A rammed pile structure

Abstract

The invention discloses a rammed and expanded pile structure. The structure comprises the following steps: leveling the site and positioning the lines before construction, digging out the pile hole and the expanded head, placing the crushed stone layer, and performing preliminary tamping. The outer cylinder is placed, and a cone formed by a plurality of outer expansion plates is inserted into the crushed stone layer to a designed depth, so that the inner cylinder resists the outer expansion plates, the outer expansion plates are further opened, and the surrounding crushed stone layer is rammed and expanded in a horizontal direction. The inner cylinder is taken out, and the concrete cushion layer is poured in the outer cylinder. The precast pile is placed in the pile hole, embedded in the crushed stone layer, and connected with the concrete cushion layer. The cast-in-place concrete layer is then poured in layers into the outer cylinder. The outer cylinder is lifted while pouring, and vibrated to improve the connectivity between the precast pile and the bottom expanded head and the side soil layer, thereby avoiding the concrete segregation of the core bearing part and affecting the bearing strength of the pile.

Description

Technical Field

[0001] The invention relates to the field of building construction structures, and in particular to a rammed-and-expanded pile structure. Background Art

[0002] Rammed-and-expanded piles are filled with construction waste, slag, soil, lime, ash soil, non-toxic industrial waste and their mixtures, which are filled in pile holes that have been pre-drilled to a predetermined depth to form a dense pile body with high bearing capacity and strongly compacted inter-pile soil. Concrete is then poured in layers in the hole to form the pile. However, after the construction of some rammed-and-expanded piles, the strength of some parts of the pile body does not meet the design requirements, resulting in the pile being a waste pile. Summary of the invention

[0003] The purpose of the present invention is to provide a rammed-and-expanded pile structure, aiming to solve the technical problem in the prior art that the pile body strength of some rammed-and-expanded piles does not meet the design requirements after construction, resulting in the piles becoming waste piles.

[0004] To achieve the above-mentioned purpose, the present invention adopts a rammed and expanded pile structure, including a soil layer, a crushed stone layer, a steel casing, a precast concrete component and a connecting component, wherein the crushed stone layer is fixedly connected to the soil layer and is located inside the soil layer, the steel casing is slidably connected to the soil layer and is engaged with the crushed stone layer, the precast concrete component is slidably connected to the steel casing and is located inside the steel casing, the connecting component is fixedly connected to the precast concrete component and is fixedly connected to the soil layer and is located between the soil layer and the precast concrete component; the soil layer has an enlarged head and a pile hole, the enlarged head is enclosed by the crushed stone layer and is located on the outer surface of the crushed stone layer, the pile hole is connected to the enlarged head and penetrates the soil layer, is located above the enlarged head and is close to the ground; the steel casing includes an outer tube, an inner tube and an outer expansion plate, the outer tube is slidably connected to the soil layer and is located in the pile hole, the inner tube is slidably connected to the outer tube and is slidably connected to the crushed stone layer The outer expansion plate is rotatably connected to the outer cylinder, slidably connected to the gravel, slidably connected to the inner cylinder, and is also located at the bottom of the outer cylinder, close to the gravel layer; the precast concrete assembly includes a precast pile and a pile body steel cage, the precast pile is engaged with the gravel layer and is located inside the outer cylinder, and the bottom is located in the gravel layer, the pile body steel cage is fixedly connected to the precast pile, and is located on the surface of the pile body, and is located inside the outer cylinder; the connection assembly includes a concrete cushion layer and a cast-in-place concrete layer, and is fixedly connected to the gravel layer, and is located in the enlarged head, and is also located on the surface of the gravel layer, the cast-in-place concrete layer is fixedly connected to the soil layer, and is fixedly connected to the concrete cushion layer, and is fixedly connected to the precast pile, and is also fixedly connected to the pile body steel cage, the cast-in-place concrete layer is located between the soil layer and the precast pile, and between the concrete cushion layer and the precast pile.

[0005] Wherein, the soil layer also has a sedimentation trough, the number of the sedimentation troughs is multiple, and they are respectively connected with the pile holes and located outside the pile body; the cast-in-place concrete layer fills the sedimentation trough.

