CN108894218B

CN108894218B - Prestressed concrete precast pile

Info

Publication number: CN108894218B
Application number: CN201810850212.7A
Authority: CN
Inventors: 周曙东; 周芳; 陈家冬; 尚学伟; 周浩达
Original assignee: Jiangsu Foundation Engineering Co ltd
Current assignee: Jiangsu Foundation Engineering Co ltd
Priority date: 2018-07-28
Filing date: 2018-07-28
Publication date: 2020-09-04
Anticipated expiration: 2038-07-28
Also published as: CN108894218A

Abstract

The invention discloses a prestressed concrete precast pile, which belongs to the field of pile foundation engineering and solves the technical problem that the contact area between the outer surface of the precast pile and a foundation is not high, so that the seismic performance of the precast pile is poor. The area of contact of pile body and butt can be increased to the location nail, can restrict the displacement of pile body in vertical direction simultaneously, and the effectual fixed effect that has improved pile body and ground has improved the anti-seismic performance of precast pile.

Description

Prestressed concrete precast pile

Technical Field

The invention relates to the field of pile foundation engineering, in particular to a prestressed concrete precast pile.

Background

In the pretensioned prestressed concrete pile of the existing building standard, a prestressed tendon is mainly used for meeting the load generated by the hoisting requirement of a precast pile, but can not provide bearing capacity, so that the prestressed tendon has limited effect; in addition, the prestressed concrete pile is a prestressed member, has low ductility, is easy to generate brittle failure, and cannot resist larger tensile force and bending stress, so the horizontal bearing capacity of the existing pretensioned prestressed concrete pile is relatively weak.

Thus, the invention patent with the publication number of CN 101851916B provides a precast concrete pile, in which at least a part of the main reinforcements are non-prestressed reinforcements. The bending resistance bearing capacity and the shearing resistance bearing capacity of the reinforced partially prestressed concrete precast pile are greatly improved compared with the original prestressed concrete precast pile.

In order to facilitate the driving of the precast pile, the precast pile in the prior art is pressed into the foundation, and the outer shape of the precast pile is regular, such as square or cylindrical, so that the contact area between the outer surface of the precast pile and the foundation is not high after the pile is pressed, and the seismic performance of the precast pile is poor.

Disclosure of Invention

The invention aims to provide a prestressed concrete precast pile, which not only can facilitate pile driving, but also can improve the contact area of the precast pile and a foundation and improve the seismic resistance of the precast pile.

The technical purpose of the invention is realized by the following technical scheme: the utility model provides a prestressed concrete precast pile, includes the pile body, the pile body comprises concrete and steel reinforcement cage, the steel reinforcement cage includes the main muscle that a plurality of circumference arrays set up, and is a plurality of the main muscle passes through the stirrup and links to each other, be fixed with the location section of thick bamboo of burying underground in the concrete on the main muscle, the opening and the pile body external world of a location section of thick bamboo communicate with each other, be equipped with the location nail in the location section of thick bamboo, the location nail slides along a location section of thick bamboo length direction and sets up in a location section of thick bamboo, be equipped with the first elastic component that the drive location nail stretches out a location section of thick bamboo in the location section of thick bamboo, still be equipped with the mounting of fixing the location.

By adopting the technical scheme, the fixing piece fixes the positioning nail in the positioning cylinder before piling, so that the outer surface of the pile body is still cylindrical, the resistance force of the pile body during pressing cannot be increased, after piling is finished, the fixing of the fixing piece and the positioning cylinder is released, the positioning nail slides outwards under the action of the first elastic piece, the positioning nail can increase the contact area between the pile body and the butt joint and can limit the displacement of the pile body in the vertical direction when the pile body is driven into the foundation on the periphery of the pile body, the fixing effect of the pile body and the foundation is effectively improved, and the anti-seismic performance of the precast pile is improved.

Preferably, the positioning nail is provided with a spine portion towards one end of the opening of the positioning barrel, the fixing piece comprises a fixing rod arranged along the length direction of the positioning nail, one end of the fixing rod is fixed on the end face, away from the spine portion, of the positioning nail, the other end of the fixing rod extends out of the bottom of the positioning barrel, a wedge block capable of being abutted against the positioning barrel is arranged at the extending end of the fixing rod, and a through hole for the fixing rod and the wedge block to extend out is formed in the bottom of the positioning barrel.

