CN115726347A

CN115726347A - Pipe pile extension, bottom expanding and diameter expanding integrated device and construction method

Info

Publication number: CN115726347A
Application number: CN202211370523.6A
Authority: CN
Inventors: 王磊; 匡昕昕; 徐小巍; 陆文哲; 朱黎炜
Original assignee: Zhejiang Urban & Rural Planning Design Institute
Current assignee: Zhejiang Urban & Rural Planning Design Institute
Priority date: 2022-11-03
Filing date: 2022-11-03
Publication date: 2023-03-03

Abstract

The invention discloses a pipe pile splicing, bottom expanding and diameter expanding integrated device and a construction method, and belongs to the field of building construction. In the integrated device, a plurality of sections of pipe piles are connected through an expanding joint and a pipe pile joint and then are driven into a soil layer, the expanding joint is sequentially expanded by using an underreamer to form expanding, then a grouting machine is connected with a bag type bottom expanding device through a grouting pipe, and a certain amount of grout is injected and then is solidified to form a bottom expanding. The invention can improve the side resistance and end resistance of pile, improve the bearing capacity of pile foundation, especially the resistance to pulling, mainly the side friction resistance, so it can reduce the length and number of pile, and reduce the cost.

Description

Pipe pile extension, bottom expanding and diameter expanding integrated device and construction method

Technical Field

The invention relates to the field of building foundation construction, in particular to a tubular pile splicing, bottom expanding and diameter expanding integrated device and a construction method.

Background

The bearing capacity of the pile foundation is composed of the side mold resistance of the pile body and the soil around the pile and the end bearing capacity of the pile end on the bearing layer, generally speaking, the bearing capacity of the pile foundation can be improved by a method of increasing the length and the diameter of the pile, but the effect of improving the bearing capacity of the pile foundation by the method is not high, so that a bottom expanding method and a diameter expanding method are invented to improve the bearing capacity of the pile foundation, and the method is widely applied to cast-in-place piles.

For example, in patent application No. CN201310056968.1, a dynamic compaction vibration composite bottom-expanding pile machine and a dynamic compaction vibration composite bottom-expanding pile construction method are provided, which perform end dynamic compaction bottom-expanding by filling a dynamic compaction auxiliary material, and form an expanded head by pouring concrete and dynamic compaction. The pedestal pile can improve the bearing capacity of a single pile. In addition, in the utility model patent of application No. CN201320162595.1, a reducing pedestal pile foundation is provided, the downside of its pile body is equipped with the pile wing, the extending direction of the pile wing is mutually perpendicular with the axis of the pile body, the pile wing outwards is spoke-shaped from the axis of the pile body and sets up around the pile body, the pile wing is equiangular distribution between each wing on the same horizontal cross section of the pile body, the wing is triangle-shaped along the vertical upper portion of the pile body, the pedestal pile end upper portion and lower portion are the frustum. Theoretically, the bearing capacity of the pile foundation can be further improved by the variable-diameter pedestal pile foundation.

However, such pedestal or expanding pile foundation often needs to be constructed on site, which is not efficient and difficult to ensure construction quality. With the popularization of precast tubular piles, a method of combining a bottom-expanding or diameter-expanding structure to the precast tubular pile has gradually appeared. For example, the invention patent with the application number of CN201710221108.7 provides a prefabricated club-footed reducing pile for treating soft soil foundation and a construction method thereof, and the utility model patent with the application number of CN201721065866.6 discloses an expanding cement mixing pile-prefabricated pile foundation. However, in the construction of the precast tubular piles, the precast piles are driven into the soil layer by static force or dynamic force, and because the pile end resistance of the bottom-expanding tubular pile and the pile side resistance of the expanding tubular pile are too large, the construction difficulty in the pile pressing process is greatly increased, and the development of the precast bottom-expanding tubular pile and the expanding tubular pile is always limited.

Therefore, how to realize the bottom expanding and the diameter expanding of the precast tubular pile and reduce the construction difficulty in the pile pressing process is a technical problem to be solved urgently at present.

Disclosure of Invention

The invention provides a pile extension, bottom expansion and diameter expansion integrated device and a construction method for a tubular pile, aiming at various problems of a bottom expansion tubular pile and a diameter expansion tubular pile in the background technology, and reducing the difficulty of the construction process of the bottom expansion and diameter expansion tubular pile.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a pipe pile splicing, bottom expanding and diameter expanding integrated device which comprises a pipe pile, a diameter expanding joint, a pipe pile joint, an underreamer, a pile tip connecting hoop, a bag type bottom expanding device and a pile tip, wherein the diameter expanding joint is arranged on the inner wall of the pipe pile;

the multiple sections of tubular piles are sequentially spliced vertically to form a pile body; the splicing end surfaces of any two sections of adjacent tubular piles are respectively fixed with a tubular pile joint, and the two tubular pile joints are clamped and fixed through expanding joints, so that the two sections of adjacent tubular piles form reliable connection; the diameter-expanding joint is internally provided with a diameter-variable mechanism which can radially extend and retract along the cross section of the pile body, and the diameter-variable mechanism has a contraction state of completely contracting in the pile body and an diameter-expanding state of extending out of the pile body;

the reamer is used for applying a driving force along the radial direction of the cross section of the pile body to the diameter-variable mechanism, so that the diameter-variable mechanism is converted into a diameter-expanded state from a contracted state;

a section of pipe pile positioned at the bottommost end in the pile body is arranged on the pile tip through a pile tip connecting hoop; the bag type bottom expanding device is arranged above the pile tip and is provided with a grouting port;

the grouting opening is used for being connected with an external grouting machine through a grouting pipe, so that grout is pressed into an expandable bag of the bag type bottom expanding device, the pile tip is pushed to be separated from the bag type bottom expanding device after the expandable bag is grouted and expanded, and the peripheral soil body of the pile bottom is further squeezed and expanded by the bag to form a pile end expanding head.

Preferably, in the first aspect, the expanding joint includes an upper end plate, a lower end plate, a connecting rib plate, an expanding blade, and a connecting bolt; the upper end plate and the lower end plate are arranged in parallel at intervals, and a connecting structure capable of bearing the load in the direction vertical to the end plates is formed between the upper end plate and the lower end plate by clamping and fixing a plurality of connecting rib plates; the diameter-expanding blades and the connecting rib plates are assembled in a one-to-one correspondence mode, each diameter-expanding blade comprises a fan-shaped annular plate and an arc limiting plate, a slide way penetrating through the plate body is formed in the fan-shaped annular plate, the fan-shaped annular plate is installed between the upper end plate and the lower end plate and is sleeved outside the connecting rib plates through the slide way, so that a sliding pair limiting the fan-shaped annular plate to move along the radial direction is formed, the size of the arc limiting plate is larger than the gap between the upper end plate and the lower end plate, and the arc limiting plate can be limited to move outwards continuously when moving outwards to the limiting position; and the outward surfaces of the upper end plate and the lower end plate are respectively provided with a connecting piece for connecting a tubular pile joint.