[0006] Among them, the pile body steel cage includes pile body spiral dowels and bottom reserved dowels, the pile body spiral dowels are fixedly connected to the precast pile, located inside the precast pile, extending out of the surface of the precast pile, and spirally surrounding the surface of the precast pile; the bottom reserved dowels are fixedly connected to the precast pile and fixedly connected to the pile body spiral dowels, extending out of the bottom of the precast pile, extending toward the gravel layer, and located in the enlarged head.

[0007] Among them, the bottom reserved dowel bars include a first annular steel bar, a connecting steel bar and a second annular steel bar. The first annular steel bar is fixedly connected to the pile body spiral dowel bars, and is sleeved with the precast pile, and is located at the bottom of the precast pile, close to the gravel layer; the connecting steel bar is rotatably connected to the first annular steel bar, and is fixedly connected to the precast pile, and is located at the bottom of the precast pile, extending in a direction away from the precast pile, and the number of the connecting steel bars is multiple, and they are evenly arranged around the first annular steel bar; the second annular steel bar is fixedly connected to the plurality of connecting steel bars, and is located at the end of the connecting steel bar away from the first annular steel bar, and is located inside the enlarged head.

[0008] In which, the precast pile has a reserved hole, which is located at the bottom of the precast pile and extends into the interior of the precast pile, with the opening direction facing the interior of the enlarged head; the connecting assembly also includes positioning dowels and fixed dowels, the fixed dowels are fixedly connected to the gravel layer and the concrete cushion layer, and cooperate with the reserved hole, are also located inside the gravel layer, and extend in the direction away from the gravel layer, the positioning dowels are fixedly connected to the gravel layer and the concrete cushion layer, and there are multiple positioning dowels, which are respectively arranged in a ring around the fixed dowels.

[0009] Wherein, the rammed and expanded pile structure also includes a pile body bottom monitor and an external display, wherein the pile body bottom monitor is detachably connected to the precast pile and is located at the bottom of the precast pile, facing the fixed dowel bar; the external display is radio-connected to the pile body bottom monitor and is located above the pile body, away from the pile body bottom monitor.

[0010] Among them, the connecting assembly also includes soil layer support, pile body support and a threaded adjuster, the soil layer support is engaged with the soil layer, and is sleeved with the pile hole, and is located around the pile hole; the pile body support is sleeved with the prefabricated pile, and is located on the surface of the prefabricated pile, and is located inside the soil layer support; the threaded adjuster is fixedly connected to the soil layer support, and is fixedly connected to the pile body support, and is located between the soil layer support and the pile body support.

[0011] A rammed and expanded pile structure of the present invention is characterized in that the site is leveled and the lines are laid out before construction, the pile hole and the expanded head are dug, the gravel layer is placed, and preliminary tamping is performed, the outer cylinder is placed, and the cone formed by the plurality of outer expansion plates is inserted into the gravel layer and inserted to the designed depth, so that the inner cylinder resists the outer expansion plate, the outer expansion plate is further opened, and the surrounding gravel layer is rammed and expanded in the horizontal direction, the inner cylinder is taken out, the concrete cushion layer is poured in the outer cylinder, and the precast pile is placed in the pile hole, embedded in the gravel layer, and connected with the concrete cushion layer, and then the cast-in-place concrete layer is poured in layers into the outer cylinder, and the outer cylinder is lifted while pouring, and vibrated to make the precast pile better connected with the bottom expanded head and the side soil layer, so as to avoid the concrete segregation of the core bearing part and affect the bearing strength of the pile. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a schematic diagram of the steel casing of the present invention being inserted into a crushed stone layer.

[0014] Figure 2 It is a schematic diagram of fixing the prefabricated piles of the present invention.

[0015] Figure 3 It is a connection schematic diagram of the prefabricated piles of the present invention.

[0016] Figure 4 It is a schematic diagram of the bottom connection of the prefabricated pile of the present invention.