By adopting the technical scheme, the spine part is arranged, so that the positioning nail can be conveniently driven into the foundation around the pile body, and after the fixing rod extends out of the positioning cylinder from the through hole, the plane of the wedge block can be abutted against the positioning cylinder under the elastic action of the first elastic piece, so that the positioning nail is fixed in the positioning cylinder.

Preferably, the number of the fixing rods is two, the fixing rods are arranged in parallel, and wedge blocks on the two fixing rods are symmetrically arranged.

By adopting the technical scheme, the two fixing rods can limit the position of the positioning nail at the same time, so that the stress of the positioning nail is very uniform during fixing, and the fixing effect of the positioning nail is good.

Preferably, the main muscle overcoat is equipped with the installation cover, the installation cover is a plurality of and sets up along main muscle length direction array, the main muscle surface is equipped with the cross slot, the eccentric through hole that communicates with the cross slot that is equipped with on the installation cover, work as when the cross slot communicates with each other with the through hole, wear to be equipped with in the through hole and be used for the steel wire of stirrup ligature on the installation cover.

By adopting the technical scheme, when the hoop reinforcement fixing device is installed, the steel wire penetrates through the through hole and the transverse groove, the fixing sleeve is positioned on the main reinforcement, the fixing position of the hoop reinforcement on the main reinforcement can be determined, and then the hoop reinforcement is directly bound on the fixing sleeve, so that the fixing of the hoop reinforcement and the fixing sleeve can be realized, and the fixing speed of the hoop reinforcement is improved.

Preferably, the number of the transverse grooves is a plurality, and the transverse grooves are arranged in an array along the length direction of the main ribs.

By adopting the technical scheme, the mounting sleeve can be fixed at any position on the main reinforcement to adapt to the fixation of stirrups with different screw pitches, and the adaptability is improved.

As preferred, the owner muscle both ends are equipped with when pouring the end plate fixed with the mould, the owner muscle both ends are equipped with to the opposite external screw thread soon, two rotate on the end plate be connected with main muscle tip thread fit's nut, the cover is equipped with outer ring gear on the nut outer peripheral face, the end plate center is rotated and is equipped with the driving gear with each outer ring gear meshing.

By adopting the technical scheme, when the main ribs are required to be tensioned, only the driving gear on one of the end plates needs to be rotated to drive the nuts on the corresponding end plate to rotate, and the external threads at the two ends of the main ribs are opposite in rotation direction, so that the two ends of the main ribs can be driven to be away from each other, the tensioning of all the main ribs is realized, the working efficiency is improved, and the equal prestress on each main rib is ensured.

Preferably, the outer ring gear is slidably provided on the nut in the axial direction of the nut, and the outer ring gear has a first state of meshing with the drive gear and a second state of sliding out of alignment with the drive gear.

By adopting the technical scheme, when the main rib is not required to be tensioned, the outer gear ring on the main rib is slid to the second state, the outer gear ring is not in contact with the driving gear, the driving gear does not drive the nut to rotate, and the main rib can be selectively tensioned and prestressed.

Preferably, the outer peripheral surface of the end plate is provided with an open slot corresponding to the nut, the nut is rotatably arranged in the open slot, a limit gear for limiting the nut to slide outwards is rotatably arranged between two adjacent nuts on the end plate, and the limit gear is meshed with the outer gear ring on the adjacent nut.

By adopting the technical scheme, the outer gear ring is fixed at the corresponding position on the end plate under the limiting action of the limiting gear and the driving gear. The driving gears with different diameters are replaced, and the limiting gears slide, so that pouring of pile bodies with different diameters can be achieved.

Preferably, the stirrups are spirally arranged, the number of the stirrups is two, and the rotation directions of the two stirrups are opposite.

By adopting the technical scheme, the coverage area of the stirrups can be further improved, so that the bearing capacity of the pile body in the horizontal direction is better.

Preferably, the thread pitch of the stirrup at the middle of the main rib is smaller than the thread pitch of the stirrup at the two ends of the main rib.

By adopting the technical scheme, the stirrups in the middle of the main reinforcement are arranged densely, so that the structural strength in the middle of the reinforcement cage can be effectively improved, the bending resistance in the middle of the pile body is further improved, the structural strength of the pile body is improved, and the transportation is convenient.

In conclusion, the invention has the following beneficial effects:

1. the fixing effect of the pile body and the foundation is good;

2. the manufacturing is convenient, and the pouring efficiency is high.

