A pile end post-grouting device for a precast pile bearing stratum abrupt change region

Abstract

The application provides a pile end post-grouting device for a precast pile bearing stratum mutation area, which comprises a pile body, a connecting plate fixedly connected to the lower end of the pile body, a pile wedge fixedly connected to the lower surface of the connecting plate, a plurality of vertical pipes rotatably sleeved in the connecting plate, an inclined pipe fixedly connected to the lower end of each vertical pipe, a slurry outlet opening formed in the surface of the inclined pipe, a plugging mechanism arranged at the end of the inclined pipe away from the vertical pipe, a plurality of conveying mechanisms arranged in the pile body and matched with the vertical pipes, and a feeding mechanism arranged at the upper end of the pile body and used for feeding slurry into the conveying mechanisms; the feeding mechanism feeds the slurry into the conveying mechanisms in a spiral feeding mode, the conveying mechanisms feed the slurry into the vertical pipes in a spiral feeding mode and drive the vertical pipes to rotate, and the plugging mechanism is automatically unplugged under the action of the slurry pressure, and the slurry is injected into the stratum from the slurry outlet opening on the inclined pipe. The application can effectively solve the problem that the slurry in the bearing stratum mutation area preferentially flows to the soft area and the hard area and the grouting in the hard area is insufficient, and significantly improves the uniformity of the pile end enlarged head and the overall bearing capacity.

Description

Technical Field

[0001] This invention relates to the field of precast pile grouting technology, and more specifically, to a post-grouting device for the pile end in the bearing layer abrupt change zone of a precast pile. Background Technology

[0002] In actual construction, many problems often arise with precast piles, such as: the bearing capacity not meeting the design requirements according to the survey data, the designed pile length not being able to be driven to the design elevation, or the pile floating phenomenon caused by excessively fast pile driving speed. These problems are due to both uneven geological conditions and construction technology issues.

[0003] The existing grouting technology involves pre-embedding grouting pipes inside the precast pile body, with the bottom of the pipes extending to near the pile tip. After the pile is driven into place, cement grout is injected into the pile tip using a ground grouting pump. The grout seeps into the cracks in the bearing layer or into the loose soil, and after solidification, it forms an enlarged head or cemented body, thereby significantly improving the pile tip resistance and pile side friction.

[0004] However, existing post-grouting devices for pile ends still have significant technical defects in actual engineering, especially when there are abrupt changes in the bearing stratum (such as alternating soft and hard surfaces, inclined rock surfaces, local lenses, etc.). The problems are particularly prominent in these cases: First, most conventional grouting outlets adopt fixed structures (such as lateral openings or end check valves), and the direction of grout ejection remains unchanged. When there are large differences in the hardness of the stratum at different locations of the pile end, the grout will preferentially flow along the path of least resistance, resulting in excessive grouting in soft areas and insufficient grouting in hard areas, failing to form a uniform enlarged head. Second, existing devices lack active disturbance capabilities. The pile end sediment or loose soil generated during pile driving can easily clog the grouting holes, and the high-pressure grout can only scour local areas, making it difficult to effectively remove the loose layer at all interfaces of the pile end. Third, when the bearing stratum is inclined, the fixed grouting head cannot sense the dip angle of the stratum, and the grout often concentrates on the lower side, causing the pile end on the higher side to be suspended or have low bearing capacity, ultimately leading to uneven settlement of the pile foundation, and even causing cracking or tilting of the superstructure.

[0005] Therefore, it is necessary to propose a post-grouting device for the pile tip in the abrupt change zone of the bearing stratum of precast piles to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of inconvenient use of post-grouting devices at the pile end in areas of abrupt change in the bearing stratum of some precast piles.

[0007] To achieve the above-mentioned objectives and improve the above-mentioned problems, the present invention adopts the following technical solution:

[0008] This invention provides a post-grouting device for the pile end in a precast pile bearing stratum abrupt change zone, comprising a pile body, a connecting plate fixedly connected to the lower end of the pile body, a pile wedge fixedly connected to the lower surface of the connecting plate, a plurality of vertical tubes rotatably sleeved inside the connecting plate, an inclined tube inclined away from the vertical axis of the pile body fixedly connected to the lower end of the vertical tube, a grout outlet opening on the surface of the inclined tube, a sealing mechanism provided at the end of the inclined tube away from the vertical tube, a plurality of conveying mechanisms matching the vertical tubes provided inside the pile body, a feeding mechanism provided at the upper end of the pile body to feed grout into the conveying mechanism; the feeding mechanism feeds grout into the conveying mechanism by spiral feeding, the conveying mechanism conveys grout into the vertical tubes by spiral feeding and drives the vertical tubes to rotate, and at the same time the sealing mechanism automatically releases the seal under the action of grout pressure, and the grout is injected into the stratum from the grout outlet on the inclined tube.