[0017] In the figure: 1-soil layer, 2-gravel layer, 3-steel casing, 4-precast concrete component, 5-connection component, 6-pile bottom monitor, 7-external display, 11-enlarged head, 12-pile hole, 13-sedimentation trough, 31-outer tube, 32-inner tube, 33-outer expansion plate, 41-precast pile, 42-pile body steel cage, 51-concrete cushion, 52-cast-in-place concrete layer, 53-positioning dowel bar, 54-fixed dowel bar, 55-soil layer support, 56-pile body support, 57-thread adjuster, 100-rammed and expanded pile structure, 411-reserved hole, 422-bottom reserved dowel bar, 4221-first ring steel bar, 4222-connecting steel bar, 4223-second ring steel bar. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0020] See also Figure 1 , Figure 2 and Figure 3The present invention provides a rammed-and-expanded pile structure 100, comprising a soil layer 1, a gravel layer 2, a steel casing 3, a precast concrete component 4 and a connection component 5, wherein the gravel layer 2 is fixedly connected to the soil layer 1 and is located inside the soil layer 1, the steel casing 3 is slidably connected to the soil layer 1 and is engaged with the gravel layer 2, the precast concrete component 4 is slidably connected to the steel casing 3 and is located inside the steel casing 3, the connection component 5 is fixedly connected to the precast concrete component 4 and is fixedly connected to the soil layer 1 and is located between the soil layer 1 and the precast concrete component 4. The soil layer 1 has an enlarged head 11 and a pile hole 12, the enlarged head 11 is enclosed with the gravel layer 2 and is located on the outer surface of the gravel layer 2, the pile hole 12 is connected with the enlarged head 11, and passes through the soil layer 1, is located above the enlarged head 11, and is close to the ground; the steel casing 3 includes an outer tube 31, an inner tube 32 and an outer expansion plate 33, the outer tube 31 is slidably connected with the soil layer 1 and is located in the pile hole 12, the inner tube 32 is slidably connected with the outer tube 31, and is slidably connected with the gravel layer 2, and The outer expansion plate 33 is located inside the outer cylinder 31, and is rotatably connected to the outer cylinder 31, and is slidably connected to the crushed stone, and is slidably connected to the inner cylinder 32, and is also located at the bottom of the outer cylinder 31, close to the crushed stone layer 2; the precast concrete assembly 4 includes a precast pile 41 and a pile body steel cage 42, the precast pile 41 is engaged with the crushed stone layer 2, and is located inside the outer cylinder 31, and the bottom is located in the crushed stone layer 2, the pile body steel cage 42 is fixedly connected to the precast pile 41, and is located on the pile body surface, and is located in the outer cylinder 3 1; the connecting assembly 5 includes a concrete cushion layer 51 and a cast-in-place concrete layer 52, and is fixedly connected to the gravel layer 2, and is located in the enlarged head 11, and is also located on the surface of the gravel layer 2, the cast-in-place concrete layer 52 is fixedly connected to the soil layer 1, and is fixedly connected to the concrete cushion layer 51, and is fixedly connected to the precast pile 41, and is also fixedly connected to the pile body steel cage 42, the cast-in-place concrete layer 52 is located between the soil layer 1 and the precast pile 41, and is located between the concrete cushion layer 51 and the precast pile 41.