Drawings

Fig. 1 is a schematic diagram of the pile structure of the embodiment (with the end plate and the nut removed);

fig. 2 is a schematic diagram of pile casting of the present embodiment (without removing end plates and nuts);

fig. 3 is a schematic structural view of the reinforcement cage of the present embodiment;

FIG. 4 is a binding diagram of the stirrup of the present embodiment;

FIG. 5 is a schematic structural view of a positioning cylinder and a mounting cylinder of the present embodiment;

FIG. 6 is an assembled sectional view of the positioning cylinder of the present embodiment;

fig. 7 is a schematic view of the nut driving of the present embodiment.

In the figure, 1, a pile body; 2. a reinforcement cage; 21. a main rib; 22. hooping; 3. installing a sleeve; 31. a through hole; 4. a transverse groove; 41. a steel wire; 5. a positioning cylinder; 51. positioning nails; 511. a spike portion; 52. fixing the rod; 521. a wedge block; 53. a first spring; 54. a second spring; 55. a through hole; 6. an end plate; 61. an open slot; 611. a chute; 62. a driving gear; 63. a T-shaped slot; 64. a slider; 641. a limit gear; 7. a nut; 71. an outer ring gear; 711. a sleeve; 72. a convex ring.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The utility model provides a prestressed concrete precast pile, refer to fig. 1, including pile body 1, pile body 1's appearance is hollow cylinder, refer to fig. 2 and fig. 3, pile body 1 comprises concrete and steel reinforcement cage 2, steel reinforcement cage 2 includes the main muscle 21 that a plurality of circumference array set up, in this embodiment, main muscle 21 is six, link to each other through stirrup 22 between the adjacent main muscle 21, for the horizontal bearing capacity who improves pile body 1, stirrup 22 is the heliciform setting, can increase stirrup 22's coverage like this, stirrup 22 is better to main muscle 21's fixed effect, the effectual structural strength who improves pile body 1. In this embodiment, the number of the stirrups 22 is two, and the rotation directions of the two stirrups 22 are opposite, so that the coverage area of the stirrups 22 can be further increased, and the bearing capacity of the pile body 1 in the horizontal direction is better.

Refer to fig. 2 and fig. 3, in addition, when the length of pile body 1 is longer, when the transportation, there is pile body 1 self gravity heavier, the atress that is located pile body 1 middle part is the biggest, therefore, the pitch that stirrup 22 is located main muscle 21 middle part is less than its pitch that is located main muscle 21 both ends, it is intensive some with the stirrup 22 setting at main muscle 21 middle part, can effectual improvement 2 middle part of steel reinforcement cage structural strength, and then improve the bending resistance at pile body 1 middle part, improve pile body 1's structural strength, convenient transportation. When the pitch of the stirrup 22 positioned in the middle of the main reinforcement 21 is 1.5 times that of the stirrup 22 positioned at two ends of the main reinforcement 21, the structural strength of the reinforcement cage 2 can be ensured, the waste of the stirrup 22 can be avoided, and the construction cost is saved.

Referring to fig. 4 and 5, in order to conveniently fix the stirrup 22 and the main bar 21, the main bar 21 is externally sleeved with the mounting sleeve 3, the mounting sleeve 3 is a plurality of and is arranged in an array along the length direction of the main bar 21, the surface of the main bar 21 is provided with the transverse groove 4, the transverse groove 4 is perpendicular to the axial direction of the main bar 21, the mounting sleeve 3 is eccentrically provided with a through hole 31 communicated with the transverse groove 4, the size of the through hole 31 is matched with that of the transverse groove 4, and the diameter of the through hole 31 is matched with that of the transverse groove 4. When fixed, after aligning through hole 31 and horizontal groove 4, penetrate steel wire 41 in to through hole 31, outside the both ends of steel wire 41 were located mounting sleeve 3, the middle part of steel wire 41 was located through hole 31 and horizontal groove 4, and after steel wire 41 passed out from mounting sleeve 3, with stirrup 22 ligature on mounting sleeve 3, realize stirrup 22 and mounting sleeve 3 fixed, and then fixed being in the same place stirrup 22 and main muscle 21. During installation, the steel wire 41 can be firstly penetrated into the through hole 31 and the transverse groove 4, the fixing sleeve is positioned on the main reinforcement 21, the fixing position of the stirrup 22 can be determined at the moment, and then the stirrup 22 is directly bound on the fixing sleeve, so that the fixation of the stirrup 22 and the fixing sleeve can be realized.