[0009] As a preferred technical solution of this application, the sealing mechanism includes a fixed block, which is tubular, closed at one end and open at the other. The open end of the fixed block is fixedly connected to the end of the inclined tube away from the vertical tube. A movable chamber is formed inside the fixed block and is connected to the inside of the inclined tube. The movable chamber is irregularly shaped, with its diameter near the open end matching that of the inclined tube and its diameter near the closed end being larger than that of the inclined tube. A sliding plate is slidably connected inside the movable chamber near the closed end, and a sealing column is fixedly connected to the surface of the sliding plate. The sealing column can slidably pass through the open end of the movable chamber and extend into the inside of the inclined tube. A return spring is fixedly connected between the sliding plate and the closed end of the movable chamber.

[0010] As a preferred technical solution of this application, the pile body has multiple rotating grooves opened along its length, and the opening position of the rotating grooves corresponds to the position of the vertical pipe.

[0011] As a preferred technical solution of this application, the conveying mechanism includes a rotating tube, which is located inside the pile body and rotatably sleeved inside the rotating groove. A transition tube is fixedly connected to the lower end of the rotating tube, and a fixed tube is fixedly connected to the lower end of the transition tube. The fixed tube and the transition tube are also rotatably sleeved inside the rotating groove. The lower end of the fixed tube is fixedly connected to the vertical pipe. The diameter of the rotating tube is larger than the diameter of the fixed tube. Several first spiral blades are fixedly installed inside the rotating tube.

[0012] As a preferred technical solution of this application, the feeding mechanism includes a fixed plate, which is fixedly connected to the upper surface of the pile body. A liquid storage chamber is opened inside the fixed plate, and a guide cone is fixedly connected to the bottom wall of the fixed plate. Multiple rotating tubes rotate through the liquid storage chamber and communicate with it. The upper end face of the rotating tube is flush with the bottom wall of the fixed plate.

[0013] As a preferred technical solution of this application, a rotating component is rotatably sleeved on the upper end face of the fixed disk, and an installation tube is fixedly sleeved inside the rotating component. The lower end of the installation tube extends into the interior of the fixed disk, and an agitation mechanism is provided on the surface of the installation tube. When the slurry enters the storage chamber, the slurry is sent into the rotating tube by the agitation mechanism.

[0014] As a preferred technical solution of this application, the stirring mechanism includes a plurality of connecting rods, all of which are fixedly connected to the outer wall of the lower end of the mounting tube and are evenly arranged in a circumferential direction. Scrapers are fixedly connected to the lower sides of both ends of the connecting rods, and a plurality of stirring rods are fixedly connected to the lower side of the middle part of the connecting rods.

[0015] As a preferred technical solution of this application, the upper end of the installation pipe is provided with a liquid inlet pipe, a rotating flange is provided between the liquid inlet pipe and the installation pipe, and a number of second spiral blades are fixedly connected inside the installation pipe.

[0016] As a preferred technical solution of this application, a plurality of the first spiral blades are arranged in a circumferential array.

[0017] As a preferred technical solution in this application, there are two to six vertical pipes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) By coordinating the structure of the inlet pipe, the second spiral blade, the installation pipe, the rotating pipe, the first spiral blade, the vertical pipe, and the inclined pipe, the function of automatically driving the grouting pipe to rotate during the grout transportation process is realized. When the grout flows, it impacts the spiral blade, causing the inclined pipe to rotate continuously at the pile end, and the grout is evenly sprayed into the strata in different directions. This effectively solves the problem that the grout in the bearing layer change area preferentially flows to the soft area and the grouting in the hard area is insufficient, and significantly improves the uniformity and overall bearing capacity of the pile end enlarged head.