[0021] In this embodiment, the soil layer 1 is silt, sand, gravel soil and plastic or hard plastic clay. The soil layer 1 is leveled and compacted before construction. The pile hole 12 is a cylindrical hole with a center line perpendicular to the horizontal plane and extending into the soil layer 1. The enlarged head 11 is connected to the pile hole 12 and is located inside the soil layer 1 away from the ground. The cross-sectional area of ​​the enlarged head 11 is larger than the cross-sectional area of ​​the pile hole 12. The gravel layer 2 is located at the bottom of the enlarged head 11 and has a thickness of not less than 2 meters. The outer cylinder 31 is cylindrical with an outer diameter the same as the aperture of the pile hole 12, is located in the pile hole 12, and resists the surrounding soil layer 1. There are multiple outer expansion plates 33, which are rotated with the bottom of the outer cylinder 31. The outer expansion plates 33 are enclosed to form a cone, and a hole is left in the middle for the fixed steel bar to pass through. The outer cylinder 31 extends into the gravel layer 2 through the outer expansion plates 33. The inner cylinder 32 is fitted with the outer cylinder 31 and slides in the outer cylinder 31. The inner cylinder 32 contacts the outer expansion plates 33 and continues to slide toward the gravel layer 2, so that the outer expansion plates 33 move away from the center line of the outer cylinder 31, so that the inner cylinder 32 can enter the gravel layer 2 and push the outer expansion plates 33 to squeeze the gravel layer 2, so that the gravel layer 2 is more tightly connected in the horizontal direction. The precast pile 41 is a precast concrete pile with a concrete grade not lower than C30, and the surface has the precast steel bar The prefabricated steel cage is a spiral steel cage, and the steel bars are threaded steel bars with a diameter of 16 mm. The prefabricated pile 41 is surrounded by the prefabricated pile 41, and extends into the prefabricated pile 41, and is connected to the concrete. The concrete cushion layer 51 is a fine stone concrete cushion layer 51, which is laid on the surface of the crushed stone layer 2 to fill the gap between the concrete cushion layer 51 and the crushed stone layer 2. The cast-in-place concrete layer 52 is located between the prefabricated pile 41 and the concrete cushion layer 51, and is located around the prefabricated pile 41, connected to the pile body steel cage 42, and connected to the soil layer 1. In this way, the site is leveled and the line is laid out before construction, the pile hole 12 and the enlarged head 11 are dug, the crushed stone layer 2 is placed, and preliminary compaction is performed, and the outer cylinder is placed. 31, insert the cone formed by the plurality of outer expansion plates 33 into the gravel layer 2 and insert it to the designed depth, make the inner tube 32 resist the outer expansion plate 33, make the outer expansion plate 33 further open, and expand the surrounding gravel layer 2 in the horizontal direction, take out the inner tube 32, pour the concrete cushion layer 51 in the outer tube 31, put the precast pile 41 into the pile hole 12, embed it into the gravel layer 2, and connect it with the concrete cushion layer 51, and then pour the cast-in-place concrete layer 52 into the outer tube 31 in layers, lift the outer tube 31 while pouring, and vibrate it, so that the precast pile 41 has better connectivity with the bottom enlarged head 11 and the side soil layer 1, and avoid concrete segregation in the core bearing part,Affects the bearing strength of the pile.

[0022] Furthermore, the soil layer 1 also has a settling trough 13 . There are multiple settling troughs 13 , which are respectively connected to the pile holes 12 and are located outside the pile body. The cast-in-place concrete layer 52 fills the settling troughs 13 .

[0023] In this embodiment, the pile hole 12 is a cylindrical pile hole 12, the settlement tank 13 is connected with the pile hole 12, and is embedded in the soil layer 1 in a direction perpendicular to the center line of the pile hole 12, so that the pile hole 12 has a plurality of cavities protruding outward, and after the precast pile 41 is placed, the cast-in-place concrete is poured into the pile hole 12, and the cast-in-place concrete fills the pile hole 12 and the settlement tank 13, so that the connector between the cast-in-place concrete and the precast pile 41 is engaged with the soil layer 1, thereby increasing the friction between the cast-in-place concrete and the soil layer 1, making it difficult for the precast pile 41 to settle, thereby avoiding cracks in the concrete during the settlement process, which affects the bearing strength of the pile.

[0024] Furthermore, the pile body steel cage 42 includes pile body spiral dowels and bottom reserved dowels 422, the pile body spiral dowels are fixedly connected to the precast pile 41, are located inside the precast pile 41, extend out of the surface of the precast pile 41, and spirally surround the surface of the precast pile 41; the bottom reserved dowels 422 are fixedly connected to the precast pile 41, and are fixedly connected to the pile body spiral dowels, extend out of the bottom of the precast pile 41, extend toward the gravel layer 2, and are also located in the enlarged head 11.