As a preferred aspect of the first aspect, the tubular pile joint includes an end plate and an end plate hole, and the end plate is fixed on the splicing end face of the tubular pile; the end plate holes are uniformly arranged along the circumference of the end plate, the number and the positions of the end plate holes are the same as the number of the connecting pieces on the expanding joint, and the connecting pieces can be matched and fixed in the end plate holes.

Preferably, in the first aspect, the connecting members on the upper end plate and the lower end plate are connecting bolts, the threaded sections of the connecting bolts are fixed on the end plates, and the bolt heads of the connecting bolts are spaced from the surface of the end plates; the end plate hole on the end plate adopts the reducing hole, have the first hole district and the second hole district of intercommunication in the reducing hole, wherein the hole size in first hole district can supply the bolt head stretches into, and the bolt head can move to the second hole district from first hole district, but the hole size in second hole district can't make the bolt head directly break away from the second hole district.

Preferably, as for the first aspect, the reamer comprises a drive mechanism and a plurality of sets of cross arms and reamer end plates; in each group of cross arms and reaming end plates, the reaming end plates are connected with the driving mechanism through the cross arms; under the drive of the driving mechanism, all the reaming end plates synchronously stretch and retract to form a gathering state and an expanding state; in the gathering state, the gathered sizes of all the reaming end plates can integrally extend into the enclosed space of the arc limiting plates of all the expanding blades in the contraction state; in an expansion state, the expanded sizes of all the expanding end plates can enable all the expanded blades to prop up the arc limiting plates in the inner rings of the upper end plate and the lower end plate after being expanded.

As a preferable aspect of the first aspect, the pile tip connecting hoop is composed of a first annular section, a second annular section, a top surface for closing the top of the first annular section, and a step surface for connecting the two annular sections, and the whole body is in a convex shape with an open bottom; the outer diameter of the first annular section is consistent with the inner diameter of the tubular pile, and the outer diameter of the second annular section is consistent with the outer diameter of the tubular pile; in an assembly state, a tubular pile joint at the end part of the tubular pile is supported on the step surface, the first annular section extends into the inner cavity of the tubular pile, the second annular section can be detachably buckled on the pile tip, and the top surface, the first annular section and the top surface of the pile tip are enclosed to form an accommodating space; the bag type bottom expanding device comprises an expandable bag and a bag connector; the inflatable bladder is disposed in the receiving space; the bag joint extends out of the pile tip connecting hoop through a through hole formed in the top surface and is used for injecting grouting liquid into the expandable bag.

Preferably, the end of the outlet end of the grouting pipe is a magnetic joint capable of connecting with the bag joint in a self-locking manner.

As the optimization of the first aspect, the device further comprises a centering device for keeping the pipe extending into the pipe pile to be centered all the time; the ware placed in the middle includes sleeve pipe and three piece at least telescopic links, the sleeve pipe is used for the ring cover to fix on stretching into the pipeline in the tubular pile, and on angle vertical fixation such as all telescopic links hoop was in the sleeve pipe, the telescopic link can carry out synchronous flexible according to tubular pile internal diameter size, makes the pipeline that sleeve pipe and inside penetrated reciprocates the in-process all the time between two parties in the tubular pile.

In a second aspect, the invention provides a pipe pile extension, bottom expanding and diameter expanding construction method using the integrated device in any one of the first aspects, which comprises the following steps:

s1, determining a pile position coordinate according to a design drawing, and placing a pile tip on the ground of a coordinate point; installing the bag type bottom expanding device in the pile tip connecting hoop, keeping the bag joint to extend out of the pile tip connecting hoop through a through hole formed in the top surface, and then buckling and fixing the pile tip connecting hoop of the installed bag type bottom expanding device on the pile tip; respectively fixing a pipe pile joint on the splicing end faces of all the pipe piles to be connected;

s2, vertically assembling the first section of tubular pile on the pile tip connecting hoop, and inserting the first annular section at the upper part of the pile tip connecting hoop into the tubular pile; then, driving the first section of tubular pile into a soil layer by using pile driving equipment, and only keeping the top part of the pile exposed out of the ground;

s3, placing an expanding joint on the tubular pile joint of the tubular pile top exposed out of the ground, adjusting the position to enable connecting bolt heads on the lower end plate to correspondingly extend into a first hole area of a tubular pile joint end plate hole one by one, and then rotating the expanding joint to enable all the connecting bolt heads to move from the first hole area to a second hole area to complete the connection of the expanding joint and the tubular pile below; placing the other section of tubular pile on an upper end plate of the expanding joint, adjusting the position to enable connecting bolt heads on the upper end plate to correspondingly extend into a first hole area of an end plate hole of the tubular pile joint one by one, and then rotating the upper tubular pile to enable all the connecting bolt heads to move from the first hole area to a second hole area so as to complete the connection of the expanding joint and the upper tubular pile; after the upper and lower sections of tubular piles are connected and fixed, the pile is continuously pressed downwards, so that the upper tubular pile is driven into a soil layer and only the pile top part is left to be exposed out of the ground;

s4, continuously repeating the step S3 until all the tubular piles are driven into the soil layer;

s5, after all tubular piles are driven into a soil layer, lowering the reamers with all reaming end plates in a gathering state to a first diameter-expanding joint position, starting a driving mechanism, enabling all the reaming end plates to synchronously extend outwards to an expanding state, enabling all the reaming end plates to respectively push corresponding diameter-expanding blades to move outwards in the expanding process, and enabling all the diameter-expanding blades in the first diameter-expanding joint to synchronously extend out of a pile body to form a diameter-expanding structure for improving the bearing capacity of a pile foundation; then all the reaming end plates are contracted again to a gathering state, and then are put down to the position of the next diameter expanding joint and are changed into a diameter expanding state; continuously repeating the steps until all the expanding joints are changed into an expanding state, and taking out the reamer;

s5, sleeving a sleeve of the centering device on a grouting pipe connected with a grouting machine, and adjusting the length of telescopic rods according to the inner diameter of the tubular pile to enable the length of all the telescopic rods to be equal to the difference between the inner radius of the tubular pile and the outer radius of the sleeve; and then, a grouting pipe with a centering device is lowered to the pile bottom to be connected with the bag joint, a grouting machine is started to pressurize and inject grouting slurry into the expandable bag, the expandable bag is expanded under the action of grouting pressure to push the pile tip to be separated from the pile tip connecting hoop, the pile bottom is continuously extended, a peripheral soil body is squeezed and expanded, the centering device and the grouting pipe are pulled out after grouting is finished, and a pile end expanded head for improving the bearing capacity of the pile bottom is formed after cement slurry is solidified.

Preferably, in the first aspect, the maximum expanded diameter of the expandable bladder is 1.5 to 2 times the outer diameter of the tubular pile.

Preferably, in the first aspect, the grouting pressure of the grouting machine is 0.5 to 2MPa.

Preferably, the grouting liquid is cement paste or fine aggregate concrete, the grouting amount and the grouting pressure are controlled in a double mode, and grouting can be stopped when any one of the grouting liquid and the fine aggregate concrete meets the design requirement.