Referring to fig. 4, in order to adapt to the fixation of stirrups 22 with different pitches, a plurality of transverse grooves 4 are arranged in an array along the length direction of the main rib 21, so that the mounting sleeve 3 can be fixed at any position on the main rib 21, and the adaptability is improved.

Referring to fig. 4 and 5, in order to improve the seismic performance of the pile body 1, a positioning cylinder 5 embedded in concrete is fixed on the main reinforcement 21, the positioning cylinder 5 is arranged along the radial direction of the pile body 1, the opening of the positioning cylinder 5 faces the outside of the pile body 1 and is communicated with the outside, the length of the positioning cylinder 5 is equal to the wall thickness of the pile body 1, two end faces of the positioning cylinder 5 are respectively located on the outer circumferential surface and the inner circumferential surface of the pile body 1, and the positioning cylinder 5 is welded and fixed on the installation cylinder for convenient installation.

Referring to fig. 5 and 6, a positioning pin 51 is arranged in the positioning cylinder 5, the positioning pin 51 is slidably arranged in the positioning cylinder 5 along the length direction of the positioning cylinder 5, a first elastic member for driving the positioning pin 51 to extend out of the positioning cylinder 5 is arranged in the positioning cylinder 5, a fixing member for fixing the positioning pin 51 in the positioning cylinder 5 is further arranged in the positioning cylinder 5, the fixing member fixes the positioning pin 51 in the positioning cylinder 5 before pile driving, so that the outer surface of the pile body 1 is still cylindrical, the resistance of the pile body 1 during pressing down is not increased, after pile driving is completed, the fixing of the fixing member and the positioning cylinder 5 is released, the positioning pin 51 slides outwards under the action of the first elastic member, the positioning pin 51 is driven into the foundation on the periphery of the pile body 1, the contact area between the pile body 1 and the abutment can be increased, meanwhile, the displacement of the pile body 1 in the vertical direction can be limited, and the fixing effect of the pile body 1 and the foundation is effectively improved, the seismic performance of the precast pile is improved.

Referring to fig. 5 and 6, in order to facilitate the driving of the positioning nail 51 into the ground, one end of the positioning nail 51 is provided with a spike 511, the spike 511 is disposed toward the opening of the positioning cylinder 5, the fixing member includes a fixing rod 52 disposed along the length direction of the positioning nail 51, one end of the fixing rod 52 is fixed on the end surface of the positioning nail 51 far away from the spike 511, the other end of the fixing rod extends out of the bottom of the positioning cylinder 5, the extending end of the fixing rod 52 is provided with a wedge 521, after the fixing rod 52 extends out of the positioning cylinder 5, the plane of the wedge 521 can abut against the positioning cylinder 5 under the elastic force of the first elastic member, so as to fix the positioning nail 51 in the positioning cylinder 5, and the bottom of the positioning cylinder 5 is provided with a through hole 55 for. The first elastic element is a first spring 53, one end of the first spring 53 is abutted with the end face of the positioning nail 51, and the other end is abutted with the bottom wall of the positioning cylinder 5.

Referring to fig. 6, in order to make the stress of the positioning nails 51 uniform, two fixing rods 52 are provided, which are parallel to each other and symmetrically arranged about the axis of the positioning nails 51, the wedges 521 on the two fixing rods 52 are symmetrically arranged, the through holes 55 at the bottom of the positioning cylinder 5 can simultaneously allow the two fixing rods 52 to extend out, furthermore, the extending ends of the fixing rods 52 are provided with second springs 54, the second springs 54 are arranged between the two fixing rods 52, the two ends of the second springs 54 are respectively fixed with the corresponding fixing rods 52, the second springs 54 drive the two fixing rods 52 to move away from each other, so that the anti-seismic performance of the fixing member can be effectively improved, and the fixing failure of the positioning nails 51 caused by the sliding of the wedges 521 due to the vibration during pile; in addition, after the fixing rod 52 slides into the sleeve 711, the second spring 54 drives the two fixing rods 52 to move away, the two fixing rods 52 are arranged in a splayed shape, the fixing rod 52 cannot slide out of the through hole 55, and the fixing rod 52 can play a limiting role to prevent the positioning nail 51 from moving back.