[0025] In this embodiment, the spiral dowel bars of the pile body have connecting bars located inside the precast pile 41 and spiral steel bars located outside and spirally surrounding the precast pile 41. The spiral dowel bars of the pile body are fixed by multiple connecting bars and connected to the cast-in-place concrete. The bottom reserved dowel bars 422 are tied and overlapped with the spiral dowel bars of the pile body, and are connected to the pile body through connecting bars extending into the bottom of the pile body, and are connected to the cast-in-place concrete, so that the connectivity between the cast-in-place concrete and the precast pile 41 is better, avoiding cracks in the cast-in-place concrete and separation from the precast pile 41, affecting the connection between the precast pile 41 and the soil layer 1 and the gravel layer 2, and further affecting the bearing strength of the pile.

[0026] Furthermore, the bottom reserved dowel bars 422 include a first annular steel bar 4221, a connecting steel bar 4222 and a second annular steel bar 4223, the first annular steel bar 4221 is fixedly connected to the pile body spiral dowel bars, and is fitted with the precast pile 41, and is located at the bottom of the precast pile 41, close to the gravel layer 2; the connecting steel bar 4222 is rotatably connected to the first annular steel bar 4221, and is fixedly connected to the precast pile 41, and is located at the bottom of the precast pile 41, extending in a direction away from the precast pile 41, and the number of the connecting steel bars 4222 is multiple, and is evenly arranged around the first annular steel bar 4221; the second annular steel bar 4223 is fixedly connected to the multiple connecting steel bars 4222, and is located at the end of the connecting steel bar 4222 away from the first annular steel bar 4221, and is located inside the enlarged head 11.

[0027] In this embodiment, the first annular steel bar 4221 is welded to the pile body spiral dowel bar and is fitted with the precast pile 41 and is located at the bottom of the precast pile 41. The number of the connecting steel bars 4222 is multiple and they are respectively tied and overlapped with the first annular steel bar 4221. The second annular steel bar 4223 is connected to the first annular steel bar 4221 through the connecting steel bars 4222. The second annular steel bar 4223 is formed by tying and overlapping a plurality of arcuate steel bars, and the overlapping portion is not less than the general length of the arcuate steel bars, so that the plurality of arcuate steel bars can slide in the arc direction, so that the diameter of the second annular steel bar 4223 can be increased, and then the second annular steel bar 4223 and the connecting bars extend in the horizontal direction and are connected with the cast-in-place concrete located in the enlarged head 11, so as to enhance the shear strength of the cast-in-place concrete in the enlarged head 11, and avoid the cast-in-place concrete in the enlarged head 11 from breaking when the precast pile 41 transmits force to the bottom, thereby affecting the bearing capacity of the precast pile 41.

[0028] Furthermore, the precast pile 41 has a reserved hole 411, which is located at the bottom of the precast pile 41 and extends into the interior of the precast pile 41, with the opening direction facing the interior of the enlarged head 11; the connecting component 5 also includes a positioning dowel 53 and a fixing dowel 54, the fixing dowel 54 is fixedly connected to the gravel layer 2 and the concrete cushion layer 51, and cooperates with the reserved hole 411, is also located inside the gravel layer 2, and extends in a direction away from the gravel layer 2, the positioning dowel 53 is fixedly connected to the gravel layer 2 and the concrete cushion layer 51, and there are multiple positioning dowels, which are respectively arranged in a ring around the fixing dowel 54.

[0029] In this embodiment, the reserved hole 411 is located at the bottom of the precast pile 41 and at the center of the cross section of the precast pile 41. The positioning dowel bar 53 is determined by construction layout. The four relative points on the outside of the precast pile 41 are laid out and positioned by an instrument, and the fixed dowel bar 54 is laid out and positioned, located at the center of the four external points and matched with the reserved hole 411. In this way, the precast pile 41 can be accurately fixed, and the bearing capacity calculation performed before construction can be accurately executed, avoiding the bearing capacity of the precast pile 41 being affected by positioning deviation.