Compared with the prior art, the invention has the following beneficial effects:

1) The invention can improve the side resistance and end resistance of pile, and improve the bearing capacity of pile foundation, especially the anti-pulling bearing capacity mainly based on the side friction resistance of pile, so it can reduce the length and number of pile, and reduce the cost of project.

2) The bottom expanding and the diameter expanding adopted by the invention do not change the diameter of the pile body of the tubular pile, can adopt the traditional tubular pile production process and is easy to popularize. In addition, the diameter of the pile body is consistent up and down during the construction of the tubular pile, so that the pile driving difficulty is not increased, and the site construction is convenient.

3) The expanding joint adopts the currently widely used rotary anchoring method, is connected with the tubular pile end plate through rotation and anchoring, does not need to change the existing tubular pile connecting process, and has good universality and convenient construction.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural view of a pipe pile extension, bottom expansion and diameter expansion integrated device;

fig. 2 is a three-dimensional schematic view of the expanded joint in a contracted state.

Fig. 3 is a schematic plan view of the expanded diameter joint in a contracted state.

Fig. 4 is a schematic cross-sectional view of the expanded joint in a contracted state.

Fig. 5 is a three-dimensional schematic view of an expanding blade.

Fig. 6 is a schematic plan view of the expanded joint in an expanded state.

Fig. 7 is a three-dimensional schematic view of the expanded joint in an expanded state.

Fig. 8 is a plan view schematically showing a pipe pile joint.

Fig. 9 is a schematic view of the underreamer in a retracted state.

Fig. 10 is a schematic view of the underreamer in a deployed state.

Fig. 11 is a schematic view of the underreamer in a retracted state within the tubular pile.

Fig. 12 is a schematic view showing a state where the reamer is deployed in the tubular pile.

FIG. 13 is a longitudinal cross-sectional view of the stake point connector ferrule.

Fig. 14 is a plan view of the post tip connection ferrule and the post tip in a re-assembled state.

Fig. 15 is a partially enlarged view of a tubular pile bag type pedestal pile tip.

Fig. 16 is a three-dimensional schematic of a centralizer.

Fig. 17 is a schematic view of a part of the construction state of the pipe pile extension, bottom expanding and diameter expanding integrated device.

The reference numbers in the figures are: the tubular pile comprises a tubular pile 1, an expanding joint 2, an upper end plate 201, a lower end plate 202, a connecting rib plate 203, an expanding blade 204, a connecting bolt 205, a tubular pile joint 3, an end plate 301, an end plate hole 302, an underreamer 4, a hydraulic oil cylinder 401, a hydraulic piston rod 402, a first hydraulic pipe 403, a second hydraulic pipe 404, a cross arm 405, a stopper 406, a pin shaft 407, a fixed end block 408, a sliding end block 409, a reaming end plate 410, a pile tip connecting hoop 5, a top surface 501, a first annular section 502, a step surface 503, a second annular section 504, a bag type bottom expanding device 6, an expandable bag 601, a bag joint 602, grouting liquid 603, a grouting pipe 7, a pile tip 8, a pile tip plate 801, a bottom sealing 802, a pile tip chamfer 803, a centering device 9, a sleeve 901, a telescopic rod 902 and a grouting machine 10.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will recognize without departing from the spirit and scope of the present invention. The technical characteristics in the embodiments of the invention can be correspondingly combined on the premise of no mutual conflict.

In the description of the present invention, it should be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element, i.e., intervening elements may be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.

In the description of the present invention, it is to be understood that the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature.

In a preferred embodiment of the invention, as shown in fig. 1, a tubular pile base expanding and diameter expanding integrated device is provided, wherein a core component comprises a tubular pile 1, a diameter expanding joint 2, a tubular pile joint 3, a reamer 4, a pile tip connecting hoop 5, a bag type base expanding device 6 and a pile tip 8. In the integrated device, a plurality of sections of tubular piles 1 are connected through an expanding joint 2 and a tubular pile joint 3 and then are driven into a soil layer, the expanding joint 2 is sequentially expanded by a reamer 4 to form expanding, then a grouting machine 10 is connected with a bag type bottom expanding device 6 through a grouting pipe 7, and a certain amount of grout is injected and then is solidified to form a bottom expanding. The specific structure and the connection and cooperation relationship between the components are described in detail below.

In the prefabricated pile body structure, the pile body is formed by sequentially splicing a plurality of sections of pipe piles 1 prefabricated in a factory along the vertical direction. The length of the whole pile body can be adjusted by combining different numbers of tubular piles 1. For convenience of description, the end face of one tubular pile 1 which needs to be spliced with another tubular pile 1 or the pile tip 8 is referred to as a splicing end face in the invention.

In order to ensure that two sections of tubular piles 1 can be conveniently and reliably connected, tubular pile connectors 3 are respectively fixed on the splicing end faces of any two sections of adjacent tubular piles 1, and the tubular pile connectors 3 on the two splicing end faces are clamped and fixed through expanding connectors 2, so that the two sections of adjacent tubular piles 1 are reliably connected. Meanwhile, in order to form a corresponding expanding structure, the invention is provided with a diameter-variable mechanism which can stretch and contract along the radial direction of the cross section of the pile body in the expanding joint 2, and the diameter-variable mechanism has a contraction state of being completely contracted in the pile body and an expanding state of being extended out of the pile body.

Because the contraction state and the diameter expansion state of the variable diameter mechanism in the diameter expansion joint 2 need to be pushed by external force, the invention is also provided with the reamer 4 matched with the diameter expansion joint 2, and the reamer 4 can apply pushing force along the radial direction of the cross section of the pile body to the variable diameter mechanism, thereby converting the diameter expansion mechanism from the contraction state to the diameter expansion state.

In addition, in order to reduce the resistance in the pile body pile sinking process, according to the traditional method, the pile tip 8 is also arranged at the position of the section of the tubular pile 1 positioned at the bottommost end in the pile body. However, in order to form a bottom-expanding at the bottom of the pile body, the section of the tubular pile 1 at the bottom end in the pile body needs to be mounted on the pile tip 8 through a pile tip connecting hoop 5, and a bag-type bottom-expanding device 6 is mounted above the pile tip 8. The bag type bottom expanding device 6 is a special bottom expanding device with an inflatable bag inside and is provided with a grouting opening. The grouting port is used for being connected with an external grouting machine 10 through a grouting pipe 7, so that grout is pressed into an expandable bag of the bag-type bottom expanding device 6, the expandable bag pushes the pile tip 8 to be separated from the bag-type bottom expanding device 6 after grouting expansion, space is provided for further expansion of the expandable bag after the pile tip 8 is separated from the bag-type bottom expanding device 6, therefore, the peripheral soil body of the pile bottom is squeezed and expanded in the process that the expandable bag is continuously expanded, and a pile end expanding head can be formed after final grouting grout is solidified.