Referring to fig. 7, in order to conveniently tension the main bars 21 before casting, end plates 6 fixed to a mold during casting are arranged at two ends of each main bar 21, the end plates 6 are arranged in a circular shape, external threads with opposite turning directions are arranged at two ends of each main bar 21, nuts 7 matched with the external threads at the ends of the main bars 21 are rotatably connected to the two end plates 6, the nuts 7 are arranged in a cylindrical shape, threaded holes matched with the external threads are formed in the nuts 7, outer gear rings 71 are sleeved on the outer peripheral surfaces of the nuts 7, the outer gear rings 71 are connected with the nuts 7 through keys, the outer gear rings 71 and the nuts 7 rotate synchronously, driving gears 62 meshed with the outer gear rings 71 are rotatably arranged at the centers of the end plates 6, when the main bars 21 are required to be tensioned, only the driving gear 62 on one of the end plates 6 needs to be rotated to drive the nuts 7 on the corresponding end, therefore, the two ends of the main ribs 21 can be driven to be away from each other, the tensioning of all the main ribs 21 is realized, the working efficiency is improved, and the equal prestress on each main rib 21 is ensured.

Referring to fig. 7, in order to selectively apply prestress to the main rib 21, the outer gear ring 71 is slidably disposed on the nut 7 along an axial direction of the nut 7, the outer gear ring 71 has a first state engaged with the driving gear 62 and a second state sliding to a position staggered from the driving gear 62, a sleeve 711 is integrally disposed on one end surface of the outer gear ring 71, the sleeve 711 is sleeved outside the nut 7, a screw capable of abutting against an outer peripheral surface of the nut 7 is threadedly connected to the sleeve 711, after the outer gear ring 71 is slidably disposed in place, the screw is tightened, and the driving gear 62 and the nut 7 can be fixed by friction between the screw and an outer wall of the nut 7, so that the driving gear 62 is maintained in the first state or the second state.

Finally, referring to fig. 7, due to the precast piles of different models, the diameters of the pile body 1 are different, the diameters of the circles formed by surrounding the main ribs 21 are also different, in order to adapt to the tightening of the main ribs 21 of different diameters, the nut 7 is arranged on the end plate 6 in a sliding manner along the radial direction of the end plate 6, the outer peripheral surface of the end plate 6 is provided with an open slot 61, the nut 7 is rotatably arranged in the open slot 61, the outer peripheral surface of the nut 7 is provided with a convex ring 72, the inner wall of the open slot 61 is provided with a sliding groove 611 for the convex ring 72 to slide, and the nut 7 can slide and rotate in the open slot. A limiting gear 641 for limiting the outward sliding of the nuts 7 is rotatably arranged between the adjacent nuts 7 on the end plate 6, the thickness of the limiting gear 641 is equal to that of the driving gear 62, a sliding block 64 is slidably arranged on the end plate 6 along the radial direction of the end plate 6, the sliding block 64 is fixed on the end plate 6 through a screw, the rotating shaft of the limiting gear 641 is rotatably arranged on the sliding block 64, and the outer gear ring 71 is fixed at a corresponding position on the end plate 6 under the limiting action of the limiting gear 641 and the driving gear 62. The pile body 1 with different diameters can be poured by replacing the driving gears 62 with different diameters and sliding the limit gear 641. After pouring, the end plates 6 and the nuts 7 are detached from the main ribs 21, so that the end plates 6 and the nuts 7 can be reused, energy is saved, and the novel concrete pouring device is very environment-friendly.

Referring to fig. 7, in order to facilitate installation and fixation of the limit gear 641, a T-shaped groove 63 is provided in the end plate 6 along the radial direction of the end plate 6, and the slider 64 is engaged with the T-shaped groove 63, and the slider 64 can be fixed to the end plate 6 by tightening a screw, thereby fixing the limit gear 641.

The specific implementation process comprises the following steps: before pouring, firstly manufacturing a reinforcement cage 2, fixing an end plate 6 on a mold, fixing a corresponding mounting sleeve 3 on a main reinforcement 21, then mounting nuts 7 at two ends of the main reinforcement 21, placing the nuts 7 in an open slot 61 on the end plate 6, mounting a driving gear 62 and a limiting gear 641, and rotating the driving gear 62 to realize tensioning of the corresponding main reinforcement 21;

then binding the stirrups 22 on the outer surface of the installation cylinder through the steel wires 41 to finish the manufacture of the reinforcement cage 2;

pouring, after the pile body 1 is formed, removing the end plate 6 and the nut 7, and transporting the pile body 1 to a field for installation;