[0030] Furthermore, the rammed and expanded pile structure 100 also includes a pile body bottom monitor 6 and an external display 7. The pile body bottom monitor 6 is detachably connected to the precast pile 41 and is located at the bottom of the precast pile 41, facing the fixed dowel 54; the external display 7 is radio-connected to the pile body bottom monitor 6 and is located above the pile body, away from the pile body bottom monitor 6.

[0031] In this embodiment, the bottom monitor is connected to the precast pile 41 and is connected to the ground personnel through a rope. The rope pulls the bottom monitor to separate the bottom monitor from the precast pile 41 and recover it. The bottom monitor has a camera to take real-time photos of the bottom of the precast pile 41 and the fixed steel bars, and transmit the photos to the external display 7 by radio signals. The ground operator observes the external display 7 and adjusts the installation position of the precast pile 41. When the front end of the fixed dowel 54 fits into the reserved hole 411, the ground personnel pulls the rope to remove the bottom monitor and recover it. In this way, the precast pile 41 can be accurately installed, and the bearing capacity calculation performed before construction can be accurately executed, avoiding the bearing capacity of the precast pile 41 being affected by positioning deviation.

[0032] For further information, see Figure 4 The connection assembly 5 also includes a soil layer support 55, a pile body support 56 and a threaded adjuster 57. The soil layer support 55 is engaged with the soil layer 1, and is sleeved with the pile hole 12, and is located around the pile hole 12; the pile body support 56 is sleeved with the prefabricated pile 41, and is located on the surface of the prefabricated pile 41, and is located inside the soil layer support 55; the threaded adjuster 57 is fixedly connected to the soil layer support 55, and is fixedly connected to the pile body support 56, and is located between the soil layer support 55 and the pile body support 56.

[0033] In this embodiment, the soil layer support 55 is an annular steel cylinder, and its outer diameter is the same as the diameter of the pile hole 12, which supports the surrounding soil layer 1. The pile body support 56 is also an annular steel cylinder, and is fitted with the bottom of the precast pile 41. The threaded adjuster 57 is located between the soil layer support 55 and the pile body support 56. By adjusting the connecting rod of the threaded adjuster 57, the distance between the soil layer support 55 and the pile body support 56 is changed. The two threaded adjusters 57 are located in two directions perpendicular to each other, and the top of the precast pile 41 is adjusted in multiple directions, so that the bearing capacity calculation performed before construction can be accurately executed, avoiding the bearing capacity of the precast pile 41 being affected by positioning deviation.