The specific structural forms of the tubular pile 1, the expanding joint 2, the tubular pile joint 3, the reamer 4, the pile tip connecting hoop 5, the bag-type bottom expanding device 6 and the pile tip 8 can be reasonably adjusted and optimized according to actual needs, and preferred methods of the tubular pile 1, the expanding joint 2, the tubular pile joint 3, the reamer 4, the pile tip connecting hoop 5, the bag-type bottom expanding device 6 and the pile tip 8 in the embodiments of the invention are described in detail below.

As a preferred form of the embodiment of the present invention, the tubular pile 1 may be prefabricated into a tubular section meeting strength according to certain parameters in a factory, and the processing manner is similar to that of a common prefabricated tubular pile, and is not described again. In addition, in order to be suitable for different construction scenes, the tubular piles 1 can be designed into different diameters and different length types, and pile bodies with different design parameters can be directly connected in a combined manner by the tubular piles 1 with different parameters.

As another preferred form of the embodiment of the present invention, as shown in fig. 2 and 3, the expanding joint 2 includes an upper end plate 201, a lower end plate 202, a connecting rib 203, an expanding blade 204, and a connecting bolt 205. The upper end plate 201 and the lower end plate 202 are arranged in parallel with a certain space kept therebetween for mounting the connection rib 203. In the present embodiment, the upper end plate 201 and the lower end plate 202 are both circular rings. As shown in fig. 4, the connecting ribs 203 have 4 pieces in total, and are arranged at equal angles in a circular ring direction. Each connecting rib plate 203 is connected with the upper end plate 201 at the top and connected with the lower end plate 202 at the bottom, so that a connecting structure capable of bearing loads in the direction vertical to the end plates is formed between the upper end plate 201 and the lower end plate 202 through 4 connecting rib plates 203. In the present embodiment, the diameter-variable mechanism that can expand and contract in the radial direction of the cross section of the pile body in the diameter-expanding joint 2 is realized by the diameter-expanding blades 204.

The expanding blades 204 are assembled with the connecting ribs 203 in a one-to-one correspondence. As shown in fig. 5, each expanding blade 204 includes a fan-shaped plate and an arc-shaped limiting plate, and the fan-shaped plate is provided with a slideway penetrating the plate, the width of the slideway is slightly greater than the thickness of the connecting rib plate 203, and the outer end of the slideway keeps a distance from the outer arc-shaped edge of the fan-shaped plate. The fan-shaped annular plate is arranged between the upper end plate 201 and the lower end plate 202, and the fan-shaped annular plate is sleeved outside the connecting rib plate 203 through a slide way, so that a sliding pair for limiting the fan-shaped annular plate to move along the radial direction is formed. Therefore, when the variable diameter mechanism is in the contracted state, the diameter expanding blades 204 are completely contracted between the upper end plate 201 and the lower end plate 202, and their tips do not protrude beyond the outer circumferential surfaces of the upper end plate 201 and the lower end plate 202, as shown in fig. 3. When the diameter-variable mechanism needs to be changed into a diameter-expanded state, the diameter-expanded blades 204 can be pushed radially by an external force to move outwards under the limiting action of the connecting rib plates 203, so that the outer edges of the blades extend out of the outer ring surfaces of the upper end plate 201 and the lower end plate 202. In the actual process, because the outer part of the pile body is generally the soil around the pile, in order to facilitate the diameter expansion blades 204 to be in the diameter expansion state, the outer annular surface of the diameter expansion blades 204 can be chamfered into a sharp angle. In addition, the purpose of providing the arc-shaped limiting plate at the inner arc-shaped edge of the fan annular plate is to control the limit position of outward movement of the diameter-expanding blades 204 in order to make the surface diameter-expanding blades 204 excessively spread away from the upper end plate 201 and the lower end plate 202. The arc-shaped limiting plates are arranged perpendicular to the fan-shaped annular plates, and a complete cylindrical surface is preferably formed when all the arc-shaped limiting plates are in a contracted state under the assembly state of the expanding joint 2. The size of the limiting plate should be larger than the gap between the upper end plate 201 and the lower end plate 202, and the arc limiting plate can be attached to the inner arc side of the upper end plate 201 and the lower end plate 202 when moving outwards to the limit position, so as to limit the arc limiting plate to move outwards continuously. As shown in fig. 6 and 7, the four expanding blades 204 in the variable diameter mechanism are in the expanded diameter state, at this time, the equivalent diameter is obviously expanded relative to the outer diameter of the pile body, and the four expanding blades 204 are horizontally inserted into the soil layer, so that a reliable expanded diameter structure is formed, and the bearing capacity and the uplift resistance of the pile body can be greatly increased.

In the present invention, the upper end plate 201 serves to connect the tube pile connectors 3 at the bottom of the upper tube pile 1, and the lower end plate 202 serves to connect the tube pile connectors 3 at the top of the lower tube pile 1. In order to facilitate the connection between the end plate and the tubular pile joint 3, the outward surfaces of the upper end plate 201 and the lower end plate 202 may be respectively provided with a connecting member for connecting the tubular pile joint 3. But the specific connecting piece form can be reasonably designed according to the specific form of the tubular pile joint 3

It should be understood that, although the number of the expanding blades 204 and the number of the connecting ribs 203 are 4 in the above embodiments, the number may be adjusted according to the actual implementation in other embodiments, and is at least 3, or may be more than 4.

As another preferred form of embodiment of the present invention, as shown in fig. 8, the tube pile joint 3 includes an end plate 301 and an end plate hole 302. The tubular pile joint 3 is fixed on the splicing end face of the tubular pile 1 through an end plate 301, and the fixation can be directly prefabricated during factory processing. In addition, the end plate 301 is provided with end plate holes 302 uniformly arranged along the circumference of the end plate to be connected and matched with the connecting pieces on the upper end plate 201 and the lower end plate 202. In order to ensure that the end plate holes 302 can be installed in a matching manner, the number and the positions of the end plate holes 302 are the same as the number of connecting pieces on the expanding joint 2, so that the connecting pieces on the upper end plate 201 and the lower end plate 202 can be exactly matched and fixed in the end plate holes 302.

As another preferred form of the embodiment of the present invention, the connecting member on the upper end plate 201 and the lower end plate 202 is a connecting bolt 205, and the threaded section of the connecting bolt 205 is fixed on the upper end plate 201 or the lower end plate 202, but the bolt head needs to keep a distance from the surface of the end plate. The connecting bolt 205 may be welded or screwed to the upper end plate 201 and the lower end plate 202. The end plate hole 302 on the end plate 301 is a variable diameter hole, the variable diameter hole is provided with a first hole area and a second hole area which are communicated with each other, wherein the size of the hole of the first hole area can be used for the bolt head of the connecting bolt 205 to extend into the first hole area, and when the connecting bolt 205 and the upper end plate 201 or the lower end plate 202 move relatively, the bolt head can move from the first hole area to the second hole area. However, in order to ensure the connection fixing function, the size of the hole of the second hole area needs to ensure that the bolt head cannot be directly separated from the second hole area. It should be noted that, since the size of the bolt head is larger than the size of the hole of the second hole area, but the bolt head needs to be able to move from the first hole area to the second hole area, the second hole area is actually a hole with an inner cavity, and the size of the hole is smaller than the size of the bolt head, but the inner cavity below the hole can still accommodate the bolt head.