after the pile body 1 is installed, the two fixing rods 52 in the same fixing cylinder are pulled to drive the two fixing rods 52 to approach each other, the fixing rods 52 remove the limitation on the positioning nails 51, the positioning nails 51 extend out of the fixing cylinder under the action of the first springs 53 and are driven into a foundation outside the pile body 1, and the embedding of the precast pile is completed.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The utility model provides a prestressed concrete precast pile, includes pile body (1), pile body (1) comprises concrete and steel reinforcement cage (2), steel reinforcement cage (2) include main muscle (21) that a plurality of circumference arrays set up, and are a plurality of main muscle (21) link to each other its characterized in that through stirrup (22): the pile is characterized in that a positioning cylinder (5) buried in concrete is fixed on the main rib (21), an opening of the positioning cylinder (5) is communicated with the outside of the pile body (1), a positioning nail (51) is arranged in the positioning cylinder (5), the positioning nail (51) is arranged in the positioning cylinder (5) in a sliding manner along the length direction of the positioning cylinder (5), a first elastic piece for driving the positioning nail (51) to extend out of the positioning cylinder (5) is arranged in the positioning cylinder (5), and a fixing piece for fixing the positioning nail (51) in the positioning cylinder (5) is further arranged in the positioning cylinder (5); a spine part (511) is arranged at one end, facing the opening of the positioning cylinder (5), of the positioning nail (51), the fixing part comprises a fixing rod (52) arranged along the length direction of the positioning nail (51), one end of the fixing rod (52) is fixed on the end face, away from the spine part (511), of the positioning nail (51), the other end of the fixing rod extends out of the bottom of the positioning cylinder (5), a wedge block (521) capable of abutting against the positioning cylinder (5) is arranged at the extending end of the fixing rod (52), and a through hole (55) for the fixing rod (52) and the wedge block (521) to extend out is arranged at the bottom of the positioning cylinder (5); the two fixing rods (52) are arranged in parallel, and wedge blocks (521) on the two fixing rods (52) are symmetrically arranged; the utility model discloses a reinforcement installation structure, including main muscle (21), installation cover (3), horizontal groove (4) are equipped with on installation cover (3), main muscle (21) overcoat is equipped with installation cover (3), installation cover (3) are a plurality of and set up along main muscle (21) length direction array, main muscle (21) surface is equipped with horizontal groove (4), install on cover (3) eccentric be equipped with horizontal groove (4) communicating through hole (31), work as horizontal groove (4) communicate with each other with through hole (31) when, wear to be equipped with in through hole (31) and be used for steel wire (41) of stirrup (22) ligature on installation cover (3).

2. The prestressed concrete precast pile according to claim 1, wherein: the transverse grooves (4) are a plurality of and are arranged in an array mode along the length direction of the main ribs (21).

3. A pre-stressed concrete pile according to claim 1 or 2, wherein: main muscle (21) both ends are equipped with when pouring end plate (6) fixed with the mould, main muscle (21) both ends are equipped with and revolve to opposite external screw thread, two rotate on end plate (6) and be connected with main muscle (21) tip external screw thread complex nut (7), the cover is equipped with outer ring gear (71) on nut (7) outer peripheral face, end plate (6) center is rotated and is equipped with driving gear (62) with each outer ring gear (71) meshing.

4. A pre-stressed concrete precast pile according to claim 3, wherein: the outer gear ring (71) is arranged on the nut (7) in a sliding mode along the axial direction of the nut (7), and the outer gear ring (71) has a first state meshed with the driving gear (62) and a second state staggered with the driving gear (62).

5. The prestressed concrete precast pile according to claim 4, wherein: end plate (6) outer peripheral face corresponds with nut (7) and is equipped with open slot (61), nut (7) rotate and set up in open slot (61), it is equipped with limiting gear (641) of the outside roll-off of restriction nut (7) to rotate between two adjacent nuts (7) on end plate (6), limiting gear (641) and outer ring gear (71) meshing on adjacent nut (7).

6. The prestressed concrete precast pile according to claim 1, wherein: the stirrups (22) are spirally arranged, the stirrups (22) are two, and the rotating directions of the stirrups (22) are opposite.

7. A pre-stressed concrete precast pile according to claim 6, wherein the pitch of the stirrup (22) in the middle of the main reinforcement (21) is smaller than the pitch of the stirrup at both ends of the main reinforcement (21).