[0020] (2) By coordinating the structures such as vertical pipe, inclined pipe, grout outlet, fixed block, movable chamber, sliding plate, sealing column, and reset spring, the unidirectional conduction and automatic reset sealing function of the grout outlet are realized. During grouting, the grout pressure automatically pushes open the sealing column. After grouting stops, the reset spring pushes the sealing column to close the outlet, preventing grout backflow and external soil backflow. This avoids the grouting hole being blocked by sediment or loose soil, ensuring the smooth progress of subsequent grouting operations and improving the reliability of the device under complex geological conditions.

[0021] (3) Through the cooperation between the installation pipe, connecting rod, scraper, stirring rod, fixed plate, storage chamber, and guide cone, the active stirring and uniform distribution of grout before entering each grouting branch is realized. The rotation of the installation pipe drives the scraper and stirring rod to continuously stir the grout in the storage chamber to prevent cement grout from settling and segregating. At the same time, the guide cone distributes the grout evenly to the surrounding area to ensure that the grout composition and pressure obtained by the four rotating pipes are consistent, thereby avoiding local grouting quality differences caused by uneven grout. Attached Figure Description

[0022] Figure 1 A schematic diagram of the post-grouting device at the pile tip in the abrupt change zone of the bearing stratum of the precast pile provided in this application;

[0023] Figure 2 A schematic diagram of the pile body in the post-grouting device at the pile tip of the precast pile bearing stratum abrupt change zone provided in this application;

[0024] Figure 3 A cross-sectional structural schematic diagram of the pile body in the post-grouting device at the pile tip of the precast pile bearing stratum abrupt change zone provided in this application;

[0025] Figure 4 A schematic diagram of the connecting plate in the post-grouting device at the pile end of the precast pile bearing stratum abruptly changed region provided in this application;

[0026] Figure 5 A first schematic cross-sectional view of the inclined pipe in the post-grouting device at the pile end in the abrupt change zone of the bearing stratum of the precast pile provided in this application;

[0027] Figure 6 A second schematic cross-sectional view of the inclined pipe in the post-grouting device at the pile tip in the abrupt change zone of the bearing stratum of the precast pile provided in this application;

[0028] Figure 7 A partial cross-sectional view of the rotating pipe in the post-grouting device at the pile tip in the abrupt change zone of the bearing stratum of the precast pile provided in this application;

[0029] Figure 8 A cross-sectional structural diagram of the fixing plate in the post-grouting device at the pile end for the abrupt change zone of the bearing stratum of the precast pile provided in this application.

[0030] The image shows:

[0031] 1. Pile body; 2. Pile wedge; 3. Vertical pipe; 4. Grout outlet; 5. Fixing block; 6. Movable chamber; 7. Sliding plate; 8. Sealing column; 9. Return spring; 10. Rotating groove; 11. Rotating pipe; 12. Transition pipe; 13. Fixing pipe; 14. First helical blade; 15. Fixing disc; 16. Liquid storage chamber; 17. Guide cone; 18. Rotating component; 19. Installation pipe; 20. Second helical blade; 21. Connecting rod; 22. Scraper; 23. Stirring rod; 24. Connecting plate; 25. Inclined pipe; 26. Rotating flange; 27. Liquid inlet pipe. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0034] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] Please refer to Figures 1-8 A post-grouting device for the bearing stratum of a precast pile in a region of abrupt change includes a pile body 1. A connecting plate 24 is fixedly connected to the lower end of the pile body 1. A pile wedge 2 is fixedly connected to the lower surface of the connecting plate 24. Four vertical pipes 3 arranged in a circular array are rotatably fitted inside the connecting plate 24. Since the four vertical pipes 3 have the same structure, the following description focuses on one vertical pipe 3. An inclined pipe 25, which slopes downwards away from the vertical axis of the pile body 1, is fixedly connected to the lower end of the vertical pipe 3. The inclined pipe 25 is used to... To facilitate grout flow, a grout outlet 4 is provided on the surface of the inclined tube 25. A sealing mechanism is provided at the end of the inclined tube 25 away from the vertical tube 3. Four conveying mechanisms are provided inside the pile body 1, and a feeding mechanism is provided at the upper end of the pile body 1. The feeding mechanism feeds grout into the conveying mechanism by means of a screw feeder. The conveying mechanism also feeds grout into the vertical tube 3 by means of a screw feeder and drives the vertical tube 3 to rotate. At the same time, the sealing mechanism automatically releases the seal under the pressure of the grout, and the grout is injected into the formation from the grout outlet 4 on the inclined tube 25.