Referring to fig. 8, the reducing hole in this embodiment is an 8-shaped hole having a large hole end and a small hole end, which correspond to the first hole area and the second hole area, respectively. The bolt head of the connecting bolt 205 extends from the large hole end and then moves to the small hole end for clamping and fixing. In order to realize the inner cavity at the small hole end, the end plate 301 may be fixed on the splicing end face of the tubular pile 1 at intervals, and the interval height may accommodate the bolt head of the connecting bolt 205. In order to ensure sufficient tensile strength at the eyelet end, the hole peripheral edge of the eyelet end may be provided with a reinforcing structure. In addition, in order to achieve the function of locking by rotation, the arrangement of the end plate holes 302 on the end plate 301 needs to be consistent, that is, the first hole areas of all the end plate holes 302 need to be always located in the same direction as the second hole areas when viewed in the clockwise direction.

As another preferred form of embodiment of the present invention, as shown in fig. 9, the reamer 4 includes a drive mechanism and sets of cross arms 405 and a reamer end plate 410. Wherein, in each set of cross arms 405 and counterbore end plate 410, counterbore end plate 410 is connected to the drive mechanism by one of the cross arms 405. Under the driving of the driving mechanism, all the reaming end plates 410 are synchronously stretched and contracted to form a gathering state and an expanding state. In the gathered state, the gathered sizes of all the reaming end plates 410 can integrally extend into the enclosed space of the arc limiting plates of all the expanding blades 204 in the contraction state; in the expanded state, the expanded size of all the expanding end plates 410 enables all the expanded diameter blades 204 to prop up the expanded arc limiting plates in the inner rings of the upper end plate 201 and the lower end plate 202, so that all the expanded diameter blades 204 reach the expanded diameter state.

It should be noted that the specific form of the driving mechanism and the cooperation relationship with the cross arm 405 may be adjusted according to actual conditions, and in this embodiment, the driving mechanism employs a hydraulic linear driving device. The hydraulic linear drive comprises a hydraulic ram 401, a hydraulic piston rod 402, a first hydraulic line 403 and a second hydraulic line 404. The piston head of the hydraulic piston rod 402 is assembled in the hydraulic oil cylinder 401 and can freely slide, the piston head divides the hydraulic oil cylinder 401 into an upper area and a lower area, the upper hydraulic cylinder is connected with a first hydraulic pipe 403, and the lower hydraulic cylinder is connected with a second hydraulic pipe 404; and the output rod connected with the piston head extends out of the hydraulic oil cylinder 401, and can be pushed to output power outwards through different hydraulic oil input and output states of the first hydraulic pipe 403 and the second hydraulic pipe 404. The cross arm 405 is a scissor-like structure consisting of two links with a pin 407 in between. In this embodiment there are 4

cross arms

405 and 4 reaming end plates 410 in common, with the inner sides of the 4 cross arms 405 fitting together on the same set of fixed end block 408 and sliding end block 409 and the outer sides fitting on the 4 reaming end plates 410 respectively. The hydraulic oil cylinder 401 is located at the center of the whole underreamer 4, the bottom of the hydraulic oil cylinder 401 is fixedly connected with a sliding end block 409, the output rod of the piston rod 402 passes through a guide hole in the sliding end block 409 and then is fixedly connected with a fixed end block 408, and the output rod of the piston rod 402 can freely slide in the guide hole. Thus, the relative distance between fixed end block 408 and sliding end block 409 can be varied by piston rod 402, and hydraulic power is converted into radial thrust outside cross arm 405. As shown in fig. 10, as the relative distance between fixed end block 408 and sliding end block 409 decreases, cross arm 405 pushes reamer end plate 410 outward to an expanded state. As shown in fig. 11 and 12, the collapsed state and the expanded state of all the reamer end plates 410 correspond to the collapsed state and the expanded state of all the expanded diameter blades 204, respectively.

In order to avoid excessive radial displacement of the output, the reamer end plate 410 is provided with a stopper 406, one end of the cross arm 405 needs to slide in a slide groove of the stopper 406, and both ends of the slide groove constitute two limit positions at which the cross arm 405 rotates. The specific size parameters of the limiter 406 need to be reasonably and optimally designed according to the matching condition with 4 expanding blades 204 in the expanding joint 2, so as to meet the function requirement.

As another preferred form of the embodiment of the present invention, as shown in fig. 13, the pile tip connecting hoop 5 is composed of a first ring-shaped section 502, a second ring-shaped section 504, a top surface 501 for closing the top of the first ring-shaped section, and a step surface 503 for connecting the two ring-shaped sections, and has a convex shape with an open bottom as a whole. Wherein the external diameter of first ring section 502 is unanimous with the internal diameter of tubular pile 1, can just imbed in tubular pile 1. The outer diameter of the second annular section 504 is the same as that of the tubular pile 1, and does not protrude out of the side wall of the pile body.

As another preferred form of the embodiment of the present invention, as shown in fig. 14, the pile tip 8 may include a cross pile tip plate 801 and a back cover 802, the cross pile tip plate 801 is welded to the back cover 802, and a pile tip chamfer 803 is provided on the cross pile tip plate 801 for facilitating insertion into soil.

As shown in fig. 15, in the assembled state of the tubular pile 1, the tubular pile connector 3, the pile tip connection hoop 5 and the pile tip 8, the tubular pile connector 3 at the end of the tubular pile 1 is supported on the step surface 503 of the pile tip connection hoop 5, the first annular section 502 extends into the inner cavity of the tubular pile 1, and the inner diameter of the second annular section 504 is the same as the diameter of the back cover 802 of the pile tip 8. The second annular section 504 is actually a ring of flanged edge arranged at the lower part of the step surface 503, the height of the second annular section does not need to be very high, and the second annular section can hoop the pile tip 8 and can not topple over in the pile sinking process. The second ring section 504 is fastened to the back cover 802 of the post 8, but the fastening between the two is detachable, i.e. the two will be detached when receiving the force of the deviation. The top surface 501, the first ring segment 502 and the top surface of the pile tip 8 thereby enclose a receiving space. In the bladder-type bottom expanding device 6 composed of the inflatable bladder 601 and the bladder connector 602, the inflatable bladder 601 is placed in the accommodating space, and the bladder connector 602 extends out of the stake point connecting hoop 5 through the through hole formed in the top surface 501. The bladder joint 602 may be used to connect the grouting machine 10 through the grouting pipe 7. Grouting liquid 603 is injected into the expandable bladder 601 through the grouting pipe 7 by using a grouting machine 10, the bladder 601 is expanded under the action of grouting pressure, the pile tip 8 is pushed to be separated from the second annular section 504, space is created for expansion of the expandable bladder 601, and soil around the expandable bladder 601 is further squeezed and expanded through grouting to form a pile tip expanded head.