[0034] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A rammed-and-expanded pile structure, characterized in that: It comprises a soil layer, a gravel layer, a steel casing, a precast concrete component and a connection component, wherein the gravel layer is fixedly connected to the soil layer and is located inside the soil layer, the steel casing is slidably connected to the soil layer and is engaged with the gravel layer, the precast concrete component is slidably connected to the steel casing and is located inside the steel casing, and the connection component is fixedly connected to the precast concrete component and to the soil layer, and is located between the soil layer and the precast concrete component; The soil layer has an enlarged head and a pile hole, the enlarged head is enclosed with the gravel layer and is located on the outer surface of the gravel layer, the pile hole is connected with the enlarged head and penetrates the soil layer, and is located above the enlarged head and close to the ground; The steel casing comprises an outer tube, an inner tube and an outer expansion plate, the outer tube is slidably connected to the soil layer and is located in the pile hole, the inner tube is slidably connected to the outer tube and is slidably connected to the gravel layer and is located inside the outer tube, the outer expansion plate is rotatably connected to the outer tube and is slidably connected to the gravel layer and is slidably connected to the inner tube, and is located at the bottom of the outer tube, close to the gravel layer; The precast concrete assembly includes a precast pile and a pile body steel cage, wherein the precast pile is engaged with the gravel layer and is located inside the outer tube, and the bottom is located inside the gravel layer, and the pile body steel cage is fixedly connected to the precast pile and is located on the surface of the precast pile body and inside the outer tube; The connection assembly includes a concrete cushion layer and a cast-in-place concrete layer, and is fixedly connected to the gravel layer, and is located in the enlarged head and also located on the surface of the gravel layer. The cast-in-place concrete layer is fixedly connected to the soil layer, and is fixedly connected to the concrete cushion layer, and is fixedly connected to the precast piles, and is also fixedly connected to the pile body reinforcement cage. The cast-in-place concrete layer is located between the soil layer and the precast piles, and between the concrete cushion layer and the precast piles. The site is leveled and positioned before construction, the pile hole and the enlarged head are dug, the crushed stone layer is placed, and preliminary compaction is performed, the outer cylinder is placed, and the cone formed by the plurality of outer expansion plates is inserted into the crushed stone layer and inserted to the designed depth, so that the inner cylinder and the outer expansion plate resist each other, the outer expansion plate is further opened, and the surrounding crushed stone layer is compacted and expanded in the horizontal direction, the inner cylinder is taken out, the concrete cushion layer is poured in the outer cylinder, and the prefabricated pile is placed in the pile hole, embedded in the crushed stone layer, and connected with the concrete cushion layer, and then the cast-in-place concrete layer is poured into the outer cylinder in layers, and the outer cylinder is lifted while pouring; The pile body reinforcement cage includes a pile body spiral dowel and a bottom reserved dowel. The pile body spiral dowel is fixedly connected to the precast pile, is located inside the precast pile, extends out of the surface of the precast pile, and spirally surrounds the surface of the precast pile; the bottom reserved dowel is fixedly connected to the precast pile and is fixedly connected to the pile body spiral dowel, extends out of the bottom of the precast pile, extends toward the gravel layer, and is located in the enlarged head; The connection assembly also includes a soil layer support, a pile body support and a threaded adjuster. The soil layer support is engaged with the soil layer, and is sleeved with the pile hole, and is located around the pile hole; the pile body support is sleeved with the prefabricated pile, and is located on the surface of the prefabricated pile, and is located inside the soil layer support; the threaded adjuster is fixedly connected to the soil layer support, and is fixedly connected to the pile body support, and is located between the soil layer support and the pile body support.

2. The rammed-and-expanded pile structure according to claim 1, characterized in that: The soil layer also has a plurality of sedimentation troughs, which are respectively connected with the pile holes and located outside the pile body; the cast-in-place concrete layer fills the sedimentation troughs.

3. The rammed-and-expanded pile structure according to claim 1, characterized in that: The bottom reserved dowel bars include a first annular steel bar, a connecting steel bar and a second annular steel bar. The first annular steel bar is fixedly connected to the pile body spiral dowel bars, is sleeved with the precast pile, and is located at the bottom of the precast pile, close to the gravel layer; the connecting steel bar is rotatably connected to the first annular steel bar, is fixedly connected to the precast pile, is located at the bottom of the precast pile, and extends in a direction away from the precast pile. There are multiple connecting steel bars, which are evenly arranged around the first annular steel bar; the second annular steel bar is fixedly connected to the multiple connecting steel bars, and is located at the end of the connecting steel bar away from the first annular steel bar, and is located inside the enlarged head.

4. The rammed-and-expanded pile structure according to claim 1, characterized in that: The precast pile has a reserved hole, which is located at the bottom of the precast pile and extends into the interior of the precast pile, with the opening direction facing the interior of the enlarged head; the connection assembly also includes positioning dowels and fixed dowels, the fixed dowels are fixedly connected to the gravel layer and the concrete cushion layer, and cooperate with the reserved hole, are also located inside the gravel layer, and extend in a direction away from the gravel layer, the positioning dowels are fixedly connected to the gravel layer and the concrete cushion layer, and there are multiple positioning dowels, which are respectively arranged in a ring around the fixed dowels.

5. The rammed-and-expanded pile structure according to claim 4, characterized in that: The rammed-and-expanded pile structure also includes a pile body bottom monitor and an external display. The pile body bottom monitor is detachably connected to the precast pile and is located at the bottom of the precast pile, facing the fixed dowel bar; the external display is radio-connected to the pile body bottom monitor and is located above the pile body, away from the pile body bottom monitor.

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