frustum formwork, the column formwork adopts PVC corrugated pipe, the column formwork is sleeved on the protruding part of the pre-installed pile and is arranged in the foundation pit, and the column formwork and the precast pile are arranged on the same central axis; the frustum formwork is installed on the top of the column formwork, and the frustum formwork and the precast pile are arranged on the same central axis, and the hollow area of ​​the precast pile, the column formwork and the column formwork constitute the pouring area of ​​the pile connection structure; the small end face of the frustum formwork faces upward, and the height of the small end face is higher than the upper surface of the basement cushion layer; the foundation pit area outside the formwork is filled with backfill soil; A pile core steel cage is provided in the casting area, and the pile core steel cage passes through the column formwork and the frustum formwork in sequence from the hollow area of ​​the precast pile, and anchor steel bars are also extended along the top of the pile core steel cage; concrete is poured in the casting area to form a pile connection structure of a lower cylinder and an upper frustum, and a cushion layer is poured on the foundation; Waterproof structure: the waterproof structure is laid on the surface of the basement cushion layer and the upper frustum structure.

2. The prefabricated pile connection structure according to claim 1, characterized in that: A concrete fixing seat of a set height is cast on the outside of the cylindrical formwork at the bottom of the foundation pit. The concrete fixing seat is located at the bottom of the foundation pit. Backfill soil is filled in the area of ​​the foundation pit above the concrete fixing seat to the elevation of the basement cushion foundation.

3. The prefabricated pile connection structure according to claim 1, characterized in that: The projection of the top surface of the upper frustum on the horizontal plane coincides with the projection of the lower cylinder on the horizontal plane; the angle between the generatrix of the side surface of the upper frustum and the horizontal plane ranges from 120° to 150°; the frustum template adopts a wooden template.

4. The prefabricated pile connection structure according to claim 2, characterized in that: The lower surface of the upper cone is flush with the bottom surface of the basement cushion layer, and the elevation of the upper surface of the lower cone is at least 50mm higher than the upper elevation of the basement cushion layer.

5. The prefabricated pile connection structure according to claim 1, characterized in that: The waterproof structure includes waterproof mortar and a first waterproof coating applied on the upper cone, a second waterproof coating applied on the basement cushion layer, waterproof membrane laid on the basement cushion layer and the inner corner of the upper cone, and polysulfide sealing paste used for closing the waterproof membrane on the side of the upper cone; waterproof mortar is applied on the upper surface of the upper cone within a range at least 100 mm larger than the pile head diameter, and the first waterproof coating is applied within a set range on the waterproof mortar and around the waterproof mortar; the inner side of the waterproof membrane is overlapped on the area where the first waterproof coating is applied on the upper cone through the polysulfide sealing paste, and the outer side of the waterproof membrane is overlapped on the area where the second waterproof coating is applied on the basement cushion layer.

6. The prefabricated pile connection structure according to claim 1, characterized in that: It also includes a steel bar protection structure, which uses a PVC pipe protection cover. The PVC pipe protection cover is set on the anchor steel bar of the pile core steel cage that is higher than the upper cone.

7. A prefabricated pile connection method, characterized in that: include, A cylindrical formwork of a lower cylinder is fixedly installed on the outer side of the precast pile, and the central axis of the cylindrical formwork coincides with the central axis of the precast pile; Fill the foundation pit outside the column formwork with backfill soil to the set height; A frustum formwork is installed on the top of the column formwork, and the central axis of the frustum formwork coincides with the central axis of the precast pile; The pile core reinforcement cage is placed in the hollow precast pile, column formwork and cone formwork, and concrete is poured to form the pile connection structure.

8. The prefabricated pile connection method according to claim 7, characterized in that: After the column formwork is installed and before the backfill soil is backfilled, a concrete fixing seat of a set height is poured on the outside of the column formwork in the foundation pit; the backfill soil is backfilled in layers and manually compacted to the foundation design requirements.

9. The prefabricated pile connection method according to claim 7, characterized in that: A dewatering well is provided near the pile connection part, and the water level in the dewatering well is controlled at 500mm~1000mm below the bottom of the foundation pit.

10. The prefabricated pile connection method according to claim 7, characterized in that: After the pile core reinforcement cage is placed and before the concrete is poured, a PVC pipe protective sleeve is installed on the anchor reinforcement of the pile core reinforcement cage located above the upper cone.

Images