[0037] Furthermore, since the inclined tube 25 is exposed below the connecting plate, in order to prevent the sediment or hard soil clods from directly squeezing the inclined tube 25 during the pile driving process, causing deformation or damage, annular reinforcing ribs or wear-resistant sleeves can be added to the outer surface of the inclined tube 25. At the same time, the material of the inclined tube 25 is made of high-strength steel pipe (such as No. 45 steel or seamless steel pipe).

[0038] Furthermore, the pile wedge 2 is cone-shaped and is welded from four triangular steel plates. A grout channel is formed between the steel plates at the bottom of the pile body 1. The grout channel is separated from the soil by the steel plates. The grout entering the grout channel from the grout outlet 4 will preferentially flow into the soil of the corresponding area.

[0039] Furthermore, such as Figures 1-8 As shown, the sealing mechanism includes a fixed block 5, which is tubular with one end closed and the other end open. The open end of the fixed block 5 is fixedly connected to the end of the inclined tube 25 away from the vertical tube 3. The fixed block 5 has a movable chamber 6 inside, which is connected to the inside of the inclined tube 25. The movable chamber 6 is irregularly shaped, with its diameter near the open end matching that of the inclined tube 25 and its diameter near the closed end being larger than that of the inclined tube 25. A sliding plate 7 is slidably connected inside the movable chamber 6 near the closed end (to prevent the sliding plate 7 from sliding out of the movable chamber 6). A sealing column 8 is fixedly connected to the surface of the sliding plate 7. The sealing column 8 can slide through the open end of the movable chamber 6 and extend into the inside of the inclined tube 25. A return spring 9 is fixedly connected between the sliding plate 7 and the closed end of the movable chamber 6.

[0040] The fixed block 5 is connected to the end of the inclined tube 25 by welding or integral molding, and the internal movable chamber 6 is connected to the inside of the inclined tube 25.

[0041] Thus, by using the reset spring 9, when there is no grout in the inclined tube 25, the reset spring 9 can keep the blocking column 8 blocking the grout outlet 4. When the inclined tube 25 is filled with grout, the grout will push the blocking column 8 to slide. At this time, the sliding plate 7 will also slide, thereby forcing the reset spring 9 to deform. After the grout is stopped, the elastic potential energy stored in the reset spring 9 will cause the blocking column 8 to block the grout outlet 4 again, so that the grout outlet 4 can only discharge grout, and the grout cannot flow back into the grouting channel, thereby solving the problem of grout return.

[0042] In addition, the inclined tube 25 can push the surrounding loose sediment to the side during rotation, reducing rotational resistance. At the same time, the rotation is started with a lower pressure in the initial stage of grouting. After the inclined tube 25 loosens the surrounding soil, the grouting pressure is increased to ensure that the inclined tube 25 can rotate normally. If the stratum hardness is high, pulse pressure can be applied in advance by the grouting pump to make the inclined tube 25 produce a small amplitude reciprocating rotation, loosen the surrounding soil, and then enter the continuous rotation grouting mode.

[0043] Furthermore, such as Figures 1-8 As shown, four rotating grooves 10 arranged in a circular array are provided inside the pile body 1. The rotating grooves 10 are opened along the length direction of the pile body 1, and their axes are parallel to the axis of the precast pile. The rotating grooves 10 are distributed in a circular array on the cross-section of the precast pile, with a total of four, corresponding one-to-one with the positions of the four vertical pipes 3.

[0044] Furthermore, such as Figures 1-8 As shown, the conveying mechanism includes a rotating pipe 11, which is located inside the pile body 1 and rotatably sleeved inside the rotating groove 10. The lower end of the rotating pipe 11 is fixedly connected to a transition pipe 12, and the lower end of the transition pipe 12 is fixedly connected to a fixed pipe 13. The fixed pipe 13 and the transition pipe 12 are also rotatably sleeved inside the rotating groove 10. The lower end of the fixed pipe 13 is fixedly connected to the vertical pipe 3. The diameter of the rotating pipe 11 is larger than the diameter of the fixed pipe 13. Several first spiral blades 14 are fixedly installed inside the rotating pipe 11.