As another preferred form of the embodiment of the present invention, since the bag connector 602 is located at the pile bottom, it is difficult to butt-joint with the grouting pipe 7, so that the end of the outlet end of the grouting pipe 7 adopts a magnetic connector, and is self-locked under the action of the grouting pressure after being connected with the bag connector 602, and can be freely pulled out when the grouting pressure disappears after the grouting is completed. At the same time, a centering device 9 is designed to assist in keeping the bottom end of the grouting pipe 7 centered on the shaft axis. As shown in fig. 16, the centering device 9 includes a sleeve 901 and telescopic rods 902, the sleeve 901 is used for being sleeved on a pipeline extending into the tubular pile 1, and the four telescopic rods 902 are annularly and equally fixed on the sleeve 901 at equal angles, and form an included angle of 90 degrees with each other. Of course, the telescopic rods 902 on the casing 901 can also be adjusted according to the actual situation, and at least three telescopic rods 902 are provided. The telescopic link 902 can be synchronous flexible according to the internal diameter size of tubular pile 1, and the ware 9 that centers in is fixed in slip casting pipe 7, makes sleeve 901 and inside slip casting pipe 7 transfer the in-process in tubular pile 1 and is placed the in-process all the time and center. To ensure that the sleeve 901 is always centered, the length of all telescopic rods 902 should be adjusted to be equal to the difference between the inner radius of the tube pile 1 and the outer radius of the sleeve 901.

In addition to the above described centring of the grout tube 7, the centraliser 9 may also be applied to the under-reamer 4 on two hydraulic lines, which may take the form of rigid pipes located on the central axis of the under-reamer 4, as shown in figures 11 and 12. Therefore, after the centering device 9 is used for sleeving the first hydraulic pipe 403 and the second hydraulic pipe 404 to be lowered, the reamer 4 can be centered in the tubular pile 1 all the time.

It should be noted that the specific material of each component in the present invention is not limited, so as to meet the requirements of the corresponding usage scenario for material strength and life, for example, steel material may be adopted.

Based on the above-mentioned integrated apparatus for pipe pile extension, bottom expansion and diameter expansion as shown in fig. 1 to 12, in another embodiment of the present invention, there is further provided a pipe pile extension, bottom expansion and diameter expansion construction method using the integrated apparatus, which sequentially comprises the following steps:

s1, determining a pile position coordinate according to a design drawing, and placing a pile tip 8 on the ground of a coordinate point; the bladder type bottom expanding device 6 is installed in the pile tip connecting hoop 5, the pile tip connecting hoop 5 is held by the bladder connector 602 to extend out of the pile tip connecting hoop 5 through the through hole formed on the top surface 501, and then the pile tip connecting hoop 5 with the bladder type bottom expanding device 6 installed is fastened and fixed on the pile tip 8. And the splicing end faces of all the tubular piles 1 to be connected are respectively fixed with a tubular pile joint 3.

S2, vertically assembling the first section of tubular pile 1 on the pile tip connecting hoop 5, and inserting a first annular section 502 at the upper part of the pile tip connecting hoop 5 into the tubular pile 1; and then, driving the first section of tubular pile 1 into the soil layer by using pile driving equipment, and only keeping the pile top part exposed out of the ground.

It should be noted that the pile sinking process of the tubular pile 1 belongs to the prior art, and can be implemented by the prior art such as static pressure method or hammering method, and the like, which will not be described in detail. In the pile sinking process, in order to facilitate the connection of the subsequent expanding joint 2, the top of the tubular pile 1 is preferably controlled to be exposed out of the ground by about 1 meter.

S3, placing an expanding joint 2 on the tubular pile joints 3 on the pile tops of the tubular piles 1 exposed out of the ground, adjusting the positions to enable the bolt heads of the connecting bolts 205 on the lower end plate 202 to correspondingly extend into the first hole areas of the end plate holes 302 of the tubular pile joints 3 one by one, and then rotating the expanding joint 2 to enable all the bolt heads of the connecting bolts 205 to move from the first hole areas to the second hole areas, so that the connecting of the expanding joint 2 and the tubular piles 1 below is completed; and then placing the tubular pile joint 3 at the bottom of the other section of tubular pile 1 on the upper end plate 201 of the expanding joint 2, adjusting the position to enable the bolt heads of the connecting bolts 205 on the upper end plate 201 to correspondingly extend into the first hole areas of the end plate holes 302 of the tubular pile joint 3 one by one, and then rotating the tubular pile 1 above to enable all the bolt heads of the connecting bolts 205 to move from the first hole areas to the second hole areas, thereby completing the connection of the expanding joint 2 and the tubular pile 1 above. Therefore, the upper and lower two sections of tubular piles 1 are clamped on the upper and lower surfaces of the expanding joint 2 through the tubular pile joints 3, the upper and lower two sections of tubular piles 1 are connected and fixed, and then the pile is pressed downwards continuously, so that the upper tubular pile 1 is driven into the soil layer, and only the pile top part is left to be exposed out of the ground.

And S4, continuously repeating the step S3 until all the tubular piles 1 are driven into the soil layer.

And S5, after all the tubular piles 1 are driven into the soil layer, taking the underreamer 4, initializing and adjusting all the underreamer end plates 410 to be in a gathered state, and then lowering the underreamer 4 to the position of the first expanded joint 2 to form a structure shown as a in the figure 17. And starting the driving mechanism to enable all the reaming end plates 410 to synchronously extend outwards to an expansion state, wherein each reaming end plate 410 can respectively push the corresponding expanding blades 204 to move outwards in the expansion process, so that all the expanding blades 204 in the first expanding joint 2 synchronously extend out of the pile body, and further an expanding structure for improving the bearing capacity of the pile foundation is formed. Then all the reaming end plates 410 are contracted again to the gathered state, and then are lowered to the position of the next expanding joint 2, and the driving mechanism is started again to enable all the reaming end plates 410 to synchronously extend outwards to the expanded state, so that the next expanding joint 2 is also changed to the expanded state. This process is repeated until all the expanded joints 2 are in the expanded state, as shown in fig. 17 b. The reamer 4 is removed by keeping all reamer end plates 410 together.

It should be noted that if the reamer 4 adopts the aforementioned rigid hydraulic pipe, the sleeve 901 of the centering device 9 can be sleeved on the grouting pipe 7 connected with the grouting machine 10 in advance, and the length of the telescopic rods 902 can be adjusted according to the inner diameter of the tubular pile 1, so that the length of all the telescopic rods 902 is equal to the difference between the inner radius of the tubular pile 1 and the outer radius of the sleeve 901. Therefore, when the gathered reamer 4 sinks into the next expanding joint 2, the reamer can just enter the enclosed area of the gathered 4 arc limiting plates. Of course, since the 4 arc-shaped limiting plates after the previous expanding joint 2 is expanded can reduce the partial position diameter of the cross section of the inner cavity of the pile body, the 4 telescopic rods 902 of the centering device 9 need to stagger the positions of the 4 arc-shaped limiting plates in the process of sinking the reamer 4 into the next expanding joint 2.