[0045] In the above embodiment, the cross-section of the transition pipe 12 is tapered, which allows the fluid to accelerate smoothly and avoids energy loss and flow disruption.

[0046] A double sealing structure can be set between the rotating mating surfaces of the connecting plate 24 and the vertical pipe 3: the first layer is a wear-resistant elastic sealing ring to prevent external mud and fine sediment from entering; the second layer is a labyrinth sealing ring to further block coarse loose soil. In addition, grease can be pre-filled inside the rotating groove 10, and a grease injection hole communicating with it can be set at the top of the pile body 1, so that grease can be replenished regularly before grouting to ensure smooth rotation of the rotating pipe system.

[0047] Furthermore, such as Figures 1-8 As shown, several first helical blades 14 are arranged in a circular array.

[0048] Thus, when the slurry enters the rotating tube 11, it comes into contact with the first spiral blade 14, which forces the rotating tube 11 to rotate under the action of the first spiral blade 14. The rotation of the rotating tube 11 then drives the transition tube 12 and the fixed tube 13 to rotate. Subsequently, the rotation of the fixed tube 13 drives the rotation of the vertical tube 3 and the inclined tube 25, ultimately distributing the slurry in various locations and avoiding local accumulation.

[0049] Furthermore, such as Figures 1-8As shown, the feeding mechanism includes a fixed plate 15, which is fixedly connected to the upper surface of the pile body 1. A liquid storage chamber 16 is opened inside the fixed plate 15. A guide cone 17 is fixedly connected to the bottom wall of the fixed plate 15. Four rotating tubes 11 are rotatably inserted to communicate with the liquid storage chamber 16, and the upper end face of the rotating tube 11 is flush with the bottom wall of the fixed plate 15. A rotating component 18 is rotatably sleeved on the upper end face of the fixed plate 15. An installation tube 19 is fixedly sleeved inside the rotating component 18. The lower end of the installation tube 19 extends into the interior of the fixed plate 15. An agitation mechanism is provided on the surface of the installation tube 19. When the slurry enters the liquid storage chamber 16, the slurry is sent into the rotating tube 11 by the agitation mechanism.

[0050] In the above embodiment, the fixing plate 15 is fixedly connected to the pile body 1 by pre-embedded bolts or welding. This connection is completed during the production stage of the precast pile 1: before concrete pouring, the positioning mold of the fixing plate 15 is fixed to the end of the pile mold. After the pile body has cured to the design strength, the fixing plate 15 is fastened to the upper surface of the precast pile 1 with high-strength bolts, or continuously welded along the joint. The fixing plate 15 is sunk into the stratum along with the precast pile. After the pile is driven into place, grouting is carried out directly without the need for disassembly or secondary installation. The fixing plate 15 is made of the same material as the inclined tube 25.

[0051] Furthermore, such as Figures 1-8 As shown, an inlet pipe 27 is provided at the upper end of the mounting pipe 19, a rotating flange 26 is provided between the inlet pipe 27 and the mounting pipe 19, and several second spiral blades 20 are fixedly connected inside the mounting pipe 19.

[0052] In the above embodiment, the assembly method of the second helical blade 20 is the same as that of the first helical blade 14, so that when the slurry flows from the inside of the mounting pipe 19, the mounting pipe 19 can be forced to rotate.

[0053] Thus, the slurry is delivered to the interior of the mounting pipe 19 through the inlet pipe 27 and the rotating flange 26. Under the action of the second spiral blade 20, the mounting pipe 19 will rotate. Subsequently, the slurry will flow to the surroundings under the action of the guide cone 17, and finally the slurry will enter the interior of the rotating pipe 11.

[0054] Furthermore, such as Figures 1-8 As shown, the stirring mechanism includes several connecting rods 21, all of which are fixedly connected to the outside of the mounting tube 19. A scraper 22 is fixedly connected to the lower end of the connecting rod 21, and an stirring rod 23 is fixedly connected to the crossbar surface of the connecting rod 21.

[0055] Thus, when the installation pipe 19 rotates, it can drive the scraper 22 and the stirring rod 23 to perform circular motion, thereby further ensuring the fluidity of the internal slurry.