S5, sleeving the sleeve 901 of the centering device 9 on the grouting pipe 7 connected with the grouting machine 10, and adjusting the length of the telescopic rods 902 according to the inner diameter of the tubular pile 1 to enable the length of all the telescopic rods 902 to be equal to the difference between the inner radius of the tubular pile 1 and the outer radius of the sleeve 901; then the grouting pipe 7 with the centering device 9 is gradually lowered along the inner cavity of the pile body, and the telescopic rod 902 of the centering device 9 keeps horizontal in the lowering process, so that the grouting pipe 7 can be always kept on the central axis of the pile body. When the grouting pipe 7 is lowered to the pile bottom, the grouting pipe is connected and locked with the bag connector 602 through magnetic attraction, at the moment, the grouting machine 10 is started to pressurize and inject grouting slurry into the expandable bag 601, the expandable bag 601 is expanded under the action of grouting pressure to push the pile tip 8 to be separated from the pile tip connection hoop 5, the pile tip continues to extend out of the pile bottom, the surrounding soil body is squeezed and expanded, and grouting is stopped when the grouting amount or the grouting pressure meets the design requirement, so that the structure is shown as c in fig. 17. After grouting, the centering device 9 and the grouting pipe 7 are pulled out, and after the cement slurry is cured, a pile end expanded head for improving the bearing capacity of the pile bottom is formed, as shown in d in fig. 17.

It should be noted that, the above S1 to S5 describe a pile sinking construction process of one pile body, but a plurality of pile foundation sites that need to be constructed may exist in one construction site, and therefore the above processes may be repeated for each site, and no repeated description is given here. The invention can improve the side resistance and end resistance of pile, improve the bearing capacity of pile foundation, especially the resistance to pulling, mainly the side friction resistance, so it can reduce the length and number of pile, and reduce the cost.

In another preferred form of the embodiment of the present invention, the maximum expanded diameter of the expandable bladder 601 is 1.5 to 2 times the outer diameter of the tubular pile 1.

As another preferable form of the embodiment of the present invention, the grouting pressure of the grouting machine 10 is 0.5 to 2MPa.

As another preferred form of the embodiment of the present invention, the grouting liquid 603 is made of cement paste or fine aggregate concrete, and the grouting amount and the grouting pressure are controlled in a dual manner, so that the grouting can be stopped when any one of the grouting amount and the grouting pressure meets the design requirement.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pipe pile splicing, bottom expanding and diameter expanding integrated device is characterized by comprising a pipe pile (1), a diameter expanding connector (2), a pipe pile connector (3), an underreamer (4), a pile tip connecting hoop (5), a bag-type bottom expanding device (6) and a pile tip (8);

the multiple sections of tubular piles (1) are sequentially spliced along the vertical direction to form a pile body; the splicing end faces of any two sections of adjacent tubular piles (1) are respectively fixed with a tubular pile joint (3), and the two tubular pile joints (3) are clamped and fixed through the expanding joint (2), so that the two sections of adjacent tubular piles (1) are reliably connected; the diameter-expanding joint (2) is internally provided with a diameter-variable mechanism which can radially extend and retract along the cross section of the pile body, and the diameter-variable mechanism has a contraction state of completely contracting in the pile body and an diameter-expanding state of extending out of the pile body;

the reamer (4) is used for applying a pushing force along the radial direction of the cross section of the pile body to the diameter-variable mechanism, so that the diameter-variable mechanism is converted into a diameter-expanded state from a contraction state;

a section of tubular pile (1) positioned at the bottommost end in the pile body is arranged on a pile tip (8) through a pile tip connecting hoop (5); the bag type bottom expanding device (6) is arranged above the pile tip (8) and is provided with a grouting port;

the grouting port is used for being connected with an external grouting machine (10) through a grouting pipe (7) so as to press grout into an expandable bag of the bag type bottom expanding device (6), and after grouting and expansion of the expandable bag, a pile tip (8) is pushed to be separated from the bag type bottom expanding device (6) and a peripheral soil body of the pile bottom is further squeezed and expanded by the bag to form a pile end expanded head.

2. The tubular pile extension, bottom expanding and diameter expanding integrated device according to claim 1, wherein the diameter expanding joint (2) comprises an upper end plate (201), a lower end plate (202), a connecting rib plate (203), diameter expanding blades (204) and connecting bolts (205); the upper end plate (201) and the lower end plate (202) are arranged in parallel at intervals, and a connecting structure capable of bearing loads in the direction vertical to the end plates is formed between the upper end plate and the lower end plate by clamping and fixing a plurality of connecting rib plates (203); the diameter-expanding blades (204) and the connecting rib plates (203) are assembled in a one-to-one correspondence mode, each diameter-expanding blade (204) comprises a fan-shaped annular plate and an arc limiting plate, a slide way penetrating through the plate bodies is formed in the fan-shaped annular plate, the fan-shaped annular plate is installed between the upper end plate (201) and the lower end plate (202), the fan-shaped annular plate is sleeved outside the connecting rib plates (203) through the slide way to form a sliding pair for limiting the radial movement of the fan-shaped annular plate, the size of the arc limiting plate is larger than the gap between the upper end plate (201) and the lower end plate (202), and the arc limiting plates can be limited to move outwards continuously when moving outwards to the limiting position; and the outward plate surfaces of the upper end plate (201) and the lower end plate (202) are respectively provided with a connecting piece for connecting the tubular pile joint (3).

3. The tubular pile splicing, bottom expanding and diameter expanding integrated device according to claim 2, wherein the tubular pile joint (3) comprises an end plate (301) and an end plate hole (302), the end plate (301) is fixed on the splicing end face of the tubular pile (1); the end plate holes (302) are uniformly arranged along the circumference of the end plate, the number and the positions of the end plate holes are the same as those of the connecting pieces on the expanding joint (2), and the connecting pieces can be matched and fixed in the end plate holes (302).

4. The pipe pile splicing, bottom expanding and diameter expanding integrated device according to claim 3, wherein the connecting pieces on the upper end plate (201) and the lower end plate (202) are connecting bolts (205), the threaded sections of the connecting bolts (205) are fixed on the end plates, and the bolt heads of the connecting bolts are spaced from the surface of the end plates; the variable-diameter hole is adopted in end plate hole (302) on end plate (301), have the first hole district and the second hole district of intercommunication in the variable-diameter hole, wherein the hole size in first hole district can supply the bolt head stretches into, and the bolt head can move to the second hole district from first hole district, but the hole size in second hole district can't make the bolt head directly break away from the second hole district.