[0056] It should be noted that this scheme is particularly suitable for precast concrete pipe piles or square piles with a diameter of 600mm and above. Under complex geological conditions such as interlayered soft and hard layers, inclined bedrock surfaces, local hard interlayers or lenses in the bearing layer, it can significantly improve the uniformity of grouting. For small-diameter precast piles (such as those with a diameter of less than 400mm), the arrangement can be simplified to two grouting channels, and the number of rotating slots 10 can be adjusted accordingly.

[0057] The process of using the post-grouting device at the pile tip in the abrupt change zone of the bearing stratum of the precast pile provided by this invention is as follows:

[0058] First, connect the external grouting pump pipeline to the rotating flange 26 at the upper end of the inlet pipe 27, start the grouting pump, and the cement grout enters the installation pipe 19 through the inlet pipe 27. Multiple second spiral blades 20 are fixed circumferentially inside the installation pipe 19. The high-speed flowing grout impacts the second spiral blades 20, forcing the installation pipe 19 to start rotating inside the rotating part 18. When the installation pipe 19 rotates, it drives the agitation mechanism composed of the connecting rod 21, scraper 22 and agitator 23 to rotate synchronously, continuously agitating the grout in the storage chamber 16 of the fixed plate 15 to prevent cement grout from settling and segregating, and to ensure that the grout is uniform.

[0059] After the grout flows out from the lower end of the installation pipe 19, it falls onto the guide cone 17. The conical surface of the guide cone 17 evenly distributes the grout to the surrounding area, allowing the grout to enter the upper ports of the four rotating pipes 11. The rotating pipes 11 are rotatably fitted into the rotating grooves 10 inside the pile body 1. Several first spiral blades 14 are also circumferentially fixed on their inner walls. After the grout enters the rotating pipes 11, it flows downward and impacts the first spiral blades 14, thereby driving the rotating pipes 11 to rotate within the rotating grooves 10. The lower end of the rotating pipes 11 is fixedly connected to the transition pipe 12, the lower end of the transition pipe 12 is fixedly connected to the fixed pipe 13, and the lower end of the fixed pipe 13 is fixedly connected to the vertical pipe 3. Therefore, the rotation of the rotating pipes 11 will sequentially drive the transition pipe 12, the fixed pipe 13, the vertical pipe 3, and the inclined pipe 25 to rotate together.

[0060] The grout flows into the inclined pipe 25 through the vertical pipe 3. The inclined pipe 25 has a grout outlet 4 on its surface. In the initial state, the return spring 9 pushes the sliding plate 7 to block the grout outlet 4 with the sealing column 8. As the grout pressure gradually increases and overcomes the elastic force of the return spring 9, the grout pushes the sealing column 8 to slide outward. The sliding plate 7 moves in the movable chamber 6, and the sealing column 8 leaves the grout outlet 4. The grout outlet 4 opens, and the grout can be sprayed out from the side of the rotating inclined pipe 25. Because the inclined pipe 25 continues to rotate, the grout can be sprayed at multiple angles and in all directions to the strata in different directions around the pile end, avoiding the grout from flowing in only one direction.

[0061] When the grouting pump stops working, the internal pressure of the inclined pipe 25 drops, and the elastic force of the reset spring 9 pushes the sliding plate 7 and the sealing column 8 to reset. The sealing column 8 re-closes the grout outlet 4 to prevent water or mud in the external soil from flowing back into the grouting pipeline, and also to prevent the injected grout from flowing back, thus ensuring the grouting effect. The connecting plate 24 and the pile wedge 2 at the lower end of the pile body 1 help the pile body 1 sink into the bearing layer and stabilize the position of the pile end.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] Obviously, the embodiments described above are merely some embodiments of the present invention, not all embodiments. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A post-grouting device for the pile tip in a region of abrupt change in the bearing stratum of a precast pile, characterized in that, The system includes a pile body (1), a connecting plate (24) is fixedly connected to the lower end of the pile body (1), a pile wedge (2) is fixedly connected to the lower surface of the connecting plate (24), a plurality of vertical pipes (3) are rotatably sleeved inside the connecting plate (24), an inclined pipe (25) is fixedly connected to the lower end of the vertical pipe (3) and inclined pipe (25) is inclined away from the vertical axis of the pile body (1), a grout outlet (4) is opened on the surface of the inclined pipe (25), a sealing mechanism is provided at the end of the inclined pipe (25) away from the vertical pipe (3), a plurality of conveying mechanisms matching the vertical pipe (3) are provided inside the pile body (1), and a feeding mechanism is provided at the upper end of the pile body (1); the feeding mechanism feeds grout into the conveying mechanism by spiral feeding, the conveying mechanism feeds grout into the vertical pipe (3) by spiral feeding and drives the vertical pipe (3) to rotate, and at the same time the sealing mechanism automatically releases the seal under the action of grout pressure, and the grout is injected into the formation from the grout outlet (4) on the inclined pipe (25).

2. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 1, characterized in that, The sealing mechanism includes a fixed block (5), which is tubular with one end closed and the other end open. The open end of the fixed block (5) is fixedly connected to the end of the inclined tube (25) away from the vertical tube (3). The fixed block (5) has a movable chamber (6) inside, which is connected to the inside of the inclined tube (25). The movable chamber (6) is irregularly shaped, with its diameter near the open end matching that of the inclined tube (25) and its diameter near the closed end being larger than that of the inclined tube (25). A sliding plate (7) is slidably connected inside the movable chamber (6) near the closed end. A sealing column (8) is fixedly connected to the surface of the sliding plate (7). The sealing column (8) can slide through the open end of the movable chamber (6) and extend into the inside of the inclined tube (25). A return spring (9) is fixedly connected between the sliding plate (7) and the closed end of the movable chamber (6).

3. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 2, characterized in that, The pile body (1) has multiple rotating grooves (10) along its length inside, and the opening position of the rotating grooves (10) corresponds to the position of the vertical pipe (3).

4. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 3, characterized in that, The conveying mechanism includes a rotating pipe (11), which is located inside the pile body (1) and rotatably sleeved inside the rotating groove (10). The lower end of the rotating pipe (11) is fixedly connected to a transition pipe (12), and the lower end of the transition pipe (12) is fixedly connected to a fixed pipe (13). The fixed pipe (13) and the transition pipe (12) are also rotatably sleeved inside the rotating groove (10). The lower end of the fixed pipe (13) is fixedly connected to the vertical pipe (3). The diameter of the rotating pipe (11) is larger than the diameter of the fixed pipe (13). Several first spiral blades (14) are fixedly installed inside the rotating pipe (11).

5. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 4, characterized in that, The feeding mechanism includes a fixed plate (15), which is fixedly connected to the upper surface of the pile body (1). The fixed plate (15) has a liquid storage chamber (16) inside. The bottom wall of the fixed plate (15) is fixedly connected to a guide cone (17). Multiple rotating tubes (11) rotate through to communicate with the liquid storage chamber (16), and the upper end face of the rotating tube (11) is flush with the bottom wall of the fixed plate (15).

6. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 5, characterized in that, The upper end face of the fixed disk (15) is rotatably fitted with a rotating component (18), and the inside of the rotating component (18) is fixedly fitted with an installation tube (19). The lower end of the installation tube (19) extends into the interior of the fixed disk (15). The surface of the installation tube (19) is provided with a stirring mechanism. When the slurry enters the storage chamber (16), the slurry is sent into the rotating tube (11) by the stirring mechanism.

7. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 6, characterized in that, The stirring mechanism includes several connecting rods (21), which are fixedly connected to the outer wall of the lower end of the mounting tube (19) and are evenly arranged in a circumferential direction. Scrapers (22) are fixedly connected to the lower sides of both ends of the connecting rods (21), and several stirring rods (23) are fixedly connected to the lower side of the middle part of the connecting rods (21).

8. The post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 7, characterized in that, The upper end of the mounting pipe (19) is provided with an inlet pipe (27), and a rotating flange (26) is provided between the inlet pipe (27) and the mounting pipe (19). Several second spiral blades (20) are fixedly connected inside the mounting pipe (19).

9. A post-grouting device for the bearing stratum abrupt change zone of a precast pile according to claim 8, characterized in that, Several of the first spiral blades (14) are arranged in a circular array.

10. A post-grouting device for the bearing stratum abrupt change zone of a precast pile according to any one of claims 1-9, characterized in that, The vertical tubes (3) are two to six.

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