5. The integrated pipe pile extension, bottom reaming and diameter expanding device according to claim 2, wherein the reamer (4) comprises a driving mechanism and a plurality of groups of cross arms (405) and reaming end plates (410); wherein in each set of cross arms (405) and reamer end plates (410), the reamer end plates (410) are connected to the drive mechanism by the cross arms (405); under the driving of the driving mechanism, all the reaming end plates (410) synchronously stretch and retract to form a gathering state and an expanding state; in the gathering state, the gathered sizes of all the reaming end plates (410) can integrally extend into the enclosed space of the arc-shaped limiting plates of all the expanding blades (204) in the contraction state; in an expanded state, the expanded size of all the expanding end plates (410) can enable all expanding blades (204) to prop up the expanded arc limiting plates in the inner rings of the upper end plate (201) and the lower end plate (202).

6. The tubular pile extension, bottom expansion and diameter expansion integrated device according to claim 4, wherein the pile tip connecting hoop (5) is composed of a first annular section (502), a second annular section (504), a top surface (501) for closing the top of the first annular section and a step surface (503) for connecting the two annular sections, and the whole device is in a convex shape with an open bottom; the outer diameter of the first annular section (502) is consistent with the inner diameter of the tubular pile (1), and the outer diameter of the second annular section (504) is consistent with the outer diameter of the tubular pile (1); in an assembly state, a tubular pile joint (3) at the end part of a tubular pile (1) is supported on the step surface (503), the first annular section (502) extends into the inner cavity of the tubular pile (1), the second annular section (504) can be detachably buckled on the pile tip (8), and the top surface (501), the first annular section (502) and the top surface of the pile tip (8) are combined to form an accommodating space; the bladder type bottom expanding device (6) comprises an expandable bladder (601) and a bladder joint (602); the inflatable bladder (601) is placed in the accommodation space; the bladder connector (602) extends through a through hole in the top surface (501) beyond the spike connector ferrule (5) for injecting a grouting fluid (603) into the inflatable bladder (601).

7. The tubular pile extension, bottom expanding and diameter expanding integrated device according to claim 1, wherein the end of the outlet end of the grouting pipe (7) is a magnetic joint capable of being connected with the bag joint (602) in a self-locking manner.

8. A tubular pile extension, bottom expanding and diameter expanding integrated device according to claim 1, characterized by further comprising a centering device (9) for keeping a pipeline extending into the tubular pile (1) centered all the time; the centering device (9) comprises a sleeve (901) and at least three telescopic rods (902), wherein the sleeve (901) is used for fixing a ring sleeve on a pipeline extending into the tubular pile (1), all the telescopic rods (902) are perpendicularly fixed on the sleeve (901) in an annular equiangular mode, the telescopic rods (902) can stretch out and draw back synchronously according to the inner diameter of the tubular pile (1), and the sleeve (901) and the pipeline penetrating into the interior are centered all the time in the up-and-down moving process of the tubular pile (1).

9. A pipe pile extension base expanding and diameter expanding construction method using the integrated device of claim 6 is characterized by comprising the following steps:

s1, determining a pile position coordinate according to a design drawing, and placing a pile tip (8) on the ground of a coordinate point; installing the bag-type bottom expanding device (6) in the pile tip connecting hoop (5), keeping the bag joint (602) to extend out of the pile tip connecting hoop (5) through a through hole formed in the top surface (501), and then buckling and fixing the pile tip connecting hoop (5) provided with the bag-type bottom expanding device (6) on the pile tip (8); respectively fixing a pipe pile joint (3) on the splicing end faces of all the pipe piles (1) to be connected;

s2, vertically assembling the first section of tubular pile (1) on the pile tip connecting hoop (5), and inserting a first annular section (502) at the upper part of the pile tip connecting hoop (5) into the tubular pile (1); then, driving the first section of tubular pile (1) into a soil layer by using pile driving equipment, and only keeping the pile top part exposed out of the ground;

s3, placing an expanding joint (2) on the tubular pile joint (3) of the pile top of the tubular pile (1) exposed out of the ground, adjusting the position to enable the bolt heads of the connecting bolts (205) on the lower end plate (202) to correspondingly extend into a first hole area of an end plate hole (302) of the tubular pile joint (3), and then rotating the expanding joint (2) to enable the bolt heads of all the connecting bolts (205) to move from the first hole area to a second hole area to complete connection of the expanding joint (2) and the tubular pile (1) below; placing the other section of tubular pile (1) on an upper end plate (201) of the expanded joint (2), adjusting the position to enable the bolt heads of the connecting bolts (205) on the upper end plate (201) to correspondingly extend into a first hole area of an end plate hole (302) of the tubular pile joint (3) one by one, and then rotating the upper tubular pile (1) to enable the bolt heads of all the connecting bolts (205) to move from the first hole area to a second hole area to complete the connection of the expanded joint (2) and the upper tubular pile (1); after the upper and lower sections of tubular piles (1) are connected and fixed, continuously pressing the piles downwards to drive the upper tubular piles (1) into the soil layer and only keep the pile tops exposed out of the ground;

s4, continuously repeating the step S3 until all the tubular piles (1) are driven into the soil layer;

s5, after all the tubular piles (1) are driven into a soil layer, lowering the reamers (4) with all the reaming end plates (410) in a gathered state to the positions of the first expanding joints (2), starting a driving mechanism to enable all the reaming end plates (410) to synchronously extend outwards to an expanded state, wherein each reaming end plate (410) can respectively push the corresponding expanding blades (204) to move outwards in the expanding process, so that all the expanding blades (204) in the first expanding joints (2) synchronously extend out of a pile body to form an expanding structure for improving the bearing capacity of a pile foundation; then all the reaming end plates (410) are contracted again to a gathering state, and then are put down to the position of the next expanding joint (2) and are changed into an expanding state; continuously repeating the steps until all the expanding joints (2) are changed into the expanding state, and taking out the reamer (4);

s5, sleeving a sleeve (901) of a centering device (9) on a grouting pipe (7) connected with a grouting machine (10), and adjusting the length of telescopic rods (902) according to the inner diameter of the tubular pile (1) to enable the length of all the telescopic rods (902) to be equal to the difference between the inner radius of the tubular pile (1) and the outer radius of the sleeve (901); then a grouting pipe (7) with a centering device (9) is placed to the bottom of the pile to be connected with a bag joint (602), a grouting machine (10) is started to pressurize and inject grouting slurry into an expandable bag (601), the expandable bag (601) is expanded under the action of grouting pressure to push a pile tip (8) to be separated from a pile tip connection hoop (5), the pile tip continues to extend out of the pile bottom and then squeeze and expand peripheral soil, the centering device (9) and the grouting pipe (7) are pulled out after grouting is completed, and a pile end expansion head for improving the bearing capacity of the pile bottom is formed after cement slurry is solidified.

10. The tubular pile extension base expanding and diameter expanding construction method according to claim 9, characterized in that, preferably, the maximum expanded diameter of the expandable bladder (601) is 1.5-2 times of the outer diameter of the tubular pile (1); preferably, the grouting pressure of the grouting machine (10) is 0.5-2 MPa; preferably, the grouting liquid (603) is made of cement paste or fine aggregate concrete, the grouting amount and the grouting pressure are controlled in a double mode, and grouting can be stopped when any one of the grouting liquid and the grouting pressure meets the design requirement.